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\n  \n Animal Interactions\n \n \n (112)\n \n \n
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\n \n\n \n \n \n \n \n Submersed aquatic vegetation in chesapeake bay: Sentinel species in a changing world.\n \n \n \n\n\n \n Orth, R. J.; Dennison, W. C.; Lefcheck, J. S.; Gurbisz, C.; Hannam, M.; Keisman, J.; Landry, J. B.; Moore, K. A.; Murphy, R. R.; Patrick, C. J.; Testa, J.; Weller, D. E.; and Wilcox, D. J.\n\n\n \n\n\n\n 2017.\n Publication Title: BioScience\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 2 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@book{orth_submersed_2017-2,\n\ttitle = {Submersed aquatic vegetation in chesapeake bay: {Sentinel} species in a changing world},\n\tabstract = {Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.},\n\tauthor = {Orth, Robert J. and Dennison, William C. and Lefcheck, Jonathan S. and Gurbisz, Cassie and Hannam, Michael and Keisman, Jennifer and Landry, J. Brooke and Moore, Kenneth A. and Murphy, Rebecca R. and Patrick, Christopher J. and Testa, Jeremy and Weller, Donald E. and Wilcox, David J.},\n\tyear = {2017},\n\tdoi = {10.1093/biosci/bix058},\n\tnote = {Publication Title: BioScience},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.\n
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\n \n\n \n \n \n \n \n Faunal communities are invariant to fragmentation in experimental seagrass landscapes.\n \n \n \n\n\n \n Lefcheck, J. S.; Marion, S. R.; Lombana, A. V.; and Orth, R. J.\n\n\n \n\n\n\n PLoS ONE. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{lefcheck_faunal_2016,\n\ttitle = {Faunal communities are invariant to fragmentation in experimental seagrass landscapes},\n\tdoi = {10.1371/journal.pone.0156550},\n\tabstract = {Human-driven habitat fragmentation is cited as one of the most pressing threats facing many coastal ecosystems today. Many experiments have explored the consequences of fragmentation on fauna in one foundational habitat, seagrass beds, but have either surveyed along a gradient of existing patchiness, used artificial materials to mimic a natural bed, or sampled over short timescales. Here, we describe faunal responses to constructed fragmented landscapes varying from 4-400 m2 in two transplant garden experiments incorporating live eelgrass (Zostera marina L.). In experiments replicated within two subestuaries of the Chesapeake Bay, USA across multiple seasons and non-consecutive years, we comprehensively censused mesopredators and epifaunal communities using complementary quantitative methods. We found that community properties, including abundance, species richness, Simpson and functional diversity, and composition were generally unaffected by the number of patches and the size of the landscape, or the intensity of sampling. Additionally, an index of competition based on species co-occurrences revealed no trends with increasing patch size, contrary to theoretical predictions. We extend conclusions concerning the invariance of animal communities to habitat fragmentation from small-scale observational surveys and artificial experiments to experiments conducted with actual living plants and at more realistic scales. Our findings are likely a consequence of the rapid life histories and high mobility of the organisms common to eelgrass beds, and have implications for both conservation and restoration, suggesting that even small patches can rapidly promote abundant and diverse faunal communities.},\n\tjournal = {PLoS ONE},\n\tauthor = {Lefcheck, Jonathan S. and Marion, Scott R. and Lombana, Alfonso V. and Orth, Robert J.},\n\tyear = {2016},\n\tpmid = {27244652},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Human-driven habitat fragmentation is cited as one of the most pressing threats facing many coastal ecosystems today. Many experiments have explored the consequences of fragmentation on fauna in one foundational habitat, seagrass beds, but have either surveyed along a gradient of existing patchiness, used artificial materials to mimic a natural bed, or sampled over short timescales. Here, we describe faunal responses to constructed fragmented landscapes varying from 4-400 m2 in two transplant garden experiments incorporating live eelgrass (Zostera marina L.). In experiments replicated within two subestuaries of the Chesapeake Bay, USA across multiple seasons and non-consecutive years, we comprehensively censused mesopredators and epifaunal communities using complementary quantitative methods. We found that community properties, including abundance, species richness, Simpson and functional diversity, and composition were generally unaffected by the number of patches and the size of the landscape, or the intensity of sampling. Additionally, an index of competition based on species co-occurrences revealed no trends with increasing patch size, contrary to theoretical predictions. We extend conclusions concerning the invariance of animal communities to habitat fragmentation from small-scale observational surveys and artificial experiments to experiments conducted with actual living plants and at more realistic scales. Our findings are likely a consequence of the rapid life histories and high mobility of the organisms common to eelgrass beds, and have implications for both conservation and restoration, suggesting that even small patches can rapidly promote abundant and diverse faunal communities.\n
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\n \n\n \n \n \n \n \n Predator–prey interactions in a restored eelgrass ecosystem: strategies for maximizing success of reintroduced bay scallops (Argopecten irradians).\n \n \n \n\n\n \n Schmitt, E. L.; Luckenbach, M. W.; Lefcheck, J. S.; and Orth, R. J.\n\n\n \n\n\n\n Restoration Ecology. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{schmitt_predatorprey_2016,\n\ttitle = {Predator–prey interactions in a restored eelgrass ecosystem: strategies for maximizing success of reintroduced bay scallops ({Argopecten} irradians)},\n\tdoi = {10.1111/rec.12353},\n\tabstract = {Predation is a key determinant of community structure and function, and thus should play a central role in successful ecological restoration strategies. The bay scallop, Argopecten irradians, was once abundant in the coastal bays of Virginia, U.S.A., until the complete loss of their eelgrass habitat, Zostera marina, in the 1930s. With the successful restoration of Z. marina in these coastal bays, attention has turned to reintroducing A. irradians with the intent of producing a self-sustaining population. The success of this effort requires an understanding of the sources and degree of natural mortality that A. irradians experiences throughout their ontogeny. The objectives of this study were to: (1) quantify predatory mortality during two successive life history stages of A. irradians, in both spring and fall spawns and (2) identify possible predators of A. irradians in the Virginia coastal bays. We conducted tethering experiments to quantify the proportional losses due to predation, and used otter trawls and suction samples to characterize the predator community over two consecutive years. Losses due to predation ranged from 4 to 80\\% per day, with smaller juveniles ({\\textbackslash}textless15 mm shell height) experiencing greater mortality in 2013, and larger juveniles ({\\textbackslash}textgreater20 mm shell height) in 2014, which we infer is driven by the absence and presence of adult blue crabs in 2013 and 2014, respectively. We propose that managers should look toward relatively inexpensive predator surveys to best judge both when and at what size restored species should be introduced into the wild.},\n\tjournal = {Restoration Ecology},\n\tauthor = {Schmitt, Erika L. and Luckenbach, Mark W. and Lefcheck, Jonathan S. and Orth, Robert J.},\n\tyear = {2016},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Predation is a key determinant of community structure and function, and thus should play a central role in successful ecological restoration strategies. The bay scallop, Argopecten irradians, was once abundant in the coastal bays of Virginia, U.S.A., until the complete loss of their eelgrass habitat, Zostera marina, in the 1930s. With the successful restoration of Z. marina in these coastal bays, attention has turned to reintroducing A. irradians with the intent of producing a self-sustaining population. The success of this effort requires an understanding of the sources and degree of natural mortality that A. irradians experiences throughout their ontogeny. The objectives of this study were to: (1) quantify predatory mortality during two successive life history stages of A. irradians, in both spring and fall spawns and (2) identify possible predators of A. irradians in the Virginia coastal bays. We conducted tethering experiments to quantify the proportional losses due to predation, and used otter trawls and suction samples to characterize the predator community over two consecutive years. Losses due to predation ranged from 4 to 80% per day, with smaller juveniles (\\textless15 mm shell height) experiencing greater mortality in 2013, and larger juveniles (\\textgreater20 mm shell height) in 2014, which we infer is driven by the absence and presence of adult blue crabs in 2013 and 2014, respectively. We propose that managers should look toward relatively inexpensive predator surveys to best judge both when and at what size restored species should be introduced into the wild.\n
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\n \n\n \n \n \n \n \n Trophic transfer in seagrass systems: Estimating seasonal production of an abundant seagrass fish, Bairdiella chrysoura, in lower Chesapeake Bay.\n \n \n \n\n\n \n Sobocinski, K. L.; and Latour, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{sobocinski_trophic_2015,\n\ttitle = {Trophic transfer in seagrass systems: {Estimating} seasonal production of an abundant seagrass fish, {Bairdiella} chrysoura, in lower {Chesapeake} {Bay}},\n\tdoi = {10.3354/meps11163},\n\tabstract = {Silver perch Bairdiella chrysoura is a seasonally abundant fish in lower Chesapeake Bay seagrass habitats. Young-of-the-year fish recruit to these habitats in June and rear for the remainder of the summer before migrating to deeper habitats in the Bay and offshore as seawater cools in the fall. This species has been shown to be abundant in seagrass habitats, yet like many fishes in these habitats, little is known about its growth and production, and thus the contribution of this habitat type to overall production. We developed a bioenergetics model to estimate individual silver perch growth and calibrated this model using field-collected size data. Abundance data were used to develop a generalized additive model for predicting abundance over the simulation period (15 June to 15 October). We used the individual-based model output and estimated abundances to calculate total production. The calibrated bioenergetics model showed silver perch growth of approximately 0.19 g d-1 for total growth of 23.2 g over the simulation period. Peak abundance occurred in July with estimated values of 0.2 ind. m-2. The highest biomass was observed shortly after peak abundance. Total production for silver perch was estimated to be 22.9 g m-2 in the seagrass habitats measured. With an estimated 8100 ha of seagrass habitat in the lower Chesapeake Bay in 2010, silver perch contribute a considerable amount of biomass production. As an annually migrating species, silver perch export in excess of 7400 t of biomass to the near-coastal ecosystem, providing a trophic subsidy from seagrass habitats via trophic transfer.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Sobocinski, Kathryn L. and Latour, Robert J.},\n\tyear = {2015},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Silver perch Bairdiella chrysoura is a seasonally abundant fish in lower Chesapeake Bay seagrass habitats. Young-of-the-year fish recruit to these habitats in June and rear for the remainder of the summer before migrating to deeper habitats in the Bay and offshore as seawater cools in the fall. This species has been shown to be abundant in seagrass habitats, yet like many fishes in these habitats, little is known about its growth and production, and thus the contribution of this habitat type to overall production. We developed a bioenergetics model to estimate individual silver perch growth and calibrated this model using field-collected size data. Abundance data were used to develop a generalized additive model for predicting abundance over the simulation period (15 June to 15 October). We used the individual-based model output and estimated abundances to calculate total production. The calibrated bioenergetics model showed silver perch growth of approximately 0.19 g d-1 for total growth of 23.2 g over the simulation period. Peak abundance occurred in July with estimated values of 0.2 ind. m-2. The highest biomass was observed shortly after peak abundance. Total production for silver perch was estimated to be 22.9 g m-2 in the seagrass habitats measured. With an estimated 8100 ha of seagrass habitat in the lower Chesapeake Bay in 2010, silver perch contribute a considerable amount of biomass production. As an annually migrating species, silver perch export in excess of 7400 t of biomass to the near-coastal ecosystem, providing a trophic subsidy from seagrass habitats via trophic transfer.\n
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\n \n\n \n \n \n \n \n Biodiversity mediates top-down control in eelgrass ecosystems: A global comparative-experimental approach.\n \n \n \n\n\n \n Duffy, J. E.; Reynolds, P. L.; Boström, C.; Coyer, J. A.; Cusson, M.; Donadi, S.; Douglass, J. G.; Eklöf, J. S.; Engelen, A. H.; Eriksson, B. K.; Fredriksen, S.; Gamfeldt, L.; Gustafsson, C.; Hoarau, G.; Hori, M.; Hovel, K.; Iken, K.; Lefcheck, J. S.; Moksnes, P. O.; Nakaoka, M.; O'Connor, M. I.; Olsen, J. L.; Richardson, J. P.; Ruesink, J. L.; Sotka, E. E.; Thormar, J.; Whalen, M. A.; and Stachowicz, J. J.\n\n\n \n\n\n\n Ecology Letters. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{duffy_biodiversity_2015,\n\ttitle = {Biodiversity mediates top-down control in eelgrass ecosystems: {A} global comparative-experimental approach},\n\tdoi = {10.1111/ele.12448},\n\tabstract = {Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors.},\n\tjournal = {Ecology Letters},\n\tauthor = {Duffy, J. Emmett and Reynolds, Pamela L. and Boström, Christoffer and Coyer, James A. and Cusson, Mathieu and Donadi, Serena and Douglass, James G. and Eklöf, Johan S. and Engelen, Aschwin H. and Eriksson, Britas Klemens and Fredriksen, Stein and Gamfeldt, Lars and Gustafsson, Camilla and Hoarau, Galice and Hori, Masakazu and Hovel, Kevin and Iken, Katrin and Lefcheck, Jonathan S. and Moksnes, Per Olav and Nakaoka, Masahiro and O'Connor, Mary I. and Olsen, Jeanine L. and Richardson, J. Paul and Ruesink, Jennifer L. and Sotka, Erik E. and Thormar, Jonas and Whalen, Matthew A. and Stachowicz, John J.},\n\tyear = {2015},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors.\n
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\n \n\n \n \n \n \n \n Can we predict the future: Juvenile finfish and their seagrass nurseries in the Chesapeake Bay.\n \n \n \n\n\n \n Jones, C. M.\n\n\n \n\n\n\n ICES Journal of Marine Science. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{jones_can_2014,\n\ttitle = {Can we predict the future: {Juvenile} finfish and their seagrass nurseries in the {Chesapeake} {Bay}},\n\tdoi = {10.1093/icesjms/fst142},\n\tabstract = {The importance of estuarine seagrass beds as nurseries for juvenile fish has become a universal paradigm, especially for estuaries that are as important as the Chesapeake Bay. Yet, scientific tests of this hypothesis were equivocal depending on species, location, and metrics. Moreover, seagrasses themselves are under threat and one-third of seagrasses have disappeared worldwide with 65\\% of their losses occurring in estuaries. Although there have been extensive studies of seagrasses in the Chesapeake Bay, surprisingly few studies have quantified the relationship between seagrass as nurseries for finfish in the Bay. Of the few studies that have directly evaluated the use of seagrass nurseries, most have concentrated on single species or were of short duration. Few landscape-level or long-term studies have examined this relationship in the Bay or explored the potential effect of climate change. This review paper summarizes the seagrass habitat value as nurseries and presents recent juvenile fish studies that address the dearth of research at the long term and landscape level with an emphasis on the Chesapeake Bay. An important conclusion upon the review of these studies is that predicting the effects of climate change on fishery production remains uncertain. © 2013 International Council for the Exploration of the Sea.},\n\tjournal = {ICES Journal of Marine Science},\n\tauthor = {Jones, Cynthia M.},\n\tyear = {2014},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n The importance of estuarine seagrass beds as nurseries for juvenile fish has become a universal paradigm, especially for estuaries that are as important as the Chesapeake Bay. Yet, scientific tests of this hypothesis were equivocal depending on species, location, and metrics. Moreover, seagrasses themselves are under threat and one-third of seagrasses have disappeared worldwide with 65% of their losses occurring in estuaries. Although there have been extensive studies of seagrasses in the Chesapeake Bay, surprisingly few studies have quantified the relationship between seagrass as nurseries for finfish in the Bay. Of the few studies that have directly evaluated the use of seagrass nurseries, most have concentrated on single species or were of short duration. Few landscape-level or long-term studies have examined this relationship in the Bay or explored the potential effect of climate change. This review paper summarizes the seagrass habitat value as nurseries and presents recent juvenile fish studies that address the dearth of research at the long term and landscape level with an emphasis on the Chesapeake Bay. An important conclusion upon the review of these studies is that predicting the effects of climate change on fishery production remains uncertain. © 2013 International Council for the Exploration of the Sea.\n
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\n \n\n \n \n \n \n \n Epifaunal invertebrates as predators of juvenile bay scallops (Argopecten irradians).\n \n \n \n\n\n \n Lefcheck, J. S.; van Montfrans, J.; Orth, R. J.; Schmitt, E. L.; Duffy, J. E.; and Luckenbach, M. W.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{lefcheck_epifaunal_2014,\n\ttitle = {Epifaunal invertebrates as predators of juvenile bay scallops ({Argopecten} irradians)},\n\tdoi = {10.1016/j.jembe.2014.01.014},\n\tabstract = {Predation strongly influences populations of numerous benthic invertebrates, although many predation studies to date have focused on macroscopic individuals, ignoring critical early life stages. Juveniles of the bay scallop, Argopecten irradians, settle and grow on the blades of eelgrass, Zostera marina, then migrate to the sediment surface when their mobility and size provide a refuge from benthic predators. During their time in the eelgrass canopy, scallops co-occur with a diverse array of small invertebrates, including peracarid and small decapod crustaceans, whose role as predators is largely unexplored. We measured consumption by amphipods, isopods, and a shrimp on recently settled bay scallops ranging in size from 0.5 to {\\textbackslash}textgreater1.5mm in a series of 24-hour experimental laboratory assays. These invertebrate predators, which were common concurrent epifaunal surveys of restored eelgrass beds in the mid-Atlantic, consumed up to 63\\% day-1 of juvenile scallops when the scallops were {\\textbackslash}textless1mm, but predation impacts decreased as scallops exceeded this size. Our data have implications for current restoration of both bay scallops and their eelgrass habitat, suggesting that previously unrecognized consumers may significantly affect scallop population dynamics at early life stages. © 2014 Elsevier B.V.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Lefcheck, Jonathan S. and van Montfrans, Jacques and Orth, Robert J. and Schmitt, Erika L. and Duffy, J. Emmett and Luckenbach, Mark W.},\n\tyear = {2014},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n Predation strongly influences populations of numerous benthic invertebrates, although many predation studies to date have focused on macroscopic individuals, ignoring critical early life stages. Juveniles of the bay scallop, Argopecten irradians, settle and grow on the blades of eelgrass, Zostera marina, then migrate to the sediment surface when their mobility and size provide a refuge from benthic predators. During their time in the eelgrass canopy, scallops co-occur with a diverse array of small invertebrates, including peracarid and small decapod crustaceans, whose role as predators is largely unexplored. We measured consumption by amphipods, isopods, and a shrimp on recently settled bay scallops ranging in size from 0.5 to \\textgreater1.5mm in a series of 24-hour experimental laboratory assays. These invertebrate predators, which were common concurrent epifaunal surveys of restored eelgrass beds in the mid-Atlantic, consumed up to 63% day-1 of juvenile scallops when the scallops were \\textless1mm, but predation impacts decreased as scallops exceeded this size. Our data have implications for current restoration of both bay scallops and their eelgrass habitat, suggesting that previously unrecognized consumers may significantly affect scallop population dynamics at early life stages. © 2014 Elsevier B.V.\n
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\n \n\n \n \n \n \n \n Patterns of seagrass community response to local shoreline development.\n \n \n \n\n\n \n Blake, R. E.; Duffy, J. E.; and Richardson, J. P.\n\n\n \n\n\n\n Estuaries and Coasts. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{blake_patterns_2014,\n\ttitle = {Patterns of seagrass community response to local shoreline development},\n\tdoi = {10.1007/s12237-014-9784-7},\n\tabstract = {Three quarters of the global human population will live in coastal areas in the coming decades and will continue to develop these areas as population density increases. Anthropogenic stressors from this coastal development may lead to fragmented habitats, altered food webs, changes in sediment characteristics, and loss of near-shore vegetated habitats. Seagrass systems are important vegetated estuarine habitats that are vulnerable to anthropogenic stressors, but provide valuable ecosystem functions. Key to maintaining these habitats that filter water, stabilize sediments, and provide refuge to juvenile animals is an understanding of the impacts of local coastal development. To assess development impacts in seagrass communities, we surveyed 20 seagrass beds in lower Chesapeake Bay, VA. We sampled primary producers, consumers, water quality, and sediment characteristics in seagrass beds, and characterized development along the adjacent shoreline using land cover data. Overall, we could not detect effects of local coastal development on these seagrass communities. Seagrass biomass varied only between sites, and was positively correlated with sediment organic matter. Epiphytic algal biomass and epibiont (epifauna and epiphyte) community composition varied between western and eastern regions of the bay. But, neither eelgrass (Zostera marina) leaf nitrogen (a proxy for integrated nitrogen loading), crustacean grazer biomass, epifaunal predator abundance, nor fish and crab abundance differed significantly among sites or regions. Overall, factors operating on different scales appear to drive primary producers, seagrass-associated faunal communities, and sediment properties in these important submerged vegetated habitats in lower Chesapeake Bay.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Blake, Rachael E. and Duffy, J. Emmett and Richardson, J. Paul},\n\tyear = {2014},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Three quarters of the global human population will live in coastal areas in the coming decades and will continue to develop these areas as population density increases. Anthropogenic stressors from this coastal development may lead to fragmented habitats, altered food webs, changes in sediment characteristics, and loss of near-shore vegetated habitats. Seagrass systems are important vegetated estuarine habitats that are vulnerable to anthropogenic stressors, but provide valuable ecosystem functions. Key to maintaining these habitats that filter water, stabilize sediments, and provide refuge to juvenile animals is an understanding of the impacts of local coastal development. To assess development impacts in seagrass communities, we surveyed 20 seagrass beds in lower Chesapeake Bay, VA. We sampled primary producers, consumers, water quality, and sediment characteristics in seagrass beds, and characterized development along the adjacent shoreline using land cover data. Overall, we could not detect effects of local coastal development on these seagrass communities. Seagrass biomass varied only between sites, and was positively correlated with sediment organic matter. Epiphytic algal biomass and epibiont (epifauna and epiphyte) community composition varied between western and eastern regions of the bay. But, neither eelgrass (Zostera marina) leaf nitrogen (a proxy for integrated nitrogen loading), crustacean grazer biomass, epifaunal predator abundance, nor fish and crab abundance differed significantly among sites or regions. Overall, factors operating on different scales appear to drive primary producers, seagrass-associated faunal communities, and sediment properties in these important submerged vegetated habitats in lower Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Evidence of eelgrass (Zostera marina) seed dispersal by northern diamondback terrapin (Malaclemys terrapin terrapin) in lower Chesapeake Bay.\n \n \n \n\n\n \n Tulipani, D. C.; and Lipcius, R. N.\n\n\n \n\n\n\n PLoS ONE. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{tulipani_evidence_2014,\n\ttitle = {Evidence of eelgrass ({Zostera} marina) seed dispersal by northern diamondback terrapin ({Malaclemys} terrapin terrapin) in lower {Chesapeake} {Bay}},\n\tdoi = {10.1371/journal.pone.0103346},\n\tabstract = {The initial discovery in May 2009 of eelgrass (Zostera marina) seeds in fecal samples of wild-caught northern diamondback terrapins ( Malaclemys terrapin terrapin) was the first field evidence of eelgrass seed ingestion in this species. This finding suggested the potential of terrapins as seed dispersers in eelgrass beds, which we sampled for two additional years (2010 and 2011). Seeds were only found in feces of terrapins captured prior to June 8 in all three years, coinciding with eelgrass seed maturation and release. Numbers of seeds in terrapin feces varied annually and decreased greatly in 2011 after an eelgrass die off in late 2010. The condition of seeds in terrapin feces was viable-mature, germinated, damaged, or immature. Of terrapins captured during time of seed release, 97\\% were males and juvenile females, both of which had head widths {\\textbackslash}textless 30 mm. The fraction of individuals with ingested seeds was 33\\% for males, 35\\% for small females, and only 6\\% for large (mature) females. Probability of seed ingestion decreased exponentially with increasing terrapin head width; only males and small females (head width {\\textbackslash}textless30 mm) were likely to be vectors of seed dispersal. The characteristic that diamondback terrapins have well-defined home ranges allowed us to estimate the number of terrapins potentially dispersing eelgrass seeds annually. In seagrass beds of the Goodwin Islands region (lower York River, Virginia), there were 559 to 799 terrapins, which could disperse between 1,341 and 1,677 eelgrass seeds annually. These would represent a small proportion of total seed production within a single seagrass bed. However, based on probable home range distances, terrapins can easily traverse eelgrass meadow boundaries, thereby dispersing seeds beyond the bed of origin. Given the relatively short dispersion distance of eelgrass seeds, the diamondback terrapin may be a major source of inter-bed seed dispersal and genetic diversity. © 2014 Tulipani, Lipcius.},\n\tjournal = {PLoS ONE},\n\tauthor = {Tulipani, Diane C. and Lipcius, Romuald N.},\n\tyear = {2014},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The initial discovery in May 2009 of eelgrass (Zostera marina) seeds in fecal samples of wild-caught northern diamondback terrapins ( Malaclemys terrapin terrapin) was the first field evidence of eelgrass seed ingestion in this species. This finding suggested the potential of terrapins as seed dispersers in eelgrass beds, which we sampled for two additional years (2010 and 2011). Seeds were only found in feces of terrapins captured prior to June 8 in all three years, coinciding with eelgrass seed maturation and release. Numbers of seeds in terrapin feces varied annually and decreased greatly in 2011 after an eelgrass die off in late 2010. The condition of seeds in terrapin feces was viable-mature, germinated, damaged, or immature. Of terrapins captured during time of seed release, 97% were males and juvenile females, both of which had head widths \\textless 30 mm. The fraction of individuals with ingested seeds was 33% for males, 35% for small females, and only 6% for large (mature) females. Probability of seed ingestion decreased exponentially with increasing terrapin head width; only males and small females (head width \\textless30 mm) were likely to be vectors of seed dispersal. The characteristic that diamondback terrapins have well-defined home ranges allowed us to estimate the number of terrapins potentially dispersing eelgrass seeds annually. In seagrass beds of the Goodwin Islands region (lower York River, Virginia), there were 559 to 799 terrapins, which could disperse between 1,341 and 1,677 eelgrass seeds annually. These would represent a small proportion of total seed production within a single seagrass bed. However, based on probable home range distances, terrapins can easily traverse eelgrass meadow boundaries, thereby dispersing seeds beyond the bed of origin. Given the relatively short dispersion distance of eelgrass seeds, the diamondback terrapin may be a major source of inter-bed seed dispersal and genetic diversity. © 2014 Tulipani, Lipcius.\n
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\n \n\n \n \n \n \n \n Historical Comparison of Fish Community Structure in Lower Chesapeake Bay Seagrass Habitats.\n \n \n \n\n\n \n Sobocinski, K. L.; Orth, R. J.; Fabrizio, M. C.; and Latour, R. J.\n\n\n \n\n\n\n Estuaries and Coasts. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{sobocinski_historical_2013,\n\ttitle = {Historical {Comparison} of {Fish} {Community} {Structure} in {Lower} {Chesapeake} {Bay} {Seagrass} {Habitats}},\n\tdoi = {10.1007/s12237-013-9586-3},\n\tabstract = {Seagrass beds provide important habitat for fishes and invertebrates in many regions around the world. Accordingly, changes in seagrass coverage may affect fish communities and/or populations, given that many species utilize these habitats during vulnerable early life history stages. In lower Chesapeake Bay, seagrass distribution has contracted appreciably over recent decades due to decreased water clarity and increased water temperature; however, effects of changing vegetated habitat on fish community structure have not been well documented. We compared fish community composition data collected at similar seagrass sites from 1976-1977 and 2009-2011 to investigate potential changes in species richness, community composition, and relative abundance within these habitats. While seagrass coverage at the specific study sites did not vary considerably between time periods, contemporary species richness was lower and multivariate analysis showed that assemblages differed between the two datasets. The majority of sampled species were common to both datasets but several species were exclusive to only one dataset. For some species, relative abundances were similar between the two datasets, while for others, there were notable differences without directional uniformity. Spot (Leiostomus xanthurus) and northern pipefish (Syngnathus fuscus) were considerably less abundant in the contemporary dataset, while dusky pipefish (Syngnathus floridae) was more abundant. Observed changes in community structure may be more attributable to higher overall bay water temperature in recent years and other anthropogenic influences than to changes in seagrass coverage at our study sites. © 2013 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Sobocinski, Kathryn L. and Orth, Robert J. and Fabrizio, Mary C. and Latour, Robert J.},\n\tyear = {2013},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Seagrass beds provide important habitat for fishes and invertebrates in many regions around the world. Accordingly, changes in seagrass coverage may affect fish communities and/or populations, given that many species utilize these habitats during vulnerable early life history stages. In lower Chesapeake Bay, seagrass distribution has contracted appreciably over recent decades due to decreased water clarity and increased water temperature; however, effects of changing vegetated habitat on fish community structure have not been well documented. We compared fish community composition data collected at similar seagrass sites from 1976-1977 and 2009-2011 to investigate potential changes in species richness, community composition, and relative abundance within these habitats. While seagrass coverage at the specific study sites did not vary considerably between time periods, contemporary species richness was lower and multivariate analysis showed that assemblages differed between the two datasets. The majority of sampled species were common to both datasets but several species were exclusive to only one dataset. For some species, relative abundances were similar between the two datasets, while for others, there were notable differences without directional uniformity. Spot (Leiostomus xanthurus) and northern pipefish (Syngnathus fuscus) were considerably less abundant in the contemporary dataset, while dusky pipefish (Syngnathus floridae) was more abundant. Observed changes in community structure may be more attributable to higher overall bay water temperature in recent years and other anthropogenic influences than to changes in seagrass coverage at our study sites. © 2013 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Seed burial in eelgrass Zostera marina: The role of infauna.\n \n \n \n\n\n \n Blackburn, N. J.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{blackburn_seed_2013,\n\ttitle = {Seed burial in eelgrass {Zostera} marina: {The} role of infauna},\n\tdoi = {10.3354/meps10103},\n\tabstract = {Seed burial is a vital process that influences small- and large-scale plant population patterns and is frequently mediated by soil-dwelling invertebrates. Despite its importance in terrestrial systems, very little is known about seed burial in seagrasses. The goal of this work was to determine the role that benthic infauna play in the burial of Zostera marina seeds. Mesocosm experiments studying seed burial depth, seed burial rate, and particle burial and redistribution using beads, were conducted in defaunated sediment cores populated with single specimens of infauna with different modes of feeding and thus bioturbation effects: Amphitrite ornata (downward conveyor deposit feeder), Clymenella torquata and Pectinaria gouldi (upward conveyor deposit feeders), and Neanthes succinea (gallery biodiffuser). Seeds and beads in animal cores were significantly more likely to be buried than seeds in control cores in each experiment, although burial depths and rates varied by species. N. succinea and P. gouldi showed the most dramatic burial. N. succinea also showed evidence for actively burying seeds. Seed burial depths for A. ornata, C. torquata, and P. gouldi related well to individual bioturbation rates for those species. These results indicate that Z. marina seed burial is facilitated by infaunal bioturbation. Further, individual species have a different impact on burial patterns, and burial is rapid and occurs within days. Seed burial by infaunal bioturbation is relevant to seed survival by providing escape from predation, retention in suitable settlement sites, and movement to a sediment depth suitable for germination. © Inter-Research 2013.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Blackburn, Natalia J. and Orth, Robert J.},\n\tyear = {2013},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Seed burial is a vital process that influences small- and large-scale plant population patterns and is frequently mediated by soil-dwelling invertebrates. Despite its importance in terrestrial systems, very little is known about seed burial in seagrasses. The goal of this work was to determine the role that benthic infauna play in the burial of Zostera marina seeds. Mesocosm experiments studying seed burial depth, seed burial rate, and particle burial and redistribution using beads, were conducted in defaunated sediment cores populated with single specimens of infauna with different modes of feeding and thus bioturbation effects: Amphitrite ornata (downward conveyor deposit feeder), Clymenella torquata and Pectinaria gouldi (upward conveyor deposit feeders), and Neanthes succinea (gallery biodiffuser). Seeds and beads in animal cores were significantly more likely to be buried than seeds in control cores in each experiment, although burial depths and rates varied by species. N. succinea and P. gouldi showed the most dramatic burial. N. succinea also showed evidence for actively burying seeds. Seed burial depths for A. ornata, C. torquata, and P. gouldi related well to individual bioturbation rates for those species. These results indicate that Z. marina seed burial is facilitated by infaunal bioturbation. Further, individual species have a different impact on burial patterns, and burial is rapid and occurs within days. Seed burial by infaunal bioturbation is relevant to seed survival by providing escape from predation, retention in suitable settlement sites, and movement to a sediment depth suitable for germination. © Inter-Research 2013.\n
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\n \n\n \n \n \n \n \n Temporal shifts in top-down vs. bottom-up control of epiphytic algae in a seagrass ecosystem.\n \n \n \n\n\n \n Whalen, M. A.; Duffy, J. E.; and Grace, J. B.\n\n\n \n\n\n\n Ecology. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{whalen_temporal_2013,\n\ttitle = {Temporal shifts in top-down vs. bottom-up control of epiphytic algae in a seagrass ecosystem},\n\tdoi = {10.1890/12-0156.1},\n\tabstract = {In coastal marine food webs, small invertebrate herbivores (mesograzers) have long been hypothesized to occupy an important position facilitating dominance of habitatforming macrophytes by grazing competitively superior epiphytic algae. Because of the difficulty of manipulating mesograzers in the field, however, their impacts on community organization have rarely been rigorously documented. Understanding mesograzer impacts has taken on increased urgency in seagrass systems due to declines in seagrasses globally, caused in part by widespread eutrophication favoring seagrass overgrowth by faster-growing algae. Using cage-free field experiments in two seasons (fall and summer), we present experimental confirmation that mesograzer reduction and nutrients can promote blooms of epiphytic algae growing on eelgrass (Zostera marina). In this study, nutrient additions increased epiphytes only in the fall following natural decline of mesograzers. In the summer, experimental mesograzer reduction stimulated a 447\\% increase in epiphytes, appearing to exacerbate seasonal dieback of eelgrass. Using structural equation modeling, we illuminate the temporal dynamics of complex interactions between macrophytes, mesograzers, and epiphytes in the summer experiment. An unexpected result emerged from investigating the interaction network: drift macroalgae indirectly reduced epiphytes by providing structure for mesograzers, suggesting that the net effect of macroalgae on seagrass depends on macroalgal density. Our results show that mesograzers can control proliferation of epiphytic algae, that top-down and bottom-up forcing are temporally variable, and that the presence of macroalgae can strengthen top-down control of epiphytic algae, potentially contributing to eelgrass persistence. © 2013 by the Ecological Society of America.},\n\tjournal = {Ecology},\n\tauthor = {Whalen, Matthew A. and Duffy, J. Emmett and Grace, James B.},\n\tyear = {2013},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n In coastal marine food webs, small invertebrate herbivores (mesograzers) have long been hypothesized to occupy an important position facilitating dominance of habitatforming macrophytes by grazing competitively superior epiphytic algae. Because of the difficulty of manipulating mesograzers in the field, however, their impacts on community organization have rarely been rigorously documented. Understanding mesograzer impacts has taken on increased urgency in seagrass systems due to declines in seagrasses globally, caused in part by widespread eutrophication favoring seagrass overgrowth by faster-growing algae. Using cage-free field experiments in two seasons (fall and summer), we present experimental confirmation that mesograzer reduction and nutrients can promote blooms of epiphytic algae growing on eelgrass (Zostera marina). In this study, nutrient additions increased epiphytes only in the fall following natural decline of mesograzers. In the summer, experimental mesograzer reduction stimulated a 447% increase in epiphytes, appearing to exacerbate seasonal dieback of eelgrass. Using structural equation modeling, we illuminate the temporal dynamics of complex interactions between macrophytes, mesograzers, and epiphytes in the summer experiment. An unexpected result emerged from investigating the interaction network: drift macroalgae indirectly reduced epiphytes by providing structure for mesograzers, suggesting that the net effect of macroalgae on seagrass depends on macroalgal density. Our results show that mesograzers can control proliferation of epiphytic algae, that top-down and bottom-up forcing are temporally variable, and that the presence of macroalgae can strengthen top-down control of epiphytic algae, potentially contributing to eelgrass persistence. © 2013 by the Ecological Society of America.\n
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\n \n\n \n \n \n \n \n Broad-scale association between seagrass cover and juvenile blue crab density in Chesapeake Bay.\n \n \n \n\n\n \n Ralph, G. M.; Seitz, R. D.; Orth, R. J.; Knick, K. E.; and Lipcius, R. N.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ralph_broad-scale_2013,\n\ttitle = {Broad-scale association between seagrass cover and juvenile blue crab density in {Chesapeake} {Bay}},\n\tdoi = {10.3354/meps10417},\n\tabstract = {Although numerous small-scale laboratory, mesocosm, and field experiments have demonstrated that abundance, survival, and growth of juvenile fish and invertebrates are higher in vegetated than in unvegetated habitats, the effect of habitat quality (i.e. habitat complexity) within vegetated habitats has not been documented at a broad spatial scale. We examined the relationship between percent cover in seagrass beds (eelgrass Zostera marina, widgeon grass Ruppia maritima, and associated macroalgae) and juvenile blue crab Callinectes sapidus density at a broad spatial scale. We quantified the functional relationship between juvenile density and percent cover of vegetation by sampling in Chesapeake Bay (USA) seagrass beds utilized by juvenile blue crabs in the fall of 2007 and 2008, following peak postlarval blue crab recruitment. Based on Akaike's information criterion model comparisons, the most plausible model included both percent cover of vegetation and region of Chesapeake Bay. Juvenile crab density was a positive exponential function of percent cover of vegetation, and was augmented by 14 to 30\\%, depending on year, for every 10\\% increase in cover. Density was approximately 2 times higher on the western shore of Chesapeake Bay than on the eastern shore. Seagrass bed area, presence or absence of algae, and distance to the mouth of the bay did not significantly influence density. An expected threshold (i.e. sigmoid) response of juvenile density to percent cover of vegetation was not evident, probably because this study was undertaken when recruitment was low, so habitats may not have been at carrying capacity. This study is the first to document the functional relationship between habitat quality and juvenile density at a broad spatial scale for a marine fish or invertebrate, and suggests that the quality of seagrass habitat influences population dynamics. © Inter-Research 2013.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Ralph, Gina M. and Seitz, Rochelle D. and Orth, Robert J. and Knick, Kathleen E. and Lipcius, Romuald N.},\n\tyear = {2013},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Although numerous small-scale laboratory, mesocosm, and field experiments have demonstrated that abundance, survival, and growth of juvenile fish and invertebrates are higher in vegetated than in unvegetated habitats, the effect of habitat quality (i.e. habitat complexity) within vegetated habitats has not been documented at a broad spatial scale. We examined the relationship between percent cover in seagrass beds (eelgrass Zostera marina, widgeon grass Ruppia maritima, and associated macroalgae) and juvenile blue crab Callinectes sapidus density at a broad spatial scale. We quantified the functional relationship between juvenile density and percent cover of vegetation by sampling in Chesapeake Bay (USA) seagrass beds utilized by juvenile blue crabs in the fall of 2007 and 2008, following peak postlarval blue crab recruitment. Based on Akaike's information criterion model comparisons, the most plausible model included both percent cover of vegetation and region of Chesapeake Bay. Juvenile crab density was a positive exponential function of percent cover of vegetation, and was augmented by 14 to 30%, depending on year, for every 10% increase in cover. Density was approximately 2 times higher on the western shore of Chesapeake Bay than on the eastern shore. Seagrass bed area, presence or absence of algae, and distance to the mouth of the bay did not significantly influence density. An expected threshold (i.e. sigmoid) response of juvenile density to percent cover of vegetation was not evident, probably because this study was undertaken when recruitment was low, so habitats may not have been at carrying capacity. This study is the first to document the functional relationship between habitat quality and juvenile density at a broad spatial scale for a marine fish or invertebrate, and suggests that the quality of seagrass habitat influences population dynamics. © Inter-Research 2013.\n
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\n \n\n \n \n \n \n \n Fish Species Distribution in Seagrass Habitats of Chesapeake Bay are Structured by Abiotic and Biotic Factors.\n \n \n \n\n\n \n Schaffler, J. J.; van Montfrans, J.; Jones, C. M.; and Orth, R. J.\n\n\n \n\n\n\n Marine and Coastal Fisheries. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{schaffler_fish_2013,\n\ttitle = {Fish {Species} {Distribution} in {Seagrass} {Habitats} of {Chesapeake} {Bay} are {Structured} by {Abiotic} and {Biotic} {Factors}},\n\tdoi = {10.1080/19425120.2013.804013},\n\tabstract = {Seagrass habitats have long been known to serve as nursery habitats for juvenile fish by providing refuges from predation and areas of high forage abundance. However, comparatively less is known about other factors structuring fish communities that make extensive use of seagrass as nursery habitat. We examined both physical and biological factors that may structure the juvenile seagrass-associated fish communities across a synoptic-scale multiyear study in lower Chesapeake Bay. Across 3 years of sampling, we collected 21,153 fish from 31 species. Silver Perch Bairdiella chrysoura made up over 86\\% of all individuals collected. Nine additional species made up at least 1\\% of the fish community in the bay but were at very different abundances than historical estimates of the fish community from the early 1980s. Eight species, including Silver Perch, showed a relationship with measured gradients of temperature or salinity and Spot Leiostomus xanthurus showed a negative relationship with the presence of macroalgae. Climate change, particularly increased precipitation and runoff from frequent and intense events, has the potential to alter fish-habitat relationships in seagrass beds and other habitats and may have already altered the fish community composition. Comparisons of fish species to historical data from the 1970s, our data, and recent contemporary data in the late 2000s suggests this has occurred. Received September 4, 2012; accepted May 5, 2013. © 2013 Copyright Taylor and Francis Group, LLC.},\n\tjournal = {Marine and Coastal Fisheries},\n\tauthor = {Schaffler, Jason J. and van Montfrans, Jacques and Jones, Cynthia M. and Orth, Robert J.},\n\tyear = {2013},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Seagrass habitats have long been known to serve as nursery habitats for juvenile fish by providing refuges from predation and areas of high forage abundance. However, comparatively less is known about other factors structuring fish communities that make extensive use of seagrass as nursery habitat. We examined both physical and biological factors that may structure the juvenile seagrass-associated fish communities across a synoptic-scale multiyear study in lower Chesapeake Bay. Across 3 years of sampling, we collected 21,153 fish from 31 species. Silver Perch Bairdiella chrysoura made up over 86% of all individuals collected. Nine additional species made up at least 1% of the fish community in the bay but were at very different abundances than historical estimates of the fish community from the early 1980s. Eight species, including Silver Perch, showed a relationship with measured gradients of temperature or salinity and Spot Leiostomus xanthurus showed a negative relationship with the presence of macroalgae. Climate change, particularly increased precipitation and runoff from frequent and intense events, has the potential to alter fish-habitat relationships in seagrass beds and other habitats and may have already altered the fish community composition. Comparisons of fish species to historical data from the 1970s, our data, and recent contemporary data in the late 2000s suggests this has occurred. Received September 4, 2012; accepted May 5, 2013. © 2013 Copyright Taylor and Francis Group, LLC.\n
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\n \n\n \n \n \n \n \n Changes in biodiversity and environmental stressors influence community structure of an experimental eelgrass Zostera marina system.\n \n \n \n\n\n \n Blake, R. E.; and Duffy, J. E.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{blake_changes_2012,\n\ttitle = {Changes in biodiversity and environmental stressors influence community structure of an experimental eelgrass {Zostera} marina system},\n\tdoi = {10.3354/meps10006},\n\tabstract = {Changes in biodiversity can result in decreased ecosystem functioning and loss of ecosystem services, but altered biodiversity is only one of many stressors impacting ecosystems. In many estuaries, environmental stressors such as warming water temperatures and eutrophication are increasing and negatively impacting biological communities, particularly seagrasses such as the important habitat-forming species Zostera marina (eelgrass). These negative impacts may change the diversity, composition, and functioning of this important ecosystem, but the interactions of stressors with changes in biodiversity are poorly understood. We manipulated eelgrass communities in a factorial experiment to test how changes in crustacean grazer diversity, warmer water temperatures, and nutrient enrichment interact to affect ecosystem biomass, stability, and community composition. We found that the presence and richness of crustacean grazers had a larger effect on grazer, algal, and sessile invertebrate biomass than experimental warming or nutrient enrichment. Diverse grazer assemblages stabilized epiphytic algal biomass in the face of stressors, and counteracted the promotion of epiphytic microalgae by stressors. Nutrient enrichment and warming both promoted epiphytic microalgae, while reducing macroalgae and eelgrass. A more diverse grazer assemblage stabilized epiphytic algal biomass, but we did not detect interactions among environmental stressors and grazer diversity. These results emphasize that loss of herbivore diversity can exacerbate the impacts of environmental stressors on grazing, relative dominance of microalgae versus macrophytes, producer biomass, and stability. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Blake, Rachael E. and Duffy, J. Emmett},\n\tyear = {2012},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Changes in biodiversity can result in decreased ecosystem functioning and loss of ecosystem services, but altered biodiversity is only one of many stressors impacting ecosystems. In many estuaries, environmental stressors such as warming water temperatures and eutrophication are increasing and negatively impacting biological communities, particularly seagrasses such as the important habitat-forming species Zostera marina (eelgrass). These negative impacts may change the diversity, composition, and functioning of this important ecosystem, but the interactions of stressors with changes in biodiversity are poorly understood. We manipulated eelgrass communities in a factorial experiment to test how changes in crustacean grazer diversity, warmer water temperatures, and nutrient enrichment interact to affect ecosystem biomass, stability, and community composition. We found that the presence and richness of crustacean grazers had a larger effect on grazer, algal, and sessile invertebrate biomass than experimental warming or nutrient enrichment. Diverse grazer assemblages stabilized epiphytic algal biomass in the face of stressors, and counteracted the promotion of epiphytic microalgae by stressors. Nutrient enrichment and warming both promoted epiphytic microalgae, while reducing macroalgae and eelgrass. A more diverse grazer assemblage stabilized epiphytic algal biomass, but we did not detect interactions among environmental stressors and grazer diversity. These results emphasize that loss of herbivore diversity can exacerbate the impacts of environmental stressors on grazing, relative dominance of microalgae versus macrophytes, producer biomass, and stability. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Biotic dispersal in eelgrass Zostera marina.\n \n \n \n\n\n \n Sumoski, S. E.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{sumoski_biotic_2012,\n\ttitle = {Biotic dispersal in eelgrass {Zostera} marina},\n\tdoi = {10.3354/meps10145},\n\tabstract = {Dispersal is a critical process in the life history of nearly all plant species and can be facilitated by both abiotic and biotic mechanisms. Despite an abundance of vertebrate fauna utilizing seagrass meadows as a feeding area and thus capable of consuming and excreting seeds, little work has been conducted on biotic seed dispersal mechanisms. The objectives of this study were to (1) determine whether seeds of the seagrass Zostera marina could pass through the digestive systems of resident and transient vertebrates of a seagrass bed and remain viable and (2) determine seed retention times in the guts of each species to estimate dispersal distances of Z. marina seeds by vertebrate dispersers. Excretion and germination rates of consumed seeds for 3 fish species (Fundulus heteroclitus, Sphoeroides maculatus, Lagodon rhomboides), 1 turtle species (Malaclemys terrapin) and 1 waterfowl species (Aythya affinis) showed Z. marina seeds could survive passage through species' digestive systems and successfully germinate. Excretion rates were generally highest for F. heteroclitus, S. maculatus, and M. terrapin, lowest for A. affinis, and moderate for L. rhomboides. Analyses suggest seeds were significantly affected by species' digestive tracts. Maximum dispersal distances are estimated to be 200, 60, 1500, and 19 500 m for F. heteroclitus, L. rhomboides, M. terrapin, and A. affinis, respectively. Data here provide strong evidence that biotic dispersal can occur in Z. marina, and biotically transported seeds can be dispersed to isolated areas unlikely to receive seeds via abiotic mechanisms. Biotic dispersal may rival or exceed abiotic mechanisms. Future seagrass dispersal models should incorporate biotic dispersal as a seed transport mechanism. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Sumoski, Sarah E. and Orth, Robert J.},\n\tyear = {2012},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Dispersal is a critical process in the life history of nearly all plant species and can be facilitated by both abiotic and biotic mechanisms. Despite an abundance of vertebrate fauna utilizing seagrass meadows as a feeding area and thus capable of consuming and excreting seeds, little work has been conducted on biotic seed dispersal mechanisms. The objectives of this study were to (1) determine whether seeds of the seagrass Zostera marina could pass through the digestive systems of resident and transient vertebrates of a seagrass bed and remain viable and (2) determine seed retention times in the guts of each species to estimate dispersal distances of Z. marina seeds by vertebrate dispersers. Excretion and germination rates of consumed seeds for 3 fish species (Fundulus heteroclitus, Sphoeroides maculatus, Lagodon rhomboides), 1 turtle species (Malaclemys terrapin) and 1 waterfowl species (Aythya affinis) showed Z. marina seeds could survive passage through species' digestive systems and successfully germinate. Excretion rates were generally highest for F. heteroclitus, S. maculatus, and M. terrapin, lowest for A. affinis, and moderate for L. rhomboides. Analyses suggest seeds were significantly affected by species' digestive tracts. Maximum dispersal distances are estimated to be 200, 60, 1500, and 19 500 m for F. heteroclitus, L. rhomboides, M. terrapin, and A. affinis, respectively. Data here provide strong evidence that biotic dispersal can occur in Z. marina, and biotically transported seeds can be dispersed to isolated areas unlikely to receive seeds via abiotic mechanisms. Biotic dispersal may rival or exceed abiotic mechanisms. Future seagrass dispersal models should incorporate biotic dispersal as a seed transport mechanism. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Spectral signatures of hydrilla from a tank and field setting.\n \n \n \n\n\n \n Blanco, A.; Qu, J. J.; and Roper, W. E.\n\n\n \n\n\n\n Frontiers of Earth Science. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{blanco_spectral_2012,\n\ttitle = {Spectral signatures of hydrilla from a tank and field setting},\n\tdoi = {10.1007/s11707-012-0331-1},\n\tabstract = {The invasion of hydrilla in many waterways has caused significant problems resulting in high maintenance costs for eradicating this invasive aquatic weed. Present identification methods employed for detecting hydrilla invasions such as aerial photography and videos are difficult, costly, and time consuming. Remote sensing has been used for assessing wetlands and other aquatic vegetation, but very little information is available for detecting hydrilla invasions in coastal estuaries and other water bodies. The objective of this study is to construct a library of spectral signatures for identifying and classifying hydrilla invasions. Spectral signatures of hydrilla were collected from an experimental tank and field locations in a coastal estuary in the upper Chesapeake Bay. These measurements collected from the experimental tank, resulted in spectral signatures with an average peak surface reflectance in the near-infrared (NIR) region of 16\\% at a wavelength of 818 nm. However, the spectral measurements, collected in the estuary, resulted in a very different spectral signature with two surface reflectance peaks of 6\\% at wavelengths of 725 nm and 818 nm. The difference in spectral signatures between sites are a result of the components in the water column in the estuary because of increased turbidity (e. g., nutrients, dissolved matter and suspended matter), and canopy being lower (submerged) in the water column. Spectral signatures of hydrilla observed in the tank and the field had similar characteristics with low reflectance in visible region of the spectrum from 400 to 700 nm, but high in the NIR region from 700 to 900 nm. © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.},\n\tjournal = {Frontiers of Earth Science},\n\tauthor = {Blanco, Alfonso and Qu, John J. and Roper, William E.},\n\tyear = {2012},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The invasion of hydrilla in many waterways has caused significant problems resulting in high maintenance costs for eradicating this invasive aquatic weed. Present identification methods employed for detecting hydrilla invasions such as aerial photography and videos are difficult, costly, and time consuming. Remote sensing has been used for assessing wetlands and other aquatic vegetation, but very little information is available for detecting hydrilla invasions in coastal estuaries and other water bodies. The objective of this study is to construct a library of spectral signatures for identifying and classifying hydrilla invasions. Spectral signatures of hydrilla were collected from an experimental tank and field locations in a coastal estuary in the upper Chesapeake Bay. These measurements collected from the experimental tank, resulted in spectral signatures with an average peak surface reflectance in the near-infrared (NIR) region of 16% at a wavelength of 818 nm. However, the spectral measurements, collected in the estuary, resulted in a very different spectral signature with two surface reflectance peaks of 6% at wavelengths of 725 nm and 818 nm. The difference in spectral signatures between sites are a result of the components in the water column in the estuary because of increased turbidity (e. g., nutrients, dissolved matter and suspended matter), and canopy being lower (submerged) in the water column. Spectral signatures of hydrilla observed in the tank and the field had similar characteristics with low reflectance in visible region of the spectrum from 400 to 700 nm, but high in the NIR region from 700 to 900 nm. © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.\n
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\n \n\n \n \n \n \n \n Habitat Affects Survival of Translocated Bay Scallops, Argopecten irradians concentricus (Say 1822), in Lower Chesapeake Bay.\n \n \n \n\n\n \n Cordero, A. L.; Seitz, R. D.; Lipcius, R. N.; Bovery, C. M.; and Schulte, D. M.\n\n\n \n\n\n\n Estuaries and Coasts. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{cordero_habitat_2012,\n\ttitle = {Habitat {Affects} {Survival} of {Translocated} {Bay} {Scallops}, {Argopecten} irradians concentricus ({Say} 1822), in {Lower} {Chesapeake} {Bay}},\n\tdoi = {10.1007/s12237-012-9510-2},\n\tabstract = {Bay scallop (Argopecten irradians) populations existed in Chesapeake Bay until 1933, when they declined dramatically due to a loss of seagrass habitat. Since then, there have been no documented populations within the Bay. However, some anecdotal observations of live bay scallops within the lower Bay suggest that restoration of the bay scallop is feasible. We therefore tested whether translocated adults of the southern bay scallop, Argopecten irradians concentricus, could survive during the reproductive season in vegetated and unvegetated habitats of the Lynnhaven River sub-estuary of lower Chesapeake Bay in the absence of predation. Manipulative field experiments evaluated survival of translocated, caged adult scallops in eelgrass Zostera marina, macroalgae Gracilaria spp., oyster shell, and rubble plots at three locations. After a 3-week experimental period, scallop survival was high in vegetated habitats, ranging from 98\\% in their preferred habitat, Z. marina, to 90\\% in Gracilaria spp. Survival in Z. marina was significantly higher than that in rubble (76\\%) and oyster shell (78\\%). These findings indicate that reproductive individuals can survive in vegetated habitats of lower Chesapeake Bay when protected from predators and that establishment of bay scallop populations within Chesapeake Bay may be viable. © 2012 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Cordero, Ana L.Hernández and Seitz, Rochelle D. and Lipcius, Romuald N. and Bovery, Caitlin M. and Schulte, David M.},\n\tyear = {2012},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Bay scallop (Argopecten irradians) populations existed in Chesapeake Bay until 1933, when they declined dramatically due to a loss of seagrass habitat. Since then, there have been no documented populations within the Bay. However, some anecdotal observations of live bay scallops within the lower Bay suggest that restoration of the bay scallop is feasible. We therefore tested whether translocated adults of the southern bay scallop, Argopecten irradians concentricus, could survive during the reproductive season in vegetated and unvegetated habitats of the Lynnhaven River sub-estuary of lower Chesapeake Bay in the absence of predation. Manipulative field experiments evaluated survival of translocated, caged adult scallops in eelgrass Zostera marina, macroalgae Gracilaria spp., oyster shell, and rubble plots at three locations. After a 3-week experimental period, scallop survival was high in vegetated habitats, ranging from 98% in their preferred habitat, Z. marina, to 90% in Gracilaria spp. Survival in Z. marina was significantly higher than that in rubble (76%) and oyster shell (78%). These findings indicate that reproductive individuals can survive in vegetated habitats of lower Chesapeake Bay when protected from predators and that establishment of bay scallop populations within Chesapeake Bay may be viable. © 2012 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Food Web Structure in a Chesapeake Bay Eelgrass Bed as Determined through Gut Contents and 13C and 15N Isotope Analysis.\n \n \n \n\n\n \n Douglass, J. G.; Emmett Duffy, J.; and Canuel, E. A.\n\n\n \n\n\n\n Estuaries and Coasts. 2011.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{douglass_food_2011,\n\ttitle = {Food {Web} {Structure} in a {Chesapeake} {Bay} {Eelgrass} {Bed} as {Determined} through {Gut} {Contents} and {13C} and {15N} {Isotope} {Analysis}},\n\tdoi = {10.1007/s12237-010-9356-4},\n\tabstract = {Changes in seagrass food-web structure can shift the competitive balance between seagrass and algae, and may alter the flow of energy from lower trophic levels to commercially important fish and crustaceans. Yet, trophic relationships in many seagrass systems remain poorly resolved. We estimated the food web linkages among small predators, invertebrate mesograzers, and primary producers in a Chesapeake Bay eelgrass (Zostera marina) bed by analyzing gut contents and stable C and N isotope ratios. Though trophic levels were relatively distinct, predators varied in the proportion of mesograzers consumed relative to alternative prey, and some mesograzers consumed macrophytes or exhibited intra-guild predation in addition to feeding on periphyton and detritus. These findings corroborate conclusions from lab and mesocosm studies that the ecological impacts of mesograzers vary widely among species, and they emphasize the need for taxonomic resolution and ecological information within seagrass epifaunal communities. © 2011 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Douglass, James G. and Emmett Duffy, J. and Canuel, Elizabeth A.},\n\tyear = {2011},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Changes in seagrass food-web structure can shift the competitive balance between seagrass and algae, and may alter the flow of energy from lower trophic levels to commercially important fish and crustaceans. Yet, trophic relationships in many seagrass systems remain poorly resolved. We estimated the food web linkages among small predators, invertebrate mesograzers, and primary producers in a Chesapeake Bay eelgrass (Zostera marina) bed by analyzing gut contents and stable C and N isotope ratios. Though trophic levels were relatively distinct, predators varied in the proportion of mesograzers consumed relative to alternative prey, and some mesograzers consumed macrophytes or exhibited intra-guild predation in addition to feeding on periphyton and detritus. These findings corroborate conclusions from lab and mesocosm studies that the ecological impacts of mesograzers vary widely among species, and they emphasize the need for taxonomic resolution and ecological information within seagrass epifaunal communities. © 2011 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Seasonal and interannual change in a Chesapeake Bay eelgrass community: Insights into biotic and abiotic control of community structure.\n \n \n \n\n\n \n Douglass, J. G.; France, K. E.; Richardson, J. P.; and Duffy, J. E.\n\n\n \n\n\n\n Limnology and Oceanography. 2010.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{douglass_seasonal_2010,\n\ttitle = {Seasonal and interannual change in a {Chesapeake} {Bay} eelgrass community: {Insights} into biotic and abiotic control of community structure},\n\tdoi = {10.4319/lo.2010.55.4.1499},\n\tabstract = {We characterized the seasonal and interannual variation in macrophytes, epiphytes, invertebrate herbivores, small demersal predators, and physicochemical characteristics of an eelgrass (Zostera marina) bed in Chesapeake Bay, Virginia, over 10 yr, to explore the relative importance of abiotic and biotic forcing on community composition and abundance. Our hypotheses were (1) physicochemical drivers affect community structure directly, (2) bottom-up trophic control is evidenced by positive covariance among trophic levels, (3) top-down control generates inverse patterns of abundance at adjacent trophic levels, and (4) species diversity among herbivores contributes to temporal stability. Composition and abundance of eelgrass-associated species varied strongly among seasons and years. Much of this variation correlated with temperature and salinity anomalies, and multivariate analysis grouped communities roughly by season, supporting our first hypothesis. Severe seagrass loss during the hot summer of 2005 shifted the community toward a novel composition, but community structure rebounded within a year. Evidence for trophic control was mixed: selected taxa showed patterns consistent with top-down or bottom-up control, but these patterns generally disappeared at the level of whole years and entire trophic levels. Our ability to detect trophic effects may have been limited, however, by consumer movement or changing behavioral responses to resource availability and predation. There was also little evidence that diversity stabilized total herbivore abundance. Although consumer effects on lower levels were inconsistent, the strong physicochemical forcing of community structure supports suggestions that eelgrass communities are highly vulnerable to natural and anthropogenic changes in climate and hydrography. © 2010, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Douglass, James G. and France, Kristin E. and Richardson, J. Paul and Duffy, J. Emmett},\n\tyear = {2010},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n We characterized the seasonal and interannual variation in macrophytes, epiphytes, invertebrate herbivores, small demersal predators, and physicochemical characteristics of an eelgrass (Zostera marina) bed in Chesapeake Bay, Virginia, over 10 yr, to explore the relative importance of abiotic and biotic forcing on community composition and abundance. Our hypotheses were (1) physicochemical drivers affect community structure directly, (2) bottom-up trophic control is evidenced by positive covariance among trophic levels, (3) top-down control generates inverse patterns of abundance at adjacent trophic levels, and (4) species diversity among herbivores contributes to temporal stability. Composition and abundance of eelgrass-associated species varied strongly among seasons and years. Much of this variation correlated with temperature and salinity anomalies, and multivariate analysis grouped communities roughly by season, supporting our first hypothesis. Severe seagrass loss during the hot summer of 2005 shifted the community toward a novel composition, but community structure rebounded within a year. Evidence for trophic control was mixed: selected taxa showed patterns consistent with top-down or bottom-up control, but these patterns generally disappeared at the level of whole years and entire trophic levels. Our ability to detect trophic effects may have been limited, however, by consumer movement or changing behavioral responses to resource availability and predation. There was also little evidence that diversity stabilized total herbivore abundance. Although consumer effects on lower levels were inconsistent, the strong physicochemical forcing of community structure supports suggestions that eelgrass communities are highly vulnerable to natural and anthropogenic changes in climate and hydrography. © 2010, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Using a fisheries ecosystem model with a water quality model to explore trophic and habitat impacts on a fisheries stock: A case study of the blue crab population in the Chesapeake Bay.\n \n \n \n\n\n \n Ma, H.; Townsend, H.; Zhang, X.; Sigrist, M.; and Christensen, V.\n\n\n \n\n\n\n Ecological Modelling. 2010.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ma_using_2010,\n\ttitle = {Using a fisheries ecosystem model with a water quality model to explore trophic and habitat impacts on a fisheries stock: {A} case study of the blue crab population in the {Chesapeake} {Bay}},\n\tdoi = {10.1016/j.ecolmodel.2009.01.026},\n\tabstract = {Recent calls for the development of ecosystem-based fisheries management compel the development of resource management tools and linkages between existing fisheries management tools and other resource tools to enable assessment and management of multiple impacts on fisheries resources. In this paper, we describe the use of the Chesapeake Bay Fisheries Ecosystem Model (CBFEM), developed using the Ecopath with Ecosim (EwE) software, and the Chesapeake Bay Water Quality Model (WQM) to demonstrate how linkages between available modeling tools can be used to inform ecosystem-based natural resource management. The CBFEM was developed to provide strategic ecosystem information in support of fisheries management. The WQM was developed to assess impacts on water quality. The CBFEM was indirectly coupled with the WQM to assess the effects of water quality and submerged aquatic vegetation (SAV) on blue crabs. The output from two WQM scenarios (1985-1994), a baseline scenario representing actual nutrient inputs and another with reduced inputs based on a tributary management strategy, was incorporated into the CBFEM. The results suggested that blue crab biomass could be enhanced under management strategies (reduced nutrient input) when the effective search rate of blue crab young-of-the-year's (YOY's) predators or the vulnerability of blue crab YOY to its predators was adjusted by SAV. Such model linkages are important for incorporating physical and biological components of ecosystems in order to explore ecosystem-based fisheries management options.},\n\tjournal = {Ecological Modelling},\n\tauthor = {Ma, Hongguang and Townsend, Howard and Zhang, Xinsheng and Sigrist, Maddy and Christensen, Villy},\n\tyear = {2010},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Recent calls for the development of ecosystem-based fisheries management compel the development of resource management tools and linkages between existing fisheries management tools and other resource tools to enable assessment and management of multiple impacts on fisheries resources. In this paper, we describe the use of the Chesapeake Bay Fisheries Ecosystem Model (CBFEM), developed using the Ecopath with Ecosim (EwE) software, and the Chesapeake Bay Water Quality Model (WQM) to demonstrate how linkages between available modeling tools can be used to inform ecosystem-based natural resource management. The CBFEM was developed to provide strategic ecosystem information in support of fisheries management. The WQM was developed to assess impacts on water quality. The CBFEM was indirectly coupled with the WQM to assess the effects of water quality and submerged aquatic vegetation (SAV) on blue crabs. The output from two WQM scenarios (1985-1994), a baseline scenario representing actual nutrient inputs and another with reduced inputs based on a tributary management strategy, was incorporated into the CBFEM. The results suggested that blue crab biomass could be enhanced under management strategies (reduced nutrient input) when the effective search rate of blue crab young-of-the-year's (YOY's) predators or the vulnerability of blue crab YOY to its predators was adjusted by SAV. Such model linkages are important for incorporating physical and biological components of ecosystems in order to explore ecosystem-based fisheries management options.\n
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\n \n\n \n \n \n \n \n Epifaunal community composition and nutrient addition alter sediment organic matter composition in a natural eelgrass Zostera marina bed: A field experiment.\n \n \n \n\n\n \n Spivak, A. C.; Canuel, E. A.; Duffy, J. E.; Douglass, J. G.; and Richardson, J. P.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{spivak_epifaunal_2009,\n\ttitle = {Epifaunal community composition and nutrient addition alter sediment organic matter composition in a natural eelgrass {Zostera} marina bed: {A} field experiment},\n\tdoi = {10.3354/meps07813},\n\tabstract = {Eutrophication and fishing are common perturbations in aquatic ecosystems that have pervasive effects on community structure, including species diversity and abundance. While sediment biogeochemical processes probably respond to these stressors, the linkages to ecosystem functioning remain poorly understood. To explore these linkages, we experimentally manipulated water column nutrient levels and food web composition (i.e. predator and grazer presence and absence) in a factorial design using field enclosures situated in a natural eelgrass Zostera marina bed. After 28 d, we quantified sediment organic matter (SOM) abundance and composition using measures of total organic carbon and nitrogen as well as fatty acid (FA) biomarkers. Nutrient enrichment led to a rapid increase of epiphytes and a decline in Z. marina biomass. Responding to the available algae, grazers reduced epiphytes and the abundance of microalgal FAs in the sediment. Predators reduced Z. marina abundance and possibly its ability to trap particulate organic matter (OM), leading to lower sediment organic carbon content and total FA abundance. There was evidence of a trophic cascade as FA contributions to sediments from epiphytes and diatoms were higher in treatments with both grazers and predators than in treatments with grazers only. Predators increased contributions of labile diatom-derived OM, which probably resulted in higher proportions of bacterial FA. Interactions between nutrient additions and food web composition indicated that SOM responses were complex and not predictable from single variables. Changes in SOM composition, combined with a rapid heterotrophic bacterial response, suggest that resource levels and aboveground community structure are important to sediment biogeochemistry in natural seagrass systems. © Inter-Research 2009.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Spivak, Amanda C. and Canuel, Elizabeth A. and Duffy, J. Emmett and Douglass, James G. and Richardson, J. Paul},\n\tyear = {2009},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Eutrophication and fishing are common perturbations in aquatic ecosystems that have pervasive effects on community structure, including species diversity and abundance. While sediment biogeochemical processes probably respond to these stressors, the linkages to ecosystem functioning remain poorly understood. To explore these linkages, we experimentally manipulated water column nutrient levels and food web composition (i.e. predator and grazer presence and absence) in a factorial design using field enclosures situated in a natural eelgrass Zostera marina bed. After 28 d, we quantified sediment organic matter (SOM) abundance and composition using measures of total organic carbon and nitrogen as well as fatty acid (FA) biomarkers. Nutrient enrichment led to a rapid increase of epiphytes and a decline in Z. marina biomass. Responding to the available algae, grazers reduced epiphytes and the abundance of microalgal FAs in the sediment. Predators reduced Z. marina abundance and possibly its ability to trap particulate organic matter (OM), leading to lower sediment organic carbon content and total FA abundance. There was evidence of a trophic cascade as FA contributions to sediments from epiphytes and diatoms were higher in treatments with both grazers and predators than in treatments with grazers only. Predators increased contributions of labile diatom-derived OM, which probably resulted in higher proportions of bacterial FA. Interactions between nutrient additions and food web composition indicated that SOM responses were complex and not predictable from single variables. Changes in SOM composition, combined with a rapid heterotrophic bacterial response, suggest that resource levels and aboveground community structure are important to sediment biogeochemistry in natural seagrass systems. © Inter-Research 2009.\n
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\n \n\n \n \n \n \n \n Spatial and temporal variability of juvenile spotted seatrout Cynoscion nebulosus growth in Chesapeake Bay.\n \n \n \n\n\n \n Smith, N. G.; Jones, C. M.; and Van Montfrans, J.\n\n\n \n\n\n\n Journal of Fish Biology. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{smith_spatial_2008,\n\ttitle = {Spatial and temporal variability of juvenile spotted seatrout {Cynoscion} nebulosus growth in {Chesapeake} {Bay}},\n\tdoi = {10.1111/j.1095-8649.2008.01954.x},\n\tabstract = {Juvenile spotted seatrout Cynoscion nebulosus growth in Chesapeake Bay was compared to growth from southerly estuaries to examine the potential for countergradient growth variation, and finer scale growth variation within Chesapeake Bay was investigated further. Because spawning and growing seasons in Chesapeake Bay are much shorter than in southern populations, and the bay population is genetically distinct, it was expected that C. nebulosus in Chesapeake Bay may exhibit faster juvenile growth than their southern counterparts. Within the bay, spatial and temporal growth patterns were examined using a repeated measures linear mixed-effects model on individual retrospective growth histories. Juvenile C. nebulosus were collected from seagrass beds throughout Chesapeake Bay in 1997-1999 and 2002; sagittae were removed for daily growth analysis. The calculated growth rate of 1.44 mm standard length day-1 for Chesapeake Bay fish is two to three times that reported for Florida C. nebulosus. Within the bay from 1997 to 1999 (average rainfall years), growth patterns were similar with the fastest growing fish collected from seagrass beds in the central bay, followed by the eastern shore fish with intermediate growth and western shore fish that exhibited slowest growth. These results were reversed (western shore fish growth {\\textbackslash}textgreater eastern shore {\\textbackslash}textgreater central bay) in 2002 (a drought year) even though temperatures across all years were similar throughout the bay, indicating that growth may be influenced by freshwater inflows. © 2008 The Authors.},\n\tjournal = {Journal of Fish Biology},\n\tauthor = {Smith, N. G. and Jones, C. M. and Van Montfrans, J.},\n\tyear = {2008},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Juvenile spotted seatrout Cynoscion nebulosus growth in Chesapeake Bay was compared to growth from southerly estuaries to examine the potential for countergradient growth variation, and finer scale growth variation within Chesapeake Bay was investigated further. Because spawning and growing seasons in Chesapeake Bay are much shorter than in southern populations, and the bay population is genetically distinct, it was expected that C. nebulosus in Chesapeake Bay may exhibit faster juvenile growth than their southern counterparts. Within the bay, spatial and temporal growth patterns were examined using a repeated measures linear mixed-effects model on individual retrospective growth histories. Juvenile C. nebulosus were collected from seagrass beds throughout Chesapeake Bay in 1997-1999 and 2002; sagittae were removed for daily growth analysis. The calculated growth rate of 1.44 mm standard length day-1 for Chesapeake Bay fish is two to three times that reported for Florida C. nebulosus. Within the bay from 1997 to 1999 (average rainfall years), growth patterns were similar with the fastest growing fish collected from seagrass beds in the central bay, followed by the eastern shore fish with intermediate growth and western shore fish that exhibited slowest growth. These results were reversed (western shore fish growth \\textgreater eastern shore \\textgreater central bay) in 2002 (a drought year) even though temperatures across all years were similar throughout the bay, indicating that growth may be influenced by freshwater inflows. © 2008 The Authors.\n
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\n \n\n \n \n \n \n \n Trophic transfers from seagrass meadows subsidize diverse marine and terrestrial consumers.\n \n \n \n\n\n \n Heck, K. L.; Carruthers, T. J.; Duarte, C. M.; Randall Hughes, A.; Kendrick, G.; Orth, R. J.; and Williams, S. W.\n\n\n \n\n\n\n 2008.\n Publication Title: Ecosystems\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@book{heck_trophic_2008,\n\ttitle = {Trophic transfers from seagrass meadows subsidize diverse marine and terrestrial consumers},\n\tabstract = {In many coastal locations, seagrass meadows are part of a greater seascape that includes both marine and terrestrial elements, each linked to the other via the foraging patterns of consumers (both predators and herbivores), and the passive drift of seagrass propagules, leaves, roots and rhizomes, and seagrass-associated macroalgal detritus. With seagrasses declining in many regions, the linkages between seagrass meadows and other habitats are being altered and diminished. Thus, it is timely to summarize what is known about the prevalence and magnitude of cross-habitat exchanges of seagrass- derived energy and materials, and to increase awareness of the importance of seagrasses to adjacent and even distant habitats. To do so we examined the literature on the extent and importance of exchanges of biomass between seagrass meadows and other habitats, both in the form of exported seagrass biomass as well as transfers of animal biomass via migration. Data were most abundant for Caribbean coral reefs and Australian beaches, and organisms for which there were quantitative estimates included Caribbean fishes and North American migratory waterfowl. Overall, data from the studies we reviewed clearly showed that seagrass ecosystems provide a large subsidy to both near and distant locations through the export of particulate organic matter and living plant and animal biomass. The consequences of continuing seagrass decline thus extend far beyond the areas where seagrasses grow.},\n\tauthor = {Heck, Kenneth L. and Carruthers, Tim J.B. and Duarte, Carlos M. and Randall Hughes, A. and Kendrick, Gary and Orth, Robert J. and Williams, Susan W.},\n\tyear = {2008},\n\tdoi = {10.1007/s10021-008-9155-y},\n\tnote = {Publication Title: Ecosystems},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n In many coastal locations, seagrass meadows are part of a greater seascape that includes both marine and terrestrial elements, each linked to the other via the foraging patterns of consumers (both predators and herbivores), and the passive drift of seagrass propagules, leaves, roots and rhizomes, and seagrass-associated macroalgal detritus. With seagrasses declining in many regions, the linkages between seagrass meadows and other habitats are being altered and diminished. Thus, it is timely to summarize what is known about the prevalence and magnitude of cross-habitat exchanges of seagrass- derived energy and materials, and to increase awareness of the importance of seagrasses to adjacent and even distant habitats. To do so we examined the literature on the extent and importance of exchanges of biomass between seagrass meadows and other habitats, both in the form of exported seagrass biomass as well as transfers of animal biomass via migration. Data were most abundant for Caribbean coral reefs and Australian beaches, and organisms for which there were quantitative estimates included Caribbean fishes and North American migratory waterfowl. Overall, data from the studies we reviewed clearly showed that seagrass ecosystems provide a large subsidy to both near and distant locations through the export of particulate organic matter and living plant and animal biomass. The consequences of continuing seagrass decline thus extend far beyond the areas where seagrasses grow.\n
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\n \n\n \n \n \n \n \n Herbivore and predator diversity interactively affect ecosystem properties in an experimental marine community.\n \n \n \n\n\n \n Douglass, J. G.; Duffy, J. E.; and Bruno, J. F.\n\n\n \n\n\n\n Ecology Letters. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{douglass_herbivore_2008,\n\ttitle = {Herbivore and predator diversity interactively affect ecosystem properties in an experimental marine community},\n\tdoi = {10.1111/j.1461-0248.2008.01175.x},\n\tabstract = {Interacting changes in predator and prey diversity likely influence ecosystem properties but have rarely been experimentally tested. We manipulated the species richness of herbivores and predators in an experimental benthic marine community and measured their effects on predator, herbivore and primary producer performance. Predator composition and richness strongly affected several community and population responses, mostly via sampling effects. However, some predators survived better in polycultures than in monocultures, suggesting complementarity due to stronger intra- than interspecific interactions. Predator effects also differed between additive and substitutive designs, emphasizing that the relationship between diversity and abundance in an assemblage can strongly influence whether and how diversity effects are realized. Changing herbivore richness and predator richness interacted to influence both total herbivore abundance and predatory crab growth, but these interactive diversity effects were weak. Overall, the presence and richness of predators dominated biotic effects on community and ecosystem properties. © 2008 Blackwell Publishing Ltd/CNRS.},\n\tjournal = {Ecology Letters},\n\tauthor = {Douglass, James G. and Duffy, J. Emmett and Bruno, John F.},\n\tyear = {2008},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n Interacting changes in predator and prey diversity likely influence ecosystem properties but have rarely been experimentally tested. We manipulated the species richness of herbivores and predators in an experimental benthic marine community and measured their effects on predator, herbivore and primary producer performance. Predator composition and richness strongly affected several community and population responses, mostly via sampling effects. However, some predators survived better in polycultures than in monocultures, suggesting complementarity due to stronger intra- than interspecific interactions. Predator effects also differed between additive and substitutive designs, emphasizing that the relationship between diversity and abundance in an assemblage can strongly influence whether and how diversity effects are realized. Changing herbivore richness and predator richness interacted to influence both total herbivore abundance and predatory crab growth, but these interactive diversity effects were weak. Overall, the presence and richness of predators dominated biotic effects on community and ecosystem properties. © 2008 Blackwell Publishing Ltd/CNRS.\n
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\n \n\n \n \n \n \n \n Relating otolith chemistry to surface water chemistry in a coastal plain estuary.\n \n \n \n\n\n \n Dorval, E.; Jones, C. M.; Hannigan, R.; and Van Montfrans, J.\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{dorval_relating_2007,\n\ttitle = {Relating otolith chemistry to surface water chemistry in a coastal plain estuary},\n\tdoi = {10.1139/F07-015},\n\tabstract = {Although laboratory studies confirm that otoliths incorporate trace elements and stable isotopes from surrounding waters, few studies explore the relationship of otolith chemistry to water chemistry in the field and none include a larger suite of environmental tracers, such as rare earth elements. Using spotted seatrout (Cynoscion nebulosus) as model species, we tested the hypothesis that otoliths record the water chemistry of seagrass habitats in Chesapeake Bay. In summer 2001, we sampled water and juvenile fish in seagrass beds of the bay. Weighted linear regressions showed that [Ba/Ca] otolith and [La/Ca]otolith were best predicted by salinity and were modeled as [Ba/Ca]otolith (μmol·mol-1) = -2.25 ± 0.35 x salinity + 59.47 ± 7.01) and [La/Ca] otolith (pmol·mol-1) = -8.71 ± 0.65 x salinity + 243.87 ± 12.52. [Ba/Ca]otolith increased with [Ba/Ca]water, but the relationship was nonlinear. Salinity did not influence [Mn/Ca]otolith, but this ratio was positively correlated with [Mn/Ca]water. Although the partition coefficient of Sr (D Sr = 0.23 ± 0.019) was similar to that in laboratory experiments, [Sr/Ca] in waters and otoliths was decoupled despite equal temperature exposure, suggesting that [Sr/Ca]otolith concentration may not be a simple function of water composition. However, there was a predictive relationship between [δ18O]otolith and [Sr/Ca]water ([δ18O]otolith = 1.18 ± 0.09 x [Sr/Ca]water (mmol·mol-1) - 14.286 ± 0.78) resulting from mixing between fluvial and oceanic waters. Water chemistry showed mixed values as a proxy for otolith chemistry and may not be a surrogate for otolith chemistry in wide estuaries. © 2007 NRC.},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Dorval, Emmanis and Jones, Cynthia M. and Hannigan, Robyn and Van Montfrans, Jacques},\n\tyear = {2007},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Although laboratory studies confirm that otoliths incorporate trace elements and stable isotopes from surrounding waters, few studies explore the relationship of otolith chemistry to water chemistry in the field and none include a larger suite of environmental tracers, such as rare earth elements. Using spotted seatrout (Cynoscion nebulosus) as model species, we tested the hypothesis that otoliths record the water chemistry of seagrass habitats in Chesapeake Bay. In summer 2001, we sampled water and juvenile fish in seagrass beds of the bay. Weighted linear regressions showed that [Ba/Ca] otolith and [La/Ca]otolith were best predicted by salinity and were modeled as [Ba/Ca]otolith (μmol·mol-1) = -2.25 ± 0.35 x salinity + 59.47 ± 7.01) and [La/Ca] otolith (pmol·mol-1) = -8.71 ± 0.65 x salinity + 243.87 ± 12.52. [Ba/Ca]otolith increased with [Ba/Ca]water, but the relationship was nonlinear. Salinity did not influence [Mn/Ca]otolith, but this ratio was positively correlated with [Mn/Ca]water. Although the partition coefficient of Sr (D Sr = 0.23 ± 0.019) was similar to that in laboratory experiments, [Sr/Ca] in waters and otoliths was decoupled despite equal temperature exposure, suggesting that [Sr/Ca]otolith concentration may not be a simple function of water composition. However, there was a predictive relationship between [δ18O]otolith and [Sr/Ca]water ([δ18O]otolith = 1.18 ± 0.09 x [Sr/Ca]water (mmol·mol-1) - 14.286 ± 0.78) resulting from mixing between fluvial and oceanic waters. Water chemistry showed mixed values as a proxy for otolith chemistry and may not be a surrogate for otolith chemistry in wide estuaries. © 2007 NRC.\n
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\n \n\n \n \n \n \n \n The functional role of biodiversity in ecosystems: Incorporating trophic complexity.\n \n \n \n\n\n \n Duffy, J. E.; Cardinale, B. J.; France, K. E.; McIntyre, P. B.; Thébault, E.; and Loreau, M.\n\n\n \n\n\n\n 2007.\n Publication Title: Ecology Letters\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@book{duffy_functional_2007,\n\ttitle = {The functional role of biodiversity in ecosystems: {Incorporating} trophic complexity},\n\tabstract = {Understanding how biodiversity affects functioning of ecosystems requires integrating diversity within trophic levels (horizontal diversity) and across trophic levels (vertical diversity, including food chain length and omnivory). We review theoretical and experimental progress toward this goal. Generally, experiments show that biomass and resource use increase similarly with horizontal diversity of either producers or consumers. Among prey, higher diversity often increases resistance to predation, due to increased probability of including inedible species and reduced efficiency of specialist predators confronted with diverse prey. Among predators, changing diversity can cascade to affect plant biomass, but the strength and sign of this effect depend on the degree of omnivory and prey behaviour. Horizontal and vertical diversity also interact: adding a trophic level can qualitatively change diversity effects at adjacent levels. Multitrophic interactions produce a richer variety of diversity-functioning relationships than the monotonic changes predicted for single trophic levels. This complexity depends on the degree of consumer dietary generalism, trade-offs between competitive ability and resistance to predation, intraguild predation and openness to migration. Although complementarity and selection effects occur in both animals and plants, few studies have conclusively documented the mechanisms mediating diversity effects. Understanding how biodiversity affects functioning of complex ecosystems will benefit from integrating theory and experiments with simulations and network-based approaches. © 2007 Blackwell Publishing Ltd/CNRS.},\n\tauthor = {Duffy, J. Emmett and Cardinale, Bradley J. and France, Kristin E. and McIntyre, Peter B. and Thébault, Elisa and Loreau, Michel},\n\tyear = {2007},\n\tdoi = {10.1111/j.1461-0248.2007.01037.x},\n\tnote = {Publication Title: Ecology Letters},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Understanding how biodiversity affects functioning of ecosystems requires integrating diversity within trophic levels (horizontal diversity) and across trophic levels (vertical diversity, including food chain length and omnivory). We review theoretical and experimental progress toward this goal. Generally, experiments show that biomass and resource use increase similarly with horizontal diversity of either producers or consumers. Among prey, higher diversity often increases resistance to predation, due to increased probability of including inedible species and reduced efficiency of specialist predators confronted with diverse prey. Among predators, changing diversity can cascade to affect plant biomass, but the strength and sign of this effect depend on the degree of omnivory and prey behaviour. Horizontal and vertical diversity also interact: adding a trophic level can qualitatively change diversity effects at adjacent levels. Multitrophic interactions produce a richer variety of diversity-functioning relationships than the monotonic changes predicted for single trophic levels. This complexity depends on the degree of consumer dietary generalism, trade-offs between competitive ability and resistance to predation, intraguild predation and openness to migration. Although complementarity and selection effects occur in both animals and plants, few studies have conclusively documented the mechanisms mediating diversity effects. Understanding how biodiversity affects functioning of complex ecosystems will benefit from integrating theory and experiments with simulations and network-based approaches. © 2007 Blackwell Publishing Ltd/CNRS.\n
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\n \n\n \n \n \n \n \n Long-term changes in abundance and diversity of macrophyte and waterfowl populations in an estuary with exotic macrophytes and improving water quality.\n \n \n \n\n\n \n Rybicki, N. B.; and Landwehr, J. M.\n\n\n \n\n\n\n Limnology and Oceanography. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{rybicki_long-term_2007,\n\ttitle = {Long-term changes in abundance and diversity of macrophyte and waterfowl populations in an estuary with exotic macrophytes and improving water quality},\n\tdoi = {10.4319/lo.2007.52.3.1195},\n\tabstract = {We assessed species-specific coverage (km2) of a submerged aquatic vegetation (SAV) community in the fresh and upper oligohaline Potomac Estuary from 1985 to 2001 using a method combining field observations of species-proportional coverage data with congruent remotely sensed coverage and density (percent canopy cover) data. Biomass (estimated by density-weighted coverage) of individual species was calculated. Under improving water quality conditions, exotic SAV species did not displace native SAV; rather, the percent of natives increased over time. While coverage-based diversity did fluctuate and increased, richness-based community turnover rates were not significantly different from zero. SAV diversity was negatively related to nitrogen concentration. Differences in functional traits, such as reproductive potential, between the dominant native and exotic species may explain some interannual patterns in SAV. Biomass of native, as well as exotic, SAV species varied with factors affecting water column light attenuation. We also show a positive response by a higher trophic level, waterfowl, to SAV communities dominated by exotic SAV from 1959 to 2001. © 2007, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Rybicki, Nancy B. and Landwehr, Jurate M.},\n\tyear = {2007},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n We assessed species-specific coverage (km2) of a submerged aquatic vegetation (SAV) community in the fresh and upper oligohaline Potomac Estuary from 1985 to 2001 using a method combining field observations of species-proportional coverage data with congruent remotely sensed coverage and density (percent canopy cover) data. Biomass (estimated by density-weighted coverage) of individual species was calculated. Under improving water quality conditions, exotic SAV species did not displace native SAV; rather, the percent of natives increased over time. While coverage-based diversity did fluctuate and increased, richness-based community turnover rates were not significantly different from zero. SAV diversity was negatively related to nitrogen concentration. Differences in functional traits, such as reproductive potential, between the dominant native and exotic species may explain some interannual patterns in SAV. Biomass of native, as well as exotic, SAV species varied with factors affecting water column light attenuation. We also show a positive response by a higher trophic level, waterfowl, to SAV communities dominated by exotic SAV from 1959 to 2001. © 2007, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Nutrient versus consumer control of community structure in a Chesapeake Bay eelgrass habitat.\n \n \n \n\n\n \n Douglass, J. G.; Duffy, J. E.; Spivak, A. C.; and Richardson, J. P.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{douglass_nutrient_2007,\n\ttitle = {Nutrient versus consumer control of community structure in a {Chesapeake} {Bay} eelgrass habitat},\n\tdoi = {10.3354/meps07091},\n\tabstract = {Nutrient loading can dramatically alter benthic communities and has been implicated in the worldwide decline of seagrass beds. Ongoing changes in food webs caused by overfishing could also contribute to seagrass decline. However, the interaction of these factors and the role of small invertebrate grazers in mediating them are poorly understood. We examined the relative impacts of nutrient loading and food web alteration on eelgrass Zostera marina L. community structure in Chesapeake Bay by manipulating nutrients, predatory crabs, and invertebrate grazers in field enclosures over 28 d in summer. Nutrient loading increased epiphyte accumulation early in the experiment, decreased eelgrass biomass, and reduced the abundance of the colonial tunicate Botryllus schlosseri. Grazers decreased epiphyte accumulation, altered the recruitment of sessile invertebrates, and sometimes damaged eelgrass via overgrazing. Crabs reduced the abundance of eelgrass, and changed the species composition and abundance of grazers and sessile invertebrates. On average, the impacts of food web alterations and nutrient loading were comparable in magnitude and tended to be additive, rather than interactive. However, the distinct responses of different taxa in the community to the experimental treatments indicated that food web structure interacted with both bottom-up and top-down forces to determine overall community organization. These results highlight the importance of incorporating food web dynamics into seagrass conservation and management efforts. © Inter-Research 2007.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Douglass, James Grayland and Duffy, J. Emmett and Spivak, Amanda C. and Richardson, John Paul},\n\tyear = {2007},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Nutrient loading can dramatically alter benthic communities and has been implicated in the worldwide decline of seagrass beds. Ongoing changes in food webs caused by overfishing could also contribute to seagrass decline. However, the interaction of these factors and the role of small invertebrate grazers in mediating them are poorly understood. We examined the relative impacts of nutrient loading and food web alteration on eelgrass Zostera marina L. community structure in Chesapeake Bay by manipulating nutrients, predatory crabs, and invertebrate grazers in field enclosures over 28 d in summer. Nutrient loading increased epiphyte accumulation early in the experiment, decreased eelgrass biomass, and reduced the abundance of the colonial tunicate Botryllus schlosseri. Grazers decreased epiphyte accumulation, altered the recruitment of sessile invertebrates, and sometimes damaged eelgrass via overgrazing. Crabs reduced the abundance of eelgrass, and changed the species composition and abundance of grazers and sessile invertebrates. On average, the impacts of food web alterations and nutrient loading were comparable in magnitude and tended to be additive, rather than interactive. However, the distinct responses of different taxa in the community to the experimental treatments indicated that food web structure interacted with both bottom-up and top-down forces to determine overall community organization. These results highlight the importance of incorporating food web dynamics into seagrass conservation and management efforts. © Inter-Research 2007.\n
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\n \n\n \n \n \n \n \n Restoration of waterbird habitats in Chesapeake Bay: great expectations or Sisyphus revisited?.\n \n \n \n\n\n \n Michael, R E.; and A., R. B.\n\n\n \n\n\n\n Waterbirds. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{michael_restoration_2007,\n\ttitle = {Restoration of waterbird habitats in {Chesapeake} {Bay}: great expectations or {Sisyphus} revisited?},\n\tabstract = {In the past half century, many waterbird populations in Chesapeake Bay have declined or shiftedranges, indicating major ecological changes have occurred. While many studies have focused on the problems associatedwith environmental degradation such as the losses of coastal wetlands and submerged vegetation, a numberof restoration efforts have been launched in the past few decades to reverse the “sea of despair.” Most pertinentto waterbirds, restoration of submerged aquatic vegetation (SAV) beds, tidal wetland restoration, oyster reef restoration,and island creation/restoration have benefited a number of species. State and federal agencies and nongovernmentagencies have formed partnerships to spawn many projects ranging in size from less than 0.5 ha to ca.1,000 ha. While most SAV, wetland, and oyster reef projects have struggled to different degrees over the past ten totwenty years with inconsistent methods, irregular monitoring, and unknown reasons for failures, recent improvementsin techniques and application of adaptive management have been made. The large dredge-material islandprojects at Hart-Miller Island near Baltimore, Poplar Island west of Tilghman Island, Maryland, and Craney Islandin Portsmouth, Virginia have provided large outdoor “laboratories” for wildlife, fishery, and wetland habitat creation.All three have proven to be important for nesting waterbirds and migrant shorebirds and waterfowl; howevernesting populations at all three islands have been compromised to different degrees by predators. Restoration successfor waterbirds and other natural resources depends on: (1) establishing realistic, quantifiable objectives andperformance criteria, (2) continued monitoring and management (e.g., predator control), (3) targeted researchto determine causality, and (4) careful evaluation under an adaptive management regime.},\n\tjournal = {Waterbirds},\n\tauthor = {Michael, R Erwin and A., Ruth Beck},\n\tyear = {2007},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n In the past half century, many waterbird populations in Chesapeake Bay have declined or shiftedranges, indicating major ecological changes have occurred. While many studies have focused on the problems associatedwith environmental degradation such as the losses of coastal wetlands and submerged vegetation, a numberof restoration efforts have been launched in the past few decades to reverse the “sea of despair.” Most pertinentto waterbirds, restoration of submerged aquatic vegetation (SAV) beds, tidal wetland restoration, oyster reef restoration,and island creation/restoration have benefited a number of species. State and federal agencies and nongovernmentagencies have formed partnerships to spawn many projects ranging in size from less than 0.5 ha to ca.1,000 ha. While most SAV, wetland, and oyster reef projects have struggled to different degrees over the past ten totwenty years with inconsistent methods, irregular monitoring, and unknown reasons for failures, recent improvementsin techniques and application of adaptive management have been made. The large dredge-material islandprojects at Hart-Miller Island near Baltimore, Poplar Island west of Tilghman Island, Maryland, and Craney Islandin Portsmouth, Virginia have provided large outdoor “laboratories” for wildlife, fishery, and wetland habitat creation.All three have proven to be important for nesting waterbirds and migrant shorebirds and waterfowl; howevernesting populations at all three islands have been compromised to different degrees by predators. Restoration successfor waterbirds and other natural resources depends on: (1) establishing realistic, quantifiable objectives andperformance criteria, (2) continued monitoring and management (e.g., predator control), (3) targeted researchto determine causality, and (4) careful evaluation under an adaptive management regime.\n
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\n \n\n \n \n \n \n \n Biodiversity and food web structure influence short-term accumulation of sediment organic matter in an experimental seagrass system.\n \n \n \n\n\n \n Canuel, E. A.; Spivak, A. C.; Waterson, E. J.; and Duffy, J. E.\n\n\n \n\n\n\n Limnology and Oceanography. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 1 download\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{canuel_biodiversity_2007,\n\ttitle = {Biodiversity and food web structure influence short-term accumulation of sediment organic matter in an experimental seagrass system},\n\tdoi = {10.4319/lo.2007.52.2.0590},\n\tabstract = {We tested the effects of grazer diversity and food chain length on the quantity and quality of accumulated sediment organic matter (SOM) in experimental eelgrass (Zostera marina) mesocosms. By use of a factorial manipulation of crustacean grazer species richness and predator presence, we examined the effects of epibenthic consumers on SOM composition by using stable carbon isotopes (δ13C) and lipid biomarker compounds. Grazer species composition strongly influenced nearly all measures of SOM quantity and quality. In particular, increased densities of the grazing amphipod, Gammarus mucronatus, decreased accumulation of benthic microalgae (chlorophyll a) and the relative abundance of polyunsaturated fatty acids (FA, a proxy for labile algal organic matter) and branched FA (a proxy for bacterial biomass). On average, increasing grazer species richness decreased SOM quantity (percentage of total organic carbon). Increasing food chain length by addition of predatory blue crabs (Callinectes sapidus) resulted in a trophic cascade, increasing algal biomass and accumulation of algal organic matter in sediments, and enhancing the quality of SOM. Concomitantly, the relative proportion of bacterial branched FA increased. The identity and number of epibenthic consumers strongly influence accumulation and composition of SOM and the pathways by which it is processed, and these responses are not easily predictable from bulk measurements (δ13C, percentage of total organic carbon) alone. © 2007, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Canuel, Elizabeth A. and Spivak, Amanda C. and Waterson, Elizabeth J. and Duffy, J. Emmett},\n\tyear = {2007},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n We tested the effects of grazer diversity and food chain length on the quantity and quality of accumulated sediment organic matter (SOM) in experimental eelgrass (Zostera marina) mesocosms. By use of a factorial manipulation of crustacean grazer species richness and predator presence, we examined the effects of epibenthic consumers on SOM composition by using stable carbon isotopes (δ13C) and lipid biomarker compounds. Grazer species composition strongly influenced nearly all measures of SOM quantity and quality. In particular, increased densities of the grazing amphipod, Gammarus mucronatus, decreased accumulation of benthic microalgae (chlorophyll a) and the relative abundance of polyunsaturated fatty acids (FA, a proxy for labile algal organic matter) and branched FA (a proxy for bacterial biomass). On average, increasing grazer species richness decreased SOM quantity (percentage of total organic carbon). Increasing food chain length by addition of predatory blue crabs (Callinectes sapidus) resulted in a trophic cascade, increasing algal biomass and accumulation of algal organic matter in sediments, and enhancing the quality of SOM. Concomitantly, the relative proportion of bacterial branched FA increased. The identity and number of epibenthic consumers strongly influence accumulation and composition of SOM and the pathways by which it is processed, and these responses are not easily predictable from bulk measurements (δ13C, percentage of total organic carbon) alone. © 2007, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Impacts of biodiversity loss on ocean ecosystem services.\n \n \n \n\n\n \n Worm, B.; Barbier, E. B.; Beaumont, N.; Duffy, J. E.; Folke, C.; Halpern, B. S.; Jackson, J. B.; Lotze, H. K.; Micheli, F.; Palumbi, S. R.; Sala, E.; Selkoe, K. A.; Stachowicz, J. J.; and Watson, R.\n\n\n \n\n\n\n Science. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{worm_impacts_2006,\n\ttitle = {Impacts of biodiversity loss on ocean ecosystem services},\n\tdoi = {10.1126/science.1132294},\n\tabstract = {Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability by 21\\%, on average. We conclude that marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from perturbations. Yet available data suggest that at this point, these trends are still reversible.},\n\tjournal = {Science},\n\tauthor = {Worm, Boris and Barbier, Edward B. and Beaumont, Nicola and Duffy, J. Emmett and Folke, Carl and Halpern, Benjamin S. and Jackson, Jeremy B.C. and Lotze, Heike K. and Micheli, Fiorenza and Palumbi, Stephen R. and Sala, Enric and Selkoe, Kimberley A. and Stachowicz, John J. and Watson, Reg},\n\tyear = {2006},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n Human-dominated marine ecosystems are experiencing accelerating loss of populations and species, with largely unknown consequences. We analyzed local experiments, long-term regional time series, and global fisheries data to test how biodiversity loss affects marine ecosystem services across temporal and spatial scales. Overall, rates of resource collapse increased and recovery potential, stability, and water quality decreased exponentially with declining diversity. Restoration of biodiversity, in contrast, increased productivity fourfold and decreased variability by 21%, on average. We conclude that marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from perturbations. Yet available data suggest that at this point, these trends are still reversible.\n
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\n \n\n \n \n \n \n \n Consumer diversity mediates invasion dynamics at multiple trophic levels.\n \n \n \n\n\n \n France, K E; and Duffy, J E\n\n\n \n\n\n\n Oikos. 2006.\n ISBN: 0030-1299\n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{france_consumer_2006,\n\ttitle = {Consumer diversity mediates invasion dynamics at multiple trophic levels},\n\tabstract = {Theory and recent experiments, mostly focused on plants, indicate that biodiversity can reduce invasion success, but diversity effects on mobile animal invasion have received little attention. We tested effects of mobile crustacean grazer diversity (species richness) on the establishment of invaders at multiple trophic levels in flow-through seagrass mesocosms. On average, increasing diversity of resident grazers reduced population growth and biomass of experimentally introduced grazers. This increase in invasion resistance was concurrent with reductions in food and habitat availability and increases in resident density, paralleling previous results with plants. In many cases, mixtures of resident species resisted invasion better than did any single resident species, arguing that interactions among residents, rather than a sampling mechanism, explained diversity effects on invasion. Higher grazer diversity also generally reduced biomass of naturally recruiting invertebrates and algae and shifted epiphytic community dominance from algae to sessile invertebrates. Exploitation competition, then, appears to contribute to the diversity effect on invasion in both plant and animal systems. Our results further suggest that resident competitive advantage may also be at work in multi-trophic level systems. Thus, negative effects of local diversity on invasion appear general, and trophically mediated processes can also strongly influence invader success and identity in multi-trophic level systems.},\n\tjournal = {Oikos},\n\tauthor = {France, K E and Duffy, J E},\n\tyear = {2006},\n\tnote = {ISBN: 0030-1299},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Theory and recent experiments, mostly focused on plants, indicate that biodiversity can reduce invasion success, but diversity effects on mobile animal invasion have received little attention. We tested effects of mobile crustacean grazer diversity (species richness) on the establishment of invaders at multiple trophic levels in flow-through seagrass mesocosms. On average, increasing diversity of resident grazers reduced population growth and biomass of experimentally introduced grazers. This increase in invasion resistance was concurrent with reductions in food and habitat availability and increases in resident density, paralleling previous results with plants. In many cases, mixtures of resident species resisted invasion better than did any single resident species, arguing that interactions among residents, rather than a sampling mechanism, explained diversity effects on invasion. Higher grazer diversity also generally reduced biomass of naturally recruiting invertebrates and algae and shifted epiphytic community dominance from algae to sessile invertebrates. Exploitation competition, then, appears to contribute to the diversity effect on invasion in both plant and animal systems. Our results further suggest that resident competitive advantage may also be at work in multi-trophic level systems. Thus, negative effects of local diversity on invasion appear general, and trophically mediated processes can also strongly influence invader success and identity in multi-trophic level systems.\n
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\n \n\n \n \n \n \n \n Diversity and dispersal interactively affect predictability of ecosystem function.\n \n \n \n\n\n \n France, K. E.; and Duffy, J. E.\n\n\n \n\n\n\n Nature. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{france_diversity_2006,\n\ttitle = {Diversity and dispersal interactively affect predictability of ecosystem function},\n\tdoi = {10.1038/nature04729},\n\tabstract = {Theory and small-scale experiments predict that biodiversity losses can decrease the magnitude and stability of ecosystem services such as production and nutrient cycling. Most of this research, however, has been isolated from the immigration and emigration (dispersal) processes that create and maintain diversity in nature. As common anthropogenic drivers of biodiversity change-such as habitat fragmentation, species introductions and climate change-are mediated by these understudied processes, it is unclear how environmental degradation will affect ecosystem services. Here we tested the interactive effects of mobile grazer diversity and dispersal on the magnitude and stability of ecosystem properties in experimental seagrass communities that were either isolated or connected by dispersal corridors. We show that, contrary to theoretical predictions, increasing the number of mobile grazer species in these metacommunities increased the spatial and temporal variability of primary and secondary production. Moreover, allowing grazers to move among and select patches reduced diversity effects on production. Finally, effects of diversity on stability differed qualitatively between patch and metacommunity scales. Our results indicate that declining biodiversity and habitat fragmentation synergistically influence the predictability of ecosystem functioning. © 2006 Nature Publishing Group.},\n\tjournal = {Nature},\n\tauthor = {France, Kristin E. and Duffy, J. Emmett},\n\tyear = {2006},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Theory and small-scale experiments predict that biodiversity losses can decrease the magnitude and stability of ecosystem services such as production and nutrient cycling. Most of this research, however, has been isolated from the immigration and emigration (dispersal) processes that create and maintain diversity in nature. As common anthropogenic drivers of biodiversity change-such as habitat fragmentation, species introductions and climate change-are mediated by these understudied processes, it is unclear how environmental degradation will affect ecosystem services. Here we tested the interactive effects of mobile grazer diversity and dispersal on the magnitude and stability of ecosystem properties in experimental seagrass communities that were either isolated or connected by dispersal corridors. We show that, contrary to theoretical predictions, increasing the number of mobile grazer species in these metacommunities increased the spatial and temporal variability of primary and secondary production. Moreover, allowing grazers to move among and select patches reduced diversity effects on production. Finally, effects of diversity on stability differed qualitatively between patch and metacommunity scales. Our results indicate that declining biodiversity and habitat fragmentation synergistically influence the predictability of ecosystem functioning. © 2006 Nature Publishing Group.\n
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\n \n\n \n \n \n \n \n Why biodiversity is important to oceanography: Potential roles of genetic, species, and trophic diversity in pelagic ecosystem processes.\n \n \n \n\n\n \n Duffy, J. E.; and Stachowicz, J. J.\n\n\n \n\n\n\n 2006.\n Publication Title: Marine Ecology Progress Series\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@book{duffy_why_2006,\n\ttitle = {Why biodiversity is important to oceanography: {Potential} roles of genetic, species, and trophic diversity in pelagic ecosystem processes},\n\tabstract = {The functioning of the global ecosystem is mediated in large part by pelagic marine organisms through their influence on biomass production, elemental cycling, and atmospheric composition. Growing theoretical and empirical evidence suggests that the stability and functioning of this complex system may depend, not only on aggregate biomass and production of pelagic producers and consumers, but also on the composition and richness of taxa within those compartments. Yet rigorous experimental tests of relationships between diversity and these aspects of pelagic ecosystem functioning are virtually unknown. Here, we argue for more attention to such research, and we marshal preliminary evidence that several mechanisms underlying diversity effects on ecosystem processes in marine benthic and terrestrial systems also may operate in pelagic systems. We review selected examples of how genetic, species, and functional group diversity may affect ocean ecosystem processes. We consider 3 types of examples that detail how (1) producer richness or composition can directly affect ecosystem processes, (2) consumer diversity can directly and indirectly affect these same processes, and (3) diversity at and below the species level can reduce variation of communities through time and enhance their resistance to perturbations. We suggest several promising avenues for assessing the role of biodiversity in pelagic ecosystems. Understanding and predicting responses of the global ocean ecosystem to accelerating climate and environmental change will be enhanced by more explicit and systematic attention to the functional diversity of microbial and macroscopic marine life. © Inter-Research 2006.},\n\tauthor = {Duffy, J. Emmett and Stachowicz, John J.},\n\tyear = {2006},\n\tdoi = {10.3354/meps311179},\n\tnote = {Publication Title: Marine Ecology Progress Series},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n The functioning of the global ecosystem is mediated in large part by pelagic marine organisms through their influence on biomass production, elemental cycling, and atmospheric composition. Growing theoretical and empirical evidence suggests that the stability and functioning of this complex system may depend, not only on aggregate biomass and production of pelagic producers and consumers, but also on the composition and richness of taxa within those compartments. Yet rigorous experimental tests of relationships between diversity and these aspects of pelagic ecosystem functioning are virtually unknown. Here, we argue for more attention to such research, and we marshal preliminary evidence that several mechanisms underlying diversity effects on ecosystem processes in marine benthic and terrestrial systems also may operate in pelagic systems. We review selected examples of how genetic, species, and functional group diversity may affect ocean ecosystem processes. We consider 3 types of examples that detail how (1) producer richness or composition can directly affect ecosystem processes, (2) consumer diversity can directly and indirectly affect these same processes, and (3) diversity at and below the species level can reduce variation of communities through time and enhance their resistance to perturbations. We suggest several promising avenues for assessing the role of biodiversity in pelagic ecosystems. Understanding and predicting responses of the global ocean ecosystem to accelerating climate and environmental change will be enhanced by more explicit and systematic attention to the functional diversity of microbial and macroscopic marine life. © Inter-Research 2006.\n
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\n \n\n \n \n \n \n \n Biodiversity and the functioning of seagrass ecosystems.\n \n \n \n\n\n \n Duffy, J. E.\n\n\n \n\n\n\n 2006.\n Publication Title: Marine Ecology Progress Series\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@book{duffy_biodiversity_2006,\n\ttitle = {Biodiversity and the functioning of seagrass ecosystems},\n\tabstract = {Biodiversity at multiple levels - genotypes within species, species within functional groups, habitats within a landscape - enhances productivity, resource use, and stability of seagrass ecosystems. Several themes emerge from a review of the mostly indirect evidence and the few experiments that explicitly manipulated diversity in seagrass systems. First, because many seagrass communities are dominated by 1 or a few plant species, genetic and phenotypic diversity within such foundation species has important influences on ecosystem productivity and stability. Second, in seagrass beds and many other aquatic systems, consumer control is strong, extinction is biased toward large body size and high trophic levels, and thus human impacts are often mediated by interactions of changing 'vertical diversity' (food chain length) with changing 'horizontal diversity' (heterogeneity within trophic levels). Third, the openness of marine systems means that ecosystem structure and processes often depend on interactions among habitats within a landscape (landscape diversity). There is clear evidence from seagrass systems that advection of resources and active movement of consumers among adjacent habitats influence nutrient fluxes, trophic transfer, fishery production, and species diversity. Future investigations of biodiversity effects on processes within seagrass and other aquatic ecosystems would benefit from broadening the concept of biodiversity to encompass the hierarchy of genetic through landscape diversity, focusing on links between diversity and trophic interactions, and on links between regional diversity, local diversity, and ecosystem processes. Maintaining biodiversity and biocomplexity of seagrass and other coastal ecosystems has important conservation and management implications. © Inter-Research 2006.},\n\tauthor = {Duffy, J. Emmett},\n\tyear = {2006},\n\tdoi = {10.3354/meps311233},\n\tnote = {Publication Title: Marine Ecology Progress Series},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Biodiversity at multiple levels - genotypes within species, species within functional groups, habitats within a landscape - enhances productivity, resource use, and stability of seagrass ecosystems. Several themes emerge from a review of the mostly indirect evidence and the few experiments that explicitly manipulated diversity in seagrass systems. First, because many seagrass communities are dominated by 1 or a few plant species, genetic and phenotypic diversity within such foundation species has important influences on ecosystem productivity and stability. Second, in seagrass beds and many other aquatic systems, consumer control is strong, extinction is biased toward large body size and high trophic levels, and thus human impacts are often mediated by interactions of changing 'vertical diversity' (food chain length) with changing 'horizontal diversity' (heterogeneity within trophic levels). Third, the openness of marine systems means that ecosystem structure and processes often depend on interactions among habitats within a landscape (landscape diversity). There is clear evidence from seagrass systems that advection of resources and active movement of consumers among adjacent habitats influence nutrient fluxes, trophic transfer, fishery production, and species diversity. Future investigations of biodiversity effects on processes within seagrass and other aquatic ecosystems would benefit from broadening the concept of biodiversity to encompass the hierarchy of genetic through landscape diversity, focusing on links between diversity and trophic interactions, and on links between regional diversity, local diversity, and ecosystem processes. Maintaining biodiversity and biocomplexity of seagrass and other coastal ecosystems has important conservation and management implications. © Inter-Research 2006.\n
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\n \n\n \n \n \n \n \n Effects of biodiversity on the functioning of trophic groups and ecosystems.\n \n \n \n\n\n \n Cardinale, B. J.; Srivastava, D. S.; Duffy, J. E.; Wright, J. P.; Downing, A. L.; Sankaran, M.; and Jouseau, C.\n\n\n \n\n\n\n Nature. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{cardinale_effects_2006,\n\ttitle = {Effects of biodiversity on the functioning of trophic groups and ecosystems},\n\tdoi = {10.1038/nature05202},\n\tabstract = {Over the past decade, accelerating rates of species extinction have prompted an increasing number of studies to reduce species diversity experimentally and examine how this alters the efficiency by which communities capture resources and convert those into biomass. So far, the generality of patterns and processes observed in individual studies have been the subjects of considerable debate. Here we present a formal meta-analysis of studies that have experimentally manipulated species diversity to examine how it affects the functioning of numerous trophic groups in multiple types of ecosystem. We show that the average effect of decreasing species richness is to decrease the abundance or biomass of the focal trophic group, leading to less complete depletion of resources used by that group. At the same time, analyses reveal that the standing stock of, and resource depletion by, the most species-rich polyculture tends to be no different from that of the single most productive species used in an experiment. Of the known mechanisms that might explain these trends, results are most consistent with what is called the 'sampling effect', which occurs when diverse communities are more likely to contain and become dominated by the most productive species. Whether this mechanism is widespread in natural communities is currently controversial. Patterns we report are remarkably consistent for four different trophic groups (producers, herbivores, detritivores and predators) and two major ecosystem types (aquatic and terrestrial). Collectively, our analyses suggest that the average species loss does indeed affect the functioning of a wide variety of organisms and ecosystems, but the magnitude of these effects is ultimately determined by the identity of species that are going extinct. ©2006 Nature Publishing Group.},\n\tjournal = {Nature},\n\tauthor = {Cardinale, Bradley J. and Srivastava, Diane S. and Duffy, J. Emmett and Wright, Justin P. and Downing, Amy L. and Sankaran, Mahesh and Jouseau, Claire},\n\tyear = {2006},\n\tpmid = {17066035},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Over the past decade, accelerating rates of species extinction have prompted an increasing number of studies to reduce species diversity experimentally and examine how this alters the efficiency by which communities capture resources and convert those into biomass. So far, the generality of patterns and processes observed in individual studies have been the subjects of considerable debate. Here we present a formal meta-analysis of studies that have experimentally manipulated species diversity to examine how it affects the functioning of numerous trophic groups in multiple types of ecosystem. We show that the average effect of decreasing species richness is to decrease the abundance or biomass of the focal trophic group, leading to less complete depletion of resources used by that group. At the same time, analyses reveal that the standing stock of, and resource depletion by, the most species-rich polyculture tends to be no different from that of the single most productive species used in an experiment. Of the known mechanisms that might explain these trends, results are most consistent with what is called the 'sampling effect', which occurs when diverse communities are more likely to contain and become dominated by the most productive species. Whether this mechanism is widespread in natural communities is currently controversial. Patterns we report are remarkably consistent for four different trophic groups (producers, herbivores, detritivores and predators) and two major ecosystem types (aquatic and terrestrial). Collectively, our analyses suggest that the average species loss does indeed affect the functioning of a wide variety of organisms and ecosystems, but the magnitude of these effects is ultimately determined by the identity of species that are going extinct. ©2006 Nature Publishing Group.\n
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\n \n\n \n \n \n \n \n Can otolith chemistry be used for identifying essential seagrass habitats for juvenile spotted seatrout, Cynoscion nebulosus, in Chesapeake Bay?.\n \n \n \n\n\n \n Dorval, E.; Jones, C. M.; Hannigar, R.; and Van Montfrans, J.\n\n\n \n\n\n\n In Marine and Freshwater Research, 2005. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@inproceedings{dorval_can_2005,\n\ttitle = {Can otolith chemistry be used for identifying essential seagrass habitats for juvenile spotted seatrout, {Cynoscion} nebulosus, in {Chesapeake} {Bay}?},\n\tdoi = {10.1071/MF04179},\n\tabstract = {We investigated the variability of otolith chemistry in juvenile spotted seatrout from Chesapeake Bay seagrass habitats in 1998 and 2001, to assess whether otolith elemental and isotopic composition could be used to identify the most essential seagrass habitats for those juvenile fish. Otolith chemistry (Ca, Mn, Sr, Ba, and La; δ13C, δ18O) of juvenile fish collected in the five major seagrass habitats (Potomac, Rappahannock, York, Island, and Pocomoke Sound) showed significant variability within and between years. Although the ability of trace elements to allocate individual fish may vary between years, in combination with stable isotopes, they achieve high classification accuracy averaging 80-82\\% in the Pocomoke Sound and the Island, and 95-100\\% in the York and the Potomac habitats. The trace elements (Mn, Ba, and La) provided the best discrimination in 2001, a year of lower freshwater discharge than 1998. This is the first application of a rare earth element measured in otoliths (La) to discriminate habitats, and identify seagrass habitats for juvenile spotted seatrout at spatial scales of 15 km. Such fine spatial scale discrimination of habitats has not been previously achieved in estuaries and will distinguish fish born in individual seagrass beds in the Bay. © CSIRO 2005.},\n\tbooktitle = {Marine and {Freshwater} {Research}},\n\tauthor = {Dorval, Emmanis and Jones, Cynthia M. and Hannigar, Robyn and Van Montfrans, Jacques},\n\tyear = {2005},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n We investigated the variability of otolith chemistry in juvenile spotted seatrout from Chesapeake Bay seagrass habitats in 1998 and 2001, to assess whether otolith elemental and isotopic composition could be used to identify the most essential seagrass habitats for those juvenile fish. Otolith chemistry (Ca, Mn, Sr, Ba, and La; δ13C, δ18O) of juvenile fish collected in the five major seagrass habitats (Potomac, Rappahannock, York, Island, and Pocomoke Sound) showed significant variability within and between years. Although the ability of trace elements to allocate individual fish may vary between years, in combination with stable isotopes, they achieve high classification accuracy averaging 80-82% in the Pocomoke Sound and the Island, and 95-100% in the York and the Potomac habitats. The trace elements (Mn, Ba, and La) provided the best discrimination in 2001, a year of lower freshwater discharge than 1998. This is the first application of a rare earth element measured in otoliths (La) to discriminate habitats, and identify seagrass habitats for juvenile spotted seatrout at spatial scales of 15 km. Such fine spatial scale discrimination of habitats has not been previously achieved in estuaries and will distinguish fish born in individual seagrass beds in the Bay. © CSIRO 2005.\n
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\n \n\n \n \n \n \n \n Ecosystem consequences of diversity depend on food chain length in estuarine vegetation.\n \n \n \n\n\n \n Duffy, J. E.; Richardson, J. P.; and France, K. E.\n\n\n \n\n\n\n Ecology Letters. 2005.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{duffy_ecosystem_2005,\n\ttitle = {Ecosystem consequences of diversity depend on food chain length in estuarine vegetation},\n\tdoi = {10.1111/j.1461-0248.2005.00725.x},\n\tabstract = {Biodiversity and food chain length each can strongly influence ecosystem functioning, yet their interactions rarely have been tested. We manipulated grazer diversity in seagrass mesocosms with and without a generalist predator and monitored community development. Changing food chain length altered biodiversity effects: higher grazer diversity enhanced secondary production, epiphyte grazing, and seagrass biomass only with predators present. Conversely, changing diversity altered top-down control: predator impacts on grazer and seagrass biomass were weaker in mixed-grazer assemblages. These interactions resulted in part from among-species trade-offs between predation resistance and competitive ability. Despite weak impact on grazer abundance at high diversity, predators nevertheless enhanced algal biomass through a behaviourally mediated trophic cascade. Moreover, predators influenced every measured variable except total plant biomass, suggesting that the latter is an insensitive metric of ecosystem functioning. Thus, biodiversity and trophic structure interactively influence ecosystem functioning, and neither factor's impact is predictable in isolation. ©2005 Blackwell Publishing Ltd/CNRS.},\n\tjournal = {Ecology Letters},\n\tauthor = {Duffy, J. Emmett and Richardson, J. Paul and France, Kristin E.},\n\tyear = {2005},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Biodiversity and food chain length each can strongly influence ecosystem functioning, yet their interactions rarely have been tested. We manipulated grazer diversity in seagrass mesocosms with and without a generalist predator and monitored community development. Changing food chain length altered biodiversity effects: higher grazer diversity enhanced secondary production, epiphyte grazing, and seagrass biomass only with predators present. Conversely, changing diversity altered top-down control: predator impacts on grazer and seagrass biomass were weaker in mixed-grazer assemblages. These interactions resulted in part from among-species trade-offs between predation resistance and competitive ability. Despite weak impact on grazer abundance at high diversity, predators nevertheless enhanced algal biomass through a behaviourally mediated trophic cascade. Moreover, predators influenced every measured variable except total plant biomass, suggesting that the latter is an insensitive metric of ecosystem functioning. Thus, biodiversity and trophic structure interactively influence ecosystem functioning, and neither factor's impact is predictable in isolation. ©2005 Blackwell Publishing Ltd/CNRS.\n
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\n \n\n \n \n \n \n \n Density, abundance and survival of the blue crab in seagrass and unstructured salt marsh nurseries of Chesapeake Bay.\n \n \n \n\n\n \n Lipcius, R. N.; Seitz, R. D.; Seebo, M. S.; and Colón-Carrión, D.\n\n\n \n\n\n\n In Journal of Experimental Marine Biology and Ecology, 2005. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@inproceedings{lipcius_density_2005,\n\ttitle = {Density, abundance and survival of the blue crab in seagrass and unstructured salt marsh nurseries of {Chesapeake} {Bay}},\n\tdoi = {10.1016/j.jembe.2004.12.034},\n\tabstract = {Structured benthic habitats such as salt marshes, seagrass beds and oyster reefs are recognized as critical nurseries for fish, crustaceans and mollusks in coastal and estuarine systems. Yet most estuaries and coastal habitats have extensive, relatively unstructured shallow-water habitats such as subtidal mud and sand flats, which are generally viewed as inconsequential nursery grounds. We tested this paradigm with the blue crab, Callinectes sapidus Rathbun, in shallow and deep benthic habitats of the York River, Chesapeake Bay. Juvenile blue crabs ({\\textbackslash}textless100 mm carapace width) were sampled quantitatively in deep channel muds (DCM, {\\textbackslash}textgreater2 m depth), in shallow unstructured subtidal mud flats (SMF) and sand flats (SSF) adjoining salt marshes, and in beds of submerged aquatic vegetation (SAV-eelgrass, Zostera marina, and widgeongrass, Ruppia maritime) in three river zones (Upriver, Downriver, Mouth) across 60 km of the river axis. Survival of juveniles 25-55 mm carapace width was examined experimentally in all shallow habitats. SAV habitats were examined only at the Mouth zone; SAV did not occur in the Downriver and Upriver zones. Juvenile blue crab density was nearly an order of magnitude lower in SMF and SSF than in SAV habitats; density was lowest in DCM. Density in Upriver SMF and SSF habitats was 4- to 10-fold higher than that in Mouth and Downriver SMF and SSF, and DCM. Consequently, the two areas harboring the greatest fractions of York River juveniles were shallow: Mouth SAV (∼50\\%) and Upriver SMF and SSF (∼40\\%). Upriver expanses of SMF and SSF adjoining extensive salt marshes near the turbidity maximum harbored an approximately equal abundance of juvenile crabs as the downriver SAV beds, despite the density difference. Survival of tethered juveniles was significantly higher in Upriver SMF and SSF habitats than in Mouth SAV, SMF and SSF habitats, despite the lack of structural refuge in SMF and SSF; crabs in Upriver SMF and SSF survived four times as long as crabs in SAV, Mouth SMF and Mouth SSF. We conclude that shallow subtidal mud and sand flats near upriver salt marshes and in marsh coves are vital nursery grounds for the blue crab, and thus warrant conservation and restoration efforts at the level provided to SAV. The production potential of the blue crab and other estuarine species that utilize salt marshes has likely been severely reduced due not only to direct salt marsh destruction, but also due to indirect degradation of shallow subtidal mud and sand flats fringing salt marshes. © 2005 Elsevier B.V. All rights reserved.},\n\tbooktitle = {Journal of {Experimental} {Marine} {Biology} and {Ecology}},\n\tauthor = {Lipcius, Romuald N. and Seitz, Rochelle D. and Seebo, Michael S. and Colón-Carrión, Duamed},\n\tyear = {2005},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n\n\n
\n Structured benthic habitats such as salt marshes, seagrass beds and oyster reefs are recognized as critical nurseries for fish, crustaceans and mollusks in coastal and estuarine systems. Yet most estuaries and coastal habitats have extensive, relatively unstructured shallow-water habitats such as subtidal mud and sand flats, which are generally viewed as inconsequential nursery grounds. We tested this paradigm with the blue crab, Callinectes sapidus Rathbun, in shallow and deep benthic habitats of the York River, Chesapeake Bay. Juvenile blue crabs (\\textless100 mm carapace width) were sampled quantitatively in deep channel muds (DCM, \\textgreater2 m depth), in shallow unstructured subtidal mud flats (SMF) and sand flats (SSF) adjoining salt marshes, and in beds of submerged aquatic vegetation (SAV-eelgrass, Zostera marina, and widgeongrass, Ruppia maritime) in three river zones (Upriver, Downriver, Mouth) across 60 km of the river axis. Survival of juveniles 25-55 mm carapace width was examined experimentally in all shallow habitats. SAV habitats were examined only at the Mouth zone; SAV did not occur in the Downriver and Upriver zones. Juvenile blue crab density was nearly an order of magnitude lower in SMF and SSF than in SAV habitats; density was lowest in DCM. Density in Upriver SMF and SSF habitats was 4- to 10-fold higher than that in Mouth and Downriver SMF and SSF, and DCM. Consequently, the two areas harboring the greatest fractions of York River juveniles were shallow: Mouth SAV (∼50%) and Upriver SMF and SSF (∼40%). Upriver expanses of SMF and SSF adjoining extensive salt marshes near the turbidity maximum harbored an approximately equal abundance of juvenile crabs as the downriver SAV beds, despite the density difference. Survival of tethered juveniles was significantly higher in Upriver SMF and SSF habitats than in Mouth SAV, SMF and SSF habitats, despite the lack of structural refuge in SMF and SSF; crabs in Upriver SMF and SSF survived four times as long as crabs in SAV, Mouth SMF and Mouth SSF. We conclude that shallow subtidal mud and sand flats near upriver salt marshes and in marsh coves are vital nursery grounds for the blue crab, and thus warrant conservation and restoration efforts at the level provided to SAV. The production potential of the blue crab and other estuarine species that utilize salt marshes has likely been severely reduced due not only to direct salt marsh destruction, but also due to indirect degradation of shallow subtidal mud and sand flats fringing salt marshes. © 2005 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Food availability and growth of the blue crab in seagrass and unvegetated nurseries of Chesapeake Bay.\n \n \n \n\n\n \n Seitz, R. D.; Lipcius, R. N.; and Seebo, M. S.\n\n\n \n\n\n\n In Journal of Experimental Marine Biology and Ecology, 2005. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@inproceedings{seitz_food_2005,\n\ttitle = {Food availability and growth of the blue crab in seagrass and unvegetated nurseries of {Chesapeake} {Bay}},\n\tdoi = {10.1016/j.jembe.2004.10.013},\n\tabstract = {Variation in habitat quality and resource availability can affect the distribution and growth of animals. Thin-shelled clams dominate many benthic communities in Chesapeake Bay, both in numbers and in biomass, and they can comprise up to 50\\% of the blue crab (Callinectes sapidus) diet. Our objective was to determine which habitats were optimal for juvenile crab growth and how growth related to food availability. We experimentally examined benthic infaunal food availability (primarily bivalves) and concurrent growth of juvenile blue crabs at 30-40 sites along 50 km of the York River during fall 2000 and spring 2001. Each year, 4-10 replicate sites along the York River were established in each of five habitats: (1) Seagrass, (2) Mud at the river mouth, (3) Sand at the river mouth, (4) Mud upriver, and (5) Sand upriver. Food availability inside and outside of 0.43-m2 crab growth cages was examined, along with crab growth after 3-6 months inside cages. In both years, after 3-6 months, the Baltic clam, Macoma balthica, was abundant inside and outside the cages, whereas the soft-shell clam, Mya arenaria, was only abundant inside cages. Densities of Macoma were greatest in upriver mud and sand, while those of Mya were greatest in upriver sand. Crab growth was significantly greater in spring-summer than fall-winter and was significantly higher in upriver mud and sand, where clam densities were highest, than at the river mouth. The upriver region was near the turbidity maximum, which may enhance pelagic and benthic productivity and thereby provide more food for clams and therefore for blue crabs. Crab growth in seagrass was intermediate between that upriver and at the mouth, suggesting that upriver, unvegetated, subtidal habitats adjacent to salt marshes serve as valuable nursery habitats rivaling seagrass beds. © 2005 Elsevier B.V. All rights reserved.},\n\tbooktitle = {Journal of {Experimental} {Marine} {Biology} and {Ecology}},\n\tauthor = {Seitz, Rochelle D. and Lipcius, Romuald N. and Seebo, Michael S.},\n\tyear = {2005},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Variation in habitat quality and resource availability can affect the distribution and growth of animals. Thin-shelled clams dominate many benthic communities in Chesapeake Bay, both in numbers and in biomass, and they can comprise up to 50% of the blue crab (Callinectes sapidus) diet. Our objective was to determine which habitats were optimal for juvenile crab growth and how growth related to food availability. We experimentally examined benthic infaunal food availability (primarily bivalves) and concurrent growth of juvenile blue crabs at 30-40 sites along 50 km of the York River during fall 2000 and spring 2001. Each year, 4-10 replicate sites along the York River were established in each of five habitats: (1) Seagrass, (2) Mud at the river mouth, (3) Sand at the river mouth, (4) Mud upriver, and (5) Sand upriver. Food availability inside and outside of 0.43-m2 crab growth cages was examined, along with crab growth after 3-6 months inside cages. In both years, after 3-6 months, the Baltic clam, Macoma balthica, was abundant inside and outside the cages, whereas the soft-shell clam, Mya arenaria, was only abundant inside cages. Densities of Macoma were greatest in upriver mud and sand, while those of Mya were greatest in upriver sand. Crab growth was significantly greater in spring-summer than fall-winter and was significantly higher in upriver mud and sand, where clam densities were highest, than at the river mouth. The upriver region was near the turbidity maximum, which may enhance pelagic and benthic productivity and thereby provide more food for clams and therefore for blue crabs. Crab growth in seagrass was intermediate between that upriver and at the mouth, suggesting that upriver, unvegetated, subtidal habitats adjacent to salt marshes serve as valuable nursery habitats rivaling seagrass beds. © 2005 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Critical evaluation of the nursery role hypothesis for seagrass meadows.\n \n \n \n\n\n \n Heck, K. L.; Hays, G.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{heck_critical_2003,\n\ttitle = {Critical evaluation of the nursery role hypothesis for seagrass meadows},\n\tdoi = {10.3354/meps253123},\n\tabstract = {The vast majority of published papers concerning seagrass meadows contain statements to the effect that seagrass beds serve as important nurseries for many species. We reviewed more than 200 papers that were relevant to the nursery role hypothesis. We used both vote counting and meta-analytic techniques to evaluate whether the body of previous studies that report seagrass meadows to be nursery grounds actually contain data that support this proposition. We restricted our analyses to papers that compared seagrass beds to other habitats, and examined data on a variety of well-studied species concerning their density, growth, survival and migration to adult habitat. Within this group of papers, we considered potential factors that could influence the nursery function (e.g. location, or laboratory vs field studies). We also evaluated case histories of well-documented large-scale seagrass losses on the nursery function. Major results were consistent with the expectations that abundance, growth and survival were greater in seagrass than in unstructured habitats. Abundance data also suggested that seagrass beds in the Northern Hemisphere might be more important as nursery areas than those in the Southern Hemisphere. Surprisingly, few significant differences existed in abundance, growth or survival when seagrass meadows were compared to other structured habitats, such as oyster or cobble reefs, or macroalgal beds. Nor were there decreases in harvests of commercially important species that could clearly be attributed to significant seagrass declines in 3 well-studied areas. However, there were decreased abundances of juveniles of commercially important species in these areas, suggesting a strong link between seagrass abundance and those of juvenile finfish and shellfish. One important implication of these results is that structure per se, rather than the type of structure, appears to be an important determinant of nursery value. Clearly, more rigorous studies that test all aspects of the nursery role hypothesis are clearly needed for seagrass meadows as well as other structured habitats. The results of such studies will allow better decisions to be made concerning the conservation and restoration of marine habitats.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Heck, K. L. and Hays, G. and Orth, R. J.},\n\tyear = {2003},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n The vast majority of published papers concerning seagrass meadows contain statements to the effect that seagrass beds serve as important nurseries for many species. We reviewed more than 200 papers that were relevant to the nursery role hypothesis. We used both vote counting and meta-analytic techniques to evaluate whether the body of previous studies that report seagrass meadows to be nursery grounds actually contain data that support this proposition. We restricted our analyses to papers that compared seagrass beds to other habitats, and examined data on a variety of well-studied species concerning their density, growth, survival and migration to adult habitat. Within this group of papers, we considered potential factors that could influence the nursery function (e.g. location, or laboratory vs field studies). We also evaluated case histories of well-documented large-scale seagrass losses on the nursery function. Major results were consistent with the expectations that abundance, growth and survival were greater in seagrass than in unstructured habitats. Abundance data also suggested that seagrass beds in the Northern Hemisphere might be more important as nursery areas than those in the Southern Hemisphere. Surprisingly, few significant differences existed in abundance, growth or survival when seagrass meadows were compared to other structured habitats, such as oyster or cobble reefs, or macroalgal beds. Nor were there decreases in harvests of commercially important species that could clearly be attributed to significant seagrass declines in 3 well-studied areas. However, there were decreased abundances of juveniles of commercially important species in these areas, suggesting a strong link between seagrass abundance and those of juvenile finfish and shellfish. One important implication of these results is that structure per se, rather than the type of structure, appears to be an important determinant of nursery value. Clearly, more rigorous studies that test all aspects of the nursery role hypothesis are clearly needed for seagrass meadows as well as other structured habitats. The results of such studies will allow better decisions to be made concerning the conservation and restoration of marine habitats.\n
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\n \n\n \n \n \n \n \n Substrate selection by blue crab Callinectes sapidus megalopae and first juvenile instars.\n \n \n \n\n\n \n Van Montfrans, J.; Ryer, C. H.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{van_montfrans_substrate_2003,\n\ttitle = {Substrate selection by blue crab {Callinectes} sapidus megalopae and first juvenile instars},\n\tdoi = {10.3354/meps260209},\n\tabstract = {Various marine and estuarine species utilize chemical cues during settlement. We investigated responses by megalopae and first juvenile (J1) blue crabs to common Chesapeake Bay substrates in mesocosm and field experiments. Mesocosm trials examined responses of megalopae or J1 crabs to sand, marsh mud, live oysters Crassostrea virginica, sun-bleached oyster shell, eel grass Zostera marina and artificial seagrass in replicate 160 1 tanks. Either 10 megalopae or J1 crabs isolated in each of 6 substrates were allowed total access after acclimation to test the null hypothesis of equal distribution among substrates after 13 h. Thirty-five percent of megalopae were recovered from Z. marina, with the remaining substrates containing fewer than half that many. In contrast, 30\\% of J1 crabs (with only 17\\% recovered from Z. marina) were found in live C. virginica. A field experiment quantified responses of ingressing megalopae to Z. marina, marsh mud, and C. virginica. Overnight settlement was significantly higher in Z. marina (x̄ = 3.3 ind.; 60\\% of total) when compared to mud (x̄ = 0.9; 16\\%) or C. virginica (x̄ = 1. 3; 24\\%). Likewise, J1 crabs were significantly more numerous in Z. marina (x̄ = 3.7 ind.; 55\\% of total) than in C. virginica (x̄ = 1.8; 27\\%) and mud (x̄ = 1.2; 18\\%). J1 crab distribution in field plots likely reflected habitat selection by megalopae; laboratory results were equivocal and probably due to artifacts associated with density-dependent agonism. The initial non-random distribution of blue crabs in Chesapeake Bay may be deterministic and due to habitatselection behavior by megalopae. Selection for seagrass assures the greatest likelihood of maximal survival and accelerated growth. Similar relationships may also exist in estuarine-dependent species with comparable habitat requirements and life-history characteristics.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Van Montfrans, Jacques and Ryer, Clifford H. and Orth, Robert J.},\n\tyear = {2003},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Various marine and estuarine species utilize chemical cues during settlement. We investigated responses by megalopae and first juvenile (J1) blue crabs to common Chesapeake Bay substrates in mesocosm and field experiments. Mesocosm trials examined responses of megalopae or J1 crabs to sand, marsh mud, live oysters Crassostrea virginica, sun-bleached oyster shell, eel grass Zostera marina and artificial seagrass in replicate 160 1 tanks. Either 10 megalopae or J1 crabs isolated in each of 6 substrates were allowed total access after acclimation to test the null hypothesis of equal distribution among substrates after 13 h. Thirty-five percent of megalopae were recovered from Z. marina, with the remaining substrates containing fewer than half that many. In contrast, 30% of J1 crabs (with only 17% recovered from Z. marina) were found in live C. virginica. A field experiment quantified responses of ingressing megalopae to Z. marina, marsh mud, and C. virginica. Overnight settlement was significantly higher in Z. marina (x̄ = 3.3 ind.; 60% of total) when compared to mud (x̄ = 0.9; 16%) or C. virginica (x̄ = 1. 3; 24%). Likewise, J1 crabs were significantly more numerous in Z. marina (x̄ = 3.7 ind.; 55% of total) than in C. virginica (x̄ = 1.8; 27%) and mud (x̄ = 1.2; 18%). J1 crab distribution in field plots likely reflected habitat selection by megalopae; laboratory results were equivocal and probably due to artifacts associated with density-dependent agonism. The initial non-random distribution of blue crabs in Chesapeake Bay may be deterministic and due to habitatselection behavior by megalopae. Selection for seagrass assures the greatest likelihood of maximal survival and accelerated growth. Similar relationships may also exist in estuarine-dependent species with comparable habitat requirements and life-history characteristics.\n
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\n \n\n \n \n \n \n \n Grazer diversity effects on ecosystem functioning in seagrass beds.\n \n \n \n\n\n \n Duffy, J. E.; Richardson, J. P.; and Canuel, E. A.\n\n\n \n\n\n\n Ecology Letters. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{duffy_grazer_2003,\n\ttitle = {Grazer diversity effects on ecosystem functioning in seagrass beds},\n\tdoi = {10.1046/j.1461-0248.2003.00474.x},\n\tabstract = {High plant species richness can enhance primary production, animal diversity, and invasion resistance. Yet theory predicts that plant and herbivore diversity, which often covary in nature, should have countervailing effects on ecosystem properties. Supporting this, we show in a seagrass system that increasing grazer diversity reduced both algal biomass and total community diversity, and facilitated dominance of a grazer-resistant invertebrate. In parallel with previous plant results, however, grazer diversity enhanced secondary production, a critical determinant of fish yield. Although sampling explained some diversity effects, only the most diverse grazer assemblage maximized multiple ecosystem properties simultaneously, producing a distinct ecosystem state. Importantly, ecosystem responses at high grazer diversity often differed in magnitude and sign from those predicted from summed impacts of individual species. Thus, complex interactions, often opposing plant diversity effects, arose as emergent consequences of changing consumer diversity, advising caution in extrapolating conclusions from plant diversity experiments to food webs.},\n\tjournal = {Ecology Letters},\n\tauthor = {Duffy, J. Emmett and Richardson, J. Paul and Canuel, Elizabeth A.},\n\tyear = {2003},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n High plant species richness can enhance primary production, animal diversity, and invasion resistance. Yet theory predicts that plant and herbivore diversity, which often covary in nature, should have countervailing effects on ecosystem properties. Supporting this, we show in a seagrass system that increasing grazer diversity reduced both algal biomass and total community diversity, and facilitated dominance of a grazer-resistant invertebrate. In parallel with previous plant results, however, grazer diversity enhanced secondary production, a critical determinant of fish yield. Although sampling explained some diversity effects, only the most diverse grazer assemblage maximized multiple ecosystem properties simultaneously, producing a distinct ecosystem state. Importantly, ecosystem responses at high grazer diversity often differed in magnitude and sign from those predicted from summed impacts of individual species. Thus, complex interactions, often opposing plant diversity effects, arose as emergent consequences of changing consumer diversity, advising caution in extrapolating conclusions from plant diversity experiments to food webs.\n
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\n \n\n \n \n \n \n \n The response of fishes to submerged aquatic vegetation complexity in two ecoregions of the Mid-Atlantic Bight: Buzzards Bay and Chesapeake Bay.\n \n \n \n\n\n \n Wyda, J. C.; Deegan, L. A.; Hughes, J. E.; and Weaver, M. J.\n\n\n \n\n\n\n Estuaries. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{wyda_response_2002,\n\ttitle = {The response of fishes to submerged aquatic vegetation complexity in two ecoregions of the {Mid}-{Atlantic} {Bight}: {Buzzards} {Bay} and {Chesapeake} {Bay}},\n\tdoi = {10.1007/BF02696052},\n\tabstract = {Estuarine seagrass ecosystems provide important habitat for fish and invertebrates and changes in these systems may alter their ability to support fish. The response of fish assemblages to alteration of eelgrass (Zostera marina) ecosystems in two ecoregions of the Mid-Atlantic Bight (Buzzards Bay and Chesapeake Bay) was evaluated by sampling historical eelgrass sites that currently span a broad range of stress and habitat quality. In two widely separated ecoregions with very different fish faunas, degradation and loss of submerged aquatic vegetation (SAV) habitat has lead to declines in fish standing stock and species richness. The abundance, biomass, and species richness of the fish assemblage were significantly higher at sites that have high levels of eelgrass habitat complexity (biomass {\\textbackslash}textgreater 100 wet g m-2; density {\\textbackslash}textgreater 100 shoots m-2) compared to sites that have reduced eelgrass (biomass {\\textbackslash}textless 100 wet g m-2; density {\\textbackslash}textless 100 shoots m-2) or that have completely lost eelgrass. Abundance, biomass, and species richness at reduced eelgrass complexity sites also were more variable than at high eelgrass complexity habitats. Low SAV complexity sites had higher proportions of pelagic species that are not dependent on benthic habitat structure for feeding or refuge. Most species had greater abundance and were found more frequently at sites that have eelgrass. The replacement of SAV habitats by benthic macroalgae, which occurred in Buzzards Bay but not Chesapeake Bay, did not provide an equivalent habitat to seagrass. Nutrient enrichment-related degradation of eelgrass habitat has diminished the overall capacity of estuaries to support fish populations.},\n\tjournal = {Estuaries},\n\tauthor = {Wyda, Jason C. and Deegan, Linda A. and Hughes, Jeffrey E. and Weaver, Melissa J.},\n\tyear = {2002},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Estuarine seagrass ecosystems provide important habitat for fish and invertebrates and changes in these systems may alter their ability to support fish. The response of fish assemblages to alteration of eelgrass (Zostera marina) ecosystems in two ecoregions of the Mid-Atlantic Bight (Buzzards Bay and Chesapeake Bay) was evaluated by sampling historical eelgrass sites that currently span a broad range of stress and habitat quality. In two widely separated ecoregions with very different fish faunas, degradation and loss of submerged aquatic vegetation (SAV) habitat has lead to declines in fish standing stock and species richness. The abundance, biomass, and species richness of the fish assemblage were significantly higher at sites that have high levels of eelgrass habitat complexity (biomass \\textgreater 100 wet g m-2; density \\textgreater 100 shoots m-2) compared to sites that have reduced eelgrass (biomass \\textless 100 wet g m-2; density \\textless 100 shoots m-2) or that have completely lost eelgrass. Abundance, biomass, and species richness at reduced eelgrass complexity sites also were more variable than at high eelgrass complexity habitats. Low SAV complexity sites had higher proportions of pelagic species that are not dependent on benthic habitat structure for feeding or refuge. Most species had greater abundance and were found more frequently at sites that have eelgrass. The replacement of SAV habitats by benthic macroalgae, which occurred in Buzzards Bay but not Chesapeake Bay, did not provide an equivalent habitat to seagrass. Nutrient enrichment-related degradation of eelgrass habitat has diminished the overall capacity of estuaries to support fish populations.\n
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\n \n\n \n \n \n \n \n Habitat quality and prey size as determinants of survival in post-larval and early juvenile instars of the blue crab Callinectes sapidus.\n \n \n \n\n\n \n Orth, R. J.; and Van Montfrans, J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_habitat_2002,\n\ttitle = {Habitat quality and prey size as determinants of survival in post-larval and early juvenile instars of the blue crab {Callinectes} sapidus},\n\tdoi = {10.3354/meps231205},\n\tabstract = {Habitat structure and prey size are important determinants in the outcome of predator-prey interactions. We investigated the role of simulated habitat type and density (simulated Zostera marina [hereafter referred to as 'Zostera']: 500 and 1500 shoots m-2, and simulated Spartina alterniflora [hereafter referred to as 'Spartina']: 97 and 291 shoots m-2) in mediating predator-prey interactions. Proportional survival during predation by the piscene predator Fundulus heteroclitus on 2 successive life-history stages (post-larvae and first juvenile instars) of the blue crab Callinectes sapidus (Rathbun), was quantified under laboratory conditions that closely approximated field conditions. We also examined the effects of juvenile crab size (equal biomass and equal numbers of 2 or 3 prey-size categories, respectively) on survival during adult F. heteroclitus predation in the absence of vegetation. Crab size categories included small (first juvenile instars; 2.1 mm carapace width [cw]), medium (fourth and fifth crab stage juveniles; 6.0 to 9.1 mm cw), and large (sixth and seventh stage juveniles; 9.2 to 12.6 mm cw) in the equal numbers experiments and small and medium crabs for the equal biomass experiment. Mean proportional survival was higher for both life-history stages in simulated Zostera, with first-instars exhibiting higher proportional survival than post-larvae at the experimental densities tested (post-larvae: no grass = 0.23, low-density grass = 0.44, high-density grass = 0.57; first-instars: no grass = 0.47, low-density grass = 0.87 high-density grass = 0.87). Mean proportional survival did not differ significantly among life-history stages in the simulated Spartina treatments, although proportional survival between treatments was higher for first-instars than post-larvae (post-larvae: no Spartina = 0.17, low-density Spartina = 0.18, high-density Spartina = 0.19; first-instars: no Spartina = 0.46, low-density Spartina = 0.43, high-density Spartina = 0.48). Finally, size-refuge experiments with equal numbers or biomass of prey demonstrated significant differences between each size or/and biomass category tested. Crabs exhibited increasing proportional survival with increasing crab size (small = 0.34, medium = 0.66, large = 0.97) or weight (small = 0.18, medium = 0.67) in the presence of F. heteroclitus, suggesting that C. sapidus attains a refuge in size from predation by adult F. heteroclitus at approximately 9.2 to 12.6 mm. Our findings suggest that the influence of habitat structure on crab survival (possibly as a function of surface area) varies with simulated habitat type, crab density and crab stage (post-larvae versus first-instar), providing additional evidence of the importance of seagrasses in the early life-history stages of blue crabs.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and Van Montfrans, Jacques},\n\tyear = {2002},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Habitat structure and prey size are important determinants in the outcome of predator-prey interactions. We investigated the role of simulated habitat type and density (simulated Zostera marina [hereafter referred to as 'Zostera']: 500 and 1500 shoots m-2, and simulated Spartina alterniflora [hereafter referred to as 'Spartina']: 97 and 291 shoots m-2) in mediating predator-prey interactions. Proportional survival during predation by the piscene predator Fundulus heteroclitus on 2 successive life-history stages (post-larvae and first juvenile instars) of the blue crab Callinectes sapidus (Rathbun), was quantified under laboratory conditions that closely approximated field conditions. We also examined the effects of juvenile crab size (equal biomass and equal numbers of 2 or 3 prey-size categories, respectively) on survival during adult F. heteroclitus predation in the absence of vegetation. Crab size categories included small (first juvenile instars; 2.1 mm carapace width [cw]), medium (fourth and fifth crab stage juveniles; 6.0 to 9.1 mm cw), and large (sixth and seventh stage juveniles; 9.2 to 12.6 mm cw) in the equal numbers experiments and small and medium crabs for the equal biomass experiment. Mean proportional survival was higher for both life-history stages in simulated Zostera, with first-instars exhibiting higher proportional survival than post-larvae at the experimental densities tested (post-larvae: no grass = 0.23, low-density grass = 0.44, high-density grass = 0.57; first-instars: no grass = 0.47, low-density grass = 0.87 high-density grass = 0.87). Mean proportional survival did not differ significantly among life-history stages in the simulated Spartina treatments, although proportional survival between treatments was higher for first-instars than post-larvae (post-larvae: no Spartina = 0.17, low-density Spartina = 0.18, high-density Spartina = 0.19; first-instars: no Spartina = 0.46, low-density Spartina = 0.43, high-density Spartina = 0.48). Finally, size-refuge experiments with equal numbers or biomass of prey demonstrated significant differences between each size or/and biomass category tested. Crabs exhibited increasing proportional survival with increasing crab size (small = 0.34, medium = 0.66, large = 0.97) or weight (small = 0.18, medium = 0.67) in the presence of F. heteroclitus, suggesting that C. sapidus attains a refuge in size from predation by adult F. heteroclitus at approximately 9.2 to 12.6 mm. Our findings suggest that the influence of habitat structure on crab survival (possibly as a function of surface area) varies with simulated habitat type, crab density and crab stage (post-larvae versus first-instar), providing additional evidence of the importance of seagrasses in the early life-history stages of blue crabs.\n
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\n \n\n \n \n \n \n \n Effects of seagrass habitat fragmentation on juvenile blue crab survival and abundance.\n \n \n \n\n\n \n Jompa, J.; and McCook, L. J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{jompa_effects_2002,\n\ttitle = {Effects of seagrass habitat fragmentation on juvenile blue crab survival and abundance},\n\tdoi = {10.1016/S0022-0981(02)00043-6},\n\tabstract = {Seagrasses form temporally dynamic, fragmented subtidal landscapes in which both large- and small-scale habitat structure may influence faunal survival and abundance. We compared the relative influences of seagrass (Zostera marina L.) habitat fragmentation (patch size and isolation) and structural complexity (shoot density) on juvenile blue crab (Callinectes sapidus Rathbun) survival and density in a Chesapeake Bay seagrass meadow. We tethered crabs to measure relative survival, suction sampled for crabs to measure density, and took seagrass cores to measure shoot density in patches spanning six orders of magnitude (ca. 0.25-30,000 m2) both before (June) and after (September) seasonally predictable decreases in seagrass structural complexity and increases in seagrass fragmentation. We also determined if juvenile blue crab density and seagrass shoot density varied between the edge and the interior of patches. In June, juvenile blue crab survival was not linearly related to seagrass patch size or to shoot density, but was significantly lower in patches separated by large expanses of unvegetated sediment (isolated patches) than in patches separated by {\\textbackslash}textless 1 m of unvegetated sediment (connected patches). In September, crab survival was inversely correlated with seagrass shoot density. This inverse correlation was likely due to density-dependent predation by juvenile conspecifics (i.e. cannibalism); juvenile blue crab density increased with seagrass shoot density, was inversely correlated with crab survival, and was greater in September than in June. Shoot density effects on predator behavior and on conspecific density also likely caused crab survival to be lower in isolated patches than in connected patches in June. Isolated patches were either large (patch area {\\textbackslash}textgreater 3000 m2) or very small ({\\textbackslash}textless 1 m2). Large isolated patches had the lowest shoot densities, which may have allowed predators to easily find tethered crabs. Very small isolated patches had the highest shoot densities and consequently a high abundance of predators (= juvenile conspecifics). Though shoot density did not differ between the edge and the interior of patches, crabs were more abundant in the interior of patches than at the edge. These results indicate that seagrass fragmentation does not have an overriding influence on juvenile blue crab survival and density, and that crab cannibalism and seasonal changes in landscape structure may influence relationships between crab survival and seagrass habitat structure. Habitat fragmentation, structural complexity, faunal density, and time all must be incorporated into future studies on faunal survival in seagrass landscapes. © 2002 Elsevier Science B.V. All rights reserved.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Jompa, Jamaluddin and McCook, Laurence J.},\n\tyear = {2002},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n Seagrasses form temporally dynamic, fragmented subtidal landscapes in which both large- and small-scale habitat structure may influence faunal survival and abundance. We compared the relative influences of seagrass (Zostera marina L.) habitat fragmentation (patch size and isolation) and structural complexity (shoot density) on juvenile blue crab (Callinectes sapidus Rathbun) survival and density in a Chesapeake Bay seagrass meadow. We tethered crabs to measure relative survival, suction sampled for crabs to measure density, and took seagrass cores to measure shoot density in patches spanning six orders of magnitude (ca. 0.25-30,000 m2) both before (June) and after (September) seasonally predictable decreases in seagrass structural complexity and increases in seagrass fragmentation. We also determined if juvenile blue crab density and seagrass shoot density varied between the edge and the interior of patches. In June, juvenile blue crab survival was not linearly related to seagrass patch size or to shoot density, but was significantly lower in patches separated by large expanses of unvegetated sediment (isolated patches) than in patches separated by \\textless 1 m of unvegetated sediment (connected patches). In September, crab survival was inversely correlated with seagrass shoot density. This inverse correlation was likely due to density-dependent predation by juvenile conspecifics (i.e. cannibalism); juvenile blue crab density increased with seagrass shoot density, was inversely correlated with crab survival, and was greater in September than in June. Shoot density effects on predator behavior and on conspecific density also likely caused crab survival to be lower in isolated patches than in connected patches in June. Isolated patches were either large (patch area \\textgreater 3000 m2) or very small (\\textless 1 m2). Large isolated patches had the lowest shoot densities, which may have allowed predators to easily find tethered crabs. Very small isolated patches had the highest shoot densities and consequently a high abundance of predators (= juvenile conspecifics). Though shoot density did not differ between the edge and the interior of patches, crabs were more abundant in the interior of patches than at the edge. These results indicate that seagrass fragmentation does not have an overriding influence on juvenile blue crab survival and density, and that crab cannibalism and seasonal changes in landscape structure may influence relationships between crab survival and seagrass habitat structure. Habitat fragmentation, structural complexity, faunal density, and time all must be incorporated into future studies on faunal survival in seagrass landscapes. © 2002 Elsevier Science B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Faunal colonization of artificial seagrass plots: The importance of surface area versus space size relative to body size.\n \n \n \n\n\n \n Bartholomew, A.\n\n\n \n\n\n\n Estuaries. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{bartholomew_faunal_2002,\n\ttitle = {Faunal colonization of artificial seagrass plots: {The} importance of surface area versus space size relative to body size},\n\tdoi = {10.1007/BF02691351},\n\tabstract = {An index of structural habitat complexity was devised: the average inter-structural space size within a habitat/the width of the prey organism of concern (Sp/Py). Prey survivorship should be low at Sp/Py {\\textbackslash}textless 1 as the prey will be effectively excluded from using the habitat as refuge (they cannot maneuver through the spaces). At Sp/Py near to 1, survivorship should be high, as the spaces within the habitat are ideal for the prey and their predators are excluded (assuming they are larger than the prey). As Sp/Py increases, prey survivorship should drop rapidly until reaching a lower plateau where no predators are excluded by the structure. Sp/Py is dimensionless, and is potentially applicable across different scales and habitat types. Some of the predictions of this model were tested using artificial seagrass plots deployed in a seagrass bed in the York River, Virginia. The plots had 5 different structural treatments: control (a base with no ribbon), low, medium and high densities, as well as a heterogeneous treatment (composed of 1/3 low, medium and high density in a single treatment). The abundance of 2 mobile fauna size classes ({\\textbackslash}textless 3.5 mm width and 3.5 to 9.5 mm width) and total species richness were compared among the different density treatments. The abundance of the smaller fauna increased with increasing density, and this response was proportional to the total surface area of the plots. The small fauna apparently did not respond to the smaller, ideal space sizes associated with the higher density plots. The larger fauna responded to the treatments as well, with the highest abundances occurring in the heterogeneous and high density treatments. The larger fauna did not respond to the structure proportional to the surface area within the plots, and it is possible that they responded to the inter-structural space sizes appropriate to their body sizes, although the results do not clearly support this conclusion. The different treatments did not affect species richness when the effect of total abundance on richness was controlled.},\n\tjournal = {Estuaries},\n\tauthor = {Bartholomew, Aaron},\n\tyear = {2002},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n An index of structural habitat complexity was devised: the average inter-structural space size within a habitat/the width of the prey organism of concern (Sp/Py). Prey survivorship should be low at Sp/Py \\textless 1 as the prey will be effectively excluded from using the habitat as refuge (they cannot maneuver through the spaces). At Sp/Py near to 1, survivorship should be high, as the spaces within the habitat are ideal for the prey and their predators are excluded (assuming they are larger than the prey). As Sp/Py increases, prey survivorship should drop rapidly until reaching a lower plateau where no predators are excluded by the structure. Sp/Py is dimensionless, and is potentially applicable across different scales and habitat types. Some of the predictions of this model were tested using artificial seagrass plots deployed in a seagrass bed in the York River, Virginia. The plots had 5 different structural treatments: control (a base with no ribbon), low, medium and high densities, as well as a heterogeneous treatment (composed of 1/3 low, medium and high density in a single treatment). The abundance of 2 mobile fauna size classes (\\textless 3.5 mm width and 3.5 to 9.5 mm width) and total species richness were compared among the different density treatments. The abundance of the smaller fauna increased with increasing density, and this response was proportional to the total surface area of the plots. The small fauna apparently did not respond to the smaller, ideal space sizes associated with the higher density plots. The larger fauna responded to the treatments as well, with the highest abundances occurring in the heterogeneous and high density treatments. The larger fauna did not respond to the structure proportional to the surface area within the plots, and it is possible that they responded to the inter-structural space sizes appropriate to their body sizes, although the results do not clearly support this conclusion. The different treatments did not affect species richness when the effect of total abundance on richness was controlled.\n
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\n \n\n \n \n \n \n \n Habitat fragmentation in a seagrass landscape: Patch size and complexity control blue crab survival.\n \n \n \n\n\n \n Hovel, K. A.; and Lipcius, R. N.\n\n\n \n\n\n\n Ecology. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{hovel_habitat_2001,\n\ttitle = {Habitat fragmentation in a seagrass landscape: {Patch} size and complexity control blue crab survival},\n\tdoi = {10.1890/0012-9658(2001)082[1814:HFIASL]2.0.CO;2},\n\tabstract = {Habitat fragmentation is increasingly common on land and in the sea, leading to small, isolated habitat patches in which ecological processes may differ substantially from those in larger, continuous habitats. Seagrass is a productive but fragmented subtidal habitat that serves as a refuge from predation for many animals because its structural complexity limits the detection and capture of resident prey. The singular influence of seagrass habitat fragmentation (e.g., patch size) on faunal survival is largely unknown and has been difficult to quantify because seagrass habitat complexity (e.g., shoot density) and patch size are often confounded and vary seasonally. In early summer 1998 we quantified the effect of seagrass habitat fragmentation on juvenile blue crab (Callinectes sapidus) survival in the absence of covarying complexity by exposing tethered crabs to predators in density-controlled, artificial eelgrass (Zostera marina) plots embedded within natural seagrass patches of four broad size classes ({\\textbackslash}textless1 m2 to {\\textbackslash}textgreater30000 m2). We repeated this experiment in late summer 1998 with three different shoot densities, after predictable environmental events (defoliation and bioturbation) had increased seagrass habitat fragmentation and decreased shoot density. In early summer, crab survival was inversely correlated with seagrass patch area; survival of juvenile blue crabs increased as patch size decreased, in contrast to patterns typically observed in terrestrial and marine systems. This pattern appears to have been due to low abundance of adult blue crabs, the chief predator of juvenile conspecifics, in small patches. In late summer, blue crab survival was greater than in early summer, and survival increased with artificial seagrass shoot density but did not vary with patch size. The breakdown of the relationship between crab survival and patch size in late summer may have resulted from influx of cownose rays, which fragmented large, continuous patches of seagrass into smaller patches in midsummer, potentially equalizing fragmentation across the seagrass meadow. these results show that (1) fragmented seagrass landscapes hold significant refuge value for juvenile blue crabs, (2) fragmentation and crab survival vary temporally, and (3) crab survival increases with habitat complexity (shoot density) regardless of patch size. the findings indicate that habitat patch size and complexity jointly drive organismal survival, and that their influence differs temporally in this dynamic landscape. Thus, ecological processes are sensitive to landscape structure, and studies of habitat structure should incorporate multiple scales of space and time, as well as potentially confounding structural variables.},\n\tjournal = {Ecology},\n\tauthor = {Hovel, K. A. and Lipcius, R. N.},\n\tyear = {2001},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Habitat fragmentation is increasingly common on land and in the sea, leading to small, isolated habitat patches in which ecological processes may differ substantially from those in larger, continuous habitats. Seagrass is a productive but fragmented subtidal habitat that serves as a refuge from predation for many animals because its structural complexity limits the detection and capture of resident prey. The singular influence of seagrass habitat fragmentation (e.g., patch size) on faunal survival is largely unknown and has been difficult to quantify because seagrass habitat complexity (e.g., shoot density) and patch size are often confounded and vary seasonally. In early summer 1998 we quantified the effect of seagrass habitat fragmentation on juvenile blue crab (Callinectes sapidus) survival in the absence of covarying complexity by exposing tethered crabs to predators in density-controlled, artificial eelgrass (Zostera marina) plots embedded within natural seagrass patches of four broad size classes (\\textless1 m2 to \\textgreater30000 m2). We repeated this experiment in late summer 1998 with three different shoot densities, after predictable environmental events (defoliation and bioturbation) had increased seagrass habitat fragmentation and decreased shoot density. In early summer, crab survival was inversely correlated with seagrass patch area; survival of juvenile blue crabs increased as patch size decreased, in contrast to patterns typically observed in terrestrial and marine systems. This pattern appears to have been due to low abundance of adult blue crabs, the chief predator of juvenile conspecifics, in small patches. In late summer, blue crab survival was greater than in early summer, and survival increased with artificial seagrass shoot density but did not vary with patch size. The breakdown of the relationship between crab survival and patch size in late summer may have resulted from influx of cownose rays, which fragmented large, continuous patches of seagrass into smaller patches in midsummer, potentially equalizing fragmentation across the seagrass meadow. these results show that (1) fragmented seagrass landscapes hold significant refuge value for juvenile blue crabs, (2) fragmentation and crab survival vary temporally, and (3) crab survival increases with habitat complexity (shoot density) regardless of patch size. the findings indicate that habitat patch size and complexity jointly drive organismal survival, and that their influence differs temporally in this dynamic landscape. Thus, ecological processes are sensitive to landscape structure, and studies of habitat structure should incorporate multiple scales of space and time, as well as potentially confounding structural variables.\n
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\n \n\n \n \n \n \n \n Grazer diversity, functional redundancy, and productivity in seagrass beds: An experimental test.\n \n \n \n\n\n \n Duffy, J. E.; Macdonald, K. S.; Rhode, J. M.; and Parker, J. D.\n\n\n \n\n\n\n Ecology. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{duffy_grazer_2001,\n\ttitle = {Grazer diversity, functional redundancy, and productivity in seagrass beds: {An} experimental test},\n\tdoi = {10.1890/0012-9658(2001)082[2417:GDFRAP]2.0.CO;2},\n\tabstract = {Concern over the accelerating loss of biodiversity has stimulated renewed interest in relationships among species richness, species composition, and the functional properties of ecosystems. Mechanistically, the degree of functional differentiation or complementarity among individual species determines the form of such relationships and is thus important to distinguishing among alternative hypotheses for the effects of diversity on ecosystem processes. Although a growing number of studies have reported relationships between plant diversity and ecosystem processes, few have explicitly addressed how functional diversity at higher trophic levels influences ecosystem processes. We used mesocosm experiments to test the impacts of three herbivorous crustacean species (Gammarus mucronatus, Idotea baltica, and Erichsonella attenuata) on plant biomass accumulation, relative dominance of plant functional groups, and herbivore secondary production in beds of eelgrass (Zostera marina), a dominant feature of naturally low-diversity estuaries throughout the northern hemisphere. By establishing treatments with all possible combinations of the three grazer species, we tested the degree of functional redundancy among grazers and their relative impacts on productivity. Grazer species composition strongly influenced eelgrass biomass accumulation and grazer secondary production, whereas none of the processes we studied was clearly related to grazer species richness over the narrow range (0-3 species) studied. In fact, all three measured ecosystem processes - epiphyte grazing, and eelgrass and grazer biomass accumulation - reached highest values in particular single-species treatments. Experimental deletions of individual species from the otherwise-intact assemblage confirmed that the three grazer species were functionally redundant in impacting epiphyte accumulation, whereas secondary production was sensitive to deletion of G. mucronatus, indicating its unique, nonredundant role in influencing this variable. In the field, seasonal abundance patterns differed markedly among the dominant grazer species, suggesting that complementary grazer phenologies may reduce total variance in grazing pressure on an annual basis. Our results show that even superficially similar grazer species can differ in both sign and magnitude of impacts on ecosystem processes and emphasize that one must be cautious in assuming redundancy when assigning species to functional groups.},\n\tjournal = {Ecology},\n\tauthor = {Duffy, J. E. and Macdonald, K. S. and Rhode, J. M. and Parker, J. D.},\n\tyear = {2001},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Concern over the accelerating loss of biodiversity has stimulated renewed interest in relationships among species richness, species composition, and the functional properties of ecosystems. Mechanistically, the degree of functional differentiation or complementarity among individual species determines the form of such relationships and is thus important to distinguishing among alternative hypotheses for the effects of diversity on ecosystem processes. Although a growing number of studies have reported relationships between plant diversity and ecosystem processes, few have explicitly addressed how functional diversity at higher trophic levels influences ecosystem processes. We used mesocosm experiments to test the impacts of three herbivorous crustacean species (Gammarus mucronatus, Idotea baltica, and Erichsonella attenuata) on plant biomass accumulation, relative dominance of plant functional groups, and herbivore secondary production in beds of eelgrass (Zostera marina), a dominant feature of naturally low-diversity estuaries throughout the northern hemisphere. By establishing treatments with all possible combinations of the three grazer species, we tested the degree of functional redundancy among grazers and their relative impacts on productivity. Grazer species composition strongly influenced eelgrass biomass accumulation and grazer secondary production, whereas none of the processes we studied was clearly related to grazer species richness over the narrow range (0-3 species) studied. In fact, all three measured ecosystem processes - epiphyte grazing, and eelgrass and grazer biomass accumulation - reached highest values in particular single-species treatments. Experimental deletions of individual species from the otherwise-intact assemblage confirmed that the three grazer species were functionally redundant in impacting epiphyte accumulation, whereas secondary production was sensitive to deletion of G. mucronatus, indicating its unique, nonredundant role in influencing this variable. In the field, seasonal abundance patterns differed markedly among the dominant grazer species, suggesting that complementary grazer phenologies may reduce total variance in grazing pressure on an annual basis. Our results show that even superficially similar grazer species can differ in both sign and magnitude of impacts on ecosystem processes and emphasize that one must be cautious in assuming redundancy when assigning species to functional groups.\n
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\n \n\n \n \n \n \n \n Species-specific impacts of grazing amphipods in an eelgrass-bed community.\n \n \n \n\n\n \n Duffy, E. J.; and Harvilicz, A. M.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{duffy_species-specific_2001,\n\ttitle = {Species-specific impacts of grazing amphipods in an eelgrass-bed community},\n\tdoi = {10.3354/meps223201},\n\tabstract = {Small, grazing invertebrates often benefit seagrasses by cropping their epiphytic algal competitors. Yet predictive relations between grazer abundance and seagrass performance are elusive, in significant part because of poorly understood diversity in mesograzer feeding biology. We conducted experiments in eelgrass Zostera marina microcosms to explore how differences in feeding between 2 common grazing amphipod taxa affected accumulation and species composition of epiphytes on eelgrass, as well as amphipod population growth, competition and production, over a 4-week period in summer. Gammarus mucronatus and ampithoids (a mixture of Cymadusa compta and Ampithoe longimana) were stocked, singly and in combination, along with a grazer-free control treatment. Amphipod population growth rates indicated that the 2 taxa competed for a common limiting resource, presumably periphyton, which was essentially eliminated in all grazer treatments. Final abundances of both amphipod taxa were 53 to 68\\% lower in treatments where the other grazer was present than in single-species grazer treatments. A common carrying capacity was also indicated by the nearly identical final biomass of amphipods across treatments, despite 2-fold variation in initial amphipod densities. These results support the hypothesis that the 2 amphipod taxa are roughly equivalent in terms of resource requirements and production rates. Despite this equivalence, subtle differences in diet breadth between amphipod taxa translated into substantial differences in biomass and composition of the fouling assemblage among treatments. Whereas grazer-free eelgrass became heavily fouled with periphyton and tunicates, eelgrass exposed to G. mucronatus alone was overgrown by the red alga Polysiphonia harveyi, which reached a biomass equal to the total fouling mass of grazer-free controls. P. harveyi was nearly absent from all other treatments. In contrast, eelgrass with ampithoids was virtually devoid of all fouling material. Thus, similar mesograzer species can have markedly different impacts on fouling assemblages, and these occur despite strong similarity in grazer energetics and primary food sources. Our results may help to reconcile evidence of diet overlap and diffuse competition among mesograzer species with the different feeding preferences and community impacts shown for several mesograzers in experimental studies.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Duffy, Emmett J. and Harvilicz, Annie M.},\n\tyear = {2001},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Small, grazing invertebrates often benefit seagrasses by cropping their epiphytic algal competitors. Yet predictive relations between grazer abundance and seagrass performance are elusive, in significant part because of poorly understood diversity in mesograzer feeding biology. We conducted experiments in eelgrass Zostera marina microcosms to explore how differences in feeding between 2 common grazing amphipod taxa affected accumulation and species composition of epiphytes on eelgrass, as well as amphipod population growth, competition and production, over a 4-week period in summer. Gammarus mucronatus and ampithoids (a mixture of Cymadusa compta and Ampithoe longimana) were stocked, singly and in combination, along with a grazer-free control treatment. Amphipod population growth rates indicated that the 2 taxa competed for a common limiting resource, presumably periphyton, which was essentially eliminated in all grazer treatments. Final abundances of both amphipod taxa were 53 to 68% lower in treatments where the other grazer was present than in single-species grazer treatments. A common carrying capacity was also indicated by the nearly identical final biomass of amphipods across treatments, despite 2-fold variation in initial amphipod densities. These results support the hypothesis that the 2 amphipod taxa are roughly equivalent in terms of resource requirements and production rates. Despite this equivalence, subtle differences in diet breadth between amphipod taxa translated into substantial differences in biomass and composition of the fouling assemblage among treatments. Whereas grazer-free eelgrass became heavily fouled with periphyton and tunicates, eelgrass exposed to G. mucronatus alone was overgrown by the red alga Polysiphonia harveyi, which reached a biomass equal to the total fouling mass of grazer-free controls. P. harveyi was nearly absent from all other treatments. In contrast, eelgrass with ampithoids was virtually devoid of all fouling material. Thus, similar mesograzer species can have markedly different impacts on fouling assemblages, and these occur despite strong similarity in grazer energetics and primary food sources. Our results may help to reconcile evidence of diet overlap and diffuse competition among mesograzer species with the different feeding preferences and community impacts shown for several mesograzers in experimental studies.\n
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\n \n\n \n \n \n \n \n Influence of a tube-dwelling polychaete on the dispersal of fragmented reproductive shoots of eelgrass.\n \n \n \n\n\n \n Parmee, I.; Cvetkovic, D.; Bonham, C.; and Packham, I.\n\n\n \n\n\n\n Aquatic Botany. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{parmee_influence_2001,\n\ttitle = {Influence of a tube-dwelling polychaete on the dispersal of fragmented reproductive shoots of eelgrass},\n\tdoi = {10.1016/S0304-3770(00)00147-9},\n\tabstract = {Diopatra cuprea (Bosc), a common tube-building polychaete, attaches materials such as algae and shell into the wall of its tube cap, in part, to provide a substrate for potential food resources. Reproductive shoots of eelgrass (Zostera marina L.) break off during seed maturation and can be transported by water movement. As these shoots deteriorate, they become neutrally or negatively buoyant and can be transported along the bottom while still carrying seeds. Analysis of 55 l m2 plots along a 100 m transect in the offshore fringe of an eelgrass bed in the York River, Chesapeake Bay, USA, showed that 70\\% of D. cuprea had fragmented reproductive shoots built into their tube cap walls, with a highly significant regression of shoot to tube density (r2 = 0.76). There was a positive correlation between seedlings and tube caps (r2 = 0.39). D. cuprea may alter hydrodynamics, arresting transport of fragmented reproductive shoots, thereby potentially influencing patch and bed dynamics in both near and distant regions from existing beds. © 2001 Elsevier Science B.V.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Parmee, I. and Cvetkovic, D. and Bonham, C. and Packham, I.},\n\tyear = {2001},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n Diopatra cuprea (Bosc), a common tube-building polychaete, attaches materials such as algae and shell into the wall of its tube cap, in part, to provide a substrate for potential food resources. Reproductive shoots of eelgrass (Zostera marina L.) break off during seed maturation and can be transported by water movement. As these shoots deteriorate, they become neutrally or negatively buoyant and can be transported along the bottom while still carrying seeds. Analysis of 55 l m2 plots along a 100 m transect in the offshore fringe of an eelgrass bed in the York River, Chesapeake Bay, USA, showed that 70% of D. cuprea had fragmented reproductive shoots built into their tube cap walls, with a highly significant regression of shoot to tube density (r2 = 0.76). There was a positive correlation between seedlings and tube caps (r2 = 0.39). D. cuprea may alter hydrodynamics, arresting transport of fragmented reproductive shoots, thereby potentially influencing patch and bed dynamics in both near and distant regions from existing beds. © 2001 Elsevier Science B.V.\n
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\n \n\n \n \n \n \n \n The Identification, Conservation, and Management of Estuarine and Marine Nurseries for Fish and Invertebrates.\n \n \n \n\n\n \n BECK, M. W.; HECK, K. L.; ABLE, K. W.; CHILDERS, D. L.; EGGLESTON, D. B.; GILLANDERS, B. M.; HALPERN, B.; HAYS, C. G.; HOSHINO, K.; MINELLO, T. J.; ORTH, R. J.; SHERIDAN, P. F.; and WEINSTEIN, M. P.\n\n\n \n\n\n\n BioScience. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{beck_identification_2001,\n\ttitle = {The {Identification}, {Conservation}, and {Management} of {Estuarine} and {Marine} {Nurseries} for {Fish} and {Invertebrates}},\n\tdoi = {10.1641/0006-3568(2001)051[0633:ticamo]2.0.co;2},\n\tabstract = {A BETTER UNDERSTANDING OF THE HABITATS THAT SERVE AS NURSERIES FOR MARINE SPECIES AND THE FACTORS THAT CREATE SITE-SPECIFIC VARIABILITY IN NURSERY QUALITY WILL IMPROVE CONSERVATION AND MANAGEMENT OF THESE AREAS},\n\tjournal = {BioScience},\n\tauthor = {BECK, MICHAEL W. and HECK, KENNETH L. and ABLE, KENNETH W. and CHILDERS, DANIEL L. and EGGLESTON, DAVID B. and GILLANDERS, BRONWYN M. and HALPERN, BENJAMIN and HAYS, CYNTHIA G. and HOSHINO, KAHO and MINELLO, THOMAS J. and ORTH, ROBERT J. and SHERIDAN, PETER F. and WEINSTEIN, MICHAEL P.},\n\tyear = {2001},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n A BETTER UNDERSTANDING OF THE HABITATS THAT SERVE AS NURSERIES FOR MARINE SPECIES AND THE FACTORS THAT CREATE SITE-SPECIFIC VARIABILITY IN NURSERY QUALITY WILL IMPROVE CONSERVATION AND MANAGEMENT OF THESE AREAS\n
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\n \n\n \n \n \n \n \n Plant species diversity and composition: Experimental effects on marine epifaunal assemblages.\n \n \n \n\n\n \n Parker, J. D.; Duffy, J. E.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{parker_plant_2001,\n\ttitle = {Plant species diversity and composition: {Experimental} effects on marine epifaunal assemblages},\n\tdoi = {10.3354/meps224055},\n\tabstract = {Plant diversity is believed to govern animal community structure, yet few studies have tested this relationship. We manipulated plant species diversity and composition (2 seagrasses and 3 seaweeds) and measured the abundance, diversity, and biomass of plant-associated macroinvertebrates in a temperate, estuarine seagrass community. Animal diversity was weakly but positively related to plant diversity (Simpson's 1 - λ). Most indices of animal diversity, however, were more strongly related to total plant surface area than to plant diversity. Epifaunal abundance and biomass increased, whereas epifaunal diversity and evenness decreased with total plant surface area. Both food and habitat covary with plant surface area, providing potential mechanistic explanations for these patterns. Plant species composition had strong effects on epifaunal community structure. After statistically controlling for effects of plant surface area, epifaunal abundance and biomass remained higher, and evenness remained lower, among assemblages composed of branched (mostly seaweeds) relative to unbranched (mostly seagrasses) macrophytes. Multiple regression analyses also revealed differential use of particular plant species by epifauna. For example, amphipods responded particularly strongly to the coarsely branched red alga Gracilaria verrucosa. Thus, our experimental results support a strong effect of plant species composition, and little effect of plant diversity per se, on the motile macrofauna that we studied. This conclusion is consistent with results of a concurrent field survey; epifaunal community structure differed among plant species and seasons, with no host-plant specialists. These results support evidence from both terrestrial and aquatic communities; ecosystem structural and functional properties are often more strongly influenced by particular attributes, rather than number of species, in a community.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Parker, John D. and Duffy, J. Emmett and Orth, Robert J.},\n\tyear = {2001},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Plant diversity is believed to govern animal community structure, yet few studies have tested this relationship. We manipulated plant species diversity and composition (2 seagrasses and 3 seaweeds) and measured the abundance, diversity, and biomass of plant-associated macroinvertebrates in a temperate, estuarine seagrass community. Animal diversity was weakly but positively related to plant diversity (Simpson's 1 - λ). Most indices of animal diversity, however, were more strongly related to total plant surface area than to plant diversity. Epifaunal abundance and biomass increased, whereas epifaunal diversity and evenness decreased with total plant surface area. Both food and habitat covary with plant surface area, providing potential mechanistic explanations for these patterns. Plant species composition had strong effects on epifaunal community structure. After statistically controlling for effects of plant surface area, epifaunal abundance and biomass remained higher, and evenness remained lower, among assemblages composed of branched (mostly seaweeds) relative to unbranched (mostly seagrasses) macrophytes. Multiple regression analyses also revealed differential use of particular plant species by epifauna. For example, amphipods responded particularly strongly to the coarsely branched red alga Gracilaria verrucosa. Thus, our experimental results support a strong effect of plant species composition, and little effect of plant diversity per se, on the motile macrofauna that we studied. This conclusion is consistent with results of a concurrent field survey; epifaunal community structure differed among plant species and seasons, with no host-plant specialists. These results support evidence from both terrestrial and aquatic communities; ecosystem structural and functional properties are often more strongly influenced by particular attributes, rather than number of species, in a community.\n
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\n \n\n \n \n \n \n \n Seasonal variations in eelgrass (Zostera marina L.) responses to nutrient enrichment and reduced light availability in experimental ecosystems.\n \n \n \n\n\n \n Moore, K. A.; and Wetzel, R. L.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 2000.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{moore_seasonal_2000,\n\ttitle = {Seasonal variations in eelgrass ({Zostera} marina {L}.) responses to nutrient enrichment and reduced light availability in experimental ecosystems},\n\tdoi = {10.1016/S0022-0981(99)00135-5},\n\tabstract = {The single and interactive effects of altered water column nutrient concentrations and light availability on the growth of the seagrass Zostera marina L. (eelgrass) and its attached epiphytes were investigated in 110 liter microcosms. Experiments lasting 4 to 6 weeks were conducted seasonally during spring, summer and fall in a greenhouse equipped with flow-through seawater from the adjacent York River estuary of the Chesapeake Bay. Nutrient treatments consisted of inflow seawater with ambient or enriched (2 x to 3 x) concentrations of dissolved inorganic nitrogen and phosphorus and with rapid turnover (16 d-1). Enrichment levels were chosen to evaluate conditions found in regions of the Chesapeake Bay where Z. marina has declined. Light reductions were accomplished by shading individual microcosms with neutral density screening so that mean scalar irradiance was 42, 28, or 9\\% of solar PAR. These levels were chosen to simulate light reductions observed along gradients of turbidity which characterize present and former Z. marina habitats in the region. Epiphytic grazers consisted of gastropods (Bittium varium and Mittella lunata) which were applied at consistent densities (5200 m-2) for all experiments. Growth of both the seagrasses and their associated epiphytes decreased with increased shading. There was little additional response to nutrient enrichment except at highest light levels during the spring when macroepiphytes increased to over 10 x the seagrass mass and seagrass growth decreased. The results suggest that it is principally light availability which governs seagrass growth in moderately nutrient enriched regions of the bay. In systems such as the York River, given adequate grazer densities, observed levels of nutrient enrichment are unlikely to cause excessive epiphyte loads and subsequent seagrass declines. Although Z. marina tissue levels of nitrogen and phosphorus increased significantly with enrichment and with shading no direct effects of nitrate toxicity were observed.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Moore, Kenneth A. and Wetzel, Richard L.},\n\tyear = {2000},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The single and interactive effects of altered water column nutrient concentrations and light availability on the growth of the seagrass Zostera marina L. (eelgrass) and its attached epiphytes were investigated in 110 liter microcosms. Experiments lasting 4 to 6 weeks were conducted seasonally during spring, summer and fall in a greenhouse equipped with flow-through seawater from the adjacent York River estuary of the Chesapeake Bay. Nutrient treatments consisted of inflow seawater with ambient or enriched (2 x to 3 x) concentrations of dissolved inorganic nitrogen and phosphorus and with rapid turnover (16 d-1). Enrichment levels were chosen to evaluate conditions found in regions of the Chesapeake Bay where Z. marina has declined. Light reductions were accomplished by shading individual microcosms with neutral density screening so that mean scalar irradiance was 42, 28, or 9% of solar PAR. These levels were chosen to simulate light reductions observed along gradients of turbidity which characterize present and former Z. marina habitats in the region. Epiphytic grazers consisted of gastropods (Bittium varium and Mittella lunata) which were applied at consistent densities (5200 m-2) for all experiments. Growth of both the seagrasses and their associated epiphytes decreased with increased shading. There was little additional response to nutrient enrichment except at highest light levels during the spring when macroepiphytes increased to over 10 x the seagrass mass and seagrass growth decreased. The results suggest that it is principally light availability which governs seagrass growth in moderately nutrient enriched regions of the bay. In systems such as the York River, given adequate grazer densities, observed levels of nutrient enrichment are unlikely to cause excessive epiphyte loads and subsequent seagrass declines. Although Z. marina tissue levels of nitrogen and phosphorus increased significantly with enrichment and with shading no direct effects of nitrate toxicity were observed.\n
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\n \n\n \n \n \n \n \n Effects of a deposit-feeding invertebrate on the entrapment of Zostera marina L. seeds.\n \n \n \n\n\n \n Luckenbach, M. W.; and Orth, R. J.\n\n\n \n\n\n\n Aquatic Botany. 1999.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{luckenbach_effects_1999,\n\ttitle = {Effects of a deposit-feeding invertebrate on the entrapment of {Zostera} marina {L}. seeds},\n\tdoi = {10.1016/S0304-3770(98)00098-9},\n\tabstract = {Eelgrass, Zostera marina, relies upon seed dispersal for colonization of new habitats. The seeds are not readily transported in suspension; however, they have low erosion thresholds and are subject to horizontal transport as bedload at relatively low bottom shear stress. Field germination patterns suggest that seeds rarely travel far from the point of release and quickly become buried in the sediment, even in habitats where boundary-layer flows exceed those necessary to erode seeds. In many sedimentary habitats it is likely that the activities of benthic and demersal organisms will affect the horizontal movement and burial of seeds, thus providing an explanation for the patterns of seedling establishment in previously reported experiments. We investigated the effects of a common animal in estuarine sediments on the entrapment of Z. marina seeds. In a series of flume experiments we manipulated the densities of the subsurface deposit-feeding polychaete Clymenella torquata (Low: 96 worms m-2; Medium: 192 worms m-2; High: 288 worms m-2) and related trapping of seeds to worm density and bioturbation rates. The results suggest that modifications to the sediment surface (i.e. topographic relief) resulting from feeding and defecation activities of subsurface deposit feeders can act to trap seeds. Seeds were trapped in the medium and high density worm treatments in greater numbers than in the low density and no worm treatments. Our findings indicate that benthic invertebrates, through their modification of sediments may affect the horizontal (bedload) and, hence, vertical (burial) transport of Z. marina seeds.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Luckenbach, Mark W. and Orth, Robert J.},\n\tyear = {1999},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Eelgrass, Zostera marina, relies upon seed dispersal for colonization of new habitats. The seeds are not readily transported in suspension; however, they have low erosion thresholds and are subject to horizontal transport as bedload at relatively low bottom shear stress. Field germination patterns suggest that seeds rarely travel far from the point of release and quickly become buried in the sediment, even in habitats where boundary-layer flows exceed those necessary to erode seeds. In many sedimentary habitats it is likely that the activities of benthic and demersal organisms will affect the horizontal movement and burial of seeds, thus providing an explanation for the patterns of seedling establishment in previously reported experiments. We investigated the effects of a common animal in estuarine sediments on the entrapment of Z. marina seeds. In a series of flume experiments we manipulated the densities of the subsurface deposit-feeding polychaete Clymenella torquata (Low: 96 worms m-2; Medium: 192 worms m-2; High: 288 worms m-2) and related trapping of seeds to worm density and bioturbation rates. The results suggest that modifications to the sediment surface (i.e. topographic relief) resulting from feeding and defecation activities of subsurface deposit feeders can act to trap seeds. Seeds were trapped in the medium and high density worm treatments in greater numbers than in the low density and no worm treatments. Our findings indicate that benthic invertebrates, through their modification of sediments may affect the horizontal (bedload) and, hence, vertical (burial) transport of Z. marina seeds.\n
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\n \n\n \n \n \n \n \n Ontogenetic changes in habitat use by postlarvae and young juveniles of the blue crab.\n \n \n \n\n\n \n Pardieck, R. A.; Orth, R. J.; Diaz, R. J.; and Lipcius, R. N.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1999.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{pardieck_ontogenetic_1999,\n\ttitle = {Ontogenetic changes in habitat use by postlarvae and young juveniles of the blue crab},\n\tdoi = {10.3354/meps186227},\n\tabstract = {Changing habitat requirements are evident during the developmental cycles of many species. In this field investigation, we attempted to distinguish between depth (shallow vs deep), habitat structure (seagrass species), and study site as factors influencing the distribution and abundance of postlarvae and juvenile blue crabs Callinectes sapidus in the Chesapeake Bay. Deep (≥ 70 cm mean low water [MLW]) and shallow (≤ 50 cm MLW) suction samples in monospecific Zostera marina and Ruppia maritima beds were taken in the York River, a tributary of the Chesapeake Bay. Our studies revealed ontogenetic changes in habitat use, which suggested that blue crabs are influenced differently by physical and biological factors even during the earliest life stages. Postlarvae through 3rd instar distributions were not related to seagrass species, but their densities increased with distance upriver (regression, p {\\textbackslash}textless 0.004, n = 36 to 38 postlarvae: r2 = 0.173, 1st instars: r2 = 0.308, 2nd-3rd instar r2= 0.231). This suggests that the smallest instar distributions are related to larval supply and physical forces, such as currents and winds, which determine water-column transport. In contrast, 4th and greater instars were significantly more abundant in Ruppia than in Zostera (ANOVA, df = 1, p {\\textbackslash}textless 0.05), possibly because of the high shoot density of Ruppia beds. Habitat use by 4th and greater instars may be related to seasonal changes in seagrass shoot density. Water depth did not influence the distribution of any crab stage. We suggest that habitat selection and differential mortality among habitats influence larger instar distributions more strongly than they influence the distribution of postlarvae and the earliest instars of C. sapidus.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Pardieck, Renee A. and Orth, Robert J. and Diaz, Robert J. and Lipcius, Romuald N.},\n\tyear = {1999},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Changing habitat requirements are evident during the developmental cycles of many species. In this field investigation, we attempted to distinguish between depth (shallow vs deep), habitat structure (seagrass species), and study site as factors influencing the distribution and abundance of postlarvae and juvenile blue crabs Callinectes sapidus in the Chesapeake Bay. Deep (≥ 70 cm mean low water [MLW]) and shallow (≤ 50 cm MLW) suction samples in monospecific Zostera marina and Ruppia maritima beds were taken in the York River, a tributary of the Chesapeake Bay. Our studies revealed ontogenetic changes in habitat use, which suggested that blue crabs are influenced differently by physical and biological factors even during the earliest life stages. Postlarvae through 3rd instar distributions were not related to seagrass species, but their densities increased with distance upriver (regression, p \\textless 0.004, n = 36 to 38 postlarvae: r2 = 0.173, 1st instars: r2 = 0.308, 2nd-3rd instar r2= 0.231). This suggests that the smallest instar distributions are related to larval supply and physical forces, such as currents and winds, which determine water-column transport. In contrast, 4th and greater instars were significantly more abundant in Ruppia than in Zostera (ANOVA, df = 1, p \\textless 0.05), possibly because of the high shoot density of Ruppia beds. Habitat use by 4th and greater instars may be related to seasonal changes in seagrass shoot density. Water depth did not influence the distribution of any crab stage. We suggest that habitat selection and differential mortality among habitats influence larger instar distributions more strongly than they influence the distribution of postlarvae and the earliest instars of C. sapidus.\n
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\n \n\n \n \n \n \n \n Cannibal-prey dynamics in young juveniles and postlarvae of the blue crab.\n \n \n \n\n\n \n Moksnes, P. O.; Lipcius, R. N.; Pihl, L.; and Van Montfrans, J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1997.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{moksnes_cannibal-prey_1997,\n\ttitle = {Cannibal-prey dynamics in young juveniles and postlarvae of the blue crab},\n\tdoi = {10.1016/S0022-0981(97)00052-X},\n\tabstract = {Although cannibalism can act as a density-dependent regulator of population size in terrestrial systems, little is known of its effects in the marine environment. Herein we investigate the influence of cannibalism upon the early life history stages of the blue crab, Callinectes sapidus Rathbun, emphasizing cannibalism between juveniles and postlarvae (i.e. megalopae) of the same year class. In laboratory mesocosms we examined various factors modulating cannibal-prey dynamics, specifically: (1) the effects of habitat and presence of conspecifics on postlarval metamorphosis rate; (2) the effect of metamorphosis rate on the mortality of postlarvae from both intra- and inter-cohort cannibalism; (3) the effects of habitat and predator density on the functional response of young juvenile blue crab predators to varying densities of postlarval prey, and (4) the effects of prey size and habitat on predation mortality. Inter-cohort cannibalism caused significant mortality in every crab size and habitat type combination, and was lower in grass than sand for all prey smaller than fifth instar. Cannibalism between postlarvae was associated with metamorphosis and was density-dependent in sand, but not present in grass. Metamorphosis rates of postlarvae were inversely density- dependent in sand, but density-independent and higher in grass, indicating that habitat and intra-cohort agonism likely affects postlarval metamorphosis rates. Inter-cohort cannibalism was negatively correlated with metamorphosis rates of postlarvae. The functional response of young juvenile cannibalistic blue crabs differed significantly between sand and grass habitats, and between medium and high predator densities. Juvenile crabs displayed a type II, inversely density-dependent functional response in sand, resulting in very high mortality at low densities of postlarval prey. In grass, the crabs displayed a weak type III, density dependent response, yielding significantly lower mortality at low prey densities. Thus, habitat complexity changes the form of the functional response in cannibal-prey interactions and grass provides a relative habitat refuge from cannibalism. Doubling the number of predators in grass decreased the consumption rates per predator significantly and eliminated the density-dependence, indicating that intraspecific density can qualitatively change the form of the functional response. In the crab size experiment, only prey smaller than fifth instars received a habitat refuge from cannibalism in grass, whereas fifth instars received a relative size refuge in sand. Our results demonstrate that intra-year class cannibalism can cause mortality upon settling megalopae and first juvenile instars that is dependent on prey density. We expect inter-cohort cannibalism to cause local extinction of cohorts settling in sand, especially at low settlement densities, and high mortality at moderate settlement densities in grass. Satiation of predators at high settlement densities in grass suggests that episodic settlement can overwhelm predators locally. Furthermore, density-dependent mutual interference within large cohorts in the grass beds likely reduces their predation efficiency, indicating that aggregation of conspecific predators in grass habitats does not necessary lead to an increase in predation pressure. Finally, a relative size-refuge from inter- cohort cannibalism for fifth instar crabs supports an ontogenetic habitat shift around this crab size, which may be influenced by density-dependent agonistic behavior within cohorts. We suggest that intra-year class cannibalism is a major process regulating both survival and dispersal in megalopae and juvenile blue crabs.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Moksnes, P. O. and Lipcius, R. N. and Pihl, L. and Van Montfrans, J.},\n\tyear = {1997},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Although cannibalism can act as a density-dependent regulator of population size in terrestrial systems, little is known of its effects in the marine environment. Herein we investigate the influence of cannibalism upon the early life history stages of the blue crab, Callinectes sapidus Rathbun, emphasizing cannibalism between juveniles and postlarvae (i.e. megalopae) of the same year class. In laboratory mesocosms we examined various factors modulating cannibal-prey dynamics, specifically: (1) the effects of habitat and presence of conspecifics on postlarval metamorphosis rate; (2) the effect of metamorphosis rate on the mortality of postlarvae from both intra- and inter-cohort cannibalism; (3) the effects of habitat and predator density on the functional response of young juvenile blue crab predators to varying densities of postlarval prey, and (4) the effects of prey size and habitat on predation mortality. Inter-cohort cannibalism caused significant mortality in every crab size and habitat type combination, and was lower in grass than sand for all prey smaller than fifth instar. Cannibalism between postlarvae was associated with metamorphosis and was density-dependent in sand, but not present in grass. Metamorphosis rates of postlarvae were inversely density- dependent in sand, but density-independent and higher in grass, indicating that habitat and intra-cohort agonism likely affects postlarval metamorphosis rates. Inter-cohort cannibalism was negatively correlated with metamorphosis rates of postlarvae. The functional response of young juvenile cannibalistic blue crabs differed significantly between sand and grass habitats, and between medium and high predator densities. Juvenile crabs displayed a type II, inversely density-dependent functional response in sand, resulting in very high mortality at low densities of postlarval prey. In grass, the crabs displayed a weak type III, density dependent response, yielding significantly lower mortality at low prey densities. Thus, habitat complexity changes the form of the functional response in cannibal-prey interactions and grass provides a relative habitat refuge from cannibalism. Doubling the number of predators in grass decreased the consumption rates per predator significantly and eliminated the density-dependence, indicating that intraspecific density can qualitatively change the form of the functional response. In the crab size experiment, only prey smaller than fifth instars received a habitat refuge from cannibalism in grass, whereas fifth instars received a relative size refuge in sand. Our results demonstrate that intra-year class cannibalism can cause mortality upon settling megalopae and first juvenile instars that is dependent on prey density. We expect inter-cohort cannibalism to cause local extinction of cohorts settling in sand, especially at low settlement densities, and high mortality at moderate settlement densities in grass. Satiation of predators at high settlement densities in grass suggests that episodic settlement can overwhelm predators locally. Furthermore, density-dependent mutual interference within large cohorts in the grass beds likely reduces their predation efficiency, indicating that aggregation of conspecific predators in grass habitats does not necessary lead to an increase in predation pressure. Finally, a relative size-refuge from inter- cohort cannibalism for fifth instar crabs supports an ontogenetic habitat shift around this crab size, which may be influenced by density-dependent agonistic behavior within cohorts. We suggest that intra-year class cannibalism is a major process regulating both survival and dispersal in megalopae and juvenile blue crabs.\n
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\n \n\n \n \n \n \n \n Cannibalism, refugia and the molting blue crab.\n \n \n \n\n\n \n Ryer, C. H.; Van Montfrans, J.; and Moody, K. E.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1997.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ryer_cannibalism_1997,\n\ttitle = {Cannibalism, refugia and the molting blue crab},\n\tdoi = {10.3354/meps147077},\n\tabstract = {In this study, we examined how habitat and tidal stage influence predation upon molting blue crabs Callinectes sapidus. On 3 separate occasions we monitored the survival of tethered soft crabs in each of 2 different-sized marsh creeks and 2 seagrass sites, during both low and high tides. On one of these occasions, we also tethered hard crabs. Survival was much lower for soft crabs than for hard crabs, indicating that crabs may be particularly vulnerable when they molt. In both seagrass and marsh creeks, there was a tidal influence upon soft crab survival, with greater survival during low tides. There was no generalized difference in survival of soft crabs between habitats, i.e. marsh creek versus grassbed. Survival was high in the small marsh creek, but lower in the large marsh creek. In both creeks survival remained relatively constant throughout the summer. In contrast, survival did not differ between the 2 seagrass sites and was comparable to that in the small marsh creek early in the summer, but decreased to levels comparable to the large marsh creek by summers end. In the marsh creek, micro-habitat also influenced survival, with greater survival along the creek edge micro-habitats than in the creek centers. Cannibalism was the only identifiable source of mortality among tethered crabs. These results demonstrate that where and when a crab molts may greatly influence its chances for survival.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Ryer, Clifford H. and Van Montfrans, Jacques and Moody, Kurt E.},\n\tyear = {1997},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n In this study, we examined how habitat and tidal stage influence predation upon molting blue crabs Callinectes sapidus. On 3 separate occasions we monitored the survival of tethered soft crabs in each of 2 different-sized marsh creeks and 2 seagrass sites, during both low and high tides. On one of these occasions, we also tethered hard crabs. Survival was much lower for soft crabs than for hard crabs, indicating that crabs may be particularly vulnerable when they molt. In both seagrass and marsh creeks, there was a tidal influence upon soft crab survival, with greater survival during low tides. There was no generalized difference in survival of soft crabs between habitats, i.e. marsh creek versus grassbed. Survival was high in the small marsh creek, but lower in the large marsh creek. In both creeks survival remained relatively constant throughout the summer. In contrast, survival did not differ between the 2 seagrass sites and was comparable to that in the small marsh creek early in the summer, but decreased to levels comparable to the large marsh creek by summers end. In the marsh creek, micro-habitat also influenced survival, with greater survival along the creek edge micro-habitats than in the creek centers. Cannibalism was the only identifiable source of mortality among tethered crabs. These results demonstrate that where and when a crab molts may greatly influence its chances for survival.\n
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\n \n\n \n \n \n \n \n Nursery role of seagrass beds: Enhanced growth of juvenile blue crabs (Callinectes sapidus rathbun).\n \n \n \n\n\n \n Perkins-Visser, E.; Wolcott, T. G.; and Wolcott, D. L.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{perkins-visser_nursery_1996,\n\ttitle = {Nursery role of seagrass beds: {Enhanced} growth of juvenile blue crabs ({Callinectes} sapidus rathbun)},\n\tdoi = {10.1016/0022-0981(96)00014-7},\n\tabstract = {The role of submerged aquatic vegetation in supporting enhanced growth of Callinectes sapidus was investigated through field and laboratory experiments. In predator-free enclosures (l m2) in the lower York River, Virginia, juvenile blue crabs within Zostera marina (L.) beds grew taster than crabs in enclosures deployed outside the beds. First stage crabs were introduced into vegetated or unvegetated enclosures at either 10 or 50 crabs m-2. After the 6 wk experimental period, both survival and growth were significantly higher in vegetated treatments (growth was estimated by change in 'volume,' the product of carapace width, length and depth). In fiberglass mesocosms (2.67 m x 1.33 m x 0.67 m) divided into vegetated and unvegetated halves, juvenile blue crabs grew faster in the vegetation, consistent with field findings. Where differences existed between density treatments in field enclosures, juvenile crabs grew faster in high density than in low density treatments. Aggregate crab growth (summed 'volumes' of all recaptured individuals) for vegetated enclosures was greater than for unvegetated enclosures. Potential contribution of cannibalism was sufficient to explain some within-habitat density effects, but was not sufficient to account for the entire aggregate differences, suggesting that food may not be limiting within the seagrass beds even at 50 crabs m-2. These results show that early stage blue crabs receive a substantial growth advantage, in addition to the refuge function shown in other studies, from their association with seagrass beds. This trophic advantage may be experienced by juveniles of other species that utilize vegetated nursery areas and may help explain the oncogenetic habitat shifts that characterize many life histories.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Perkins-Visser, Eileen and Wolcott, Thomas G. and Wolcott, Donna L.},\n\tyear = {1996},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The role of submerged aquatic vegetation in supporting enhanced growth of Callinectes sapidus was investigated through field and laboratory experiments. In predator-free enclosures (l m2) in the lower York River, Virginia, juvenile blue crabs within Zostera marina (L.) beds grew taster than crabs in enclosures deployed outside the beds. First stage crabs were introduced into vegetated or unvegetated enclosures at either 10 or 50 crabs m-2. After the 6 wk experimental period, both survival and growth were significantly higher in vegetated treatments (growth was estimated by change in 'volume,' the product of carapace width, length and depth). In fiberglass mesocosms (2.67 m x 1.33 m x 0.67 m) divided into vegetated and unvegetated halves, juvenile blue crabs grew faster in the vegetation, consistent with field findings. Where differences existed between density treatments in field enclosures, juvenile crabs grew faster in high density than in low density treatments. Aggregate crab growth (summed 'volumes' of all recaptured individuals) for vegetated enclosures was greater than for unvegetated enclosures. Potential contribution of cannibalism was sufficient to explain some within-habitat density effects, but was not sufficient to account for the entire aggregate differences, suggesting that food may not be limiting within the seagrass beds even at 50 crabs m-2. These results show that early stage blue crabs receive a substantial growth advantage, in addition to the refuge function shown in other studies, from their association with seagrass beds. This trophic advantage may be experienced by juveniles of other species that utilize vegetated nursery areas and may help explain the oncogenetic habitat shifts that characterize many life histories.\n
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\n \n\n \n \n \n \n \n Review of factors affecting the distribution and abundance of waterfowl in shallow-water habitats of chesapeake bay.\n \n \n \n\n\n \n Perry, M. C.; and Deller, A. S.\n\n\n \n\n\n\n In Estuaries, 1996. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@inproceedings{perry_review_1996,\n\ttitle = {Review of factors affecting the distribution and abundance of waterfowl in shallow-water habitats of chesapeake bay},\n\tdoi = {10.2307/1352232},\n\tabstract = {Long-term trends of waterfowl populations in Chesapeake Bay demonstrate the importance of shallow-water habitats for waterfowl species. Although recent increases in field feeding by geese and swans lessened the importance of shallow-water areas for these species, most duck species depend almost exclusively on shallow-water habitats. Many factors influenced the distribution and abundance of waterfowl in shallow-water habitats. Habitat degradation resulted in the decline in numbers of most duck species and a change in distribution of some species. Increased numbers of mallards (Anas platyrhynchos) in recent decades probably resulted from release programs conducted by the Maryland Department of Natural Resources and private individuals. Studies of food habits since 1885 showed a decline in submerged-aquatic vegetation in the diet of some species, such as the canvasback (Aythya valisineria), and an increase in the proportions of invertebrates in the diet. Diversity of food organisms for many waterfowl species has declined. Surveys of vegetation and invertebrates in the Chesapeake Bay generally reflect a degradation of shallow-water habitat. Human population increases in the Chesapeake Bay watershed directly and indirectly affected waterfowl distribution and abundance. The increase of exotic plant and invertebrate species in the bay, in most cases, benefited waterfowl populations. Increased contaminants have reduced the quality and quantity of habitat, although serious attempts to reverse this trend are underway. The use of shallow-water habitats by humans for fishing, hunting, boating, and other recreational and commercial uses reduced the use of shallow-water habitats by waterfowl. Humans can lessen the adverse influences on the valuable shallow-water habitats by restricting human population growth near these habitats and improving the water quality of the bay tributaries. Other affirmative actions that will improve these areas for waterfowl include greater restrictions on boat traffic in shallow-water habitats and establishing more sanctuaries in shallow-water areas that have complete protection from human disturbance.},\n\tbooktitle = {Estuaries},\n\tauthor = {Perry, Matthew C. and Deller, Amy S.},\n\tyear = {1996},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n\n\n
\n Long-term trends of waterfowl populations in Chesapeake Bay demonstrate the importance of shallow-water habitats for waterfowl species. Although recent increases in field feeding by geese and swans lessened the importance of shallow-water areas for these species, most duck species depend almost exclusively on shallow-water habitats. Many factors influenced the distribution and abundance of waterfowl in shallow-water habitats. Habitat degradation resulted in the decline in numbers of most duck species and a change in distribution of some species. Increased numbers of mallards (Anas platyrhynchos) in recent decades probably resulted from release programs conducted by the Maryland Department of Natural Resources and private individuals. Studies of food habits since 1885 showed a decline in submerged-aquatic vegetation in the diet of some species, such as the canvasback (Aythya valisineria), and an increase in the proportions of invertebrates in the diet. Diversity of food organisms for many waterfowl species has declined. Surveys of vegetation and invertebrates in the Chesapeake Bay generally reflect a degradation of shallow-water habitat. Human population increases in the Chesapeake Bay watershed directly and indirectly affected waterfowl distribution and abundance. The increase of exotic plant and invertebrate species in the bay, in most cases, benefited waterfowl populations. Increased contaminants have reduced the quality and quantity of habitat, although serious attempts to reverse this trend are underway. The use of shallow-water habitats by humans for fishing, hunting, boating, and other recreational and commercial uses reduced the use of shallow-water habitats by waterfowl. Humans can lessen the adverse influences on the valuable shallow-water habitats by restricting human population growth near these habitats and improving the water quality of the bay tributaries. Other affirmative actions that will improve these areas for waterfowl include greater restrictions on boat traffic in shallow-water habitats and establishing more sanctuaries in shallow-water areas that have complete protection from human disturbance.\n
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\n \n\n \n \n \n \n \n Density-dependent settler-recruit-juvenile relationships in blue crabs.\n \n \n \n\n\n \n Pile, A. J.; Lipcius, R. N.; Van Montfrans, J.; and Orth, R. J.\n\n\n \n\n\n\n Ecological Monographs. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{pile_density-dependent_1996,\n\ttitle = {Density-dependent settler-recruit-juvenile relationships in blue crabs},\n\tdoi = {10.2307/2963519},\n\tabstract = {Current theory on the population dynamics of marine species with complex life history patterns posits that a suite of physical and biotic forces (e.g., habitat structure and density-dependent predation or emigration) control survival and abundance in early life history, particularly after settlement. We have conducted a long-term sampling effort accompanied by a series of field and laboratory experiments examining the joint effects of habitat type, body size, and population density upon abundance and survival of early juveniles of the blue crab, Callinectes sapidus. In addition, the chance occurrence of a tropical storm during one set of experiments provided an opportunity to assess the impact of a physical disturbance upon newly settled blue crab survival and abundance. In the 10-yr sampling effort, we quantified relationships between sequential life history stages (juvenile crab instars) in seagrass beds, the initial nursery habitat for blue crabs in the lower Chesapeake Bay. Inter-instar relationships were defined as the densities of larger instars as dependent on the densities of smaller instars. Inter-instar relationships for the youngest instars are described by hyperbolic functions until crabs begin to emigrate to unvegetated habitats at approximately the fifth instar. Inter-instar relationships between crabs larger than the fifth instar and smaller crabs become either parabolic or linear functions and decay as the number of instars between sequential life history stages increases. While both the hyperbolic and parabolic functions are indicative of populations regulated by density-dependent processes, either predation or emigration, the decay in the functions describing the inter-instar relationships for crabs larger than the fifth instar indicates that the suite of processes regulating this segment of the population changes qualitatively. In laboratory and field experiments, the effects of vegetated and unvegetated habitats and size-specific predation on newly settled juveniles were tested. Tethering was used to quantify relative rates of predation, and a laboratory study was conducted to determine if tethering induced treatment-specific bias. We found no statistically significant interactions between the tethering treatment and the factor treatments of crab size and habitat during the laboratory study, indicating that tethering did not produce treatment-specific bias. Thus, tethering provided a relative measure of predation that allowed comparisons between treatments of habitat and crab size on crab survival. In both laboratory and field experiments, survival was significantly higher in vegetated habitats and with increasing size until the ninth instar, when survival did not differ by habitat. This difference explains the dispersal from vegetated to unvegetated habitats that occurred between the fifth and seventh instars. In addition, survival of all crabs was significantly increased both during and after Tropical Storm Danielle compared to pre-storm conditions. A model is developed that describes juvenile survival as a function of crab size and habitat type. Survival curves in both habitats are represented by similar sigmoid functions with survival higher in vegetated habitats. Subsequently, the survival of newly settled blue crabs is likely dependent on the availability of complex habitat. Thus, a suite of biotic and physical processes, both density-dependent and density-independent, control the early life history after settlement for the blue crab.},\n\tjournal = {Ecological Monographs},\n\tauthor = {Pile, Adele J. and Lipcius, Romuald N. and Van Montfrans, Jacques and Orth, Robert J.},\n\tyear = {1996},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Current theory on the population dynamics of marine species with complex life history patterns posits that a suite of physical and biotic forces (e.g., habitat structure and density-dependent predation or emigration) control survival and abundance in early life history, particularly after settlement. We have conducted a long-term sampling effort accompanied by a series of field and laboratory experiments examining the joint effects of habitat type, body size, and population density upon abundance and survival of early juveniles of the blue crab, Callinectes sapidus. In addition, the chance occurrence of a tropical storm during one set of experiments provided an opportunity to assess the impact of a physical disturbance upon newly settled blue crab survival and abundance. In the 10-yr sampling effort, we quantified relationships between sequential life history stages (juvenile crab instars) in seagrass beds, the initial nursery habitat for blue crabs in the lower Chesapeake Bay. Inter-instar relationships were defined as the densities of larger instars as dependent on the densities of smaller instars. Inter-instar relationships for the youngest instars are described by hyperbolic functions until crabs begin to emigrate to unvegetated habitats at approximately the fifth instar. Inter-instar relationships between crabs larger than the fifth instar and smaller crabs become either parabolic or linear functions and decay as the number of instars between sequential life history stages increases. While both the hyperbolic and parabolic functions are indicative of populations regulated by density-dependent processes, either predation or emigration, the decay in the functions describing the inter-instar relationships for crabs larger than the fifth instar indicates that the suite of processes regulating this segment of the population changes qualitatively. In laboratory and field experiments, the effects of vegetated and unvegetated habitats and size-specific predation on newly settled juveniles were tested. Tethering was used to quantify relative rates of predation, and a laboratory study was conducted to determine if tethering induced treatment-specific bias. We found no statistically significant interactions between the tethering treatment and the factor treatments of crab size and habitat during the laboratory study, indicating that tethering did not produce treatment-specific bias. Thus, tethering provided a relative measure of predation that allowed comparisons between treatments of habitat and crab size on crab survival. In both laboratory and field experiments, survival was significantly higher in vegetated habitats and with increasing size until the ninth instar, when survival did not differ by habitat. This difference explains the dispersal from vegetated to unvegetated habitats that occurred between the fifth and seventh instars. In addition, survival of all crabs was significantly increased both during and after Tropical Storm Danielle compared to pre-storm conditions. A model is developed that describes juvenile survival as a function of crab size and habitat type. Survival curves in both habitats are represented by similar sigmoid functions with survival higher in vegetated habitats. Subsequently, the survival of newly settled blue crabs is likely dependent on the availability of complex habitat. Thus, a suite of biotic and physical processes, both density-dependent and density-independent, control the early life history after settlement for the blue crab.\n
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\n \n\n \n \n \n \n \n Utilization of seagrass habitat by the blue crab, Callinectes sapidus Rathbun, in Chesapeake Bay: a review.\n \n \n \n\n\n \n Orth, R J; Van Montfrans, J; Lipcius, R N; Metcalf, K S; Phillips, R C; Walker, D I; and Kirman, H\n\n\n \n\n\n\n 1996.\n Publication Title: Proceedings of an International Workshop on Seagrass biology\n\n\n\n
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@book{orth_utilization_1996,\n\ttitle = {Utilization of seagrass habitat by the blue crab, {Callinectes} sapidus {Rathbun}, in {Chesapeake} {Bay}: a review},\n\tabstract = {Seagrasses are generally presumed to provide important habitats for numerous species of vertebrates and invertebrates, serving as a nursery, structure for attachment, or foraging area. However, few species appear directly dependent on seagrass, one notable exception being the bay scallop, Argopecten irradians Lamarck. Research in Chesapeake Bay on the abundant, and commercially exploitable blue crab, Callinectes sapidus Rathbun, over the last decade, focused on the relevance of seagrass habitat for the overall population. Our research has demonstrated: 1. higher densities of juvenile blue crabs in seagrass habitats compared to adjacent marsh and unvegetated areas, 2. seagrasses to be an important settlement habitat for recruiting post-larval blue crabs, and 3. mediated predator-prey interactions related to seagrass abundance and increasing crab size. Our current research focuses on the importance of restored areas for blue crab survival and relevance of seagrass habitat bay wide in the context of landscape distributional patterns and metapopulation dynamics. Our findings suggest that similar habitats may differentially affect the numerical abundance of juvenile blue crabs. Elucidating the mechanistic reasons for the value of seagrass habitat for blue crabs, one of the last remaining, viable commercial fisheries in Chesapeake Bay, will be crucial in developing strategies for protecting and restoring seagrass habitat in Chesapeake Bay.},\n\tauthor = {Orth, R J and Van Montfrans, J and Lipcius, R N and Metcalf, K S and Phillips, R C and Walker, D I and Kirman, H},\n\tyear = {1996},\n\tnote = {Publication Title: Proceedings of an International Workshop on Seagrass biology},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n Seagrasses are generally presumed to provide important habitats for numerous species of vertebrates and invertebrates, serving as a nursery, structure for attachment, or foraging area. However, few species appear directly dependent on seagrass, one notable exception being the bay scallop, Argopecten irradians Lamarck. Research in Chesapeake Bay on the abundant, and commercially exploitable blue crab, Callinectes sapidus Rathbun, over the last decade, focused on the relevance of seagrass habitat for the overall population. Our research has demonstrated: 1. higher densities of juvenile blue crabs in seagrass habitats compared to adjacent marsh and unvegetated areas, 2. seagrasses to be an important settlement habitat for recruiting post-larval blue crabs, and 3. mediated predator-prey interactions related to seagrass abundance and increasing crab size. Our current research focuses on the importance of restored areas for blue crab survival and relevance of seagrass habitat bay wide in the context of landscape distributional patterns and metapopulation dynamics. Our findings suggest that similar habitats may differentially affect the numerical abundance of juvenile blue crabs. Elucidating the mechanistic reasons for the value of seagrass habitat for blue crabs, one of the last remaining, viable commercial fisheries in Chesapeake Bay, will be crucial in developing strategies for protecting and restoring seagrass habitat in Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Effects of predation on Zostera marina L. seed abundance.\n \n \n \n\n\n \n Fishman, J. R.; and Orth, R. J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{fishman_effects_1996,\n\ttitle = {Effects of predation on {Zostera} marina {L}. seed abundance},\n\tdoi = {10.1016/0022-0981(95)00176-X},\n\tabstract = {Predator effects on Zostera marina L. seed abundance were studied in the York River, VA, USA, using enclosure and exclosure caging experiments. Seeds were placed in cages in two concurrent experiments. The first experiment was a predator exclosure experiment to test the effects of excluding predators, using a full predator exclosure cage, a partial exclosure top-only cage, a partial exclosure side only cage and uncaged plots. The second experiment was a predator enclosure experiment, using two highly abundant macro-benthic predators in the Chesapeake Bay: the decapod crustacean Callinectes sapidus Rathbun and the sciaenid fish Micropogonias undulatus L. Additionally, two-week long trials of sequentially protected and exposed seeds were also performed. Replicate treatment plots were sampled by removing the top 5-10 cm of the sediment surface with a suction sampler and still viable seeds in each plot were counted. Full exclosure cages contained significantly higher numbers of seeds than the uncaged or partial caged treatments. Seed abundances in the C. sapidus enclosure cages were significantly less than the full exclusion cage, but not significantly different than the uncaged treatments. Seed abundances in the M. undulatus cages were not significantly different than the full exclusion cage. The least number of seeds were found in the uncaged and partial cage treatments. Results of the sequentially protected and exposed trials were similar to results from the one-week uncaged treatments. These experiments suggest that seed predation can affect the abundance of Z. marina seeds, possibly causing up to 65\\% of the seed losses observed in these experiments. Results suggest that seed predation has the potential to be an important force governing the sexual reproductive success and propagation of eelgrass beds and that the degree of seed loss via predation may be related to predator and primary food abundances.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Fishman, James R. and Orth, Robert J.},\n\tyear = {1996},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Predator effects on Zostera marina L. seed abundance were studied in the York River, VA, USA, using enclosure and exclosure caging experiments. Seeds were placed in cages in two concurrent experiments. The first experiment was a predator exclosure experiment to test the effects of excluding predators, using a full predator exclosure cage, a partial exclosure top-only cage, a partial exclosure side only cage and uncaged plots. The second experiment was a predator enclosure experiment, using two highly abundant macro-benthic predators in the Chesapeake Bay: the decapod crustacean Callinectes sapidus Rathbun and the sciaenid fish Micropogonias undulatus L. Additionally, two-week long trials of sequentially protected and exposed seeds were also performed. Replicate treatment plots were sampled by removing the top 5-10 cm of the sediment surface with a suction sampler and still viable seeds in each plot were counted. Full exclosure cages contained significantly higher numbers of seeds than the uncaged or partial caged treatments. Seed abundances in the C. sapidus enclosure cages were significantly less than the full exclusion cage, but not significantly different than the uncaged treatments. Seed abundances in the M. undulatus cages were not significantly different than the full exclusion cage. The least number of seeds were found in the uncaged and partial cage treatments. Results of the sequentially protected and exposed trials were similar to results from the one-week uncaged treatments. These experiments suggest that seed predation can affect the abundance of Z. marina seeds, possibly causing up to 65% of the seed losses observed in these experiments. Results suggest that seed predation has the potential to be an important force governing the sexual reproductive success and propagation of eelgrass beds and that the degree of seed loss via predation may be related to predator and primary food abundances.\n
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\n \n\n \n \n \n \n \n Setilement of blue crab postlarvae in Western North Atlantic Estuaries.\n \n \n \n\n\n \n van Montfrans, J.; Epifanio, C.; Knott, D.; Lipcius, R.; Mense, D.; Metcalf, K.; Olmi III, E.; Orth, R.; Posey, M.; and Wenner, E.\n\n\n \n\n\n\n Bulletin of Marine Science. 1995.\n \n\n\n\n
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@article{van_montfrans_setilement_1995,\n\ttitle = {Setilement of blue crab postlarvae in {Western} {North} {Atlantic} {Estuaries}},\n\tabstract = {We quantified variability in daily settlement of blue crab postlarvae (megalopae) on identical artificial settlement substrates at up to 6 sites concurrently over a broad geographic expanse ( similar to 1300 km) of the western North Atlantic (Delaware-South Carolina, USA). The 4-year study encompassed the blue crab recruitment season (generally July-November) from 1989-1992. Regional settlement was characterized by: (1) constant low levels of daily settlement punctuated by significantly non-random, episodic peaks of variable duration and intensity with peaks collectively accounting for at least half the total annual settlement at a site; (2) spatial and temporal variability leading to a general lack of coherence between sites in a given year and across years within a site; (3) occasional coherence in patterns between sites during a given year, suggesting linkages in regional processes affecting settlement; and, (4) significant semilunar patterns of episodic settlement pulses at the York River and Charleston Harbor sites over a 4-year period. Thus, regional settlement patterns exhibit both consistent (i.e., semilunar periodicity, episodic pulses) and variable (i.e., temporal and spatial variation) elements, which are likely due to a combination of stochastic and deterministic processes. Such patterns may impart an ecological advantage to crabs settling en masse (i.e., reduced encounter rate with predators through predator swamping) or at continuous low levels (i.e., below a density-dependent threshold) during the recruitment season. An identical study illustrated that settlement in Gulf of Mexico estuaries exhibited similarly episodic and highly variable patterns. Daily mean and total annual settlement were up to a hundred-fold greater for gulf than Atlantic Coast estuaries implying population limitation by post-settlement processes in the gulf and greater recruitment limitation in the Atlantic. These studies emphasize the merit of conducting research over a broad geographic range using standardized techniques to attempt meaningful ecological comparisons.},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {van Montfrans, Jacques and Epifanio, Charles and Knott, David and Lipcius, Romuald and Mense, David and Metcalf, Karen and Olmi III, Eugene and Orth, Robert and Posey, Martin and Wenner, Elizabeth},\n\tyear = {1995},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n We quantified variability in daily settlement of blue crab postlarvae (megalopae) on identical artificial settlement substrates at up to 6 sites concurrently over a broad geographic expanse ( similar to 1300 km) of the western North Atlantic (Delaware-South Carolina, USA). The 4-year study encompassed the blue crab recruitment season (generally July-November) from 1989-1992. Regional settlement was characterized by: (1) constant low levels of daily settlement punctuated by significantly non-random, episodic peaks of variable duration and intensity with peaks collectively accounting for at least half the total annual settlement at a site; (2) spatial and temporal variability leading to a general lack of coherence between sites in a given year and across years within a site; (3) occasional coherence in patterns between sites during a given year, suggesting linkages in regional processes affecting settlement; and, (4) significant semilunar patterns of episodic settlement pulses at the York River and Charleston Harbor sites over a 4-year period. Thus, regional settlement patterns exhibit both consistent (i.e., semilunar periodicity, episodic pulses) and variable (i.e., temporal and spatial variation) elements, which are likely due to a combination of stochastic and deterministic processes. Such patterns may impart an ecological advantage to crabs settling en masse (i.e., reduced encounter rate with predators through predator swamping) or at continuous low levels (i.e., below a density-dependent threshold) during the recruitment season. An identical study illustrated that settlement in Gulf of Mexico estuaries exhibited similarly episodic and highly variable patterns. Daily mean and total annual settlement were up to a hundred-fold greater for gulf than Atlantic Coast estuaries implying population limitation by post-settlement processes in the gulf and greater recruitment limitation in the Atlantic. These studies emphasize the merit of conducting research over a broad geographic range using standardized techniques to attempt meaningful ecological comparisons.\n
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\n \n\n \n \n \n \n \n Trophic ecology of two congeneric pipefishes (Syngnathidae) of the lower York River, Virginia.\n \n \n \n\n\n \n Teixeira, R. L.; and Musick, J. A.\n\n\n \n\n\n\n Environmental Biology of Fishes. 1995.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{teixeira_trophic_1995,\n\ttitle = {Trophic ecology of two congeneric pipefishes ({Syngnathidae}) of the lower {York} {River}, {Virginia}},\n\tdoi = {10.1007/BF00005862},\n\tabstract = {The northern pipefish, Syngnathus fuscus, and the dusky pipefish, S. floridae, co-exist in eelgrass beds in the lower York River. To compare the trophic ecology of both pipefishes, gut contents of 3488 northern pipefish, and 1422 dusky pipefish were examined and quantified by dry weight. Samples were taken with a dip net from May through November 1992. Syngnathus fuscus fed mainly on amphipods (Gammarus mucronatus, Amphithoe longimana, and Caprella penantis), and to a lesser degree on copepods, and isopods (Edotea spp. and Erichsonella attenuata). Syngnathus floridae fed mainly on grass shrimps (Palaemonetes pugio, P. vulgaris, and Palaemonetes eggs), and to a lesser degree on copepods, isopods, and mysids (Mysidopsis bigelowi). No seasonal trends were observed in the feeding habits of these pipefishes. Specimens of both species smaller than 100 mm TL fed mainly on copepods. Larger S. fuscus fed on amphipods, while larger S. floridae fed on grass shrimps. Schoener's diet overlap index revealed high consumption of the same prey type by both pipefish species only in July, but only for those specimens smaller than 110 mm TL. Food partitioning between both pipefish was associated with different snout sizes and shapes. © 1995 Kluwer Academic Publishers.},\n\tjournal = {Environmental Biology of Fishes},\n\tauthor = {Teixeira, Rogério L. and Musick, John A.},\n\tyear = {1995},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The northern pipefish, Syngnathus fuscus, and the dusky pipefish, S. floridae, co-exist in eelgrass beds in the lower York River. To compare the trophic ecology of both pipefishes, gut contents of 3488 northern pipefish, and 1422 dusky pipefish were examined and quantified by dry weight. Samples were taken with a dip net from May through November 1992. Syngnathus fuscus fed mainly on amphipods (Gammarus mucronatus, Amphithoe longimana, and Caprella penantis), and to a lesser degree on copepods, and isopods (Edotea spp. and Erichsonella attenuata). Syngnathus floridae fed mainly on grass shrimps (Palaemonetes pugio, P. vulgaris, and Palaemonetes eggs), and to a lesser degree on copepods, isopods, and mysids (Mysidopsis bigelowi). No seasonal trends were observed in the feeding habits of these pipefishes. Specimens of both species smaller than 100 mm TL fed mainly on copepods. Larger S. fuscus fed on amphipods, while larger S. floridae fed on grass shrimps. Schoener's diet overlap index revealed high consumption of the same prey type by both pipefish species only in July, but only for those specimens smaller than 110 mm TL. Food partitioning between both pipefish was associated with different snout sizes and shapes. © 1995 Kluwer Academic Publishers.\n
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\n \n\n \n \n \n \n \n Settlement indices for blue crab megalopae in the York River, Virginia: temporal relationships and statistical efficiency.\n \n \n \n\n\n \n Metcalf, K. S.; van Montfrans, J.; Lipcius, R. N.; and Orth, R. J.\n\n\n \n\n\n\n Bulletin of Marine Science. 1995.\n ISBN: 9788578110796 _eprint: arXiv:1011.1669v3\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{metcalf_settlement_1995,\n\ttitle = {Settlement indices for blue crab megalopae in the {York} {River}, {Virginia}: temporal relationships and statistical efficiency},\n\tdoi = {10.1017/CBO9781107415324.004},\n\tabstract = {The efficacy of artificial settlement substrates in quantifying relative rates of settlement of blue crab, Callinectes sapidus, postlarvae (megalopae) was examined. The technique has been widely used to assess settlement at local (Chesapeake Bay) and broad geographic scales (Atlantic and Gulf Coasts). This analysis examined differences in settlement between two configurations of substrates and two depths of deployment, in relation to lunar day, month, year and hours of flood tide occurring at night. Substrates were deployed daily for four years (1989-1992) during the settlement season (July-November) in the York River, Virginia. Set- tlement did not differ between substrate configurations (flat and cylindrical) deployed at the same location in the water column. Substrates deployed at the bottom of the water column had higher settlement than substrates at the surface, except during the last lunar month sam- pled (approximately November), when settlement was higher at the surface. There was a semilunar periodicity in settlement with high settlement following the new and full moon phases. Settlement varied annually and with lunar month. Statistical efficiency was achieved with a minimum of three or four replicate substrates. Cylindrical artificial settlement sub- strates are efficient, reliable and capable of detecting temporal patterns in settlement.},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {Metcalf, Karen S. and van Montfrans, Jacques and Lipcius, Romuald N. and Orth, Robert J.},\n\tyear = {1995},\n\tpmid = {25246403},\n\tnote = {ISBN: 9788578110796\n\\_eprint: arXiv:1011.1669v3},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The efficacy of artificial settlement substrates in quantifying relative rates of settlement of blue crab, Callinectes sapidus, postlarvae (megalopae) was examined. The technique has been widely used to assess settlement at local (Chesapeake Bay) and broad geographic scales (Atlantic and Gulf Coasts). This analysis examined differences in settlement between two configurations of substrates and two depths of deployment, in relation to lunar day, month, year and hours of flood tide occurring at night. Substrates were deployed daily for four years (1989-1992) during the settlement season (July-November) in the York River, Virginia. Set- tlement did not differ between substrate configurations (flat and cylindrical) deployed at the same location in the water column. Substrates deployed at the bottom of the water column had higher settlement than substrates at the surface, except during the last lunar month sam- pled (approximately November), when settlement was higher at the surface. There was a semilunar periodicity in settlement with high settlement following the new and full moon phases. Settlement varied annually and with lunar month. Statistical efficiency was achieved with a minimum of three or four replicate substrates. Cylindrical artificial settlement sub- strates are efficient, reliable and capable of detecting temporal patterns in settlement.\n
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\n \n\n \n \n \n \n \n Dynamics of epiphytic photoautotrophs and heterotrophs in Zostera marina (eelgrass) microcosms: Responses to nutrient enrichment and grazing.\n \n \n \n\n\n \n Neckles, H. A.; Koepfler, E. T.; Haas, L. W.; Wetzel, R. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{neckles_dynamics_1994,\n\ttitle = {Dynamics of epiphytic photoautotrophs and heterotrophs in {Zostera} marina (eelgrass) microcosms: {Responses} to nutrient enrichment and grazing},\n\tdoi = {10.2307/1352407},\n\tabstract = {The combined effects of nutrient enrichment and grazing by isopods and amphipods on abundances of seagrass epiphytes were tested in Zostera marina L. (eelgrass) microcosms. Using epifluorescence microscopy, densities of epiphytic diatoms, cyanobacteria, heterotrophic flagellates, and heterotrophic bacteria were enumerated after 1 mo and 2 mo of treatment. In general, numbers of diatoms decreased, in the presence of grazers and showed little response to nutrient enrichment, whereas numbers of cyanobacteria increased with nutrient enrichment and showed little response to grazing. Thus, macrofaunal grazing maintained a photoautotrophic community domainated by cyanobacteria, particularly under nutrient enriched conditions. Following 2 mo of treatment, dense macroalgal growth under nutrient-enriched conditins with grazers absent appeared to limit populations of both epiphytic autotrophs. Patterns of abundance of heterotrophic bacteria suggested that the original bacteria population was nutrient limited. Bacteria populations may have been limited by organic carbon supplies at the end of the experiment. Abundances of heterotrophic flagellates and bacteria were strongly correlated on both sampling dates. Results suggest that heterotrophic flagellates might serve as a link between heterotrophic bacterial production and higher trophic levels in seagrass epiphyte food webs. © 1994 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Neckles, Hilary A. and Koepfler, Eric T. and Haas, Leonard W. and Wetzel, Richard L. and Orth, Robert J.},\n\tyear = {1994},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The combined effects of nutrient enrichment and grazing by isopods and amphipods on abundances of seagrass epiphytes were tested in Zostera marina L. (eelgrass) microcosms. Using epifluorescence microscopy, densities of epiphytic diatoms, cyanobacteria, heterotrophic flagellates, and heterotrophic bacteria were enumerated after 1 mo and 2 mo of treatment. In general, numbers of diatoms decreased, in the presence of grazers and showed little response to nutrient enrichment, whereas numbers of cyanobacteria increased with nutrient enrichment and showed little response to grazing. Thus, macrofaunal grazing maintained a photoautotrophic community domainated by cyanobacteria, particularly under nutrient enriched conditions. Following 2 mo of treatment, dense macroalgal growth under nutrient-enriched conditins with grazers absent appeared to limit populations of both epiphytic autotrophs. Patterns of abundance of heterotrophic bacteria suggested that the original bacteria population was nutrient limited. Bacteria populations may have been limited by organic carbon supplies at the end of the experiment. Abundances of heterotrophic flagellates and bacteria were strongly correlated on both sampling dates. Results suggest that heterotrophic flagellates might serve as a link between heterotrophic bacterial production and higher trophic levels in seagrass epiphyte food webs. © 1994 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n The asiatic clam (Corbicula fluminea) invasion and system-level ecological change in the Potomac River Estuary near Washington, D.C.\n \n \n \n\n\n \n Phelps, H. L.\n\n\n \n\n\n\n Estuaries. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{phelps_asiatic_1994,\n\ttitle = {The asiatic clam ({Corbicula} fluminea) invasion and system-level ecological change in the {Potomac} {River} {Estuary} near {Washington}, {D}.{C}.},\n\tdoi = {10.2307/1352409},\n\tabstract = {The exotic freshwater clam species Corbicula fluminea (Asiatic clam) was first reported in the tidal freshwater Potomac estuary near Washington, D.C., in 1977, and was found in benthic surveys, conducted in 1978, 1982, 1984, 1986, and 1992. In 1981 a tripling of water clarity was reported in the region of the clam beds, followed in 1983 by reapperance of submerged aquatic vegetation (SAV) absent for 50 yr. Submerged aquatic vegetation (SAV) has been surveyed and mapped over the entire Potomac estuary region in almost every year from 1976 to 1993 by aerial photography, as part of the United States Environmental Protection Agency's Chesapeake Bay program. Fish surveys in 1986 found populations increased up to 7× in beds of SAV. Starting in 1984, the Washington, D.C. Christmas Bird Census reported significant increases in several aquatic bird populations both nonmigratory and migratory. An extensive benthic survey in September 1986 estimated a spring-summer population of 8.7×106 kg Asiatic clams (wet weight including shell) in the 5-km region of the Potomac below Washington, D.C. This population was calculated as having the capacity to filter one-third to all of the water in this region of the estuary daily, depending on river flow. The 1986 clam population was smaller than that of 1984 and the 1992 population was 25\\% of that in 1986. Since 1986, SAV acreage has been decreasing in this area of the Potomac. Aquatic bird populations have declined. Yearly nuisance algae (Microcystis) blooms, which had been absent since 1983, reappeared in 1993. This paper presents evidence to support the theory the invasive Asiatic clam population in the 10 km below Washington, D.C., was responsible for SAV resurgence through filtration affecting turbidity. It suggests the clam populations triggered system-level changes in biota, including increase and decrease in local Potomac estuary populations (SAV, bird, fish, algae) over 10 yr, from 1983 to 1993. Major changes in the Asiatic clam population took place approximately 2 yr before parallel changes in SAV acreage were observed. © 1994 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Phelps, Harriette L.},\n\tyear = {1994},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The exotic freshwater clam species Corbicula fluminea (Asiatic clam) was first reported in the tidal freshwater Potomac estuary near Washington, D.C., in 1977, and was found in benthic surveys, conducted in 1978, 1982, 1984, 1986, and 1992. In 1981 a tripling of water clarity was reported in the region of the clam beds, followed in 1983 by reapperance of submerged aquatic vegetation (SAV) absent for 50 yr. Submerged aquatic vegetation (SAV) has been surveyed and mapped over the entire Potomac estuary region in almost every year from 1976 to 1993 by aerial photography, as part of the United States Environmental Protection Agency's Chesapeake Bay program. Fish surveys in 1986 found populations increased up to 7× in beds of SAV. Starting in 1984, the Washington, D.C. Christmas Bird Census reported significant increases in several aquatic bird populations both nonmigratory and migratory. An extensive benthic survey in September 1986 estimated a spring-summer population of 8.7×106 kg Asiatic clams (wet weight including shell) in the 5-km region of the Potomac below Washington, D.C. This population was calculated as having the capacity to filter one-third to all of the water in this region of the estuary daily, depending on river flow. The 1986 clam population was smaller than that of 1984 and the 1992 population was 25% of that in 1986. Since 1986, SAV acreage has been decreasing in this area of the Potomac. Aquatic bird populations have declined. Yearly nuisance algae (Microcystis) blooms, which had been absent since 1983, reappeared in 1993. This paper presents evidence to support the theory the invasive Asiatic clam population in the 10 km below Washington, D.C., was responsible for SAV resurgence through filtration affecting turbidity. It suggests the clam populations triggered system-level changes in biota, including increase and decrease in local Potomac estuary populations (SAV, bird, fish, algae) over 10 yr, from 1983 to 1993. Major changes in the Asiatic clam population took place approximately 2 yr before parallel changes in SAV acreage were observed. © 1994 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Resource protection for waterbirds in Chesapeake bay.\n \n \n \n\n\n \n Erwin, R. M.; Haramis, G. M.; Krementz, D. G.; and Funderburk, S. L.\n\n\n \n\n\n\n Environmental Management. 1993.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{erwin_resource_1993,\n\ttitle = {Resource protection for waterbirds in {Chesapeake} bay},\n\tdoi = {10.1007/BF02393723},\n\tabstract = {Many living resources in the Chesapeake Bay estuary have deteriorated over the past 50 years. As a result, many governmental committees, task forces, and management plans have been established. Most of the recommendations for implementing a bay cleanup focus on reducing sediments and nutrient flow into the watershed. We emphasize that habitat requirements other than water quality are necessary for the recovery of much of the bay's avian wildlife, and we use a waterbird example as illustration. Some of these needs are: (1) protection of fast-eroding islands, or creation of new ones by dredge deposition to improve nesting habitat for American black ducks (Anas rubripes), great blue herons (Ardea herodias), and other associated wading birds; (2) conservation of remaining brackish marshes, especially near riparian areas, for feeding black ducks, wading birds, and wood ducks (Aix sponsa); (3) establishment of sanctuaries in open-water, littoral zones to protect feeding and/or roosting areas for diving ducks such as canvasbacks (Aythya valisineria) and redheads (Aythya americana), and for bald eagles (Haliaeetus leucocephalus); and (4) limitation of disturbance by boaters around nesting islands and open-water feeding areas. Land (or water) protection measures for waterbirds need to include units at several different spatial scales, ranging from "points" (e.g., a colony site) to large-area resources (e.g., a marsh or tributary for feeding). Planning to conserve large areas of both land and water can be achieved following a biosphere reserve model. Existing interagency committees in the Chesapeake Bay Program could be more effective in developing such a model for wildlife and fisheries resources. © 1993 Springer-Verlag New York Inc.},\n\tjournal = {Environmental Management},\n\tauthor = {Erwin, R. Michael and Haramis, G. Michael and Krementz, David G. and Funderburk, Steven L.},\n\tyear = {1993},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Many living resources in the Chesapeake Bay estuary have deteriorated over the past 50 years. As a result, many governmental committees, task forces, and management plans have been established. Most of the recommendations for implementing a bay cleanup focus on reducing sediments and nutrient flow into the watershed. We emphasize that habitat requirements other than water quality are necessary for the recovery of much of the bay's avian wildlife, and we use a waterbird example as illustration. Some of these needs are: (1) protection of fast-eroding islands, or creation of new ones by dredge deposition to improve nesting habitat for American black ducks (Anas rubripes), great blue herons (Ardea herodias), and other associated wading birds; (2) conservation of remaining brackish marshes, especially near riparian areas, for feeding black ducks, wading birds, and wood ducks (Aix sponsa); (3) establishment of sanctuaries in open-water, littoral zones to protect feeding and/or roosting areas for diving ducks such as canvasbacks (Aythya valisineria) and redheads (Aythya americana), and for bald eagles (Haliaeetus leucocephalus); and (4) limitation of disturbance by boaters around nesting islands and open-water feeding areas. Land (or water) protection measures for waterbirds need to include units at several different spatial scales, ranging from \"points\" (e.g., a colony site) to large-area resources (e.g., a marsh or tributary for feeding). Planning to conserve large areas of both land and water can be achieved following a biosphere reserve model. Existing interagency committees in the Chesapeake Bay Program could be more effective in developing such a model for wildlife and fisheries resources. © 1993 Springer-Verlag New York Inc.\n
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\n \n\n \n \n \n \n \n Swimming velocities and behavior of blue crab (Callinectes sapidus rathbun) megalopae in still and flowing water.\n \n \n \n\n\n \n Luckenbach, M. W.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1992.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{luckenbach_swimming_1992,\n\ttitle = {Swimming velocities and behavior of blue crab ({Callinectes} sapidus rathbun) megalopae in still and flowing water},\n\tdoi = {10.2307/1352691},\n\tabstract = {Habitat selection capabilities of the recruiting larval stages of marine invertebrates are limited, in part, by their ability to maneuver in flowing water. Distributional and experimental evidence suggest that blue crab (Callinectes sapidus) megalopae may preferentially settle into vegetated habitats. However, the behavior and swimming capabilities of megalopae in flowing water have not previously been investigated. Laboratory experiments were conducted in a small, recirculating seawater flume to determine the swimming response of megalopae to varying flow velocities. Nighttime trials were conducted at six flow velocities: 0, 1.9, 3.6, 4.8, 6.3, and 9.3 cm s-1. Behavior and swimming velocities of field-collected C. sapidus megalopae were video recorded. Megalopae exhibited negative phototaxis and were found in the water column at all flows in the dark. The maximum sustained swimming speed observed was 12.6 cm s-1 and the mean swimming speed in still water was 5.0 cm s-1, with short bursts in excess of 20 cm s-1. Megalopae frequently oriented into the current and were capable of swimming upstream against the current at flow speeds {\\textbackslash}textless4.8 cm s-1; at greater velocities they were not able to do so. The results suggest that at low to moderate current velocities C. sapidus megalopae have the ability to actively move in search of settlement sites and to maintain their positions in desirable sites rather than relying strictly on passive movements by currents. © 1992 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Luckenbach, Mark W. and Orth, Robert J.},\n\tyear = {1992},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Habitat selection capabilities of the recruiting larval stages of marine invertebrates are limited, in part, by their ability to maneuver in flowing water. Distributional and experimental evidence suggest that blue crab (Callinectes sapidus) megalopae may preferentially settle into vegetated habitats. However, the behavior and swimming capabilities of megalopae in flowing water have not previously been investigated. Laboratory experiments were conducted in a small, recirculating seawater flume to determine the swimming response of megalopae to varying flow velocities. Nighttime trials were conducted at six flow velocities: 0, 1.9, 3.6, 4.8, 6.3, and 9.3 cm s-1. Behavior and swimming velocities of field-collected C. sapidus megalopae were video recorded. Megalopae exhibited negative phototaxis and were found in the water column at all flows in the dark. The maximum sustained swimming speed observed was 12.6 cm s-1 and the mean swimming speed in still water was 5.0 cm s-1, with short bursts in excess of 20 cm s-1. Megalopae frequently oriented into the current and were capable of swimming upstream against the current at flow speeds \\textless4.8 cm s-1; at greater velocities they were not able to do so. The results suggest that at low to moderate current velocities C. sapidus megalopae have the ability to actively move in search of settlement sites and to maintain their positions in desirable sites rather than relying strictly on passive movements by currents. © 1992 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n A perspective on plant-animal interactions in seagrasses: physical and biological determinats influencing plant and animal abundance.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Plant-Animal Interactions in the marine Benthos. 1992.\n ISBN: 9780198577546\n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_perspective_1992,\n\ttitle = {A perspective on plant-animal interactions in seagrasses: physical and biological determinats influencing plant and animal abundance},\n\tabstract = {Review of experimental work on predator-prey, grazer-nutrient-seagrass and physical factors-larval supply interactions. Biomass and diversity higher zthan in unveg. areas},\n\tjournal = {Plant-Animal Interactions in the marine Benthos},\n\tauthor = {Orth, Robert J.},\n\tyear = {1992},\n\tnote = {ISBN: 9780198577546},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Review of experimental work on predator-prey, grazer-nutrient-seagrass and physical factors-larval supply interactions. Biomass and diversity higher zthan in unveg. areas\n
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\n \n\n \n \n \n \n \n Population dynamics of blue crabs Callinectes sapidus Rathbun in a lower Chesapeake Bay tidal marsh creek.\n \n \n \n\n\n \n van Montfrans, J.; Ryer, C. H.; and Orth, R. J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1991.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{van_montfrans_population_1991,\n\ttitle = {Population dynamics of blue crabs {Callinectes} sapidus {Rathbun} in a lower {Chesapeake} {Bay} tidal marsh creek},\n\tdoi = {10.1016/S0022-0981(05)80002-4},\n\tabstract = {The dynamics of a blue crab Callinectes sapidus Rathbun population residing in an ≈ 10 000-m2 tidal marsh creek, lower Chesapeake Bay, Virginia, were examined. During the 65-day, single-mark, multiple-recapture study, crabs were marked with an internal coded wire tag injected into the left or right basal muscle of the 5th pereiopod. Estimates of population size in the creek ranged from 799 to 1564 individuals throughout the study, yielding density estimates of 0.08-0.15 ind·m-2. The population was dominated by medium-sized (50-100 mm carapace width) individuals. Loss of crabs (emigration plus mortality) was calculated from tag-recovery data, and immigration was determined as the difference between the change in population size and the loss of individuals. Crab movement into and out of the creek was not tidally driven. Median residency (tag half life) was 8-12 days, with population turnover exceeding 65 days. Residency estimates were used as an indication of potential marsh production exchange with other adiacent habitats. On short time scales (i.e., tidally or daily), blue crab fecal deposition may not be an important mechanism for transferring marsh production to adjacent estuarine habitats. Instead, incorporation of marsh production into body tissues (i.e., growth) followed by emigration over longer time scales (i.e., weeks to months) appears to play a greater role in coupling marsh production with adjacent habitats. © 1991 Elsevier Science Publishers B.V. All rights reserved.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {van Montfrans, Jacques and Ryer, Clifford H. and Orth, Robert J.},\n\tyear = {1991},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The dynamics of a blue crab Callinectes sapidus Rathbun population residing in an ≈ 10 000-m2 tidal marsh creek, lower Chesapeake Bay, Virginia, were examined. During the 65-day, single-mark, multiple-recapture study, crabs were marked with an internal coded wire tag injected into the left or right basal muscle of the 5th pereiopod. Estimates of population size in the creek ranged from 799 to 1564 individuals throughout the study, yielding density estimates of 0.08-0.15 ind·m-2. The population was dominated by medium-sized (50-100 mm carapace width) individuals. Loss of crabs (emigration plus mortality) was calculated from tag-recovery data, and immigration was determined as the difference between the change in population size and the loss of individuals. Crab movement into and out of the creek was not tidally driven. Median residency (tag half life) was 8-12 days, with population turnover exceeding 65 days. Residency estimates were used as an indication of potential marsh production exchange with other adiacent habitats. On short time scales (i.e., tidally or daily), blue crab fecal deposition may not be an important mechanism for transferring marsh production to adjacent estuarine habitats. Instead, incorporation of marsh production into body tissues (i.e., growth) followed by emigration over longer time scales (i.e., weeks to months) appears to play a greater role in coupling marsh production with adjacent habitats. © 1991 Elsevier Science Publishers B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Littoral and intertidal systems in the mid-Atlantic coast of the United States.\n \n \n \n\n\n \n Orth, R. J.; Heck, K. L.; and Diaz, R. J.\n\n\n \n\n\n\n Intertidal and littoral ecosystems. 1991.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_littoral_1991,\n\ttitle = {Littoral and intertidal systems in the mid-{Atlantic} coast of the {United} {States}},\n\tabstract = {The littoral and intertidal habitats of the US coast from Cape Cod to (and including) Georgia are characterised by a lack of rocky substrates and by a pronounced annual temperature range (up to 40°C). Coastal lagoons, bays behind barrier islands and estuaries often possess seagrass beds. Comments are made on the physical setting and sediments; environmental variables; faunal and floral characteristics of sand and mud; functional relations (biological interactions - where mutualisms and coexistence are more typical than competition, and biomass, production and decomposition, food webs, and nutrient cycling). -P.J.Jarvis},\n\tjournal = {Intertidal and littoral ecosystems},\n\tauthor = {Orth, R. J. and Heck, K. L. and Diaz, R. J.},\n\tyear = {1991},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The littoral and intertidal habitats of the US coast from Cape Cod to (and including) Georgia are characterised by a lack of rocky substrates and by a pronounced annual temperature range (up to 40°C). Coastal lagoons, bays behind barrier islands and estuaries often possess seagrass beds. Comments are made on the physical setting and sediments; environmental variables; faunal and floral characteristics of sand and mud; functional relations (biological interactions - where mutualisms and coexistence are more typical than competition, and biomass, production and decomposition, food webs, and nutrient cycling). -P.J.Jarvis\n
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\n \n\n \n \n \n \n \n Movement of blue crab megalopae into Chesapeake Bay: Observational evidence for a wind-driven mechanism.\n \n \n \n\n\n \n Goodrich, D; van Montfrans, J; and Orth, R\n\n\n \n\n\n\n Bull. Mar. Sci.. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{goodrich_movement_1990,\n\ttitle = {Movement of blue crab megalopae into {Chesapeake} {Bay}: {Observational} evidence for a wind-driven mechanism.},\n\tabstract = {AB: It is known that blue crab larvae mature offshore and that postlarvae must return to the estuary for further development. A three year time series of megalopae from inside Chesapeake Bay reveals an irregular, spiky distribution in time, suggesting an episodic recruitment process. Prominent features of circulation at the Bay entrance are wind-driven exchange events, and the magnitude of wind-induced changes in Bay volume can be calculated using tide data. A total of 13 of 18 megalopal peaks during the three years occurred during positive volume anomalies. In particular, the largest peak of 1985 occurred during the massive storm surge associated with Hurricane Juan. Analysis of 28 years of subtidal volume data from the Bay indicates that an average of 10 major inflow events per year occur during the period when megalopae are present. This indicates that these wind-induced events are not fortuitous but rather are a stable feature of the flow climate at the Bay entrance},\n\tjournal = {Bull. Mar. Sci.},\n\tauthor = {Goodrich, D and van Montfrans, J and Orth, R},\n\tyear = {1990},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n AB: It is known that blue crab larvae mature offshore and that postlarvae must return to the estuary for further development. A three year time series of megalopae from inside Chesapeake Bay reveals an irregular, spiky distribution in time, suggesting an episodic recruitment process. Prominent features of circulation at the Bay entrance are wind-driven exchange events, and the magnitude of wind-induced changes in Bay volume can be calculated using tide data. A total of 13 of 18 megalopal peaks during the three years occurred during positive volume anomalies. In particular, the largest peak of 1985 occurred during the massive storm surge associated with Hurricane Juan. Analysis of 28 years of subtidal volume data from the Bay indicates that an average of 10 major inflow events per year occur during the period when megalopae are present. This indicates that these wind-induced events are not fortuitous but rather are a stable feature of the flow climate at the Bay entrance\n
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\n \n\n \n \n \n \n \n Utilization of a seagrass meadow and tidal marsh creek by blue crabs Callinectes sapidus. II. Spatial and temporal patterns of molting.\n \n \n \n\n\n \n Ryer, C. H.; Van Montfrans, J.; and Orth, R. J.\n\n\n \n\n\n\n Bulletin of Marine Science. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ryer_utilization_1990,\n\ttitle = {Utilization of a seagrass meadow and tidal marsh creek by blue crabs {Callinectes} sapidus. {II}. {Spatial} and temporal patterns of molting},\n\tabstract = {Blue crabs were collected weekly from a lower Chesapeake Bay seagrass meadow and adjacent tidal marsh creek over July-August 1987. Molting activity was greater in the grassbed than in the marsh creek, and greater for small crabs and females. The difference between the habitats in molting activity decreased from the 1st to the 2nd month of sampling, possibly in response to seasonal decline in seagrass biomass. The proportion of small ({\\textbackslash}textless70 mm) females in both habitats was greatest on full moons. There was a lunar rhythm of molting activity by large crabs (≥70 mm), with peak molting activity on full moons. Small crabs demonstrated a similar, in seagrass meadows, possibly, but nonsignificant rhythm of molting. Blue crabs approaching ecolysis aggregate taking advantage of the refuge from predation that this structurally complex habitat affords. Lunar rhythmicity of molting activity may further reduce predation mortality through a dilution effect. -from Authors},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {Ryer, C. H. and Van Montfrans, J. and Orth, R. J.},\n\tyear = {1990},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Blue crabs were collected weekly from a lower Chesapeake Bay seagrass meadow and adjacent tidal marsh creek over July-August 1987. Molting activity was greater in the grassbed than in the marsh creek, and greater for small crabs and females. The difference between the habitats in molting activity decreased from the 1st to the 2nd month of sampling, possibly in response to seasonal decline in seagrass biomass. The proportion of small (\\textless70 mm) females in both habitats was greatest on full moons. There was a lunar rhythm of molting activity by large crabs (≥70 mm), with peak molting activity on full moons. Small crabs demonstrated a similar, in seagrass meadows, possibly, but nonsignificant rhythm of molting. Blue crabs approaching ecolysis aggregate taking advantage of the refuge from predation that this structurally complex habitat affords. Lunar rhythmicity of molting activity may further reduce predation mortality through a dilution effect. -from Authors\n
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\n \n\n \n \n \n \n \n Utilization of marsh and seagrass habitats by early stages of Callinectes sapidus: a latitudinal perspective.\n \n \n \n\n\n \n Orth, R. J.; and Van Montfrans, J.\n\n\n \n\n\n\n Bulletin of Marine Science. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_utilization_1990,\n\ttitle = {Utilization of marsh and seagrass habitats by early stages of {Callinectes} sapidus: a latitudinal perspective},\n\tabstract = {Seagrass beds and marshes have been identified as important nurseries for blue crab. Regional comparisons of blue crab catch data regressed on habitat area were not significant whereas similar comparisons within the Gulf region showed a significant positive relationship of crab harvest with total vegetated area. Thus, the quantity of habitat may be important over small latitudinal scales but other factors could affect population abundances across broad latitudinal distances. Latitudinal differences in habitat use may result from alternate modes of settlement via megalopae or recruitment by juveniles, active or passive habitat selection, post-settlement mortality and food quality and quantity. Tidal regimes and coastal morphology in relation to physical processes may influence accessibility of important habitats by settling or recruiting individuals and thus be equally important. -from Authors},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {Orth, R. J. and Van Montfrans, J.},\n\tyear = {1990},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Seagrass beds and marshes have been identified as important nurseries for blue crab. Regional comparisons of blue crab catch data regressed on habitat area were not significant whereas similar comparisons within the Gulf region showed a significant positive relationship of crab harvest with total vegetated area. Thus, the quantity of habitat may be important over small latitudinal scales but other factors could affect population abundances across broad latitudinal distances. Latitudinal differences in habitat use may result from alternate modes of settlement via megalopae or recruitment by juveniles, active or passive habitat selection, post-settlement mortality and food quality and quantity. Tidal regimes and coastal morphology in relation to physical processes may influence accessibility of important habitats by settling or recruiting individuals and thus be equally important. -from Authors\n
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\n \n\n \n \n \n \n \n Daily, monthly and annual settlement patterns by Callinectes sapidus and Neopanope sayi megalopae on artificial collectors deployed in the York River, Virginia: 1985-1988.\n \n \n \n\n\n \n Van Montfrans, J.; Peery, C. A.; and Orth, R. J.\n\n\n \n\n\n\n Bulletin of Marine Science. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{van_montfrans_daily_1990,\n\ttitle = {Daily, monthly and annual settlement patterns by {Callinectes} sapidus and {Neopanope} sayi megalopae on artificial collectors deployed in the {York} {River}, {Virginia}: 1985-1988},\n\tabstract = {Callinectes sapidus, an exported estuarine species, and Neopanope sayi, a retained estuarine species, were the numerically dominant colonizers of collectors. C. sapidus settlement was highly episodic (1-3-day duration) and significantly associated with the full moon period (lunar day 15-22). The temporal mean of settlement for C. sapidus each year fell within a 12-day period (24 September-6 October). C. sapidus megalopae settled over a broad range of temperatures (7-31°C) extending into the fall months when resident predators become inactive or migrate to deeper water. In contrast, N. sayi settled throughout the lunar month with no significant lunar or tidal periodicity. Settlement by N. sayi occurred over a narrower temperature range (12-31°C) and mean annual settlement occurred earlier within a 12-day period from 9-21 September. -from Authors},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {Van Montfrans, J. and Peery, C. A. and Orth, R. J.},\n\tyear = {1990},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Callinectes sapidus, an exported estuarine species, and Neopanope sayi, a retained estuarine species, were the numerically dominant colonizers of collectors. C. sapidus settlement was highly episodic (1-3-day duration) and significantly associated with the full moon period (lunar day 15-22). The temporal mean of settlement for C. sapidus each year fell within a 12-day period (24 September-6 October). C. sapidus megalopae settled over a broad range of temperatures (7-31°C) extending into the fall months when resident predators become inactive or migrate to deeper water. In contrast, N. sayi settled throughout the lunar month with no significant lunar or tidal periodicity. Settlement by N. sayi occurred over a narrower temperature range (12-31°C) and mean annual settlement occurred earlier within a 12-day period from 9-21 September. -from Authors\n
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\n \n\n \n \n \n \n \n Variation in planktonic availability and settlement of blue crab megalopae in the York River, Virginia.\n \n \n \n\n\n \n Olmi, E. J.; Van Montfrans, J.; Lipcius, R. N.; Orth, R. J.; and Sadler, P. W.\n\n\n \n\n\n\n Bulletin of Marine Science. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{olmi_variation_1990,\n\ttitle = {Variation in planktonic availability and settlement of blue crab megalopae in the {York} {River}, {Virginia}},\n\tabstract = {Callinectes sapidus megalopae and juveniles were sampled in the plankton and on natural (grassbeds) and artificial settlement substrates (collectors). Spatial patterns of abundance were not consistent across habitats (plankton, artificial collectors and grassbeds) or time. Densities of planktonic megalopae were homogeneous at 1-2 m (within site) but varied at spatial scales of hundreds of meters (between sites) and kilometers (between areas). Settled megalopae were distributed unevenly within and between sites, but their abundance did not differ between areas. Densities of megalopae and first-stage juveniles in grassbeds correlated with megalopal abundance in the plankton. Settlement on collectors, however, was not correlated with planktonic density, probably because of low sample size. Total juvenile abundance exhibited lower spatial and temporal variability in grassbeds than that of megalopae or first-stage juveniles, suggesting high post-settlement mortality or migration from areas of high settlement. -from Authors},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {Olmi, E. J. and Van Montfrans, J. and Lipcius, R. N. and Orth, R. J. and Sadler, P. W.},\n\tyear = {1990},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Callinectes sapidus megalopae and juveniles were sampled in the plankton and on natural (grassbeds) and artificial settlement substrates (collectors). Spatial patterns of abundance were not consistent across habitats (plankton, artificial collectors and grassbeds) or time. Densities of planktonic megalopae were homogeneous at 1-2 m (within site) but varied at spatial scales of hundreds of meters (between sites) and kilometers (between areas). Settled megalopae were distributed unevenly within and between sites, but their abundance did not differ between areas. Densities of megalopae and first-stage juveniles in grassbeds correlated with megalopal abundance in the plankton. Settlement on collectors, however, was not correlated with planktonic density, probably because of low sample size. Total juvenile abundance exhibited lower spatial and temporal variability in grassbeds than that of megalopae or first-stage juveniles, suggesting high post-settlement mortality or migration from areas of high settlement. -from Authors\n
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\n \n\n \n \n \n \n \n Variations in structure of estuarine fish communities in relation to abundance of submersed vascular plants.\n \n \n \n\n\n \n Lubbers, L; Boynton, W.; and Kemp, W.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{lubbers_variations_1990,\n\ttitle = {Variations in structure of estuarine fish communities in relation to abundance of submersed vascular plants},\n\tdoi = {10.3354/meps065001},\n\tabstract = {Fish communities and other ecological variables were sampled for 6 mo (May to October) in successive years (1979, 1980) at vegetated and non-vegetated areas in 2 distinctively different littoral zones (an open bay and a protected cove) of mid-salinity Chesapeake Bay, USA. Fish abundance, biomass and species richness were h∼gher in vegetated areas at both sites, and were significantly correlated with macrophyte biomass Diel patterns of fish abundance varied, but highest catches generally occurred at dusk or at night. At one sampling site fish assemblages were dominated by smaller individuals in the vegetated area, suggesting an attraction of juveniles to macrophyte beds for food or refuge from predation. Larger piscivorous fish, which were also caught in greater numbers in vegetated areas, may have been attracted there by higher densities of forage fish. At the cove site the biomass of Paleomonetes sp. was comparable to that of the fish community towards the end of the plant growing season. Benthic infauna were also more abundant in vegetated areas at both sites, and stomach analyses indicated these organisms to be the dominant food resources for common fishes. Diets were generally non-selective in non-vegetated areas while highly selective for epiphytic fauna in macrophyte beds. Fish stomachs were also significantly fuller in vegetated areas, indicating generally greater feeding success. Fish production varied among major species but was higher overall at vegetated areas, following the seasonal patterns of primary production. Most of the differences in fish production between areas were attributable to higher instantaneous growth rates rather than higher biomass. It appears that the greater abundance and species richness of fish assemblages in vegetated areas of this region of Chesapeake Bay resulted from the attractiveness of these habitats as rich sources of preferred foods.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Lubbers, L and Boynton, WR and Kemp, WM},\n\tyear = {1990},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Fish communities and other ecological variables were sampled for 6 mo (May to October) in successive years (1979, 1980) at vegetated and non-vegetated areas in 2 distinctively different littoral zones (an open bay and a protected cove) of mid-salinity Chesapeake Bay, USA. Fish abundance, biomass and species richness were h∼gher in vegetated areas at both sites, and were significantly correlated with macrophyte biomass Diel patterns of fish abundance varied, but highest catches generally occurred at dusk or at night. At one sampling site fish assemblages were dominated by smaller individuals in the vegetated area, suggesting an attraction of juveniles to macrophyte beds for food or refuge from predation. Larger piscivorous fish, which were also caught in greater numbers in vegetated areas, may have been attracted there by higher densities of forage fish. At the cove site the biomass of Paleomonetes sp. was comparable to that of the fish community towards the end of the plant growing season. Benthic infauna were also more abundant in vegetated areas at both sites, and stomach analyses indicated these organisms to be the dominant food resources for common fishes. Diets were generally non-selective in non-vegetated areas while highly selective for epiphytic fauna in macrophyte beds. Fish stomachs were also significantly fuller in vegetated areas, indicating generally greater feeding success. Fish production varied among major species but was higher overall at vegetated areas, following the seasonal patterns of primary production. Most of the differences in fish production between areas were attributable to higher instantaneous growth rates rather than higher biomass. It appears that the greater abundance and species richness of fish assemblages in vegetated areas of this region of Chesapeake Bay resulted from the attractiveness of these habitats as rich sources of preferred foods.\n
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\n \n\n \n \n \n \n \n Planktonic availability, molt stage and settlement of blue crab postlarvae.\n \n \n \n\n\n \n Lipcius, R.; Olmi, E.; and van Montfrans, J\n\n\n \n\n\n\n Marine Ecology Progress Series. 1989.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{lipcius_planktonic_1989,\n\ttitle = {Planktonic availability, molt stage and settlement of blue crab postlarvae},\n\tdoi = {10.3354/meps058235},\n\tabstract = {The authors quantified spatio-temporal variation in molt stage (developmental state) of blue crab Callinectes sapidus megalopae (postlarvae), and the relationship between planktonic availability, molt stage and settlement of megalopae during peak settlement in Chesapeake Bay, USA Settlement was significantly correlated with the planktonic availabilityof megalopae. Developmental state of megalopae also appeared influential in settlement because bluse crab megalopae displayed quantifiable changes in molt stage; molt stage of megalopae varied on a temporal scale of days to 1 mo or more, and a spatial scale of kilometers, apparently reflecting the physiological progression through the molt cycle by megalopae pulsing through settlement habitats; and molt stage of megalopae advanced in collections from the plankton, on artifical settlement habitats, and in the benthos, indicating the approach to settlement, metamorphosis and a benthic existence.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Lipcius, RN and Olmi, EJ and van Montfrans, J},\n\tyear = {1989},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The authors quantified spatio-temporal variation in molt stage (developmental state) of blue crab Callinectes sapidus megalopae (postlarvae), and the relationship between planktonic availability, molt stage and settlement of megalopae during peak settlement in Chesapeake Bay, USA Settlement was significantly correlated with the planktonic availabilityof megalopae. Developmental state of megalopae also appeared influential in settlement because bluse crab megalopae displayed quantifiable changes in molt stage; molt stage of megalopae varied on a temporal scale of days to 1 mo or more, and a spatial scale of kilometers, apparently reflecting the physiological progression through the molt cycle by megalopae pulsing through settlement habitats; and molt stage of megalopae advanced in collections from the plankton, on artifical settlement habitats, and in the benthos, indicating the approach to settlement, metamorphosis and a benthic existence.\n
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\n \n\n \n \n \n \n \n Pipefish foraging: effects of fish size, prey size and altered habitat complexity.\n \n \n \n\n\n \n Ryer, C.\n\n\n \n\n\n\n Marine Ecology Progress Series, 48(Dawson 1982): 37–45. 1988.\n Number: Dawson 1982 ISBN: 0171-8630\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ryer_pipefish_1988,\n\ttitle = {Pipefish foraging: effects of fish size, prey size and altered habitat complexity},\n\tvolume = {48},\n\tdoi = {10.3354/meps048037},\n\tabstract = {Laboratory experiments determined the effects of 2 levels of habitat complexity upon pipefish Syngnathus fuscus foraging for amphipods. Habitats were composed of equal densities of either narrow (low complexity) or wide (high complexity) leafed artificial seagrass. Response to habitat - as measured by rate of encounter with amphipods, probability of attack after encounter, probability of success after attack, and overall rate of amphipod consumption - was determined for combinations of 2 fish size classes and 3 amphlpod size classes. Small fish did not respond to changes in habitat complexity, while large fish \\&d. Large fish encountered fewer amphipods in the high than in the low complexity habitat. In general encounter rate increased with amphipod size. Large fish attack probabil- ity was negatively related to amphipod size in the narrow leaf habitat, but positively related to amphipod size in the wide leaf habitat. Small fish attack probability was negatively related to amphipod size in both habitats. Success was negatively related to prey size and greater for large than for small fish. and showed no overall effect of habitat. The position that amphipods occupy in the structure of vegetation in part determines their vulnerability to predation, a criterion by which pipefish appear to select prey. In this respect pipefish behavior is flexible, allowing adjustment of foraging tactics to match habitat constraints. Results suggest that relative sizes of predator and prey are important factors in determining the effect of structural complexity upon predator-prey dynamics. INTRODUCTION},\n\tnumber = {Dawson 1982},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Ryer, Ch},\n\tyear = {1988},\n\tnote = {Number: Dawson 1982\nISBN: 0171-8630},\n\tkeywords = {Animal Interactions},\n\tpages = {37--45},\n}\n\n
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\n Laboratory experiments determined the effects of 2 levels of habitat complexity upon pipefish Syngnathus fuscus foraging for amphipods. Habitats were composed of equal densities of either narrow (low complexity) or wide (high complexity) leafed artificial seagrass. Response to habitat - as measured by rate of encounter with amphipods, probability of attack after encounter, probability of success after attack, and overall rate of amphipod consumption - was determined for combinations of 2 fish size classes and 3 amphlpod size classes. Small fish did not respond to changes in habitat complexity, while large fish &d. Large fish encountered fewer amphipods in the high than in the low complexity habitat. In general encounter rate increased with amphipod size. Large fish attack probabil- ity was negatively related to amphipod size in the narrow leaf habitat, but positively related to amphipod size in the wide leaf habitat. Small fish attack probability was negatively related to amphipod size in both habitats. Success was negatively related to prey size and greater for large than for small fish. and showed no overall effect of habitat. The position that amphipods occupy in the structure of vegetation in part determines their vulnerability to predation, a criterion by which pipefish appear to select prey. In this respect pipefish behavior is flexible, allowing adjustment of foraging tactics to match habitat constraints. Results suggest that relative sizes of predator and prey are important factors in determining the effect of structural complexity upon predator-prey dynamics. INTRODUCTION\n
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\n \n\n \n \n \n \n \n Nearshore ichthyoplankton associated with seagrass beds in the lower Chesapeake Bay.\n \n \n \n\n\n \n Olney, J.; and Boehlert, G.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1988.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{olney_nearshore_1988,\n\ttitle = {Nearshore ichthyoplankton associated with seagrass beds in the lower {Chesapeake} {Bay}},\n\tdoi = {10.3354/meps045033},\n\tabstract = {In this study the authors describe the egg, larval, and juvenile fish assemblages in shallow areas of submerged aquatic vegetation (SAV) of the lower Chesapeake Bay and compare them with those over the adjacent, shallow sand habitat. The SAV habitats were not important spawning sites for species with pelagic eggs, but were important for species brooding eggs or with demersal eggs. Overall, collections were dominated by the bay anchovy Anchoa mitchilli , but contained many species not commonly found in the midchannel ichthyoplankton described in earlier studies. Results suggest that SAV areas do not play an important nursery role for pelagic eggs and early larvae, which may suffer increased predation by planktivores in these areas. Later stages, however, may benefit from reduced predation pressure from piscivores and thus benefit from association with SAV},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Olney, JE and Boehlert, GW},\n\tyear = {1988},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n In this study the authors describe the egg, larval, and juvenile fish assemblages in shallow areas of submerged aquatic vegetation (SAV) of the lower Chesapeake Bay and compare them with those over the adjacent, shallow sand habitat. The SAV habitats were not important spawning sites for species with pelagic eggs, but were important for species brooding eggs or with demersal eggs. Overall, collections were dominated by the bay anchovy Anchoa mitchilli , but contained many species not commonly found in the midchannel ichthyoplankton described in earlier studies. Results suggest that SAV areas do not play an important nursery role for pelagic eggs and early larvae, which may suffer increased predation by planktivores in these areas. Later stages, however, may benefit from reduced predation pressure from piscivores and thus benefit from association with SAV\n
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\n \n\n \n \n \n \n \n The rôle of submerged aquatic vegetation in influencing the abundance of nekton on contiguous tidal fresh-water marshes.\n \n \n \n\n\n \n Rozas, L. P.; and Odum, W. E.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1988.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{rozas_rosubmerged_1988,\n\ttitle = {The rôle of submerged aquatic vegetation in influencing the abundance of nekton on contiguous tidal fresh-water marshes},\n\tdoi = {10.1016/0022-0981(88)90144-X},\n\tabstract = {Field experiments were conducted in which submerged aquatic vegetation (SAV) was either removed or added to tidal freshwater marsh creeks and nekton was sampled on adjacent marshes with flume nets. These experiments were designed to determine whether the presence of SAV in tidal creeks influences the abundance of fishes and grass shrimp Palaemonetes pugio Holthuis on contiguous marshes. In experiments where SAV was removed from tidal creeks, the number of grass shrimp on adjacent marshes decreased, but the average density of fishes, mostly mummichogs Fundulus heteroclitus (Linnaeus) and banded killifish F. diaphanus (Lesueur), was not reduced. The abundance of grass shrimp increased on marshes where artificial SAV was added to adjacent tidal creeks without natural SAV, but the abundance of fish did not increase. The density of marsh plants and marsh elevation were investigated as additional factors that could influence the abundance of nekton on the marsh surface, but we found no evidence that these factors were important. We conclude that the proximity of SAV and the depth of adjacent tidal creeks are the most important factors that influence the abundance of nekton on tidal freshwater marshes. © 1987.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Rozas, Lawrence P. and Odum, William E.},\n\tyear = {1988},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Field experiments were conducted in which submerged aquatic vegetation (SAV) was either removed or added to tidal freshwater marsh creeks and nekton was sampled on adjacent marshes with flume nets. These experiments were designed to determine whether the presence of SAV in tidal creeks influences the abundance of fishes and grass shrimp Palaemonetes pugio Holthuis on contiguous marshes. In experiments where SAV was removed from tidal creeks, the number of grass shrimp on adjacent marshes decreased, but the average density of fishes, mostly mummichogs Fundulus heteroclitus (Linnaeus) and banded killifish F. diaphanus (Lesueur), was not reduced. The abundance of grass shrimp increased on marshes where artificial SAV was added to adjacent tidal creeks without natural SAV, but the abundance of fish did not increase. The density of marsh plants and marsh elevation were investigated as additional factors that could influence the abundance of nekton on the marsh surface, but we found no evidence that these factors were important. We conclude that the proximity of SAV and the depth of adjacent tidal creeks are the most important factors that influence the abundance of nekton on tidal freshwater marshes. © 1987.\n
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\n \n\n \n \n \n \n \n Food habits and distribution of wintering canvasbacks, Aythya valisineria, on Chesapeake Bay.\n \n \n \n\n\n \n Perry, M. C.; and Uhler, F. M.\n\n\n \n\n\n\n Estuaries. 1988.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{perry_food_1988,\n\ttitle = {Food habits and distribution of wintering canvasbacks, {Aythya} valisineria, on {Chesapeake} {Bay}},\n\tdoi = {10.2307/1351718},\n\tabstract = {Baltic clams (Macoma balthica) were the predominant food items of 323 canvasbacks (Aythya valisineria) collected throughout Chesapeake Bay during 1970–1979. Natural vegetation constituted 4\\% of the food volume. Widgeongrass (Ruppia maritima) and redhead grass (Potamogeton perfoliatus) constituted the greatest percent volume and frequency of occurrence among the plant species, whereas wild celery (Vallisneria americana) constituted only a trace of the food volume. These results contrast with historical records of food habits of canvasbacks in Chesapeake Bay. Canvasback population estimates during the 1970's were examined to detect annual and seasonal changes in distribution. Linear regression analyses of winter canvasback populations in the bay showed a significant decline in the upper-bay and middle-bay populations, but no significant changes in the lower-bay and Potomac River populations. The changes in winter distribution and abundance of the canvasback appear related to changes in natural food availability, which is the result of altered environmental conditions. © 1988, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Perry, Matthew C. and Uhler, Francis M.},\n\tyear = {1988},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Baltic clams (Macoma balthica) were the predominant food items of 323 canvasbacks (Aythya valisineria) collected throughout Chesapeake Bay during 1970–1979. Natural vegetation constituted 4% of the food volume. Widgeongrass (Ruppia maritima) and redhead grass (Potamogeton perfoliatus) constituted the greatest percent volume and frequency of occurrence among the plant species, whereas wild celery (Vallisneria americana) constituted only a trace of the food volume. These results contrast with historical records of food habits of canvasbacks in Chesapeake Bay. Canvasback population estimates during the 1970's were examined to detect annual and seasonal changes in distribution. Linear regression analyses of winter canvasback populations in the bay showed a significant decline in the upper-bay and middle-bay populations, but no significant changes in the lower-bay and Potomac River populations. The changes in winter distribution and abundance of the canvasback appear related to changes in natural food availability, which is the result of altered environmental conditions. © 1988, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Temporal patterns of feeding by blue crabs (Callinectes sapidus) in a tidal-marsh creek and adjacent seagrass meadow in the lower Chesapeake Bay.\n \n \n \n\n\n \n Ryer, C. H.\n\n\n \n\n\n\n Estuaries. 1987.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ryer_temporal_1987,\n\ttitle = {Temporal patterns of feeding by blue crabs ({Callinectes} sapidus) in a tidal-marsh creek and adjacent seagrass meadow in the lower {Chesapeake} {Bay}},\n\tdoi = {10.2307/1352178},\n\tabstract = {A 24-h study of blue crab feeding periodicity was conducted concurrently in a tidal marsh creek and adjacent seagrass meadow in the lower Chesapeake Bay. Crabs from the grassbed tended to have fuller guts than crabs from the marsh creek. In the grassbed, a weak trend toward nocturnal feeding was observed, with an apparent peak at dusk. During the day, crabs were not easily observed and were assumed to be feeding beneath the eelgrass canopy; at night crabs fed in the canopy. In the marsh creek, feeding was related to the tidal cycle, with guts being fullest at high tide and decreasing to lows just prior to the next high tide. This study suggests the potential importance of habitat on blue crab feeding patterns. © 1987, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Ryer, Clifford H.},\n\tyear = {1987},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n A 24-h study of blue crab feeding periodicity was conducted concurrently in a tidal marsh creek and adjacent seagrass meadow in the lower Chesapeake Bay. Crabs from the grassbed tended to have fuller guts than crabs from the marsh creek. In the grassbed, a weak trend toward nocturnal feeding was observed, with an apparent peak at dusk. During the day, crabs were not easily observed and were assumed to be feeding beneath the eelgrass canopy; at night crabs fed in the canopy. In the marsh creek, feeding was related to the tidal cycle, with guts being fullest at high tide and decreasing to lows just prior to the next high tide. This study suggests the potential importance of habitat on blue crab feeding patterns. © 1987, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Feeding ecology of the northern pipefish, Syngnathus fuscus, in a seagrass community of the lower Chesapeake Bay.\n \n \n \n\n\n \n Ryer, C. H.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1987.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{ryer_feeding_1987,\n\ttitle = {Feeding ecology of the northern pipefish, {Syngnathus} fuscus, in a seagrass community of the lower {Chesapeake} {Bay}},\n\tdoi = {10.2307/1351891},\n\tabstract = {Examination of gut contents of the northern pipefish, Syngnathus fuscus, revealed that gammarid amphipods, caprellid amphipods, isopods, and calanoid copepods were the dominant food items during the sevenmonth study period. Gammarus mucronatus, calanoid copepods, and Erichsonella attenuata were the seasonally dominant prey items in the spring, summer, and fall, respectively. G. mucronatus and calanoid copepods were consumed in approximate proportion to their numerical abundance in the environment, while E. attenuata, present in rather uniform densities throughout the study period, was extensively consumed only in the late summer and fall. An ontogenetic pattern of prey consumption was evident, in addition to the seasonal pattern. Comparison of G. mucronatus and E. attenuata size ranges from the field and in pipefish guts revealed that S. fuscus preyed upon the smaller size classes of each species, and that mean size of prey consumed was positively related to fish size. © 1987, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Ryer, Clifford H. and Orth, Robert J.},\n\tyear = {1987},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Examination of gut contents of the northern pipefish, Syngnathus fuscus, revealed that gammarid amphipods, caprellid amphipods, isopods, and calanoid copepods were the dominant food items during the sevenmonth study period. Gammarus mucronatus, calanoid copepods, and Erichsonella attenuata were the seasonally dominant prey items in the spring, summer, and fall, respectively. G. mucronatus and calanoid copepods were consumed in approximate proportion to their numerical abundance in the environment, while E. attenuata, present in rather uniform densities throughout the study period, was extensively consumed only in the late summer and fall. An ontogenetic pattern of prey consumption was evident, in addition to the seasonal pattern. Comparison of G. mucronatus and E. attenuata size ranges from the field and in pipefish guts revealed that S. fuscus preyed upon the smaller size classes of each species, and that mean size of prey consumed was positively related to fish size. © 1987, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Ultilization of a seagrass meadow and tidal marsh creek by blue crabs Callinectes sapidus. I. Seasonal and annual variations in abundance with emphasis on post-settlement juveniles.\n \n \n \n\n\n \n Orth, R.; and van Montfrans, J\n\n\n \n\n\n\n Marine Ecology Progress Series. 1987.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_ultilization_1987,\n\ttitle = {Ultilization of a seagrass meadow and tidal marsh creek by blue crabs {Callinectes} sapidus. {I}. {Seasonal} and annual variations in abundance with emphasis on post-settlement juveniles},\n\tdoi = {10.3354/meps041283},\n\tabstract = {ABSTRACT: Blue crabs Callinectes sapidus Rathbun were sampled in a lower Chesapeake Bay seagrass bed and adjacent tidal marsh creek from October 1982 through December 1986, using a drop net and suction sampler. Suction sampling was 88 \\% efficient and provided more accurate estimates of juvenile blue crab abundance, that were at least an order of magnitude greater than those obtained by conventional trawl gear For data analysis, C. sapidus were separated into 4 size classes by carapace width- -54.25 mm (recently settled 1st and 2nd juveniles); 4.25 to 11.00 mm (3rd through 7th juvenile crabs); {\\textbackslash}textgreater 11.00 to 525.00 mm (8th through 12th juvenile crabs); and {\\textbackslash}textgreater25.00 mm (older juveniles and adults). Seasonal and annual cycles of C. sapidus abundance were observed in both habitats with annual differences most pronounced in the grassbed. Densities of C. sapidus were significantly greater in the grassbed in all but 2 of the 48 sampling dates. Settlement of the new year class appeared to be by megalopae and occurred from August through December A pulse of small C. sapidus C4.25 mm was observed in the grassbed from early to mid-September, whereas in the marsh creek this pulse occurred 2 to 4 wk later and consisted of 3rd stage and generally larger crabs ({\\textbackslash}textgreater4.25 mm). The small numbers of 1st and 2nd stage juvenile crabs ({\\textbackslash}textless4.25 mm) in the marsh creek in contrast to their abundance in the grassbed may result from increased predation in the tidal marsh creek or selective settlement into the grassbed. C. sapidus were rare in the marsh creek in winter but densities of crabs 525 mm remained high in the grassbed from fall through early spring. Densities decreased gradually in both habitats to lowest levels by mid-August. Approximately 90 '10 or more of C. sapidus collected at both sites from late August to June were 525 mm in carapace width. Densities of individuals 11 to 25 mm and {\\textbackslash}textgreater25 mm throughout the study period did not differ significantly among years (1983 to 1986) even though there were significant differences in the abundance of smaller sized individuals between 1983-84 and 1985-86. This suggests mortality within or emigration from grassbeds around this size. A possible ontogenetic shift in habitat use by crabs 11 to 25 mm may reflect a refuge in size from predation. has},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, RJ and van Montfrans, J},\n\tyear = {1987},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n ABSTRACT: Blue crabs Callinectes sapidus Rathbun were sampled in a lower Chesapeake Bay seagrass bed and adjacent tidal marsh creek from October 1982 through December 1986, using a drop net and suction sampler. Suction sampling was 88 % efficient and provided more accurate estimates of juvenile blue crab abundance, that were at least an order of magnitude greater than those obtained by conventional trawl gear For data analysis, C. sapidus were separated into 4 size classes by carapace width- -54.25 mm (recently settled 1st and 2nd juveniles); 4.25 to 11.00 mm (3rd through 7th juvenile crabs); \\textgreater 11.00 to 525.00 mm (8th through 12th juvenile crabs); and \\textgreater25.00 mm (older juveniles and adults). Seasonal and annual cycles of C. sapidus abundance were observed in both habitats with annual differences most pronounced in the grassbed. Densities of C. sapidus were significantly greater in the grassbed in all but 2 of the 48 sampling dates. Settlement of the new year class appeared to be by megalopae and occurred from August through December A pulse of small C. sapidus C4.25 mm was observed in the grassbed from early to mid-September, whereas in the marsh creek this pulse occurred 2 to 4 wk later and consisted of 3rd stage and generally larger crabs (\\textgreater4.25 mm). The small numbers of 1st and 2nd stage juvenile crabs (\\textless4.25 mm) in the marsh creek in contrast to their abundance in the grassbed may result from increased predation in the tidal marsh creek or selective settlement into the grassbed. C. sapidus were rare in the marsh creek in winter but densities of crabs 525 mm remained high in the grassbed from fall through early spring. Densities decreased gradually in both habitats to lowest levels by mid-August. Approximately 90 '10 or more of C. sapidus collected at both sites from late August to June were 525 mm in carapace width. Densities of individuals 11 to 25 mm and \\textgreater25 mm throughout the study period did not differ significantly among years (1983 to 1986) even though there were significant differences in the abundance of smaller sized individuals between 1983-84 and 1985-86. This suggests mortality within or emigration from grassbeds around this size. A possible ontogenetic shift in habitat use by crabs 11 to 25 mm may reflect a refuge in size from predation. has\n
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\n \n\n \n \n \n \n \n Use of Microwire Tags for Tagging Juvenile Blue Crabs (Callinectes sapidus Rathbun).\n \n \n \n\n\n \n van Montfrans, J.; Capelli, J.; Orth, R. J.; and Ryer, C. H.\n\n\n \n\n\n\n Journal of Crustacean Biology. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{van_montfrans_use_1986,\n\ttitle = {Use of {Microwire} {Tags} for {Tagging} {Juvenile} {Blue} {Crabs} ({Callinectes} sapidus {Rathbun})},\n\tdoi = {10.2307/1548177},\n\tabstract = {A 51-day laboratory study was conducted to examine the effects of coded microwire tags (CWTs) injected into the basal muscle of the fifth pereiopod in 27 juvenile blue crabs, Callinectes sapidus (initial carapace width 20.8-39.3 mm). Thirty untagged crabs (initial carapace width 18.2-27.6 mm) served as a control. Mortality in tagged individuals (11\\%) did not differ significantly from that of controls (3\\%). Tag retention was 88\\% for crabs that molted at least once. All tagged crabs that molted twice and retained a tag through the first molt did so through the second molt as well. No significant difference was observed in growth increment per molt as indicated by an absolute and per cent increase in carapace width. However, a difference in growth rate as indicated by the lower number of tagged crabs that molted twice during the experiment was inferred from the data. The advantages and disadvantages of CWTs for marking juvenile blue crabs are discussed.},\n\tjournal = {Journal of Crustacean Biology},\n\tauthor = {van Montfrans, Jacques and Capelli, J. and Orth, R. J. and Ryer, C. H.},\n\tyear = {1986},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n A 51-day laboratory study was conducted to examine the effects of coded microwire tags (CWTs) injected into the basal muscle of the fifth pereiopod in 27 juvenile blue crabs, Callinectes sapidus (initial carapace width 20.8-39.3 mm). Thirty untagged crabs (initial carapace width 18.2-27.6 mm) served as a control. Mortality in tagged individuals (11%) did not differ significantly from that of controls (3%). Tag retention was 88% for crabs that molted at least once. All tagged crabs that molted twice and retained a tag through the first molt did so through the second molt as well. No significant difference was observed in growth increment per molt as indicated by an absolute and per cent increase in carapace width. However, a difference in growth rate as indicated by the lower number of tagged crabs that molted twice during the experiment was inferred from the data. The advantages and disadvantages of CWTs for marking juvenile blue crabs are discussed.\n
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\n \n\n \n \n \n \n \n Secondary Production of Gammarus mucronatus Say (Amphipoda: Gammaridae) in Warm Temperate Estuarine Habitats, York River, Virginia.\n \n \n \n\n\n \n Fredette, T. J.; and Diaz, R. J.\n\n\n \n\n\n\n Journal of Crustacean Biology. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{fredette_secondary_1986,\n\ttitle = {Secondary {Production} of {Gammarus} mucronatus {Say} ({Amphipoda}: {Gammaridae}) in {Warm} {Temperate} {Estuarine} {Habitats}, {York} {River}, {Virginia}},\n\tdoi = {10.2307/1548387},\n\tabstract = {The life history of the amphipod Gammarus mucronatus was examined in two warm temperate estuarine habitats, a sea-grass (Zostera marina) bed and the macroalgae region (Ulva spp., Enteromorpha spp.) of a fouling community. Amphipod populations were present in the sea-grass habitat during most of the entire year ranging from {\\textbackslash}textless50m2 in late summer to 1,200 m-2 in June, while the algal habitat was occupied only from late winter to early summer, with maximum abundances as high as 6,800 m2. Based on laboratory growth experiments, observations on field growth rates, and recognition of cohorts from size-frequency distributions, it is estimated that G. mucronatus is capable of producting approzimately 6-9 cohorts per year. Rapid spring and summer growth is accompanied by maturation at smaller size and reduction in brood size, egg size, and development time.},\n\tjournal = {Journal of Crustacean Biology},\n\tauthor = {Fredette, Thomas J. and Diaz, Robert J.},\n\tyear = {1986},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The life history of the amphipod Gammarus mucronatus was examined in two warm temperate estuarine habitats, a sea-grass (Zostera marina) bed and the macroalgae region (Ulva spp., Enteromorpha spp.) of a fouling community. Amphipod populations were present in the sea-grass habitat during most of the entire year ranging from \\textless50m2 in late summer to 1,200 m-2 in June, while the algal habitat was occupied only from late winter to early summer, with maximum abundances as high as 6,800 m2. Based on laboratory growth experiments, observations on field growth rates, and recognition of cohorts from size-frequency distributions, it is estimated that G. mucronatus is capable of producting approzimately 6-9 cohorts per year. Rapid spring and summer growth is accompanied by maturation at smaller size and reduction in brood size, egg size, and development time.\n
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\n \n\n \n \n \n \n \n Life History of Gammarus mucronatus Say (Amphipoda: Gammaridae) in Warm Temperate Estuarine Habitats, York River, Virginia.\n \n \n \n\n\n \n Fredette, T. J.; and Diaz, R. J.\n\n\n \n\n\n\n Journal of Crustacean Biology. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{fredette_life_1986,\n\ttitle = {Life {History} of {Gammarus} mucronatus {Say} ({Amphipoda}: {Gammaridae}) in {Warm} {Temperate} {Estuarine} {Habitats}, {York} {River}, {Virginia}},\n\tdoi = {10.2307/1547931},\n\tabstract = {Secondary production of the amphipod Gammarus mucronatus was studied in a sea-grass (Zostera marina) habitat and a macroalgal fouling community on old pier pilings. Populations of G. mucronatus were present in the macroalgal habitat during only 4 months of the year with a production of 10.2-12.9 g dry wt· m{\\textbackslash}textlesssup{\\textbackslash}textgreater-2{\\textbackslash}textless/sup{\\textbackslash}textgreater· yr{\\textbackslash}textlesssup{\\textbackslash}textgreater-1{\\textbackslash}textless/sup{\\textbackslash}textgreater compared with 5.0-6.5 g dry wt· m{\\textbackslash}textlesssup{\\textbackslash}textgreater-2{\\textbackslash}textless/sup{\\textbackslash}textgreater· yr{\\textbackslash}textlesssup{\\textbackslash}textgreater-1{\\textbackslash}textless/sup{\\textbackslash}textgreater in the sea-grass habitat, where populations were maintained throughout the year. Rapid growth to maximum size results in short cohort production intervals (CPI) with annual production to mean biomass ratios (P/B̄) ranging from 36.8-76.8. A modified instantaneous growth rate method gave production estimates that were approximately 25\\% higher than estimates using a size-frequency method. Production estimates using 4 different variations of the size-frequency method produced similar results. The sum of size-frequency estimates when males and females were considered separately results in slightly lower production values than combined calculations since dimorphic size biases are excluded. The results of this study indicate a need to evaluate carefully the productivity of tropical and warm and cool temperate habitats, since rapid growth of organisms such as amphipods could result in extremely high production estimates even where standing stock is low.},\n\tjournal = {Journal of Crustacean Biology},\n\tauthor = {Fredette, Thomas J. and Diaz, Robert J.},\n\tyear = {1986},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Secondary production of the amphipod Gammarus mucronatus was studied in a sea-grass (Zostera marina) habitat and a macroalgal fouling community on old pier pilings. Populations of G. mucronatus were present in the macroalgal habitat during only 4 months of the year with a production of 10.2-12.9 g dry wt· m\\textlesssup\\textgreater-2\\textless/sup\\textgreater· yr\\textlesssup\\textgreater-1\\textless/sup\\textgreater compared with 5.0-6.5 g dry wt· m\\textlesssup\\textgreater-2\\textless/sup\\textgreater· yr\\textlesssup\\textgreater-1\\textless/sup\\textgreater in the sea-grass habitat, where populations were maintained throughout the year. Rapid growth to maximum size results in short cohort production intervals (CPI) with annual production to mean biomass ratios (P/B̄) ranging from 36.8-76.8. A modified instantaneous growth rate method gave production estimates that were approximately 25% higher than estimates using a size-frequency method. Production estimates using 4 different variations of the size-frequency method produced similar results. The sum of size-frequency estimates when males and females were considered separately results in slightly lower production values than combined calculations since dimorphic size biases are excluded. The results of this study indicate a need to evaluate carefully the productivity of tropical and warm and cool temperate habitats, since rapid growth of organisms such as amphipods could result in extremely high production estimates even where standing stock is low.\n
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\n \n\n \n \n \n \n \n Benefit Taxation for Environmental Improvement: A Case Example from Virginia's Soft Crab Fishery.\n \n \n \n\n\n \n Shabman, L. A.; and Capps, O.\n\n\n \n\n\n\n Land Economics. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{shabman_benefit_1985,\n\ttitle = {Benefit {Taxation} for {Environmental} {Improvement}: {A} {Case} {Example} from {Virginia}'s {Soft} {Crab} {Fishery}},\n\tdoi = {10.2307/3146157},\n\tabstract = {The article focuses on benefit taxation for environmental improvement. The principle that beneficiaries of public services should bear the tax burden for their provision can be traced back at least to economist Knut Wicksell. He argued that beneficiary taxation had a political justification when government programs which might not win majority approval if paid from general revenues would be acceptable if beneficiaries bore program costs. The modem public finance literature argues that benefit taxation can promote efficiency in public decisions which determine the quantity of a government service to provide and also can serve a particular conception of fairness in the distribution of the tax burden. Demonstrating that the conditions hold for environmental enhancement programs, where benefits are widespread and difficult to appropriate, is often an analytically intractable problem. The absence of credible analysis can create an insurmountable obstacle to political implementation of benefit-tax-based revenue sources for environmental programs.},\n\tjournal = {Land Economics},\n\tauthor = {Shabman, Leonard A. and Capps, Oral},\n\tyear = {1985},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The article focuses on benefit taxation for environmental improvement. The principle that beneficiaries of public services should bear the tax burden for their provision can be traced back at least to economist Knut Wicksell. He argued that beneficiary taxation had a political justification when government programs which might not win majority approval if paid from general revenues would be acceptable if beneficiaries bore program costs. The modem public finance literature argues that benefit taxation can promote efficiency in public decisions which determine the quantity of a government service to provide and also can serve a particular conception of fairness in the distribution of the tax burden. Demonstrating that the conditions hold for environmental enhancement programs, where benefits are widespread and difficult to appropriate, is often an analytically intractable problem. The absence of credible analysis can create an insurmountable obstacle to political implementation of benefit-tax-based revenue sources for environmental programs.\n
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\n \n\n \n \n \n \n \n The effects of grazers and light penetration on the survival of transplants of Vallisneria americana Michs in the tidal Potomac River, Maryland.\n \n \n \n\n\n \n Carter, V.; and Rybicki, N. B.\n\n\n \n\n\n\n Aquatic Botany. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{carter_effects_1985,\n\ttitle = {The effects of grazers and light penetration on the survival of transplants of {Vallisneria} americana {Michs} in the tidal {Potomac} {River}, {Maryland}},\n\tdoi = {10.1016/0304-3770(85)90066-X},\n\tabstract = {Poor light penetration and grazing are among the factors potentially responsible for the lack of submersed aquatic macrophytes in the tidal Potomac River. Between 1980 and 1983, plugs, springs and tubers of Vallisneria americana Michx were transplanted from the oligohaline Potomac Estuary to six sites in the freshwater tidal Potomac River. Transplants made in 1980 and 1981 were generally successful only when protected by full exclosures which prevented grazing. Grazing resulted in the removal of whole plants or clipping off of plant leaves in unprotected plots. Plants protected in the first year were permanently established, despite the occurrence of grazing in subsequent years, at Elodea Cove and Rosier Bluff, where light penetration was high (average 1\\% light level was 1.6-1.7 m). Plants were not permanent;y established at Goose Island, where light penetration was lower (average 1\\% light level was 1.4 m) and grazing occurred, or Neabsco Bay where light penetration was very low (average 1\\% light level was 1.0 m) and grazing may not have occurred. In 1983, Secchi depth transparencies in the upper tidal river were improved significantly compared to 1978-1981. Both protected and unprotected transplants thrived in 1983. © 1985.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B.},\n\tyear = {1985},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Poor light penetration and grazing are among the factors potentially responsible for the lack of submersed aquatic macrophytes in the tidal Potomac River. Between 1980 and 1983, plugs, springs and tubers of Vallisneria americana Michx were transplanted from the oligohaline Potomac Estuary to six sites in the freshwater tidal Potomac River. Transplants made in 1980 and 1981 were generally successful only when protected by full exclosures which prevented grazing. Grazing resulted in the removal of whole plants or clipping off of plant leaves in unprotected plots. Plants protected in the first year were permanently established, despite the occurrence of grazing in subsequent years, at Elodea Cove and Rosier Bluff, where light penetration was high (average 1% light level was 1.6-1.7 m). Plants were not permanent;y established at Goose Island, where light penetration was lower (average 1% light level was 1.4 m) and grazing occurred, or Neabsco Bay where light penetration was very low (average 1% light level was 1.0 m) and grazing may not have occurred. In 1983, Secchi depth transparencies in the upper tidal river were improved significantly compared to 1978-1981. Both protected and unprotected transplants thrived in 1983. © 1985.\n
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\n \n\n \n \n \n \n \n Epiphyte-grazer relationships in seagrass meadows: Consequences for seagrass growth and production.\n \n \n \n\n\n \n van Montfrans, J.; Wetzel, R. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{van_montfrans_epiphyte-grazer_1984,\n\ttitle = {Epiphyte-grazer relationships in seagrass meadows: {Consequences} for seagrass growth and production},\n\tdoi = {10.2307/1351615},\n\tabstract = {Studies of seagrass meadows have shown that the production of algal epiphytes attached to seagrass blades approaches 20\\% of the seagrass production and that epiphytes are more important as food for associated fauna than are the more refractory seagrass blades. Since epiphytes may compete with seagrasses for light and water column nutrients, excessive epiphytic fouling could have serious consequences for seagrass growth. We summarize much of the literature on epiphytegrazer relationships in seagrass meadows within the context of seagrass growth and production. We also provide insights from mathematical modeling simulations of these relationships for a Chesapeake Bay Zostera marina meadow. Finally we focus on future research needs for more completely understanding the influences that epiphyte grazers have on seagrass production. © 1984 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {van Montfrans, Jacques and Wetzel, Richard L. and Orth, Robert J.},\n\tyear = {1984},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Studies of seagrass meadows have shown that the production of algal epiphytes attached to seagrass blades approaches 20% of the seagrass production and that epiphytes are more important as food for associated fauna than are the more refractory seagrass blades. Since epiphytes may compete with seagrasses for light and water column nutrients, excessive epiphytic fouling could have serious consequences for seagrass growth. We summarize much of the literature on epiphytegrazer relationships in seagrass meadows within the context of seagrass growth and production. We also provide insights from mathematical modeling simulations of these relationships for a Chesapeake Bay Zostera marina meadow. Finally we focus on future research needs for more completely understanding the influences that epiphyte grazers have on seagrass production. © 1984 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n The nursery role of seagrass meadows in the upper and lower reaches of the Chesapeake Bay.\n \n \n \n\n\n \n Heck, K. L.; and Thoman, T. A.\n\n\n \n\n\n\n Estuaries. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{heck_nursery_1984,\n\ttitle = {The nursery role of seagrass meadows in the upper and lower reaches of the {Chesapeake} {Bay}},\n\tdoi = {10.2307/1351958},\n\tabstract = {A two-year trawling and gill-netting study of vegetated and unvegetated bottoms near Parson's Island, Maryland and near the mouth of the York River, Virginia was carried out to assess the nursery function of submerged vegetation for populations of fishes and decapod crustaceans in the Chesapeake Bay. Results revealed that vegetated bottoms supported substantially larger numbers of decapods, but not fishes, than unvegetated substrates. The lower Bay grassbed was an important nursery area for juvenile blue crabs, although neither of the grassbeds functioned as a nursery for commercially or recreationally valuable fishes. Our results suggest that: (1) further decreases in lower Bay Seagrass biomass would result in reduced numbers of adult blue crabs, but should not substantially affect populations of valuable fish species; (2) additional decreases in Upper Bay submerged vegetation should not produce dramatic change in the population sizes of either adult blue crabs or fishes. © 1984, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Heck, Kenneth L. and Thoman, Timothy A.},\n\tyear = {1984},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n A two-year trawling and gill-netting study of vegetated and unvegetated bottoms near Parson's Island, Maryland and near the mouth of the York River, Virginia was carried out to assess the nursery function of submerged vegetation for populations of fishes and decapod crustaceans in the Chesapeake Bay. Results revealed that vegetated bottoms supported substantially larger numbers of decapods, but not fishes, than unvegetated substrates. The lower Bay grassbed was an important nursery area for juvenile blue crabs, although neither of the grassbeds functioned as a nursery for commercially or recreationally valuable fishes. Our results suggest that: (1) further decreases in lower Bay Seagrass biomass would result in reduced numbers of adult blue crabs, but should not substantially affect populations of valuable fish species; (2) additional decreases in Upper Bay submerged vegetation should not produce dramatic change in the population sizes of either adult blue crabs or fishes. © 1984, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Epiphyte-seagrass relationships with an emphasis on the role of micrograzing: A review.\n \n \n \n\n\n \n Orth, R. J.; and Van Montfrans, J.\n\n\n \n\n\n\n Aquatic Botany. 1984.\n \n\n\n\n
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@article{orth_epiphyte-seagrass_1984,\n\ttitle = {Epiphyte-seagrass relationships with an emphasis on the role of micrograzing: {A} review},\n\tdoi = {10.1016/0304-3770(84)90080-9},\n\tabstract = {Despite the recent advances in seagrass ecology over the last ten years, there are still numerous aspects of the ecological and biological interactions that occur in seagrass ecosystems that remain poorly understood. We have attempted, here, to place into perspective one interrelationship that could have important implications in the production and vigor of seagrasses. This is the relationship between epiphytic fouling by macroalgae and periphyton and the grazers which consume them as a food source while leaving the leaves intact. Our approach to this review was first to describe the relationships between macroalgae, periphyton and the seagrass host in terms of physical benefits, biochemical interactions, factors which reduce fouling on the host, and the effects of epiphytism on seagrass photosynthesis. We then examined the importance of epiphytes as a food source for those herbivores found in seagrass beds, and looked at the consequences of this grazing and removal of epiphytes for the seagrass host. Based on the potential impact of epiphytes on seagrass and grazers on epiphytes, we developed a hypothetical model that describes the effect of increasing epiphytic fouling on seagrass production in the presence and absence of grazers. From this model, we have made predictions on the direction of seagrass decline with diminishing light along depth and estuarine gradients. Lastly, we touched briefly on the problem of eutrophication and how it affects the balance of these interrelationships, and the management options to insure the health and survival of seagrass habitats in the face of increasing stress by man on these critically important ecosystems. © 1984.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Van Montfrans, Jacques},\n\tyear = {1984},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Despite the recent advances in seagrass ecology over the last ten years, there are still numerous aspects of the ecological and biological interactions that occur in seagrass ecosystems that remain poorly understood. We have attempted, here, to place into perspective one interrelationship that could have important implications in the production and vigor of seagrasses. This is the relationship between epiphytic fouling by macroalgae and periphyton and the grazers which consume them as a food source while leaving the leaves intact. Our approach to this review was first to describe the relationships between macroalgae, periphyton and the seagrass host in terms of physical benefits, biochemical interactions, factors which reduce fouling on the host, and the effects of epiphytism on seagrass photosynthesis. We then examined the importance of epiphytes as a food source for those herbivores found in seagrass beds, and looked at the consequences of this grazing and removal of epiphytes for the seagrass host. Based on the potential impact of epiphytes on seagrass and grazers on epiphytes, we developed a hypothetical model that describes the effect of increasing epiphytic fouling on seagrass production in the presence and absence of grazers. From this model, we have made predictions on the direction of seagrass decline with diminishing light along depth and estuarine gradients. Lastly, we touched briefly on the problem of eutrophication and how it affects the balance of these interrelationships, and the management options to insure the health and survival of seagrass habitats in the face of increasing stress by man on these critically important ecosystems. © 1984.\n
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\n \n\n \n \n \n \n \n Faunal communities in seagrass beds: A review of the influence of plant structure and prey characteristics on predator-prey relationships.\n \n \n \n\n\n \n Orth, R. J.; Heck, K. L.; and van Montfrans, J.\n\n\n \n\n\n\n 1984.\n Publication Title: Estuaries\n\n\n\n
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@book{orth_faunal_1984,\n\ttitle = {Faunal communities in seagrass beds: {A} review of the influence of plant structure and prey characteristics on predator-prey relationships},\n\tabstract = {When compared with nearby unvergetated areas, seagrass meadows contain a dense and strikingly rich assemblage of vertebrates and invertebrates. Most recent literature has focused on evaluating the role of predation in structuring seagrass faunal communities; however, habitat complexity, abundance of food and sediment stability may also be important. This paper summarizes studies relating predator-prey relationships to different features of the seagrass system. This review suggests that the abundance of many species, both epifauna and infauna, is positively correlated with two distinct aspects of plant morphology: 1) the root-rhizome mat, and 2) the plant canopy. A scheme was developed that defines the conditions under which any particular species will be abundant or rare in a seagrass assemblage. This scheme is based on prey and predator characteristics (e.g., epifaunal vs. infaunal, tube-dweller vs. nontube dweller, burrowers vs. nonburrowers, and large vs. small as adult) and on characteristics of the seagrasses (e.g., leaf morphology, shoot density, shoot biomass, structural complexity of the meadow, and root-rhizome density and standing crop). © 1984 Estuarine Research Federation.},\n\tauthor = {Orth, Robert J. and Heck, Kenneth L. and van Montfrans, Jacques},\n\tyear = {1984},\n\tdoi = {10.2307/1351618},\n\tnote = {Publication Title: Estuaries},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n When compared with nearby unvergetated areas, seagrass meadows contain a dense and strikingly rich assemblage of vertebrates and invertebrates. Most recent literature has focused on evaluating the role of predation in structuring seagrass faunal communities; however, habitat complexity, abundance of food and sediment stability may also be important. This paper summarizes studies relating predator-prey relationships to different features of the seagrass system. This review suggests that the abundance of many species, both epifauna and infauna, is positively correlated with two distinct aspects of plant morphology: 1) the root-rhizome mat, and 2) the plant canopy. A scheme was developed that defines the conditions under which any particular species will be abundant or rare in a seagrass assemblage. This scheme is based on prey and predator characteristics (e.g., epifaunal vs. infaunal, tube-dweller vs. nontube dweller, burrowers vs. nonburrowers, and large vs. small as adult) and on characteristics of the seagrasses (e.g., leaf morphology, shoot density, shoot biomass, structural complexity of the meadow, and root-rhizome density and standing crop). © 1984 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Feeding chronology, daily ration, and the effects of temperature upon gastric evacuation in the pipefish, Syngnathus fuscus.\n \n \n \n\n\n \n Ryer, C. H.; and Boehlert, G. W.\n\n\n \n\n\n\n Environmental Biology of Fishes. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{ryer_feeding_1983,\n\ttitle = {Feeding chronology, daily ration, and the effects of temperature upon gastric evacuation in the pipefish, {Syngnathus} fuscus},\n\tdoi = {10.1007/BF00692379},\n\tabstract = {Feeding chronology, daily ration, and the effects of temperature upon gastric evacuation were examined in the pipefish, Syngnathus fuscus, from field and laboratory data. S. fuscus displayed a pattern of diurnal feeding, characteristic of syngnathids. Daily ration calculations yielded estimates of 4.0 and 4.4\\% body weight per day, which are comparable to estimates for other teleosts. Evacuation rate was found to be temperature dependent. with more rapid evacuation with increasing temperature. In addition, evacuation rate was found to be positively correlated with gut content. Slowing of evacuation rate with decreasing gut content may allow for increased assimilation efficiency during periods of low food availability. Daily ration, although controlled by the temperature dependence of evacuation rate, may also be controlled by prey abundance; fish maximize food intake during periods of high prey availability, and maximize upon assimilation during periods of low prey availability. © 1983 Dr W. Junk Publishers.},\n\tjournal = {Environmental Biology of Fishes},\n\tauthor = {Ryer, Clifford H. and Boehlert, George W.},\n\tyear = {1983},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Feeding chronology, daily ration, and the effects of temperature upon gastric evacuation were examined in the pipefish, Syngnathus fuscus, from field and laboratory data. S. fuscus displayed a pattern of diurnal feeding, characteristic of syngnathids. Daily ration calculations yielded estimates of 4.0 and 4.4% body weight per day, which are comparable to estimates for other teleosts. Evacuation rate was found to be temperature dependent. with more rapid evacuation with increasing temperature. In addition, evacuation rate was found to be positively correlated with gut content. Slowing of evacuation rate with decreasing gut content may allow for increased assimilation efficiency during periods of low food availability. Daily ration, although controlled by the temperature dependence of evacuation rate, may also be controlled by prey abundance; fish maximize food intake during periods of high prey availability, and maximize upon assimilation during periods of low prey availability. © 1983 Dr W. Junk Publishers.\n
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\n \n\n \n \n \n \n \n Population dynamics of an estuarine-dependent fish, the spot ( Leiostomus xanthurus), along a tidal creek- seagrass meadow coenocline.\n \n \n \n\n\n \n Weinstein, M. P.\n\n\n \n\n\n\n Canadian Journal of Fisheries and Aquatic Sciences. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{weinstein_population_1983,\n\ttitle = {Population dynamics of an estuarine-dependent fish, the spot ( {Leiostomus} xanthurus), along a tidal creek- seagrass meadow coenocline.},\n\tdoi = {10.1139/f83-189},\n\tabstract = {The population was resident in the creek for up to 182 d with the average individual present for 91 d. When this population turnover rate was compared to the total population decay rate (marked plus unmarked fish), the exchange between habitats (immigration/emigration) accounted for c.26\\% of the total decay rate, with the remainder attributed to natural mortality. The estimated production in this population was 21.8 kcal (91 342 J) m-2 d-1, {\\textbackslash}textgreater6 times greater than previously reported values for this species for all size classes over the entire growing season.-from Author},\n\tjournal = {Canadian Journal of Fisheries and Aquatic Sciences},\n\tauthor = {Weinstein, M. P.},\n\tyear = {1983},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The population was resident in the creek for up to 182 d with the average individual present for 91 d. When this population turnover rate was compared to the total population decay rate (marked plus unmarked fish), the exchange between habitats (immigration/emigration) accounted for c.26% of the total decay rate, with the remainder attributed to natural mortality. The estimated production in this population was 21.8 kcal (91 342 J) m-2 d-1, \\textgreater6 times greater than previously reported values for this species for all size classes over the entire growing season.-from Author\n
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\n \n\n \n \n \n \n \n Submerged aquatic vegetation: distribution and abundance in the lower Chesapeake Bay and the interactive effects of light, epiphytes, and grazers.\n \n \n \n\n\n \n Orth, R J; Moore, K A; and Montfrans, J V\n\n\n \n\n\n\n U.S. EPA. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_submerged_1983,\n\ttitle = {Submerged aquatic vegetation: distribution and abundance in the lower {Chesapeake} {Bay} and the interactive effects of light, epiphytes, and grazers},\n\tabstract = {Submerged aquatic vegetation a major ecological resource, has undergone a major decline in Chesapeake Bay during the past decade. A literature review of the relationship between epiphytic fouling by macroalgae and periphyton and the grazers that feed on these epiphytes indicates that grazing plays a major role in preventing over-growth of epiphytes. Nutrient enrichment can stimulate the excessive growth of epiphytes, resulting in death of the plants. The salinity tolerances of one major grazer, the snail Bittium varium, were studied to determine whether rapid fresh-water influx would prove fatal to the snail. Studies of plant vigor, under three shading conditions, in the presence and absence of Bittium varium, indicated that within each shading condition plant vigor was enhanced by the presence of the snail.},\n\tjournal = {U.S. EPA},\n\tauthor = {Orth, R J and Moore, K A and Montfrans, J V},\n\tyear = {1983},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Submerged aquatic vegetation a major ecological resource, has undergone a major decline in Chesapeake Bay during the past decade. A literature review of the relationship between epiphytic fouling by macroalgae and periphyton and the grazers that feed on these epiphytes indicates that grazing plays a major role in preventing over-growth of epiphytes. Nutrient enrichment can stimulate the excessive growth of epiphytes, resulting in death of the plants. The salinity tolerances of one major grazer, the snail Bittium varium, were studied to determine whether rapid fresh-water influx would prove fatal to the snail. Studies of plant vigor, under three shading conditions, in the presence and absence of Bittium varium, indicated that within each shading condition plant vigor was enhanced by the presence of the snail.\n
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\n \n\n \n \n \n \n \n Comparative ecology of nekton residing in a tidal creek and adjacent seagrass meadow, community composition and structure.\n \n \n \n\n\n \n Weinstein, M.; and Brooks, H.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{weinstein_comparative_1983,\n\ttitle = {Comparative ecology of nekton residing in a tidal creek and adjacent seagrass meadow, community composition and structure},\n\tdoi = {10.3354/meps012015},\n\tabstract = {ABSTRACT: A structural analysis of the nekton communities occupying a tldal creek and adjacent seagrass meadow at Vaucluse Shores, Virginia (Delmawa Peninsula, USA) is presented along with a comparison of the relative value of each habit to the early life stages of marine and estuarine species. Seagrass meadows were characterized by significantly greater richness and diversity of constituent taxa; both areas, nevertheless, contained mixtures of habitat specialists and wide-ranging (ubiquitous) species that displayed no area1 preferences. Except for a few resident forms, much of the nekton community in the grassbed was comprised of less abundant 'southern' species that entered the Chesapeake Bay in late summer and fall. Reciprocal averaging and numerical classification procedures applied to pooled station collections further indicated the clinal nature of species distributions among habitats, but also clearly demonstrated several microhabitat associations for either the Zostera marina or Ruppia maritima portions of the grassbed. The sciaenid. Leiostomus xanthurus dominated the nekton in both habitats, with {\\textbackslash}textgreater 80 \\% of all individuals but were nearly 4 times as abundant in the tidal creek. Abundance distribution and length frequency analyses for this species indicated that the marsh is the preferred habitat but also that larger individuals in the population continuously 'bled off' into downstream areas. Two other species of regional importance. Callinectes sapidus and Paralichthys dentatus, also utilized both habitats extensively. Late in summer and early fall, juveniles of both species were more abundant in the grassbed, whereas earlier in the year, they were randomly dispersed. The apparently limited dependence on both the grassbed and tidal creek by the young of local taxa is strikingly different when compared to similar habitats at lower latitudes. In light of the differences established between these habitats and their utilization by different species, an attempt is made to identify potentially important determinants of community structure and relate these to the success of individual populations in both areas. Because few expenmental data are available, our presentation, by necessity is hypothetical.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Weinstein, MP and Brooks, HA},\n\tyear = {1983},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n ABSTRACT: A structural analysis of the nekton communities occupying a tldal creek and adjacent seagrass meadow at Vaucluse Shores, Virginia (Delmawa Peninsula, USA) is presented along with a comparison of the relative value of each habit to the early life stages of marine and estuarine species. Seagrass meadows were characterized by significantly greater richness and diversity of constituent taxa; both areas, nevertheless, contained mixtures of habitat specialists and wide-ranging (ubiquitous) species that displayed no area1 preferences. Except for a few resident forms, much of the nekton community in the grassbed was comprised of less abundant 'southern' species that entered the Chesapeake Bay in late summer and fall. Reciprocal averaging and numerical classification procedures applied to pooled station collections further indicated the clinal nature of species distributions among habitats, but also clearly demonstrated several microhabitat associations for either the Zostera marina or Ruppia maritima portions of the grassbed. The sciaenid. Leiostomus xanthurus dominated the nekton in both habitats, with \\textgreater 80 % of all individuals but were nearly 4 times as abundant in the tidal creek. Abundance distribution and length frequency analyses for this species indicated that the marsh is the preferred habitat but also that larger individuals in the population continuously 'bled off' into downstream areas. Two other species of regional importance. Callinectes sapidus and Paralichthys dentatus, also utilized both habitats extensively. Late in summer and early fall, juveniles of both species were more abundant in the grassbed, whereas earlier in the year, they were randomly dispersed. The apparently limited dependence on both the grassbed and tidal creek by the young of local taxa is strikingly different when compared to similar habitats at lower latitudes. In light of the differences established between these habitats and their utilization by different species, an attempt is made to identify potentially important determinants of community structure and relate these to the success of individual populations in both areas. Because few expenmental data are available, our presentation, by necessity is hypothetical.\n
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\n \n\n \n \n \n \n \n Preliminary studies of grazing by Bittium varium on eelgrass periphyton.\n \n \n \n\n\n \n Van Montfrans, J.; Orth, R. J.; and Vay, S. A.\n\n\n \n\n\n\n Aquatic Botany. 1982.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{van_montfrans_preliminary_1982,\n\ttitle = {Preliminary studies of grazing by {Bittium} varium on eelgrass periphyton},\n\tdoi = {10.1016/0304-3770(82)90087-0},\n\tabstract = {The grazing activities of Bittium varium Pfeiffer on periphyton colonizing live eelgrass (Zostera marina L.) and artificial eelgrass (polypropylene ribbon) were investigated. Quantitative measurements of grazing impact on artificial substrates were determined by periphyton pigment extraction and dry weight differences between grazed and ungrazed blades. Significant differences occurred in phaeophytin and dry weight calculations, but chlorophyll a measurements were not significantly different. This suggests that senescent diatoms constituted the bulk of the periphyton weight and were selectively removed over more actively photosynthesizing diatoms. An examination of scanning electron micrographs further elucidated the impact of grazing by Bittium varium. Some micrographs revealed that B. varium removed primarily the upper layer of the periphyton crust on both artificial substrates and living Zostera marina. The diatom Cocconeis scutellum Ehrenb. which attaches firmly to living Z. marina blades was less commonly removed than Nitzchia or Amphora. Through its grazing activities, B. varium may maintain community dominance by tightly adhering diatoms such as C. scutellum. Evidence of the complete removal of periphyton exposing the Z. marina epithelium was revealed in other micrographs. The grazing activities of Bittium varium, which removes periphyton from seagrass blades, could have important implications for the distribution and abundance of Zostera marina in the Chesapeake Bay. © 1982.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Van Montfrans, Jacques and Orth, Robert J. and Vay, Stephanie A.},\n\tyear = {1982},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The grazing activities of Bittium varium Pfeiffer on periphyton colonizing live eelgrass (Zostera marina L.) and artificial eelgrass (polypropylene ribbon) were investigated. Quantitative measurements of grazing impact on artificial substrates were determined by periphyton pigment extraction and dry weight differences between grazed and ungrazed blades. Significant differences occurred in phaeophytin and dry weight calculations, but chlorophyll a measurements were not significantly different. This suggests that senescent diatoms constituted the bulk of the periphyton weight and were selectively removed over more actively photosynthesizing diatoms. An examination of scanning electron micrographs further elucidated the impact of grazing by Bittium varium. Some micrographs revealed that B. varium removed primarily the upper layer of the periphyton crust on both artificial substrates and living Zostera marina. The diatom Cocconeis scutellum Ehrenb. which attaches firmly to living Z. marina blades was less commonly removed than Nitzchia or Amphora. Through its grazing activities, B. varium may maintain community dominance by tightly adhering diatoms such as C. scutellum. Evidence of the complete removal of periphyton exposing the Z. marina epithelium was revealed in other micrographs. The grazing activities of Bittium varium, which removes periphyton from seagrass blades, could have important implications for the distribution and abundance of Zostera marina in the Chesapeake Bay. © 1982.\n
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\n \n\n \n \n \n \n \n Structural components of eelgrass (Zostera marina) meadows in the lower Chesapeake Bay—Fishes.\n \n \n \n\n\n \n Orth, R. J.; and Heck, K. L.\n\n\n \n\n\n\n Estuaries. 1980.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_structural_1980,\n\ttitle = {Structural components of eelgrass ({Zostera} marina) meadows in the lower {Chesapeake} {Bay}—{Fishes}},\n\tdoi = {10.2307/1352083},\n\tabstract = {The structure of the fish community associated with eelgrass beds in the lower Chesapeake Bay was studied over a 14 month period. A total of 24,182 individuals in 48 species was collected by otter trawl with Leiostomus xanthurus (spot) comprising 63\\% of the collection, Syngnathus fuscus (northern pipefish) 14\\%, Anchoa mitchilli (bay anchovy) 9\\%, and Bairdiella chrysoura (silver perch) 5\\%. The density and diversity of fishes were higher in vegetated areas compared to unvegetated areas; fishes were more abundant in night collections Fish abundance and species number increased in the spring and early summer as both water temperature and eelgrass biomass increased and decreased in the fall and winter as temperature and eelgrass biomass decreased. Gill netting revealed some of the top predators in the system, especially the sandbar shark, Carcharhinus milberti. The fish community in the Chesapeake Bay was quite different from North Carolina eelgrass fish communities. Most notable was the rarity of the pinfish, Lagodon rhomboides, which may be a very important predator in the structuring of the epifaunal communities. © 1980, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Orth, Robert J. and Heck, Kenneth L.},\n\tyear = {1980},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n The structure of the fish community associated with eelgrass beds in the lower Chesapeake Bay was studied over a 14 month period. A total of 24,182 individuals in 48 species was collected by otter trawl with Leiostomus xanthurus (spot) comprising 63% of the collection, Syngnathus fuscus (northern pipefish) 14%, Anchoa mitchilli (bay anchovy) 9%, and Bairdiella chrysoura (silver perch) 5%. The density and diversity of fishes were higher in vegetated areas compared to unvegetated areas; fishes were more abundant in night collections Fish abundance and species number increased in the spring and early summer as both water temperature and eelgrass biomass increased and decreased in the fall and winter as temperature and eelgrass biomass decreased. Gill netting revealed some of the top predators in the system, especially the sandbar shark, Carcharhinus milberti. The fish community in the Chesapeake Bay was quite different from North Carolina eelgrass fish communities. Most notable was the rarity of the pinfish, Lagodon rhomboides, which may be a very important predator in the structuring of the epifaunal communities. © 1980, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n SEAGRASS HABITATS: THE ROLES OF HABITAT COMPLEXITY, COMPETITION AND PREDATION IN STRUCTURING ASSOCIATED FISH AND MOTILE MACROINVERTEBRATE ASSEMBLAGES.\n \n \n \n\n\n \n Heck, K. L.; and Orth, R. J.\n\n\n \n\n\n\n In Estuarine Perspectives. 1980.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@incollection{heck_seagrass_1980,\n\ttitle = {{SEAGRASS} {HABITATS}: {THE} {ROLES} {OF} {HABITAT} {COMPLEXITY}, {COMPETITION} {AND} {PREDATION} {IN} {STRUCTURING} {ASSOCIATED} {FISH} {AND} {MOTILE} {MACROINVERTEBRATE} {ASSEMBLAGES}},\n\tabstract = {Seagrass meadows represent a distinct habitat in shallow coastal and estuarine ecosystems. We examine the role of seagrass meadows as an important habitat for fishes and large mobile invertebrates. In particular, we emphasize the importance of the structural complexity of the vegetation and associated algal components. Based on data from a variety of geographical localities we consider how vegetation density, plant morphology and associated sessile colonial animals can influence abundance and diversity of predator and prey species in vegetated areas on both local and regional geographical scales. In so doing we generate hypotheses that lead to predictions concerning: size of populations and the amplitude of their fluctuations in vegetated habitats at different latitudes; success rate of predators using different foraging strategies in vegetation of different densities; and resultant diversity and abundance of invertebrate prey, juvenile fish and adult fish in different densities of vegetation.},\n\tbooktitle = {Estuarine {Perspectives}},\n\tauthor = {Heck, Kenneth L. and Orth, Robert J.},\n\tyear = {1980},\n\tdoi = {10.1016/b978-0-12-404060-1.50043-5},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Seagrass meadows represent a distinct habitat in shallow coastal and estuarine ecosystems. We examine the role of seagrass meadows as an important habitat for fishes and large mobile invertebrates. In particular, we emphasize the importance of the structural complexity of the vegetation and associated algal components. Based on data from a variety of geographical localities we consider how vegetation density, plant morphology and associated sessile colonial animals can influence abundance and diversity of predator and prey species in vegetated areas on both local and regional geographical scales. In so doing we generate hypotheses that lead to predictions concerning: size of populations and the amplitude of their fluctuations in vegetated habitats at different latitudes; success rate of predators using different foraging strategies in vegetation of different densities; and resultant diversity and abundance of invertebrate prey, juvenile fish and adult fish in different densities of vegetation.\n
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\n \n\n \n \n \n \n \n Structural components of eelgrass (Zostera marina) meadows in the lower Chesapeake Bay—Decapod crustacea.\n \n \n \n\n\n \n Heck, K. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1980.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{heck_structural_1980,\n\ttitle = {Structural components of eelgrass ({Zostera} marina) meadows in the lower {Chesapeake} {Bay}—{Decapod} crustacea},\n\tdoi = {10.2307/1352084},\n\tabstract = {Otter trawl collections of eelgrass habitats in the lower Chesapeake Bay during 1976–1977 produced 14 species of decapod crustaceans. These collections were dominated by palaemonid shrimp (Palaemonetes spp.), blue crabs (Callinectes sapidus), and sand shrimp (Crangon septemspinosa), each of which exhibited unimodal seasonal abundance curves with large summer peaks. Decapod abundance was positively correlated with plant biomass throughout the year. Decapod densities on vegetated bottoms were greater than on unvegetated bottoms, and nighttime abundance on each bottom type was greater than corresponding daytime abundance. Total decapod abundances in Chesapeake Bay eelgrass meadows appear to be much greater than those reported in North Carolina eelgrass or Gulf of Mexico turtlegrass habitats. © 1980, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Heck, K. L. and Orth, R. J.},\n\tyear = {1980},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Otter trawl collections of eelgrass habitats in the lower Chesapeake Bay during 1976–1977 produced 14 species of decapod crustaceans. These collections were dominated by palaemonid shrimp (Palaemonetes spp.), blue crabs (Callinectes sapidus), and sand shrimp (Crangon septemspinosa), each of which exhibited unimodal seasonal abundance curves with large summer peaks. Decapod abundance was positively correlated with plant biomass throughout the year. Decapod densities on vegetated bottoms were greater than on unvegetated bottoms, and nighttime abundance on each bottom type was greater than corresponding daytime abundance. Total decapod abundances in Chesapeake Bay eelgrass meadows appear to be much greater than those reported in North Carolina eelgrass or Gulf of Mexico turtlegrass habitats. © 1980, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Ecology of the gastropod epifauna of eelgrass in a Virginia estuary.\n \n \n \n\n\n \n Marsh, G. A.\n\n\n \n\n\n\n Chesapeake Science. 1976.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{marsh_ecology_1976,\n\ttitle = {Ecology of the gastropod epifauna of eelgrass in a {Virginia} estuary},\n\tdoi = {10.2307/1351196},\n\tabstract = {Twenty-three species of gastropod molluscs, including 10 prosobranchs and 13 opisthobranchs, were collected during a 14-month period from Zostera in the lower York River, Virginia. Salinities ranged from 16.0 to 22.4 ‰ during the sampling period; temperatures ranged from 2.8 to 28.3 C. Seasonal abundance, depth distribution, and notes on the life cycles and general ecology of this epifauna are reported. Diastoma varium and Crepidula convexa occurred throughout the year and were the two most abundant species collected. © 1976, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Marsh, G. Alex},\n\tyear = {1976},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Twenty-three species of gastropod molluscs, including 10 prosobranchs and 13 opisthobranchs, were collected during a 14-month period from Zostera in the lower York River, Virginia. Salinities ranged from 16.0 to 22.4 ‰ during the sampling period; temperatures ranged from 2.8 to 28.3 C. Seasonal abundance, depth distribution, and notes on the life cycles and general ecology of this epifauna are reported. Diastoma varium and Crepidula convexa occurred throughout the year and were the two most abundant species collected. © 1976, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Destruction of eelgrass, Zostera marina, by the cownose ray, Rhinoptera bonasus, in the Chesapeake Bay.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Chesapeake Science. 1975.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_destruction_1975,\n\ttitle = {Destruction of eelgrass, {Zostera} marina, by the cownose ray, {Rhinoptera} bonasus, in the {Chesapeake} {Bay}},\n\tdoi = {10.2307/1350896},\n\tabstract = {Destruction of Zostera beds in the York River, Virginia, is attributed to the digging activities of the cownose ray, Rhinoptera bonasus. The physically stable Zostera habitat with high faunal diversity and density was replaced by an unstable sand habitat with low faunal diversity and density. © 1975 Estuarine Research Federation.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Orth, Robert J.},\n\tyear = {1975},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n Destruction of Zostera beds in the York River, Virginia, is attributed to the digging activities of the cownose ray, Rhinoptera bonasus. The physically stable Zostera habitat with high faunal diversity and density was replaced by an unstable sand habitat with low faunal diversity and density. © 1975 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Benthic infauna of eelgrass, Zostera marina, beds.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Chesapeake Science. 1973.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_benthic_1973,\n\ttitle = {Benthic infauna of eelgrass, {Zostera} marina, beds},\n\tdoi = {10.2307/1350754},\n\tabstract = {The infauna of Zostera beds in the Chesapeake Bay-York River estuary and Chincoteague Bay was sampled in March and July 1970 using a corer. Sediments were fine sand or very fine sand. Sorting of sediments varied from poorly sorted to moderately well-sorted and appeared to be positively correlated with the density of Zostera at the respective stations. A total of 117 macroinvertebrate taxa was collected. Species number decreased both up the estuary and seasonally from March to July. Movement of epifaunal species from the sediments where they occur in winter months when Zostera is scarce, to the leaves in summer accounted partly for this seasonal difference. This seasonal decrease was not noted at the station farthest up-estuary where Zostera was scarce all year. Faunal similarity of the areas sampled, as measured by three indices, indicates that the infauna of most Zostera beds in the Chespeake Bay area is similar, except at the up-estuary limits of Zostera distribution. Macrofaunal density was higher than that of any other benthic habitat in the Chesapeake Bay. © 1973 Estuarine Research Federation.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Orth, Robert J.},\n\tyear = {1973},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The infauna of Zostera beds in the Chesapeake Bay-York River estuary and Chincoteague Bay was sampled in March and July 1970 using a corer. Sediments were fine sand or very fine sand. Sorting of sediments varied from poorly sorted to moderately well-sorted and appeared to be positively correlated with the density of Zostera at the respective stations. A total of 117 macroinvertebrate taxa was collected. Species number decreased both up the estuary and seasonally from March to July. Movement of epifaunal species from the sediments where they occur in winter months when Zostera is scarce, to the leaves in summer accounted partly for this seasonal difference. This seasonal decrease was not noted at the station farthest up-estuary where Zostera was scarce all year. Faunal similarity of the areas sampled, as measured by three indices, indicates that the infauna of most Zostera beds in the Chespeake Bay area is similar, except at the up-estuary limits of Zostera distribution. Macrofaunal density was higher than that of any other benthic habitat in the Chesapeake Bay. © 1973 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n The Zostera epifaunal community in the York River, Virginia.\n \n \n \n\n\n \n Marsh, G. A.\n\n\n \n\n\n\n Chesapeake Science. 1973.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{marsh_zostera_1973,\n\ttitle = {The {Zostera} epifaunal community in the {York} {River}, {Virginia}},\n\tdoi = {10.2307/1350873},\n\tabstract = {The invertebrate epifauna occurring on Zostera marina L. in the lower York River, Virginia, was sampled with the aid of SCUBA for 14 consecutive months. A collecting station was located at each of three different water depths within a single eelgrass bed. A total of 112 invertebrate species was collected. The five most abundant non-colonial species (Bittium varium, Paracerceis caudata, Crepidula convexa, Ampithoe longimana and Erichsonella attenuata) accounted for approximately 59\\% of the total fauna. These species dominated the epifauna throughout most of the year. Several other species, including Balanus improvisus, Molgula manhattensis, Polydora ligni and Ercolania fuscata, were abundant for only brief periods. A relatively high average index of affinity (58\\%) between all synchronous sample pairs indicated a generally homogeneous fauna, although several species were differentially distributed with depth. Exfoliation of Zostera after June caused a steady decline in plant biomass, but the abundance of epifauna continued to increase into the summer and fall. Lowest total numbers and species counts occurred in February and early March. Diversity values (H′) ranged from 1.92 to 3.90 bits/individual and averaged 3.04 bits/individual for all stations. High species numbers in summer were generally counteracted by relatively low equitabilities (ϵ), with H′ showing little seasonal change. The primary sources of nutrition for the epifauna appeared to be 1) plankton and suspended particulate matter, 2) detritus and microorganisms on the plant blades, and 3) epiphytic algae. © 1973 Estuarine Research Federation.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Marsh, G. Alex},\n\tyear = {1973},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n The invertebrate epifauna occurring on Zostera marina L. in the lower York River, Virginia, was sampled with the aid of SCUBA for 14 consecutive months. A collecting station was located at each of three different water depths within a single eelgrass bed. A total of 112 invertebrate species was collected. The five most abundant non-colonial species (Bittium varium, Paracerceis caudata, Crepidula convexa, Ampithoe longimana and Erichsonella attenuata) accounted for approximately 59% of the total fauna. These species dominated the epifauna throughout most of the year. Several other species, including Balanus improvisus, Molgula manhattensis, Polydora ligni and Ercolania fuscata, were abundant for only brief periods. A relatively high average index of affinity (58%) between all synchronous sample pairs indicated a generally homogeneous fauna, although several species were differentially distributed with depth. Exfoliation of Zostera after June caused a steady decline in plant biomass, but the abundance of epifauna continued to increase into the summer and fall. Lowest total numbers and species counts occurred in February and early March. Diversity values (H′) ranged from 1.92 to 3.90 bits/individual and averaged 3.04 bits/individual for all stations. High species numbers in summer were generally counteracted by relatively low equitabilities (ϵ), with H′ showing little seasonal change. The primary sources of nutrition for the epifauna appeared to be 1) plankton and suspended particulate matter, 2) detritus and microorganisms on the plant blades, and 3) epiphytic algae. © 1973 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Fishes of isle of wight and Assawoman bays near Ocean City, Maryland.\n \n \n \n\n\n \n Schwartz, F. J.\n\n\n \n\n\n\n Chesapeake Science. 1964.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{schwartz_fishes_1964,\n\ttitle = {Fishes of isle of wight and {Assawoman} bays near {Ocean} {City}, {Maryland}},\n\tdoi = {10.2307/1350562},\n\tabstract = {The occurrence of 104 species of fish belonging to 54 families and 87 genera in the Isle of Wight and Assawoman Bays near Ocean City, Maryland, is reported. These fish were collected in 1959, 1961, 1962, and 1963 by various gear. Each species is accompanied by some ecological notes pertaining to seasonal oscillations of species and populations, patterns of distribution in the bays, etc. © 1964, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Schwartz, Frank J.},\n\tyear = {1964},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
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\n The occurrence of 104 species of fish belonging to 54 families and 87 genera in the Isle of Wight and Assawoman Bays near Ocean City, Maryland, is reported. These fish were collected in 1959, 1961, 1962, and 1963 by various gear. Each species is accompanied by some ecological notes pertaining to seasonal oscillations of species and populations, patterns of distribution in the bays, etc. © 1964, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n The black duck in the Chesapeake Bay of Maryland: Breeding behavior and biology.\n \n \n \n\n\n \n Stotts, V. D.; and Davis, D. E.\n\n\n \n\n\n\n Chesapeake Science. 1960.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{stotts_black_1960,\n\ttitle = {The black duck in the {Chesapeake} {Bay} of {Maryland}: {Breeding} behavior and biology},\n\tdoi = {10.2307/1350392},\n\tabstract = {The breeding behavior and biology of black ducks, Anas rubripes, were observed from 1953–1958 on the upper Eastern Shore of Chesapeake Bay in Maryland. Ducks were trapped, banded and marked during the study in an essentially estuarine habitat, which was frost-free from mid-April to early November. The general habitat adjoining the Bay consisted of cultivated fields, pine woods with dense underbrush, extensive marshes in some areas, and duck blinds. Resident black ducks began to pair in the late summer and reached a peak in early April just before the height of the breeding season. Few if any young were observed to pair in the early fall. In the spring the male defended a territory for each clutch, generally using some promontory along the shore. The male remained nearby while the female built her nest, gradually deserting his mate during incubation. Eventually the pairing bond disappeared, although some males probably paired again with renesting hens. Females renested one or more times when the eggs were destroyed or even when the ducklings disappeared on the first day after hatching. At least eight out of 51 marked ducks were known to have renested. The dates of first laying varied from March 9 to March 27. The nesting peaks occurred about April 20. The first hatching occurred in early April; the last in early August. The date by which 50 percent of the nests were started was significantly earlier in 1953 than in 1957 or 1958 but no other differences were significant. Comparison of the peaks of hatching and of laying showed that in 1958 a loss of early clutches occurred. Nests were built most extensively in woods, less so in fields and marshes and markedly on duck blinds. They were constructed from adjacent material (leaves, grass, twigs, pine needles) in shallow basins, which were occasionally used by renesting females. Usually the nest site was covered by honeysuckle, poison ivy, brush, or grasses. Spacing between nests was determined by available cover; sometimes they were placed within a few feet of each other. The density varied from 0.6 to 15.2 nests per acre. The average number of eggs in a clutch declined from 10.9 to 7.5 during the season (360 clutches). Young females laid smaller average clutches (9.2) than adults (9.7). Primary clutches were larger (9.1) than secondary clutches (8.1) for the same females. The incubation period averaged 26.2 days (51 clutches). Neither size of clutch nor season had a significant effect on incubation period. About 5.6 percent of the eggs did not hatch. The fate of nesting was determined for 574 nests. During the six years, 38.0 percent hatched at least one egg, 11.5 percent were abandoned, and 50.0 percent were destroyed (34.0 percent by crows). Although complete and incomplete clutches were equally susceptible to predation, over half (51.8 percent) of the destruction of complete clutches occurred in the first week of incubation. An average of 9.6 percent of eggs in successful clutches was taken by crows. Estimations of production indicated that 100 females would raise 510 young to flying age and that the population in the area would decline if the mortality rate of females from flying age to breeding exceeded 78 percent. © 1960, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Stotts, Vernon D. and Davis, David E.},\n\tyear = {1960},\n\tkeywords = {Animal Interactions},\n}\n\n
\n
\n\n\n
\n The breeding behavior and biology of black ducks, Anas rubripes, were observed from 1953–1958 on the upper Eastern Shore of Chesapeake Bay in Maryland. Ducks were trapped, banded and marked during the study in an essentially estuarine habitat, which was frost-free from mid-April to early November. The general habitat adjoining the Bay consisted of cultivated fields, pine woods with dense underbrush, extensive marshes in some areas, and duck blinds. Resident black ducks began to pair in the late summer and reached a peak in early April just before the height of the breeding season. Few if any young were observed to pair in the early fall. In the spring the male defended a territory for each clutch, generally using some promontory along the shore. The male remained nearby while the female built her nest, gradually deserting his mate during incubation. Eventually the pairing bond disappeared, although some males probably paired again with renesting hens. Females renested one or more times when the eggs were destroyed or even when the ducklings disappeared on the first day after hatching. At least eight out of 51 marked ducks were known to have renested. The dates of first laying varied from March 9 to March 27. The nesting peaks occurred about April 20. The first hatching occurred in early April; the last in early August. The date by which 50 percent of the nests were started was significantly earlier in 1953 than in 1957 or 1958 but no other differences were significant. Comparison of the peaks of hatching and of laying showed that in 1958 a loss of early clutches occurred. Nests were built most extensively in woods, less so in fields and marshes and markedly on duck blinds. They were constructed from adjacent material (leaves, grass, twigs, pine needles) in shallow basins, which were occasionally used by renesting females. Usually the nest site was covered by honeysuckle, poison ivy, brush, or grasses. Spacing between nests was determined by available cover; sometimes they were placed within a few feet of each other. The density varied from 0.6 to 15.2 nests per acre. The average number of eggs in a clutch declined from 10.9 to 7.5 during the season (360 clutches). Young females laid smaller average clutches (9.2) than adults (9.7). Primary clutches were larger (9.1) than secondary clutches (8.1) for the same females. The incubation period averaged 26.2 days (51 clutches). Neither size of clutch nor season had a significant effect on incubation period. About 5.6 percent of the eggs did not hatch. The fate of nesting was determined for 574 nests. During the six years, 38.0 percent hatched at least one egg, 11.5 percent were abandoned, and 50.0 percent were destroyed (34.0 percent by crows). Although complete and incomplete clutches were equally susceptible to predation, over half (51.8 percent) of the destruction of complete clutches occurred in the first week of incubation. An average of 9.6 percent of eggs in successful clutches was taken by crows. Estimations of production indicated that 100 females would raise 510 young to flying age and that the population in the area would decline if the mortality rate of females from flying age to breeding exceeded 78 percent. © 1960, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Food of Game Ducks in the United States and Canda.\n \n \n \n\n\n \n Martin, A.; and Uhler, F.\n\n\n \n\n\n\n Technical Report 1939.\n ISBN: 3663537137 Publication Title: United States Department of Agriculture\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@techreport{martin_food_1939,\n\ttitle = {Food of {Game} {Ducks} in the {United} {States} and {Canda}},\n\tabstract = {This is a reproduction of a library book that was digitized by Google as part of an ongoing effort to preserve the information in books and make it universally accessible. http://books.google.com},\n\tauthor = {Martin, A.C. and Uhler, F.M.},\n\tyear = {1939},\n\tdoi = {10.1016/0003-6870(73)90259-7},\n\tnote = {ISBN: 3663537137\nPublication Title: United States Department of Agriculture},\n\tkeywords = {Animal Interactions},\n}\n\n
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\n This is a reproduction of a library book that was digitized by Google as part of an ongoing effort to preserve the information in books and make it universally accessible. http://books.google.com\n
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\n  \n Coastal Bays (Maryland and Virginia)\n \n \n (55)\n \n \n
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\n \n\n \n \n \n \n \n \n Actively restored ecosystems as a refuge for biological diversity: A case study from eelgrass (Zostera marina L.) - Abstract - Europe PMC.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"ActivelyPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_actively_nodate,\n\ttitle = {Actively restored ecosystems as a refuge for biological diversity: {A} case study from eelgrass ({Zostera} marina {L}.) - {Abstract} - {Europe} {PMC}},\n\turl = {https://europepmc.org/article/ppr/ppr96437},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Predator–prey interactions in a restored eelgrass ecosystem: strategies for maximizing success of reintroduced bay scallops (Argopecten irradians) - Schmitt - 2016 - Restoration Ecology - Wiley Online Library.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"Predator–preyPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_predatorprey_nodate,\n\ttitle = {Predator–prey interactions in a restored eelgrass ecosystem: strategies for maximizing success of reintroduced bay scallops ({Argopecten} irradians) - {Schmitt} - 2016 - {Restoration} {Ecology} - {Wiley} {Online} {Library}},\n\turl = {https://onlinelibrary.wiley.com/doi/full/10.1111/rec.12353},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Genetic Diversity Enhances Restoration Success by Augmenting Ecosystem Services.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"GeneticPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_genetic_nodate,\n\ttitle = {Genetic {Diversity} {Enhances} {Restoration} {Success} by {Augmenting} {Ecosystem} {Services}},\n\turl = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3382623/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n SAV in Chesapeake Bay - 2010 SAV Report.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SAVPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_sav_nodate-4,\n\ttitle = {{SAV} in {Chesapeake} {Bay} - 2010 {SAV} {Report}},\n\turl = {http://web.vims.edu/bio/sav/sav10/index.html},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n SAV in Chesapeake Bay - 2009 SAV Preliminary Information.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SAVPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_sav_nodate-3,\n\ttitle = {{SAV} in {Chesapeake} {Bay} - 2009 {SAV} {Preliminary} {Information}},\n\turl = {http://web.vims.edu/bio/sav/sav09/index.html},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n SAV in Chesapeake Bay - 2008 SAV Report.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SAVPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_sav_nodate-2,\n\ttitle = {{SAV} in {Chesapeake} {Bay} - 2008 {SAV} {Report}},\n\turl = {http://web.vims.edu/bio/sav/sav08/?svr=www},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n SAV in Chesapeake Bay - 2007 SAV Report.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SAVPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_sav_nodate-1,\n\ttitle = {{SAV} in {Chesapeake} {Bay} - 2007 {SAV} {Report}},\n\turl = {http://web.vims.edu/bio/sav/sav07/index.html},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n SAV in Chesapeake Bay - Monitoring - 2006 Report.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SAVPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_sav_nodate,\n\ttitle = {{SAV} in {Chesapeake} {Bay} - {Monitoring} - 2006 {Report}},\n\turl = {http://web.vims.edu/bio/sav/sav06/index.html},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 2005.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_submerged_nodate,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 2005},\n\turl = {http://web.vims.edu/bio/sav/sav05/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 2004.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_submerged_nodate-5,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 2004},\n\turl = {http://web.vims.edu/bio/sav/sav04/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 2003.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_submerged_nodate-4,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 2003},\n\turl = {http://web.vims.edu/bio/sav/sav03/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 2002.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_submerged_nodate-3,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 2002},\n\turl = {http://web.vims.edu/bio/sav/sav02/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 2001.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_submerged_nodate-2,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 2001},\n\turl = {http://web.vims.edu/bio/sav/sav01/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 2000.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_submerged_nodate-1,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 2000},\n\turl = {http://web.vims.edu/bio/sav/sav00/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n Submerged Aquatic Vegetation in the Chesapeake Bay for 1999.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"SubmergedPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_submerged_nodate,\n\ttitle = {Submerged {Aquatic} {Vegetation} in the {Chesapeake} {Bay} for 1999},\n\turl = {http://web.vims.edu/bio/sav/sav99/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n 1998 SAV Distribution, Contents.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"1998Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_1998_nodate,\n\ttitle = {1998 {SAV} {Distribution}, {Contents}},\n\turl = {http://web.vims.edu/bio/sav/sav98/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n 1997 SAV Distribution, Contents.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"1997Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_1997_nodate,\n\ttitle = {1997 {SAV} {Distribution}, {Contents}},\n\turl = {http://web.vims.edu/bio/sav/sav97/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n 1996 SAV Distribution, Contents.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"1996Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_1996_nodate,\n\ttitle = {1996 {SAV} {Distribution}, {Contents}},\n\turl = {http://web.vims.edu/bio/sav/sav96/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n 1995 SAV Distribution, Contents.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"1995Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_1995_nodate,\n\ttitle = {1995 {SAV} {Distribution}, {Contents}},\n\turl = {http://web.vims.edu/bio/sav/sav95/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n \n 1994 SAV Distribution, Contents.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n \n\n\n\n
\n\n\n\n \n \n \"1994Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_1994_nodate,\n\ttitle = {1994 {SAV} {Distribution}, {Contents}},\n\turl = {http://web.vims.edu/bio/sav/sav94/},\n\turldate = {2020-05-15},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
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\n \n\n \n \n \n \n \n CHESAPEAKEBAYANDPR BIITAR AND CH NCOTEAGUE BAY - 1986.\n \n \n \n\n\n \n Orth, R.; Simons, J.; Carter, V.; and Hodges, S.\n\n\n \n\n\n\n ,192. .\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_chesapeakebayandpr_nodate,\n\ttitle = {{CHESAPEAKEBAYANDPR} {BIITAR} {AND} {CH} {NCOTEAGUE} {BAY} - 1986},\n\tlanguage = {en},\n\tauthor = {Orth, Robert and Simons, Jim and Carter, Virginia and Hodges, Stephen},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {192},\n}\n\n
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\n \n\n \n \n \n \n \n \n The bay scallop (Argopecten irradians) industry collapse in Virginia and its implications for the successful management of scallop-seagrass habitats.\n \n \n \n \n\n\n \n Oreska, M. P. J.; Truitt, B.; Orth, R. J.; and Luckenbach, M. W.\n\n\n \n\n\n\n Marine Policy, 75: 116–124. January 2017.\n \n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{oreska_bay_2017,\n\ttitle = {The bay scallop ({Argopecten} irradians) industry collapse in {Virginia} and its implications for the successful management of scallop-seagrass habitats},\n\tvolume = {75},\n\tissn = {0308-597X},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0308597X16303529},\n\tdoi = {10.1016/j.marpol.2016.10.021},\n\tabstract = {Virginia supported the most productive bay scallop (Argopecten irradians) fishery in the United States in 1930, but the fishery disappeared three years later and never recovered. This collapse highlights a tipping point, but managers of extant bay scallop fisheries have not looked to this case for guidance, because the collapse has long been attributed to an exogenous eelgrass (Zostera marina) ‘wasting disease’ pandemic. Consequently, it remains little understood. However, efforts to restore the fishery, following successful eelgrass restoration, now warrant a thorough examination of its economic significance and disappearance. This study comprehensively surveyed information on the original fishery and reconstructed the pre-collapse population to evaluate restoration prospects and management strategies that reduce the risk of future scallop-seagrass system collapses. Harvest records suggest that overharvesting possibly contributed to the Virginia fishery disappearance—a factor that influenced other bay scallop fisheries but did not alarm contemporary managers in Virginia. The harvest peaked before managers observed eelgrass disappearing and exceeded most pre-collapse population estimates. Intensive dredging possibly precipitated a feedback that reduced scallop recruitment by lowering seagrass shoot densities. Managers should, therefore, consider a potential tradeoff between future scallop harvest and eelgrass restoration goals. The restored wild scallop population in Virginia cannot yet support a commercial fishery at historic levels, which removed between 270 and 380x as many individuals. However, the economic risks associated with reestablishing this fishery are low. The collapse did not cause a significant loss in total economic value, because harvesters rapidly shifted focus to clams, supplanting lost scallop revenue.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Policy},\n\tauthor = {Oreska, Matthew P. J. and Truitt, Barry and Orth, Robert J. and Luckenbach, Mark W.},\n\tmonth = jan,\n\tyear = {2017},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {116--124},\n}\n\n
\n
\n\n\n
\n Virginia supported the most productive bay scallop (Argopecten irradians) fishery in the United States in 1930, but the fishery disappeared three years later and never recovered. This collapse highlights a tipping point, but managers of extant bay scallop fisheries have not looked to this case for guidance, because the collapse has long been attributed to an exogenous eelgrass (Zostera marina) ‘wasting disease’ pandemic. Consequently, it remains little understood. However, efforts to restore the fishery, following successful eelgrass restoration, now warrant a thorough examination of its economic significance and disappearance. This study comprehensively surveyed information on the original fishery and reconstructed the pre-collapse population to evaluate restoration prospects and management strategies that reduce the risk of future scallop-seagrass system collapses. Harvest records suggest that overharvesting possibly contributed to the Virginia fishery disappearance—a factor that influenced other bay scallop fisheries but did not alarm contemporary managers in Virginia. The harvest peaked before managers observed eelgrass disappearing and exceeded most pre-collapse population estimates. Intensive dredging possibly precipitated a feedback that reduced scallop recruitment by lowering seagrass shoot densities. Managers should, therefore, consider a potential tradeoff between future scallop harvest and eelgrass restoration goals. The restored wild scallop population in Virginia cannot yet support a commercial fishery at historic levels, which removed between 270 and 380x as many individuals. However, the economic risks associated with reestablishing this fishery are low. The collapse did not cause a significant loss in total economic value, because harvesters rapidly shifted focus to clams, supplanting lost scallop revenue.\n
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\n \n\n \n \n \n \n \n \n Ecosystem services returned through seagrass restoration.\n \n \n \n \n\n\n \n Reynolds, L. K.; Waycott, M.; McGlathery, K. J.; and Orth, R. J.\n\n\n \n\n\n\n Restoration Ecology, 24(5): 583–588. 2016.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/rec.12360\n\n\n\n
\n\n\n\n \n \n \"EcosystemPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{reynolds_ecosystem_2016,\n\ttitle = {Ecosystem services returned through seagrass restoration},\n\tvolume = {24},\n\tcopyright = {© 2016 Society for Ecological Restoration},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.12360},\n\tdoi = {10.1111/rec.12360},\n\tabstract = {Ecosystem restoration is often costly, but can be effective at increasing biodiversity and ecosystem services. We used a case study—reseeding seagrass to a coastal lagoon—to demonstrate the value of enhanced ecosystem services as a result of restoration. We modeled the recovery of areal plant coverage in a system where seagrasses were lost due to disease and disturbance, and estimated the value of the returned functions of nitrogen removal and carbon sequestration. We estimated, as of 2010, that this restoration removes 170 ton of nitrogen per year via denitrificiation and sequesters carbon at a rate of 630 tons carbon per year in the sediment. Further, we estimated that natural recovery would take more than 100 years to reach the areal coverage achieved by restoration using seeds in just 10 years. Restoration enhanced this recovery, and the earlier establishment of plants results in a net gain of at least 4,100 ton of nitrogen removed from the system via denitrification and 15,000 ton of carbon sequestered in the sediment. These services have significant ecological and societal value.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2020-05-15},\n\tjournal = {Restoration Ecology},\n\tauthor = {Reynolds, Laura K. and Waycott, Michelle and McGlathery, Karen J. and Orth, Robert J.},\n\tyear = {2016},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/rec.12360},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {583--588},\n}\n\n
\n
\n\n\n
\n Ecosystem restoration is often costly, but can be effective at increasing biodiversity and ecosystem services. We used a case study—reseeding seagrass to a coastal lagoon—to demonstrate the value of enhanced ecosystem services as a result of restoration. We modeled the recovery of areal plant coverage in a system where seagrasses were lost due to disease and disturbance, and estimated the value of the returned functions of nitrogen removal and carbon sequestration. We estimated, as of 2010, that this restoration removes 170 ton of nitrogen per year via denitrificiation and sequesters carbon at a rate of 630 tons carbon per year in the sediment. Further, we estimated that natural recovery would take more than 100 years to reach the areal coverage achieved by restoration using seeds in just 10 years. Restoration enhanced this recovery, and the earlier establishment of plants results in a net gain of at least 4,100 ton of nitrogen removed from the system via denitrification and 15,000 ton of carbon sequestered in the sediment. These services have significant ecological and societal value.\n
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\n \n\n \n \n \n \n \n \n Sources of sediment carbon sequestered in restored seagrass meadows.\n \n \n \n \n\n\n \n Greiner, J. T.; Wilkinson, G. M.; McGlathery, K. J.; and Emery, K. A.\n\n\n \n\n\n\n Marine Ecology Progress Series, 551: 95–105. June 2016.\n \n\n\n\n
\n\n\n\n \n \n \"SourcesPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{greiner_sources_2016,\n\ttitle = {Sources of sediment carbon sequestered in restored seagrass meadows},\n\tvolume = {551},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v551/p95-105/},\n\tdoi = {10.3354/meps11722},\n\tabstract = {Seagrass meadows accumulate carbon in sediments as a result of in situ production and sedimentation of particulate organic matter (OM). We quantified the contribution of OM sources to the sediment carbon pool in restored seagrass meadows of different ages (unvegetated  and 4 and 10 yr since restoration) in the Virginia coastal bays. Using carbon (C) and nitrogen (N) stable isotopes, we estimated the contribution of seagrass (Zostera marina), benthic diatoms and sestonic particles (BD/S), and macroalgae (MA) to the sediment OM pool influenced by restoration (top 10 cm) with a Bayesian mixing model. Marsh grass was not a likely source based on C:N ratios of the sediment OM. The 4 and 10 yr seagrass meadows had similar OM source contributions to the top 10 cm of sediment, which were distinct from those of unvegetated sites. Seagrass, BD/S, and MA contributed 41, 56, and 3\\%, respectively, in the 10 yr age treatments and 50, 46, and 4\\%, respectively, in the 4 yr age treatments. Diagenesis of OM sources had little impact on the source contribution estimates. In combination with carbon accumulation rates at these sites (37 g C m-2 yr-1), these results indicate that 10 yr after seeding, restored seagrass meadows accumulated seagrass carbon at a rate of 14.3 g C m-2 yr-1 and non-seagrass carbon (BD/S and MA) at a rate of 22.4 g C m-2 yr-1. This study demonstrates how seagrass restoration contributes to the sequestration of ‘blue carbon’ and quantifies the impact restored seagrass meadow age has on stored sediment carbon.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Greiner, J. T. and Wilkinson, G. M. and McGlathery, K. J. and Emery, K. A.},\n\tmonth = jun,\n\tyear = {2016},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {95--105},\n}\n\n
\n
\n\n\n
\n Seagrass meadows accumulate carbon in sediments as a result of in situ production and sedimentation of particulate organic matter (OM). We quantified the contribution of OM sources to the sediment carbon pool in restored seagrass meadows of different ages (unvegetated  and 4 and 10 yr since restoration) in the Virginia coastal bays. Using carbon (C) and nitrogen (N) stable isotopes, we estimated the contribution of seagrass (Zostera marina), benthic diatoms and sestonic particles (BD/S), and macroalgae (MA) to the sediment OM pool influenced by restoration (top 10 cm) with a Bayesian mixing model. Marsh grass was not a likely source based on C:N ratios of the sediment OM. The 4 and 10 yr seagrass meadows had similar OM source contributions to the top 10 cm of sediment, which were distinct from those of unvegetated sites. Seagrass, BD/S, and MA contributed 41, 56, and 3%, respectively, in the 10 yr age treatments and 50, 46, and 4%, respectively, in the 4 yr age treatments. Diagenesis of OM sources had little impact on the source contribution estimates. In combination with carbon accumulation rates at these sites (37 g C m-2 yr-1), these results indicate that 10 yr after seeding, restored seagrass meadows accumulated seagrass carbon at a rate of 14.3 g C m-2 yr-1 and non-seagrass carbon (BD/S and MA) at a rate of 22.4 g C m-2 yr-1. This study demonstrates how seagrass restoration contributes to the sequestration of ‘blue carbon’ and quantifies the impact restored seagrass meadow age has on stored sediment carbon.\n
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\n \n\n \n \n \n \n \n \n Roles of dispersal and predation in determining seedling recruitment patterns in a foundational marine angiosperm.\n \n \n \n \n\n\n \n Manley, S. R.; Orth, R. J.; and Ruiz-Montoya, L.\n\n\n \n\n\n\n Marine Ecology Progress Series, 533: 109–120. August 2015.\n \n\n\n\n
\n\n\n\n \n \n \"RolesPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{manley_roles_2015,\n\ttitle = {Roles of dispersal and predation in determining seedling recruitment patterns in a foundational marine angiosperm},\n\tvolume = {533},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v533/p109-120/},\n\tdoi = {10.3354/meps11363},\n\tabstract = {Seed dispersal and seed predation are 2 important processes in the early life history of plants. These mechanisms have been described extensively in terrestrial plants and have resulted in the creation of various models to describe seedling recruitment with increasing distance from the parent plant. However, it is unclear whether theoretical models derived from terrestrial studies apply to marine angiosperms. We performed observational and experimental tests of seed dispersal mechanisms in a marine environment to elucidate patterns of seed dispersal and predation in a foundational marine angiosperm, eelgrass Zostera marina. We also modeled seed dispersal and predation to explore how recruitment varies under different scenarios of predator activity and abundance. We found that seed densities were highest within and adjacent to vegetated areas. Predation pressure was low overall, and there was no significant difference in predation pressure between vegetated and unvegetated areas. Seedling densities were highly correlated with seed densities from the previous year, suggesting that seed predation had a limited impact on population recruitment. These results are consistent with the invariant survival model, which states that seed survivorship has no spatial trend. The theoretical scenarios we generated suggest that a low abundance of highly mobile, generalist predators may explain the patterns observed in our system. Therefore, seedling establishment rates are almost solely attributable and inversely proportional to distance from the parent plant. The results from this study have important implications for the recovery and restoration of these highly threatened coastal ecosystems.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Manley, Stephen R. and Orth, Robert J. and Ruiz-Montoya, Leonardo},\n\tmonth = aug,\n\tyear = {2015},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {109--120},\n}\n\n
\n
\n\n\n
\n Seed dispersal and seed predation are 2 important processes in the early life history of plants. These mechanisms have been described extensively in terrestrial plants and have resulted in the creation of various models to describe seedling recruitment with increasing distance from the parent plant. However, it is unclear whether theoretical models derived from terrestrial studies apply to marine angiosperms. We performed observational and experimental tests of seed dispersal mechanisms in a marine environment to elucidate patterns of seed dispersal and predation in a foundational marine angiosperm, eelgrass Zostera marina. We also modeled seed dispersal and predation to explore how recruitment varies under different scenarios of predator activity and abundance. We found that seed densities were highest within and adjacent to vegetated areas. Predation pressure was low overall, and there was no significant difference in predation pressure between vegetated and unvegetated areas. Seedling densities were highly correlated with seed densities from the previous year, suggesting that seed predation had a limited impact on population recruitment. These results are consistent with the invariant survival model, which states that seed survivorship has no spatial trend. The theoretical scenarios we generated suggest that a low abundance of highly mobile, generalist predators may explain the patterns observed in our system. Therefore, seedling establishment rates are almost solely attributable and inversely proportional to distance from the parent plant. The results from this study have important implications for the recovery and restoration of these highly threatened coastal ecosystems.\n
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\n \n\n \n \n \n \n \n \n Restoration recovers population structure and landscape genetic connectivity in a dispersal-limited ecosystem.\n \n \n \n \n\n\n \n Reynolds, L. K.; Waycott, M.; and McGlathery, K. J.\n\n\n \n\n\n\n Journal of Ecology,1288–1297. October 2015.\n Publisher: John Wiley & Sons, Ltd\n\n\n\n
\n\n\n\n \n \n \"RestorationPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{reynolds_restoration_2015,\n\ttitle = {Restoration recovers population structure and landscape genetic connectivity in a dispersal-limited ecosystem},\n\tissn = {0022-0477},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.12116@10.1111/(ISSN)1365-2745.marinevirtualissue},\n\tdoi = {10.1111/1365-2745.12116@10.1111/(ISSN)1365-2745.marinevirtualissue},\n\tabstract = {Summary Ecological restoration assists the recovery of degraded ecosystems; however, restoration can have deleterious effects such as outbreeding depression when source material is not chosen carefully and has non-local adaptations. We surveyed 23 eelgrass (Zostera marina L.) populations along the North American Atlantic coast to evaluate genetic structure and connectivity among restored and naturally recruited populations. While populations along the North America Atlantic coast were genetically distinctive, significant migration was detected among populations. All estimates of connectivity (FST, migration rate base on rare alleles, and Bayesian modelling) showed a general north to south pattern of migration, corresponding to the typical long-shore currents in this region. Individual naturally recruited meadows in the Virginia coastal bays appear to be the result of dispersal from different meadows north of the region. This supports the hypothesis that recruitment into this region is typically a slow, episodic process rather than a permanent, continuous connection between the populations. While natural recovery of populations that were catastrophically lost in the 1930s has been slow, large-scale seed-based restoration has been very successful at quickly restoring landscape-scale areal coverage (over 1600 ha in just 10 years). Our results show that restoration was also successful at restoring meadows with high genetic diversity. Naturally recruited meadows were less diverse and exhibited signs of genetic drift. Synthesis. Our analyses demonstrate that metapopulation dynamics are important to the natural recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales; however, natural recovery processes are slow and inefficient at recovering genetic diversity and population structure when recruitment barriers exist, such as a limited seed source. Seed-based restoration provides a greater abundance of propagules, rapidly facilitates the recovery of populations with higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. First-order estimates indicated that the genetic diversity achieved by active restoration in 10 years would have otherwise taken between 125 and 185 years to achieve through natural recruitment events.},\n\turldate = {2020-05-15},\n\tjournal = {Journal of Ecology},\n\tauthor = {Reynolds, Laura K. and Waycott, Michelle and McGlathery, Karen J.},\n\tmonth = oct,\n\tyear = {2015},\n\tnote = {Publisher: John Wiley \\& Sons, Ltd},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {1288--1297},\n}\n\n
\n
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\n Summary Ecological restoration assists the recovery of degraded ecosystems; however, restoration can have deleterious effects such as outbreeding depression when source material is not chosen carefully and has non-local adaptations. We surveyed 23 eelgrass (Zostera marina L.) populations along the North American Atlantic coast to evaluate genetic structure and connectivity among restored and naturally recruited populations. While populations along the North America Atlantic coast were genetically distinctive, significant migration was detected among populations. All estimates of connectivity (FST, migration rate base on rare alleles, and Bayesian modelling) showed a general north to south pattern of migration, corresponding to the typical long-shore currents in this region. Individual naturally recruited meadows in the Virginia coastal bays appear to be the result of dispersal from different meadows north of the region. This supports the hypothesis that recruitment into this region is typically a slow, episodic process rather than a permanent, continuous connection between the populations. While natural recovery of populations that were catastrophically lost in the 1930s has been slow, large-scale seed-based restoration has been very successful at quickly restoring landscape-scale areal coverage (over 1600 ha in just 10 years). Our results show that restoration was also successful at restoring meadows with high genetic diversity. Naturally recruited meadows were less diverse and exhibited signs of genetic drift. Synthesis. Our analyses demonstrate that metapopulation dynamics are important to the natural recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales; however, natural recovery processes are slow and inefficient at recovering genetic diversity and population structure when recruitment barriers exist, such as a limited seed source. Seed-based restoration provides a greater abundance of propagules, rapidly facilitates the recovery of populations with higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. First-order estimates indicated that the genetic diversity achieved by active restoration in 10 years would have otherwise taken between 125 and 185 years to achieve through natural recruitment events.\n
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\n \n\n \n \n \n \n \n \n Epifaunal invertebrates as predators of juvenile bay scallops (Argopecten irradians).\n \n \n \n \n\n\n \n Lefcheck, J. S.; van Montfrans, J.; Orth, R. J.; Schmitt, E. L.; Duffy, J. E.; and Luckenbach, M. W.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology, 454: 18–25. May 2014.\n \n\n\n\n
\n\n\n\n \n \n \"EpifaunalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{lefcheck_epifaunal_2014,\n\ttitle = {Epifaunal invertebrates as predators of juvenile bay scallops ({Argopecten} irradians)},\n\tvolume = {454},\n\tissn = {0022-0981},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0022098114000252},\n\tdoi = {10.1016/j.jembe.2014.01.014},\n\tabstract = {Predation strongly influences populations of numerous benthic invertebrates, although many predation studies to date have focused on macroscopic individuals, ignoring critical early life stages. Juveniles of the bay scallop, Argopecten irradians, settle and grow on the blades of eelgrass, Zostera marina, then migrate to the sediment surface when their mobility and size provide a refuge from benthic predators. During their time in the eelgrass canopy, scallops co-occur with a diverse array of small invertebrates, including peracarid and small decapod crustaceans, whose role as predators is largely unexplored. We measured consumption by amphipods, isopods, and a shrimp on recently settled bay scallops ranging in size from 0.5 to {\\textgreater}1.5mm in a series of 24-hour experimental laboratory assays. These invertebrate predators, which were common concurrent epifaunal surveys of restored eelgrass beds in the mid-Atlantic, consumed up to 63\\% day−1 of juvenile scallops when the scallops were {\\textless}1mm, but predation impacts decreased as scallops exceeded this size. Our data have implications for current restoration of both bay scallops and their eelgrass habitat, suggesting that previously unrecognized consumers may significantly affect scallop population dynamics at early life stages.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Lefcheck, Jonathan S. and van Montfrans, Jacques and Orth, Robert J. and Schmitt, Erika L. and Duffy, J. Emmett and Luckenbach, Mark W.},\n\tmonth = may,\n\tyear = {2014},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {18--25},\n}\n\n
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\n Predation strongly influences populations of numerous benthic invertebrates, although many predation studies to date have focused on macroscopic individuals, ignoring critical early life stages. Juveniles of the bay scallop, Argopecten irradians, settle and grow on the blades of eelgrass, Zostera marina, then migrate to the sediment surface when their mobility and size provide a refuge from benthic predators. During their time in the eelgrass canopy, scallops co-occur with a diverse array of small invertebrates, including peracarid and small decapod crustaceans, whose role as predators is largely unexplored. We measured consumption by amphipods, isopods, and a shrimp on recently settled bay scallops ranging in size from 0.5 to \\textgreater1.5mm in a series of 24-hour experimental laboratory assays. These invertebrate predators, which were common concurrent epifaunal surveys of restored eelgrass beds in the mid-Atlantic, consumed up to 63% day−1 of juvenile scallops when the scallops were \\textless1mm, but predation impacts decreased as scallops exceeded this size. Our data have implications for current restoration of both bay scallops and their eelgrass habitat, suggesting that previously unrecognized consumers may significantly affect scallop population dynamics at early life stages.\n
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\n \n\n \n \n \n \n \n \n Trends in Abundance Indices of Fishes in Maryland’s Coastal Bays During 1972–2009.\n \n \n \n \n\n\n \n Pincin, J.; Wilberg, M. J.; Harris, L.; and Willey, A.\n\n\n \n\n\n\n Estuaries and Coasts, 37(4): 791–800. July 2014.\n \n\n\n\n
\n\n\n\n \n \n \"TrendsPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{pincin_trends_2014,\n\ttitle = {Trends in {Abundance} {Indices} of {Fishes} in {Maryland}’s {Coastal} {Bays} {During} 1972–2009},\n\tvolume = {37},\n\tissn = {1559-2731},\n\turl = {https://doi.org/10.1007/s12237-013-9735-8},\n\tdoi = {10.1007/s12237-013-9735-8},\n\tabstract = {Maryland’s coastal bays provide habitat for juveniles of many commercially and recreationally important species of shellfish and finfish. Since 1972, the Maryland Department of Natural Resources has conducted the Maryland Coastal Bays Trawl and Seine Survey to monitor the populations of key species. The survey has undergone substantial spatial and methodological changes affecting the interpretation of simple indices of abundance. We developed generalized linear models to standardize the indices of abundance of five commonly caught fish species: Atlantic menhaden Brevoortia tyrannus, weakfish Cynoscion regalis, spot Leiostomus xanthurus, bay anchovy Anchoa mitchilli, and summer flounder Paralichthys dentatus. Density declined significantly since 1972 for menhaden, bay anchovy, and spot in at least one region within the coastal bays. The northern bays had significantly higher densities than the southern bays for all species. Changes in abundance indices of the five species examined were not related to sea grass coverage, temperature, salinity, nitrogen-to-phosphorus ratios, and other habitat variables but were likely a result of stock-wide recruitment processes.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-15},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Pincin, Jennifer and Wilberg, Michael J. and Harris, Lora and Willey, Angel},\n\tmonth = jul,\n\tyear = {2014},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {791--800},\n}\n\n
\n
\n\n\n
\n Maryland’s coastal bays provide habitat for juveniles of many commercially and recreationally important species of shellfish and finfish. Since 1972, the Maryland Department of Natural Resources has conducted the Maryland Coastal Bays Trawl and Seine Survey to monitor the populations of key species. The survey has undergone substantial spatial and methodological changes affecting the interpretation of simple indices of abundance. We developed generalized linear models to standardize the indices of abundance of five commonly caught fish species: Atlantic menhaden Brevoortia tyrannus, weakfish Cynoscion regalis, spot Leiostomus xanthurus, bay anchovy Anchoa mitchilli, and summer flounder Paralichthys dentatus. Density declined significantly since 1972 for menhaden, bay anchovy, and spot in at least one region within the coastal bays. The northern bays had significantly higher densities than the southern bays for all species. Changes in abundance indices of the five species examined were not related to sea grass coverage, temperature, salinity, nitrogen-to-phosphorus ratios, and other habitat variables but were likely a result of stock-wide recruitment processes.\n
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\n \n\n \n \n \n \n \n \n Multiple timescale processes drive ecosystem metabolism in eelgrass (Zostera marina) meadows.\n \n \n \n \n\n\n \n Rheuban, J. E.; Berg, P.; and McGlathery, K. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 507: 1–13. July 2014.\n \n\n\n\n
\n\n\n\n \n \n \"MultiplePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{rheuban_multiple_2014,\n\ttitle = {Multiple timescale processes drive ecosystem metabolism in eelgrass ({Zostera} marina) meadows},\n\tvolume = {507},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v507/p1-13/},\n\tdoi = {10.3354/meps10843},\n\tabstract = {The oxygen flux between benthic ecosystems and the overlying water column is a measure of metabolic status and a commonly used proxy for carbon cycling. In this study, oxygen flux was measured seasonally using the eddy correlation technique in a restored eelgrass (Zostera marina L.) meadow in the Virginia coastal bays (USA). In 5 intensive field campaigns, we covered seasonal variation in oxygen metabolism and biomass with overlap in late summer to observe interannual variability. The high-resolution measurements allowed identification of the drivers of metabolism at multiple timescales: minute to hourly, daily, and monthly to seasonally. There was a strong correlation between nighttime hourly fluxes and current velocity that varied seasonally with seagrass shoot density and temperature. No similar relationship was observed during the day. A hysteresis effect in oxygen flux throughout the day was observed during October and August that was most likely due to increased respiration (R) in the afternoon. In October, net community production was 90\\% lower in the afternoon than in the morning at the same irradiance. From this hysteresis, we calculated that daytime R may be up to 2.5-fold larger than nighttime R. The magnitudes of daily gross primary production (GPP) and R were well correlated throughout the year with close to a 1:1 ratio that reflected a tight coupling between GPP and R on daily to seasonal timescales. Our results document the dynamic nature of oxygen fluxes that, when integrated over time, translate into highly variable rates of ecosystem metabolism over daily to seasonal timescales. This variation must be incorporated to accurately determine trophic status.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Rheuban, Jennie E. and Berg, Peter and McGlathery, Karen J.},\n\tmonth = jul,\n\tyear = {2014},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {1--13},\n}\n\n
\n
\n\n\n
\n The oxygen flux between benthic ecosystems and the overlying water column is a measure of metabolic status and a commonly used proxy for carbon cycling. In this study, oxygen flux was measured seasonally using the eddy correlation technique in a restored eelgrass (Zostera marina L.) meadow in the Virginia coastal bays (USA). In 5 intensive field campaigns, we covered seasonal variation in oxygen metabolism and biomass with overlap in late summer to observe interannual variability. The high-resolution measurements allowed identification of the drivers of metabolism at multiple timescales: minute to hourly, daily, and monthly to seasonally. There was a strong correlation between nighttime hourly fluxes and current velocity that varied seasonally with seagrass shoot density and temperature. No similar relationship was observed during the day. A hysteresis effect in oxygen flux throughout the day was observed during October and August that was most likely due to increased respiration (R) in the afternoon. In October, net community production was 90% lower in the afternoon than in the morning at the same irradiance. From this hysteresis, we calculated that daytime R may be up to 2.5-fold larger than nighttime R. The magnitudes of daily gross primary production (GPP) and R were well correlated throughout the year with close to a 1:1 ratio that reflected a tight coupling between GPP and R on daily to seasonal timescales. Our results document the dynamic nature of oxygen fluxes that, when integrated over time, translate into highly variable rates of ecosystem metabolism over daily to seasonal timescales. This variation must be incorporated to accurately determine trophic status.\n
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\n \n\n \n \n \n \n \n \n Eutrophication of a Maryland/Virginia Coastal Lagoon: a Tipping Point, Ecosystem Changes, and Potential Causes.\n \n \n \n \n\n\n \n Glibert, P. M.; Hinkle, D. C.; Sturgis, B.; and Jesien, R. V.\n\n\n \n\n\n\n Estuaries and Coasts, 37(1): 128–146. March 2014.\n \n\n\n\n
\n\n\n\n \n \n \"EutrophicationPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{glibert_eutrophication_2014,\n\ttitle = {Eutrophication of a {Maryland}/{Virginia} {Coastal} {Lagoon}: a {Tipping} {Point}, {Ecosystem} {Changes}, and {Potential} {Causes}},\n\tvolume = {37},\n\tissn = {1559-2731},\n\tshorttitle = {Eutrophication of a {Maryland}/{Virginia} {Coastal} {Lagoon}},\n\turl = {https://doi.org/10.1007/s12237-013-9630-3},\n\tdoi = {10.1007/s12237-013-9630-3},\n\tabstract = {Water quality in the Maryland/Virginia Coastal Bays has been declining for many years from anthropogenic inputs, but conditions appear to have worsened abruptly following a shift from long-term dry to long-term wet conditions in the early 2000s. Annually and regionally averaged total nitrogen concentrations are approximately twofold higher, but ammonium (NH4+) concentrations are up to an order of magnitude higher than in the early 1990s. Averaged nitrate concentrations, however, changed to a lesser degree throughout the time course; water column concentrations remain very low. Total phosphorus has only increased in some bay segments, but increases in phosphate (PO43−) have been more pervasive. There were differences in the year in which large increases in each nutrient were first noted: PO43− in {\\textasciitilde}2001–2002, followed by NH4+ {\\textasciitilde}a year later. The effects of a combination of steadily increasing anthropogenic nutrient increases from development, superimposed on nutrient loads from farming and animal operations, and groundwater inputs were accelerated by changes in freshwater flow and associated, negatively reinforcing, biogeochemical responses. Regionally, chlorophyll a concentrations have increased, and submersed aquatic vegetation has decreased. The system is now characterized by sustained summer picoplanktonic algal blooms, both brown tide and cyanobacteria. The retentive nature of this coastal lagoon combined with the reducing nature of the system will make these changes difficult to reverse if the current dual nutrient management practices are not accelerated.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-15},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Glibert, Patricia M. and Hinkle, Deborah C. and Sturgis, Brian and Jesien, Roman V.},\n\tmonth = mar,\n\tyear = {2014},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {128--146},\n}\n\n
\n
\n\n\n
\n Water quality in the Maryland/Virginia Coastal Bays has been declining for many years from anthropogenic inputs, but conditions appear to have worsened abruptly following a shift from long-term dry to long-term wet conditions in the early 2000s. Annually and regionally averaged total nitrogen concentrations are approximately twofold higher, but ammonium (NH4+) concentrations are up to an order of magnitude higher than in the early 1990s. Averaged nitrate concentrations, however, changed to a lesser degree throughout the time course; water column concentrations remain very low. Total phosphorus has only increased in some bay segments, but increases in phosphate (PO43−) have been more pervasive. There were differences in the year in which large increases in each nutrient were first noted: PO43− in ~2001–2002, followed by NH4+ ~a year later. The effects of a combination of steadily increasing anthropogenic nutrient increases from development, superimposed on nutrient loads from farming and animal operations, and groundwater inputs were accelerated by changes in freshwater flow and associated, negatively reinforcing, biogeochemical responses. Regionally, chlorophyll a concentrations have increased, and submersed aquatic vegetation has decreased. The system is now characterized by sustained summer picoplanktonic algal blooms, both brown tide and cyanobacteria. The retentive nature of this coastal lagoon combined with the reducing nature of the system will make these changes difficult to reverse if the current dual nutrient management practices are not accelerated.\n
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\n \n\n \n \n \n \n \n \n Seasonal Growth and Senescence of a Zostera marina Seagrass Meadow Alters Wave-Dominated Flow and Sediment Suspension Within a Coastal Bay.\n \n \n \n \n\n\n \n Hansen, J. C. R.; and Reidenbach, M. A.\n\n\n \n\n\n\n Estuaries and Coasts, 36(6): 1099–1114. November 2013.\n \n\n\n\n
\n\n\n\n \n \n \"SeasonalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{hansen_seasonal_2013,\n\ttitle = {Seasonal {Growth} and {Senescence} of a {Zostera} marina {Seagrass} {Meadow} {Alters} {Wave}-{Dominated} {Flow} and {Sediment} {Suspension} {Within} a {Coastal} {Bay}},\n\tvolume = {36},\n\tissn = {1559-2731},\n\turl = {https://doi.org/10.1007/s12237-013-9620-5},\n\tdoi = {10.1007/s12237-013-9620-5},\n\tabstract = {Tidally driven flows, waves, and suspended sediment concentrations were monitored seasonally within a Zostera marina seagrass (eelgrass) meadow located in a shallow (1–2 m depth) coastal bay. Eelgrass meadows were found to reduce velocities approximately 60 \\% in the summer and 40 \\% in the winter compared to an adjacent unvegetated site. Additionally, the seagrass meadow served to dampen wave heights for all seasons except during winter when seagrass meadow development was at a minimum. Although wave heights were attenuated across the meadow, orbital motions caused by waves were able to effectively penetrate through the canopy, inducing wave-enhanced bottom shear stress (τb). Within the seagrass meadow, τbwas greater than the critical stress threshold (=0.04 Pa) necessary to induce sediment suspension 80–85 \\% of the sampling period in the winter and spring, but only 55 \\% of the time in the summer. At the unvegetated site, τbwas above the critical threshold greater than 90 \\% of the time across all seasons. During low seagrass coverage in the winter, near-bed turbulence levels were enhanced, likely caused by stem–wake interaction with the sparse canopy. Reduction in τbwithin the seagrass meadow during the summer correlated to a 60 \\% reduction in suspended sediment concentrations but in winter, suspended sediment was enhanced compared to the unvegetated site. With minimal seagrass coverage, τband wave statistics were similar to unvegetated regions; however, during high seagrass coverage, sediment stabilization increased light availability for photosynthesis and created a positive feedback for seagrass growth.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-05-15},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Hansen, Jennifer C. R. and Reidenbach, Matthew A.},\n\tmonth = nov,\n\tyear = {2013},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {1099--1114},\n}\n\n
\n
\n\n\n
\n Tidally driven flows, waves, and suspended sediment concentrations were monitored seasonally within a Zostera marina seagrass (eelgrass) meadow located in a shallow (1–2 m depth) coastal bay. Eelgrass meadows were found to reduce velocities approximately 60 % in the summer and 40 % in the winter compared to an adjacent unvegetated site. Additionally, the seagrass meadow served to dampen wave heights for all seasons except during winter when seagrass meadow development was at a minimum. Although wave heights were attenuated across the meadow, orbital motions caused by waves were able to effectively penetrate through the canopy, inducing wave-enhanced bottom shear stress (τb). Within the seagrass meadow, τbwas greater than the critical stress threshold (=0.04 Pa) necessary to induce sediment suspension 80–85 % of the sampling period in the winter and spring, but only 55 % of the time in the summer. At the unvegetated site, τbwas above the critical threshold greater than 90 % of the time across all seasons. During low seagrass coverage in the winter, near-bed turbulence levels were enhanced, likely caused by stem–wake interaction with the sparse canopy. Reduction in τbwithin the seagrass meadow during the summer correlated to a 60 % reduction in suspended sediment concentrations but in winter, suspended sediment was enhanced compared to the unvegetated site. With minimal seagrass coverage, τband wave statistics were similar to unvegetated regions; however, during high seagrass coverage, sediment stabilization increased light availability for photosynthesis and created a positive feedback for seagrass growth.\n
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\n \n\n \n \n \n \n \n \n Eelgrass recovery in the coastal bays of the Virginia Coast Reserve, USA.\n \n \n \n \n\n\n \n Orth, R. J.; and McGlathery, K. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 173–176. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"EelgrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_eelgrass_2012,\n\ttitle = {Eelgrass recovery in the coastal bays of the {Virginia} {Coast} {Reserve}, {USA}},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p173-176/},\n\tdoi = {10.3354/meps09596},\n\tabstract = {Coastal bay systems are prominent features of coastlines on nearly all continents and are vulnerable to long-term environmental changes related to climate and nutrient over-enrichment. Eelgrass Zostera marina disappeared in the 1930s from the coastal bays of the Virginia Coast Reserve, USA, primarily due to a wasting disease and the effects of a hurricane. It has been re-established recently as a result of a large-scale seeding and restoration effort. The contributions to this Theme Section provide the most comprehensive account available of large-scale recovery of an eelgrass ecosystem, the consequences of the state change from a bare-sediment system to eelgrass dominance, and projections of meadow resilience to future climate change scenarios.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and McGlathery, Karen J.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {173--176},\n}\n\n
\n
\n\n\n
\n Coastal bay systems are prominent features of coastlines on nearly all continents and are vulnerable to long-term environmental changes related to climate and nutrient over-enrichment. Eelgrass Zostera marina disappeared in the 1930s from the coastal bays of the Virginia Coast Reserve, USA, primarily due to a wasting disease and the effects of a hurricane. It has been re-established recently as a result of a large-scale seeding and restoration effort. The contributions to this Theme Section provide the most comprehensive account available of large-scale recovery of an eelgrass ecosystem, the consequences of the state change from a bare-sediment system to eelgrass dominance, and projections of meadow resilience to future climate change scenarios.\n
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\n \n\n \n \n \n \n \n \n Eelgrass survival in two contrasting systems: role of turbidity and summer water temperatures.\n \n \n \n \n\n\n \n Moore, K. A.; Shields, E. C.; Parrish, D. B.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 247–258. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"EelgrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{moore_eelgrass_2012,\n\ttitle = {Eelgrass survival in two contrasting systems: role of turbidity and summer water temperatures},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Eelgrass survival in two contrasting systems},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p247-258/},\n\tdoi = {10.3354/meps09578},\n\tabstract = {Eelgrass Zostera marina L. distribution patterns in the mid-Atlantic region of the USA have shown complex changes, with recovery from losses in the 1930s varying between the coastal lagoons and Chesapeake Bay. Restoration efforts in the coastal bays of Virginia introduced Z. marina back to this system, and expansion since 2005 has averaged 66\\% yr−1. In contrast, Chesapeake Bay has experienced 2\\% expansion and has undergone 2 significant die-off events, in 2005 and 2010. We used a temperature-dependent light model to show that from 2005 to 2010 during daylight periods in the summer, coastal bay beds received at least 100\\% of their light requirements 24\\% of the time, while beds in the lower Chesapeake Bay only met this 6\\% of the time. Summer light attenuation (Kd) and temperatures from continuous monitoring at 2 additional Chesapeake Bay sites in 2010 suggest that the greater tidal range and proximity of the coastal bays to cooler ocean waters may ameliorate influences of exposure to stressful high water temperature conditions compared to Chesapeake Bay. A temperature difference of 1°C combined with a Kd difference of 0.5 m−1 at 1 m depth results in a 30\\% difference in available light as a proportion of community light requirements. These differences are critical between survival and decline in these perennial populations growing near the southern limits of their range. Without an increase in available light, Chesapeake Bay populations may be severely reduced or eliminated, while coastal bay populations, because of their proximity to cooler Atlantic waters, may become the refuge populations for this region.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Moore, Kenneth A. and Shields, Erin C. and Parrish, David B. and Orth, Robert J.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {247--258},\n}\n\n
\n
\n\n\n
\n Eelgrass Zostera marina L. distribution patterns in the mid-Atlantic region of the USA have shown complex changes, with recovery from losses in the 1930s varying between the coastal lagoons and Chesapeake Bay. Restoration efforts in the coastal bays of Virginia introduced Z. marina back to this system, and expansion since 2005 has averaged 66% yr−1. In contrast, Chesapeake Bay has experienced 2% expansion and has undergone 2 significant die-off events, in 2005 and 2010. We used a temperature-dependent light model to show that from 2005 to 2010 during daylight periods in the summer, coastal bay beds received at least 100% of their light requirements 24% of the time, while beds in the lower Chesapeake Bay only met this 6% of the time. Summer light attenuation (Kd) and temperatures from continuous monitoring at 2 additional Chesapeake Bay sites in 2010 suggest that the greater tidal range and proximity of the coastal bays to cooler ocean waters may ameliorate influences of exposure to stressful high water temperature conditions compared to Chesapeake Bay. A temperature difference of 1°C combined with a Kd difference of 0.5 m−1 at 1 m depth results in a 30% difference in available light as a proportion of community light requirements. These differences are critical between survival and decline in these perennial populations growing near the southern limits of their range. Without an increase in available light, Chesapeake Bay populations may be severely reduced or eliminated, while coastal bay populations, because of their proximity to cooler Atlantic waters, may become the refuge populations for this region.\n
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\n\n\n
\n \n\n \n \n \n \n \n \n Eelgrass restoration by seed maintains genetic diversity: case study from a coastal bay system.\n \n \n \n \n\n\n \n Reynolds, L. K.; Waycott, M.; McGlathery, K. J.; Orth, R. J.; and Zieman, J. C.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 223–233. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"EelgrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{reynolds_eelgrass_2012,\n\ttitle = {Eelgrass restoration by seed maintains genetic diversity: case study from a coastal bay system},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Eelgrass restoration by seed maintains genetic diversity},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p223-233/},\n\tdoi = {10.3354/meps09386},\n\tabstract = {Genetic diversity is positively associated with plant fitness, stability, and the provision of ecosystem services. Preserving genetic diversity is therefore considered an important component of ecosystem restoration as well as a measure of its success. We examined the genetic diversity of restored Zostera marina meadows in a coastal bay system along the USA mid-Atlantic coast using microsatellite markers to compare donor and recipient meadows. We show that donor meadows in Chesapeake Bay have high genetic diversity and that this diversity is maintained in meadows restored with seeds in the Virginia coastal bays. No evidence of inbreeding depression was detected (FIS −0.2 to 0) in either donor or recipient meadows, which is surprising because high levels of inbreeding were expected following the population contractions that occurred in Chesapeake Bay populations due to disease and heat stress. Additionally, there was no evidence for selection of genotypes at the restoration sites, suggesting that as long as donor sites are chosen carefully, issues that diminish fitness and survival such as heterosis or out-breeding depression can be avoided. A cluster analysis showed that, in addition to the Chesapeake Bay populations that acted as donors, the Virginia coastal bay populations shared a genetic signal with Chincoteague Bay populations, their closest neighbor to the north, suggesting that natural recruitment into the area may be occurring and augmenting restored populations. We hypothesize that the high genetic diversity in seagrasses restored using seeds rather than adult plants confers a greater level of ecosystem resilience to the restored meadows.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Reynolds, Laura K. and Waycott, Michelle and McGlathery, Karen J. and Orth, Robert J. and Zieman, Joseph C.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {223--233},\n}\n\n
\n
\n\n\n
\n Genetic diversity is positively associated with plant fitness, stability, and the provision of ecosystem services. Preserving genetic diversity is therefore considered an important component of ecosystem restoration as well as a measure of its success. We examined the genetic diversity of restored Zostera marina meadows in a coastal bay system along the USA mid-Atlantic coast using microsatellite markers to compare donor and recipient meadows. We show that donor meadows in Chesapeake Bay have high genetic diversity and that this diversity is maintained in meadows restored with seeds in the Virginia coastal bays. No evidence of inbreeding depression was detected (FIS −0.2 to 0) in either donor or recipient meadows, which is surprising because high levels of inbreeding were expected following the population contractions that occurred in Chesapeake Bay populations due to disease and heat stress. Additionally, there was no evidence for selection of genotypes at the restoration sites, suggesting that as long as donor sites are chosen carefully, issues that diminish fitness and survival such as heterosis or out-breeding depression can be avoided. A cluster analysis showed that, in addition to the Chesapeake Bay populations that acted as donors, the Virginia coastal bay populations shared a genetic signal with Chincoteague Bay populations, their closest neighbor to the north, suggesting that natural recruitment into the area may be occurring and augmenting restored populations. We hypothesize that the high genetic diversity in seagrasses restored using seeds rather than adult plants confers a greater level of ecosystem resilience to the restored meadows.\n
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\n \n\n \n \n \n \n \n \n Seed addition facilitates eelgrass recovery in a coastal bay system.\n \n \n \n \n\n\n \n Orth, R. J.; Moore, K. A.; Marion, S. R.; Wilcox, D. J.; and Parrish, D. B.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 177–195. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"SeedPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_seed_2012,\n\ttitle = {Seed addition facilitates eelgrass recovery in a coastal bay system},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p177-195/},\n\tdoi = {10.3354/meps09522},\n\tabstract = {Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those exports. Estimates of annual patch vegetative expansion showed mean estimated diameter increasing at varying rates from 10 to 36 cm yr−1, consistent with rhizome elongation rates reported for Z. marina. Water quality data collected over 7 yr by spatially intensive sampling, as well as fixed-location continuous monitoring, document conditions in all 4 bays that are adequate to support Z. marina growth. In particular, median chlorophyll levels for the entire sampling period were between 5 and 6 µg l−1 for each of the bays, and median turbidity levels, while exhibiting seasonal differences, were between 8 and 9 NTU. The recovery of Z. marina initiated in this coastal bay system may be unique in seagrass recovery studies because of how the recovery was initiated (seeds rather than adult plants), how rapidly it occurred (years rather than decades), and the explicit demonstration of how one meadow modulated water clarity and altered sediments as it developed and expanded. Our results offer a new perspective on the role seeds can play in recovery dynamics at large spatial scales.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A. and Marion, Scott R. and Wilcox, David J. and Parrish, David B.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {177--195},\n}\n\n
\n
\n\n\n
\n Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those exports. Estimates of annual patch vegetative expansion showed mean estimated diameter increasing at varying rates from 10 to 36 cm yr−1, consistent with rhizome elongation rates reported for Z. marina. Water quality data collected over 7 yr by spatially intensive sampling, as well as fixed-location continuous monitoring, document conditions in all 4 bays that are adequate to support Z. marina growth. In particular, median chlorophyll levels for the entire sampling period were between 5 and 6 µg l−1 for each of the bays, and median turbidity levels, while exhibiting seasonal differences, were between 8 and 9 NTU. The recovery of Z. marina initiated in this coastal bay system may be unique in seagrass recovery studies because of how the recovery was initiated (seeds rather than adult plants), how rapidly it occurred (years rather than decades), and the explicit demonstration of how one meadow modulated water clarity and altered sediments as it developed and expanded. Our results offer a new perspective on the role seeds can play in recovery dynamics at large spatial scales.\n
\n\n\n
\n\n\n
\n \n\n \n \n \n \n \n \n Seedling establishment in eelgrass: seed burial effects on winter losses of developing seedlings.\n \n \n \n \n\n\n \n Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 197–207. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"SeedlingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{marion_seedling_2012,\n\ttitle = {Seedling establishment in eelgrass: seed burial effects on winter losses of developing seedlings},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Seedling establishment in eelgrass},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p197-207/},\n\tdoi = {10.3354/meps09612},\n\tabstract = {Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked in separate destructively-sampled plots. Sediment height change was measured, and sediment disturbance depth was estimated by deploying cores layered with tracer particles and examining tracer loss upon core retrieval. We found a low rate of seedling establishment 6 mo after seeding (1.2, 3.8, and 2.8\\% for surface seeds at the 3 sites) that was largely due to seed and seedling loss rather than to germination failure, with 90\\% of seeds retrieved after December having germinated. Seed burial significantly enhanced seedling establishment at 2 of 3 sites (40.4, 16.8, and 10.3\\% establishment for buried seeds). Seed loss occurred mostly within the first month of the experiment, and was most severe for seeds at the sediment surface. Indicator core results showed widespread disturbance of sediments to depths that could have dislodged early seedlings developing from surface seeds, and to a lesser degree seedlings from buried seeds. Our findings help identify the nature and timing of a substantial Z. marina seedling establishment bottleneck in our region, and show that some of the key processes pivotal to Z. marina recruitment dynamics and optimal restoration strategies involve physical sediment−seedling interactions rather than seed germination.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Marion, Scott R. and Orth, Robert J.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {197--207},\n}\n\n
\n
\n\n\n
\n Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked in separate destructively-sampled plots. Sediment height change was measured, and sediment disturbance depth was estimated by deploying cores layered with tracer particles and examining tracer loss upon core retrieval. We found a low rate of seedling establishment 6 mo after seeding (1.2, 3.8, and 2.8% for surface seeds at the 3 sites) that was largely due to seed and seedling loss rather than to germination failure, with 90% of seeds retrieved after December having germinated. Seed burial significantly enhanced seedling establishment at 2 of 3 sites (40.4, 16.8, and 10.3% establishment for buried seeds). Seed loss occurred mostly within the first month of the experiment, and was most severe for seeds at the sediment surface. Indicator core results showed widespread disturbance of sediments to depths that could have dislodged early seedlings developing from surface seeds, and to a lesser degree seedlings from buried seeds. Our findings help identify the nature and timing of a substantial Z. marina seedling establishment bottleneck in our region, and show that some of the key processes pivotal to Z. marina recruitment dynamics and optimal restoration strategies involve physical sediment−seedling interactions rather than seed germination.\n
\n\n\n
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\n \n\n \n \n \n \n \n \n Recovery trajectories during state change from bare sediment to eelgrass dominance.\n \n \n \n \n\n\n \n McGlathery, K. J.; Reynolds, L. K.; Cole, L. W.; Orth, R. J.; Marion, S. R.; and Schwarzschild, A.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 209–221. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"RecoveryPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{mcglathery_recovery_2012,\n\ttitle = {Recovery trajectories during state change from bare sediment to eelgrass dominance},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p209-221/},\n\tdoi = {10.3354/meps09574},\n\tabstract = {Seagrasses are important foundation species in shallow coastal ecosystems that provide critical ecosystem services including stabilizing sediment, sequestering carbon and nutrients, and providing habitat and an energy source for a diverse fauna. We followed the recovery of functional (primary productivity, carbon and nitrogen sequestration, sediment deposition) and structural (shoot density, biomass, plant morphometrics) attributes of Zostera marina (eelgrass) meadows in replicate large plots (0.2 to 0.4 ha) restored by seeding in successive years, resulting in a chronosequence of sites from 0 (unvegetated) to 9 yr since seeding. Shoot density was the structural metric that changed most significantly, with an initial 4 yr lag, and a rapid, linear increase in plots 6 to 9 yr after seeding. Changes in Z. marina aerial productivity, sediment organic content, and exchangeable ammonium showed a similar trend with an initial 4 yr lag period before differences were observed from initial bare sediment conditions. After 9 yr, Z. marina meadows had 20× higher rates of areal productivity than 1 to 3 yr old meadows, double the organic matter and exchangeable ammonium concentrations, 3× more carbon and 4× more nitrogen, and had accumulated and retained finer particles than bare, unvegetated sediments. These results demonstrate the reinstatement of key ecosystem services with successful large-scale restoration, although none of the parameters reached an asymptote after 9 yr, indicating that at least a decade is required for these attributes to be fully restored, even in an area with high habitat suitability. Survivorship along a depth gradient showed that {\\textasciitilde}1.6 m (mean sea level) is the maximum depth limit for Z. marina, which matches the ‘tipping point’ for survival predicted for this system from a non-linear hydrodynamic/seagrass growth model.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {McGlathery, Karen J. and Reynolds, Laura K. and Cole, Luke W. and Orth, Robert J. and Marion, Scott R. and Schwarzschild, Arthur},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {209--221},\n}\n\n
\n
\n\n\n
\n Seagrasses are important foundation species in shallow coastal ecosystems that provide critical ecosystem services including stabilizing sediment, sequestering carbon and nutrients, and providing habitat and an energy source for a diverse fauna. We followed the recovery of functional (primary productivity, carbon and nitrogen sequestration, sediment deposition) and structural (shoot density, biomass, plant morphometrics) attributes of Zostera marina (eelgrass) meadows in replicate large plots (0.2 to 0.4 ha) restored by seeding in successive years, resulting in a chronosequence of sites from 0 (unvegetated) to 9 yr since seeding. Shoot density was the structural metric that changed most significantly, with an initial 4 yr lag, and a rapid, linear increase in plots 6 to 9 yr after seeding. Changes in Z. marina aerial productivity, sediment organic content, and exchangeable ammonium showed a similar trend with an initial 4 yr lag period before differences were observed from initial bare sediment conditions. After 9 yr, Z. marina meadows had 20× higher rates of areal productivity than 1 to 3 yr old meadows, double the organic matter and exchangeable ammonium concentrations, 3× more carbon and 4× more nitrogen, and had accumulated and retained finer particles than bare, unvegetated sediments. These results demonstrate the reinstatement of key ecosystem services with successful large-scale restoration, although none of the parameters reached an asymptote after 9 yr, indicating that at least a decade is required for these attributes to be fully restored, even in an area with high habitat suitability. Survivorship along a depth gradient showed that ~1.6 m (mean sea level) is the maximum depth limit for Z. marina, which matches the ‘tipping point’ for survival predicted for this system from a non-linear hydrodynamic/seagrass growth model.\n
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\n \n\n \n \n \n \n \n \n Nitrogen fixation in restored eelgrass meadows.\n \n \n \n \n\n\n \n Cole, L. W.; and McGlathery, K. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 235–246. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"NitrogenPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{cole_nitrogen_2012,\n\ttitle = {Nitrogen fixation in restored eelgrass meadows},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p235-246/},\n\tdoi = {10.3354/meps09512},\n\tabstract = {Biological nitrogen (N2) fixation is the primary input of new nitrogen (N) to marine systems, and is important in meeting the N demands of primary producers. In this study, we determined whether restoration of the eelgrass Zostera marina L. in a shallow coastal bay facilitated increasing rates of N2 fixation as the meadows aged. Rates of N2 fixation were measured in a system that had been devoid of eelgrass following local extinction in the 1930s until restoration by seeding began in 2001. Restored meadows of different ages were compared to nearby bare sediment sites during summer peak metabolism over 2 yr. Nutrient addition by N2 fixation was enhanced as the meadows aged. Rates of N2 fixation in the older (7 to 8 yr old) meadows were 2.7 times more than the younger (2 to 3 yr old) meadows (average 390 and 146 µmol N m−2 d−1, respectively), and 28 times more than bare sediments (average 14 µmol N m−2 d−1). Heterotrophic epiphyte bacteria fixed approximately 90\\% of the total N2 in Z. marina meadows of both age classes. Both sediment and epiphyte N2 fixation were strongly related to Z. marina density and sediment organic content, suggesting that shoot density increases the positive feedback of plant presence on N2 fixation through the release of organic carbon exudates into the rhizosphere and phyllosphere, and the build up of sediment organic matter also increases. The N provided through fixation represented a large fraction (20.5 to 30\\%) of the total N demand to support eelgrass aboveground growth during this period of peak summertime production.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Cole, Luke W. and McGlathery, Karen J.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {235--246},\n}\n\n
\n
\n\n\n
\n Biological nitrogen (N2) fixation is the primary input of new nitrogen (N) to marine systems, and is important in meeting the N demands of primary producers. In this study, we determined whether restoration of the eelgrass Zostera marina L. in a shallow coastal bay facilitated increasing rates of N2 fixation as the meadows aged. Rates of N2 fixation were measured in a system that had been devoid of eelgrass following local extinction in the 1930s until restoration by seeding began in 2001. Restored meadows of different ages were compared to nearby bare sediment sites during summer peak metabolism over 2 yr. Nutrient addition by N2 fixation was enhanced as the meadows aged. Rates of N2 fixation in the older (7 to 8 yr old) meadows were 2.7 times more than the younger (2 to 3 yr old) meadows (average 390 and 146 µmol N m−2 d−1, respectively), and 28 times more than bare sediments (average 14 µmol N m−2 d−1). Heterotrophic epiphyte bacteria fixed approximately 90% of the total N2 in Z. marina meadows of both age classes. Both sediment and epiphyte N2 fixation were strongly related to Z. marina density and sediment organic content, suggesting that shoot density increases the positive feedback of plant presence on N2 fixation through the release of organic carbon exudates into the rhizosphere and phyllosphere, and the build up of sediment organic matter also increases. The N provided through fixation represented a large fraction (20.5 to 30%) of the total N demand to support eelgrass aboveground growth during this period of peak summertime production.\n
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\n \n\n \n \n \n \n \n \n Enhancement of sediment suspension and nutrient flux by benthic macrophytes at low biomass.\n \n \n \n \n\n\n \n Lawson, S. E.; McGlathery, K. J.; and Wiberg, P. L.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 259–270. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"EnhancementPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{lawson_enhancement_2012,\n\ttitle = {Enhancement of sediment suspension and nutrient flux by benthic macrophytes at low biomass},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p259-270/},\n\tdoi = {10.3354/meps09579},\n\tabstract = {In shallow coastal ecosystems where most of the seafloor typically lies within the photic zone, benthic autotrophs dominate primary production and mediate nutrient cycling and sediment stability. Because of their different structure and metabolic rates, the 2 functional groups of benthic macrophytes (seagrasses, macroalgae) have distinct influences on benthic−pelagic coupling. Most research to date in these soft-bottomed systems has focused on mature seagrass meadows where shoot densities are high and on dense macroalgal mats that accumulate in response to eutrophication. Relatively little is known about the influence of low-biomass stands of seagrass and macroalgae on nutrient fluxes and sediment suspension. Using an erosion microcosm with controlled forcing conditions, we tested the effects of the eelgrass Zostera marina L. and the invasive macroalga Gracilaria vermiculophylla on sediment suspension and nutrient fluxes under high-flow conditions. At low densities, G. vermiculophylla increased sediment suspension and increased the nutrient flux from the sediment to the water column. For macroalgae, increased sediment suspension is likely due to dislodgement of sediment particles by bedload transport of the algae. In this case, the increase in sediment transport was reflected in an increase in nutrient flux from the sediment, showing that modification of physical forcing by benthic primary producers can also affect nutrient flux. The presence or absence of Z. marina did not have a significant effect on nutrient flux. However, the results suggest that there may be a range of low shoot densities for which storm-like flows increase sediment suspension to values higher than those expected for a bare sediment bed.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Lawson, S. E. and McGlathery, K. J. and Wiberg, P. L.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {259--270},\n}\n\n
\n
\n\n\n
\n In shallow coastal ecosystems where most of the seafloor typically lies within the photic zone, benthic autotrophs dominate primary production and mediate nutrient cycling and sediment stability. Because of their different structure and metabolic rates, the 2 functional groups of benthic macrophytes (seagrasses, macroalgae) have distinct influences on benthic−pelagic coupling. Most research to date in these soft-bottomed systems has focused on mature seagrass meadows where shoot densities are high and on dense macroalgal mats that accumulate in response to eutrophication. Relatively little is known about the influence of low-biomass stands of seagrass and macroalgae on nutrient fluxes and sediment suspension. Using an erosion microcosm with controlled forcing conditions, we tested the effects of the eelgrass Zostera marina L. and the invasive macroalga Gracilaria vermiculophylla on sediment suspension and nutrient fluxes under high-flow conditions. At low densities, G. vermiculophylla increased sediment suspension and increased the nutrient flux from the sediment to the water column. For macroalgae, increased sediment suspension is likely due to dislodgement of sediment particles by bedload transport of the algae. In this case, the increase in sediment transport was reflected in an increase in nutrient flux from the sediment, showing that modification of physical forcing by benthic primary producers can also affect nutrient flux. The presence or absence of Z. marina did not have a significant effect on nutrient flux. However, the results suggest that there may be a range of low shoot densities for which storm-like flows increase sediment suspension to values higher than those expected for a bare sediment bed.\n
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\n \n\n \n \n \n \n \n \n Wave and tidally driven flows in eelgrass beds and their effect on sediment suspension.\n \n \n \n \n\n\n \n Hansen, J. C. R.; and Reidenbach, M. A.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 271–287. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"WavePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{hansen_wave_2012,\n\ttitle = {Wave and tidally driven flows in eelgrass beds and their effect on sediment suspension},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p271-287/},\n\tdoi = {10.3354/meps09225},\n\tabstract = {Seagrass beds alter their hydrodynamic environment by inducing drag on the flow, thereby attenuating wave energy and near-bottom currents. This alters the turbulent structure and shear stresses within and around the seagrass bed that are responsible for the suspension and deposition of sediment. To quantify these interactions, velocity, pressure, and sediment measurements were obtained across a density gradient of an eelgrass Zostera marina bed within a shallow coastal bay (1 to 2 m depth). Eelgrass beds were found to reduce near-bottom mean velocities by 70 to 90\\%, while wave heights were reduced 45 to 70\\% compared to an adjacent unvegetated region. Wave orbital velocities within the eelgrass bed were reduced by 20\\% compared to flow above the bed, primarily acting as a low-pass filter by removing high-frequency wave motion. However, relatively little reduction in wave energy occurred at lower wave frequencies, suggesting that longer period waves were able to effectively penetrate the seagrass meadow. Average bottom shear stresses (τb) at the unvegetated region were τb = 0.17 ± 0.08 N m–2, significantly larger than the critical stress threshold necessary for sediment entrainment of 0.04 N m–2. Within the eelgrass bed, τb = 0.03 ± 0.02 N m–2 and stresses were below the critical stress threshold during 80\\% of the time period of measurement. Expansion of eelgrass within the coastal bay has thus altered the dynamics of the seafloor from an erosional environment to one that promotes deposition of suspended sediment, enhancing light penetration throughout the water column and creating a positive feedback for eelgrass growth.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Hansen, Jennifer C. R. and Reidenbach, Matthew A.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {271--287},\n}\n\n
\n
\n\n\n
\n Seagrass beds alter their hydrodynamic environment by inducing drag on the flow, thereby attenuating wave energy and near-bottom currents. This alters the turbulent structure and shear stresses within and around the seagrass bed that are responsible for the suspension and deposition of sediment. To quantify these interactions, velocity, pressure, and sediment measurements were obtained across a density gradient of an eelgrass Zostera marina bed within a shallow coastal bay (1 to 2 m depth). Eelgrass beds were found to reduce near-bottom mean velocities by 70 to 90%, while wave heights were reduced 45 to 70% compared to an adjacent unvegetated region. Wave orbital velocities within the eelgrass bed were reduced by 20% compared to flow above the bed, primarily acting as a low-pass filter by removing high-frequency wave motion. However, relatively little reduction in wave energy occurred at lower wave frequencies, suggesting that longer period waves were able to effectively penetrate the seagrass meadow. Average bottom shear stresses (τb) at the unvegetated region were τb = 0.17 ± 0.08 N m–2, significantly larger than the critical stress threshold necessary for sediment entrainment of 0.04 N m–2. Within the eelgrass bed, τb = 0.03 ± 0.02 N m–2 and stresses were below the critical stress threshold during 80% of the time period of measurement. Expansion of eelgrass within the coastal bay has thus altered the dynamics of the seafloor from an erosional environment to one that promotes deposition of suspended sediment, enhancing light penetration throughout the water column and creating a positive feedback for eelgrass growth.\n
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\n \n\n \n \n \n \n \n \n Modeling the effects of climate change on eelgrass stability and resilience: future scenarios and leading indicators of collapse.\n \n \n \n \n\n\n \n Carr, J. A.; D’Odorico, P.; McGlathery, K. J.; and Wiberg, P. L.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 289–301. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"ModelingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{carr_modeling_2012,\n\ttitle = {Modeling the effects of climate change on eelgrass stability and resilience: future scenarios and leading indicators of collapse},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Modeling the effects of climate change on eelgrass stability and resilience},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p289-301/},\n\tdoi = {10.3354/meps09556},\n\tabstract = {Seagrass meadows influence local hydrodynamics in coastal bays, resulting in a decrease in the shear stress acting on the underlying bed sediment. The reduced sediment suspension and water column turbidity creates a more favorable light environment for further seagrass growth. This positive feedback is strong enough to induce depth-dependent bistable dynamics with 2 possible stable states, an extant meadow and a bare sediment surface. A coupled vegetation-growth hydrodynamic model was used to investigate eelgrass stability and leading indicators of ecosystem shift under the effects of sea-level rise and increases in water temperature associated with climate change. The model was applied to Hog Island Bay, a shallow coastal bay within the Virginia Coast Reserve, USA, where eelgrass restoration efforts are ongoing. The results indicate that while extant eelgrass meadows are likely to tolerate sea-level rise, an increase in the frequency of days when summer water temperature exceeds 30°C will cause more frequent summer die-offs. This increase in the number of higher temperature disturbance events is likely to push a dense meadow initially located within the bistable depth range (1.6 to 1.8 m mean sea level) toward and eventually past a critical bifurcation point, from which recovery is not possible. We identified 2 leading indicators of a meadow nearing this bifurcation point, both associated with the number of leaves per shoot: ‘flickering,’ which reflects conspicuous fluctuations from one attractor to the other across the threshold, and ‘slowing down,’ which is the decreased recovery from perturbations as a system gets close to a threshold. Our model indicates that the eelgrass in these coastal bays has limited resilience to increases in water temperatures predicted from current climate change models.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Carr, Joel A. and D’Odorico, Paolo and McGlathery, Karen J. and Wiberg, Patricia L.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {289--301},\n}\n\n
\n
\n\n\n
\n Seagrass meadows influence local hydrodynamics in coastal bays, resulting in a decrease in the shear stress acting on the underlying bed sediment. The reduced sediment suspension and water column turbidity creates a more favorable light environment for further seagrass growth. This positive feedback is strong enough to induce depth-dependent bistable dynamics with 2 possible stable states, an extant meadow and a bare sediment surface. A coupled vegetation-growth hydrodynamic model was used to investigate eelgrass stability and leading indicators of ecosystem shift under the effects of sea-level rise and increases in water temperature associated with climate change. The model was applied to Hog Island Bay, a shallow coastal bay within the Virginia Coast Reserve, USA, where eelgrass restoration efforts are ongoing. The results indicate that while extant eelgrass meadows are likely to tolerate sea-level rise, an increase in the frequency of days when summer water temperature exceeds 30°C will cause more frequent summer die-offs. This increase in the number of higher temperature disturbance events is likely to push a dense meadow initially located within the bistable depth range (1.6 to 1.8 m mean sea level) toward and eventually past a critical bifurcation point, from which recovery is not possible. We identified 2 leading indicators of a meadow nearing this bifurcation point, both associated with the number of leaves per shoot: ‘flickering,’ which reflects conspicuous fluctuations from one attractor to the other across the threshold, and ‘slowing down,’ which is the decreased recovery from perturbations as a system gets close to a threshold. Our model indicates that the eelgrass in these coastal bays has limited resilience to increases in water temperatures predicted from current climate change models.\n
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\n\n\n
\n \n\n \n \n \n \n \n \n Dissolved oxygen fluxes and ecosystem metabolism in an eelgrass (Zostera marina) meadow measured with the eddy correlation technique.\n \n \n \n \n\n\n \n Hume, A. C.; Berg, P.; and McGlathery, K. J.\n\n\n \n\n\n\n Limnology and Oceanography, 56(1): 86–96. 2011.\n _eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2011.56.1.0086\n\n\n\n
\n\n\n\n \n \n \"DissolvedPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{hume_dissolved_2011,\n\ttitle = {Dissolved oxygen fluxes and ecosystem metabolism in an eelgrass ({Zostera} marina) meadow measured with the eddy correlation technique},\n\tvolume = {56},\n\tcopyright = {© 2011, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tissn = {1939-5590},\n\turl = {https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.2011.56.1.0086},\n\tdoi = {10.4319/lo.2011.56.1.0086},\n\tabstract = {Dissolved oxygen (DO) fluxes were measured by eddy correlation to estimate net ecosystem metabolism (NEM) during summer in a restored eelgrass (Zostera marina) meadow and a nearby, unvegetated sediment. This technique measures benthic fluxes under true in situ light and hydrodynamic conditions, integrates over a large area (typically {\\textgreater} 100 m2), and captures short-term variations. DO fluxes measured through eight 24-h periods showed pronounced temporal variation driven by light and local hydrodynamics on multiple scales: hour-to-hour, within each daily cycle, and between deployments. The magnitude of variation between hours during single deployments equaled that between deployments, indicating that short-term variation must be included for metabolism estimates to be accurate. DO flux variability was significantly correlated to mean current velocity for the seagrass site and to significant wave height for the unvegetated site. Fluxes measured in low-flow conditions analogous to many chamber and core incubations underestimated those measured in higher-flow conditions typical of in situ conditions by a factor of 2–6. Rates of gross primary production (GPP), respiration (R), and NEM varied substantially between individual deployments, reflecting variations in light and hydrodynamic conditions, and daily values of GPP and R for individual deployments were tightly linked. Average daily NEM of the seagrass site was higher than that of the unvegetated site; the seagrass site was in metabolic balance, and the unvegetated site showed a tendency toward net heterotrophy during this midsummer period.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-15},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Hume, Andrew C. and Berg, Peter and McGlathery, Karen J.},\n\tyear = {2011},\n\tnote = {\\_eprint: https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2011.56.1.0086},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {86--96},\n}\n\n
\n
\n\n\n
\n Dissolved oxygen (DO) fluxes were measured by eddy correlation to estimate net ecosystem metabolism (NEM) during summer in a restored eelgrass (Zostera marina) meadow and a nearby, unvegetated sediment. This technique measures benthic fluxes under true in situ light and hydrodynamic conditions, integrates over a large area (typically \\textgreater 100 m2), and captures short-term variations. DO fluxes measured through eight 24-h periods showed pronounced temporal variation driven by light and local hydrodynamics on multiple scales: hour-to-hour, within each daily cycle, and between deployments. The magnitude of variation between hours during single deployments equaled that between deployments, indicating that short-term variation must be included for metabolism estimates to be accurate. DO flux variability was significantly correlated to mean current velocity for the seagrass site and to significant wave height for the unvegetated site. Fluxes measured in low-flow conditions analogous to many chamber and core incubations underestimated those measured in higher-flow conditions typical of in situ conditions by a factor of 2–6. Rates of gross primary production (GPP), respiration (R), and NEM varied substantially between individual deployments, reflecting variations in light and hydrodynamic conditions, and daily values of GPP and R for individual deployments were tightly linked. Average daily NEM of the seagrass site was higher than that of the unvegetated site; the seagrass site was in metabolic balance, and the unvegetated site showed a tendency toward net heterotrophy during this midsummer period.\n
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\n \n\n \n \n \n \n \n \n Eelgrass (Zostera marina L.) in the Chesapeake Bay Region of Mid-Atlantic Coast of the USA: Challenges in Conservation and Restoration.\n \n \n \n \n\n\n \n Orth, R. J.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Estuaries and Coasts, 33(1): 139–150. January 2010.\n \n\n\n\n
\n\n\n\n \n \n \"EelgrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_eelgrass_2010,\n\ttitle = {Eelgrass ({Zostera} marina {L}.) in the {Chesapeake} {Bay} {Region} of {Mid}-{Atlantic} {Coast} of the {USA}: {Challenges} in {Conservation} and {Restoration}},\n\tvolume = {33},\n\tissn = {1559-2731},\n\tshorttitle = {Eelgrass ({Zostera} marina {L}.) in the {Chesapeake} {Bay} {Region} of {Mid}-{Atlantic} {Coast} of the {USA}},\n\turl = {https://doi.org/10.1007/s12237-009-9234-0},\n\tdoi = {10.1007/s12237-009-9234-0},\n\tabstract = {Decreases in seagrass abundance reported from numerous locations around the world suggest that seagrass are facing a global crisis. Declining water quality has been identified as the leading cause for most losses. Increased public awareness is leading to expanded efforts for conservation and restoration. Here, we report on abundance patterns and environmental issues facing eelgrass (Zostera marina), the dominant seagrass species in the Chesapeake Bay region in the mid-Atlantic coast of the USA, and describe efforts to promote its protection and restoration. Eelgrass beds in Chesapeake Bay and Chincoteague Bay, which had started to recover from earlier diebacks, have shown a downward trend in the last 5–10 years, while eelgrass beds in the Virginia coastal bays have substantially increased in abundance during this same time period. Declining water quality appears to be the primary reason for the decreased abundance, but a recent baywide dieback in 2005 was associated with higher than usual summer water temperatures along with poor water clarity. The success of eelgrass in the Virginia coastal bays has been attributed, in part, to slightly cooler water due to their proximity to the Atlantic Ocean. A number of policies and regulations have been adopted in this region since 1983 aimed at protecting and restoring both habitat and water quality. Eelgrass abundance is now one of the criteria for assessing attainment of water clarity goals in this region. Numerous transplant projects have been aimed at restoring eelgrass but most have not succeeded beyond 1 to 2 years. A notable exception is the large-scale restoration effort in the Virginia coastal bays, where seeds distributed beginning in 2001 has initiated an expanding recovery process. Our research on eelgrass abundance patterns in the Chesapeake Bay region and the processes contributing to these patterns have provided a scientific background for management strategies for the protection and restoration of eelgrass and insights into the causes of success and failure of restoration efforts that may have applications to other seagrass systems.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-15},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Orth, Robert J. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tmonth = jan,\n\tyear = {2010},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {139--150},\n}\n\n
\n
\n\n\n
\n Decreases in seagrass abundance reported from numerous locations around the world suggest that seagrass are facing a global crisis. Declining water quality has been identified as the leading cause for most losses. Increased public awareness is leading to expanded efforts for conservation and restoration. Here, we report on abundance patterns and environmental issues facing eelgrass (Zostera marina), the dominant seagrass species in the Chesapeake Bay region in the mid-Atlantic coast of the USA, and describe efforts to promote its protection and restoration. Eelgrass beds in Chesapeake Bay and Chincoteague Bay, which had started to recover from earlier diebacks, have shown a downward trend in the last 5–10 years, while eelgrass beds in the Virginia coastal bays have substantially increased in abundance during this same time period. Declining water quality appears to be the primary reason for the decreased abundance, but a recent baywide dieback in 2005 was associated with higher than usual summer water temperatures along with poor water clarity. The success of eelgrass in the Virginia coastal bays has been attributed, in part, to slightly cooler water due to their proximity to the Atlantic Ocean. A number of policies and regulations have been adopted in this region since 1983 aimed at protecting and restoring both habitat and water quality. Eelgrass abundance is now one of the criteria for assessing attainment of water clarity goals in this region. Numerous transplant projects have been aimed at restoring eelgrass but most have not succeeded beyond 1 to 2 years. A notable exception is the large-scale restoration effort in the Virginia coastal bays, where seeds distributed beginning in 2001 has initiated an expanding recovery process. Our research on eelgrass abundance patterns in the Chesapeake Bay region and the processes contributing to these patterns have provided a scientific background for management strategies for the protection and restoration of eelgrass and insights into the causes of success and failure of restoration efforts that may have applications to other seagrass systems.\n
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\n \n\n \n \n \n \n \n \n Effects of sediment organic content and hydrodynamic conditions on the growth and distribution of Zostera marina.\n \n \n \n \n\n\n \n Wicks, E. C.; Koch, E. W.; O’Neil, J. M.; and Elliston, K.\n\n\n \n\n\n\n Marine Ecology Progress Series, 378: 71–80. March 2009.\n \n\n\n\n
\n\n\n\n \n \n \"EffectsPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{wicks_effects_2009,\n\ttitle = {Effects of sediment organic content and hydrodynamic conditions on the growth and distribution of {Zostera} marina},\n\tvolume = {378},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v378/p71-80/},\n\tdoi = {10.3354/meps07885},\n\tabstract = {The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content {\\textgreater} 4\\%, especially compared with areas with sediment organic content {\\textless} 4\\%. In contrast, in a mesocosm experiment, Z. marina thrived in organic rich (4 to 6\\%) sediment, developing long leaves and disproportionately short roots. Such plants have high drag and low anchoring capacity. As a result, Z. marina plants grown in organic rich sediment are more likely to be dislodged than are plants grown in organic poor sand. We hypothesize that when organic rich sediments are found in hydrodynamically active areas, a mismatch occurs between plant morphology and the physical environment, leading to the loss of seagrasses due to uprooting. Therefore, sediment organic content limitations in seagrass habitats need to be evaluated within the local hydrodynamic settings. Fine organic sediment may be less limiting to seagrasses in quiescent waters while sand with low organic content may be required for seagrass survival in hydrodynamically active areas.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Wicks, E. Caroline and Koch, Evamaria W. and O’Neil, Judy M. and Elliston, Kahla},\n\tmonth = mar,\n\tyear = {2009},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {71--80},\n}\n\n
\n
\n\n\n
\n The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content \\textgreater 4%, especially compared with areas with sediment organic content \\textless 4%. In contrast, in a mesocosm experiment, Z. marina thrived in organic rich (4 to 6%) sediment, developing long leaves and disproportionately short roots. Such plants have high drag and low anchoring capacity. As a result, Z. marina plants grown in organic rich sediment are more likely to be dislodged than are plants grown in organic poor sand. We hypothesize that when organic rich sediments are found in hydrodynamically active areas, a mismatch occurs between plant morphology and the physical environment, leading to the loss of seagrasses due to uprooting. Therefore, sediment organic content limitations in seagrass habitats need to be evaluated within the local hydrodynamic settings. Fine organic sediment may be less limiting to seagrasses in quiescent waters while sand with low organic content may be required for seagrass survival in hydrodynamically active areas.\n
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\n \n\n \n \n \n \n \n \n Spatial characterization of environmental gradients in a coastal lagoon, Chincoteague Bay.\n \n \n \n \n\n\n \n Allen, T. R.; Tolvanen, H. T.; Oertel, G. F.; and McLeod, G. M.\n\n\n \n\n\n\n Estuaries and Coasts, 30(6): 959–977. December 2007.\n \n\n\n\n
\n\n\n\n \n \n \"SpatialPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{allen_spatial_2007,\n\ttitle = {Spatial characterization of environmental gradients in a coastal lagoon, {Chincoteague} {Bay}},\n\tvolume = {30},\n\tissn = {1559-2731},\n\turl = {https://doi.org/10.1007/BF02841388},\n\tdoi = {10.1007/BF02841388},\n\tabstract = {Spatial patterns of environmental processes are intrinsic yet complex components of estuaries. Spatial characterization of environmental gradients is a necessary step to better understand and classify estuarine environments. A geographic information system is developed to analyze the major abiotic environmental processes, to evaluate accuracy and spatial uncertainty, and to analyze potential zonation within the choked coastal lagoon of Chincoteague Bay in Maryland and Virginia, USA. Spatially extensive grid-based models of environmental gradients are constructed from existing geospatial and environmental databases, including tidal prism, bathymetry, salinity, wave exposure, and Secchi disk depth. Integration of wetland boundaries and bathymetric data provide for full basin analysis of flushing and tidal prism. Multivariate Principal Components Analysis demonstrates the covariation among gradients and provides an empirical approach to mapping multidimensional zones within the lagoon. The project documents the development of an estuarine geographic information system that can be used to analyze and compare estuarine environments and provide data for environmental decision making.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-05-15},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Allen, Thomas R. and Tolvanen, Harri T. and Oertel, George F. and McLeod, George M.},\n\tmonth = dec,\n\tyear = {2007},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {959--977},\n}\n\n
\n
\n\n\n
\n Spatial patterns of environmental processes are intrinsic yet complex components of estuaries. Spatial characterization of environmental gradients is a necessary step to better understand and classify estuarine environments. A geographic information system is developed to analyze the major abiotic environmental processes, to evaluate accuracy and spatial uncertainty, and to analyze potential zonation within the choked coastal lagoon of Chincoteague Bay in Maryland and Virginia, USA. Spatially extensive grid-based models of environmental gradients are constructed from existing geospatial and environmental databases, including tidal prism, bathymetry, salinity, wave exposure, and Secchi disk depth. Integration of wetland boundaries and bathymetric data provide for full basin analysis of flushing and tidal prism. Multivariate Principal Components Analysis demonstrates the covariation among gradients and provides an empirical approach to mapping multidimensional zones within the lagoon. The project documents the development of an estuarine geographic information system that can be used to analyze and compare estuarine environments and provide data for environmental decision making.\n
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\n\n\n
\n \n\n \n \n \n \n \n \n Eutrophication in shallow coastal bays and lagoons: the role of plants in the coastal filter.\n \n \n \n \n\n\n \n McGlathery, K. J.; Sundbäck, K.; and Anderson, I. C.\n\n\n \n\n\n\n Marine Ecology Progress Series, 348: 1–18. October 2007.\n \n\n\n\n
\n\n\n\n \n \n \"EutrophicationPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{mcglathery_eutrophication_2007,\n\ttitle = {Eutrophication in shallow coastal bays and lagoons: the role of plants in the coastal filter},\n\tvolume = {348},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Eutrophication in shallow coastal bays and lagoons},\n\turl = {https://www.int-res.com/abstracts/meps/v348/p1-18/},\n\tdoi = {10.3354/meps07132},\n\tabstract = {Nutrient loading to coastal bay ecosystems is of a similar magnitude as that to deeper, river-fed estuaries, yet our understanding of the eutrophication process in these shallow systems lags far behind. In this synthesis, we focus on one type of biotic feedback that influences eutrophication patterns in coastal bays—the important role of primary producers in the ‘coastal filter’. We discuss the 2 aspects of plant-mediated nutrient cycling as eutrophication induces a shift in primary producer dominance: (1) the fate of nutrients bound in plant biomass, and (2) the effects of primary producers on biogeochemical processes that influence nutrient retention. We suggest the following generalizations as eutrophication proceeds in coastal bays: (1)  Long-term retention of recalcitrant dissolved and particulate organic matter will decline as seagrasses are replaced by algae with less refractory material. (2) Benthic grazers buffer the early effects of nutrient enrichment, but consumption rates will decline as physico-chemical conditions stress consumer populations. (3) Mass transport of plant-bound nutrients will increase because attached perennial macrophytes will be replaced by unattached ephemeral algae that move with the water. (4) Denitrification will be an unimportant sink for N because primary producers typically outcompete bacteria for available N, and partitioning of nitrate reduction will shift to dissimilatory nitrate reduction to ammonium in later stages of eutrophication. In tropical/subtropical systems dominated by carbonate sediments, eutrophication will likely result in a positive feedback where increased sulfate reduction and sulfide accumulation in sediments will decrease P adsorption to Fe and enhance the release of P to the overlying water.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {McGlathery, Karen J. and Sundbäck, Kristina and Anderson, Iris C.},\n\tmonth = oct,\n\tyear = {2007},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {1--18},\n}\n\n
\n
\n\n\n
\n Nutrient loading to coastal bay ecosystems is of a similar magnitude as that to deeper, river-fed estuaries, yet our understanding of the eutrophication process in these shallow systems lags far behind. In this synthesis, we focus on one type of biotic feedback that influences eutrophication patterns in coastal bays—the important role of primary producers in the ‘coastal filter’. We discuss the 2 aspects of plant-mediated nutrient cycling as eutrophication induces a shift in primary producer dominance: (1) the fate of nutrients bound in plant biomass, and (2) the effects of primary producers on biogeochemical processes that influence nutrient retention. We suggest the following generalizations as eutrophication proceeds in coastal bays: (1) Long-term retention of recalcitrant dissolved and particulate organic matter will decline as seagrasses are replaced by algae with less refractory material. (2) Benthic grazers buffer the early effects of nutrient enrichment, but consumption rates will decline as physico-chemical conditions stress consumer populations. (3) Mass transport of plant-bound nutrients will increase because attached perennial macrophytes will be replaced by unattached ephemeral algae that move with the water. (4) Denitrification will be an unimportant sink for N because primary producers typically outcompete bacteria for available N, and partitioning of nitrate reduction will shift to dissimilatory nitrate reduction to ammonium in later stages of eutrophication. In tropical/subtropical systems dominated by carbonate sediments, eutrophication will likely result in a positive feedback where increased sulfate reduction and sulfide accumulation in sediments will decrease P adsorption to Fe and enhance the release of P to the overlying water.\n
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\n \n\n \n \n \n \n \n \n Linking Water Quality to Living Resources in a Mid-Atlantic Lagoon System, Usa.\n \n \n \n \n\n\n \n Wazniak, C. E.; Hall, M. R.; Carruthers, T. J. B.; Sturgis, B.; Dennison, W. C.; and Orth, R. J.\n\n\n \n\n\n\n Ecological Applications, 17(sp5): S64–S78. 2007.\n _eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/05-1554.1\n\n\n\n
\n\n\n\n \n \n \"LinkingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{wazniak_linking_2007,\n\ttitle = {Linking {Water} {Quality} to {Living} {Resources} in a {Mid}-{Atlantic} {Lagoon} {System}, {Usa}},\n\tvolume = {17},\n\tcopyright = {© 2007 by the Ecological Society of America},\n\tissn = {1939-5582},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/05-1554.1},\n\tdoi = {10.1890/05-1554.1},\n\tabstract = {The mid-Atlantic coastal bays are shallow coastal lagoons, separated from the Atlantic Ocean by barrier sand islands with oceanic exchanges restricted to narrow inlets. The relatively poor flushing of these lagoon systems makes them susceptible to eutrophication resulting from anthropogenic nutrient loadings. An intensive water quality and seagrass monitoring program was initiated to track ecological changes in the Maryland and Virginia coastal bays. The purpose of this study was to analyze existing monitoring data to determine status and trends in eutrophication and to determine any associations between water quality and living resources. Analysis of monitoring program data revealed several trends: (1) decadal decreases in nutrient and chlorophyll concentrations, followed by recently increasing trends; (2) decadal increases in seagrass coverage, followed by a recent period of no change; (3) blooms of macroalgae and brown tide microalgae; and (4) exceedance of water quality thresholds: chlorophyll a (15 μg/L), total nitrogen (0.65 mg/L or 46 μmol/L), total phosphorus (0.037 mg/L or 1.2 μmol/L), and dissolved oxygen (5 mg/L) in many areas within the Maryland coastal bays. The water quality thresholds were based on habitat requirements for living resources (seagrass and fish) and used to calculate a water quality index, which was used to compare the bay segments. Strong gradients in water quality were correlated to changes in seagrass coverage between segments. These factors indicate that these coastal bays are in a state of transition, with a suite of metrics indicating degrading conditions. Continued monitoring and intensified management will be required to avert exacerbation of the observed eutrophication trends. Coastal lagoons worldwide are experiencing similar degrading trends due to increasing human pressures, and assessing status and trends relative to biologically relevant thresholds can assist in determining monitoring and management priorities and goals.},\n\tlanguage = {en},\n\tnumber = {sp5},\n\turldate = {2020-05-15},\n\tjournal = {Ecological Applications},\n\tauthor = {Wazniak, Catherine E. and Hall, Matthew R. and Carruthers, Tim J. B. and Sturgis, Brian and Dennison, William C. and Orth, Robert J.},\n\tyear = {2007},\n\tnote = {\\_eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/05-1554.1},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {S64--S78},\n}\n\n
\n
\n\n\n
\n The mid-Atlantic coastal bays are shallow coastal lagoons, separated from the Atlantic Ocean by barrier sand islands with oceanic exchanges restricted to narrow inlets. The relatively poor flushing of these lagoon systems makes them susceptible to eutrophication resulting from anthropogenic nutrient loadings. An intensive water quality and seagrass monitoring program was initiated to track ecological changes in the Maryland and Virginia coastal bays. The purpose of this study was to analyze existing monitoring data to determine status and trends in eutrophication and to determine any associations between water quality and living resources. Analysis of monitoring program data revealed several trends: (1) decadal decreases in nutrient and chlorophyll concentrations, followed by recently increasing trends; (2) decadal increases in seagrass coverage, followed by a recent period of no change; (3) blooms of macroalgae and brown tide microalgae; and (4) exceedance of water quality thresholds: chlorophyll a (15 μg/L), total nitrogen (0.65 mg/L or 46 μmol/L), total phosphorus (0.037 mg/L or 1.2 μmol/L), and dissolved oxygen (5 mg/L) in many areas within the Maryland coastal bays. The water quality thresholds were based on habitat requirements for living resources (seagrass and fish) and used to calculate a water quality index, which was used to compare the bay segments. Strong gradients in water quality were correlated to changes in seagrass coverage between segments. These factors indicate that these coastal bays are in a state of transition, with a suite of metrics indicating degrading conditions. Continued monitoring and intensified management will be required to avert exacerbation of the observed eutrophication trends. Coastal lagoons worldwide are experiencing similar degrading trends due to increasing human pressures, and assessing status and trends relative to biologically relevant thresholds can assist in determining monitoring and management priorities and goals.\n
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\n \n\n \n \n \n \n \n \n SeagrassNet monitoring across the Americas: case studies of seagrass decline.\n \n \n \n \n\n\n \n Short, F. T.; Koch, E. W.; Creed, J. C.; Magalhães, K. M.; Fernandez, E.; and Gaeckle, J. L.\n\n\n \n\n\n\n Marine Ecology, 27(4): 277–289. 2006.\n _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1439-0485.2006.00095.x\n\n\n\n
\n\n\n\n \n \n \"SeagrassNetPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{short_seagrassnet_2006,\n\ttitle = {{SeagrassNet} monitoring across the {Americas}: case studies of seagrass decline},\n\tvolume = {27},\n\tissn = {1439-0485},\n\tshorttitle = {{SeagrassNet} monitoring across the {Americas}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1439-0485.2006.00095.x},\n\tdoi = {10.1111/j.1439-0485.2006.00095.x},\n\tabstract = {Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology},\n\tauthor = {Short, Frederick T. and Koch, Evamaria W. and Creed, Joel C. and Magalhães, Karine M. and Fernandez, Eric and Gaeckle, Jeffrey L.},\n\tyear = {2006},\n\tnote = {\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1439-0485.2006.00095.x},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {277--289},\n}\n\n
\n
\n\n\n
\n Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action.\n
\n\n\n
\n\n\n
\n \n\n \n \n \n \n \n \n Seagrass recovery in the Delmarva Coastal Bays, USA.\n \n \n \n \n\n\n \n Orth, R. J.; Luckenbach, M. L.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Aquatic Botany, 84(1): 26–36. January 2006.\n \n\n\n\n
\n\n\n\n \n \n \"SeagrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_seagrass_2006,\n\ttitle = {Seagrass recovery in the {Delmarva} {Coastal} {Bays}, {USA}},\n\tvolume = {84},\n\tissn = {0304-3770},\n\turl = {http://www.sciencedirect.com/science/article/pii/S030437700500149X},\n\tdoi = {10.1016/j.aquabot.2005.07.007},\n\tabstract = {Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319ha reported through 2003 compared to 2129ha in 1986, an average expansion rate of 305hayear−1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4m2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2ha in four coastal bays having no seagrass, totaling approximately 46ha through 2004. Successful germination (estimated at 5–10\\% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38\\% of the bottom in 52–0.4ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-15},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Luckenbach, Mark L. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tmonth = jan,\n\tyear = {2006},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {26--36},\n}\n\n
\n
\n\n\n
\n Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319ha reported through 2003 compared to 2129ha in 1986, an average expansion rate of 305hayear−1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4m2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2ha in four coastal bays having no seagrass, totaling approximately 46ha through 2004. Successful germination (estimated at 5–10% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38% of the bottom in 52–0.4ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds.\n
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\n \n\n \n \n \n \n \n \n The effect of sea level rise on seagrasses: Is sediment adjacent to retreating marshes suitable for seagrass growth?.\n \n \n \n \n\n\n \n Wicks, E. C.\n\n\n \n\n\n\n Ph.D. Thesis, December 2005.\n Accepted: 2006-02-04T08:06:20Z\n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@phdthesis{wicks_effect_2005,\n\ttype = {Thesis},\n\ttitle = {The effect of sea level rise on seagrasses: {Is} sediment adjacent to retreating marshes suitable for seagrass growth?},\n\tshorttitle = {The effect of sea level rise on seagrasses},\n\turl = {http://drum.lib.umd.edu/handle/1903/3277},\n\tabstract = {Salt marsh retreat resulting from sea level rise creates new subtidal substrate (old marsh peat) for seagrasses, which is usually unvegetated.  The hypothesis that sediment characteristics of old marsh peat are limiting to \\&lt;em\\&gt;Zostera marina\\&lt;/em\\&gt; was tested in Chincoteague Bay, Maryland and in controlled experiments.  A unique aspect of the study site is an eroding dune within the marsh that supplies sand to the subtidal.  The organic content and sulfide concentrations of old marsh peat were not limiting \\&lt;em\\&gt;Z. marina\\&lt;/em\\&gt; growth and seagrasses were able to colonize the old marsh peat if a layer of sand covered it.  The lack of \\&lt;em\\&gt;Z. marina\\&lt;em/\\&gt; in old marsh peat may be due to a plant morphology that is highly susceptible to dislodgement.  These findings suggest that seagrass distribution may be negatively affected by sea level rise as seagrasses may be unable to migrate shoreward due to unsuitable sediments adjacent to retreating marshes.},\n\tlanguage = {en\\_US},\n\turldate = {2020-05-15},\n\tauthor = {Wicks, Elinor Caroline},\n\tmonth = dec,\n\tyear = {2005},\n\tnote = {Accepted: 2006-02-04T08:06:20Z},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n}\n\n
\n
\n\n\n
\n Salt marsh retreat resulting from sea level rise creates new subtidal substrate (old marsh peat) for seagrasses, which is usually unvegetated. The hypothesis that sediment characteristics of old marsh peat are limiting to <em>Zostera marina</em> was tested in Chincoteague Bay, Maryland and in controlled experiments. A unique aspect of the study site is an eroding dune within the marsh that supplies sand to the subtidal. The organic content and sulfide concentrations of old marsh peat were not limiting <em>Z. marina</em> growth and seagrasses were able to colonize the old marsh peat if a layer of sand covered it. The lack of <em>Z. marina<em/> in old marsh peat may be due to a plant morphology that is highly susceptible to dislodgement. These findings suggest that seagrass distribution may be negatively affected by sea level rise as seagrasses may be unable to migrate shoreward due to unsuitable sediments adjacent to retreating marshes.\n
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\n \n\n \n \n \n \n \n \n Seed-density effects on germination and initial seedling establishment in eelgrass Zostera marina in the Chesapeake Bay region.\n \n \n \n \n\n\n \n Orth, R. J.; Fishman, J. R.; Harwell, M. C.; and Marion, S. R.\n\n\n \n\n\n\n Marine Ecology Progress Series, 250: 71–79. March 2003.\n \n\n\n\n
\n\n\n\n \n \n \"Seed-densityPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_seed-density_2003,\n\ttitle = {Seed-density effects on germination and initial seedling establishment in eelgrass {Zostera} marina in the {Chesapeake} {Bay} region},\n\tvolume = {250},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v250/p71-79/},\n\tdoi = {10.3354/meps250071},\n\tabstract = {The influence of Zostera marina L. seed-density on germination and initial seedling success was investigated using seed-addition field experiments at 2 scales in the Chesapeake Bay region in 1999 and 2000. We first tested whether\ngermination rates and initial seedling establishment were affected by initial seed-densities of 2.5, 25, 250, and 1250 seeds m-2 within 4 m2 plots. We then tested whether plot size affects germination rates, following the hypothesis\nthat rates of seed predation might be different in large and small plots. We broadcast seeds at a single density (500 seeds m-2) but at a much larger plot size (100 m2, or 25 times the size of the small plots). In the spring\nfollowing seed broadcast, seedlings were present in most 4 m2 plots (seedling densities of 0.6 to 15.4\\% of the number of seeds released in 1999, and 3.3 to 23.3\\% of those released in 2000) and in all 100 m2 plots (4.3\\% to 13.9\\%).\nSeed-density effects were not significant in 1999 or 2000, while site effects were significant in both years. The percentages of seedlings in the larger plots were similar to those in the smaller plots. These results suggest that there were no\ndensity-dependent effects on germination and initial seedling establishment, and that within the size range of plots examined in this study, such processes are not likely to be scale-dependent. The significant differences among the sites may be related to\nmicro-topographic complexities of the bottom caused by both biotic and abiotic factors that allow seeds to be retained close to where they settle. Our data, combined with previously published data on seed dispersal and patch dynamics, stress the\nimportance of conserving existing beds, regardless of bed size and shoot density, since these are sources of seeds that may establish new patches. The data may also help in developing strategies for the restoration of denuded sites using seeds instead of\nadult plants.},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and Fishman, James R. and Harwell, Matthew C. and Marion, Scott R.},\n\tmonth = mar,\n\tyear = {2003},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {71--79},\n}\n\n
\n
\n\n\n
\n The influence of Zostera marina L. seed-density on germination and initial seedling success was investigated using seed-addition field experiments at 2 scales in the Chesapeake Bay region in 1999 and 2000. We first tested whether germination rates and initial seedling establishment were affected by initial seed-densities of 2.5, 25, 250, and 1250 seeds m-2 within 4 m2 plots. We then tested whether plot size affects germination rates, following the hypothesis that rates of seed predation might be different in large and small plots. We broadcast seeds at a single density (500 seeds m-2) but at a much larger plot size (100 m2, or 25 times the size of the small plots). In the spring following seed broadcast, seedlings were present in most 4 m2 plots (seedling densities of 0.6 to 15.4% of the number of seeds released in 1999, and 3.3 to 23.3% of those released in 2000) and in all 100 m2 plots (4.3% to 13.9%). Seed-density effects were not significant in 1999 or 2000, while site effects were significant in both years. The percentages of seedlings in the larger plots were similar to those in the smaller plots. These results suggest that there were no density-dependent effects on germination and initial seedling establishment, and that within the size range of plots examined in this study, such processes are not likely to be scale-dependent. The significant differences among the sites may be related to micro-topographic complexities of the bottom caused by both biotic and abiotic factors that allow seeds to be retained close to where they settle. Our data, combined with previously published data on seed dispersal and patch dynamics, stress the importance of conserving existing beds, regardless of bed size and shoot density, since these are sources of seeds that may establish new patches. The data may also help in developing strategies for the restoration of denuded sites using seeds instead of adult plants.\n
\n\n\n
\n\n\n
\n \n\n \n \n \n \n \n \n Long-Distance Dispersal Potential in a Marine Macrophyte.\n \n \n \n \n\n\n \n Harwell, M. C.; and Orth, R. J.\n\n\n \n\n\n\n Ecology, 83(12): 3319–3330. 2002.\n _eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/0012-9658%282002%29083%5B3319%3ALDDPIA%5D2.0.CO%3B2\n\n\n\n
\n\n\n\n \n \n \"Long-DistancePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{harwell_long-distance_2002,\n\ttitle = {Long-{Distance} {Dispersal} {Potential} in a {Marine} {Macrophyte}},\n\tvolume = {83},\n\tcopyright = {© 2002 by the Ecological Society of America},\n\tissn = {1939-9170},\n\turl = {https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/0012-9658%282002%29083%5B3319%3ALDDPIA%5D2.0.CO%3B2},\n\tdoi = {10.1890/0012-9658(2002)083[3319:LDDPIA]2.0.CO;2},\n\tabstract = {Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2020-05-15},\n\tjournal = {Ecology},\n\tauthor = {Harwell, Matthew C. and Orth, Robert J.},\n\tyear = {2002},\n\tnote = {\\_eprint: https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/0012-9658\\%282002\\%29083\\%5B3319\\%3ALDDPIA\\%5D2.0.CO\\%3B2},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {3319--3330},\n}\n\n
\n
\n\n\n
\n Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.\n
\n\n\n
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\n \n\n \n \n \n \n \n \n Benthic infauna of eelgrass,Zostera marina, beds.\n \n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Chesapeake Science, 14(4): 258–269. December 1973.\n \n\n\n\n
\n\n\n\n \n \n \"BenthicPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_benthic_1973,\n\ttitle = {Benthic infauna of eelgrass,{Zostera} marina, beds},\n\tvolume = {14},\n\tissn = {0009-3262},\n\turl = {https://doi.org/10.2307/1350754},\n\tdoi = {10.2307/1350754},\n\tabstract = {The infauna ofZostera beds in the Chesapeake Bay-York River estuary and Chincoteague Bay was sampled in March and July 1970 using a corer. Sediments were fine sand or very fine sand. Sorting of sediments varied from poorly sorted to moderately well-sorted and appeared to be positively correlated with the density ofZostera at the respective stations.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-15},\n\tjournal = {Chesapeake Science},\n\tauthor = {Orth, Robert J.},\n\tmonth = dec,\n\tyear = {1973},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {258--269},\n}\n\n
\n
\n\n\n
\n The infauna ofZostera beds in the Chesapeake Bay-York River estuary and Chincoteague Bay was sampled in March and July 1970 using a corer. Sediments were fine sand or very fine sand. Sorting of sediments varied from poorly sorted to moderately well-sorted and appeared to be positively correlated with the density ofZostera at the respective stations.\n
\n\n\n
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\n \n\n \n \n \n \n \n \n Fishes of isle of wight and Assawoman bays near Ocean City, Maryland.\n \n \n \n \n\n\n \n Schwartz, F. J.\n\n\n \n\n\n\n Chesapeake Science, 5(4): 172–193. December 1964.\n \n\n\n\n
\n\n\n\n \n \n \"FishesPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{schwartz_fishes_1964,\n\ttitle = {Fishes of isle of wight and {Assawoman} bays near {Ocean} {City}, {Maryland}},\n\tvolume = {5},\n\tissn = {0009-3262},\n\turl = {https://doi.org/10.2307/1350562},\n\tdoi = {10.2307/1350562},\n\tabstract = {The occurrence of 104 species of fish belonging to 54 families and 87 genera in the Isle of Wight and Assawoman Bays near Ocean City, Maryland, is reported. These fish were collected in 1959, 1961, 1962, and 1963 by various gear. Each species is accompanied by some ecological notes pertaining to seasonal oscillations of species and populations, patterns of distribution in the bays, etc.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-15},\n\tjournal = {Chesapeake Science},\n\tauthor = {Schwartz, Frank J.},\n\tmonth = dec,\n\tyear = {1964},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {172--193},\n}\n\n
\n
\n\n\n
\n The occurrence of 104 species of fish belonging to 54 families and 87 genera in the Isle of Wight and Assawoman Bays near Ocean City, Maryland, is reported. These fish were collected in 1959, 1961, 1962, and 1963 by various gear. Each species is accompanied by some ecological notes pertaining to seasonal oscillations of species and populations, patterns of distribution in the bays, etc.\n
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\n \n\n \n \n \n \n \n \n Abundance of the Hard Clam Mercenaria Mercenaria in Relation to Environmental Factors.\n \n \n \n \n\n\n \n Wells, H. W.\n\n\n \n\n\n\n Ecology, 38(1): 123–128. 1957.\n Publisher: Ecological Society of America\n\n\n\n
\n\n\n\n \n \n \"AbundancePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{wells_abundance_1957,\n\ttitle = {Abundance of the {Hard} {Clam} {Mercenaria} {Mercenaria} in {Relation} to {Environmental} {Factors}},\n\tvolume = {38},\n\tissn = {0012-9658},\n\turl = {https://www.jstor.org/stable/1932134},\n\tdoi = {10.2307/1932134},\n\tnumber = {1},\n\turldate = {2020-05-15},\n\tjournal = {Ecology},\n\tauthor = {Wells, Harry W.},\n\tyear = {1957},\n\tnote = {Publisher: Ecological Society of America},\n\tkeywords = {Coastal Bays (Maryland and Virginia)},\n\tpages = {123--128},\n}\n\n
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\n  \n Distribution, Abundance, and Production\n \n \n (75)\n \n \n
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\n \n\n \n \n \n \n \n Intensive Water Quality Mapping of Nearshore and Mid-Channel Regions of the James River Relative to SAV Growth and Survival Using the DATAFLOW Surface Water Quality Mapping System.\n \n \n \n\n\n \n Moore, K.; Anderson, B.; and Wilcox, D. J\n\n\n \n\n\n\n ,56. .\n \n\n\n\n
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@article{moore_intensive_nodate,\n\ttitle = {Intensive {Water} {Quality} {Mapping} of {Nearshore} and {Mid}-{Channel} {Regions} of the {James} {River} {Relative} to {SAV} {Growth} and {Survival} {Using} the {DATAFLOW} {Surface} {Water} {Quality} {Mapping} {System}},\n\tlanguage = {en},\n\tauthor = {Moore, Ken and Anderson, Britt and Wilcox, David J},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {56},\n}\n\n
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\n \n\n \n \n \n \n \n \n Revegetation and Propagule Transport in the Tidal Potomac River.\n \n \n \n \n\n\n \n Rybicki, N.; and Carter, V.\n\n\n \n\n\n\n . .\n \n\n\n\n
\n\n\n\n \n \n \"RevegetationPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{rybicki_revegetation_nodate,\n\ttitle = {Revegetation and {Propagule} {Transport} in the {Tidal} {Potomac} {River}},\n\turl = {https://apps.dtic.mil/dtic/tr/fulltext/u2/a299207.pdf#page=218},\n\turldate = {2020-05-15},\n\tauthor = {Rybicki, Nancy and Carter, Virginia},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region.\n \n \n \n\n\n \n Lefcheck, J. S.; Orth, R. J.; Dennison, W. C.; Wilcox, D. J.; Murphy, R. R.; Keisman, J.; Gurbisz, C.; Hannam, M.; Brooke Landry, J.; Moore, K. A.; Patrick, C. J.; Testa, J.; Weller, D. E.; and Batiuk, R. A.\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences of the United States of America. 2018.\n \n\n\n\n
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@article{lefcheck_long-term_2018,\n\ttitle = {Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region},\n\tdoi = {10.1073/pnas.1715798115},\n\tabstract = {Humans strongly impact the dynamics of coastal systems, yet surprisingly few studies mechanistically link management of anthropogenic stressors and successful restoration of nearshore habitats over large spatial and temporal scales. Such examples are sorely needed to ensure the success of ecosystem restoration efforts worldwide. Here, we unite 30 consecutive years of watershed modeling, biogeochemical data, and comprehensive aerial surveys of Chesapeake Bay, United States to quantify the cascading effects of anthropogenic impacts on submersed aquatic vegetation (SAV), an ecologically and economically valuable habitat. We employ structural equation models to link land use change to higher nutrient loads, which in turn reduce SAV cover through multiple, independent pathways. We also show through our models that high biodiversity of SAV consistently promotes cover, an unexpected finding that corroborates emerging evidence from other terrestrial and marine systems. Due to sustained management actions that have reduced nitrogen concentrations in Chesapeake Bay by 23\\% since 1984, SAV has regained 17,000 ha to achieve its highest cover in almost half a century. Our study empirically demonstrates that nutrient reductions and biodiversity conservation are effective strategies to aid the successful recovery of degraded systems at regional scales, a finding which is highly relevant to the utility of environmental management programs worldwide.},\n\tjournal = {Proceedings of the National Academy of Sciences of the United States of America},\n\tauthor = {Lefcheck, Jonathan S. and Orth, Robert J. and Dennison, William C. and Wilcox, David J. and Murphy, Rebecca R. and Keisman, Jennifer and Gurbisz, Cassie and Hannam, Michael and Brooke Landry, J. and Moore, Kenneth A. and Patrick, Christopher J. and Testa, Jeremy and Weller, Donald E. and Batiuk, Richard A.},\n\tyear = {2018},\n\tpmid = {29507225},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n
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\n Humans strongly impact the dynamics of coastal systems, yet surprisingly few studies mechanistically link management of anthropogenic stressors and successful restoration of nearshore habitats over large spatial and temporal scales. Such examples are sorely needed to ensure the success of ecosystem restoration efforts worldwide. Here, we unite 30 consecutive years of watershed modeling, biogeochemical data, and comprehensive aerial surveys of Chesapeake Bay, United States to quantify the cascading effects of anthropogenic impacts on submersed aquatic vegetation (SAV), an ecologically and economically valuable habitat. We employ structural equation models to link land use change to higher nutrient loads, which in turn reduce SAV cover through multiple, independent pathways. We also show through our models that high biodiversity of SAV consistently promotes cover, an unexpected finding that corroborates emerging evidence from other terrestrial and marine systems. Due to sustained management actions that have reduced nitrogen concentrations in Chesapeake Bay by 23% since 1984, SAV has regained 17,000 ha to achieve its highest cover in almost half a century. Our study empirically demonstrates that nutrient reductions and biodiversity conservation are effective strategies to aid the successful recovery of degraded systems at regional scales, a finding which is highly relevant to the utility of environmental management programs worldwide.\n
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\n \n\n \n \n \n \n \n Submersed aquatic vegetation in chesapeake bay: Sentinel species in a changing world.\n \n \n \n\n\n \n Orth, R. J.; Dennison, W. C.; Lefcheck, J. S.; Gurbisz, C.; Hannam, M.; Keisman, J.; Landry, J. B.; Moore, K. A.; Murphy, R. R.; Patrick, C. J.; Testa, J.; Weller, D. E.; and Wilcox, D. J.\n\n\n \n\n\n\n 2017.\n Publication Title: BioScience\n\n\n\n
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@book{orth_submersed_2017-1,\n\ttitle = {Submersed aquatic vegetation in chesapeake bay: {Sentinel} species in a changing world},\n\tabstract = {Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.},\n\tauthor = {Orth, Robert J. and Dennison, William C. and Lefcheck, Jonathan S. and Gurbisz, Cassie and Hannam, Michael and Keisman, Jennifer and Landry, J. Brooke and Moore, Kenneth A. and Murphy, Rebecca R. and Patrick, Christopher J. and Testa, Jeremy and Weller, Donald E. and Wilcox, David J.},\n\tyear = {2017},\n\tdoi = {10.1093/biosci/bix058},\n\tnote = {Publication Title: BioScience},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.\n
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\n \n\n \n \n \n \n \n The Relationship Between Shoreline Armoring and Adjacent Submerged Aquatic Vegetation in Chesapeake Bay and Nearby Atlantic Coastal Bays.\n \n \n \n\n\n \n Patrick, C. J.; Weller, D. E.; and Ryder, M.\n\n\n \n\n\n\n Estuaries and Coasts. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{patrick_relationship_2016-1,\n\ttitle = {The {Relationship} {Between} {Shoreline} {Armoring} and {Adjacent} {Submerged} {Aquatic} {Vegetation} in {Chesapeake} {Bay} and {Nearby} {Atlantic} {Coastal} {Bays}},\n\tdoi = {10.1007/s12237-015-9970-2},\n\tabstract = {Shoreline armoring is an ancient and globally used engineering strategy to prevent shoreline erosion along marine, estuarine, and freshwater coastlines. Armoring alters the land water interface and has the potential to affect nearshore submerged aquatic vegetation (SAV) by changing nearshore hydrology, morphology, water clarity, and sediment composition. We quantified the relationships between the condition (bulkhead, riprap, or natural) of individual shoreline segments and three measures of directly adjacent SAV (the area of potential SAV habitat, the area occupied by SAV, and the proportion of potential habitat area that was occupied) in the Chesapeake Bay and nearby Atlantic coastal bays. Bulkhead had negative relationships with SAV in the polyhaline and mesohaline zones. Salinity and watershed land cover significantly modified the effect of shoreline armoring on nearshore SAV beds, and the effects of armoring were strongest in polyhaline subestuaries with forested watersheds. In high salinity systems, distance from shore modified the relationship between shoreline and SAV. The negative relationship between bulkhead and SAV was greater further off shore. By using individual shoreline segments as the study units, our analysis separated the effects of armoring and land cover, which were confounded in previous analyses that quantified average armoring and SAV abundance for much larger study units (subestuaries). Our findings suggest that redesigning or removing shoreline armoring structures may benefit nearshore SAV in some settings. Because armoring is ubiquitous, such information can inform efforts to reverse the global decline in SAV and the loss of the ecosystem services that SAV provides.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Patrick, Christopher J. and Weller, Donald E. and Ryder, Micah},\n\tyear = {2016},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Shoreline armoring is an ancient and globally used engineering strategy to prevent shoreline erosion along marine, estuarine, and freshwater coastlines. Armoring alters the land water interface and has the potential to affect nearshore submerged aquatic vegetation (SAV) by changing nearshore hydrology, morphology, water clarity, and sediment composition. We quantified the relationships between the condition (bulkhead, riprap, or natural) of individual shoreline segments and three measures of directly adjacent SAV (the area of potential SAV habitat, the area occupied by SAV, and the proportion of potential habitat area that was occupied) in the Chesapeake Bay and nearby Atlantic coastal bays. Bulkhead had negative relationships with SAV in the polyhaline and mesohaline zones. Salinity and watershed land cover significantly modified the effect of shoreline armoring on nearshore SAV beds, and the effects of armoring were strongest in polyhaline subestuaries with forested watersheds. In high salinity systems, distance from shore modified the relationship between shoreline and SAV. The negative relationship between bulkhead and SAV was greater further off shore. By using individual shoreline segments as the study units, our analysis separated the effects of armoring and land cover, which were confounded in previous analyses that quantified average armoring and SAV abundance for much larger study units (subestuaries). Our findings suggest that redesigning or removing shoreline armoring structures may benefit nearshore SAV in some settings. Because armoring is ubiquitous, such information can inform efforts to reverse the global decline in SAV and the loss of the ecosystem services that SAV provides.\n
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\n \n\n \n \n \n \n \n Trophic transfer in seagrass systems: Estimating seasonal production of an abundant seagrass fish, Bairdiella chrysoura, in lower Chesapeake Bay.\n \n \n \n\n\n \n Sobocinski, K. L.; and Latour, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 523: 157–174. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{sobocinski_trophic_2015,\n\ttitle = {Trophic transfer in seagrass systems: {Estimating} seasonal production of an abundant seagrass fish, {Bairdiella} chrysoura, in lower {Chesapeake} {Bay}},\n\tvolume = {523},\n\tdoi = {10.3354/meps11163},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Sobocinski, Kathryn L. and Latour, Robert J.},\n\tyear = {2015},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {157--174},\n}\n\n
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\n \n\n \n \n \n \n \n Interannual variation in submerged aquatic vegetation and its relationship to water quality in subestuaries of Chesapeake Bay.\n \n \n \n\n\n \n Patrick, C. J.; and Weller, D. E.\n\n\n \n\n\n\n Marine Ecology Progress Series, 537: 121–135. 2015.\n \n\n\n\n
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@article{patrick_interannual_2015,\n\ttitle = {Interannual variation in submerged aquatic vegetation and its relationship to water quality in subestuaries of {Chesapeake} {Bay}},\n\tvolume = {537},\n\tdoi = {10.3354/meps11412},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Patrick, Christopher J. and Weller, Donald E.},\n\tyear = {2015},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {121--135},\n}\n\n
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\n \n\n \n \n \n \n \n Critical Habitats and Stock Assessment: Age-Specific Bias in the Chesapeake Bay Blue Crab Population Survey.\n \n \n \n\n\n \n Ralph, G. M; and Lipcius, R. N\n\n\n \n\n\n\n Transactions of the American Fisheries Society, 143(4): 889–898. 2014.\n Number: 4 ISBN: 0002-8487\n\n\n\n
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@article{ralph_critical_2014,\n\ttitle = {Critical {Habitats} and {Stock} {Assessment}: {Age}-{Specific} {Bias} in the {Chesapeake} {Bay} {Blue} {Crab} {Population} {Survey}},\n\tvolume = {143},\n\tdoi = {10.1080/00028487.2014.901247},\n\tnumber = {4},\n\tjournal = {Transactions of the American Fisheries Society},\n\tauthor = {Ralph, Gina M and Lipcius, Romuald N},\n\tyear = {2014},\n\tnote = {Number: 4\nISBN: 0002-8487},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {889--898},\n}\n\n
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\n \n\n \n \n \n \n \n Effects of Shoreline Alteration and Other Stressors on Submerged Aquatic Vegetation in Subestuaries of Chesapeake Bay and the Mid-Atlantic Coastal Bays.\n \n \n \n\n\n \n Patrick, C. J.; Weller, D. E.; Li, X.; and Ryder, M.\n\n\n \n\n\n\n Estuaries and Coasts, 37(6): 1516–1531. 2014.\n Number: 6\n\n\n\n
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@article{patrick_effects_2014,\n\ttitle = {Effects of {Shoreline} {Alteration} and {Other} {Stressors} on {Submerged} {Aquatic} {Vegetation} in {Subestuaries} of {Chesapeake} {Bay} and the {Mid}-{Atlantic} {Coastal} {Bays}},\n\tvolume = {37},\n\tdoi = {10.1007/s12237-014-9768-7},\n\tnumber = {6},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Patrick, Christopher J. and Weller, Donald E. and Li, Xuyong and Ryder, Micah},\n\tyear = {2014},\n\tnote = {Number: 6},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {1516--1531},\n}\n\n
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\n \n\n \n \n \n \n \n \n Shoreline Energy and Sea Level Dynamics in Lower Chesapeake Bay: History and Patterns.\n \n \n \n \n\n\n \n Varnell, L. M.\n\n\n \n\n\n\n Estuaries and Coasts, 37(2): 508–523. 2013.\n Number: 2\n\n\n\n
\n\n\n\n \n \n \"ShorelinePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{varnell_shoreline_2013,\n\ttitle = {Shoreline {Energy} and {Sea} {Level} {Dynamics} in {Lower} {Chesapeake} {Bay}: {History} and {Patterns}},\n\tvolume = {37},\n\turl = {http://link.springer.com/10.1007/s12237-013-9672-6},\n\tdoi = {10.1007/s12237-013-9672-6},\n\tnumber = {2},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Varnell, Lyle M.},\n\tyear = {2013},\n\tnote = {Number: 2},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {508--523},\n}\n\n
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\n \n\n \n \n \n \n \n Sediment Accumulation Rates and Submersed Aquatic Vegetation (SAV) Distributions in the Mesohaline Chesapeake Bay, USA.\n \n \n \n\n\n \n Palinkas, C. M.; and Koch, E. W.\n\n\n \n\n\n\n Estuaries and Coasts. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{palinkas_sediment_2012,\n\ttitle = {Sediment {Accumulation} {Rates} and {Submersed} {Aquatic} {Vegetation} ({SAV}) {Distributions} in the {Mesohaline} {Chesapeake} {Bay}, {USA}},\n\tdoi = {10.1007/s12237-012-9542-7},\n\tabstract = {This study assesses spatial and temporal sedimentological trends in four mesohaline Chesapeake Bay submersed aquatic vegetation (SAV) habitats, two with persistent SAV beds and two with ephemeral SAV beds, to determine their relationship to current and historical sediment characteristics-grain size, organic content, and accumulation rates. In general, grain size is similar among all sites, and subsurface sediment differs from surficial sediment only at one site where a thin surficial sand layer (∼2-3 cm) is present. This thin sand layer is not completely preserved in the longer-term sedimentary record even though it is critical to determining whether the sediment is suitable for SAV. Evidence for nearshore fining, similar to that observed in the deeper waters of the Bay, is present at the site where the shoreline has been hardened suggesting that locations with hardened shorelines limit exchange of coarser (sandy) material between the shore and nearshore environments. Whether the fining trend will continue to a point at which the sediment will become unsuitable for SAV in the future or whether some new type of equilibrium will be reached cannot be addressed with our data. Instead, our data suggest that SAV presence/absence is related to changes in sedimentary characteristics-persistent beds have relatively steady sediment composition, while ephemeral beds have finer sediments due to reduced sand input. Additionally, sediment accumulation rates in the persistent beds are ∼9 mm/year, whereas rates in the ephemeral beds are ∼3 mm/year. Thus, the ephemeral sites highlight two potential sedimentary controls on SAV distribution: the presence of a sufficiently thick surficial sand layer as previously postulated by Wicks (2005) and accumulation rates high enough to bury seeds prior to germination and/or keep up with sea-level rise. © 2012 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Palinkas, Cindy M. and Koch, Evamaria W.},\n\tyear = {2012},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n This study assesses spatial and temporal sedimentological trends in four mesohaline Chesapeake Bay submersed aquatic vegetation (SAV) habitats, two with persistent SAV beds and two with ephemeral SAV beds, to determine their relationship to current and historical sediment characteristics-grain size, organic content, and accumulation rates. In general, grain size is similar among all sites, and subsurface sediment differs from surficial sediment only at one site where a thin surficial sand layer (∼2-3 cm) is present. This thin sand layer is not completely preserved in the longer-term sedimentary record even though it is critical to determining whether the sediment is suitable for SAV. Evidence for nearshore fining, similar to that observed in the deeper waters of the Bay, is present at the site where the shoreline has been hardened suggesting that locations with hardened shorelines limit exchange of coarser (sandy) material between the shore and nearshore environments. Whether the fining trend will continue to a point at which the sediment will become unsuitable for SAV in the future or whether some new type of equilibrium will be reached cannot be addressed with our data. Instead, our data suggest that SAV presence/absence is related to changes in sedimentary characteristics-persistent beds have relatively steady sediment composition, while ephemeral beds have finer sediments due to reduced sand input. Additionally, sediment accumulation rates in the persistent beds are ∼9 mm/year, whereas rates in the ephemeral beds are ∼3 mm/year. Thus, the ephemeral sites highlight two potential sedimentary controls on SAV distribution: the presence of a sufficiently thick surficial sand layer as previously postulated by Wicks (2005) and accumulation rates high enough to bury seeds prior to germination and/or keep up with sea-level rise. © 2012 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Influences of Salinity and Light Availability on Abundance and Distribution of Tidal Freshwater and Oligohaline Submersed Aquatic Vegetation.\n \n \n \n\n\n \n Shields, E. C.; Moore, K. A.; and Parrish, D. B.\n\n\n \n\n\n\n Estuaries and Coasts, 35(2): 515–526. 2012.\n Number: 2\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{shields_influences_2012,\n\ttitle = {Influences of {Salinity} and {Light} {Availability} on {Abundance} and {Distribution} of {Tidal} {Freshwater} and {Oligohaline} {Submersed} {Aquatic} {Vegetation}},\n\tvolume = {35},\n\tdoi = {10.1007/s12237-011-9460-0},\n\tabstract = {Submersed aquatic vegetation (SAV) communities have undergone declines worldwide, exposing them to invasions from non-native species. Over the past decade, the invasive species Hydrilla verticillata has been documented in several tributaries of the lower Chesapeake Bay, Virginia. We used annual aerial mapping surveys from 1998 to 2007, integrated with spatial analyses of water quality data, to analyze the patterns and rates of change of a H. verticillata-dominated SAV community and relate them to varying salinity and light conditions. Periods of declining SAV coverage corresponded to periods where salinities exceeded 7 and early growing season (April to May) Secchi depths were {\\textbackslash}textless0.4 m. Increases were driven by the expansion of H. verticillata along with several other species into the upper estuary, where some areas experienced an 80\\% increase in cover. Field investigations revealed H. verticillata dominance to be limited to the upper estuary where total suspended solid concentrations during the early growing season were {\\textbackslash}textless15 mg l−1 and salinity remained {\\textbackslash}textless3. The effect of poor early growing season water clarity on annual SAV growth highlights the importance of water quality during this critical life stage. Periods of low clarity combined with periodic salinity intrusions may limit the dominance of H. verticillata in these types of estuarine systems. This study shows the importance of the use of these types of biologically relevant episodic events to supplement seasonal habitat requirements and also provides evidence for the potential important role of invasive species in SAV community recovery.},\n\tnumber = {2},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Shields, Erin C. and Moore, Kenneth A. and Parrish, David B.},\n\tyear = {2012},\n\tnote = {Number: 2},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {515--526},\n}\n\n
\n
\n\n\n
\n Submersed aquatic vegetation (SAV) communities have undergone declines worldwide, exposing them to invasions from non-native species. Over the past decade, the invasive species Hydrilla verticillata has been documented in several tributaries of the lower Chesapeake Bay, Virginia. We used annual aerial mapping surveys from 1998 to 2007, integrated with spatial analyses of water quality data, to analyze the patterns and rates of change of a H. verticillata-dominated SAV community and relate them to varying salinity and light conditions. Periods of declining SAV coverage corresponded to periods where salinities exceeded 7 and early growing season (April to May) Secchi depths were \\textless0.4 m. Increases were driven by the expansion of H. verticillata along with several other species into the upper estuary, where some areas experienced an 80% increase in cover. Field investigations revealed H. verticillata dominance to be limited to the upper estuary where total suspended solid concentrations during the early growing season were \\textless15 mg l−1 and salinity remained \\textless3. The effect of poor early growing season water clarity on annual SAV growth highlights the importance of water quality during this critical life stage. Periods of low clarity combined with periodic salinity intrusions may limit the dominance of H. verticillata in these types of estuarine systems. This study shows the importance of the use of these types of biologically relevant episodic events to supplement seasonal habitat requirements and also provides evidence for the potential important role of invasive species in SAV community recovery.\n
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\n \n\n \n \n \n \n \n Spatial Patterns in Water Quality Associated with Submersed Plant Beds.\n \n \n \n\n\n \n Gruber, R. K.; Hinkle, D. C.; and Kemp, W. M.\n\n\n \n\n\n\n Estuaries and Coasts. 2011.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{gruber_spatial_2011,\n\ttitle = {Spatial {Patterns} in {Water} {Quality} {Associated} with {Submersed} {Plant} {Beds}},\n\tdoi = {10.1007/s12237-010-9368-0},\n\tabstract = {This study describes the influence of submersed plant beds on spatial distributions of key water quality variables. An on-board flow-through water sampling system was used to investigate patterns in turbidity, chlorophyll-a, temperature, dissolved oxygen, and pH across a robust stand of the submersed plant Stuckenia pectinata. Spatially interpolated maps show that water quality conditions were significantly altered within this plant bed, especially during months of peak biomass, and that reduction of suspended particles focused at the bed's edge. Comparison with a suite of submersed plant beds indicated that patterns were related to canopy height, shoot density, and cross-shore bed width. Wide and dense stands with tall canopies showed reduced turbidity and increased light penetration, while smaller sparser beds often showed elevated within-bed turbidity. These results suggest that bed effects on water quality conditions vary seasonally with plant canopy architecture and bed size, providing tentative guidelines for restoring self-sustaining beds. © 2011 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Gruber, Renee K. and Hinkle, Deborah C. and Kemp, W. Michael},\n\tyear = {2011},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n This study describes the influence of submersed plant beds on spatial distributions of key water quality variables. An on-board flow-through water sampling system was used to investigate patterns in turbidity, chlorophyll-a, temperature, dissolved oxygen, and pH across a robust stand of the submersed plant Stuckenia pectinata. Spatially interpolated maps show that water quality conditions were significantly altered within this plant bed, especially during months of peak biomass, and that reduction of suspended particles focused at the bed's edge. Comparison with a suite of submersed plant beds indicated that patterns were related to canopy height, shoot density, and cross-shore bed width. Wide and dense stands with tall canopies showed reduced turbidity and increased light penetration, while smaller sparser beds often showed elevated within-bed turbidity. These results suggest that bed effects on water quality conditions vary seasonally with plant canopy architecture and bed size, providing tentative guidelines for restoring self-sustaining beds. © 2011 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Extinction risk assessment of the world's seagrass species.\n \n \n \n\n\n \n Short, F. T.; Polidoro, B.; Livingstone, S. R.; Carpenter, K. E.; Bandeira, S.; Bujang, J. S.; Calumpong, H. P.; Carruthers, T. J.; Coles, R. G.; Dennison, W. C.; Erftemeijer, P. L.; Fortes, M. D.; Freeman, A. S.; Jagtap, T. G.; Kamal, A. H. M.; Kendrick, G. A.; Judson Kenworthy, W.; La Nafie, Y. A.; Nasution, I. M.; Orth, R. J.; Prathep, A.; Sanciangco, J. C.; van Tussenbroek, B.; Vergara, S. G.; Waycott, M.; and Zieman, J. C.\n\n\n \n\n\n\n Biological Conservation. 2011.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{short_extinction_2011,\n\ttitle = {Extinction risk assessment of the world's seagrass species},\n\tdoi = {10.1016/j.biocon.2011.04.010},\n\tabstract = {Seagrasses, a functional group of marine flowering plants rooted in the world's coastal oceans, support marine food webs and provide essential habitat for many coastal species, playing a critical role in the equilibrium of coastal ecosystems and human livelihoods. For the first time, the probability of extinction is determined for the world's seagrass species under the Categories and Criteria of the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. Several studies have indicated that seagrass habitat is declining worldwide. Our focus is to determine the risk of extinction for individual seagrass species, a 4-year process involving seagrass experts internationally, compilation of data on species' status, populations, and distribution, and review of the biology and ecology of each of the world's seagrass species. Ten seagrass species are at elevated risk of extinction (14\\% of all seagrass species), with three species qualifying as Endangered. Seagrass species loss and degradation of seagrass biodiversity will have serious repercussions for marine biodiversity and the human populations that depend upon the resources and ecosystem services that seagrasses provide. © 2011 Elsevier Ltd.},\n\tjournal = {Biological Conservation},\n\tauthor = {Short, Frederick T. and Polidoro, Beth and Livingstone, Suzanne R. and Carpenter, Kent E. and Bandeira, Salomão and Bujang, Japar Sidik and Calumpong, Hilconida P. and Carruthers, Tim J.B. and Coles, Robert G. and Dennison, William C. and Erftemeijer, Paul L.A. and Fortes, Miguel D. and Freeman, Aaren S. and Jagtap, T. G. and Kamal, Abu Hena M. and Kendrick, Gary A. and Judson Kenworthy, W. and La Nafie, Yayu A. and Nasution, Ichwan M. and Orth, Robert J. and Prathep, Anchana and Sanciangco, Jonnell C. and van Tussenbroek, Brigitta and Vergara, Sheila G. and Waycott, Michelle and Zieman, Joseph C.},\n\tyear = {2011},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Seagrasses, a functional group of marine flowering plants rooted in the world's coastal oceans, support marine food webs and provide essential habitat for many coastal species, playing a critical role in the equilibrium of coastal ecosystems and human livelihoods. For the first time, the probability of extinction is determined for the world's seagrass species under the Categories and Criteria of the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. Several studies have indicated that seagrass habitat is declining worldwide. Our focus is to determine the risk of extinction for individual seagrass species, a 4-year process involving seagrass experts internationally, compilation of data on species' status, populations, and distribution, and review of the biology and ecology of each of the world's seagrass species. Ten seagrass species are at elevated risk of extinction (14% of all seagrass species), with three species qualifying as Endangered. Seagrass species loss and degradation of seagrass biodiversity will have serious repercussions for marine biodiversity and the human populations that depend upon the resources and ecosystem services that seagrasses provide. © 2011 Elsevier Ltd.\n
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\n \n\n \n \n \n \n \n Eelgrass (Zostera marina L.) in the Chesapeake Bay region of mid-Atlantic coast of the USA: Challenges in conservation and restoration.\n \n \n \n\n\n \n Orth, R. J.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Estuaries and Coasts. 2010.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_eelgrass_2010,\n\ttitle = {Eelgrass ({Zostera} marina {L}.) in the {Chesapeake} {Bay} region of mid-{Atlantic} coast of the {USA}: {Challenges} in conservation and restoration},\n\tdoi = {10.1007/s12237-009-9234-0},\n\tabstract = {Decreases in seagrass abundance reported from numerous locations around the world suggest that seagrass are facing a global crisis. Declining water quality has been identified as the leading cause for most losses. Increased public awareness is leading to expanded efforts for conservation and restoration. Here, we report on abundance patterns and environmental issues facing eelgrass (Zostera marina), the dominant seagrass species in the Chesapeake Bay region in the mid-Atlantic coast of the USA, and describe efforts to promote its protection and restoration. Eelgrass beds in Chesapeake Bay and Chincoteague Bay, which had started to recover from earlier diebacks, have shown a downward trend in the last 5-10 years, while eelgrass beds in the Virginia coastal bays have substantially increased in abundance during this same time period. Declining water quality appears to be the primary reason for the decreased abundance, but a recent baywide dieback in 2005 was associated with higher than usual summer water temperatures along with poor water clarity. The success of eelgrass in the Virginia coastal bays has been attributed, in part, to slightly cooler water due to their proximity to the Atlantic Ocean. A number of policies and regulations have been adopted in this region since 1983 aimed at protecting and restoring both habitat and water quality. Eelgrass abundance is now one of the criteria for assessing attainment of water clarity goals in this region. Numerous transplant projects have been aimed at restoring eelgrass but most have not succeeded beyond 1 to 2 years. A notable exception is the large-scale restoration effort in the Virginia coastal bays, where seeds distributed beginning in 2001 has initiated an expanding recovery process. Our research on eelgrass abundance patterns in the Chesapeake Bay region and the processes contributing to these patterns have provided a scientific background for management strategies for the protection and restoration of eelgrass and insights into the causes of success and failure of restoration efforts that may have applications to other seagrass systems. © Coastal and Estuarine Research Federation 2009.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Orth, Robert J. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tyear = {2010},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Decreases in seagrass abundance reported from numerous locations around the world suggest that seagrass are facing a global crisis. Declining water quality has been identified as the leading cause for most losses. Increased public awareness is leading to expanded efforts for conservation and restoration. Here, we report on abundance patterns and environmental issues facing eelgrass (Zostera marina), the dominant seagrass species in the Chesapeake Bay region in the mid-Atlantic coast of the USA, and describe efforts to promote its protection and restoration. Eelgrass beds in Chesapeake Bay and Chincoteague Bay, which had started to recover from earlier diebacks, have shown a downward trend in the last 5-10 years, while eelgrass beds in the Virginia coastal bays have substantially increased in abundance during this same time period. Declining water quality appears to be the primary reason for the decreased abundance, but a recent baywide dieback in 2005 was associated with higher than usual summer water temperatures along with poor water clarity. The success of eelgrass in the Virginia coastal bays has been attributed, in part, to slightly cooler water due to their proximity to the Atlantic Ocean. A number of policies and regulations have been adopted in this region since 1983 aimed at protecting and restoring both habitat and water quality. Eelgrass abundance is now one of the criteria for assessing attainment of water clarity goals in this region. Numerous transplant projects have been aimed at restoring eelgrass but most have not succeeded beyond 1 to 2 years. A notable exception is the large-scale restoration effort in the Virginia coastal bays, where seeds distributed beginning in 2001 has initiated an expanding recovery process. Our research on eelgrass abundance patterns in the Chesapeake Bay region and the processes contributing to these patterns have provided a scientific background for management strategies for the protection and restoration of eelgrass and insights into the causes of success and failure of restoration efforts that may have applications to other seagrass systems. © Coastal and Estuarine Research Federation 2009.\n
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\n \n\n \n \n \n \n \n Long-Term Trends of Water Quality and Biotic Metrics in Chesapeake Bay: 1986 to 2008.\n \n \n \n\n\n \n Williams, M. R.; Filoso, S.; Longstaff, B. J.; and Dennison, W. C.\n\n\n \n\n\n\n Estuaries and Coasts. 2010.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{williams_long-term_2010,\n\ttitle = {Long-{Term} {Trends} of {Water} {Quality} and {Biotic} {Metrics} in {Chesapeake} {Bay}: 1986 to 2008},\n\tdoi = {10.1007/s12237-010-9333-y},\n\tabstract = {We analyzed trends in a 23-year period of water quality and biotic data for Chesapeake Bay. Indicators were used to detect trends of improving and worsening environmental health in 15 regions and 70 segments of the bay and to assess the estuarine ecosystem's responses to reduced nutrient loading from point (i.e., sewage treatment facilities) and non-point (e.g., agricultural and urban land use) sources. Despite extensive restoration efforts, ecological health-related water quality (chlorophyll-a, dissolved oxygen, Secchi depth) and biotic (phytoplankton and benthic indices) metrics evaluated herein have generally shown little improvement (submerged aquatic vegetation was an exception), and water clarity and chlorophyll-a have considerably worsened since 1986. Nutrient and sediment inputs from higher-than-average annual flows after 1992 combined with those from highly developed Coastal Plain areas and compromised ecosystem resiliency are important factors responsible for worsening chlorophyll-a and Secchi depth trends in mesohaline and polyhaline zones from 1986 to 2008. © 2010 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Williams, Michael R. and Filoso, Solange and Longstaff, Benjamin J. and Dennison, William C.},\n\tyear = {2010},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n We analyzed trends in a 23-year period of water quality and biotic data for Chesapeake Bay. Indicators were used to detect trends of improving and worsening environmental health in 15 regions and 70 segments of the bay and to assess the estuarine ecosystem's responses to reduced nutrient loading from point (i.e., sewage treatment facilities) and non-point (e.g., agricultural and urban land use) sources. Despite extensive restoration efforts, ecological health-related water quality (chlorophyll-a, dissolved oxygen, Secchi depth) and biotic (phytoplankton and benthic indices) metrics evaluated herein have generally shown little improvement (submerged aquatic vegetation was an exception), and water clarity and chlorophyll-a have considerably worsened since 1986. Nutrient and sediment inputs from higher-than-average annual flows after 1992 combined with those from highly developed Coastal Plain areas and compromised ecosystem resiliency are important factors responsible for worsening chlorophyll-a and Secchi depth trends in mesohaline and polyhaline zones from 1986 to 2008. © 2010 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Long-term reductions in anthropogenic nutrients link to improvements in Chesapeake Bay habitat.\n \n \n \n\n\n \n Ruhl, H. a; and Rybicki, N. B\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences of the United States of America, 107(38): 16566–16570. 2010.\n Number: 38 ISBN: 1091-6490 (Electronic)${\\}backslash$r0027-8424 (Linking)\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{ruhl_long-term_2010,\n\ttitle = {Long-term reductions in anthropogenic nutrients link to improvements in {Chesapeake} {Bay} habitat.},\n\tvolume = {107},\n\tdoi = {10.1073/pnas.1003590107},\n\tabstract = {Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990-2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.},\n\tnumber = {38},\n\tjournal = {Proceedings of the National Academy of Sciences of the United States of America},\n\tauthor = {Ruhl, Henry a and Rybicki, Nancy B},\n\tyear = {2010},\n\tpmid = {20823243},\n\tnote = {Number: 38\nISBN: 1091-6490 (Electronic)\\${\\textbackslash}backslash\\$r0027-8424 (Linking)},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {16566--16570},\n}\n\n
\n
\n\n\n
\n Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990-2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Submerged Aquatic Vegetation of the York River.\n \n \n \n\n\n \n Moore, K. A.\n\n\n \n\n\n\n Journal of Coastal Research. 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_submerged_2009,\n\ttitle = {Submerged {Aquatic} {Vegetation} of the {York} {River}},\n\tdoi = {10.2112/1551-5036-57.sp1.50},\n\tabstract = {Submerged aquatic vegetation or SAV are important components of shallow\\${\\textbackslash}backslash\\$nwater areas of the York River estuary. The plants that comprise these\\${\\textbackslash}backslash\\$ncommunities are distributed in shallow water areas ({\\textbackslash}textless2m) along the\\${\\textbackslash}backslash\\$nestuary from polyhaline to Freshwater areas according to their\\${\\textbackslash}backslash\\$nindividual salinity tolerances. Eelgrass (Zostera marina) is the only\\${\\textbackslash}backslash\\$ntrue seagrass an is found only in the lower York River where salinities\\${\\textbackslash}backslash\\$naverage above 20 psu. It is a cool water species that decreases in\\${\\textbackslash}backslash\\$nabundance in the summer due to high water temperatures. SAV in this\\${\\textbackslash}backslash\\$nregion have declined precipitously from historical abundances due to\\${\\textbackslash}backslash\\$nexcessive levels of turbidity and nutrients. Infection of a marine slime\\${\\textbackslash}backslash\\$nmould-like protist, Labyrinthula. zosterae, also impacted this species\\${\\textbackslash}backslash\\$nin the 1930s, nearly decimating it from this area. Widgeon grass (Ruppia\\${\\textbackslash}backslash\\$nmaritima) co-occurs with eelgrass but can also grow in low salinity\\${\\textbackslash}backslash\\$nareas. Pondweeds (Potamogeton) and many other SAV species grow in both\\${\\textbackslash}backslash\\$nlow salinity and freshwater areas. Macroalgae or “seaweeds\\{”\\} are\\${\\textbackslash}backslash\\$ncurrently a minor component of SAV in the York River system. Several\\${\\textbackslash}backslash\\$nalgal genera common in the area include: Agardhiella, Ulva, Enteromorpha\\${\\textbackslash}backslash\\$nand Chara. While there has been a great deal learned through research\\${\\textbackslash}backslash\\$nand monitoring relative to SAV communities in the Chesapeake Bay, in\\${\\textbackslash}backslash\\$ngeneral, and the York River, in particular, more efforts are needed to\\${\\textbackslash}backslash\\$nadvance SAV protection and restoration to achieve the SAV restoration\\${\\textbackslash}backslash\\$ngoals. Research efforts are needed to further understand the\\${\\textbackslash}backslash\\$nrelationships between environmental conditions and SAV response and the\\${\\textbackslash}backslash\\$ninteractions between of various stressors on SAV Other areas for further\\${\\textbackslash}backslash\\$nresearch focus include investigations of the relationships between\\${\\textbackslash}backslash\\$nnatural and restored SAV growth, survival and bed persistence and\\${\\textbackslash}backslash\\$nbiological stresses including herbivory or secondary physical\\${\\textbackslash}backslash\\$ndisturbance through foraging, bioturbation or other activities. One\\${\\textbackslash}backslash\\$nimportant need is to quantify the short and long term relationships\\${\\textbackslash}backslash\\$nbetween SAV decline and recovery and climatic factors Such as storms,\\${\\textbackslash}backslash\\$ndroughts, and temperature extremes that may be influenced by climate\\${\\textbackslash}backslash\\$nchange.},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Moore, Kenneth A.},\n\tyear = {2009},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Submerged aquatic vegetation or SAV are important components of shallow${\\}backslash$nwater areas of the York River estuary. The plants that comprise these${\\}backslash$ncommunities are distributed in shallow water areas (\\textless2m) along the${\\}backslash$nestuary from polyhaline to Freshwater areas according to their${\\}backslash$nindividual salinity tolerances. Eelgrass (Zostera marina) is the only${\\}backslash$ntrue seagrass an is found only in the lower York River where salinities${\\}backslash$naverage above 20 psu. It is a cool water species that decreases in${\\}backslash$nabundance in the summer due to high water temperatures. SAV in this${\\}backslash$nregion have declined precipitously from historical abundances due to${\\}backslash$nexcessive levels of turbidity and nutrients. Infection of a marine slime${\\}backslash$nmould-like protist, Labyrinthula. zosterae, also impacted this species${\\}backslash$nin the 1930s, nearly decimating it from this area. Widgeon grass (Ruppia${\\}backslash$nmaritima) co-occurs with eelgrass but can also grow in low salinity${\\}backslash$nareas. Pondweeds (Potamogeton) and many other SAV species grow in both${\\}backslash$nlow salinity and freshwater areas. Macroalgae or “seaweeds\\”\\ are${\\}backslash$ncurrently a minor component of SAV in the York River system. Several${\\}backslash$nalgal genera common in the area include: Agardhiella, Ulva, Enteromorpha${\\}backslash$nand Chara. While there has been a great deal learned through research${\\}backslash$nand monitoring relative to SAV communities in the Chesapeake Bay, in${\\}backslash$ngeneral, and the York River, in particular, more efforts are needed to${\\}backslash$nadvance SAV protection and restoration to achieve the SAV restoration${\\}backslash$ngoals. Research efforts are needed to further understand the${\\}backslash$nrelationships between environmental conditions and SAV response and the${\\}backslash$ninteractions between of various stressors on SAV Other areas for further${\\}backslash$nresearch focus include investigations of the relationships between${\\}backslash$nnatural and restored SAV growth, survival and bed persistence and${\\}backslash$nbiological stresses including herbivory or secondary physical${\\}backslash$ndisturbance through foraging, bioturbation or other activities. One${\\}backslash$nimportant need is to quantify the short and long term relationships${\\}backslash$nbetween SAV decline and recovery and climatic factors Such as storms,${\\}backslash$ndroughts, and temperature extremes that may be influenced by climate${\\}backslash$nchange.\n
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\n \n\n \n \n \n \n \n Effects of sediment organic content and hydrodynamic conditions on the growth and distribution of Zostera marina.\n \n \n \n\n\n \n Wicks, E. C.; Koch, E. W.; O'Neil, J. M.; and Elliston, K.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{wicks_effects_2009,\n\ttitle = {Effects of sediment organic content and hydrodynamic conditions on the growth and distribution of {Zostera} marina},\n\tdoi = {10.3354/meps07885},\n\tabstract = {The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content {\\textbackslash}textgreater 4\\%, especially compared with areas with sediment organic content {\\textbackslash}textless 4\\%. In contrast, in a mesocosm experiment, Z. marina thrived in organic rich (4 to 6\\%) sediment, developing long leaves and disproportionately short roots. Such plants have high drag and low anchoring capacity. As a result, Z manna plants grown in organic rich sediment are more likely to be dislodged than are plants grown in organic poor sand. We hypothesize that when organic rich sediments are found in hydrodynamically active areas, a mismatch occurs between plant morphology and the physical environment, leading to the loss of seagrasses due to uprooting. Therefore, sediment organic content limitations in seagrass habitats need to be evaluated within the local hydrodynamic settings. Fine organic sediment may be less limiting to seagrasses in quiescent waters while sand with low organic content may be required for seagrass survival in hydrodynamically active areas. © Inter-Research 2009.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Wicks, E. Caroline and Koch, Evamaria W. and O'Neil, Judy M. and Elliston, Kahla},\n\tyear = {2009},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content \\textgreater 4%, especially compared with areas with sediment organic content \\textless 4%. In contrast, in a mesocosm experiment, Z. marina thrived in organic rich (4 to 6%) sediment, developing long leaves and disproportionately short roots. Such plants have high drag and low anchoring capacity. As a result, Z manna plants grown in organic rich sediment are more likely to be dislodged than are plants grown in organic poor sand. We hypothesize that when organic rich sediments are found in hydrodynamically active areas, a mismatch occurs between plant morphology and the physical environment, leading to the loss of seagrasses due to uprooting. Therefore, sediment organic content limitations in seagrass habitats need to be evaluated within the local hydrodynamic settings. Fine organic sediment may be less limiting to seagrasses in quiescent waters while sand with low organic content may be required for seagrass survival in hydrodynamically active areas. © Inter-Research 2009.\n
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\n \n\n \n \n \n \n \n Introduction to the Chesapeake Bay National Estuarine Research Reserve in Virginia.\n \n \n \n\n\n \n Reay, W. G.; and Moore, K. A.\n\n\n \n\n\n\n Journal of Coastal Research. 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{reay_introduction_2009,\n\ttitle = {Introduction to the {Chesapeake} {Bay} {National} {Estuarine} {Research} {Reserve} in {Virginia}},\n\tdoi = {10.2112/1551-5036-57.sp1.1},\n\tabstract = {Designated in 1991, CBNERRVA established a multi-component system along\\${\\textbackslash}backslash\\$nthe salinity gradient of the York River estuary that encompassed the\\${\\textbackslash}backslash\\$ndiverse collection of habitats found within the southern Chesapeake Bay\\${\\textbackslash}backslash\\$nsubregion. With its two principal tributaries, the Pamunkey and\\${\\textbackslash}backslash\\$nMattaponi Rivers, the York River is the Bay's fifth largest tributary\\${\\textbackslash}backslash\\$nill terms of flow and watershed area. The cork River estuary is\\${\\textbackslash}backslash\\$nclassified as a microtidal, partially mixed estuary. Tidal range varies\\${\\textbackslash}backslash\\$nfrom 0.7 in and at its mouth to over I m in the upper freshwater\\${\\textbackslash}backslash\\$ntributary reaches and salinity distribution ranges from tidal freshwater\\${\\textbackslash}backslash\\$nto polyhaline regimes. Land use is predominantly rural in nature with\\${\\textbackslash}backslash\\$nforest(61\\%) and agricultural lands (21\\%) being (fie dominant land\\${\\textbackslash}backslash\\$ncover; wetlands comprise approximately 7\\% of the basins area. Reserve\\${\\textbackslash}backslash\\$ncomponents include: (1) Goodwin Islands (148 ha), an archipelago of\\${\\textbackslash}backslash\\$npolyhaline salt-marsh islands surrounded by inter-tidal flats, extensive\\${\\textbackslash}backslash\\$nsubmerged aquatic vegetation beds, and shallow open estuarine waters\\${\\textbackslash}backslash\\$nnear mouth of the York River; (2) Catlett Islands (220 ha), Consisting\\${\\textbackslash}backslash\\$nof multiple parallel ridges of forested wetland hammocks,\\${\\textbackslash}backslash\\$nmaritime-forest uplands, and emergent mesohaline salt marshes;\\${\\textbackslash}backslash\\$n(3)Taskinas Creek (433 ha), containing non-tidal feeder streams that\\${\\textbackslash}backslash\\$ndrain oak-hickory forests, maple-gum-ash swamps and freshwater marshes\\${\\textbackslash}backslash\\$nwhich transition into tidal oligo an(] mesohaline salt marshes; and (4)\\${\\textbackslash}backslash\\$nSweet Hall Marsh (443 ha), an extensive tidal freshwater-oligohaline\\${\\textbackslash}backslash\\$nmarsh ecosystem located in the Pamunkey River, one of two major\\${\\textbackslash}backslash\\$ntributaries of the York River. CBNERRVA manages these reserves to\\${\\textbackslash}backslash\\$nsupport informed management. of coastal resources by supporting research\\${\\textbackslash}backslash\\$nthat advances the scientific understanding of watershed and estuarine\\${\\textbackslash}backslash\\$nsystems, highlighting proper stewardship of coastal resources, and\\${\\textbackslash}backslash\\$nimproving general public and professional literacy through education and\\${\\textbackslash}backslash\\$ntraining programs.},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Reay, William G. and Moore, Kenneth A.},\n\tyear = {2009},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Designated in 1991, CBNERRVA established a multi-component system along${\\}backslash$nthe salinity gradient of the York River estuary that encompassed the${\\}backslash$ndiverse collection of habitats found within the southern Chesapeake Bay${\\}backslash$nsubregion. With its two principal tributaries, the Pamunkey and${\\}backslash$nMattaponi Rivers, the York River is the Bay's fifth largest tributary${\\}backslash$nill terms of flow and watershed area. The cork River estuary is${\\}backslash$nclassified as a microtidal, partially mixed estuary. Tidal range varies${\\}backslash$nfrom 0.7 in and at its mouth to over I m in the upper freshwater${\\}backslash$ntributary reaches and salinity distribution ranges from tidal freshwater${\\}backslash$nto polyhaline regimes. Land use is predominantly rural in nature with${\\}backslash$nforest(61%) and agricultural lands (21%) being (fie dominant land${\\}backslash$ncover; wetlands comprise approximately 7% of the basins area. Reserve${\\}backslash$ncomponents include: (1) Goodwin Islands (148 ha), an archipelago of${\\}backslash$npolyhaline salt-marsh islands surrounded by inter-tidal flats, extensive${\\}backslash$nsubmerged aquatic vegetation beds, and shallow open estuarine waters${\\}backslash$nnear mouth of the York River; (2) Catlett Islands (220 ha), Consisting${\\}backslash$nof multiple parallel ridges of forested wetland hammocks,${\\}backslash$nmaritime-forest uplands, and emergent mesohaline salt marshes;${\\}backslash$n(3)Taskinas Creek (433 ha), containing non-tidal feeder streams that${\\}backslash$ndrain oak-hickory forests, maple-gum-ash swamps and freshwater marshes${\\}backslash$nwhich transition into tidal oligo an(] mesohaline salt marshes; and (4)${\\}backslash$nSweet Hall Marsh (443 ha), an extensive tidal freshwater-oligohaline${\\}backslash$nmarsh ecosystem located in the Pamunkey River, one of two major${\\}backslash$ntributaries of the York River. CBNERRVA manages these reserves to${\\}backslash$nsupport informed management. of coastal resources by supporting research${\\}backslash$nthat advances the scientific understanding of watershed and estuarine${\\}backslash$nsystems, highlighting proper stewardship of coastal resources, and${\\}backslash$nimproving general public and professional literacy through education and${\\}backslash$ntraining programs.\n
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\n \n\n \n \n \n \n \n Accelerating loss of seagrasses across the globe threatens coastal ecosystems.\n \n \n \n\n\n \n 'Waycott, M.; Duarte, C. M.; Carruthers, T. J.; Orth, R. J.; Dennison, W. C.; Olyarnik, S.; Calladine, A.; Fourqurean, J. W.; Heck, K. L.; Hughes, A. R.; Kendrick, G. A.; Kenworthy, W. J.; Short, F. T.; and Williams, S. L.\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences of the United States of America. 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{waycott_accelerating_2009,\n\ttitle = {Accelerating loss of seagrasses across the globe threatens coastal ecosystems},\n\tdoi = {10.1073/pnas.0905620106},\n\tabstract = {Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated \\$1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 km2yr-1since 1980 and that 29\\% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9\\% yr-1before 1940 to 7\\% yr-1since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth.},\n\tjournal = {Proceedings of the National Academy of Sciences of the United States of America},\n\tauthor = {'Waycott, Michelle and Duarte, Carlos M. and Carruthers, Tim J.B. and Orth, Robert J. and Dennison, William C. and Olyarnik, Suzanne and Calladine, Ainsley and Fourqurean, James W. and Heck, Kenneth L. and Hughes, A. Randall and Kendrick, Gary A. and Kenworthy, W. Judson and Short, Frederick T. and Williams, Susan L.},\n\tyear = {2009},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 km2yr-1since 1980 and that 29% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9% yr-1before 1940 to 7% yr-1since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth.\n
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\n \n\n \n \n \n \n \n Paleoecology and ecosystem restoration: case studies from Chesapeake Bay and the Florida Everglades.\n \n \n \n\n\n \n Willard, D a; and Cronin, T M\n\n\n \n\n\n\n Frontiers in Ecology and the Environment, 5(9): 491–498. 2007.\n Number: 9 ISBN: 1540-9295\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{willard_paleoecology_2007,\n\ttitle = {Paleoecology and ecosystem restoration: case studies from {Chesapeake} {Bay} and the {Florida} {Everglades}},\n\tvolume = {5},\n\tdoi = {10.1890/070015},\n\tabstract = {Climate extremes that cause droughts, floods, or large temperature fluctuations can complicate ecosystem restoration efforts focused on local and regional human disturbance. Restoration targets are often based primarily on monitoring data and modeling simulations, which provide information on species' short-term response to disturbance and environmental variables. Consequently, the targets may be unsustainable under the spectrum of natural variability inherent in the system or under future climate change. Increasingly, ecologists and restoration planners recognize the value of the long temporal perspective provided by paleoecological data. Advances in paleoclimatology, including better climate proxy methods and temporal resolution, contribute to our understanding of ecosystem response to anthropogenic and climatic forcing at all time scales. We highlight paleoecological research in the Chesapeake Bay and the Florida Everglades and summarize the resulting contributions to restoration planning. Integration of paleoecological, historic, monitoring, and modeling efforts will lead to the development of sustainable, adaptive management strategies for ecosystem restoration.},\n\tnumber = {9},\n\tjournal = {Frontiers in Ecology and the Environment},\n\tauthor = {Willard, D a and Cronin, T M},\n\tyear = {2007},\n\tnote = {Number: 9\nISBN: 1540-9295},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {491--498},\n}\n\n
\n
\n\n\n
\n Climate extremes that cause droughts, floods, or large temperature fluctuations can complicate ecosystem restoration efforts focused on local and regional human disturbance. Restoration targets are often based primarily on monitoring data and modeling simulations, which provide information on species' short-term response to disturbance and environmental variables. Consequently, the targets may be unsustainable under the spectrum of natural variability inherent in the system or under future climate change. Increasingly, ecologists and restoration planners recognize the value of the long temporal perspective provided by paleoecological data. Advances in paleoclimatology, including better climate proxy methods and temporal resolution, contribute to our understanding of ecosystem response to anthropogenic and climatic forcing at all time scales. We highlight paleoecological research in the Chesapeake Bay and the Florida Everglades and summarize the resulting contributions to restoration planning. Integration of paleoecological, historic, monitoring, and modeling efforts will lead to the development of sustainable, adaptive management strategies for ecosystem restoration.\n
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\n \n\n \n \n \n \n \n Effects of watershed and estuarine characteristics on the abundance of submerged aquatic vegetation in Chesapeake bay subestuaries.\n \n \n \n\n\n \n Li, X.; Weller, D. E.; Gallegos, C. L.; Jordan, T. E.; and Kim, H. C.\n\n\n \n\n\n\n Estuaries and Coasts. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{li_effects_2007,\n\ttitle = {Effects of watershed and estuarine characteristics on the abundance of submerged aquatic vegetation in {Chesapeake} bay subestuaries},\n\tdoi = {10.1007/BF02841338},\n\tabstract = {Watershed land use can affect submerged aquatic vegetation (SAV) by elevating nutrient and sediment loading to estuaries. We analyzed the effects of watershed use and estuarine characteristics on the spatial variation of SAV abundance among 101 shallow subestuaries of Chesapeake Bay during 1984-2003. Areas of these subestuaries range from 0.1 to 101 km2, and their associated local watershed areas range from 6 to 1664 km2. Watershed land cover ranges from 6\\% to 81\\% forest, 1\\% to 64\\% cropland, 2\\% to 38\\% grassland, and 0.3\\% to 89\\% developed land. Landscape analyses were applied to develop a number of subestuary metrics (such as subestuary area, mouth width, elongation ratio, fractal dimension of shoreline, and the ratio of local watershed area to subestuary area) and watershed metrics (such as watershed area). Using mapped data from aerial SAV surveys, we calculated SAV coverage for each subestuary in each year during 1984-2003 as a proportion of potential SAV habitat (the area {\\textbackslash}textless 2 m deep). The variation in SAV abundance among subestuaries was strongly linked with subestuary and watershed characteristics. A regression tree model indicated that 60\\% of the variance in SAV abundance could be explained by subestuary fractal dimension, mean tidal range, local watershed dominant land cover, watershed to subestuary area ratio, and mean wave height. Similar explanatory powers were found in wet and dry years, but different independent variables were used. Repeated measures ANOVA with multiple-mean comparison showed that SAV abundance declined with the dominant watershed land cover in the order: forested, mixed-undisturbed, or mixed-developed {\\textbackslash}textgreater mixed-agricultural {\\textbackslash}textgreater agricultural {\\textbackslash}textgreater developed. Change-point analyses indicated strong threshold responses of SAV abundance to point source total nitrogen and phosphorus inputs, the ratio of local watershed area to subestuary area, and septic system density in the local watershed. © 2007 Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Li, Xuyong and Weller, Donald E. and Gallegos, Charles L. and Jordan, Thomas E. and Kim, Hae Cheol},\n\tyear = {2007},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Watershed land use can affect submerged aquatic vegetation (SAV) by elevating nutrient and sediment loading to estuaries. We analyzed the effects of watershed use and estuarine characteristics on the spatial variation of SAV abundance among 101 shallow subestuaries of Chesapeake Bay during 1984-2003. Areas of these subestuaries range from 0.1 to 101 km2, and their associated local watershed areas range from 6 to 1664 km2. Watershed land cover ranges from 6% to 81% forest, 1% to 64% cropland, 2% to 38% grassland, and 0.3% to 89% developed land. Landscape analyses were applied to develop a number of subestuary metrics (such as subestuary area, mouth width, elongation ratio, fractal dimension of shoreline, and the ratio of local watershed area to subestuary area) and watershed metrics (such as watershed area). Using mapped data from aerial SAV surveys, we calculated SAV coverage for each subestuary in each year during 1984-2003 as a proportion of potential SAV habitat (the area \\textless 2 m deep). The variation in SAV abundance among subestuaries was strongly linked with subestuary and watershed characteristics. A regression tree model indicated that 60% of the variance in SAV abundance could be explained by subestuary fractal dimension, mean tidal range, local watershed dominant land cover, watershed to subestuary area ratio, and mean wave height. Similar explanatory powers were found in wet and dry years, but different independent variables were used. Repeated measures ANOVA with multiple-mean comparison showed that SAV abundance declined with the dominant watershed land cover in the order: forested, mixed-undisturbed, or mixed-developed \\textgreater mixed-agricultural \\textgreater agricultural \\textgreater developed. Change-point analyses indicated strong threshold responses of SAV abundance to point source total nitrogen and phosphorus inputs, the ratio of local watershed area to subestuary area, and septic system density in the local watershed. © 2007 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Wind-driven sediment suspension controls light availability in a shallow coastal lagoon.\n \n \n \n\n\n \n Lawson, S. E.; Wiberg, P. L.; McGlathery, K. J.; and Fugatf, D. C.\n\n\n \n\n\n\n Estuaries and Coasts. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{lawson_wind-driven_2007,\n\ttitle = {Wind-driven sediment suspension controls light availability in a shallow coastal lagoon},\n\tdoi = {10.1007/BF02782971},\n\tabstract = {Light availability is critically important for primary productivity in coastal systems, yet current research approaches may not be adequate in shallow coastal lagoons. Light attenuation in these systems is typically dominated by suspended sediment, while light attenuation in deeper estuaries is often dominated by phytoplankton. This difference in controls on light attenuation suggests that physical processes may exert a greater influence on light availability in coastal lagoons than in deeper estuaries. Light availability in Hog Island Bay, a shallow coastal lagoon on the eastern shore of Virginia, was determined for a summer and late fall time period with different wind conditions. We combined field measurements and a process-based modeling approach that predicts sediment suspension and light availability from waves and currents to examine both the variability and drivers of light attenuation. Total suspended solids was the only significant predictor of light attenuation in Hog Island Bay. Waves and currents in Hog Island Bay responded strongly to wind forcing, with bottom stresses from wind driven waves dominant for 60\\% of the modeled area for the late fall period and 24\\% of the modeled area for the summer period. Higher wind speeds in late fall than in summer caused greater sediment suspension (41 and 3 mg l-1 average, respectively) and lower average (spatial and temporal) downwelling light availability (32\\% and 55\\%, respectively). Because of the episodic nature of wind events and the spatially variable nature of sediment suspension, conventional methods of examining light availability, such as fair-weather monitoring or single in situ recorders, do not adequately represent light conditions for benthic plants. © 2007 Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Lawson, S. E. and Wiberg, P. L. and McGlathery, K. J. and Fugatf, D. C.},\n\tyear = {2007},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Light availability is critically important for primary productivity in coastal systems, yet current research approaches may not be adequate in shallow coastal lagoons. Light attenuation in these systems is typically dominated by suspended sediment, while light attenuation in deeper estuaries is often dominated by phytoplankton. This difference in controls on light attenuation suggests that physical processes may exert a greater influence on light availability in coastal lagoons than in deeper estuaries. Light availability in Hog Island Bay, a shallow coastal lagoon on the eastern shore of Virginia, was determined for a summer and late fall time period with different wind conditions. We combined field measurements and a process-based modeling approach that predicts sediment suspension and light availability from waves and currents to examine both the variability and drivers of light attenuation. Total suspended solids was the only significant predictor of light attenuation in Hog Island Bay. Waves and currents in Hog Island Bay responded strongly to wind forcing, with bottom stresses from wind driven waves dominant for 60% of the modeled area for the late fall period and 24% of the modeled area for the summer period. Higher wind speeds in late fall than in summer caused greater sediment suspension (41 and 3 mg l-1 average, respectively) and lower average (spatial and temporal) downwelling light availability (32% and 55%, respectively). Because of the episodic nature of wind events and the spatially variable nature of sediment suspension, conventional methods of examining light availability, such as fair-weather monitoring or single in situ recorders, do not adequately represent light conditions for benthic plants. © 2007 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n The Distribution of Submersed Aquatic Vegetation in the Fresh and Oligohaline Tidal Potomac River, 2004.\n \n \n \n\n\n \n Rybicki, N. B; Yoon, S. N; Schenk, E. R; and Baldizar, J. B\n\n\n \n\n\n\n Technical Report 2007.\n Publication Title: Open-File Report. U.S. Geological Survey\n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@techreport{rybicki_distribution_2007,\n\ttitle = {The {Distribution} of {Submersed} {Aquatic} {Vegetation} in the {Fresh} and {Oligohaline} {Tidal} {Potomac} {River}, 2004},\n\tabstract = {Introduction Submersed aquatic vegetation (SAV) is a critical component of the Potomac River ecosystem. Though SAV provides important habitat for fauna and stabilizes bottom sediment, very dense beds may restrict recreational and commercial navigation. Exotic species of SAV are managed by the Metropolitan Washington Council of Governments Potomac Aquatic Plant Management Program (PAPMP). Selected beds of exotic SAV species that limit navigation are harvested mechanically. The program began in 1986 when approximately 40 acres of plants were harvested from 18 sites (Metropolitan Washington Council of Governments 1987). Monitoring efforts are an effective means of quantifying the distribution and abundance of the exotic species, Hydrilla verticillata (hydrilla) and other SAV species. These annual surveys provide a basis for identifying large-scale changes throughout the ecosystem and allow managers to evaluate the effectiveness of resource management policies based on a reliable scientific foundation. The U.S. Geological Survey (USGS) has monitored the distribution and composition of SAV beds in the fresh and oligohaline (salinity 0.5 to 5) tidal Potomac River since 1978 using transect sampling (1978 to 1981, 1985 to 1987, and 2002) and shoreline surveys (1983 to 2004). Shoreline survey data from the tidal Potomac River are incorporated into the Virginia Institute of Marine Science (VIMS) annual report on SAV distribution in Chesapeake Bay. The VIMS report and methods are available at http://www.vims.edu/bio/sav. Additional publications concerning SAV distribution in the Potomac River can be found at http://water.usgs.gov/nrp/proj.bib/sav/wethome.htm.},\n\tauthor = {Rybicki, Nancy B and Yoon, Sarah N and Schenk, Edward R and Baldizar, Julie B},\n\tyear = {2007},\n\tnote = {Publication Title: Open-File Report. U.S. Geological Survey},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Introduction Submersed aquatic vegetation (SAV) is a critical component of the Potomac River ecosystem. Though SAV provides important habitat for fauna and stabilizes bottom sediment, very dense beds may restrict recreational and commercial navigation. Exotic species of SAV are managed by the Metropolitan Washington Council of Governments Potomac Aquatic Plant Management Program (PAPMP). Selected beds of exotic SAV species that limit navigation are harvested mechanically. The program began in 1986 when approximately 40 acres of plants were harvested from 18 sites (Metropolitan Washington Council of Governments 1987). Monitoring efforts are an effective means of quantifying the distribution and abundance of the exotic species, Hydrilla verticillata (hydrilla) and other SAV species. These annual surveys provide a basis for identifying large-scale changes throughout the ecosystem and allow managers to evaluate the effectiveness of resource management policies based on a reliable scientific foundation. The U.S. Geological Survey (USGS) has monitored the distribution and composition of SAV beds in the fresh and oligohaline (salinity 0.5 to 5) tidal Potomac River since 1978 using transect sampling (1978 to 1981, 1985 to 1987, and 2002) and shoreline surveys (1983 to 2004). Shoreline survey data from the tidal Potomac River are incorporated into the Virginia Institute of Marine Science (VIMS) annual report on SAV distribution in Chesapeake Bay. The VIMS report and methods are available at http://www.vims.edu/bio/sav. Additional publications concerning SAV distribution in the Potomac River can be found at http://water.usgs.gov/nrp/proj.bib/sav/wethome.htm.\n
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\n \n\n \n \n \n \n \n SeagrassNet monitoring across the Americas: Case studies of seagrass decline.\n \n \n \n\n\n \n Short, F. T.; Koch, E. W.; Creed, J. C.; Magalhães, K. M.; Fernandez, E.; and Gaeckle, J. L.\n\n\n \n\n\n\n Marine Ecology. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{short_seagrassnet_2006,\n\ttitle = {{SeagrassNet} monitoring across the {Americas}: {Case} studies of seagrass decline},\n\tdoi = {10.1111/j.1439-0485.2006.00095.x},\n\tabstract = {Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land-sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1-2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action. © 2006 The Authors. Journal compilation 2006 Blackwell Publishing Ltd.},\n\tjournal = {Marine Ecology},\n\tauthor = {Short, Frederick T. and Koch, Evamaria W. and Creed, Joel C. and Magalhães, Karine M. and Fernandez, Eric and Gaeckle, Jeffrey L.},\n\tyear = {2006},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land-sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1-2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action. © 2006 The Authors. Journal compilation 2006 Blackwell Publishing Ltd.\n
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\n \n\n \n \n \n \n \n A Global Crisis for Seagrass Ecosystems.\n \n \n \n\n\n \n ORTH, R. J.; CARRUTHERS, T. J. B.; DENNISON, W. C.; DUARTE, C. M.; FOURQUREAN, J. W.; HECK, K. L.; HUGHES, A. R.; KENDRICK, G. A.; KENWORTHY, W. J.; OLYARNIK, S.; SHORT, F. T.; WAYCOTT, M.; and WILLIAMS, S. L.\n\n\n \n\n\n\n BioScience. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_global_2006,\n\ttitle = {A {Global} {Crisis} for {Seagrass} {Ecosystems}},\n\tdoi = {10.1641/0006-3568(2006)56[987:agcfse]2.0.co;2},\n\tabstract = {Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal human population pressures. Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions. They also serve as “coastal canaries,” global biological sentinels of increasing anthropogenic influences in coastal ecosystems, with large-scale losses reported worldwide. Multiple stressors, including sediment and nutrient runoff, physical disturbance, invasive species, disease, commercial fishing practices, aquaculture, overgrazing, algal blooms, and global warming, cause seagrass declines at scales of square meters to hundreds of square kilometers. Reported seagrass losses have led to increased awareness of the need for seagrass protection, monitoring, management, and restoration. However, seagrass science, which has rapidly grown, is disconnected from public awareness of seagrasses, which has lagged behind awareness of other coastal ecosystems. There is a critical need for a targeted global conservation effort that includes a reduction of watershed nutrient and sediment inputs to seagrass habitats and a targeted educational program informing regulators and the public of the value of seagrass meadows.},\n\tjournal = {BioScience},\n\tauthor = {ORTH, ROBERT J. and CARRUTHERS, TIM J. B. and DENNISON, WILLIAM C. and DUARTE, CARLOS M. and FOURQUREAN, JAMES W. and HECK, KENNETH L. and HUGHES, A. RANDALL and KENDRICK, GARY A. and KENWORTHY, W. JUDSON and OLYARNIK, SUZANNE and SHORT, FREDERICK T. and WAYCOTT, MICHELLE and WILLIAMS, SUSAN L.},\n\tyear = {2006},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal human population pressures. Seagrasses provide key ecological services, including organic carbon production and export, nutrient cycling, sediment stabilization, enhanced biodiversity, and trophic transfers to adjacent habitats in tropical and temperate regions. They also serve as “coastal canaries,” global biological sentinels of increasing anthropogenic influences in coastal ecosystems, with large-scale losses reported worldwide. Multiple stressors, including sediment and nutrient runoff, physical disturbance, invasive species, disease, commercial fishing practices, aquaculture, overgrazing, algal blooms, and global warming, cause seagrass declines at scales of square meters to hundreds of square kilometers. Reported seagrass losses have led to increased awareness of the need for seagrass protection, monitoring, management, and restoration. However, seagrass science, which has rapidly grown, is disconnected from public awareness of seagrasses, which has lagged behind awareness of other coastal ecosystems. There is a critical need for a targeted global conservation effort that includes a reduction of watershed nutrient and sediment inputs to seagrass habitats and a targeted educational program informing regulators and the public of the value of seagrass meadows.\n
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\n \n\n \n \n \n \n \n Seagrass recovery in the Delmarva Coastal Bays, USA.\n \n \n \n\n\n \n Orth, R. J.; Luckenbach, M. L.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Aquatic Botany. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_seagrass_2006,\n\ttitle = {Seagrass recovery in the {Delmarva} {Coastal} {Bays}, {USA}},\n\tdoi = {10.1016/j.aquabot.2005.07.007},\n\tabstract = {Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319 ha reported through 2003 compared to 2129 ha in 1986, an average expansion rate of 305 ha year -1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4 m 2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2 ha in four coastal bays having no seagrass, totaling approximately 46 ha through 2004. Successful germination (estimated at 5-10\\% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38\\% of the bottom in 52-0.4 ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds. © 2005 Elsevier B.V. All rights reserved.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Luckenbach, Mark L. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tyear = {2006},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319 ha reported through 2003 compared to 2129 ha in 1986, an average expansion rate of 305 ha year -1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4 m 2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2 ha in four coastal bays having no seagrass, totaling approximately 46 ha through 2004. Successful germination (estimated at 5-10% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38% of the bottom in 52-0.4 ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds. © 2005 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Eutrophication of Chesapeake Bay: Historical trends and ecological interactions.\n \n \n \n\n\n \n Kemp, W. M.; Boynton, W. R.; Adolf, J. E.; Boesch, D. F.; Boicourt, W. C.; Brush, G.; Cornwell, J. C.; Fisher, T. R.; Glibert, P. M.; Hagy, J. D.; Harding, L. W.; Houde, E. D.; Kimmel, D. G.; Miller, W. D.; Newell, R. I.; Roman, M. R.; Smith, E. M.; and Stevenson, J. C.\n\n\n \n\n\n\n 2005.\n Publication Title: Marine Ecology Progress Series\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{kemp_eutrophication_2005,\n\ttitle = {Eutrophication of {Chesapeake} {Bay}: {Historical} trends and ecological interactions},\n\tabstract = {This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in ∼200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared ∼100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macro-infauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay's overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest fundamental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others. © Inter-Research 2005.},\n\tauthor = {Kemp, W. M. and Boynton, W. R. and Adolf, J. E. and Boesch, D. F. and Boicourt, W. C. and Brush, G. and Cornwell, J. C. and Fisher, T. R. and Glibert, P. M. and Hagy, J. D. and Harding, L. W. and Houde, E. D. and Kimmel, D. G. and Miller, W. D. and Newell, R. I.E. and Roman, M. R. and Smith, E. M. and Stevenson, J. C.},\n\tyear = {2005},\n\tdoi = {10.3354/meps303001},\n\tnote = {Publication Title: Marine Ecology Progress Series},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in ∼200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared ∼100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macro-infauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay's overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest fundamental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others. © Inter-Research 2005.\n
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\n \n\n \n \n \n \n \n Historical Analysis of Submerged Aquatic Vegetation (SAV) in the Potomac River and Analysis of Bay-wide SAV Data to Establish a New Acreage Goal.\n \n \n \n\n\n \n Moore, K.; Wilcox, D.; and Anderson, B.\n\n\n \n\n\n\n . January 2004.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_historical_2004,\n\ttitle = {Historical {Analysis} of {Submerged} {Aquatic} {Vegetation} ({SAV}) in the {Potomac} {River} and {Analysis} of {Bay}-wide {SAV} {Data} to {Establish} a {New} {Acreage} {Goal}},\n\tauthor = {Moore, Kenneth and Wilcox, David and Anderson, Britt},\n\tmonth = jan,\n\tyear = {2004},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Substrate selection by blue crab Callinectes sapidus megalopae and first juvenile instars.\n \n \n \n\n\n \n Van Montfrans, J.; Ryer, C. H.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 260: 209–217. 2003.\n ISBN: 0171-8630\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{van_montfrans_substrate_2003,\n\ttitle = {Substrate selection by blue crab {Callinectes} sapidus megalopae and first juvenile instars},\n\tvolume = {260},\n\tdoi = {10.3354/meps260209},\n\tabstract = {Various marine and estuarine species utilize chemical cues during settlement. We investigated responses by megalopae and first juvenile (J1) blue crabs to common Chesapeake Bay substrates in mesocosm and field experiments. Mesocosm trials examined responses of megalopae or J1 crabs to sand, marsh mud, live oysters Crassostrea virginica, sun-bleached oyster shell, eel grass Zostera marina and artificial seagrass in replicate 160 l tanks. Either 10 megalopae or J1 crabs isolated in each of 6 substrates were allowed total access after acclimation to test the null hypothesis of equal distribution among substrates after 13 h. Thirty-five percent of megalopae were recovered from Z. marina, with the remaining substrates containing fewer than half that many. In contrast, 30 \\% of J1 crabs (with only 17 \\% recovered from Z. marina) were found in live C. virginica. A field experiment quantified responses of ingressing megalopae to Z, marina, marsh mud, and C. virginica. Overnight settlement was significantly higher in Z. marina ((x) over bar = 3.3 ind.; 60 \\% of total) when compared to mud ((x) over bar = 0.9; 16 \\%) or C. virginica ((x) over bar = 1.3; 24 \\%). Likewise, J1 crabs were significantly more numerous in Z. marina ((x) over bar = 3.7 ind.; 55 \\% of total) than in C. virginica ((x) over bar = 1.8; 27 \\%) and mud ((x) over bar = 1.2; 18 \\%). J1 crab distribution in field plots likely reflected habitat selection by megalopae; laboratory results were equivocal and probably due to artifacts associated with density-dependent agonism. The initial non-random distribution of blue crabs in Chesapeake Bay may be deterministic and due to habitat-selection behavior by megalopae. Selection for seagrass assures the greatest likelihood of maximal survival and accelerated growth. Similar relationships may also exist in estuarine-dependent species with comparable habitat requirements and life-history characteristics},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Van Montfrans, Jacques and Ryer, Clifford H. and Orth, Robert J.},\n\tyear = {2003},\n\tnote = {ISBN: 0171-8630},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {209--217},\n}\n\n
\n
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\n Various marine and estuarine species utilize chemical cues during settlement. We investigated responses by megalopae and first juvenile (J1) blue crabs to common Chesapeake Bay substrates in mesocosm and field experiments. Mesocosm trials examined responses of megalopae or J1 crabs to sand, marsh mud, live oysters Crassostrea virginica, sun-bleached oyster shell, eel grass Zostera marina and artificial seagrass in replicate 160 l tanks. Either 10 megalopae or J1 crabs isolated in each of 6 substrates were allowed total access after acclimation to test the null hypothesis of equal distribution among substrates after 13 h. Thirty-five percent of megalopae were recovered from Z. marina, with the remaining substrates containing fewer than half that many. In contrast, 30 % of J1 crabs (with only 17 % recovered from Z. marina) were found in live C. virginica. A field experiment quantified responses of ingressing megalopae to Z, marina, marsh mud, and C. virginica. Overnight settlement was significantly higher in Z. marina ((x) over bar = 3.3 ind.; 60 % of total) when compared to mud ((x) over bar = 0.9; 16 %) or C. virginica ((x) over bar = 1.3; 24 %). Likewise, J1 crabs were significantly more numerous in Z. marina ((x) over bar = 3.7 ind.; 55 % of total) than in C. virginica ((x) over bar = 1.8; 27 %) and mud ((x) over bar = 1.2; 18 %). J1 crab distribution in field plots likely reflected habitat selection by megalopae; laboratory results were equivocal and probably due to artifacts associated with density-dependent agonism. The initial non-random distribution of blue crabs in Chesapeake Bay may be deterministic and due to habitat-selection behavior by megalopae. Selection for seagrass assures the greatest likelihood of maximal survival and accelerated growth. Similar relationships may also exist in estuarine-dependent species with comparable habitat requirements and life-history characteristics\n
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\n \n\n \n \n \n \n \n Submerged aquatic vegetation in the mesohaline region of the Patuxent estuary: Past, present, and future status.\n \n \n \n\n\n \n Stankelis, R. M.; Naylor, M. D.; and Boynton, W. R.\n\n\n \n\n\n\n Estuaries. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{stankelis_submerged_2003,\n\ttitle = {Submerged aquatic vegetation in the mesohaline region of the {Patuxent} estuary: {Past}, present, and future status},\n\tdoi = {10.1007/BF02695961},\n\tabstract = {The loss of submerged aquatic vegetation (SAV) from the Patuxent estuary during the latter part of the 20th century was explored using diverse data sets that included historic SAV coverage and distribution data, SAV ground truth observations, water clarity and nutrient loading data, and epiphyte light attenuation measurements. Analysis of aerial photography from 1952 showed that SAV was abundant and widely distributed along the entire mesohaline region of the estuary; by the late 1960s rapid declines in SAV took place following large increases in nutrient loading to the estuary. An examination of water clarity and epiphyte data suggest that the processes that led to the loss of SAV varied in strength along the axis of the estuary. In the upper mesohaline region, Secchi depths were consistently less than established mesohaline SAV habitat requirements at 1-m water depth, suggesting that water clarity was responsible for SAV decline. In the lower mesohaline region, where water clarity was consistently above SAV requirements, high epiphyte fouling rates significantly reduced light available to SAV. Experimental results show that epiphyte fouling had the capacity to reduce available light to SAV blades from 30\\% to 7\\% of surface light within a week, and likely contributed to the local decline and near total loss of SAV during the late 1960s and early 1970s. The prognosis for near-term SAV recovery within the mesohaline portion of the estuary seems unlikely given existing water quality conditions.},\n\tjournal = {Estuaries},\n\tauthor = {Stankelis, Robert M. and Naylor, Michael D. and Boynton, Walter R.},\n\tyear = {2003},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n The loss of submerged aquatic vegetation (SAV) from the Patuxent estuary during the latter part of the 20th century was explored using diverse data sets that included historic SAV coverage and distribution data, SAV ground truth observations, water clarity and nutrient loading data, and epiphyte light attenuation measurements. Analysis of aerial photography from 1952 showed that SAV was abundant and widely distributed along the entire mesohaline region of the estuary; by the late 1960s rapid declines in SAV took place following large increases in nutrient loading to the estuary. An examination of water clarity and epiphyte data suggest that the processes that led to the loss of SAV varied in strength along the axis of the estuary. In the upper mesohaline region, Secchi depths were consistently less than established mesohaline SAV habitat requirements at 1-m water depth, suggesting that water clarity was responsible for SAV decline. In the lower mesohaline region, where water clarity was consistently above SAV requirements, high epiphyte fouling rates significantly reduced light available to SAV. Experimental results show that epiphyte fouling had the capacity to reduce available light to SAV blades from 30% to 7% of surface light within a week, and likely contributed to the local decline and near total loss of SAV during the late 1960s and early 1970s. The prognosis for near-term SAV recovery within the mesohaline portion of the estuary seems unlikely given existing water quality conditions.\n
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\n \n\n \n \n \n \n \n \n Analysis of Histocial Distribution of SAV in the Eastern Shore Coastal Basins and Mid-Bay Island Complexes as Evidence of Historical Water Quality Conditions and a Restored Bay Ecosystem.\n \n \n \n \n\n\n \n Moore, K.; Wilcox, D.; Anderson, B.; and Orth, R.\n\n\n \n\n\n\n Reports. April 2003.\n \n\n\n\n
\n\n\n\n \n \n \"AnalysisPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{moore_analysis_2003,\n\ttitle = {Analysis of {Histocial} {Distribution} of {SAV} in the {Eastern} {Shore} {Coastal} {Basins} and {Mid}-{Bay} {Island} {Complexes} as {Evidence} of {Historical} {Water} {Quality} {Conditions} and a {Restored} {Bay} {Ecosystem}},\n\turl = {https://scholarworks.wm.edu/reports/1055},\n\tdoi = {https://doi.org/10.21220/V5TF1P},\n\tjournal = {Reports},\n\tauthor = {Moore, Kenneth and Wilcox, David and Anderson, Britt and Orth, R.},\n\tmonth = apr,\n\tyear = {2003},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Seagrasses of the Mid-Atlantic coast of the USA.\n \n \n \n\n\n \n Koch, E.; and Orth, R.\n\n\n \n\n\n\n In pages 216–223. January 2003.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@incollection{koch_seagrasses_2003,\n\ttitle = {Seagrasses of the {Mid}-{Atlantic} coast of the {USA}},\n\tauthor = {Koch, Evamaria and Orth, Robert},\n\tmonth = jan,\n\tyear = {2003},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {216--223},\n}\n\n
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\n \n\n \n \n \n \n \n \n Identification and Management of Fishing Gear Impacts in a Recovering Seagrass System in the Coastal Bays of the Delmarva Peninsula, USA.\n \n \n \n \n\n\n \n Orth, R. J.; Fishman, J. R.; Wilcox, D. J.; and Moore, K. A.\n\n\n \n\n\n\n Journal of Coastal Research,111–129. 2002.\n Publisher: Coastal Education & Research Foundation, Inc.\n\n\n\n
\n\n\n\n \n \n \"IdentificationPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_identification_2002,\n\ttitle = {Identification and {Management} of {Fishing} {Gear} {Impacts} in a {Recovering} {Seagrass} {System} in the {Coastal} {Bays} of the {Delmarva} {Peninsula}, {USA}},\n\tissn = {0749-0208},\n\turl = {https://www.jstor.org/stable/25736347},\n\tabstract = {Seagrass beds in the coastal bays of the Delmarva Peninsula have been recovering steadily over the past several decades after a major decline in the 1930s. However, in 1997 severe damage to the grass beds was noted and attributed to two types of hard clam fishing gear: hydraulic dredges and modified oyster dredges. We analyzed aerial photography and conducted ground transect studies to quantify the damage caused by these gears to the dominant seagrass in the region, Zostera marina, and evaluate the recovery in the scars over a 4–5 year period. Seagrass area affected by hydraulic dredging increased from 53 ha to 508 ha between 1996 and 1997, while modified oyster dredge scars increased from 10 to 218 scars between 1995 and 1997. Analysis of the recovery from both types of scarring showed that some scars require more than three years to revegetate to undisturbed levels. Once notified of these impacts, legislators in Maryland and resource managers in Maryland and Virginia responded within several months to protect seagrass through law and regulation preventing clam dredging within grass beds. In Virginia, the new regulation was successful in reducing scarring, but required later revisions for successful enforcement. In Maryland, however, procedural requirements to fully implement the law required additional time, during which scarring increased to 1,257 total ha in 1999. Maryland's law was changed in 2002 to enhance protection of the state's seagrass beds. This issue has demonstrated the importance of close linkages between the scientific research community, politicians, management agencies, law enforcement, and the public, as well as the importance of sanctuaries or protection zones to prevent damage to critical seagrass habitats.},\n\turldate = {2020-05-15},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Orth, Robert J. and Fishman, James R. and Wilcox, David J. and Moore, Kenneth A.},\n\tyear = {2002},\n\tnote = {Publisher: Coastal Education \\& Research Foundation, Inc.},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {111--129},\n}\n\n
\n
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\n Seagrass beds in the coastal bays of the Delmarva Peninsula have been recovering steadily over the past several decades after a major decline in the 1930s. However, in 1997 severe damage to the grass beds was noted and attributed to two types of hard clam fishing gear: hydraulic dredges and modified oyster dredges. We analyzed aerial photography and conducted ground transect studies to quantify the damage caused by these gears to the dominant seagrass in the region, Zostera marina, and evaluate the recovery in the scars over a 4–5 year period. Seagrass area affected by hydraulic dredging increased from 53 ha to 508 ha between 1996 and 1997, while modified oyster dredge scars increased from 10 to 218 scars between 1995 and 1997. Analysis of the recovery from both types of scarring showed that some scars require more than three years to revegetate to undisturbed levels. Once notified of these impacts, legislators in Maryland and resource managers in Maryland and Virginia responded within several months to protect seagrass through law and regulation preventing clam dredging within grass beds. In Virginia, the new regulation was successful in reducing scarring, but required later revisions for successful enforcement. In Maryland, however, procedural requirements to fully implement the law required additional time, during which scarring increased to 1,257 total ha in 1999. Maryland's law was changed in 2002 to enhance protection of the state's seagrass beds. This issue has demonstrated the importance of close linkages between the scientific research community, politicians, management agencies, law enforcement, and the public, as well as the importance of sanctuaries or protection zones to prevent damage to critical seagrass habitats.\n
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\n \n\n \n \n \n \n \n \n Analysis of Historical Distribution of Submerged Aquatic Vegetation (SAV) in the York and Rappahannock Rivers as Evidence of Historical Water Quality Conditions.\n \n \n \n \n\n\n \n Moore, K.; Wilcox, D.; Anderson, B.; and Orth, R.\n\n\n \n\n\n\n Reports. December 2001.\n \n\n\n\n
\n\n\n\n \n \n \"AnalysisPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_analysis_2001,\n\ttitle = {Analysis of {Historical} {Distribution} of {Submerged} {Aquatic} {Vegetation} ({SAV}) in the {York} and {Rappahannock} {Rivers} as {Evidence} of {Historical} {Water} {Quality} {Conditions}},\n\turl = {https://scholarworks.wm.edu/reports/1054},\n\tdoi = {https://doi.org/10.21220/V5Z740},\n\tjournal = {Reports},\n\tauthor = {Moore, Ken and Wilcox, David and Anderson, Britt and Orth, R.},\n\tmonth = dec,\n\tyear = {2001},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Paleoecology of submerged macrophytes in the upper Chesapeake Bay.\n \n \n \n\n\n \n Brush, G. S.; and Hilgartner, W. B.\n\n\n \n\n\n\n Ecological Monographs. 2000.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{brush_paleoecology_2000,\n\ttitle = {Paleoecology of submerged macrophytes in the upper {Chesapeake} {Bay}},\n\tdoi = {10.1890/0012-9615(2000)070[0645:POSMIT]2.0.CO;2},\n\tabstract = {Fossil seed distributions of submerged aquatic vegetation (SAV) from dated sediment cores in tributaries of the upper Chesapeake Bay show prehistoric changes in species composition and abundance and reflect the response of SAV species to human disturbance since European settlement. The interval of time spanned by the cores includes several centuries prior to, and three centuries following, European settlement. Species diversity is greatest in the low-salinity northern and upper tributaries, while areas of higher salinity and extensive salt marshes are characterized by low diversity or absence of SAV. Mapped distributions of seed abundances show the migration from upstream to downstream in some tributaries of the brackish species Potamogeton perfoliatus, Zannichellia palustris, and Ruppia maritima following deforestation. The largest increase in SAV, represented by the highest abundance of fossilized seeds, occurred during the 1700s after Europeans first cleared the land for farms, and the largest and most widespread decline took place in the 1960S and 1970s after most of the watershed had been at one time or another cleared and heavily fertilized for agriculture. Distributions of SAV are highly variable both temporally and spatially, reflecting the dynamic nature of estuarine habitats. Despite high environmental variability, local and regional extinctions occurred only in the most recent decades, indicating a threshold response to land use changes and nutrient loading which had begun at least two centuries earlier and intensified in the mid- to late 19th century.},\n\tjournal = {Ecological Monographs},\n\tauthor = {Brush, G. S. and Hilgartner, W. B.},\n\tyear = {2000},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Fossil seed distributions of submerged aquatic vegetation (SAV) from dated sediment cores in tributaries of the upper Chesapeake Bay show prehistoric changes in species composition and abundance and reflect the response of SAV species to human disturbance since European settlement. The interval of time spanned by the cores includes several centuries prior to, and three centuries following, European settlement. Species diversity is greatest in the low-salinity northern and upper tributaries, while areas of higher salinity and extensive salt marshes are characterized by low diversity or absence of SAV. Mapped distributions of seed abundances show the migration from upstream to downstream in some tributaries of the brackish species Potamogeton perfoliatus, Zannichellia palustris, and Ruppia maritima following deforestation. The largest increase in SAV, represented by the highest abundance of fossilized seeds, occurred during the 1700s after Europeans first cleared the land for farms, and the largest and most widespread decline took place in the 1960S and 1970s after most of the watershed had been at one time or another cleared and heavily fertilized for agriculture. Distributions of SAV are highly variable both temporally and spatially, reflecting the dynamic nature of estuarine habitats. Despite high environmental variability, local and regional extinctions occurred only in the most recent decades, indicating a threshold response to land use changes and nutrient loading which had begun at least two centuries earlier and intensified in the mid- to late 19th century.\n
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\n \n\n \n \n \n \n \n Modeling dynamic polygon objects in space and time: A new graph-based technique.\n \n \n \n\n\n \n Wilcox, D. J.; Harwell, M. C.; and Orth, R. J.\n\n\n \n\n\n\n Cartography and Geographic Information Science. 2000.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{wilcox_modeling_2000,\n\ttitle = {Modeling dynamic polygon objects in space and time: {A} new graph-based technique},\n\tdoi = {10.1559/152304000783547894},\n\tabstract = {The analysis of dynamic spatial systems requires an explicit spatio-temporal data model and spatio-temporal analysis tools. Event-based models have been developed to analyze discrete change in continuous and feature-based spatial data. In this paper, a spatio-temporal graph model is described that supports the analysis of continuous change in feature-based polygon spatial data. The spatio-temporal graph edges, called temporal links, track changes in polygon topology through space and time. The model also introduces the concept of a spatial-interaction region that extends a model's focus beyond short-term local events to encompass long-term regional events. The structure of the spatio-temporal graph is used to classify these events into five types of local polygon events and two types of spatial-interaction region events. To illustrate its utility, the model is applied to the ecological question of how patch size influences longevity in underwater plant communities in Chesapeake Bay, USA. Both a short-term local analysis and a longer-term regional analysis showed that patches of plants, or groups of patches, larger than one to two hectares in size were more likely to persist than smaller patches or groups of patches. Overall, the spatio-temporal graph model approach appears applicable to a variety of spatio-temporal questions.},\n\tjournal = {Cartography and Geographic Information Science},\n\tauthor = {Wilcox, D. J. and Harwell, M. C. and Orth, R. J.},\n\tyear = {2000},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n The analysis of dynamic spatial systems requires an explicit spatio-temporal data model and spatio-temporal analysis tools. Event-based models have been developed to analyze discrete change in continuous and feature-based spatial data. In this paper, a spatio-temporal graph model is described that supports the analysis of continuous change in feature-based polygon spatial data. The spatio-temporal graph edges, called temporal links, track changes in polygon topology through space and time. The model also introduces the concept of a spatial-interaction region that extends a model's focus beyond short-term local events to encompass long-term regional events. The structure of the spatio-temporal graph is used to classify these events into five types of local polygon events and two types of spatial-interaction region events. To illustrate its utility, the model is applied to the ecological question of how patch size influences longevity in underwater plant communities in Chesapeake Bay, USA. Both a short-term local analysis and a longer-term regional analysis showed that patches of plants, or groups of patches, larger than one to two hectares in size were more likely to persist than smaller patches or groups of patches. Overall, the spatio-temporal graph model approach appears applicable to a variety of spatio-temporal questions.\n
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\n \n\n \n \n \n \n \n Analysis of the abundance of submersed aquatic vegetation communities in the Chesapeake Bay.\n \n \n \n\n\n \n Moore, K. A.; Wilcox, D. J.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 2000.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_analysis_2000,\n\ttitle = {Analysis of the abundance of submersed aquatic vegetation communities in the {Chesapeake} {Bay}},\n\tdoi = {10.2307/1353229},\n\tabstract = {A procedure was developed using aboveground field biomass measurements of Chesapeake Bay submersed aquatic vegetation (SAV), yearly species identification surveys, annual photographic mapping at 1:24,000 scale, and geographic information system (GIS) analyses to determine the SAV community type, biomass, and area of each mapped SAV bed in the bay and its tidal tributaries for the period of 1985 through 1996. Using species identifications provided through over 10,000 SAV ground survey observations, the 17 most abundant SAV species found in the bay were clustered into four species associations: ZOSTERA, RUPPIA, POTAMOGETON, and FRESHWATER MIXED. Monthly aboveground biomass values were then assigned to each bed or bed section based upon monthly biomass models developed for each community. High salinity communities (ZOSTERA) were found to dominate total bay SAV aboveground biomass during winter, spring, and summer. Lower salinity communities (RUPPIA, POTAMOGETON, and FRESHWATER MIXED) dominated in the fall. In 1996, total bay SAV standing stock was nearly 22,800 metric tons at annual maximum biomass in July encompassing an area of approximately 25,670 hectares. Minimum biomass in December and January of that year was less than 5,000 metric tons. SAV annual maximum biomass increased baywide from lows of less than 15,000 metric tons in 1985 and 1986 to nearly 25,000 metric tons during the 1991 to 1993 period, while area increased from approximately 20,000 to nearly 30,000 hectares during that same period. Year-to-year comparisons of maximum annual community abundance from 1985 to 1996 indicated that regrowth of SAV in the Chesapeake Bay from 1985-1993 occurred principally in the ZOSTERA community, with 85\\% of the baywide increase in biomass and 71\\% of the increase in area occurring in that community. Maximum biomass of FRESHWATER MIXED SAV beds also increased from a low of 3,200 metric tons in 1985 to a high of 6,650 metric tons in 1993, while maximum biomass of both RUPPIA and POTAMOGETON beds fluctuated between 2,450 and 4,600 metric tons and 60 and 600 metric tons, respectively, during that same period with net declines of 7\\% and 43\\%, respectively, between 1985 and 1996. During the July period of annual, baywide, maximum SAV biomass, SAV beds in the Chesapeake Bay typically averaged approximately 0.86 metric tons of aboveground dry mass per hectare of bed area.},\n\tjournal = {Estuaries},\n\tauthor = {Moore, Kenneth A. and Wilcox, David J. and Orth, Robert J.},\n\tyear = {2000},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n A procedure was developed using aboveground field biomass measurements of Chesapeake Bay submersed aquatic vegetation (SAV), yearly species identification surveys, annual photographic mapping at 1:24,000 scale, and geographic information system (GIS) analyses to determine the SAV community type, biomass, and area of each mapped SAV bed in the bay and its tidal tributaries for the period of 1985 through 1996. Using species identifications provided through over 10,000 SAV ground survey observations, the 17 most abundant SAV species found in the bay were clustered into four species associations: ZOSTERA, RUPPIA, POTAMOGETON, and FRESHWATER MIXED. Monthly aboveground biomass values were then assigned to each bed or bed section based upon monthly biomass models developed for each community. High salinity communities (ZOSTERA) were found to dominate total bay SAV aboveground biomass during winter, spring, and summer. Lower salinity communities (RUPPIA, POTAMOGETON, and FRESHWATER MIXED) dominated in the fall. In 1996, total bay SAV standing stock was nearly 22,800 metric tons at annual maximum biomass in July encompassing an area of approximately 25,670 hectares. Minimum biomass in December and January of that year was less than 5,000 metric tons. SAV annual maximum biomass increased baywide from lows of less than 15,000 metric tons in 1985 and 1986 to nearly 25,000 metric tons during the 1991 to 1993 period, while area increased from approximately 20,000 to nearly 30,000 hectares during that same period. Year-to-year comparisons of maximum annual community abundance from 1985 to 1996 indicated that regrowth of SAV in the Chesapeake Bay from 1985-1993 occurred principally in the ZOSTERA community, with 85% of the baywide increase in biomass and 71% of the increase in area occurring in that community. Maximum biomass of FRESHWATER MIXED SAV beds also increased from a low of 3,200 metric tons in 1985 to a high of 6,650 metric tons in 1993, while maximum biomass of both RUPPIA and POTAMOGETON beds fluctuated between 2,450 and 4,600 metric tons and 60 and 600 metric tons, respectively, during that same period with net declines of 7% and 43%, respectively, between 1985 and 1996. During the July period of annual, baywide, maximum SAV biomass, SAV beds in the Chesapeake Bay typically averaged approximately 0.86 metric tons of aboveground dry mass per hectare of bed area.\n
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\n \n\n \n \n \n \n \n Sediment-based reconstruction of submersed aquatic vegetation distribution in the Severn River, a sub-estuary of Chesapeake Bay.\n \n \n \n\n\n \n Arnold, R. R.; Cornwell, J. C.; Dennison, W. C.; and Stevenson, J. C.\n\n\n \n\n\n\n Journal of Coastal Research. 2000.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{arnold_sediment-based_2000,\n\ttitle = {Sediment-based reconstruction of submersed aquatic vegetation distribution in the {Severn} {River}, a sub-estuary of {Chesapeake} {Bay}},\n\tabstract = {A paleo-ecological reconstruction of long-term changes in the distribution of submersed aquatic vegetation (SAV) in a Chesapeake sub-estuary was made using dated sediment cores on transects going from shallow ({\\textbackslash}textless 0.5 m) to deep ({\\textbackslash}textgreater 2 m) waters. Maynedier and Saltworks Creeks, branches of the Severn River, have had substantial losses of SAV, similar to many parts of the upper Chesapeake Bay. Dating via 210Pb established that sediment accretion rates were 0.5-0.7 cm yr-1 in these two systems, double the rate of sea level rise in this region. Seeds of only two SAV species were found in the sediments despite evidence others were present at one time or another in other tributaries of the Severn Estuary. Of the two species found, Zannichellia palustris seeds were much more abundant than Ruppia mar- itima seeds, reflecting the high dispersibility of the former species. The vertical pattern of seed distribution in these cores indicates that over the past 100 years, SAV (particularly Z. palustris) has been increasingly confined to shallower water depths. Although there is less riverine pulsing in the two study creeks, than at the head of the Bay (where previous seed records are available), both data sets are consistent with the hypothesis that decreasing light availability due to eutrophication and sediment erosion has been a problem for SAV in Chesapeake Bay, particularly over the last several decades. Furthermore this study suggests that historically low species diversity may be attributable to more chronic and longer term stress in the shallows of the Severn River than present in SAV beds at the head of the Bay.},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Arnold, Richard R. and Cornwell, Jeffrey C. and Dennison, William C. and Stevenson, J. Court},\n\tyear = {2000},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n A paleo-ecological reconstruction of long-term changes in the distribution of submersed aquatic vegetation (SAV) in a Chesapeake sub-estuary was made using dated sediment cores on transects going from shallow (\\textless 0.5 m) to deep (\\textgreater 2 m) waters. Maynedier and Saltworks Creeks, branches of the Severn River, have had substantial losses of SAV, similar to many parts of the upper Chesapeake Bay. Dating via 210Pb established that sediment accretion rates were 0.5-0.7 cm yr-1 in these two systems, double the rate of sea level rise in this region. Seeds of only two SAV species were found in the sediments despite evidence others were present at one time or another in other tributaries of the Severn Estuary. Of the two species found, Zannichellia palustris seeds were much more abundant than Ruppia mar- itima seeds, reflecting the high dispersibility of the former species. The vertical pattern of seed distribution in these cores indicates that over the past 100 years, SAV (particularly Z. palustris) has been increasingly confined to shallower water depths. Although there is less riverine pulsing in the two study creeks, than at the head of the Bay (where previous seed records are available), both data sets are consistent with the hypothesis that decreasing light availability due to eutrophication and sediment erosion has been a problem for SAV in Chesapeake Bay, particularly over the last several decades. Furthermore this study suggests that historically low species diversity may be attributable to more chronic and longer term stress in the shallows of the Severn River than present in SAV beds at the head of the Bay.\n
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\n \n\n \n \n \n \n \n \n Analysis of Historical Distribution of Submerged Aquatic Vegetation (SAV) in the James River.\n \n \n \n \n\n\n \n Moore, K.; Wilcox, D.; Orth, R.; and Bailey, E.\n\n\n \n\n\n\n Reports. April 1999.\n \n\n\n\n
\n\n\n\n \n \n \"AnalysisPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_analysis_1999,\n\ttitle = {Analysis of {Historical} {Distribution} of {Submerged} {Aquatic} {Vegetation} ({SAV}) in the {James} {River}},\n\turl = {https://scholarworks.wm.edu/reports/1050},\n\tdoi = {https://doi.org/10.21220/V5G46C},\n\tjournal = {Reports},\n\tauthor = {Moore, Ken and Wilcox, David and Orth, R. and Bailey, Eva},\n\tmonth = apr,\n\tyear = {1999},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Production of reproductive shoots, vegetative shoots, and seeds in populations of Ruppia maritima L. from the Chesapeake Bay, Virginia.\n \n \n \n\n\n \n Silberhorn, G. M.; Dewing, S.; and Mason, P. A.\n\n\n \n\n\n\n Wetlands. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{silberhorn_production_1996,\n\ttitle = {Production of reproductive shoots, vegetative shoots, and seeds in populations of {Ruppia} maritima {L}. from the {Chesapeake} {Bay}, {Virginia}},\n\tdoi = {10.1007/BF03160696},\n\tabstract = {The production of reproductive shoots, vegetative shoots, and seeds was characterized for Ruppia maritima populations in the Virginia portion of Chesapeake Bay in 1988 and 1989. The study locations included two previously unvegetated sites recently colonized by R. maritima in the Rappahannock River and an established site and an irregularly flooded marsh panne site, both in the York River. A corer was used to collect plant material, which was then separated into reproductive shoots, vegetative shoots, and seeds. Sampling took place at approximately 2-week intervals from the time of first observation of flowering shoots until reproductive senescence. Reproductive shoot and seed production were high for all sites, particularly the previously unvegetated sites. The percent of reproductive shoots ranged from less than one percent to 52 percent. One previously unvegetated site produced 23,390 seeds m-2 in 1988, the highest level of seed production measured during this study. Dramatic decreases in production from 1988 to 1989 at two of the study locations, the salt panne and one previously unvegetated site, are attributable to the effects of drought and cownose ray (Rhinoptera bonasus) activity, respectively. High levels of seed production, frequently above 20,000 seeds m-2, and their eventual dispersal may account for the rapid colonization in certain areas of Chesapeake Bay by R. maritima.},\n\tjournal = {Wetlands},\n\tauthor = {Silberhorn, Gene M. and Dewing, Sharon and Mason, Pamela A.},\n\tyear = {1996},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n The production of reproductive shoots, vegetative shoots, and seeds was characterized for Ruppia maritima populations in the Virginia portion of Chesapeake Bay in 1988 and 1989. The study locations included two previously unvegetated sites recently colonized by R. maritima in the Rappahannock River and an established site and an irregularly flooded marsh panne site, both in the York River. A corer was used to collect plant material, which was then separated into reproductive shoots, vegetative shoots, and seeds. Sampling took place at approximately 2-week intervals from the time of first observation of flowering shoots until reproductive senescence. Reproductive shoot and seed production were high for all sites, particularly the previously unvegetated sites. The percent of reproductive shoots ranged from less than one percent to 52 percent. One previously unvegetated site produced 23,390 seeds m-2 in 1988, the highest level of seed production measured during this study. Dramatic decreases in production from 1988 to 1989 at two of the study locations, the salt panne and one previously unvegetated site, are attributable to the effects of drought and cownose ray (Rhinoptera bonasus) activity, respectively. High levels of seed production, frequently above 20,000 seeds m-2, and their eventual dispersal may account for the rapid colonization in certain areas of Chesapeake Bay by R. maritima.\n
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\n \n\n \n \n \n \n \n NOAA Coastal change analysis program (C-CAP): Guidance for regional implementation.\n \n \n \n\n\n \n Dobson, J.; Bright, E.; Ferguson, R.; Field, D.; Wood, L.; Haddad, K.; III, H.; Jensen, J.; Klemas, V.; Orth, R.; and Thomas, J.\n\n\n \n\n\n\n January 1995.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{dobson_noaa_1995,\n\ttitle = {{NOAA} {Coastal} change analysis program ({C}-{CAP}): {Guidance} for regional implementation},\n\tshorttitle = {{NOAA} {Coastal} change analysis program ({C}-{CAP})},\n\tauthor = {Dobson, Jerome and Bright, E. and Ferguson, R. and Field, Don and Wood, L. and Haddad, K. and III, H. and Jensen, J. and Klemas, Victor and Orth, Robert and Thomas, J.},\n\tmonth = jan,\n\tyear = {1995},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Invasions and declines of submersed macrophytes in the tidal potomac river and estuary, the currituck sound-back bay system, and the pamlico river estuary.\n \n \n \n\n\n \n Carter, V.; and Rybicki, N. B.\n\n\n \n\n\n\n Lake and Reservoir Management. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carter_invasions_1994,\n\ttitle = {Invasions and declines of submersed macrophytes in the tidal potomac river and estuary, the currituck sound-back bay system, and the pamlico river estuary},\n\tdoi = {10.1080/07438149409354171},\n\tabstract = {Long-term changes in biomass, species composition, and distribution of submersed aquatic macrophytes have been documented and studied at two sites in the mid-Atlantic region: The tidal Potomac River and Estuary in Maryland, Virginia, and the District of Columbia, and the Currituck Sound-Back Bay system in Virginia and North Carolina. Additional information based on a shorter time period is available for the Pamlico River Estuary in North Carolina. This paper briefly describes the study areas and summaries the history of declines and increases in each area and factors implicated in these changes. The remainder of the paper is devoted to a discussion of factors influencing invasion/establishment success and the current status of submersed macrophytes in the three areas. © 1994 Taylor and Francis Group, LLC.},\n\tjournal = {Lake and Reservoir Management},\n\tauthor = {Carter, Virginia and Rybicki, N. B.},\n\tyear = {1994},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Long-term changes in biomass, species composition, and distribution of submersed aquatic macrophytes have been documented and studied at two sites in the mid-Atlantic region: The tidal Potomac River and Estuary in Maryland, Virginia, and the District of Columbia, and the Currituck Sound-Back Bay system in Virginia and North Carolina. Additional information based on a shorter time period is available for the Pamlico River Estuary in North Carolina. This paper briefly describes the study areas and summaries the history of declines and increases in each area and factors implicated in these changes. The remainder of the paper is devoted to a discussion of factors influencing invasion/establishment success and the current status of submersed macrophytes in the three areas. © 1994 Taylor and Francis Group, LLC.\n
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\n \n\n \n \n \n \n \n Role of weather and water quality in population dynamics of submersed macrophytes in the tidal Potomac River.\n \n \n \n\n\n \n Carter, V.; Rybicki, N. B.; Landwehr, J. M.; and Turtora, M.\n\n\n \n\n\n\n Estuaries. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carter_role_1994,\n\ttitle = {Role of weather and water quality in population dynamics of submersed macrophytes in the tidal {Potomac} {River}},\n\tdoi = {10.2307/1352674},\n\tabstract = {Weather and water-quality data from 1980 to 1989 were correlated with fluctuations in submersed macrophyte populations in the tidal Potomac River near Washington, D.C., to elucidate causal relationships and explain population dynamics. Both reaches were unvegetated in 1980 when mean growing-season Secchi depths were {\\textbackslash}textless0.60 m. Macrophyte resurgence in the upper tidal river in 1983 was associated with a growing-season Secchi depth of 0.86 m, total suspended solids (TSS) of 17.7 mg l−1, chlorophyll a concentrations of 15.2 μg l−1, significantly higher than average percent available sunshine, and significantly lower than average wind speed. From 1983 to 1989, mean seasonal Secchi depths {\\textbackslash}textless0.65 m were associated with decrease in plant coverage and mean seasonal Secchi depths {\\textbackslash}textgreater0.65 were associated with increases in plant coverage. Changes in mean seasonal Secchi depth were related to changes in mean seasonal TSS and chlorophyll a concentration; mean Secchi depths {\\textbackslash}textgreater0.65 generally occur when seasonal mean TSS is {\\textbackslash}textless19 mg l−1 and seasonal mean chlorophyll a concentration is ≤15 μg l−1. Secchi depth is highly correlated with plant growth in the upper tidal river and chlorophyll a and TSS with plant growth in the lower tidal river. Wind speed is an important influence on plant growth in both reaches. © 1994, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B. and Landwehr, Jurate M. and Turtora, Michael},\n\tyear = {1994},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Weather and water-quality data from 1980 to 1989 were correlated with fluctuations in submersed macrophyte populations in the tidal Potomac River near Washington, D.C., to elucidate causal relationships and explain population dynamics. Both reaches were unvegetated in 1980 when mean growing-season Secchi depths were \\textless0.60 m. Macrophyte resurgence in the upper tidal river in 1983 was associated with a growing-season Secchi depth of 0.86 m, total suspended solids (TSS) of 17.7 mg l−1, chlorophyll a concentrations of 15.2 μg l−1, significantly higher than average percent available sunshine, and significantly lower than average wind speed. From 1983 to 1989, mean seasonal Secchi depths \\textless0.65 m were associated with decrease in plant coverage and mean seasonal Secchi depths \\textgreater0.65 were associated with increases in plant coverage. Changes in mean seasonal Secchi depth were related to changes in mean seasonal TSS and chlorophyll a concentration; mean Secchi depths \\textgreater0.65 generally occur when seasonal mean TSS is \\textless19 mg l−1 and seasonal mean chlorophyll a concentration is ≤15 μg l−1. Secchi depth is highly correlated with plant growth in the upper tidal river and chlorophyll a and TSS with plant growth in the lower tidal river. Wind speed is an important influence on plant growth in both reaches. © 1994, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Trends in the distribution, abundance, and habitat quality of submerged aquatic vegetation in Chesapeake Bay and its tidal tributaries: 1971 to 1991 / Robert J. Orth, Richard A. Batiuk, Judith F. Nowak.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Printed by the USEnvironmental Protection Agency for the Chesapeake Bay Program, Annapolis, Md., 1994.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{orth_trends_1994,\n\taddress = {Annapolis, Md.},\n\ttitle = {Trends in the distribution, abundance, and habitat quality of submerged aquatic vegetation in {Chesapeake} {Bay} and its tidal tributaries: 1971 to 1991 / {Robert} {J}. {Orth}, {Richard} {A}. {Batiuk}, {Judith} {F}. {Nowak}.},\n\tshorttitle = {Trends in the distribution, abundance, and habitat quality of submerged aquatic vegetation in {Chesapeake} {Bay} and its tidal tributaries},\n\tabstract = {"May, 1994.", "CBP/TRS 137/95"--Cover., "EPA 903-R-95-009"--Cover., Includes bibliographical references.},\n\tlanguage = {eng},\n\tpublisher = {Printed by the USEnvironmental Protection Agency for the Chesapeake Bay Program},\n\tauthor = {Orth, Robert J.},\n\tcollaborator = {Batiuk, Richard A. and Nowak, Judith F. and {Chesapeake Bay Program}},\n\tyear = {1994},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \"May, 1994.\", \"CBP/TRS 137/95\"–Cover., \"EPA 903-R-95-009\"–Cover., Includes bibliographical references.\n
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\n \n\n \n \n \n \n \n Chesapeake Bay SAV Monitoring Program.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n In Morris, L. J.; and Tomasko, D. A., editor(s), Proceedings and conclusions of workshops on: Submerged Aquatic Vegetation Initiative and Photosynthetically Active Radiation, of Special Publication SJ93-SP13, pages 41–45. St. Johns River Water Management District, Palatka, Florida, 1993.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@incollection{orth_chesapeake_1993,\n\taddress = {Palatka, Florida},\n\tseries = {Special {Publication} {SJ93}-{SP13}},\n\ttitle = {Chesapeake {Bay} {SAV} {Monitoring} {Program}},\n\tbooktitle = {Proceedings and conclusions of workshops on: {Submerged} {Aquatic} {Vegetation} {Initiative} and {Photosynthetically} {Active} {Radiation}},\n\tpublisher = {St. Johns River Water Management District},\n\tauthor = {Orth, R. J.},\n\teditor = {Morris, L. J. and Tomasko, D. A.},\n\tyear = {1993},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {41--45},\n}\n\n
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\n \n\n \n \n \n \n \n Population dynamics of submersed macrophytes in the tidal Potomac River.\n \n \n \n\n\n \n Carter, V.; Rybicki, N. B.; and Turtora, M.\n\n\n \n\n\n\n In 25th annual meeting, Aquatic Plant Control Research Program, pages 41–53. U. S. Army Corps of Engineers, 1991.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@incollection{carter_population_1991,\n\ttitle = {Population dynamics of submersed macrophytes in the tidal {Potomac} {River}},\n\tnumber = {Misc. Paper A-91-3, Proceedings},\n\tbooktitle = {25th annual meeting, {Aquatic} {Plant} {Control} {Research} {Program}},\n\tpublisher = {U. S. Army Corps of Engineers},\n\tauthor = {Carter, V. and Rybicki, N. B. and Turtora, M.},\n\tyear = {1991},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {41--53},\n}\n\n
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\n \n\n \n \n \n \n \n Monitoring seagrass distribution and abundance patterns.\n \n \n \n\n\n \n Orth, R. J.; Ferguson, R. L.; and Haddan, K. D.\n\n\n \n\n\n\n In Bolton, H. S., editor(s), Coastal Wetlands Coastal Zone '91 Conference, pages 281–300. ASCE, Long Beach, CA, 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@incollection{orth_monitoring_1990-1,\n\taddress = {Long Beach, CA},\n\ttitle = {Monitoring seagrass distribution and abundance patterns},\n\tbooktitle = {Coastal {Wetlands} {Coastal} {Zone} '91 {Conference}},\n\tpublisher = {ASCE},\n\tauthor = {Orth, R. J. and Ferguson, R. L. and Haddan, K. D.},\n\teditor = {Bolton, H. S.},\n\tyear = {1990},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {281--300},\n}\n\n
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\n \n\n \n \n \n \n \n Monitoring seagrass distribution and abundance patterns: a case study from the Chesapeake Bay.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n of Contribution (Virginia Institute of Marine Science) no. 1576 1990.\n \n\n\n\n
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\n 
@book{orth_monitoring_1990,\n\tseries = {Contribution ({Virginia} {Institute} of {Marine} {Science}) no. 1576},\n\ttitle = {Monitoring seagrass distribution and abundance patterns: a case study from the {Chesapeake} {Bay}.},\n\tshorttitle = {Monitoring seagrass distribution and abundance patterns},\n\tabstract = {VIMS Contributions updated 6/19/2007},\n\tlanguage = {eng},\n\tauthor = {Orth, Robert J.},\n\tcollaborator = {Moore, Kenneth A. and Nowak, Judith F. and {Virginia Institute of Marine Science}},\n\tyear = {1990},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n VIMS Contributions updated 6/19/2007\n
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\n \n\n \n \n \n \n \n Data on the distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and transition zone of the Potomac Estuary, Maryland, Virginia and the District of Columbia, 1988.\n \n \n \n\n\n \n Rybicki, N. B.; and Schening, M. R.\n\n\n \n\n\n\n Technical Report 90-123, U.S. Geological Survey, Reston, Va, 1990.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@techreport{rybicki_data_1990,\n\taddress = {Reston, Va},\n\ttype = {Open-{File} {Report}},\n\ttitle = {Data on the distribution and abundance of submersed aquatic vegetation in the tidal {Potomac} {River} and transition zone of the {Potomac} {Estuary}, {Maryland}, {Virginia} and the {District} of {Columbia}, 1988},\n\tnumber = {90-123},\n\tinstitution = {U.S. Geological Survey},\n\tauthor = {Rybicki, Nancy B. and Schening, M. R.},\n\tyear = {1990},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {19},\n}\n\n
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\n \n\n \n \n \n \n \n Distribution of Zostera marina L. and Ruppia maritima L. sensu lato along depth gradients in the lower Chesapeake Bay, U.S.A.\n \n \n \n\n\n \n Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 1988.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_distribution_1988,\n\ttitle = {Distribution of {Zostera} marina {L}. and {Ruppia} maritima {L}. sensu lato along depth gradients in the lower {Chesapeake} {Bay}, {U}.{S}.{A}.},\n\tdoi = {10.1016/0304-3770(88)90122-2},\n\tabstract = {Seventeen transects in areas containing beds of submerged aquatic vegetation in the lower Chesapeake Bay were selected for analysis of the depth distribution of Ruppia maritima L. sensu lato and Zostera marina L. during a 6-week period (25 July-12 September 1978). Transects studied ranged in length from 130 to 1100 m with estimates of percent cover made on 785 plots. Mean importance value (relative frequency + relative cover) for Z. marina was 96.0 (range of 0-200) while for R. maritima it was 94.9 (0-184.4). Average cover across the beds ranged from 0 to 51.7\\% for Z. marina and 0-79.2\\% for R. maritima, with average transect biomass up to 72.9 and 55.4 g dry weight m-2 for the two species, respectively. Comparison of individual transects showed a consistent pattern of zonation where R. maritima occupied the nearshore, shallower area which graded to a mixed zone of R. maritima and Z. marina at intermediate depths. At the deepest part of the beds, Z. marina was the only species found. Transects along the western shore sites were characterized by lower percent cover with more open areas in the beds when compared with the eastern shore sites. Depth distributions of R. maritima and Z. marina on the eastern shore were +20 to -100 cm and -30 to -150 cm (mean low water (MLW)), respectively, while on the western shore they were +10 to -80 cm and +10 to -110 cm, respectively. The greater depth penetration of the two species along the eastern shore transect sites may reflect a greater influence of clearer, oceanic water compared with the more turbid, riverine influence along the western shore sites. Results demonstrate that both optimum and maximum depth limits for a species can vary considerably within a particular region and suggest the potential for marked variability over time. © 1988.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1988},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Seventeen transects in areas containing beds of submerged aquatic vegetation in the lower Chesapeake Bay were selected for analysis of the depth distribution of Ruppia maritima L. sensu lato and Zostera marina L. during a 6-week period (25 July-12 September 1978). Transects studied ranged in length from 130 to 1100 m with estimates of percent cover made on 785 plots. Mean importance value (relative frequency + relative cover) for Z. marina was 96.0 (range of 0-200) while for R. maritima it was 94.9 (0-184.4). Average cover across the beds ranged from 0 to 51.7% for Z. marina and 0-79.2% for R. maritima, with average transect biomass up to 72.9 and 55.4 g dry weight m-2 for the two species, respectively. Comparison of individual transects showed a consistent pattern of zonation where R. maritima occupied the nearshore, shallower area which graded to a mixed zone of R. maritima and Z. marina at intermediate depths. At the deepest part of the beds, Z. marina was the only species found. Transects along the western shore sites were characterized by lower percent cover with more open areas in the beds when compared with the eastern shore sites. Depth distributions of R. maritima and Z. marina on the eastern shore were +20 to -100 cm and -30 to -150 cm (mean low water (MLW)), respectively, while on the western shore they were +10 to -80 cm and +10 to -110 cm, respectively. The greater depth penetration of the two species along the eastern shore transect sites may reflect a greater influence of clearer, oceanic water compared with the more turbid, riverine influence along the western shore sites. Results demonstrate that both optimum and maximum depth limits for a species can vary considerably within a particular region and suggest the potential for marked variability over time. © 1988.\n
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\n \n\n \n \n \n \n \n Data on the distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and transition zone of the Potomac estuary, Maryland, Virginia, and the District of Columbia, 1987.\n \n \n \n\n\n \n Rybicki, N. B.; Anderson, R. T.; and Carter, V.\n\n\n \n\n\n\n Technical Report 88-307, U.S. Geological Survey, Reston, Va, 1988.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@techreport{rybicki_data_1988,\n\taddress = {Reston, Va},\n\ttype = {Open-{File} {Report}},\n\ttitle = {Data on the distribution and abundance of submersed aquatic vegetation in the tidal {Potomac} {River} and transition zone of the {Potomac} estuary, {Maryland}, {Virginia}, and the {District} of {Columbia}, 1987},\n\tnumber = {88-307},\n\tinstitution = {U.S. Geological Survey},\n\tauthor = {Rybicki, Nancy B. and Anderson, R. T. and Carter, Virginia},\n\tcollaborator = {Geological Survey (U.S.)},\n\tyear = {1988},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {31},\n}\n\n
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\n \n\n \n \n \n \n \n Submerged and emergent aquatic vegetation of the Chesapeake Bay.\n \n \n \n\n\n \n Hershner, C. H.; and Wetzel, R. L.\n\n\n \n\n\n\n In Majumdar, S. K.; Hall, L. W. J.; and Austin, H. M., editor(s), Contaminant problems and management of living Chesapeake Bay resources, pages 116–133. Pennsylvania Academy Science Typehouse of Easton, Phillipsburg, N.J., 1987.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@incollection{hershner_submerged_1987,\n\taddress = {Phillipsburg, N.J.},\n\ttitle = {Submerged and emergent aquatic vegetation of the {Chesapeake} {Bay}},\n\tbooktitle = {Contaminant problems and management of living {Chesapeake} {Bay} resources},\n\tpublisher = {Pennsylvania Academy Science Typehouse of Easton},\n\tauthor = {Hershner, C. H. and Wetzel, R. L.},\n\teditor = {Majumdar, S. K. and Hall, L. W. Jr. and Austin, H. M.},\n\tyear = {1987},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {116--133},\n}\n\n
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\n \n\n \n \n \n \n \n Grasses beneath the bay.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Virginia Wildlife, 48: 28–31. 1987.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_grasses_1987,\n\ttitle = {Grasses beneath the bay},\n\tvolume = {48},\n\tjournal = {Virginia Wildlife},\n\tauthor = {Orth, R. J.},\n\tyear = {1987},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {28--31},\n}\n\n
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\n \n\n \n \n \n \n \n Seasonal and year-to-year variations in the growth of Zostera marina L. (eelgrass) in the lower Chesapeake Bay.\n \n \n \n\n\n \n Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{orth_seasonal_1986,\n\ttitle = {Seasonal and year-to-year variations in the growth of {Zostera} marina {L}. (eelgrass) in the lower {Chesapeake} {Bay}},\n\tdoi = {10.1016/0304-3770(86)90100-2},\n\tabstract = {Seasonal and year-to-year variations in the growth of Zostera marina L. were measured at three sites in two locations in the lower Chesapeake Bay between 1978 and 1980. The maximum values for the 1979 above- and belowground standing crop ranged from 161-336 g dry wt m-2 and 61-155 g dry wt m-2, respectively, leaf length was 19.6-59.7 cm and shoot density 1418-2576 shoot m-2. Values for 1980 tended to be greater and may be related to climatical differences between the two years. Maximum values were usually recorded in the months of June and July when water temperatures were between 20 and 25°C. Significant loss of leaves occurred in July and August, when water temperatures ranged between 25 and 30°C, while new shoots began to appear more rapidly in late September as water temperatures dropped below 20°C. The greatest increase in all growth parameters occurred from April to June during which time reproductive shoots were present, and accounted for up to 25\\% of the total number of shoots. © 1986.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1986},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Seasonal and year-to-year variations in the growth of Zostera marina L. were measured at three sites in two locations in the lower Chesapeake Bay between 1978 and 1980. The maximum values for the 1979 above- and belowground standing crop ranged from 161-336 g dry wt m-2 and 61-155 g dry wt m-2, respectively, leaf length was 19.6-59.7 cm and shoot density 1418-2576 shoot m-2. Values for 1980 tended to be greater and may be related to climatical differences between the two years. Maximum values were usually recorded in the months of June and July when water temperatures were between 20 and 25°C. Significant loss of leaves occurred in July and August, when water temperatures ranged between 25 and 30°C, while new shoots began to appear more rapidly in late September as water temperatures dropped below 20°C. The greatest increase in all growth parameters occurred from April to June during which time reproductive shoots were present, and accounted for up to 25% of the total number of shoots. © 1986.\n
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\n \n\n \n \n \n \n \n Data on distribution and abundance of submersed aquatic vegetation in the tidal Potomac River, Maryland, Virginia, and the District of Columbia,1985.\n \n \n \n\n\n \n Rybicki, N. B.; Anderson, R. T.; Carter, V.; Shapiro, J. M.; and Jones, C. L.\n\n\n \n\n\n\n Technical Report 86-126, U.S. Geological Survey, Reston, Va, 1986.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@techreport{rybicki_data_1986,\n\taddress = {Reston, Va},\n\ttype = {Open-{File} {Report}},\n\ttitle = {Data on distribution and abundance of submersed aquatic vegetation in the tidal {Potomac} {River}, {Maryland}, {Virginia}, and the {District} of {Columbia},1985},\n\tnumber = {86-126},\n\tinstitution = {U.S. Geological Survey},\n\tauthor = {Rybicki, Nancy B. and Anderson, R. T. and Carter, Virginia and Shapiro, J. M. and Jones, C. L.},\n\tyear = {1986},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {49},\n}\n\n
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\n \n\n \n \n \n \n \n Distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and Estuary, Maryland and Virginia, May 1978 to November 1981. A water quality study of the tidal Potomac River and Estuary.\n \n \n \n\n\n \n Carter, V.; Paschal, J. E.; and Bartow, N.\n\n\n \n\n\n\n US Geological Survey Water-Supply Paper. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carter_distribution_1985,\n\ttitle = {Distribution and abundance of submersed aquatic vegetation in the tidal {Potomac} {River} and {Estuary}, {Maryland} and {Virginia}, {May} 1978 to {November} 1981. {A} water quality study of the tidal {Potomac} {River} and {Estuary}.},\n\tdoi = {10.3133/wsp2234A},\n\tabstract = {Identified, 14 vascular plants and 2 species of the alga Chara. Vallisneria americana, Zannichellia palustris, Ruppia maritima and Potamogeton perfoliatus were the most abundant and widespread species. The present distribution and abundance differ considerably from that in the early 1900s when flats in the tidal river were covered with lush vegetation including Vallisneria and Potamogeton spp., and the estuary had an abundance of Zostera marina. The most likely reasons for the almost complete disappearance of these plants from the tidal river include extensive storm damage in the 1930s; increasing nutrient enrichment with a shift in the relationship or balance between submersed aquatic plants and phytoplankton; a change in light availability; and grazing by turtles, fish, muskrat or waterfowl before an adequate rhizome mat or minimum bed size is established. Salinity dynamics in the transition zone may account for the presence of abundant vegetation and the diversity of species in this area. -from Authors},\n\tjournal = {US Geological Survey Water-Supply Paper},\n\tauthor = {Carter, V. and Paschal, J. E. and Bartow, N.},\n\tyear = {1985},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
\n\n\n
\n Identified, 14 vascular plants and 2 species of the alga Chara. Vallisneria americana, Zannichellia palustris, Ruppia maritima and Potamogeton perfoliatus were the most abundant and widespread species. The present distribution and abundance differ considerably from that in the early 1900s when flats in the tidal river were covered with lush vegetation including Vallisneria and Potamogeton spp., and the estuary had an abundance of Zostera marina. The most likely reasons for the almost complete disappearance of these plants from the tidal river include extensive storm damage in the 1930s; increasing nutrient enrichment with a shift in the relationship or balance between submersed aquatic plants and phytoplankton; a change in light availability; and grazing by turtles, fish, muskrat or waterfowl before an adequate rhizome mat or minimum bed size is established. Salinity dynamics in the transition zone may account for the presence of abundant vegetation and the diversity of species in this area. -from Authors\n
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\n \n\n \n \n \n \n \n Historical changes in submerged macrophyte communities of upper Chesapeake Bay.\n \n \n \n\n\n \n Davis, F. W.\n\n\n \n\n\n\n Ecology. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{davis_historical_1985,\n\ttitle = {Historical changes in submerged macrophyte communities of upper {Chesapeake} {Bay}.},\n\tdoi = {10.2307/1940560},\n\tabstract = {Submerged macrophyte species that occurred at the head of Chesapeake Bay over the past 1800 yr were documented by analyzing seed assemblages in sediments from a tidal embayment. Estuarine seed assemblages are primarily locally derived and have high spatial variability. Because of differences in seed output or preservation some species are overrepresented in the seed record. The record of local submerged macrophytes was profiled in 7-100 yr intervals, using sediment dates obtained radiometrically and by pollen stratigraphy. Vallisneria americana, Najas flexilis, N. gracillima and Elodea canadensis were consistently present for 1500-1600 yr prior to colonization by Europeans (1730 AD), while N. guadelupensis appeared 300-400 yr prior to European settlement. Vallisneria americana was the only local species continuously present for 150 yr following initial deforestation. After 1930, N. guadalupensis and N. flexilis appeared more regularly in the record, and two local expansions of Myriophyllum spicatum were registered. Native submerged aquatic vegetation disappeared from the area between 1964-1972, and has shown little recovery since that time. Community changes after 1930 appear to be related to increased eutrophication.-from Author},\n\tjournal = {Ecology},\n\tauthor = {Davis, F. W.},\n\tyear = {1985},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
\n
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\n Submerged macrophyte species that occurred at the head of Chesapeake Bay over the past 1800 yr were documented by analyzing seed assemblages in sediments from a tidal embayment. Estuarine seed assemblages are primarily locally derived and have high spatial variability. Because of differences in seed output or preservation some species are overrepresented in the seed record. The record of local submerged macrophytes was profiled in 7-100 yr intervals, using sediment dates obtained radiometrically and by pollen stratigraphy. Vallisneria americana, Najas flexilis, N. gracillima and Elodea canadensis were consistently present for 1500-1600 yr prior to colonization by Europeans (1730 AD), while N. guadelupensis appeared 300-400 yr prior to European settlement. Vallisneria americana was the only local species continuously present for 150 yr following initial deforestation. After 1930, N. guadalupensis and N. flexilis appeared more regularly in the record, and two local expansions of Myriophyllum spicatum were registered. Native submerged aquatic vegetation disappeared from the area between 1964-1972, and has shown little recovery since that time. Community changes after 1930 appear to be related to increased eutrophication.-from Author\n
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\n \n\n \n \n \n \n \n Data on distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and transition zone of the Potomac River, Maryland, Virginia and the District of Columbia, 1983 and 1984.\n \n \n \n\n\n \n Carter, V.; Rybicki, N. B.; Anderson, R. T.; Trombley, T. J.; and Zynjuk, G. L.\n\n\n \n\n\n\n Technical Report 85-82, U.S. Geological Survey, Reston, Va, 1985.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@techreport{carter_data_1985,\n\taddress = {Reston, Va},\n\ttype = {Open-{File} {Report}},\n\ttitle = {Data on distribution and abundance of submersed aquatic vegetation in the tidal {Potomac} {River} and transition zone of the {Potomac} {River}, {Maryland}, {Virginia} and the {District} of {Columbia}, 1983 and 1984},\n\tnumber = {85-82},\n\tinstitution = {U.S. Geological Survey},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B. and Anderson, R. T. and Trombley, T. J. and Zynjuk, G. L.},\n\tyear = {1985},\n\tkeywords = {Distribution, Abundance, and Production},\n\tpages = {61},\n}\n\n
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\n \n\n \n \n \n \n \n Distribution and abundance of submerged aquatic vegetation in Chesapeake Bay: An historical perspective.\n \n \n \n\n\n \n Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Estuaries. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_distribution_1984,\n\ttitle = {Distribution and abundance of submerged aquatic vegetation in {Chesapeake} {Bay}: {An} historical perspective},\n\tdoi = {10.2307/1352058},\n\tabstract = {An historical summary of the distribution and abundance of submerged aquatic vegetation (SAV) in the Chesapeake Bay is presented. Evidence suggests that SAV has generally been common throughout the bay over the last several hundred years with several fluctuations in abundance. The decline of Zostera marina (eelgrass) in the 1930's and the rapid expansion of Myriophyllum spicatum (watermilfoil) in the late 1950's and early 1960's were two significant events involving a single species. Since 1965, however, there has been a significant reduction of all species in most sections of the bay. Declines were first observed in the Patuxent, Potomac and sections of other rivers in the Maryland portion of the Bay between 1965 and 1970. Dramatic reductions were observed over the entire length of the bay from 1970 to 1975. Particularly severe losses were observed at the head of the bay around Susquehanna Flats as well as in numerous rivers along Maryland's eastern and western shores. Changes in the lower, Virginia portion of the bay occurred primarily in the western tributaries. Greatest losses of vegetation occurred in the years following Tropical Storm Agnes in 1972. Since 1975 little regrowth has been observed in the Chesapeake Bay. Other areas along the Atlantic Coast of the U.S. during the same period have experienced no similar widespread decline. It thus appears that the factors affecting the recent changes in distribution and abundance of submerged vegetation in the bay are regional in nature. Causes for this decline may be related to changes in water quality, primarily increased eutrophication and turbidity. © 1984, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1984},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n An historical summary of the distribution and abundance of submerged aquatic vegetation (SAV) in the Chesapeake Bay is presented. Evidence suggests that SAV has generally been common throughout the bay over the last several hundred years with several fluctuations in abundance. The decline of Zostera marina (eelgrass) in the 1930's and the rapid expansion of Myriophyllum spicatum (watermilfoil) in the late 1950's and early 1960's were two significant events involving a single species. Since 1965, however, there has been a significant reduction of all species in most sections of the bay. Declines were first observed in the Patuxent, Potomac and sections of other rivers in the Maryland portion of the Bay between 1965 and 1970. Dramatic reductions were observed over the entire length of the bay from 1970 to 1975. Particularly severe losses were observed at the head of the bay around Susquehanna Flats as well as in numerous rivers along Maryland's eastern and western shores. Changes in the lower, Virginia portion of the bay occurred primarily in the western tributaries. Greatest losses of vegetation occurred in the years following Tropical Storm Agnes in 1972. Since 1975 little regrowth has been observed in the Chesapeake Bay. Other areas along the Atlantic Coast of the U.S. during the same period have experienced no similar widespread decline. It thus appears that the factors affecting the recent changes in distribution and abundance of submerged vegetation in the bay are regional in nature. Causes for this decline may be related to changes in water quality, primarily increased eutrophication and turbidity. © 1984, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Hydrilla invades Washington, D.C. and the Potomac.\n \n \n \n\n\n \n Steward, K. K.; Van, T. K.; Carter, V.; and Pieterse, A. H.\n\n\n \n\n\n\n American Journal of Botany. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{steward_hydrilla_1984,\n\ttitle = {Hydrilla invades {Washington}, {D}.{C}. and the {Potomac}.},\n\tdoi = {10.2307/2443637},\n\tabstract = {The aquatic weed Hydrilla verticillata was discovered growing in the Potomac River, south of Alexandria, VA, in Kenilworth Aquatic Gardens, Washington, DC, and in the Chesapeake and Ohio Canal near Seneca, MD. This is the first report of the occurrence of the male in the US. The occurrence of the wild colonies of the monoecious Hydrilla greatly increases the potential for physiological diversity through sexual reproduction, which may have serious consequences for the management of this weed. -from Authors},\n\tjournal = {American Journal of Botany},\n\tauthor = {Steward, K. K. and Van, T. K. and Carter, V. and Pieterse, A. H.},\n\tyear = {1984},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n The aquatic weed Hydrilla verticillata was discovered growing in the Potomac River, south of Alexandria, VA, in Kenilworth Aquatic Gardens, Washington, DC, and in the Chesapeake and Ohio Canal near Seneca, MD. This is the first report of the occurrence of the male in the US. The occurrence of the wild colonies of the monoecious Hydrilla greatly increases the potential for physiological diversity through sexual reproduction, which may have serious consequences for the management of this weed. -from Authors\n
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\n \n\n \n \n \n \n \n Chesapeake Bay: An unprecedented decline in submerged aquatic vegetation.\n \n \n \n\n\n \n Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Science. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_chesapeake_1983,\n\ttitle = {Chesapeake {Bay}: {An} unprecedented decline in submerged aquatic vegetation},\n\tdoi = {10.1126/science.222.4619.51},\n\tabstract = {Data on the distribution and abundance of submerged aquatic vegetation in Chesapeake Bay indicate a significant reduction in all species in all sections of the bay during the last 15 to 20 years. This decline is unprecedented in the bay's recent history, the reduction in one major species, Zostera marina, may be greater than the decline that occurred during the pandemic demise of the 1930's.},\n\tjournal = {Science},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1983},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Data on the distribution and abundance of submerged aquatic vegetation in Chesapeake Bay indicate a significant reduction in all species in all sections of the bay during the last 15 to 20 years. This decline is unprecedented in the bay's recent history, the reduction in one major species, Zostera marina, may be greater than the decline that occurred during the pandemic demise of the 1930's.\n
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\n \n\n \n \n \n \n \n Distribution of submersed aquatic macrophytes in the tidal Potomac River.\n \n \n \n\n\n \n Haramis, G. M.; and Carter, V.\n\n\n \n\n\n\n Aquatic Botany. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{haramis_distribution_1983,\n\ttitle = {Distribution of submersed aquatic macrophytes in the tidal {Potomac} {River}},\n\tdoi = {10.1016/0304-3770(83)90100-6},\n\tabstract = {Results of a 3-year survey (1978-1980) and review of historic trends have shown a major decline in the number of species and the distribution of submersed aquatic macrophytes in the tidal Potomac River since the early 1900's. The freshwater tidal river is essentially devoid of plants and only very sparse populations remain in the mesohaline section of the estuary. Present plant populations are largely confined to the transition-zone region where salinity instability at the fresh-to-brackish water interface is believed to reduce biotic stress on submersed vegetation. Many factors may be implicated in the loss of vegetation over major regions of the tidal Potomac River; however, long-term conditions of excessive nutrients appear to be primarily responsible for the present distribution. © 1983.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Haramis, G. M. and Carter, V.},\n\tyear = {1983},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Results of a 3-year survey (1978-1980) and review of historic trends have shown a major decline in the number of species and the distribution of submersed aquatic macrophytes in the tidal Potomac River since the early 1900's. The freshwater tidal river is essentially devoid of plants and only very sparse populations remain in the mesohaline section of the estuary. Present plant populations are largely confined to the transition-zone region where salinity instability at the fresh-to-brackish water interface is believed to reduce biotic stress on submersed vegetation. Many factors may be implicated in the loss of vegetation over major regions of the tidal Potomac River; however, long-term conditions of excessive nutrients appear to be primarily responsible for the present distribution. © 1983.\n
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\n \n\n \n \n \n \n \n SUBMERSED VASCULAR PLANTS: TECHNIQUES FOR ANALYZING THEIR DISTRIBUTION AND ABUNDANCE.\n \n \n \n\n\n \n Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Marine Technology Society Journal. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{orth_submersed_1983,\n\ttitle = {{SUBMERSED} {VASCULAR} {PLANTS}: {TECHNIQUES} {FOR} {ANALYZING} {THEIR} {DISTRIBUTION} {AND} {ABUNDANCE}.},\n\tabstract = {Grass beds appearing as distinct features in imagery can be mapped and areal distributions computed. The acquisition of adequate imagery depends on sun angle, wind velocity, and cloud cover. A combination of remote sensing information and field survey data enables productive analysis of the distribution and abundance of submersed vascular plants.},\n\tjournal = {Marine Technology Society Journal},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1983},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Grass beds appearing as distinct features in imagery can be mapped and areal distributions computed. The acquisition of adequate imagery depends on sun angle, wind velocity, and cloud cover. A combination of remote sensing information and field survey data enables productive analysis of the distribution and abundance of submersed vascular plants.\n
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\n \n\n \n \n \n \n \n The biology and propagation of eelgrass, Zostera marina, in Chesapeake Bay.\n \n \n \n\n\n \n Orth, R J; and Moore, K A\n\n\n \n\n\n\n U.S. EPA. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{orth_biology_1983,\n\ttitle = {The biology and propagation of eelgrass, {Zostera} marina, in {Chesapeake} {Bay}},\n\tabstract = {Basic biological aspects related to the growth and propagation of eelgrass in the lower Chesapeake Bay were studied in a series of six experiments. These were designed to reveal information on seasonal aspects of standing crops, reproduction, transplanting, and spontaneous revegetation in denuded areas, and growth of eelgrass seedlings under laboratory conditions of increased nutrient enrichment.},\n\tjournal = {U.S. EPA},\n\tauthor = {Orth, R J and Moore, K A},\n\tyear = {1983},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Basic biological aspects related to the growth and propagation of eelgrass in the lower Chesapeake Bay were studied in a series of six experiments. These were designed to reveal information on seasonal aspects of standing crops, reproduction, transplanting, and spontaneous revegetation in denuded areas, and growth of eelgrass seedlings under laboratory conditions of increased nutrient enrichment.\n
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\n \n\n \n \n \n \n \n Submerged aquatic vegetation: distribution and abundance in the lower Chesapeake Bay and the interactive effects of light, epiphytes, and grazers.\n \n \n \n\n\n \n Orth, R J; Moore, K A; and Montfrans, J V\n\n\n \n\n\n\n U.S. EPA. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_submerged_1983,\n\ttitle = {Submerged aquatic vegetation: distribution and abundance in the lower {Chesapeake} {Bay} and the interactive effects of light, epiphytes, and grazers},\n\tabstract = {Submerged aquatic vegetation a major ecological resource, has undergone a major decline in Chesapeake Bay during the past decade. A literature review of the relationship between epiphytic fouling by macroalgae and periphyton and the grazers that feed on these epiphytes indicates that grazing plays a major role in preventing over-growth of epiphytes. Nutrient enrichment can stimulate the excessive growth of epiphytes, resulting in death of the plants. The salinity tolerances of one major grazer, the snail Bittium varium, were studied to determine whether rapid fresh-water influx would prove fatal to the snail. Studies of plant vigor, under three shading conditions, in the presence and absence of Bittium varium, indicated that within each shading condition plant vigor was enhanced by the presence of the snail.},\n\tjournal = {U.S. EPA},\n\tauthor = {Orth, R J and Moore, K A and Montfrans, J V},\n\tyear = {1983},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n\n\n
\n Submerged aquatic vegetation a major ecological resource, has undergone a major decline in Chesapeake Bay during the past decade. A literature review of the relationship between epiphytic fouling by macroalgae and periphyton and the grazers that feed on these epiphytes indicates that grazing plays a major role in preventing over-growth of epiphytes. Nutrient enrichment can stimulate the excessive growth of epiphytes, resulting in death of the plants. The salinity tolerances of one major grazer, the snail Bittium varium, were studied to determine whether rapid fresh-water influx would prove fatal to the snail. Studies of plant vigor, under three shading conditions, in the presence and absence of Bittium varium, indicated that within each shading condition plant vigor was enhanced by the presence of the snail.\n
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\n \n\n \n \n \n \n \n Distribution and abundance of waterfowl and submerged aquatic vegetation in Chesapeake Bay.\n \n \n \n\n\n \n Munro, R. E.; and Perry, M. C.\n\n\n \n\n\n\n Technical Report US Environmental Protection Agency, 1982.\n \n\n\n\n
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@techreport{munro_distribution_1982,\n\ttitle = {Distribution and abundance of waterfowl and submerged aquatic vegetation in {Chesapeake} {Bay}},\n\tinstitution = {US Environmental Protection Agency},\n\tauthor = {Munro, Robert E. and Perry, Matthew C.},\n\tyear = {1982},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n SUBMERSED AQUATIC VEGETATION IN THE TIDAL POTOMAC.\n \n \n \n\n\n \n Carter, V.; Paschal, J. E.; and Haramis, G. M.\n\n\n \n\n\n\n In Proceedings of SOUTHEASTCON Region 3 Conference, 1980. \n \n\n\n\n
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@inproceedings{carter_submersed_1980,\n\ttitle = {{SUBMERSED} {AQUATIC} {VEGETATION} {IN} {THE} {TIDAL} {POTOMAC}.},\n\tabstract = {The results of a continuing survey, begun in 1978, show that submersed aquatic vegetation is distributed unevenly in the tidal Potomac River. The largest and most diverse aquatic plant populations are found in the transition zone where freshwater and saltwater mix. This distribution is very different from that reported near the turn of the century. The factors that might cause thie unusual distribution, and the decline of submersed aquatic vegetation in general, include nutrient loading, increased sedimentation rates, substrate composition, and various types of chemical pollution associated with human population growth. The decline of plants in the freshwater tidal river and in other freshwater ecosystems indicates environmental imbalance. Refs.},\n\tbooktitle = {Proceedings of {SOUTHEASTCON} {Region} 3 {Conference}},\n\tauthor = {Carter, Virginia and Paschal, James E. and Haramis, G. Michael},\n\tyear = {1980},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n The results of a continuing survey, begun in 1978, show that submersed aquatic vegetation is distributed unevenly in the tidal Potomac River. The largest and most diverse aquatic plant populations are found in the transition zone where freshwater and saltwater mix. This distribution is very different from that reported near the turn of the century. The factors that might cause thie unusual distribution, and the decline of submersed aquatic vegetation in general, include nutrient loading, increased sedimentation rates, substrate composition, and various types of chemical pollution associated with human population growth. The decline of plants in the freshwater tidal river and in other freshwater ecosystems indicates environmental imbalance. Refs.\n
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\n \n\n \n \n \n \n \n Changes in submerged aquatic macrophyte populations at the head of Chesapeake Bay, 1958–1975.\n \n \n \n\n\n \n Bayley, S.; Stotts, V. D.; Springer, P. F.; and Steenis, J.\n\n\n \n\n\n\n Estuaries. 1978.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{bayley_changes_1978,\n\ttitle = {Changes in submerged aquatic macrophyte populations at the head of {Chesapeake} {Bay}, 1958–1975},\n\tdoi = {10.2307/1351459},\n\tabstract = {Submerged aquatic plant populations in the Susquehanna Flats of the Chesapeake Bay were followed for 18 years. An exotic species, eurasian water milfoil, Myriophyllum spicatum, increased dramatically from 1958 to 1962; at the same time the dominant native species declined. After 1962, milfoil populations declined and the native rooted aquatics gradually began to return to their former levels. In the late 1960's all species declined and in 1972 almost disappeared from the Susquehanna Flats. These fluctuations may have been related to several interrelated environmental factors in the Chesapeake Bay, including tropical storms, turbidity, salinity and disease. The utilization of the Susquehanna Flats by waterfowl appears to be related to the abundance and species composition of the submerged macrophytes present. © 1978, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Bayley, Suzanne and Stotts, Vernon D. and Springer, Paul F. and Steenis, John},\n\tyear = {1978},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Submerged aquatic plant populations in the Susquehanna Flats of the Chesapeake Bay were followed for 18 years. An exotic species, eurasian water milfoil, Myriophyllum spicatum, increased dramatically from 1958 to 1962; at the same time the dominant native species declined. After 1962, milfoil populations declined and the native rooted aquatics gradually began to return to their former levels. In the late 1960's all species declined and in 1972 almost disappeared from the Susquehanna Flats. These fluctuations may have been related to several interrelated environmental factors in the Chesapeake Bay, including tropical storms, turbidity, salinity and disease. The utilization of the Susquehanna Flats by waterfowl appears to be related to the abundance and species composition of the submerged macrophytes present. © 1978, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n The demise and recovery of eelgrass, Zostera marina, in the Chesapeake Bay, Virginia.\n \n \n \n\n\n \n Orth, R.\n\n\n \n\n\n\n Aquatic Botany. 1976.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{orth_demise_1976,\n\ttitle = {The demise and recovery of eelgrass, {Zostera} marina, in the {Chesapeake} {Bay}, {Virginia}},\n\tdoi = {10.1016/0304-3770(76)90016-4},\n\tabstract = {Eelgrass, Zostera marina L., has been undergoing major flutuations in abundance in the Chesapeake Bay in the last 3 years. Evidence from aerial photographs and ground truth reconnaissance indicated a major loss of Zostera in the summer of 1973. Recolonization by seedlings resulted in the recovery of some areas, but there was an overall reduction of Zostera in the lower Chesapeake Bay of 36\\% from 1971 to 1974. Examination of the Zostera beds in November, 1975, indicated a virtual absence of all Zostera in the Bay area. © 1976.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert},\n\tyear = {1976},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Eelgrass, Zostera marina L., has been undergoing major flutuations in abundance in the Chesapeake Bay in the last 3 years. Evidence from aerial photographs and ground truth reconnaissance indicated a major loss of Zostera in the summer of 1973. Recolonization by seedlings resulted in the recovery of some areas, but there was an overall reduction of Zostera in the lower Chesapeake Bay of 36% from 1971 to 1974. Examination of the Zostera beds in November, 1975, indicated a virtual absence of all Zostera in the Bay area. © 1976.\n
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\n \n\n \n \n \n \n \n Abundance of submerged vascular vegetation in the Rhode River from 1966 to 1973.\n \n \n \n\n\n \n Southwick, C. H.; and Pine, F. W.\n\n\n \n\n\n\n Chesapeake Science. 1975.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{southwick_abundance_1975,\n\ttitle = {Abundance of submerged vascular vegetation in the {Rhode} {River} from 1966 to 1973},\n\tdoi = {10.2307/1350694},\n\tabstract = {Surveys on the distribution and abundance of submerged vascular plants in the Rhode River showed that there was an irregular decline in the amount of vegetation from 1966 to 1973, along with significant changes in species dominance. In 1966, redheadgrass (Potamogeton perfoliatus) and Eurasian watermilfoil (Myriophyllum spicatum) were both very abundant with lesser amounts of widgeongrass (Ruppia maritima), horned pondweed (Zannichellia palustris), sago pondweed (Potamogeton pectinatus), and elodea (Elodea canadensis). In 1967, all of these species declined substantially, and elodea disappeared entirely. In 1968, redhead-grass and horned pondweed returned in substantial abundance, but they again declined in 1969 and virtually all submerged aquatics disappeared in 1970. In 1972, horned pondweed and sago pondweed reached an eight-year peak, but other species remained at very low levels. In 1973, all species were low, and a prominent lack of vegatation similar to 1967, 1970, and 1971 occurred again. Elodea has not been seen in the Rhode River since 1966. We believe these changes represent a decline in environmental quality in the Rhode River that may have serious longrange implications. © 1975, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Southwick, Charles H. and Pine, Frank W.},\n\tyear = {1975},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n Surveys on the distribution and abundance of submerged vascular plants in the Rhode River showed that there was an irregular decline in the amount of vegetation from 1966 to 1973, along with significant changes in species dominance. In 1966, redheadgrass (Potamogeton perfoliatus) and Eurasian watermilfoil (Myriophyllum spicatum) were both very abundant with lesser amounts of widgeongrass (Ruppia maritima), horned pondweed (Zannichellia palustris), sago pondweed (Potamogeton pectinatus), and elodea (Elodea canadensis). In 1967, all of these species declined substantially, and elodea disappeared entirely. In 1968, redhead-grass and horned pondweed returned in substantial abundance, but they again declined in 1969 and virtually all submerged aquatics disappeared in 1970. In 1972, horned pondweed and sago pondweed reached an eight-year peak, but other species remained at very low levels. In 1973, all species were low, and a prominent lack of vegatation similar to 1967, 1970, and 1971 occurred again. Elodea has not been seen in the Rhode River since 1966. We believe these changes represent a decline in environmental quality in the Rhode River that may have serious longrange implications. © 1975, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n Tentative outline for inventory of aquatic vegetation: Myriophyllum spicatum (Eurasian watermilfoil).\n \n \n \n\n\n \n Southwick, C. H.\n\n\n \n\n\n\n Chesapeake Science. 1972.\n \n\n\n\n
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@article{southwick_tentative_1972,\n\ttitle = {Tentative outline for inventory of aquatic vegetation: {Myriophyllum} spicatum ({Eurasian} watermilfoil)},\n\tdoi = {10.2307/1350677},\n\tjournal = {Chesapeake Science},\n\tauthor = {Southwick, C. H.},\n\tyear = {1972},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Submerged vascular plants of the Chesapeake Bay and tributaries.\n \n \n \n\n\n \n Anderson, R. R.\n\n\n \n\n\n\n Chesapeake Science. 1972.\n \n\n\n\n
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@article{anderson_submerged_1972,\n\ttitle = {Submerged vascular plants of the {Chesapeake} {Bay} and tributaries},\n\tdoi = {10.2307/1350651},\n\tjournal = {Chesapeake Science},\n\tauthor = {Anderson, Richard R.},\n\tyear = {1972},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n \n\n \n \n \n \n \n Ecological studies of transition-zone vascular plants in South River, Maryland.\n \n \n \n\n\n \n Philipp, C. C.; and Brown, R. G.\n\n\n \n\n\n\n Chesapeake Science. 1965.\n \n\n\n\n
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@article{philipp_ecological_1965,\n\ttitle = {Ecological studies of transition-zone vascular plants in {South} {River}, {Maryland}},\n\tdoi = {10.2307/1351322},\n\tabstract = {The distribution of aquatic vascular plants in two transition areas was studied on the South River, an estuarine branch of the Chesapeake Bay located in Anne Arundel County, Maryland (N 38°54′, W 76°20′). One transition area was near the mouth of the river, where salinities were constantly high due to the proximity of Chesapeake Bay. The other area was at the headwaters of the river, where salinities were lower and without diurnal variation. Temperature, pH, surface currents, and tide levels were measured. Laboratory analyses included three of the major cations in the water, calcium, sodium, and potassium. The dominant species at the mouth of the river were Myriophyllum spicatum, Potamogeton perfoliatus, Elodea Nuttallii, and Spartina alterniflora. The dominant species found at the headwaters were Elodea canadensis, Typha angustifolia, Pontederia lanceolata, Peltandra virginica, and species of the genus Sagittaria. © 1965 Estuarine Research Federation.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Philipp, Charles C. and Brown, Russell G.},\n\tyear = {1965},\n\tkeywords = {Distribution, Abundance, and Production},\n}\n\n
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\n The distribution of aquatic vascular plants in two transition areas was studied on the South River, an estuarine branch of the Chesapeake Bay located in Anne Arundel County, Maryland (N 38°54′, W 76°20′). One transition area was near the mouth of the river, where salinities were constantly high due to the proximity of Chesapeake Bay. The other area was at the headwaters of the river, where salinities were lower and without diurnal variation. Temperature, pH, surface currents, and tide levels were measured. Laboratory analyses included three of the major cations in the water, calcium, sodium, and potassium. The dominant species at the mouth of the river were Myriophyllum spicatum, Potamogeton perfoliatus, Elodea Nuttallii, and Spartina alterniflora. The dominant species found at the headwaters were Elodea canadensis, Typha angustifolia, Pontederia lanceolata, Peltandra virginica, and species of the genus Sagittaria. © 1965 Estuarine Research Federation.\n
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\n  \n Environmental Interactions, Processes, and Modeling\n \n \n (119)\n \n \n
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\n \n\n \n \n \n \n \n Adaptations by Zostera marina dominated seagrass meadows in response towater quality and climate forcing.\n \n \n \n\n\n \n Shields, E. C.; Moore, K. A.; and Parrish, D. B.\n\n\n \n\n\n\n Diversity. 2018.\n \n\n\n\n
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@article{shields_adaptations_2018-1,\n\ttitle = {Adaptations by {Zostera} marina dominated seagrass meadows in response towater quality and climate forcing},\n\tdoi = {10.3390/d10040125},\n\tabstract = {Global assessments of seagrass declines have documented accelerating rates of loss due to anthropogenic sediment and nutrient loadings, resulting in poor water quality. More recently, global temperature increases have emerged as additional major stressors. Seagrass changes in the Chesapeake Bay, USA provide important examples of not only the effects of human disturbance and climate forcing on seagrass loss, but also meadow recovery and resiliency. In the York River sub-tributary of the Chesapeake Bay, the meadows have been monitored intensively using annual aerial imagery, monthly transect surveys, and continuous water quality measurements. Here, Zostera marina has been demonstrating a shift in its historical growth patterns, with its biomass peaking earlier in the growing season and summer declines beginning earlier. We found an increasing trend in the length of the most stressful high temperature summer period, increasing by 22 days since 1950. Over the past 20 years, Z. marina's abundance has exhibited periods of decline followed by recovery, with recovery years associated with greater spring water clarity and less time spent at water temperatures {\\textbackslash}textgreater 28 °C. Although human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina.},\n\tjournal = {Diversity},\n\tauthor = {Shields, Erin C. and Moore, Kenneth A. and Parrish, David B.},\n\tyear = {2018},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Global assessments of seagrass declines have documented accelerating rates of loss due to anthropogenic sediment and nutrient loadings, resulting in poor water quality. More recently, global temperature increases have emerged as additional major stressors. Seagrass changes in the Chesapeake Bay, USA provide important examples of not only the effects of human disturbance and climate forcing on seagrass loss, but also meadow recovery and resiliency. In the York River sub-tributary of the Chesapeake Bay, the meadows have been monitored intensively using annual aerial imagery, monthly transect surveys, and continuous water quality measurements. Here, Zostera marina has been demonstrating a shift in its historical growth patterns, with its biomass peaking earlier in the growing season and summer declines beginning earlier. We found an increasing trend in the length of the most stressful high temperature summer period, increasing by 22 days since 1950. Over the past 20 years, Z. marina's abundance has exhibited periods of decline followed by recovery, with recovery years associated with greater spring water clarity and less time spent at water temperatures \\textgreater 28 °C. Although human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina.\n
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\n \n\n \n \n \n \n \n Warming temperatures alter the relative abundance and distribution of two co-occurring foundational seagrasses in chesapeake bay, USA.\n \n \n \n\n\n \n Paul Richardson, J.; Lefcheck, J. S.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2018.\n \n\n\n\n
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@article{paul_richardson_warming_2018,\n\ttitle = {Warming temperatures alter the relative abundance and distribution of two co-occurring foundational seagrasses in chesapeake bay, {USA}},\n\tdoi = {10.3354/meps12620},\n\tabstract = {Climate change has the potential to alter the abundance and distribution of coastal foundational species worldwide through range expansions. However, there is comparatively little evidence to show how climate change may alter interactions between foundational species that already co-occur. Here, we use long-term environmental monitoring data and non-parametric models to identify the factors driving the local cover of 2 co-existing foundational seagrasses, Zostera marina and Ruppia maritima, across 38 non-consecutive years in Chesapeake Bay, USA. We show, from an analysis of cover along permanent transects in the lower, polyhaline areas of the bay, an altered relationship between the abundance of these 2 species through time and space: mean cover on these transects of Z. marina was 47\\% in the 1990s, declined to 19\\% in the 2000s, and further declined to 17\\% in the 2010s, indicating a general decline of about 64\\% over the past 3 decades. In contrast, R. maritima cover was generally lower and less variable than Z. marina cover and increased from 6.8\\% in the 1990s to 7.5\\% in the 2000s and finally to 11.4\\% in the 2010s. Generalized additive models revealed that, after accounting for other environmental covariates, the cover of one species was strongly influenced by the cover of the other. The dominance of Z. marina over R. maritima was further modulated by rising temperatures. Thus, we propose that climate change may mediate the distributional patterns of these 2 species to the detriment of Z. marina and the benefit of R. maritima.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Paul Richardson, J. and Lefcheck, Jonathan S. and Orth, Robert J.},\n\tyear = {2018},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Climate change has the potential to alter the abundance and distribution of coastal foundational species worldwide through range expansions. However, there is comparatively little evidence to show how climate change may alter interactions between foundational species that already co-occur. Here, we use long-term environmental monitoring data and non-parametric models to identify the factors driving the local cover of 2 co-existing foundational seagrasses, Zostera marina and Ruppia maritima, across 38 non-consecutive years in Chesapeake Bay, USA. We show, from an analysis of cover along permanent transects in the lower, polyhaline areas of the bay, an altered relationship between the abundance of these 2 species through time and space: mean cover on these transects of Z. marina was 47% in the 1990s, declined to 19% in the 2000s, and further declined to 17% in the 2010s, indicating a general decline of about 64% over the past 3 decades. In contrast, R. maritima cover was generally lower and less variable than Z. marina cover and increased from 6.8% in the 1990s to 7.5% in the 2000s and finally to 11.4% in the 2010s. Generalized additive models revealed that, after accounting for other environmental covariates, the cover of one species was strongly influenced by the cover of the other. The dominance of Z. marina over R. maritima was further modulated by rising temperatures. Thus, we propose that climate change may mediate the distributional patterns of these 2 species to the detriment of Z. marina and the benefit of R. maritima.\n
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\n \n\n \n \n \n \n \n Submersed aquatic vegetation in chesapeake bay: Sentinel species in a changing world.\n \n \n \n\n\n \n Orth, R. J.; Dennison, W. C.; Lefcheck, J. S.; Gurbisz, C.; Hannam, M.; Keisman, J.; Landry, J. B.; Moore, K. A.; Murphy, R. R.; Patrick, C. J.; Testa, J.; Weller, D. E.; and Wilcox, D. J.\n\n\n \n\n\n\n 2017.\n Publication Title: BioScience\n\n\n\n
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@book{orth_submersed_2017,\n\ttitle = {Submersed aquatic vegetation in chesapeake bay: {Sentinel} species in a changing world},\n\tabstract = {Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.},\n\tauthor = {Orth, Robert J. and Dennison, William C. and Lefcheck, Jonathan S. and Gurbisz, Cassie and Hannam, Michael and Keisman, Jennifer and Landry, J. Brooke and Moore, Kenneth A. and Murphy, Rebecca R. and Patrick, Christopher J. and Testa, Jeremy and Weller, Donald E. and Wilcox, David J.},\n\tyear = {2017},\n\tdoi = {10.1093/biosci/bix058},\n\tnote = {Publication Title: BioScience},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.\n
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\n \n\n \n \n \n \n \n Multiple stressors threaten the imperiled coastal foundation species eelgrass (Zostera marina) in Chesapeake Bay, USA.\n \n \n \n\n\n \n Lefcheck, J. S.; Wilcox, D. J.; Murphy, R. R.; Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Global Change Biology. 2017.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{lefcheck_multiple_2017,\n\ttitle = {Multiple stressors threaten the imperiled coastal foundation species eelgrass ({Zostera} marina) in {Chesapeake} {Bay}, {USA}},\n\tdoi = {10.1111/gcb.13623},\n\tabstract = {Interactions among global change stressors and their effects at large scales are often proposed, but seldom evaluated. This situation is primarily due to lack of comprehensive, sufficiently long-term, and spatially extensive datasets. Seagrasses, which provide nursery habitat, improve water quality, and constitute a globally important carbon sink, are among the most vulnerable habitats on the planet. Here, we unite 31 years of high-resolution aerial monitoring and water quality data to elucidate the patterns and drivers of eelgrass (Zostera marina) abundance in Chesapeake Bay, USA, one of the largest and most valuable estuaries in the world, with an unparalleled history of regulatory efforts. We show that eelgrass area has declined 29\\% in total since 1991, with wide-ranging and severe ecological and economic consequences. We go on to identify an interaction between decreasing water clarity and warming temperatures as the primary drivers of this trend. Declining clarity has gradually reduced eelgrass cover the past two decades, primarily in deeper beds where light is already limiting. In shallow beds, however, reduced visibility exacerbates the physiological stress of acute warming, leading to recent instances of decline approaching 80\\%. While degraded water quality has long been known to influence underwater grasses worldwide, we demonstrate a clear and rapidly emerging interaction with climate change. We highlight the urgent need to integrate a broader perspective into local water quality management, in the Chesapeake Bay and in the many other coastal systems facing similar stressors.},\n\tjournal = {Global Change Biology},\n\tauthor = {Lefcheck, Jonathan S. and Wilcox, David J. and Murphy, Rebecca R. and Marion, Scott R. and Orth, Robert J.},\n\tyear = {2017},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Interactions among global change stressors and their effects at large scales are often proposed, but seldom evaluated. This situation is primarily due to lack of comprehensive, sufficiently long-term, and spatially extensive datasets. Seagrasses, which provide nursery habitat, improve water quality, and constitute a globally important carbon sink, are among the most vulnerable habitats on the planet. Here, we unite 31 years of high-resolution aerial monitoring and water quality data to elucidate the patterns and drivers of eelgrass (Zostera marina) abundance in Chesapeake Bay, USA, one of the largest and most valuable estuaries in the world, with an unparalleled history of regulatory efforts. We show that eelgrass area has declined 29% in total since 1991, with wide-ranging and severe ecological and economic consequences. We go on to identify an interaction between decreasing water clarity and warming temperatures as the primary drivers of this trend. Declining clarity has gradually reduced eelgrass cover the past two decades, primarily in deeper beds where light is already limiting. In shallow beds, however, reduced visibility exacerbates the physiological stress of acute warming, leading to recent instances of decline approaching 80%. While degraded water quality has long been known to influence underwater grasses worldwide, we demonstrate a clear and rapidly emerging interaction with climate change. We highlight the urgent need to integrate a broader perspective into local water quality management, in the Chesapeake Bay and in the many other coastal systems facing similar stressors.\n
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\n \n\n \n \n \n \n \n Temporal variability in potential connectivity of Vallisneria americana in the Chesapeake Bay.\n \n \n \n\n\n \n Lloyd, M. W.; Widmeyer, P. A.; and Neel, M. C.\n\n\n \n\n\n\n Landscape Ecology. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{lloyd_temporal_2016,\n\ttitle = {Temporal variability in potential connectivity of {Vallisneria} americana in the {Chesapeake} {Bay}},\n\tdoi = {10.1007/s10980-016-0401-y},\n\tabstract = {Context: Submersed aquatic vegetation (SAV) performs water quality enhancing functions that are critical to the overall health of estuaries such as the Chesapeake Bay. However, eutrophication and sedimentation have decimated the Bay's SAV population to a fraction of its historical coverage. Understanding the spatial distribution of and connectedness among patches is important for assessing the dynamics and health of the remaining SAV population. Objectives: We seek to explore the distribution of SAV patches and patterns of potential connectivity in the Chesapeake Bay through time. Methods: We assess critical distances, from complete patch isolation to connection of all patches, in a merged composite coverage map that represents the sum of all probable Vallisneria americana containing patches between 1984 and 2010 and in coverage maps for individual years within that timeframe for which complete survey data are available. Results: We have three key findings: First, the amount of SAV coverage in any given year is much smaller than the total recently occupied acreage. Second, the vast majority of patches of SAV that are within the tolerances of V. americana are ephemeral, being observed in only 1 or 2 years out of 26 years. Third, this high patch turnover results in highly variable connectivity from year to year, dependent on dispersal distance and patch arrangement. Conclusions: Most of the connectivity thresholds are beyond reasonable dispersal distances for V. americana. If the high turnover in habitat occupancy is due to marginal water quality, relatively small improvements could greatly increase V. americana growth and persistence.},\n\tjournal = {Landscape Ecology},\n\tauthor = {Lloyd, Michael W. and Widmeyer, Paul A. and Neel, Maile C.},\n\tyear = {2016},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Context: Submersed aquatic vegetation (SAV) performs water quality enhancing functions that are critical to the overall health of estuaries such as the Chesapeake Bay. However, eutrophication and sedimentation have decimated the Bay's SAV population to a fraction of its historical coverage. Understanding the spatial distribution of and connectedness among patches is important for assessing the dynamics and health of the remaining SAV population. Objectives: We seek to explore the distribution of SAV patches and patterns of potential connectivity in the Chesapeake Bay through time. Methods: We assess critical distances, from complete patch isolation to connection of all patches, in a merged composite coverage map that represents the sum of all probable Vallisneria americana containing patches between 1984 and 2010 and in coverage maps for individual years within that timeframe for which complete survey data are available. Results: We have three key findings: First, the amount of SAV coverage in any given year is much smaller than the total recently occupied acreage. Second, the vast majority of patches of SAV that are within the tolerances of V. americana are ephemeral, being observed in only 1 or 2 years out of 26 years. Third, this high patch turnover results in highly variable connectivity from year to year, dependent on dispersal distance and patch arrangement. Conclusions: Most of the connectivity thresholds are beyond reasonable dispersal distances for V. americana. If the high turnover in habitat occupancy is due to marginal water quality, relatively small improvements could greatly increase V. americana growth and persistence.\n
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\n \n\n \n \n \n \n \n The Relationship Between Shoreline Armoring and Adjacent Submerged Aquatic Vegetation in Chesapeake Bay and Nearby Atlantic Coastal Bays.\n \n \n \n\n\n \n Patrick, C. J.; Weller, D. E.; and Ryder, M.\n\n\n \n\n\n\n Estuaries and Coasts. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{patrick_relationship_2016,\n\ttitle = {The {Relationship} {Between} {Shoreline} {Armoring} and {Adjacent} {Submerged} {Aquatic} {Vegetation} in {Chesapeake} {Bay} and {Nearby} {Atlantic} {Coastal} {Bays}},\n\tdoi = {10.1007/s12237-015-9970-2},\n\tabstract = {Shoreline armoring is an ancient and globally used engineering strategy to prevent shoreline erosion along marine, estuarine, and freshwater coastlines. Armoring alters the land water interface and has the potential to affect nearshore submerged aquatic vegetation (SAV) by changing nearshore hydrology, morphology, water clarity, and sediment composition. We quantified the relationships between the condition (bulkhead, riprap, or natural) of individual shoreline segments and three measures of directly adjacent SAV (the area of potential SAV habitat, the area occupied by SAV, and the proportion of potential habitat area that was occupied) in the Chesapeake Bay and nearby Atlantic coastal bays. Bulkhead had negative relationships with SAV in the polyhaline and mesohaline zones. Salinity and watershed land cover significantly modified the effect of shoreline armoring on nearshore SAV beds, and the effects of armoring were strongest in polyhaline subestuaries with forested watersheds. In high salinity systems, distance from shore modified the relationship between shoreline and SAV. The negative relationship between bulkhead and SAV was greater further off shore. By using individual shoreline segments as the study units, our analysis separated the effects of armoring and land cover, which were confounded in previous analyses that quantified average armoring and SAV abundance for much larger study units (subestuaries). Our findings suggest that redesigning or removing shoreline armoring structures may benefit nearshore SAV in some settings. Because armoring is ubiquitous, such information can inform efforts to reverse the global decline in SAV and the loss of the ecosystem services that SAV provides.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Patrick, Christopher J. and Weller, Donald E. and Ryder, Micah},\n\tyear = {2016},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Shoreline armoring is an ancient and globally used engineering strategy to prevent shoreline erosion along marine, estuarine, and freshwater coastlines. Armoring alters the land water interface and has the potential to affect nearshore submerged aquatic vegetation (SAV) by changing nearshore hydrology, morphology, water clarity, and sediment composition. We quantified the relationships between the condition (bulkhead, riprap, or natural) of individual shoreline segments and three measures of directly adjacent SAV (the area of potential SAV habitat, the area occupied by SAV, and the proportion of potential habitat area that was occupied) in the Chesapeake Bay and nearby Atlantic coastal bays. Bulkhead had negative relationships with SAV in the polyhaline and mesohaline zones. Salinity and watershed land cover significantly modified the effect of shoreline armoring on nearshore SAV beds, and the effects of armoring were strongest in polyhaline subestuaries with forested watersheds. In high salinity systems, distance from shore modified the relationship between shoreline and SAV. The negative relationship between bulkhead and SAV was greater further off shore. By using individual shoreline segments as the study units, our analysis separated the effects of armoring and land cover, which were confounded in previous analyses that quantified average armoring and SAV abundance for much larger study units (subestuaries). Our findings suggest that redesigning or removing shoreline armoring structures may benefit nearshore SAV in some settings. Because armoring is ubiquitous, such information can inform efforts to reverse the global decline in SAV and the loss of the ecosystem services that SAV provides.\n
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\n \n\n \n \n \n \n \n Mechanisms of Storm-Related Loss and Resilience in a Large Submersed Plant Bed.\n \n \n \n\n\n \n Gurbisz, C.; Kemp, W. M.; Sanford, L. P.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries and Coasts. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{gurbisz_mechanisms_2016,\n\ttitle = {Mechanisms of {Storm}-{Related} {Loss} and {Resilience} in a {Large} {Submersed} {Plant} {Bed}},\n\tdoi = {10.1007/s12237-016-0074-4},\n\tabstract = {There is a growing emphasis on preserving ecological resilience, or a system's capacity to absorb or recover quickly from perturbations, particularly in vulnerable coastal regions. However, the factors that affect resilience to a given disturbance are not always clear and may be system-specific. We analyzed and synthesized time series datasets to explore how extreme events impacted a large system of submersed aquatic vegetation (SAV) in upper Chesapeake Bay and to identify and understand associated mechanisms of resilience. We found that physical removal of plants around the edge of the bed by high flows during a major flood event as well as subsequent wind-driven resuspension of newly deposited sediment and attendant light-limiting conditions were detrimental to the SAV bed. Conversely, it appears that the bed attenuated high flows sufficiently to prevent plant erosion at its inner core. The bed also attenuated wind-driven wave amplitude during seasonal peaks in plant biomass, thereby decreasing sediment resuspension and increasing water clarity. In addition, clear water appeared to “spill over” into adjacent regions during ebb tide, improving the bed's capacity for renewal by creating more favorable growing conditions in areas where plant loss had occurred. These analyses demonstrate that positive feedback processes, whereby an SAV bed modifies its environment in ways that improve its own growth, likely serve as mechanisms of SAV resilience to flood events. Although this work focuses on a specific system, the synthetic approach used here can be applied to any system for which routine monitoring data are available.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Gurbisz, Cassie and Kemp, W. Michael and Sanford, Lawrence P. and Orth, Robert J.},\n\tyear = {2016},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n There is a growing emphasis on preserving ecological resilience, or a system's capacity to absorb or recover quickly from perturbations, particularly in vulnerable coastal regions. However, the factors that affect resilience to a given disturbance are not always clear and may be system-specific. We analyzed and synthesized time series datasets to explore how extreme events impacted a large system of submersed aquatic vegetation (SAV) in upper Chesapeake Bay and to identify and understand associated mechanisms of resilience. We found that physical removal of plants around the edge of the bed by high flows during a major flood event as well as subsequent wind-driven resuspension of newly deposited sediment and attendant light-limiting conditions were detrimental to the SAV bed. Conversely, it appears that the bed attenuated high flows sufficiently to prevent plant erosion at its inner core. The bed also attenuated wind-driven wave amplitude during seasonal peaks in plant biomass, thereby decreasing sediment resuspension and increasing water clarity. In addition, clear water appeared to “spill over” into adjacent regions during ebb tide, improving the bed's capacity for renewal by creating more favorable growing conditions in areas where plant loss had occurred. These analyses demonstrate that positive feedback processes, whereby an SAV bed modifies its environment in ways that improve its own growth, likely serve as mechanisms of SAV resilience to flood events. Although this work focuses on a specific system, the synthetic approach used here can be applied to any system for which routine monitoring data are available.\n
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\n \n\n \n \n \n \n \n Interannual variation in submerged aquatic vegetation and its relationship to water quality in subestuaries of Chesapeake Bay.\n \n \n \n\n\n \n Patrick, C. J.; and Weller, D. E.\n\n\n \n\n\n\n Marine Ecology Progress Series, 537: 121–135. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{patrick_interannual_2015,\n\ttitle = {Interannual variation in submerged aquatic vegetation and its relationship to water quality in subestuaries of {Chesapeake} {Bay}},\n\tvolume = {537},\n\tdoi = {10.3354/meps11412},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Patrick, Christopher J. and Weller, Donald E.},\n\tyear = {2015},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n\tpages = {121--135},\n}\n\n
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\n \n\n \n \n \n \n \n Roles of dispersal and predation in determining seedling recruitment patterns in a foundational marine angiosperm.\n \n \n \n\n\n \n Manley, S. R.; Orth, R. J.; and Ruiz-Montoya, L.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{manley_roles_2015,\n\ttitle = {Roles of dispersal and predation in determining seedling recruitment patterns in a foundational marine angiosperm},\n\tdoi = {10.3354/meps11363},\n\tabstract = {Seed dispersal and seed predation are 2 important processes in the early life history of plants. These mechanisms have been described extensively in terrestrial plants and have resulted in the creation of various models to describe seedling recruitment with increasing distance from the parent plant. However, it is unclear whether theoretical models derived from terrestrial studies apply to marine angiosperms. We performed observational and experimental tests of seed dispersal mechanisms in a marine environment to elucidate patterns of seed dispersal and predation in a foundational marine angiosperm, eelgrass Zostera marina. We also modeled seed dispersal and predation to explore how recruitment varies under different scenarios of predator activity and abundance. We found that seed densities were highest within and adjacent to vegetated areas. Predation pressure was low overall, and there was no significant difference in predation pressure between vegetated and unvegetated areas. Seedling densities were highly correlated with seed densities from the previous year, suggesting that seed predation had a limited impact on population recruitment. These results are consistent with the invariant survival model, which states that seed survivorship has no spatial trend. The theoretical scenarios we generated suggest that a low abundance of highly mobile, generalist predators may explain the patterns observed in our system. Therefore, seedling establishment rates are almost solely attributable and inversely proportional to distance from the parent plant. The results from this study have important implications for the recovery and restoration of these highly threatened coastal ecosystems.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Manley, Stephen R. and Orth, Robert J. and Ruiz-Montoya, Leonardo},\n\tyear = {2015},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Seed dispersal and seed predation are 2 important processes in the early life history of plants. These mechanisms have been described extensively in terrestrial plants and have resulted in the creation of various models to describe seedling recruitment with increasing distance from the parent plant. However, it is unclear whether theoretical models derived from terrestrial studies apply to marine angiosperms. We performed observational and experimental tests of seed dispersal mechanisms in a marine environment to elucidate patterns of seed dispersal and predation in a foundational marine angiosperm, eelgrass Zostera marina. We also modeled seed dispersal and predation to explore how recruitment varies under different scenarios of predator activity and abundance. We found that seed densities were highest within and adjacent to vegetated areas. Predation pressure was low overall, and there was no significant difference in predation pressure between vegetated and unvegetated areas. Seedling densities were highly correlated with seed densities from the previous year, suggesting that seed predation had a limited impact on population recruitment. These results are consistent with the invariant survival model, which states that seed survivorship has no spatial trend. The theoretical scenarios we generated suggest that a low abundance of highly mobile, generalist predators may explain the patterns observed in our system. Therefore, seedling establishment rates are almost solely attributable and inversely proportional to distance from the parent plant. The results from this study have important implications for the recovery and restoration of these highly threatened coastal ecosystems.\n
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\n \n\n \n \n \n \n \n Predicting effects of ocean warming, acidification, and water quality on Chesapeake region eelgrass.\n \n \n \n\n\n \n Zimmerman, R. C.; Hill, V. J.; and Gallegos, C. L.\n\n\n \n\n\n\n Limnology and Oceanography. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{zimmerman_predicting_2015,\n\ttitle = {Predicting effects of ocean warming, acidification, and water quality on {Chesapeake} region eelgrass},\n\tdoi = {10.1002/lno.10139},\n\tabstract = {Although environmental requirements of seagrasses have been studied for years, reliable metrics for predicting their response to current or future conditions remain elusive. Eelgrass (Zostera marina L.) populations of the Chesapeake region lie near the southern limit of their range in the Western North Atlantic, exposing them to increasing thermal stress as the climate warms. However, CO2 stimulated photosynthesis may offset some of the negative effects of temperature stress. The combined effects of temperature, CO2, and light availability controlled by water quality and epiphytes were explored using GrassLight, a bio-optical model that provided a predictive environment for evaluating the interaction of multiple stressors on eelgrass distribution and density across the submarine landscape. Model predictions were validated against in situ measures of spectral diffuse attenuation, eelgrass density, and distribution. The potential for photosynthesis stimulated by ocean acidification to mitigate the effects of high temperature on eelgrass populations growing near the southern limit of their distribution was explored. The model accurately reproduced the submarine light environment from measured water quality parameters, and predicted their impacts on eelgrass distribution. It also reproduced the negative effects of warm summer temperatures on eelgrass distributions, and demonstrated that CO2 increases projected for the next century should stimulate photosynthesis sufficiently to offset the negative effects of thermal stress on eelgrass growing in the Chesapeake region, even in the presence of epiphytes. Thus, improved water quality should facilitate the survival of eelgrass populations in Chesapeake region, even in the face of a warming climate.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Zimmerman, Richard C. and Hill, Victoria J. and Gallegos, Charles L.},\n\tyear = {2015},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Although environmental requirements of seagrasses have been studied for years, reliable metrics for predicting their response to current or future conditions remain elusive. Eelgrass (Zostera marina L.) populations of the Chesapeake region lie near the southern limit of their range in the Western North Atlantic, exposing them to increasing thermal stress as the climate warms. However, CO2 stimulated photosynthesis may offset some of the negative effects of temperature stress. The combined effects of temperature, CO2, and light availability controlled by water quality and epiphytes were explored using GrassLight, a bio-optical model that provided a predictive environment for evaluating the interaction of multiple stressors on eelgrass distribution and density across the submarine landscape. Model predictions were validated against in situ measures of spectral diffuse attenuation, eelgrass density, and distribution. The potential for photosynthesis stimulated by ocean acidification to mitigate the effects of high temperature on eelgrass populations growing near the southern limit of their distribution was explored. The model accurately reproduced the submarine light environment from measured water quality parameters, and predicted their impacts on eelgrass distribution. It also reproduced the negative effects of warm summer temperatures on eelgrass distributions, and demonstrated that CO2 increases projected for the next century should stimulate photosynthesis sufficiently to offset the negative effects of thermal stress on eelgrass growing in the Chesapeake region, even in the presence of epiphytes. Thus, improved water quality should facilitate the survival of eelgrass populations in Chesapeake region, even in the face of a warming climate.\n
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\n \n\n \n \n \n \n \n Modeling loss and recovery of Zostera marina beds in the Chesapeake Bay: The role of seedlings and seed-bank viability.\n \n \n \n\n\n \n Jarvis, J. C.; Brush, M. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{jarvis_modeling_2014,\n\ttitle = {Modeling loss and recovery of {Zostera} marina beds in the {Chesapeake} {Bay}: {The} role of seedlings and seed-bank viability},\n\tdoi = {10.1016/j.aquabot.2013.10.010},\n\tabstract = {Loss and recovery processes following a documented large scale decline in Zostera marina beds in the York River, Virginia in 2005 were modeled by coupling production and sexual reproduction models. The reproduction model included formulations for reproductive shoot production, seed production, seed-bank density, seed viability, and seed germination. After the model was calibrated and validated using in situ water quality and plant performance measurements from two different sites, model scenarios were run for three years (1 year pre-decline, 2 years post-decline) to quantify the effects of (1) the presence or absence of sexual reproduction, (2) increases in water temperatures from ambient to ambient +5. °C in 1. °C increments, and (3) the potential interactive effects of light and temperature conditions on bed maintenance and re-establishment. Model projections of Z. marina production following the decline corresponded to in situ measurements of recovery only when sexual reproduction was added. However, a 1. °C increase in temperature resulted in a complete loss of biomass after two consecutive years of temperature stress following the depletion of the viable sediment seed bank. Interactions between light and temperature stress resulted in overall lower production and resilience to declines under lower light conditions due to corresponding decreases in photosynthetic rates and increases in respiration. Model results highlight (1) the need to incorporate sexual reproduction into Z. marina ecosystem models, (2) the projected sensitivity of established beds to consecutive years of stress, and (3) the negative effects of multiple stressors on Z. marina resilience and recovery. © 2013 Elsevier B.V.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Jarvis, Jessie C. and Brush, Mark J. and Moore, Kenneth A.},\n\tyear = {2014},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Loss and recovery processes following a documented large scale decline in Zostera marina beds in the York River, Virginia in 2005 were modeled by coupling production and sexual reproduction models. The reproduction model included formulations for reproductive shoot production, seed production, seed-bank density, seed viability, and seed germination. After the model was calibrated and validated using in situ water quality and plant performance measurements from two different sites, model scenarios were run for three years (1 year pre-decline, 2 years post-decline) to quantify the effects of (1) the presence or absence of sexual reproduction, (2) increases in water temperatures from ambient to ambient +5. °C in 1. °C increments, and (3) the potential interactive effects of light and temperature conditions on bed maintenance and re-establishment. Model projections of Z. marina production following the decline corresponded to in situ measurements of recovery only when sexual reproduction was added. However, a 1. °C increase in temperature resulted in a complete loss of biomass after two consecutive years of temperature stress following the depletion of the viable sediment seed bank. Interactions between light and temperature stress resulted in overall lower production and resilience to declines under lower light conditions due to corresponding decreases in photosynthetic rates and increases in respiration. Model results highlight (1) the need to incorporate sexual reproduction into Z. marina ecosystem models, (2) the projected sensitivity of established beds to consecutive years of stress, and (3) the negative effects of multiple stressors on Z. marina resilience and recovery. © 2013 Elsevier B.V.\n
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\n \n\n \n \n \n \n \n Unexpected resurgence of a large submersed plant bed in Chesapeake Bay: Analysis of time series data.\n \n \n \n\n\n \n Gurbisz, C.; and Michael Kemp, W.\n\n\n \n\n\n\n Limnology and Oceanography. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{gurbisz_unexpected_2014,\n\ttitle = {Unexpected resurgence of a large submersed plant bed in {Chesapeake} {Bay}: {Analysis} of time series data},\n\tdoi = {10.4319/lo.2014.59.2.0482},\n\tabstract = {An historically large ({\\textbackslash}textgreater 50 km2) submersed plant bed in upper Chesapeake Bay virtually disappeared in 1972, following Tropical Storm Agnes. The bed experienced little regrowth until the early 2000s, when plant abundance rapidly increased. Here, we analyze a suite of recent (1984-2010) and historical (1958-1983) time series datasets to assess alternative explanations for the submersed plant resurgence. Change-point analysis showed that spring nitrogen (N) loading increased from 1945 to 1988 and decreased from 1988 to 2010. Analysis of variance on recent time series showed a significant difference in submersed aquatic vegetation (SAV) abundance percent change during wet years (-7 ± 11\\%) and dry years (53 ± 20\\%), indicating that floods and droughts likely contributed to SAV loss and growth, respectively. In the historic dataset, however, increasingly poor water quality led to SAV loss despite an extended drought period, indicating that underlying water quality trends were also important in driving change in SAV abundance. Several water quality variables, including N concentration and turbidity, were lower inside the SAV bed than outside the SAV bed, implying the presence of feedback processes whereby the bed improves its own growing conditions by enhancing biophysical processes such as sediment deposition and nutrient cycling. Together, these analyses suggest that stochastic extremes in river discharge and long-term water quality trends synergistically facilitated sudden shifts in SAV abundance and that feedback processes likely reinforced the state of the bed before and after the shifts. Management efforts should consider these dynamic interactions and minimize chronic underlying stressors, which are often anthropogenic in origin. © 2014, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Gurbisz, Cassie and Michael Kemp, W.},\n\tyear = {2014},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n An historically large (\\textgreater 50 km2) submersed plant bed in upper Chesapeake Bay virtually disappeared in 1972, following Tropical Storm Agnes. The bed experienced little regrowth until the early 2000s, when plant abundance rapidly increased. Here, we analyze a suite of recent (1984-2010) and historical (1958-1983) time series datasets to assess alternative explanations for the submersed plant resurgence. Change-point analysis showed that spring nitrogen (N) loading increased from 1945 to 1988 and decreased from 1988 to 2010. Analysis of variance on recent time series showed a significant difference in submersed aquatic vegetation (SAV) abundance percent change during wet years (-7 ± 11%) and dry years (53 ± 20%), indicating that floods and droughts likely contributed to SAV loss and growth, respectively. In the historic dataset, however, increasingly poor water quality led to SAV loss despite an extended drought period, indicating that underlying water quality trends were also important in driving change in SAV abundance. Several water quality variables, including N concentration and turbidity, were lower inside the SAV bed than outside the SAV bed, implying the presence of feedback processes whereby the bed improves its own growing conditions by enhancing biophysical processes such as sediment deposition and nutrient cycling. Together, these analyses suggest that stochastic extremes in river discharge and long-term water quality trends synergistically facilitated sudden shifts in SAV abundance and that feedback processes likely reinforced the state of the bed before and after the shifts. Management efforts should consider these dynamic interactions and minimize chronic underlying stressors, which are often anthropogenic in origin. © 2014, by the Association for the Sciences of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Patterns of seagrass community response to local shoreline development.\n \n \n \n\n\n \n Blake, R. E.; Duffy, J. E.; and Richardson, J. P.\n\n\n \n\n\n\n Estuaries and Coasts. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{blake_patterns_2014,\n\ttitle = {Patterns of seagrass community response to local shoreline development},\n\tdoi = {10.1007/s12237-014-9784-7},\n\tabstract = {Three quarters of the global human population will live in coastal areas in the coming decades and will continue to develop these areas as population density increases. Anthropogenic stressors from this coastal development may lead to fragmented habitats, altered food webs, changes in sediment characteristics, and loss of near-shore vegetated habitats. Seagrass systems are important vegetated estuarine habitats that are vulnerable to anthropogenic stressors, but provide valuable ecosystem functions. Key to maintaining these habitats that filter water, stabilize sediments, and provide refuge to juvenile animals is an understanding of the impacts of local coastal development. To assess development impacts in seagrass communities, we surveyed 20 seagrass beds in lower Chesapeake Bay, VA. We sampled primary producers, consumers, water quality, and sediment characteristics in seagrass beds, and characterized development along the adjacent shoreline using land cover data. Overall, we could not detect effects of local coastal development on these seagrass communities. Seagrass biomass varied only between sites, and was positively correlated with sediment organic matter. Epiphytic algal biomass and epibiont (epifauna and epiphyte) community composition varied between western and eastern regions of the bay. But, neither eelgrass (Zostera marina) leaf nitrogen (a proxy for integrated nitrogen loading), crustacean grazer biomass, epifaunal predator abundance, nor fish and crab abundance differed significantly among sites or regions. Overall, factors operating on different scales appear to drive primary producers, seagrass-associated faunal communities, and sediment properties in these important submerged vegetated habitats in lower Chesapeake Bay.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Blake, Rachael E. and Duffy, J. Emmett and Richardson, J. Paul},\n\tyear = {2014},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Three quarters of the global human population will live in coastal areas in the coming decades and will continue to develop these areas as population density increases. Anthropogenic stressors from this coastal development may lead to fragmented habitats, altered food webs, changes in sediment characteristics, and loss of near-shore vegetated habitats. Seagrass systems are important vegetated estuarine habitats that are vulnerable to anthropogenic stressors, but provide valuable ecosystem functions. Key to maintaining these habitats that filter water, stabilize sediments, and provide refuge to juvenile animals is an understanding of the impacts of local coastal development. To assess development impacts in seagrass communities, we surveyed 20 seagrass beds in lower Chesapeake Bay, VA. We sampled primary producers, consumers, water quality, and sediment characteristics in seagrass beds, and characterized development along the adjacent shoreline using land cover data. Overall, we could not detect effects of local coastal development on these seagrass communities. Seagrass biomass varied only between sites, and was positively correlated with sediment organic matter. Epiphytic algal biomass and epibiont (epifauna and epiphyte) community composition varied between western and eastern regions of the bay. But, neither eelgrass (Zostera marina) leaf nitrogen (a proxy for integrated nitrogen loading), crustacean grazer biomass, epifaunal predator abundance, nor fish and crab abundance differed significantly among sites or regions. Overall, factors operating on different scales appear to drive primary producers, seagrass-associated faunal communities, and sediment properties in these important submerged vegetated habitats in lower Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Impacts of Varying Estuarine Temperature and Light Conditions on Zostera marina (Eelgrass) and its Interactions With Ruppia maritima (Widgeongrass).\n \n \n \n\n\n \n Moore, K. A.; Shields, E. C.; and Parrish, D. B.\n\n\n \n\n\n\n Estuaries and Coasts. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_impacts_2014,\n\ttitle = {Impacts of {Varying} {Estuarine} {Temperature} and {Light} {Conditions} on {Zostera} marina ({Eelgrass}) and its {Interactions} {With} {Ruppia} maritima ({Widgeongrass})},\n\tdoi = {10.1007/s12237-013-9667-3},\n\tabstract = {Seagrass populations have been declining globally, with changes attributed to anthropogenic stresses and, more recently, negative effects of global climate change. We examined the distribution of Zostera marina (eelgrass) dominated beds in the York River, Chesapeake Bay, VA over an 8-year time period. Using a temperature-dependent light model, declines in upriver areas were associated with higher light attenuation, resulting in lower light availability relative to compensating light requirements of Z. marina compared with downriver areas. An inverse relationship was observed between SAV growth and temperature with a change between net bed cover increases and decreases for the period of 2004-2011 observed at approximately 23 °C. Z. marina-dominated beds in the lower river have been recovering from a die-off event in 2005 and experienced another near complete decline in 2010, losing an average of 97 \\% of coverage of Z. marina from June to October. These 2010 declines were attributed to an early summer heat event in which daily mean water temperatures increased from 25 to 30 °C over a 2-week time period, considerably higher than previous years when complete die-offs were not observed. Z. marina recovery from this event was minimal, while Ruppia maritima (widgeongrass) expanded its abundance. Water temperatures are projected to continue to increase in the Chesapeake Bay and elsewhere. These results suggest that short-term exposures to rapidly increasing temperatures by 4-5 °C above normal during summer months can result in widespread diebacks that may lead to Z. marina extirpation from historically vegetated areas, with the potential replacement by other species. © 2013 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Moore, Kenneth A. and Shields, Erin C. and Parrish, David B.},\n\tyear = {2014},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Seagrass populations have been declining globally, with changes attributed to anthropogenic stresses and, more recently, negative effects of global climate change. We examined the distribution of Zostera marina (eelgrass) dominated beds in the York River, Chesapeake Bay, VA over an 8-year time period. Using a temperature-dependent light model, declines in upriver areas were associated with higher light attenuation, resulting in lower light availability relative to compensating light requirements of Z. marina compared with downriver areas. An inverse relationship was observed between SAV growth and temperature with a change between net bed cover increases and decreases for the period of 2004-2011 observed at approximately 23 °C. Z. marina-dominated beds in the lower river have been recovering from a die-off event in 2005 and experienced another near complete decline in 2010, losing an average of 97 % of coverage of Z. marina from June to October. These 2010 declines were attributed to an early summer heat event in which daily mean water temperatures increased from 25 to 30 °C over a 2-week time period, considerably higher than previous years when complete die-offs were not observed. Z. marina recovery from this event was minimal, while Ruppia maritima (widgeongrass) expanded its abundance. Water temperatures are projected to continue to increase in the Chesapeake Bay and elsewhere. These results suggest that short-term exposures to rapidly increasing temperatures by 4-5 °C above normal during summer months can result in widespread diebacks that may lead to Z. marina extirpation from historically vegetated areas, with the potential replacement by other species. © 2013 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Broad-scale association between seagrass cover and juvenile blue crab density in Chesapeake Bay.\n \n \n \n\n\n \n Ralph, G. M.; Seitz, R. D.; Orth, R. J.; Knick, K. E.; and Lipcius, R. N.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{ralph_broad-scale_2013,\n\ttitle = {Broad-scale association between seagrass cover and juvenile blue crab density in {Chesapeake} {Bay}},\n\tdoi = {10.3354/meps10417},\n\tabstract = {Although numerous small-scale laboratory, mesocosm, and field experiments have demonstrated that abundance, survival, and growth of juvenile fish and invertebrates are higher in vegetated than in unvegetated habitats, the effect of habitat quality (i.e. habitat complexity) within vegetated habitats has not been documented at a broad spatial scale. We examined the relationship between percent cover in seagrass beds (eelgrass Zostera marina, widgeon grass Ruppia maritima, and associated macroalgae) and juvenile blue crab Callinectes sapidus density at a broad spatial scale. We quantified the functional relationship between juvenile density and percent cover of vegetation by sampling in Chesapeake Bay (USA) seagrass beds utilized by juvenile blue crabs in the fall of 2007 and 2008, following peak postlarval blue crab recruitment. Based on Akaike's information criterion model comparisons, the most plausible model included both percent cover of vegetation and region of Chesapeake Bay. Juvenile crab density was a positive exponential function of percent cover of vegetation, and was augmented by 14 to 30\\%, depending on year, for every 10\\% increase in cover. Density was approximately 2 times higher on the western shore of Chesapeake Bay than on the eastern shore. Seagrass bed area, presence or absence of algae, and distance to the mouth of the bay did not significantly influence density. An expected threshold (i.e. sigmoid) response of juvenile density to percent cover of vegetation was not evident, probably because this study was undertaken when recruitment was low, so habitats may not have been at carrying capacity. This study is the first to document the functional relationship between habitat quality and juvenile density at a broad spatial scale for a marine fish or invertebrate, and suggests that the quality of seagrass habitat influences population dynamics. © Inter-Research 2013.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Ralph, Gina M. and Seitz, Rochelle D. and Orth, Robert J. and Knick, Kathleen E. and Lipcius, Romuald N.},\n\tyear = {2013},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Although numerous small-scale laboratory, mesocosm, and field experiments have demonstrated that abundance, survival, and growth of juvenile fish and invertebrates are higher in vegetated than in unvegetated habitats, the effect of habitat quality (i.e. habitat complexity) within vegetated habitats has not been documented at a broad spatial scale. We examined the relationship between percent cover in seagrass beds (eelgrass Zostera marina, widgeon grass Ruppia maritima, and associated macroalgae) and juvenile blue crab Callinectes sapidus density at a broad spatial scale. We quantified the functional relationship between juvenile density and percent cover of vegetation by sampling in Chesapeake Bay (USA) seagrass beds utilized by juvenile blue crabs in the fall of 2007 and 2008, following peak postlarval blue crab recruitment. Based on Akaike's information criterion model comparisons, the most plausible model included both percent cover of vegetation and region of Chesapeake Bay. Juvenile crab density was a positive exponential function of percent cover of vegetation, and was augmented by 14 to 30%, depending on year, for every 10% increase in cover. Density was approximately 2 times higher on the western shore of Chesapeake Bay than on the eastern shore. Seagrass bed area, presence or absence of algae, and distance to the mouth of the bay did not significantly influence density. An expected threshold (i.e. sigmoid) response of juvenile density to percent cover of vegetation was not evident, probably because this study was undertaken when recruitment was low, so habitats may not have been at carrying capacity. This study is the first to document the functional relationship between habitat quality and juvenile density at a broad spatial scale for a marine fish or invertebrate, and suggests that the quality of seagrass habitat influences population dynamics. © Inter-Research 2013.\n
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\n \n\n \n \n \n \n \n Seasonal Growth and Senescence of a Zostera marina Seagrass Meadow Alters Wave-Dominated Flow and Sediment Suspension Within a Coastal Bay.\n \n \n \n\n\n \n Hansen, J. C.; and Reidenbach, M. A.\n\n\n \n\n\n\n Estuaries and Coasts. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{hansen_seasonal_2013,\n\ttitle = {Seasonal {Growth} and {Senescence} of a {Zostera} marina {Seagrass} {Meadow} {Alters} {Wave}-{Dominated} {Flow} and {Sediment} {Suspension} {Within} a {Coastal} {Bay}},\n\tdoi = {10.1007/s12237-013-9620-5},\n\tabstract = {Tidally driven flows, waves, and suspended sediment concentrations were monitored seasonally within a Zostera marina seagrass (eelgrass) meadow located in a shallow (1-2 m depth) coastal bay. Eelgrass meadows were found to reduce velocities approximately 60 \\% in the summer and 40 \\% in the winter compared to an adjacent unvegetated site. Additionally, the seagrass meadow served to dampen wave heights for all seasons except during winter when seagrass meadow development was at a minimum. Although wave heights were attenuated across the meadow, orbital motions caused by waves were able to effectively penetrate through the canopy, inducing wave-enhanced bottom shear stress (τb). Within the seagrass meadow, τb was greater than the critical stress threshold (=0.04 Pa) necessary to induce sediment suspension 80-85 \\% of the sampling period in the winter and spring, but only 55 \\% of the time in the summer. At the unvegetated site, τb was above the critical threshold greater than 90 \\% of the time across all seasons. During low seagrass coverage in the winter, near-bed turbulence levels were enhanced, likely caused by stem-wake interaction with the sparse canopy. Reduction in τb within the seagrass meadow during the summer correlated to a 60 \\% reduction in suspended sediment concentrations but in winter, suspended sediment was enhanced compared to the unvegetated site. With minimal seagrass coverage, τb and wave statistics were similar to unvegetated regions; however, during high seagrass coverage, sediment stabilization increased light availability for photosynthesis and created a positive feedback for seagrass growth. © 2013 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Hansen, Jennifer C.R. and Reidenbach, Matthew A.},\n\tyear = {2013},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Tidally driven flows, waves, and suspended sediment concentrations were monitored seasonally within a Zostera marina seagrass (eelgrass) meadow located in a shallow (1-2 m depth) coastal bay. Eelgrass meadows were found to reduce velocities approximately 60 % in the summer and 40 % in the winter compared to an adjacent unvegetated site. Additionally, the seagrass meadow served to dampen wave heights for all seasons except during winter when seagrass meadow development was at a minimum. Although wave heights were attenuated across the meadow, orbital motions caused by waves were able to effectively penetrate through the canopy, inducing wave-enhanced bottom shear stress (τb). Within the seagrass meadow, τb was greater than the critical stress threshold (=0.04 Pa) necessary to induce sediment suspension 80-85 % of the sampling period in the winter and spring, but only 55 % of the time in the summer. At the unvegetated site, τb was above the critical threshold greater than 90 % of the time across all seasons. During low seagrass coverage in the winter, near-bed turbulence levels were enhanced, likely caused by stem-wake interaction with the sparse canopy. Reduction in τb within the seagrass meadow during the summer correlated to a 60 % reduction in suspended sediment concentrations but in winter, suspended sediment was enhanced compared to the unvegetated site. With minimal seagrass coverage, τb and wave statistics were similar to unvegetated regions; however, during high seagrass coverage, sediment stabilization increased light availability for photosynthesis and created a positive feedback for seagrass growth. © 2013 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Influences of Salinity and Light Availability on Abundance and Distribution of Tidal Freshwater and Oligohaline Submersed Aquatic Vegetation.\n \n \n \n\n\n \n Shields, E. C.; Moore, K. A.; and Parrish, D. B.\n\n\n \n\n\n\n Estuaries and Coasts, 35(2): 515–526. 2012.\n Number: 2\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{shields_influences_2012,\n\ttitle = {Influences of {Salinity} and {Light} {Availability} on {Abundance} and {Distribution} of {Tidal} {Freshwater} and {Oligohaline} {Submersed} {Aquatic} {Vegetation}},\n\tvolume = {35},\n\tdoi = {10.1007/s12237-011-9460-0},\n\tabstract = {Submersed aquatic vegetation (SAV) communities have undergone declines worldwide, exposing them to invasions from non-native species. Over the past decade, the invasive species Hydrilla verticillata has been documented in several tributaries of the lower Chesapeake Bay, Virginia. We used annual aerial mapping surveys from 1998 to 2007, integrated with spatial analyses of water quality data, to analyze the patterns and rates of change of a H. verticillata-dominated SAV community and relate them to varying salinity and light conditions. Periods of declining SAV coverage corresponded to periods where salinities exceeded 7 and early growing season (April to May) Secchi depths were {\\textbackslash}textless0.4 m. Increases were driven by the expansion of H. verticillata along with several other species into the upper estuary, where some areas experienced an 80\\% increase in cover. Field investigations revealed H. verticillata dominance to be limited to the upper estuary where total suspended solid concentrations during the early growing season were {\\textbackslash}textless15 mg l−1 and salinity remained {\\textbackslash}textless3. The effect of poor early growing season water clarity on annual SAV growth highlights the importance of water quality during this critical life stage. Periods of low clarity combined with periodic salinity intrusions may limit the dominance of H. verticillata in these types of estuarine systems. This study shows the importance of the use of these types of biologically relevant episodic events to supplement seasonal habitat requirements and also provides evidence for the potential important role of invasive species in SAV community recovery.},\n\tnumber = {2},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Shields, Erin C. and Moore, Kenneth A. and Parrish, David B.},\n\tyear = {2012},\n\tnote = {Number: 2},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n\tpages = {515--526},\n}\n\n
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\n Submersed aquatic vegetation (SAV) communities have undergone declines worldwide, exposing them to invasions from non-native species. Over the past decade, the invasive species Hydrilla verticillata has been documented in several tributaries of the lower Chesapeake Bay, Virginia. We used annual aerial mapping surveys from 1998 to 2007, integrated with spatial analyses of water quality data, to analyze the patterns and rates of change of a H. verticillata-dominated SAV community and relate them to varying salinity and light conditions. Periods of declining SAV coverage corresponded to periods where salinities exceeded 7 and early growing season (April to May) Secchi depths were \\textless0.4 m. Increases were driven by the expansion of H. verticillata along with several other species into the upper estuary, where some areas experienced an 80% increase in cover. Field investigations revealed H. verticillata dominance to be limited to the upper estuary where total suspended solid concentrations during the early growing season were \\textless15 mg l−1 and salinity remained \\textless3. The effect of poor early growing season water clarity on annual SAV growth highlights the importance of water quality during this critical life stage. Periods of low clarity combined with periodic salinity intrusions may limit the dominance of H. verticillata in these types of estuarine systems. This study shows the importance of the use of these types of biologically relevant episodic events to supplement seasonal habitat requirements and also provides evidence for the potential important role of invasive species in SAV community recovery.\n
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\n \n\n \n \n \n \n \n Sediment Accumulation Rates and Submersed Aquatic Vegetation (SAV) Distributions in the Mesohaline Chesapeake Bay, USA.\n \n \n \n\n\n \n Palinkas, C. M.; and Koch, E. W.\n\n\n \n\n\n\n Estuaries and Coasts. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{palinkas_sediment_2012,\n\ttitle = {Sediment {Accumulation} {Rates} and {Submersed} {Aquatic} {Vegetation} ({SAV}) {Distributions} in the {Mesohaline} {Chesapeake} {Bay}, {USA}},\n\tdoi = {10.1007/s12237-012-9542-7},\n\tabstract = {This study assesses spatial and temporal sedimentological trends in four mesohaline Chesapeake Bay submersed aquatic vegetation (SAV) habitats, two with persistent SAV beds and two with ephemeral SAV beds, to determine their relationship to current and historical sediment characteristics-grain size, organic content, and accumulation rates. In general, grain size is similar among all sites, and subsurface sediment differs from surficial sediment only at one site where a thin surficial sand layer (∼2-3 cm) is present. This thin sand layer is not completely preserved in the longer-term sedimentary record even though it is critical to determining whether the sediment is suitable for SAV. Evidence for nearshore fining, similar to that observed in the deeper waters of the Bay, is present at the site where the shoreline has been hardened suggesting that locations with hardened shorelines limit exchange of coarser (sandy) material between the shore and nearshore environments. Whether the fining trend will continue to a point at which the sediment will become unsuitable for SAV in the future or whether some new type of equilibrium will be reached cannot be addressed with our data. Instead, our data suggest that SAV presence/absence is related to changes in sedimentary characteristics-persistent beds have relatively steady sediment composition, while ephemeral beds have finer sediments due to reduced sand input. Additionally, sediment accumulation rates in the persistent beds are ∼9 mm/year, whereas rates in the ephemeral beds are ∼3 mm/year. Thus, the ephemeral sites highlight two potential sedimentary controls on SAV distribution: the presence of a sufficiently thick surficial sand layer as previously postulated by Wicks (2005) and accumulation rates high enough to bury seeds prior to germination and/or keep up with sea-level rise. © 2012 Coastal and Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Palinkas, Cindy M. and Koch, Evamaria W.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n This study assesses spatial and temporal sedimentological trends in four mesohaline Chesapeake Bay submersed aquatic vegetation (SAV) habitats, two with persistent SAV beds and two with ephemeral SAV beds, to determine their relationship to current and historical sediment characteristics-grain size, organic content, and accumulation rates. In general, grain size is similar among all sites, and subsurface sediment differs from surficial sediment only at one site where a thin surficial sand layer (∼2-3 cm) is present. This thin sand layer is not completely preserved in the longer-term sedimentary record even though it is critical to determining whether the sediment is suitable for SAV. Evidence for nearshore fining, similar to that observed in the deeper waters of the Bay, is present at the site where the shoreline has been hardened suggesting that locations with hardened shorelines limit exchange of coarser (sandy) material between the shore and nearshore environments. Whether the fining trend will continue to a point at which the sediment will become unsuitable for SAV in the future or whether some new type of equilibrium will be reached cannot be addressed with our data. Instead, our data suggest that SAV presence/absence is related to changes in sedimentary characteristics-persistent beds have relatively steady sediment composition, while ephemeral beds have finer sediments due to reduced sand input. Additionally, sediment accumulation rates in the persistent beds are ∼9 mm/year, whereas rates in the ephemeral beds are ∼3 mm/year. Thus, the ephemeral sites highlight two potential sedimentary controls on SAV distribution: the presence of a sufficiently thick surficial sand layer as previously postulated by Wicks (2005) and accumulation rates high enough to bury seeds prior to germination and/or keep up with sea-level rise. © 2012 Coastal and Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Eelgrass survival in two contrasting systems: Role of turbidity and summer water temperatures.\n \n \n \n\n\n \n Moore, K. A.; Shields, E. C.; Parrish, D. B.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{moore_eelgrass_2012,\n\ttitle = {Eelgrass survival in two contrasting systems: {Role} of turbidity and summer water temperatures},\n\tdoi = {10.3354/meps09578},\n\tabstract = {Eelgrass Zostera marina L. distribution patterns in the mid-Atlantic region of the USA have shown complex changes, with recovery from losses in the 1930s varying between the coastal lagoons and Chesapeake Bay. Restoration efforts in the coastal bays of Virginia introduced Z. marina back to this system, and expansion since 2005 has averaged 66\\% yr -1. In contrast, Chesapeake Bay has experienced 2\\% expansion and has undergone 2 significant die-off events, in 2005 and 2010. We used a temperature-dependent light model to show that from 2005 to 2010 during daylight periods in the summer, coastal bay beds received at least 100\\% of their light requirements 24\\% of the time, while beds in the lower Chesapeake Bay only met this 6\\% of the time. Summer light attenuation (K d) and temperatures from continuous monitoring at 2 additional Chesapeake Bay sites in 2010 suggest that the greater tidal range and proximity of the coastal bays to cooler ocean waters may ameliorate influences of exposure to stressful high water temperature conditions compared to Chesapeake Bay. A temperature difference of 1°C combined with a K d difference of 0.5 m -1 at 1 m depth results in a 30\\% difference in available light as a proportion of community light requirements. These differences are critical between survival and decline in these perennial populations growing near the southern limits of their range. Without an increase in available light, Chesapeake Bay populations may be severely reduced or eliminated, while coastal bay populations, because of their proximity to cooler Atlantic waters, may become the refuge populations for this region. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Moore, Kenneth A. and Shields, Erin C. and Parrish, David B. and Orth, Robert J.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Eelgrass Zostera marina L. distribution patterns in the mid-Atlantic region of the USA have shown complex changes, with recovery from losses in the 1930s varying between the coastal lagoons and Chesapeake Bay. Restoration efforts in the coastal bays of Virginia introduced Z. marina back to this system, and expansion since 2005 has averaged 66% yr -1. In contrast, Chesapeake Bay has experienced 2% expansion and has undergone 2 significant die-off events, in 2005 and 2010. We used a temperature-dependent light model to show that from 2005 to 2010 during daylight periods in the summer, coastal bay beds received at least 100% of their light requirements 24% of the time, while beds in the lower Chesapeake Bay only met this 6% of the time. Summer light attenuation (K d) and temperatures from continuous monitoring at 2 additional Chesapeake Bay sites in 2010 suggest that the greater tidal range and proximity of the coastal bays to cooler ocean waters may ameliorate influences of exposure to stressful high water temperature conditions compared to Chesapeake Bay. A temperature difference of 1°C combined with a K d difference of 0.5 m -1 at 1 m depth results in a 30% difference in available light as a proportion of community light requirements. These differences are critical between survival and decline in these perennial populations growing near the southern limits of their range. Without an increase in available light, Chesapeake Bay populations may be severely reduced or eliminated, while coastal bay populations, because of their proximity to cooler Atlantic waters, may become the refuge populations for this region. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Wave and tidally driven flows in eelgrass beds and their effect on sediment suspension.\n \n \n \n\n\n \n Hansen, J. C.; and Reidenbach, M. A.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{hansen_wave_2012,\n\ttitle = {Wave and tidally driven flows in eelgrass beds and their effect on sediment suspension},\n\tdoi = {10.3354/meps09225},\n\tabstract = {Seagrass beds alter their hydrodynamic environment by inducing drag on the flow, thereby attenuating wave energy and near-bottom currents. This alters the turbulent structure and shear stresses within and around the seagrass bed that are responsible for the suspension and deposition of sediment. To quantify these interactions, velocity, pressure, and sediment measurements were obtained across a density gradient of an eelgrass Zostera marina bed within a shallow coastal bay (1 to 2 m depth). Eelgrass beds were found to reduce near-bottom mean velocities by 70 to 90\\%, while wave heights were reduced 45 to 70\\% compared to an adjacent unvegetated region. Wave orbital velocities within the eelgrass bed were reduced by 20\\% compared to flow above the bed, primarily acting as a low-pass filter by removing high-frequency wave motion. However, relatively little reduction in wave energy occurred at lower wave frequencies, suggesting that longer period waves were able to effectively penetrate the seagrass meadow. Average bottom shear stresses (τ b) at the unvegetated region were τ b = 0.17 ± 0.08 N m -2, significantly larger than the critical stress threshold necessary for sediment entrainment of 0.04 N m -2. Within the eelgrass bed, τ b = 0.03 ± 0.02 N m -2 and stresses were below the critical stress threshold during 80\\% of the time period of measurement. Expansion of eelgrass within the coastal bay has thus altered the dynamics of the seafloor from an erosional environment to one that promotes de - position of suspended sediment, enhancing light penetration throughout the water column and creating a positive feedback for eelgrass growth. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Hansen, Jennifer C.R. and Reidenbach, Matthew A.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Seagrass beds alter their hydrodynamic environment by inducing drag on the flow, thereby attenuating wave energy and near-bottom currents. This alters the turbulent structure and shear stresses within and around the seagrass bed that are responsible for the suspension and deposition of sediment. To quantify these interactions, velocity, pressure, and sediment measurements were obtained across a density gradient of an eelgrass Zostera marina bed within a shallow coastal bay (1 to 2 m depth). Eelgrass beds were found to reduce near-bottom mean velocities by 70 to 90%, while wave heights were reduced 45 to 70% compared to an adjacent unvegetated region. Wave orbital velocities within the eelgrass bed were reduced by 20% compared to flow above the bed, primarily acting as a low-pass filter by removing high-frequency wave motion. However, relatively little reduction in wave energy occurred at lower wave frequencies, suggesting that longer period waves were able to effectively penetrate the seagrass meadow. Average bottom shear stresses (τ b) at the unvegetated region were τ b = 0.17 ± 0.08 N m -2, significantly larger than the critical stress threshold necessary for sediment entrainment of 0.04 N m -2. Within the eelgrass bed, τ b = 0.03 ± 0.02 N m -2 and stresses were below the critical stress threshold during 80% of the time period of measurement. Expansion of eelgrass within the coastal bay has thus altered the dynamics of the seafloor from an erosional environment to one that promotes de - position of suspended sediment, enhancing light penetration throughout the water column and creating a positive feedback for eelgrass growth. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Stability and resilience of seagrass meadows to seasonal and interannual dynamics and environmental stress.\n \n \n \n\n\n \n Carr, J. A.; D'Odorico, P.; McGlathery, K. J.; and Wiberg, P. L.\n\n\n \n\n\n\n Journal of Geophysical Research: Biogeosciences. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carr_stability_2012,\n\ttitle = {Stability and resilience of seagrass meadows to seasonal and interannual dynamics and environmental stress},\n\tdoi = {10.1029/2011JG001744},\n\tabstract = {Shallow coastal bays provide habitat for diverse fish and invertebrate populations and are an important source of sediment for surrounding marshes. The sediment dynamics of these bays are strongly affected by seagrass meadows, which limit sediment resuspension, thereby providing a more favorable light environment for their own survival and growth. Due to this positive feedback between seagrass and light conditions, it has been suggested that bare sediment and seagrass meadows are potential alternate stable states of the benthos in shallow coastal bays. To investigate the stability and resilience of seagrass meadows subjected to variation in environmental conditions (e.g., light, temperature), a coupled model of vegetation-sediment-water flow interactions and vegetation growth was developed. The model was used to examine the effect of dynamically varying seasonal and interannual seagrass density on sediment resuspension, water column turbidity, and the subsequent light environment on hourly time steps and then run over decadal time scales. A daily growth model was designed to capture both belowground biomass and the growth and senescence of aboveground biomass structural components (e.g., leaves and stems). This allowed us to investigate how the annual and seasonal variability in shoot and leaf density within a meadow affects the strength of positive feedbacks between seagrass and their light environment. The model demonstrates both the emergence of bistable behavior from 1.6 to 1.8 m mean sea level due to the strength of the positive feedback, as well as the limited resilience of seagrass meadows within this bistable range. Copyright 2012 by the American Geophysical Union.},\n\tjournal = {Journal of Geophysical Research: Biogeosciences},\n\tauthor = {Carr, Joel A. and D'Odorico, Paolo and McGlathery, Karen J. and Wiberg, Patricia L.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n\n\n
\n Shallow coastal bays provide habitat for diverse fish and invertebrate populations and are an important source of sediment for surrounding marshes. The sediment dynamics of these bays are strongly affected by seagrass meadows, which limit sediment resuspension, thereby providing a more favorable light environment for their own survival and growth. Due to this positive feedback between seagrass and light conditions, it has been suggested that bare sediment and seagrass meadows are potential alternate stable states of the benthos in shallow coastal bays. To investigate the stability and resilience of seagrass meadows subjected to variation in environmental conditions (e.g., light, temperature), a coupled model of vegetation-sediment-water flow interactions and vegetation growth was developed. The model was used to examine the effect of dynamically varying seasonal and interannual seagrass density on sediment resuspension, water column turbidity, and the subsequent light environment on hourly time steps and then run over decadal time scales. A daily growth model was designed to capture both belowground biomass and the growth and senescence of aboveground biomass structural components (e.g., leaves and stems). This allowed us to investigate how the annual and seasonal variability in shoot and leaf density within a meadow affects the strength of positive feedbacks between seagrass and their light environment. The model demonstrates both the emergence of bistable behavior from 1.6 to 1.8 m mean sea level due to the strength of the positive feedback, as well as the limited resilience of seagrass meadows within this bistable range. Copyright 2012 by the American Geophysical Union.\n
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\n \n\n \n \n \n \n \n Seed addition facilitates eelgrass recovery in a coastal bay system.\n \n \n \n\n\n \n Orth, R. J.; Moore, K. A.; Marion, S. R.; Wilcox, D. J.; and Parrish, D. B.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{orth_seed_2012,\n\ttitle = {Seed addition facilitates eelgrass recovery in a coastal bay system},\n\tdoi = {10.3354/meps09522},\n\tabstract = {Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those exports. Estimates of annual patch vegetative expansion showed mean estimated diameter increasing at varying rates from 10 to 36 cm yr-1, consistent with rhizome elongation rates reported for Z. marina. Water quality data collected over 7 yr by spatially intensive sampling, as well as fixed-location continuous monitoring, document conditions in all 4 bays that are adequate to support Z. marina growth. In particular, median chlorophyll levels for the entire sampling period were between 5 and 6 μg l-1 for each of the bays, and median turbidity levels, while exhibiting seasonal differences, were between 8 and 9 NTU. The recovery of Z. marina initiated in this coastal bay system may be unique in seagrass recovery studies because of how the recovery was initiated (seeds rather than adult plants), how rapidly it occurred (years rather than decades), and the explicit demonstration of how one meadow modulated water clarity and altered sediments as it developed and expanded. Our results offer a new perspective on the role seeds can play in recovery dynamics at large spatial scales. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A. and Marion, Scott R. and Wilcox, David J. and Parrish, David B.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those exports. Estimates of annual patch vegetative expansion showed mean estimated diameter increasing at varying rates from 10 to 36 cm yr-1, consistent with rhizome elongation rates reported for Z. marina. Water quality data collected over 7 yr by spatially intensive sampling, as well as fixed-location continuous monitoring, document conditions in all 4 bays that are adequate to support Z. marina growth. In particular, median chlorophyll levels for the entire sampling period were between 5 and 6 μg l-1 for each of the bays, and median turbidity levels, while exhibiting seasonal differences, were between 8 and 9 NTU. The recovery of Z. marina initiated in this coastal bay system may be unique in seagrass recovery studies because of how the recovery was initiated (seeds rather than adult plants), how rapidly it occurred (years rather than decades), and the explicit demonstration of how one meadow modulated water clarity and altered sediments as it developed and expanded. Our results offer a new perspective on the role seeds can play in recovery dynamics at large spatial scales. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Nitrogen fixation in restored eelgrass meadows.\n \n \n \n\n\n \n Cole, L. W.; and McGlathery, K. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{cole_nitrogen_2012,\n\ttitle = {Nitrogen fixation in restored eelgrass meadows},\n\tdoi = {10.3354/meps09512},\n\tabstract = {Biological nitrogen (N 2) fixation is the primary input of new nitrogen (N) to marine systems, and is important in meeting the N demands of primary producers. In this study, we determined whether restoration of the eelgrass Zostera marina L. in a shallow coastal bay facilitated increasing rates of N 2 fixation as the meadows aged. Rates of N 2 fixation were measured in a system that had been devoid of eelgrass following local extinction in the 1930s until restoration by seeding began in 2001. Restored meadows of different ages were compared to nearby bare sediment sites during summer peak metabolism over 2 yr. Nutrient addition by N 2 fixation was enhanced as the meadows aged. Rates of N 2 fixation in the older (7 to 8 yr old) meadows were 2.7 times more than the younger (2 to 3 yr old) meadows (average 390 and 146 μmol N m -2 d -1, respectively), and 28 times more than bare sediments (average 14 μmol N m -2 d -1). Heterotrophic epiphyte bacteria fixed approximately 90\\% of the total N 2 in Z. marina meadows of both age classes. Both sediment and epiphyte N 2 fixation were strongly related to Z. marina density and sediment organic content, suggesting that shoot density increases the positive feedback of plant presence on N 2 fixation through the release of organic carbon exudates into the rhizosphere and phyllosphere, and the build up of sediment organic matter also increases. The N provided through fixation represented a large fraction (20.5 to 30\\%) of the total N demand to support eelgrass aboveground growth during this period of peak summertime production. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Cole, Luke W. and McGlathery, Karen J.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Biological nitrogen (N 2) fixation is the primary input of new nitrogen (N) to marine systems, and is important in meeting the N demands of primary producers. In this study, we determined whether restoration of the eelgrass Zostera marina L. in a shallow coastal bay facilitated increasing rates of N 2 fixation as the meadows aged. Rates of N 2 fixation were measured in a system that had been devoid of eelgrass following local extinction in the 1930s until restoration by seeding began in 2001. Restored meadows of different ages were compared to nearby bare sediment sites during summer peak metabolism over 2 yr. Nutrient addition by N 2 fixation was enhanced as the meadows aged. Rates of N 2 fixation in the older (7 to 8 yr old) meadows were 2.7 times more than the younger (2 to 3 yr old) meadows (average 390 and 146 μmol N m -2 d -1, respectively), and 28 times more than bare sediments (average 14 μmol N m -2 d -1). Heterotrophic epiphyte bacteria fixed approximately 90% of the total N 2 in Z. marina meadows of both age classes. Both sediment and epiphyte N 2 fixation were strongly related to Z. marina density and sediment organic content, suggesting that shoot density increases the positive feedback of plant presence on N 2 fixation through the release of organic carbon exudates into the rhizosphere and phyllosphere, and the build up of sediment organic matter also increases. The N provided through fixation represented a large fraction (20.5 to 30%) of the total N demand to support eelgrass aboveground growth during this period of peak summertime production. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Recovery trajectories during state change from bare sediment to eelgrass dominance.\n \n \n \n\n\n \n McGlathery, K. J.; Reynolds, L. K.; Cole, L. W.; Orth, R. J.; Marion, S. R.; and Schwarzschild, A.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{mcglathery_recovery_2012,\n\ttitle = {Recovery trajectories during state change from bare sediment to eelgrass dominance},\n\tdoi = {10.3354/meps09574},\n\tabstract = {Seagrasses are important foundation species in shallow coastal ecosystems that provide critical ecosystem services including stabilizing sediment, sequestering carbon and nutrients, and providing habitat and an energy source for a diverse fauna. We followed the recovery of functional (primary productivity, carbon and nitrogen sequestration, sediment deposition) and structural (shoot density, biomass, plant morphometrics) attributes of Zostera marina (eelgrass) meadows in replicate large plots (0.2 to 0.4 ha) restored by seeding in successive years, resulting in a chrono sequence of sites from 0 (unvegetated) to 9 yr since seeding. Shoot density was the structural metric that changed most significantly, with an initial 4 yr lag, and a rapid, linear increase in plots 6 to 9 yr after seeding. Changes in Z. marina aerial productivity, sediment organic content, and exchangeable ammonium showed a similar trend with an initial 4 yr lag period before differences were observed from initial bare sediment conditions. After 9 yr, Z. marina meadows had 20× higher rates of areal productivity than 1 to 3 yr old meadows, double the organic matter and exchangeable ammonium concentrations, 3× more carbon and 4× more nitrogen, and had accumulated and retained finer particles than bare, unvegetated sediments. These results demonstrate the reinstatement of key ecosystem services with successful large-scale restoration, although none of the parameters reached an asymptote after 9 yr, indicating that at least a decade is required for these attributes to be fully restored, even in an area with high habitat suitability. Survivorship along a depth gradient showed that ∼1.6 m (mean sea level) is the maximum depth limit for Z. marina, which matches the 'tipping point' for survival predicted for this system from a non-linear hydro dynamic/seagrass growth model. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {McGlathery, Karen J. and Reynolds, Laura K. and Cole, Luke W. and Orth, Robert J. and Marion, Scott R. and Schwarzschild, Arthur},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Seagrasses are important foundation species in shallow coastal ecosystems that provide critical ecosystem services including stabilizing sediment, sequestering carbon and nutrients, and providing habitat and an energy source for a diverse fauna. We followed the recovery of functional (primary productivity, carbon and nitrogen sequestration, sediment deposition) and structural (shoot density, biomass, plant morphometrics) attributes of Zostera marina (eelgrass) meadows in replicate large plots (0.2 to 0.4 ha) restored by seeding in successive years, resulting in a chrono sequence of sites from 0 (unvegetated) to 9 yr since seeding. Shoot density was the structural metric that changed most significantly, with an initial 4 yr lag, and a rapid, linear increase in plots 6 to 9 yr after seeding. Changes in Z. marina aerial productivity, sediment organic content, and exchangeable ammonium showed a similar trend with an initial 4 yr lag period before differences were observed from initial bare sediment conditions. After 9 yr, Z. marina meadows had 20× higher rates of areal productivity than 1 to 3 yr old meadows, double the organic matter and exchangeable ammonium concentrations, 3× more carbon and 4× more nitrogen, and had accumulated and retained finer particles than bare, unvegetated sediments. These results demonstrate the reinstatement of key ecosystem services with successful large-scale restoration, although none of the parameters reached an asymptote after 9 yr, indicating that at least a decade is required for these attributes to be fully restored, even in an area with high habitat suitability. Survivorship along a depth gradient showed that ∼1.6 m (mean sea level) is the maximum depth limit for Z. marina, which matches the 'tipping point' for survival predicted for this system from a non-linear hydro dynamic/seagrass growth model. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Modeling the effects of climate change on eelgrass stability and resilience: Future scenarios and leading indicators of collapse.\n \n \n \n\n\n \n Carr, J. A.; D'Odorico, P.; McGlathery, K. J.; and Wiberg, P. L.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{carr_modeling_2012,\n\ttitle = {Modeling the effects of climate change on eelgrass stability and resilience: {Future} scenarios and leading indicators of collapse},\n\tdoi = {10.3354/meps09556},\n\tabstract = {Seagrass meadows influence local hydrodynamics in coastal bays, resulting in a decrease in the shear stress acting on the underlying bed sediment. The reduced sediment suspension and water column turbidity creates a more favorable light environment for further seagrass growth. This positive feedback is strong enough to induce depth-dependent bistable dynamics with 2 possible stable states, an extant meadow and a bare sediment surface. A coupled vegetation-growth hydrodynamic model was used to investigate eelgrass stability and leading indicators of ecosystem shift under the effects of sea-level rise and increases in water temperature associated with climate change. The model was applied to Hog Island Bay, a shallow coastal bay within the Virginia Coast Reserve, USA, where eelgrass restoration efforts are ongoing. The results indicate that while extant eelgrass meadows are likely to tolerate sea-level rise, an increase in the frequency of days when summer water temperature exceeds 30°C will cause more frequent summer die-offs. This increase in the number of higher temperature disturbance events is likely to push a dense meadow initially located within the bistable depth range (1.6 to 1.8 m mean sea level) toward and eventually past a critical bifurcation point, from which recovery is not possible. We identified 2 leading indicators of a meadow nearing this bifurcation point, both associated with the number of leaves per shoot: 'flickering,' which reflects conspicuous fluctuations from one attractor to the other across the threshold, and 'slowing down,' which is the decreased recovery from perturbations as a system gets close to a threshold. Our model indicates that the eelgrass in these coastal bays has limited resilience to increases in water temperatures predicted from current climate change models. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Carr, Joel A. and D'Odorico, Paolo and McGlathery, Karen J. and Wiberg, Patricia L.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Seagrass meadows influence local hydrodynamics in coastal bays, resulting in a decrease in the shear stress acting on the underlying bed sediment. The reduced sediment suspension and water column turbidity creates a more favorable light environment for further seagrass growth. This positive feedback is strong enough to induce depth-dependent bistable dynamics with 2 possible stable states, an extant meadow and a bare sediment surface. A coupled vegetation-growth hydrodynamic model was used to investigate eelgrass stability and leading indicators of ecosystem shift under the effects of sea-level rise and increases in water temperature associated with climate change. The model was applied to Hog Island Bay, a shallow coastal bay within the Virginia Coast Reserve, USA, where eelgrass restoration efforts are ongoing. The results indicate that while extant eelgrass meadows are likely to tolerate sea-level rise, an increase in the frequency of days when summer water temperature exceeds 30°C will cause more frequent summer die-offs. This increase in the number of higher temperature disturbance events is likely to push a dense meadow initially located within the bistable depth range (1.6 to 1.8 m mean sea level) toward and eventually past a critical bifurcation point, from which recovery is not possible. We identified 2 leading indicators of a meadow nearing this bifurcation point, both associated with the number of leaves per shoot: 'flickering,' which reflects conspicuous fluctuations from one attractor to the other across the threshold, and 'slowing down,' which is the decreased recovery from perturbations as a system gets close to a threshold. Our model indicates that the eelgrass in these coastal bays has limited resilience to increases in water temperatures predicted from current climate change models. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Enhancement of sediment suspension and nutrient flux by benthic macrophytes at low biomass.\n \n \n \n\n\n \n Lawson, S. E.; McGlathery, K. J.; and Wiberg, P. L.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{lawson_enhancement_2012,\n\ttitle = {Enhancement of sediment suspension and nutrient flux by benthic macrophytes at low biomass},\n\tdoi = {10.3354/meps09579},\n\tabstract = {In shallow coastal ecosystems where most of the seafloor typically lies within the photic zone, benthic autotrophs dominate primary production and mediate nutrient cycling and sediment stability. Because of their different structure and metabolic rates, the 2 functional groups of benthic macrophytes (seagrasses, macroalgae) have distinct influences on benthic-pelagic coupling. Most research to date in these soft-bottomed systems has focused on mature seagrass meadows where shoot densities are high and on dense macroalgal mats that accumulate in response to eutrophication. Relatively little is known about the influence of low-biomass stands of seagrass and macroalgae on nutrient fluxes and sediment suspension. Using an erosion microcosm with controlled forcing conditions, we tested the effects of the eelgrass Zostera marina L. and the invasive macroalga Gracilaria vermiculophylla on sediment suspension and nutrient fluxes under high-flow conditions. At low densities, G. vermiculophylla increased sediment suspension and increased the nutrient flux from the sediment to the water column. For macroalgae, increased sedi ment suspension is likely due to dislodgement of sediment particles by bedload transport of the algae. In this case, the increase in sediment transport was reflected in an increase in nutrient flux from the sediment, showing that modification of physical forcing by benthic primary producers can also affect nutrient flux. The presence or absence of Z. marina did not have a significant effect on nutrient flux. However, the results suggest that there may be a range of low shoot densities for which storm-like flows increase sediment suspension to values higher than those expected for a bare sediment bed. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Lawson, S. E. and McGlathery, K. J. and Wiberg, P. L.},\n\tyear = {2012},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n In shallow coastal ecosystems where most of the seafloor typically lies within the photic zone, benthic autotrophs dominate primary production and mediate nutrient cycling and sediment stability. Because of their different structure and metabolic rates, the 2 functional groups of benthic macrophytes (seagrasses, macroalgae) have distinct influences on benthic-pelagic coupling. Most research to date in these soft-bottomed systems has focused on mature seagrass meadows where shoot densities are high and on dense macroalgal mats that accumulate in response to eutrophication. Relatively little is known about the influence of low-biomass stands of seagrass and macroalgae on nutrient fluxes and sediment suspension. Using an erosion microcosm with controlled forcing conditions, we tested the effects of the eelgrass Zostera marina L. and the invasive macroalga Gracilaria vermiculophylla on sediment suspension and nutrient fluxes under high-flow conditions. At low densities, G. vermiculophylla increased sediment suspension and increased the nutrient flux from the sediment to the water column. For macroalgae, increased sedi ment suspension is likely due to dislodgement of sediment particles by bedload transport of the algae. In this case, the increase in sediment transport was reflected in an increase in nutrient flux from the sediment, showing that modification of physical forcing by benthic primary producers can also affect nutrient flux. The presence or absence of Z. marina did not have a significant effect on nutrient flux. However, the results suggest that there may be a range of low shoot densities for which storm-like flows increase sediment suspension to values higher than those expected for a bare sediment bed. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Dissolved oxygen fluxes and ecosystem metabolism in an eelgrass (Zostera marina) meadow measured with the eddy correlation technique.\n \n \n \n\n\n \n Hume, A. C.; Berg, P.; and McGlathery, K. J.\n\n\n \n\n\n\n Limnology and Oceanography. 2011.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{hume_dissolved_2011,\n\ttitle = {Dissolved oxygen fluxes and ecosystem metabolism in an eelgrass ({Zostera} marina) meadow measured with the eddy correlation technique},\n\tdoi = {10.4319/lo.2011.56.1.0086},\n\tabstract = {Dissolved oxygen (DO) fluxes were measured by eddy correlation to estimate net ecosystem metabolism (NEM) during summer in a restored eelgrass (Zostera marina) meadow and a nearby, unvegetated sediment. This technique measures benthic fluxes under true in situ light and hydrodynamic conditions, integrates over a large area (typically {\\textbackslash}textgreater 100 m2), and captures short-term variations. DO fluxes measured through eight 24-h periods showed pronounced temporal variation driven by light and local hydrodynamics on multiple scales: hour-to-hour, within each daily cycle, and between deployments. The magnitude of variation between hours during single deployments equaled that between deployments, indicating that short-term variation must be included for metabolism estimates to be accurate. DO flux variability was significantly correlated to mean current velocity for the seagrass site and to significant wave height for the unvegetated site. Fluxes measured in low-flow conditions analogous to many chamber and core incubations underestimated those measured in higher-flow conditions typical of in situ conditions by a factor of 2-6. Rates of gross primary production (GPP), respiration (R), and NEM varied substantially between individual deployments, reflecting variations in light and hydrodynamic conditions, and daily values of GPP and R for individual deployments were tightly linked. Average daily NEM of the seagrass site was higher than that of the unvegetated site; the seagrass site was in metabolic balance, and the unvegetated site showed a tendency toward net heterotrophy during this midsummer period. © 2011, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Hume, Andrew C. and Berg, Peter and McGlathery, Karen J.},\n\tyear = {2011},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Dissolved oxygen (DO) fluxes were measured by eddy correlation to estimate net ecosystem metabolism (NEM) during summer in a restored eelgrass (Zostera marina) meadow and a nearby, unvegetated sediment. This technique measures benthic fluxes under true in situ light and hydrodynamic conditions, integrates over a large area (typically \\textgreater 100 m2), and captures short-term variations. DO fluxes measured through eight 24-h periods showed pronounced temporal variation driven by light and local hydrodynamics on multiple scales: hour-to-hour, within each daily cycle, and between deployments. The magnitude of variation between hours during single deployments equaled that between deployments, indicating that short-term variation must be included for metabolism estimates to be accurate. DO flux variability was significantly correlated to mean current velocity for the seagrass site and to significant wave height for the unvegetated site. Fluxes measured in low-flow conditions analogous to many chamber and core incubations underestimated those measured in higher-flow conditions typical of in situ conditions by a factor of 2-6. Rates of gross primary production (GPP), respiration (R), and NEM varied substantially between individual deployments, reflecting variations in light and hydrodynamic conditions, and daily values of GPP and R for individual deployments were tightly linked. Average daily NEM of the seagrass site was higher than that of the unvegetated site; the seagrass site was in metabolic balance, and the unvegetated site showed a tendency toward net heterotrophy during this midsummer period. © 2011, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Long-term reductions in anthropogenic nutrients link to improvements in Chesapeake Bay habitat.\n \n \n \n\n\n \n Ruhl, H. a; and Rybicki, N. B\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences of the United States of America, 107(38): 16566–16570. 2010.\n Number: 38 ISBN: 1091-6490 (Electronic)${\\}backslash$r0027-8424 (Linking)\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{ruhl_long-term_2010,\n\ttitle = {Long-term reductions in anthropogenic nutrients link to improvements in {Chesapeake} {Bay} habitat.},\n\tvolume = {107},\n\tdoi = {10.1073/pnas.1003590107},\n\tabstract = {Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990-2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.},\n\tnumber = {38},\n\tjournal = {Proceedings of the National Academy of Sciences of the United States of America},\n\tauthor = {Ruhl, Henry a and Rybicki, Nancy B},\n\tyear = {2010},\n\tpmid = {20823243},\n\tnote = {Number: 38\nISBN: 1091-6490 (Electronic)\\${\\textbackslash}backslash\\$r0027-8424 (Linking)},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n\tpages = {16566--16570},\n}\n\n
\n
\n\n\n
\n Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990-2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Feedback effects in a coastal canopy-forming submersed plant bed.\n \n \n \n\n\n \n Gruber, R. K.; and Kemp, W. M.\n\n\n \n\n\n\n Limnology and Oceanography. 2010.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{gruber_feedback_2010,\n\ttitle = {Feedback effects in a coastal canopy-forming submersed plant bed},\n\tdoi = {10.4319/lo.2010.55.6.2285},\n\tabstract = {Although physical and biogeochemical properties of an environment determine distribution and health of biota, some organisms modify habitat conditions through complex interactions with their surroundings. We quantified effects of the canopy-forming submersed plant species Stuckenia pectinata on local hydrodynamics and explored resulting positive and negative feedbacks on plant growth. Measurements of waves and tidal currents were made outside, at the edge of, and within a plant bed located in the mesohaline region of Chesapeake Bay. Clear feedback effects on light, nutrients, and sediments were observed, and were found to vary seasonally with plant growth cycle. During the June period of peak plant biomass, significant wave heights were attenuated by ∼37\\% within the plant stand; this resulted in an ∼60\\% reduction of total suspended solids, which was stable and relatively unaffected by periods of high wind speed or water depth. Deployments of artificial substrates showed that epiphytic accumulation was greatly reduced within the plant bed, further increasing available light for plants to 25\\% of incoming irradiance (as compared to 0.2\\% outside the plant bed). In addition, higher particle trapping rates and sediment organic content augmented bed pore-water nutrient pools (CO2, NHz 4+ PO43-) sufficiently to satisfy plant demands. These processes generated negative feedback effects on plant growth, including elevated pore-water sulfide ({\\textbackslash}textgreater 700 μmol L-1) and depressed water-column O2 concentrations ({\\textbackslash}textless 2 mg L -1), but levels were ephemeral and generally outside reported stress thresholds. Dominant positive feedbacks provide an explanation for bed survival in this environment despite degraded water quality during summer months. © 2010, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Gruber, Renee K. and Kemp, W. Michael},\n\tyear = {2010},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Although physical and biogeochemical properties of an environment determine distribution and health of biota, some organisms modify habitat conditions through complex interactions with their surroundings. We quantified effects of the canopy-forming submersed plant species Stuckenia pectinata on local hydrodynamics and explored resulting positive and negative feedbacks on plant growth. Measurements of waves and tidal currents were made outside, at the edge of, and within a plant bed located in the mesohaline region of Chesapeake Bay. Clear feedback effects on light, nutrients, and sediments were observed, and were found to vary seasonally with plant growth cycle. During the June period of peak plant biomass, significant wave heights were attenuated by ∼37% within the plant stand; this resulted in an ∼60% reduction of total suspended solids, which was stable and relatively unaffected by periods of high wind speed or water depth. Deployments of artificial substrates showed that epiphytic accumulation was greatly reduced within the plant bed, further increasing available light for plants to 25% of incoming irradiance (as compared to 0.2% outside the plant bed). In addition, higher particle trapping rates and sediment organic content augmented bed pore-water nutrient pools (CO2, NHz 4+ PO43-) sufficiently to satisfy plant demands. These processes generated negative feedback effects on plant growth, including elevated pore-water sulfide (\\textgreater 700 μmol L-1) and depressed water-column O2 concentrations (\\textless 2 mg L -1), but levels were ephemeral and generally outside reported stress thresholds. Dominant positive feedbacks provide an explanation for bed survival in this environment despite degraded water quality during summer months. © 2010, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Effects of sediment organic content and hydrodynamic conditions on the growth and distribution of Zostera marina.\n \n \n \n\n\n \n Wicks, E. C.; Koch, E. W.; O'Neil, J. M.; and Elliston, K.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2009.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{wicks_effects_2009,\n\ttitle = {Effects of sediment organic content and hydrodynamic conditions on the growth and distribution of {Zostera} marina},\n\tdoi = {10.3354/meps07885},\n\tabstract = {The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content {\\textbackslash}textgreater 4\\%, especially compared with areas with sediment organic content {\\textbackslash}textless 4\\%. In contrast, in a mesocosm experiment, Z. marina thrived in organic rich (4 to 6\\%) sediment, developing long leaves and disproportionately short roots. Such plants have high drag and low anchoring capacity. As a result, Z manna plants grown in organic rich sediment are more likely to be dislodged than are plants grown in organic poor sand. We hypothesize that when organic rich sediments are found in hydrodynamically active areas, a mismatch occurs between plant morphology and the physical environment, leading to the loss of seagrasses due to uprooting. Therefore, sediment organic content limitations in seagrass habitats need to be evaluated within the local hydrodynamic settings. Fine organic sediment may be less limiting to seagrasses in quiescent waters while sand with low organic content may be required for seagrass survival in hydrodynamically active areas. © Inter-Research 2009.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Wicks, E. Caroline and Koch, Evamaria W. and O'Neil, Judy M. and Elliston, Kahla},\n\tyear = {2009},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n The hypothesis that sediment organic content is limiting growth and distribution of the seagrass Zostera marina was tested in Chincoteague Bay, Maryland, and in a controlled mesocosm experiment. In the field, Z. marina was usually absent from areas with sediment organic content \\textgreater 4%, especially compared with areas with sediment organic content \\textless 4%. In contrast, in a mesocosm experiment, Z. marina thrived in organic rich (4 to 6%) sediment, developing long leaves and disproportionately short roots. Such plants have high drag and low anchoring capacity. As a result, Z manna plants grown in organic rich sediment are more likely to be dislodged than are plants grown in organic poor sand. We hypothesize that when organic rich sediments are found in hydrodynamically active areas, a mismatch occurs between plant morphology and the physical environment, leading to the loss of seagrasses due to uprooting. Therefore, sediment organic content limitations in seagrass habitats need to be evaluated within the local hydrodynamic settings. Fine organic sediment may be less limiting to seagrasses in quiescent waters while sand with low organic content may be required for seagrass survival in hydrodynamically active areas. © Inter-Research 2009.\n
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\n \n\n \n \n \n \n \n Factors influencing reproduction in American wild celery: A synthesis.\n \n \n \n\n\n \n McFarland, D. G.; and Shafer, D. J.\n\n\n \n\n\n\n Journal of Aquatic Plant Management. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{mcfarland_factors_2008,\n\ttitle = {Factors influencing reproduction in {American} wild celery: {A} synthesis},\n\tabstract = {Dramatic declines in American wild celery (Vallisneria americana Michaux), a native submersed aquatic plant, have been widely reported in the United States since the 1960s, especially from the Midwest to the Northeast. Though methods for restoration are being developed and implemented, progress has been hampered by the need for greater understanding of the species' biological traits and response to environmental change. Here, we review available literature on reproductive ecology of wild celery, focusing on environmental influences on the production and early stages of growth of different propagule types. A background profile of the species describes its ecological importance, field characteristics, taxonomy, life history, and geographical distribution. Critical gaps in present knowledge indicate much has yet to be learned to identify different ecotypes of wild celery based on phenological and genetic distinctions. Further research is also needed to assess potential establishment from seed for consideration as an alternative to (or supplement to) vegetative propagules in restoration strategies.},\n\tjournal = {Journal of Aquatic Plant Management},\n\tauthor = {McFarland, Dwilette G. and Shafer, D. J.},\n\tyear = {2008},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Dramatic declines in American wild celery (Vallisneria americana Michaux), a native submersed aquatic plant, have been widely reported in the United States since the 1960s, especially from the Midwest to the Northeast. Though methods for restoration are being developed and implemented, progress has been hampered by the need for greater understanding of the species' biological traits and response to environmental change. Here, we review available literature on reproductive ecology of wild celery, focusing on environmental influences on the production and early stages of growth of different propagule types. A background profile of the species describes its ecological importance, field characteristics, taxonomy, life history, and geographical distribution. Critical gaps in present knowledge indicate much has yet to be learned to identify different ecotypes of wild celery based on phenological and genetic distinctions. Further research is also needed to assess potential establishment from seed for consideration as an alternative to (or supplement to) vegetative propagules in restoration strategies.\n
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\n \n\n \n \n \n \n \n Using the aquatic macrophyte Vallisneria americana (wild celery) as a nutrient bioindicator.\n \n \n \n\n\n \n Benson, E. R.; O'Neil, J. M.; and Dennison, W. C.\n\n\n \n\n\n\n Hydrobiologia. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{benson_using_2008,\n\ttitle = {Using the aquatic macrophyte {Vallisneria} americana (wild celery) as a nutrient bioindicator},\n\tdoi = {10.1007/s10750-007-9095-0},\n\tabstract = {Human sewage and septic waste are significant sources of nutrient loading to many aquatic ecosystems. Ecologically relevant nitrogen sources can be traced by analyzing nitrogen stable isotope ratios (δ15N signatures) in aquatic plants. Elevated δ15N signatures can suggest increased uptake of nitrogen derived from human and/or animal waste. In the current study, Vallisneria americana, a freshwater angiosperm, was collected from several locations in Upper Saranac Lake, NY, USA. Samples were also collected from Lake George, NY and the Sassafras River, MD, USA. Plant material was analyzed for δ15N and \\% N; some samples were also analyzed for δ13C, \\% C, and \\% P. Results suggest that there is variation in septic inputs to Upper Saranac Lake, with some areas of the lake receiving more input than others. Results also show that increased watershed population density is correlated with elevated δ15N signatures of Vallisneria americana. Taken together, these results suggest that nitrogen stable isotope analysis of aquatic plant tissue is an effective method for assessing and monitoring septic inputs to freshwater ecosystems. © 2007 Springer Science+Business Media B.V.},\n\tjournal = {Hydrobiologia},\n\tauthor = {Benson, Emily R. and O'Neil, Judith M. and Dennison, William C.},\n\tyear = {2008},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Human sewage and septic waste are significant sources of nutrient loading to many aquatic ecosystems. Ecologically relevant nitrogen sources can be traced by analyzing nitrogen stable isotope ratios (δ15N signatures) in aquatic plants. Elevated δ15N signatures can suggest increased uptake of nitrogen derived from human and/or animal waste. In the current study, Vallisneria americana, a freshwater angiosperm, was collected from several locations in Upper Saranac Lake, NY, USA. Samples were also collected from Lake George, NY and the Sassafras River, MD, USA. Plant material was analyzed for δ15N and % N; some samples were also analyzed for δ13C, % C, and % P. Results suggest that there is variation in septic inputs to Upper Saranac Lake, with some areas of the lake receiving more input than others. Results also show that increased watershed population density is correlated with elevated δ15N signatures of Vallisneria americana. Taken together, these results suggest that nitrogen stable isotope analysis of aquatic plant tissue is an effective method for assessing and monitoring septic inputs to freshwater ecosystems. © 2007 Springer Science+Business Media B.V.\n
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\n \n\n \n \n \n \n \n Seagrass Habitats.\n \n \n \n\n\n \n McGlathery, K. J.\n\n\n \n\n\n\n In Nitrogen in the Marine Environment. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@incollection{mcglathery_seagrass_2008,\n\ttitle = {Seagrass {Habitats}},\n\tisbn = {978-0-12-372522-6},\n\tabstract = {This chapter focuses on the Seagrasses habitats, which affect the rates and pathways of nitrogen (N) cycling in lagoons and estuaries by: the temporary retention of N in their tissue and the subsequent fate of this tissue and the release of dissolved organic carbon (DOC) and oxygen from roots to the sediments that alters bacterial activities. For many systems, N assimilation rates are of the same magnitude as watershed and atmospheric N loading, and thus seagrasses are a critical part of the estuarine filter. Seagrasses slow the transport of Nto the nearcoastal zone, and appear to be net sinks of N on daily to seasonal time scales. This sink role is regulated by photosynthesis and nutrient uptake, with meadows acting as a sink during the day and during the active growing season. Whether seagrass meadows are a net sink on annual basis appears to depend on the developmental stage (young vs. old) and on nutrient conditions, with meadows in eutrophic environments possibly becoming a source of nutrients to the water column. At the plant level, one need to know more about exudation of dissolved nitrogen from living seagrass tissue and its role in stimulating heterotrophic activity in the water column and sediments. Over the last two decades good understanding of N controls on the production have developed, morphology and dynamics of seagrass ecosystems, and on the feedbacks of seagrass metabolism on N-cycling processes. However, there is lack of sufficient empirical information to predict the changes in N-cycling in seagrass-vegetated systems that will result from eutrophication. © 2008 Copyright © 2008 Elsevier Inc. All rights reserved..},\n\tbooktitle = {Nitrogen in the {Marine} {Environment}},\n\tauthor = {McGlathery, Karen J.},\n\tyear = {2008},\n\tdoi = {10.1016/B978-0-12-372522-6.00023-2},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n This chapter focuses on the Seagrasses habitats, which affect the rates and pathways of nitrogen (N) cycling in lagoons and estuaries by: the temporary retention of N in their tissue and the subsequent fate of this tissue and the release of dissolved organic carbon (DOC) and oxygen from roots to the sediments that alters bacterial activities. For many systems, N assimilation rates are of the same magnitude as watershed and atmospheric N loading, and thus seagrasses are a critical part of the estuarine filter. Seagrasses slow the transport of Nto the nearcoastal zone, and appear to be net sinks of N on daily to seasonal time scales. This sink role is regulated by photosynthesis and nutrient uptake, with meadows acting as a sink during the day and during the active growing season. Whether seagrass meadows are a net sink on annual basis appears to depend on the developmental stage (young vs. old) and on nutrient conditions, with meadows in eutrophic environments possibly becoming a source of nutrients to the water column. At the plant level, one need to know more about exudation of dissolved nitrogen from living seagrass tissue and its role in stimulating heterotrophic activity in the water column and sediments. Over the last two decades good understanding of N controls on the production have developed, morphology and dynamics of seagrass ecosystems, and on the feedbacks of seagrass metabolism on N-cycling processes. However, there is lack of sufficient empirical information to predict the changes in N-cycling in seagrass-vegetated systems that will result from eutrophication. © 2008 Copyright © 2008 Elsevier Inc. All rights reserved..\n
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\n \n\n \n \n \n \n \n Effects of pre-existing submersed vegetation and propagule pressure on the invasion success of Hydrilla verticillata.\n \n \n \n\n\n \n Chadwell, T. B.; and Engelhardt, K. A.\n\n\n \n\n\n\n Journal of Applied Ecology. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{chadwell_effects_2008,\n\ttitle = {Effects of pre-existing submersed vegetation and propagule pressure on the invasion success of {Hydrilla} verticillata},\n\tdoi = {10.1111/j.1365-2664.2007.01384.x},\n\tabstract = {1. With biological invasions causing widespread problems in ecosystems, methods to curb the colonization success of invasive species are needed. The effective management of invasive species will require an integrated approach that restores community structure and ecosystem processes while controlling propagule pressure of non-native species. 2. We tested the hypotheses that restoring native vegetation and minimizing propagule pressure of invasive species slows the establishment of an invader. In field and greenhouse experiments, we evaluated (i) the effects of a native submersed aquatic plant species, Vallisneria americana, on the colonization success of a non-native species, Hydrilla verticillata; and (ii) the effects of H. verticillata propagule density on its colonization success. 3. Results from the greenhouse experiment showed that V. americana decreased H. verticillata colonization through nutrient draw-down in the water column of closed mesocosms, although data from the field experiment, located in a tidal freshwater region of Chesapeake Bay that is open to nutrient fluxes, suggested that V. americana did not negatively impact H. verticillata colonization. However, H. verticillata colonization was greater in a treatment of plastic V. americana look-alikes, suggesting that the canopy of V. americana can physically capture H. verticillata fragments. Thus pre-emption effects may be less clear in the field experiment because of complex interactions between competitive and facilitative effects in combination with continuous nutrient inputs from tides and rivers that do not allow nutrient draw-down to levels experienced in the greenhouse. 4. Greenhouse and field tests differed in the timing, duration and density of propagule inputs. However, irrespective of these differences, propagule pressure of the invader affected colonization success except in situations when the native species could draw-down nutrients in closed greenhouse mesocosms. In that case, no propagules were able to colonize. 5. Synthesis and applications. We have shown that reducing propagule pressure through targeted management should be considered to slow the spread of invasive species. This, in combination with restoration of native species, may be the best defence against non-native species invasion. Thus a combined strategy of targeted control and promotion of native plant growth is likely to be the most sustainable and cost-effective form of invasive species management. © 2007 The Authors.},\n\tjournal = {Journal of Applied Ecology},\n\tauthor = {Chadwell, Todd B. and Engelhardt, Katharina A.M.},\n\tyear = {2008},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n 1. With biological invasions causing widespread problems in ecosystems, methods to curb the colonization success of invasive species are needed. The effective management of invasive species will require an integrated approach that restores community structure and ecosystem processes while controlling propagule pressure of non-native species. 2. We tested the hypotheses that restoring native vegetation and minimizing propagule pressure of invasive species slows the establishment of an invader. In field and greenhouse experiments, we evaluated (i) the effects of a native submersed aquatic plant species, Vallisneria americana, on the colonization success of a non-native species, Hydrilla verticillata; and (ii) the effects of H. verticillata propagule density on its colonization success. 3. Results from the greenhouse experiment showed that V. americana decreased H. verticillata colonization through nutrient draw-down in the water column of closed mesocosms, although data from the field experiment, located in a tidal freshwater region of Chesapeake Bay that is open to nutrient fluxes, suggested that V. americana did not negatively impact H. verticillata colonization. However, H. verticillata colonization was greater in a treatment of plastic V. americana look-alikes, suggesting that the canopy of V. americana can physically capture H. verticillata fragments. Thus pre-emption effects may be less clear in the field experiment because of complex interactions between competitive and facilitative effects in combination with continuous nutrient inputs from tides and rivers that do not allow nutrient draw-down to levels experienced in the greenhouse. 4. Greenhouse and field tests differed in the timing, duration and density of propagule inputs. However, irrespective of these differences, propagule pressure of the invader affected colonization success except in situations when the native species could draw-down nutrients in closed greenhouse mesocosms. In that case, no propagules were able to colonize. 5. Synthesis and applications. We have shown that reducing propagule pressure through targeted management should be considered to slow the spread of invasive species. This, in combination with restoration of native species, may be the best defence against non-native species invasion. Thus a combined strategy of targeted control and promotion of native plant growth is likely to be the most sustainable and cost-effective form of invasive species management. © 2007 The Authors.\n
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\n \n\n \n \n \n \n \n Environmental Factors Affecting Recent Summertime Eelgrass Diebacks in the Lower Chesapeake Bay: Implications for Long-term Persistence.\n \n \n \n\n\n \n Moore, K. A.; and Jarvis, J. C.\n\n\n \n\n\n\n Journal of Coastal Research. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_environmental_2008,\n\ttitle = {Environmental {Factors} {Affecting} {Recent} {Summertime} {Eelgrass} {Diebacks} in the {Lower} {Chesapeake} {Bay}: {Implications} for {Long}-term {Persistence}},\n\tdoi = {10.2112/si55-014},\n\tabstract = {We investigated the effects of several environmental factors on eelgrass abundance before, during, and after wide,I-Oft oft spread eelgrass diebacks during the unusually hot summer of 2005 in the Chesapeake Bay National Estuarine Research Reserve in Virginia. Systematic sampling with fixed transects was used to investigate changes in eelgrass abundance at downriver and upriver regions of the York River Estuary. Concurrently, continuous and discreet measurements of water quality were made at fixed stations in each area within the eelgrass beds from 2004 through 2006. Results indicate nearly complete eelgrass vegetative dieback during the July-August period of 2005, in contrast to the more seasonal and typical declines in the summer of 2004. Losses were greatest in the deeper areas of the beds and at the upriver site where light availabilities were lowest. Recovery of eelgrass during 2006 was greater in the downriver area, especially at mid-bed depths. By the fall of 2006, no shoot vegetation remained at the upriver site. In 2005, the frequency and duration of water temperatures exceeding 30 degrees C were significantly greater than that of 2004 and 2006. Additionally, the frequencies of low dissolved oxygen excursions of 1-3 mg L(-1) during this period were greater in 2005 than 2004 or 2006. These results suggest that eelgrass populations in this estuary are growing near their physiological tolerances. Therefore, the combined effects of short-term exposures to very high summer temperatures, compounded by reduced oxygen and light conditions, may lead to long-term declines of this species from this system.},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Moore, Kenneth A. and Jarvis, Jessie C.},\n\tyear = {2008},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n We investigated the effects of several environmental factors on eelgrass abundance before, during, and after wide,I-Oft oft spread eelgrass diebacks during the unusually hot summer of 2005 in the Chesapeake Bay National Estuarine Research Reserve in Virginia. Systematic sampling with fixed transects was used to investigate changes in eelgrass abundance at downriver and upriver regions of the York River Estuary. Concurrently, continuous and discreet measurements of water quality were made at fixed stations in each area within the eelgrass beds from 2004 through 2006. Results indicate nearly complete eelgrass vegetative dieback during the July-August period of 2005, in contrast to the more seasonal and typical declines in the summer of 2004. Losses were greatest in the deeper areas of the beds and at the upriver site where light availabilities were lowest. Recovery of eelgrass during 2006 was greater in the downriver area, especially at mid-bed depths. By the fall of 2006, no shoot vegetation remained at the upriver site. In 2005, the frequency and duration of water temperatures exceeding 30 degrees C were significantly greater than that of 2004 and 2006. Additionally, the frequencies of low dissolved oxygen excursions of 1-3 mg L(-1) during this period were greater in 2005 than 2004 or 2006. These results suggest that eelgrass populations in this estuary are growing near their physiological tolerances. Therefore, the combined effects of short-term exposures to very high summer temperatures, compounded by reduced oxygen and light conditions, may lead to long-term declines of this species from this system.\n
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\n \n\n \n \n \n \n \n A nearshore model to investigate the effects of seagrass bed geometry on wave attenuation and suspended sediment transport.\n \n \n \n\n\n \n Chen, S. N.; Sanford, L. P.; Koch, E. W.; Shi, F.; and North, E. W.\n\n\n \n\n\n\n Estuaries and Coasts. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{chen_nearshore_2007,\n\ttitle = {A nearshore model to investigate the effects of seagrass bed geometry on wave attenuation and suspended sediment transport},\n\tdoi = {10.1007/BF02700172},\n\tabstract = {The effects of seagrass bed geometry on wave attenuation and suspended sediment transport were investigated using a modified Nearshore Community Model (NearCoM). The model was enhanced to account for cohesive sediment erosion and deposition, sediment transport, combined wave and current shear stresses, and seagrass effects on drag. Expressions for seagrass drag as a function of seagrass shoot density and canopy height were derived from published flume studies of model vegetation. The predicted reduction of volume flux for steady flow through a bed agreed reasonably well with a separate flume study. Predicted wave attenuation qualitatively captured seasonal patterns observed in the field: wave attenuation peaked during the flowering season and decreased as shoot density and canopy height decreased. Model scenarios whh idealized bathymetries demonstrated that, when wave orbital velocities and the seagrass canopy interact, increasing seagrass bed width in the direction of wave propagation results in higher wave attenuation, and increasing incoming wave height results in higher relative wave attenuation. The model also predicted lower skin friction, reduced erosion rates, and higher bottom sediment accumulation within and behind the bed. Reduced erosion rates within seagrass beds have been reported, but reductions in stress behind the bed require further studies for verification. Model results suggest that the mechanism of sediment trapping by seagrass beds is more complex than reduced erosion rates alone; it also requires suspended sediment sources outside of the bed and horizontal transport into the bed. © 2007 Estuarine Research Federation.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Chen, Shih Nan and Sanford, Lawrence P. and Koch, Evamaria W. and Shi, Fengyan and North, Elizabeth W.},\n\tyear = {2007},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The effects of seagrass bed geometry on wave attenuation and suspended sediment transport were investigated using a modified Nearshore Community Model (NearCoM). The model was enhanced to account for cohesive sediment erosion and deposition, sediment transport, combined wave and current shear stresses, and seagrass effects on drag. Expressions for seagrass drag as a function of seagrass shoot density and canopy height were derived from published flume studies of model vegetation. The predicted reduction of volume flux for steady flow through a bed agreed reasonably well with a separate flume study. Predicted wave attenuation qualitatively captured seasonal patterns observed in the field: wave attenuation peaked during the flowering season and decreased as shoot density and canopy height decreased. Model scenarios whh idealized bathymetries demonstrated that, when wave orbital velocities and the seagrass canopy interact, increasing seagrass bed width in the direction of wave propagation results in higher wave attenuation, and increasing incoming wave height results in higher relative wave attenuation. The model also predicted lower skin friction, reduced erosion rates, and higher bottom sediment accumulation within and behind the bed. Reduced erosion rates within seagrass beds have been reported, but reductions in stress behind the bed require further studies for verification. Model results suggest that the mechanism of sediment trapping by seagrass beds is more complex than reduced erosion rates alone; it also requires suspended sediment sources outside of the bed and horizontal transport into the bed. © 2007 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Top-down and bottom-up controls on sediment organic matter composition in an experimental seagrass ecosystem.\n \n \n \n\n\n \n Spivak, A. C.; Canuel, E. A.; Duffy, J. E.; and Richardson, J. P.\n\n\n \n\n\n\n Limnology and Oceanography. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{spivak_top-down_2007,\n\ttitle = {Top-down and bottom-up controls on sediment organic matter composition in an experimental seagrass ecosystem},\n\tdoi = {10.4319/lo.2007.52.6.2595},\n\tabstract = {We tested the singular and interactive effects of resource availability (light) and community composition (food chain length and herbivore species richness) on eelgrass (Zostera marina) ecosystem properties and functioning with an experimental mesocosm system. Food chain length was manipulated through the presence or absence of blue crab (Callinectes sapidus) predators, whereas grazer species richness varied across three levels (zero, two, or four crustacean species). We found important and interacting effects of bottom-up and top-down forcings on sediment organic matter (SOM) composition. Light increased eelgrass and algal biomass and sediment organic carbon and nitrogen content. Increasing grazer diversity generally decreased algal biomass and ecosystem production but interacted with food chain length (i.e., presence of predatory crabs) and light. Predators generally increased algal biomass and ecosystem production through a trophic cascade, which was stronger at high grazer diversity and under ambient light. SOM composition, determined with fatty acid (FA) biomarkers, was sensitive to all manipulated variables. Increasing grazer species richness often decreased the contributions of FAs derived from plant and algal sources, whereas increasing light had the opposite effect. Food chain length was generally a less important determinant of SOM composition than light, although predators did increase FAs representative of heterotrophic bacteria. Overall, resource availability and epibenthic community composition strongly influenced organic matter cycling, SOM composition, and the bacterial community in seagrass-bed sediments. © 2007, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Spivak, Amanda C. and Canuel, Elizabeth A. and Duffy, J. Emmett and Richardson, J. Paul},\n\tyear = {2007},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n We tested the singular and interactive effects of resource availability (light) and community composition (food chain length and herbivore species richness) on eelgrass (Zostera marina) ecosystem properties and functioning with an experimental mesocosm system. Food chain length was manipulated through the presence or absence of blue crab (Callinectes sapidus) predators, whereas grazer species richness varied across three levels (zero, two, or four crustacean species). We found important and interacting effects of bottom-up and top-down forcings on sediment organic matter (SOM) composition. Light increased eelgrass and algal biomass and sediment organic carbon and nitrogen content. Increasing grazer diversity generally decreased algal biomass and ecosystem production but interacted with food chain length (i.e., presence of predatory crabs) and light. Predators generally increased algal biomass and ecosystem production through a trophic cascade, which was stronger at high grazer diversity and under ambient light. SOM composition, determined with fatty acid (FA) biomarkers, was sensitive to all manipulated variables. Increasing grazer species richness often decreased the contributions of FAs derived from plant and algal sources, whereas increasing light had the opposite effect. Food chain length was generally a less important determinant of SOM composition than light, although predators did increase FAs representative of heterotrophic bacteria. Overall, resource availability and epibenthic community composition strongly influenced organic matter cycling, SOM composition, and the bacterial community in seagrass-bed sediments. © 2007, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Eutrophication in shallow coastal bays and lagoons: The role of plants in the coastal filter.\n \n \n \n\n\n \n McGlathery, K. J.; Sundbäck, K.; and Anderson, I. C.\n\n\n \n\n\n\n 2007.\n Publication Title: Marine Ecology Progress Series\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{mcglathery_eutrophication_2007,\n\ttitle = {Eutrophication in shallow coastal bays and lagoons: {The} role of plants in the coastal filter},\n\tabstract = {Nutrient loading to coastal bay ecosystems is of a similar magnitude as that to deeper, river-fed estuaries, yet our understanding of the eutrophication process in these shallow systems lags far behind. In this synthesis, we focus on one type of biotic feedback that influences eutrophication patterns in coastal bays - the important role of primary producers in the 'coastal filter'. We discuss the 2 aspects of plant-mediated nutrient cycling as eutrophication induces a shift in primary producer dominance: (1) the fate of nutrients bound in plant biomass, and (2) the effects of primary producers on biogeochemical processes that influence nutrient retention. We suggest the following generalizations as eutrophication proceeds in coastal bays: (1) Long-term retention of recalcitrant dissolved and particulate organic matter will decline as seagrasses are replaced by algae with less refractory material. (2) Benthic grazers buffer the early effects of nutrient enrichment, but consumption rates will decline as physico-chemical conditions stress consumer populations. (3) Mass transport of plant-bound nutrients will increase because attached perennial macrophytes will be replaced by unattached ephemeral algae that move with the water. (4) Denitrification will be an unimportant sink for N because primary producers typically outcompete bacteria for available N, and partitioning of nitrate reduction will shift to dissimilatory nitrate reduction to ammonium in later stages of eutrophication. In tropical/subtropical systems dominated by carbonate sediments, eutrophication will likely result in a positive feedback where increased sulfate reduction and sulfide accumulation in sediments will decrease P adsorption to Fe and enhance the release of P to the overlying water. © Inter-Research 2007.},\n\tauthor = {McGlathery, Karen J. and Sundbäck, Kristina and Anderson, Iris C.},\n\tyear = {2007},\n\tdoi = {10.3354/meps07132},\n\tnote = {Publication Title: Marine Ecology Progress Series},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Nutrient loading to coastal bay ecosystems is of a similar magnitude as that to deeper, river-fed estuaries, yet our understanding of the eutrophication process in these shallow systems lags far behind. In this synthesis, we focus on one type of biotic feedback that influences eutrophication patterns in coastal bays - the important role of primary producers in the 'coastal filter'. We discuss the 2 aspects of plant-mediated nutrient cycling as eutrophication induces a shift in primary producer dominance: (1) the fate of nutrients bound in plant biomass, and (2) the effects of primary producers on biogeochemical processes that influence nutrient retention. We suggest the following generalizations as eutrophication proceeds in coastal bays: (1) Long-term retention of recalcitrant dissolved and particulate organic matter will decline as seagrasses are replaced by algae with less refractory material. (2) Benthic grazers buffer the early effects of nutrient enrichment, but consumption rates will decline as physico-chemical conditions stress consumer populations. (3) Mass transport of plant-bound nutrients will increase because attached perennial macrophytes will be replaced by unattached ephemeral algae that move with the water. (4) Denitrification will be an unimportant sink for N because primary producers typically outcompete bacteria for available N, and partitioning of nitrate reduction will shift to dissimilatory nitrate reduction to ammonium in later stages of eutrophication. In tropical/subtropical systems dominated by carbonate sediments, eutrophication will likely result in a positive feedback where increased sulfate reduction and sulfide accumulation in sediments will decrease P adsorption to Fe and enhance the release of P to the overlying water. © Inter-Research 2007.\n
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\n \n\n \n \n \n \n \n Effects of a Prorocentrum minimum bloom on light availability for and potential impacts on submersed aquatic vegetation in upper Chesapeake Bay.\n \n \n \n\n\n \n Gallegos, C. L.; and Bergstrom, P. W.\n\n\n \n\n\n\n In Harmful Algae, 2005. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@inproceedings{gallegos_effects_2005,\n\ttitle = {Effects of a {Prorocentrum} minimum bloom on light availability for and potential impacts on submersed aquatic vegetation in upper {Chesapeake} {Bay}},\n\tdoi = {10.1016/j.hal.2004.08.016},\n\tabstract = {Extraordinary spring blooms of the dinoflagellate Prorocentrum minimum have been a recurring feature of upper Chesapeake Bay for many years. Though not thought to be toxic in Chesapeake Bay, these blooms produce extraordinarily high concentrations of chlorophyll, thereby increasing light attenuation. A particularly large event occurred in the spring of 2000. Here, we assess the impact of the spring 2000 P. minimum bloom on habitat quality for submerged aquatic vegetation (SAV) in the mesohaline region of Chesapeake Bay and its tributaries. We determined the light absorption and scattering spectrum of P. minimum on a per cell basis by analyzing inherent optical properties of natural samples from the Rhode River, Maryland, which were overwhelmingly dominated by P. minimum. Using these per cell properties, we constructed a model of light penetration incorporating observed cell counts of P. minimum to predict the impact of the bloom on other tributaries and main stem locations that experienced the bloom. Model estimates of diffuse attenuation coefficients agreed well with the limited measurements that were available. Impacts of the mahogany tide on diffuse attenuation coefficient ranged from negligible (10-30\\% increase above the seasonal median in the Patapsco and Magothy rivers), to a greater than six-fold increase (Potomac River). Attenuation coefficients in tributaries to the north and south of the bloom region either decreased or were unchanged relative to seasonal medians. Segments with SAV losses in 2000 were mostly the same as those that experienced the P. minimum bloom. Segments north and south of the bloom area mostly had SAV increases in 2000. Though all of the segments that experienced a decline in SAV area after the spring 2000 bloom showed an increase in 2002, the 2000 setback interrupted what otherwise has been a slow recovery in mid-Bay SAV, demonstrating the adverse impact of P. minimum blooms on SAV populations in Chesapeake Bay. © 2004 Elsevier B.V. All rights reserved.},\n\tbooktitle = {Harmful {Algae}},\n\tauthor = {Gallegos, Charles L. and Bergstrom, Peter W.},\n\tyear = {2005},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Extraordinary spring blooms of the dinoflagellate Prorocentrum minimum have been a recurring feature of upper Chesapeake Bay for many years. Though not thought to be toxic in Chesapeake Bay, these blooms produce extraordinarily high concentrations of chlorophyll, thereby increasing light attenuation. A particularly large event occurred in the spring of 2000. Here, we assess the impact of the spring 2000 P. minimum bloom on habitat quality for submerged aquatic vegetation (SAV) in the mesohaline region of Chesapeake Bay and its tributaries. We determined the light absorption and scattering spectrum of P. minimum on a per cell basis by analyzing inherent optical properties of natural samples from the Rhode River, Maryland, which were overwhelmingly dominated by P. minimum. Using these per cell properties, we constructed a model of light penetration incorporating observed cell counts of P. minimum to predict the impact of the bloom on other tributaries and main stem locations that experienced the bloom. Model estimates of diffuse attenuation coefficients agreed well with the limited measurements that were available. Impacts of the mahogany tide on diffuse attenuation coefficient ranged from negligible (10-30% increase above the seasonal median in the Patapsco and Magothy rivers), to a greater than six-fold increase (Potomac River). Attenuation coefficients in tributaries to the north and south of the bloom region either decreased or were unchanged relative to seasonal medians. Segments with SAV losses in 2000 were mostly the same as those that experienced the P. minimum bloom. Segments north and south of the bloom area mostly had SAV increases in 2000. Though all of the segments that experienced a decline in SAV area after the spring 2000 bloom showed an increase in 2002, the 2000 setback interrupted what otherwise has been a slow recovery in mid-Bay SAV, demonstrating the adverse impact of P. minimum blooms on SAV populations in Chesapeake Bay. © 2004 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Eutrophication of Chesapeake Bay: Historical trends and ecological interactions.\n \n \n \n\n\n \n Kemp, W. M.; Boynton, W. R.; Adolf, J. E.; Boesch, D. F.; Boicourt, W. C.; Brush, G.; Cornwell, J. C.; Fisher, T. R.; Glibert, P. M.; Hagy, J. D.; Harding, L. W.; Houde, E. D.; Kimmel, D. G.; Miller, W. D.; Newell, R. I.; Roman, M. R.; Smith, E. M.; and Stevenson, J. C.\n\n\n \n\n\n\n 2005.\n Publication Title: Marine Ecology Progress Series\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{kemp_eutrophication_2005-1,\n\ttitle = {Eutrophication of {Chesapeake} {Bay}: {Historical} trends and ecological interactions},\n\tabstract = {This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in ∼200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared ∼100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macro-infauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay's overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest fundamental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others. © Inter-Research 2005.},\n\tauthor = {Kemp, W. M. and Boynton, W. R. and Adolf, J. E. and Boesch, D. F. and Boicourt, W. C. and Brush, G. and Cornwell, J. C. and Fisher, T. R. and Glibert, P. M. and Hagy, J. D. and Harding, L. W. and Houde, E. D. and Kimmel, D. G. and Miller, W. D. and Newell, R. I.E. and Roman, M. R. and Smith, E. M. and Stevenson, J. C.},\n\tyear = {2005},\n\tdoi = {10.3354/meps303001},\n\tnote = {Publication Title: Marine Ecology Progress Series},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in ∼200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared ∼100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macro-infauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay's overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest fundamental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others. © Inter-Research 2005.\n
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\n \n\n \n \n \n \n \n Chemistry of surface waters: Distinguishing fine-scale differences in sea grass habitats of Chesapeake Bay.\n \n \n \n\n\n \n Dorval, E.; Jones, C. M.; and Hannigan, R.\n\n\n \n\n\n\n Limnology and Oceanography. 2005.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{dorval_chemistry_2005,\n\ttitle = {Chemistry of surface waters: {Distinguishing} fine-scale differences in sea grass habitats of {Chesapeake} {Bay}},\n\tdoi = {10.4319/lo.2005.50.4.1073},\n\tabstract = {We tested the hypothesis that the physical and chemical processes acting in sea grass habitats of the lower Chesapeake Bay are spatially structured and that dissolved elemental chemistry of sea grass-habitat surface waters have their own unique identity. We sampled surface waters from July to September 2001 in five sea grass habitats of the lower bay: Potomac, Rappahannock, York, Island (Tangier-Bloodsworth), and Eastern Shore. Dissolved Mg, Mn, Sr, and Ba concentrations were measured by sector field inductively coupled plasma-mass spectrometry. As expected, Mg, Sr, and Ba exhibited conservative behavior, but Mn exhibited nonconservative behavior along the salinity gradient. Spatial differences in the chemistry of surface waters over sea grass habitats were fully resolvable independently of time. Moreover, classification accuracy of water samples was low in Rappahannock, moderate in Potomac and Eastern Shore, and high in the York and Island habitats. The chemistry of York was distinct because of the effects of physical mixing, whereas Island chemistry was unique, potentially because of the influence of Coriolis acceleration and river discharges from the Susquehanna River. The results of this study show that sites so close to one another in physical space maintain distinct chemical differences. © 2005, by the American Society of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Dorval, Emmanis and Jones, Cynthia M. and Hannigan, Robyn},\n\tyear = {2005},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n We tested the hypothesis that the physical and chemical processes acting in sea grass habitats of the lower Chesapeake Bay are spatially structured and that dissolved elemental chemistry of sea grass-habitat surface waters have their own unique identity. We sampled surface waters from July to September 2001 in five sea grass habitats of the lower bay: Potomac, Rappahannock, York, Island (Tangier-Bloodsworth), and Eastern Shore. Dissolved Mg, Mn, Sr, and Ba concentrations were measured by sector field inductively coupled plasma-mass spectrometry. As expected, Mg, Sr, and Ba exhibited conservative behavior, but Mn exhibited nonconservative behavior along the salinity gradient. Spatial differences in the chemistry of surface waters over sea grass habitats were fully resolvable independently of time. Moreover, classification accuracy of water samples was low in Rappahannock, moderate in Potomac and Eastern Shore, and high in the York and Island habitats. The chemistry of York was distinct because of the effects of physical mixing, whereas Island chemistry was unique, potentially because of the influence of Coriolis acceleration and river discharges from the Susquehanna River. The results of this study show that sites so close to one another in physical space maintain distinct chemical differences. © 2005, by the American Society of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Modeling seagrass density and distribution in response to changes in turbidity stemming from bivalve filtration and seagrass sediment stabilization.\n \n \n \n\n\n \n Newell, R. I.; and Koch, E. W.\n\n\n \n\n\n\n Estuaries. 2004.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{newell_modeling_2004,\n\ttitle = {Modeling seagrass density and distribution in response to changes in turbidity stemming from bivalve filtration and seagrass sediment stabilization},\n\tdoi = {10.1007/BF02912041},\n\tabstract = {In many areas of the North American mid-Atlantic coast, seagrass beds are either in decline or have disappeared due, in part, to high turbidity that reduces the light reaching the plant surface. Because of this reduction in the areal extent of seagrass beds there has been a concomitant diminishment in dampening of water movement (waves and currents) and sediment stabilization. Due to ongoing declines in stocks of suspension-feeding eastern oysters (Crassostrea virginica) in the same region, their feeding activity, which normally serves to improve water clarity, has been sharply reduced. We developed and parameterized a simple model to calculate how changes in the balance between sediment sources (wave-induced resuspension) and sinks (bivalve filtration, sedimentation within seagrass beds) regulate turbidity. Changes in turbidity were used to predict the light available for seagrass photosynthesis and the amount of carbon available for shoot growth. We parameterized this model using published observations and data collected specifically for this purpose. The model predicted that when sediments were resuspended, the presence of even quite modest levels of eastern oysters (25 g dry tissue weight m-2) distributed uniformly throughout the modeled domain, reduced suspended sediment concentrations by nearly an order of magnitude. This increased water clarity, the depth to which seagrasses were predicted to grow. Because hard clams (Mercenaria mercenaria) had a much lower weight-specific filtration rate than eastern oysters; their influence on reducing turbidity was much less than oysters. Seagrasses, once established with sufficiently high densities ({\\textbackslash}textgreater 1,000 shoots m-2), damped waves, thereby reducing sediment resuspension and improving light conditions. This stabilizing effect was minor compared to the influence of uniformly distributed eastern oysters on water clarity. Our model predicted that restoration of eastern oysters has the potential to reduce turbidity in shallow estuaries, such as Chesapeake Bay, and facilitate ongoing efforts to restore seagrasses. This model included several simplifying assumptions, including that oysters were uniformly distributed rather than aggregated into offshore reefs and that oyster feces were not resuspended.},\n\tjournal = {Estuaries},\n\tauthor = {Newell, Roger I.E. and Koch, Evamaria W.},\n\tyear = {2004},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n\n\n
\n In many areas of the North American mid-Atlantic coast, seagrass beds are either in decline or have disappeared due, in part, to high turbidity that reduces the light reaching the plant surface. Because of this reduction in the areal extent of seagrass beds there has been a concomitant diminishment in dampening of water movement (waves and currents) and sediment stabilization. Due to ongoing declines in stocks of suspension-feeding eastern oysters (Crassostrea virginica) in the same region, their feeding activity, which normally serves to improve water clarity, has been sharply reduced. We developed and parameterized a simple model to calculate how changes in the balance between sediment sources (wave-induced resuspension) and sinks (bivalve filtration, sedimentation within seagrass beds) regulate turbidity. Changes in turbidity were used to predict the light available for seagrass photosynthesis and the amount of carbon available for shoot growth. We parameterized this model using published observations and data collected specifically for this purpose. The model predicted that when sediments were resuspended, the presence of even quite modest levels of eastern oysters (25 g dry tissue weight m-2) distributed uniformly throughout the modeled domain, reduced suspended sediment concentrations by nearly an order of magnitude. This increased water clarity, the depth to which seagrasses were predicted to grow. Because hard clams (Mercenaria mercenaria) had a much lower weight-specific filtration rate than eastern oysters; their influence on reducing turbidity was much less than oysters. Seagrasses, once established with sufficiently high densities (\\textgreater 1,000 shoots m-2), damped waves, thereby reducing sediment resuspension and improving light conditions. This stabilizing effect was minor compared to the influence of uniformly distributed eastern oysters on water clarity. Our model predicted that restoration of eastern oysters has the potential to reduce turbidity in shallow estuaries, such as Chesapeake Bay, and facilitate ongoing efforts to restore seagrasses. This model included several simplifying assumptions, including that oysters were uniformly distributed rather than aggregated into offshore reefs and that oyster feces were not resuspended.\n
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\n \n\n \n \n \n \n \n Habitat requirements for submerged aquatic vegetation in Chesapeake Bay: Water quality, light regime, and physical-chemical factors.\n \n \n \n\n\n \n Michael Kemp, W.; Batleson, R.; Bergstrom, P.; Carter, V.; Gallegos, C. L.; Hunley, W.; Karrh, L.; Koch, E. W.; Landwehr, J. M.; Moore, K. A.; Murray, L.; Naylor, M.; Rybicki, N. B.; Court Stevenson, J.; and Wilcox, D. J.\n\n\n \n\n\n\n Estuaries. 2004.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{michael_kemp_habitat_2004,\n\ttitle = {Habitat requirements for submerged aquatic vegetation in {Chesapeake} {Bay}: {Water} quality, light regime, and physical-chemical factors},\n\tdoi = {10.1007/bf02803529},\n\tabstract = {We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing through the water column to the depth of SAV growth (PLW min) and as a percentage of light reaching leaves through the epiphyte layer (PLL min). Values were computed by applying, as inputs to this algorithm, statistically derived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates of PLW min and PLL min compared well with the values established from a literature review. Calculations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophyll a (chl a), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calcu-lated light available at plant leaves exceeded PLL min . Predictions closely matched results of aerial photographic moni-toring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polyhaline regions, which contain 75–80\\% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide.},\n\tjournal = {Estuaries},\n\tauthor = {Michael Kemp, W. and Batleson, Richard and Bergstrom, Peter and Carter, Virginia and Gallegos, Charles L. and Hunley, William and Karrh, Lee and Koch, Evamaria W. and Landwehr, Jurate M. and Moore, Kenneth A. and Murray, Laura and Naylor, Michael and Rybicki, Nancy B. and Court Stevenson, J. and Wilcox, David J.},\n\tyear = {2004},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing through the water column to the depth of SAV growth (PLW min) and as a percentage of light reaching leaves through the epiphyte layer (PLL min). Values were computed by applying, as inputs to this algorithm, statistically derived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates of PLW min and PLL min compared well with the values established from a literature review. Calculations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophyll a (chl a), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calcu-lated light available at plant leaves exceeded PLL min . Predictions closely matched results of aerial photographic moni-toring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polyhaline regions, which contain 75–80% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide.\n
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\n \n\n \n \n \n \n \n Influence of Seagrasses on Water Quality in Shallow Regions of the Lower Chesapeake Bay.\n \n \n \n\n\n \n Moore, K. A.\n\n\n \n\n\n\n Journal of Coastal Research. 2004.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{moore_influence_2004,\n\ttitle = {Influence of {Seagrasses} on {Water} {Quality} in {Shallow} {Regions} of the {Lower} {Chesapeake} {Bay}},\n\tdoi = {10.2112/si45-162.1},\n\tabstract = {Abstract The influence of seagrasses on water quality was investigated seasonally from permanent stations located along transects across vegetated and formerly vegetated sites in shoal regions of the Chesapeake Bay National Estuarine Research Reserve in Virginia. The effect of the seagrass bed on conditions inside compared to outside the bed varied seasonally and could be related to bed biomass and development. During spring (April to June), the rapidly growing seagrass bed was a sink for nutrients, suspended inorganic particles, and phytoplankton, whereas during the summer, as bed dieback progressed, resuspension and release of nutrients were observed. Reductions in suspended particle concentrations and light attenuation were generally not measurable until bed biomass exceeded 50–100 gdm/m2 or 25–50\\% vegetative cover. During April, when nitrate levels in adjacent channel waters were observed to be highest ({\\textbackslash}textgreater10 μM), rapid uptake, equivalent to 48\\% of nitrogen requirements for seagrass growth, reduced inor...},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Moore, Kenneth A.},\n\tyear = {2004},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Abstract The influence of seagrasses on water quality was investigated seasonally from permanent stations located along transects across vegetated and formerly vegetated sites in shoal regions of the Chesapeake Bay National Estuarine Research Reserve in Virginia. The effect of the seagrass bed on conditions inside compared to outside the bed varied seasonally and could be related to bed biomass and development. During spring (April to June), the rapidly growing seagrass bed was a sink for nutrients, suspended inorganic particles, and phytoplankton, whereas during the summer, as bed dieback progressed, resuspension and release of nutrients were observed. Reductions in suspended particle concentrations and light attenuation were generally not measurable until bed biomass exceeded 50–100 gdm/m2 or 25–50% vegetative cover. During April, when nitrate levels in adjacent channel waters were observed to be highest (\\textgreater10 μM), rapid uptake, equivalent to 48% of nitrogen requirements for seagrass growth, reduced inor...\n
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\n \n\n \n \n \n \n \n Periphyton as a UV-B filter on seagrass leaves: A result of different transmittance in the UV-B and PAR ranges.\n \n \n \n\n\n \n Brandt, L. A.; and Koch, E. W.\n\n\n \n\n\n\n Aquatic Botany. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{brandt_periphyton_2003,\n\ttitle = {Periphyton as a {UV}-{B} filter on seagrass leaves: {A} result of different transmittance in the {UV}-{B} and {PAR} ranges},\n\tdoi = {10.1016/S0304-3770(03)00067-6},\n\tabstract = {Periphyton is considered detrimental to seagrasses as it reduces the amount of light, i.e. photosynthetically available radiation (PAR), that reaches the plant surface. This study evaluated the possibility that periphyton can also be beneficial to seagrasses by reducing ultraviolet (UV)-B radiation that reaches seagrass leaves. Periphyton on UV-B transparent artificial leaves transmitted a significantly lower amount of radiation in the UV-B than in the PAR range. Therefore, periphyton is an effective UV-B filter on seagrass leaves. © 2003 Elsevier Science B.V. All rights reserved.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Brandt, Leslie A. and Koch, Evamaria W.},\n\tyear = {2003},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Periphyton is considered detrimental to seagrasses as it reduces the amount of light, i.e. photosynthetically available radiation (PAR), that reaches the plant surface. This study evaluated the possibility that periphyton can also be beneficial to seagrasses by reducing ultraviolet (UV)-B radiation that reaches seagrass leaves. Periphyton on UV-B transparent artificial leaves transmitted a significantly lower amount of radiation in the UV-B than in the PAR range. Therefore, periphyton is an effective UV-B filter on seagrass leaves. © 2003 Elsevier Science B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Interactive Effects of Light and Salinity Stress on the Growth, Reproduction, and Photosynthetic Capabilities of Vallisneria americana (Wild Celery).\n \n \n \n\n\n \n French, G. T.; and Moore, K. A.\n\n\n \n\n\n\n Estuaries. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{french_interactive_2003,\n\ttitle = {Interactive {Effects} of {Light} and {Salinity} {Stress} on the {Growth}, {Reproduction}, and {Photosynthetic} {Capabilities} of {Vallisneria} americana ({Wild} {Celery})},\n\tdoi = {10.1007/BF02803628},\n\tabstract = {The effects of light and salinity on Vallisneria americana (wild celery) were studied in outdoor mesocosms for an entire growing season. Morphology, production, photosynthesis, and reproductive output were monitored from sprouting of winter buds to plant senescence and subsequent winter bud formation under four salinity (0, 5, 10, and 15 psu) and three light (2\\%, 8\\%, and 28\\% of surface irradiance) regimes. Chlorophyll a fluorescence was used to examine photochemical efficiency and relative electron transport rate. High salinity and low light each stunted plant growth and reproduction. Production (biomass, rosette production, and leaf area index) was affected more by salinity than by light, apparently because of morphological plasticity (increased leaf length and width), increased photosynthetic efficiency, and increased chlorophyll concentrations under low light. Relative maximum electron transport rate (ETRmax) was highest in the 28\\% light treatment, indicating increased photosynthetic capacity. ETRmax was not related to salinity, suggesting that the detrimental effects of salinity on production were through decreased photochemical efficiency and not decreased photosynthetic capacity. Light and salinity effects were interactive for measures of production, with negative salinity effects most apparent under high light conditions, and light effects found primarily at low salinity levels. For most production and morphology parameters, high light ameliorated salinity stress to a limited degree, but only between the 0 and 5 psu regimes. Growth was generally minimal in all of the 10 and 15 psu treatments, regardless of light level. Growth was also greatly reduced at 2\\% and 8\\% light. Flowering and winter bud production were impaired at 10 and 15 psu and at 2\\% and 8\\% light. Light requirements at 5 psu may be approximately 50\\% higher than at 0 psu. Because of the interaction between salinity and light requirements for growth, effective management of SAV requires that growth requirements incorporate the effects of combined stressors.},\n\tjournal = {Estuaries},\n\tauthor = {French, Gail T. and Moore, Kenneth A.},\n\tyear = {2003},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The effects of light and salinity on Vallisneria americana (wild celery) were studied in outdoor mesocosms for an entire growing season. Morphology, production, photosynthesis, and reproductive output were monitored from sprouting of winter buds to plant senescence and subsequent winter bud formation under four salinity (0, 5, 10, and 15 psu) and three light (2%, 8%, and 28% of surface irradiance) regimes. Chlorophyll a fluorescence was used to examine photochemical efficiency and relative electron transport rate. High salinity and low light each stunted plant growth and reproduction. Production (biomass, rosette production, and leaf area index) was affected more by salinity than by light, apparently because of morphological plasticity (increased leaf length and width), increased photosynthetic efficiency, and increased chlorophyll concentrations under low light. Relative maximum electron transport rate (ETRmax) was highest in the 28% light treatment, indicating increased photosynthetic capacity. ETRmax was not related to salinity, suggesting that the detrimental effects of salinity on production were through decreased photochemical efficiency and not decreased photosynthetic capacity. Light and salinity effects were interactive for measures of production, with negative salinity effects most apparent under high light conditions, and light effects found primarily at low salinity levels. For most production and morphology parameters, high light ameliorated salinity stress to a limited degree, but only between the 0 and 5 psu regimes. Growth was generally minimal in all of the 10 and 15 psu treatments, regardless of light level. Growth was also greatly reduced at 2% and 8% light. Flowering and winter bud production were impaired at 10 and 15 psu and at 2% and 8% light. Light requirements at 5 psu may be approximately 50% higher than at 0 psu. Because of the interaction between salinity and light requirements for growth, effective management of SAV requires that growth requirements incorporate the effects of combined stressors.\n
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\n \n\n \n \n \n \n \n Multiscale Experiments in Coastal Ecology: Improving Realism and Advancing Theory.\n \n \n \n\n\n \n PETERSEN, J. E.; KEMP, W. M.; BARTLESON, R.; BOYNTON, W. R.; CHEN, C.; CORNWELL, J. C.; GARDNER, R. H.; HINKLE, D. C.; HOUDE, E. D.; MALONE, T. C.; MOWITT, W. P.; MURRAY, L.; SANFORD, L. P.; STEVENSON, J. C.; SUNDBERG, K. L.; and SUTTLES, S. E.\n\n\n \n\n\n\n BioScience. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{petersen_multiscale_2003,\n\ttitle = {Multiscale {Experiments} in {Coastal} {Ecology}: {Improving} {Realism} and {Advancing} {Theory}},\n\tdoi = {10.1641/0006-3568(2003)053[1181:meicei]2.0.co;2},\n\tabstract = {The Multiscale Experimental Ecosystem Research Center has conducted a series of mesocosm experiments to quantify the effects of scale - in terms of time, depth, radius, exchange rate, and ecological complexity - on biogeochemical processes and trophic dynamics in a variety of coastal habitats. The results indicate that scale effects can be categorized as (a) fundamental effects, which are evident in both natural and experimental ecosystems, and (b) artifacts of enclosure, which are solely attributable to the artificial environment in mesocosms. We conclude that multiscale experiments increase researchers' understanding of scale in nature and improve their ability to design scale-sensitive experiments, the results of which can be systematically compared with each other and extrapolated to nature.},\n\tjournal = {BioScience},\n\tauthor = {PETERSEN, JOHN E. and KEMP, W. MICHAEL and BARTLESON, RICK and BOYNTON, WALTER R. and CHEN, CHUNG-CHI and CORNWELL, JEFFREY C. and GARDNER, ROBERT H. and HINKLE, DEBORAH C. and HOUDE, EDWARD D. and MALONE, THOMAS C. and MOWITT, WILLIAM P. and MURRAY, LAURA and SANFORD, LAWRENCE P. and STEVENSON, J. COURT and SUNDBERG, KAREN L. and SUTTLES, STEVE E.},\n\tyear = {2003},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The Multiscale Experimental Ecosystem Research Center has conducted a series of mesocosm experiments to quantify the effects of scale - in terms of time, depth, radius, exchange rate, and ecological complexity - on biogeochemical processes and trophic dynamics in a variety of coastal habitats. The results indicate that scale effects can be categorized as (a) fundamental effects, which are evident in both natural and experimental ecosystems, and (b) artifacts of enclosure, which are solely attributable to the artificial environment in mesocosms. We conclude that multiscale experiments increase researchers' understanding of scale in nature and improve their ability to design scale-sensitive experiments, the results of which can be systematically compared with each other and extrapolated to nature.\n
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\n \n\n \n \n \n \n \n Long-distance dispersal potential in a marine macrophyte.\n \n \n \n\n\n \n Harwell, M. C.; and Orth, R. J.\n\n\n \n\n\n\n Ecology. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{harwell_long-distance_2002,\n\ttitle = {Long-distance dispersal potential in a marine macrophyte},\n\tdoi = {10.1890/0012-9658(2002)083[3319:LDDPIA]2.0.CO;2},\n\tabstract = {Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.},\n\tjournal = {Ecology},\n\tauthor = {Harwell, Matthew C. and Orth, Robert J.},\n\tyear = {2002},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.\n
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\n \n\n \n \n \n \n \n Operation of the xanthophyll cycle in the seagrass Zostera marina in response to variable irradiance.\n \n \n \n\n\n \n Ralph, P. J.; Polk, S. M.; Moore, K. A.; Orth, R. J.; and Smith, W. O.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{ralph_operation_2002,\n\ttitle = {Operation of the xanthophyll cycle in the seagrass {Zostera} marina in response to variable irradiance},\n\tdoi = {10.1016/S0022-0981(02)00047-3},\n\tabstract = {Changes in the photobiology and photosynthetic pigments of the seagrass Zostera marina from Chesapeake Bay (USA) were examined under a range of natural and manipulated irradiance regimes. Photosynthetic activity was assessed using chlorophyll-a fluorescence, and photosynthetic pigments were measured by HPLC. Large changes in the violaxanthin, zeaxanthin, and antheraxanthin content were concomitant with the modulation of non-photochemical quenching (NPQ). Photokinetics (Fv/Fm, rapid light curves (RLC), and non-photochemical quenching) varied as a result of oscillating irradiance and were highly correlated to xanthophyll pigment content. Zeaxanthin and antheraxanthin concentrations increased under elevated light conditions, while violaxanthin increased in darkened conditions. Unusually high concentrations of antheraxanthin were found in Z. marina under a wide range of light conditions, and this was associated with the partial conversion of violaxanthin to zeaxanthin. These results support the idea that xanthophyll intermediate pigments induce a photoprotective response during exposure to high irradiances in this seagrass. © 2002 Elsevier Science B.V. All rights reserved.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Ralph, P. J. and Polk, S. M. and Moore, K. A. and Orth, R. J. and Smith, W. O.},\n\tyear = {2002},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Changes in the photobiology and photosynthetic pigments of the seagrass Zostera marina from Chesapeake Bay (USA) were examined under a range of natural and manipulated irradiance regimes. Photosynthetic activity was assessed using chlorophyll-a fluorescence, and photosynthetic pigments were measured by HPLC. Large changes in the violaxanthin, zeaxanthin, and antheraxanthin content were concomitant with the modulation of non-photochemical quenching (NPQ). Photokinetics (Fv/Fm, rapid light curves (RLC), and non-photochemical quenching) varied as a result of oscillating irradiance and were highly correlated to xanthophyll pigment content. Zeaxanthin and antheraxanthin concentrations increased under elevated light conditions, while violaxanthin increased in darkened conditions. Unusually high concentrations of antheraxanthin were found in Z. marina under a wide range of light conditions, and this was associated with the partial conversion of violaxanthin to zeaxanthin. These results support the idea that xanthophyll intermediate pigments induce a photoprotective response during exposure to high irradiances in this seagrass. © 2002 Elsevier Science B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Light and temperature effects on the growth of wild celery and hydrilla.\n \n \n \n\n\n \n Rybicki, N. B.; and Carter, V.\n\n\n \n\n\n\n Journal of Aquatic Plant Management. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{rybicki_light_2002,\n\ttitle = {Light and temperature effects on the growth of wild celery and hydrilla},\n\tabstract = {Wild celery (Vallisneria americana L.) has coexisted with the dominant species hydrilla (Hydrilla verticillata (L.f.) Royle) since the resurgence of submersed aquatic vegetation in the tidal Potomac River in 1983. In 1989, particularly turbid, cool, and cloudy spring conditions were associated with a substantial decrease in hydrilla coverage. We measured growth and elongation potential of wild celery and hydrilla propagules under various temperature and irradiance conditions to compare these two species and in part explain the stable persistence of wild celery and the variability in hydrilla coverage. A plant growth experiment was conducted to simulate actual temperatures in the Potomac River during spring of 1986 (plant coverage increased) and 1989 (plant coverage decreased). In the 1989 temperature treatment, final heights of hydrilla and wild celery were unaffected by a 6-C decrease in temperature 2 weeks following tuber germination. Heights of wild celery, however, were more than twice that of hydrilla, and elongation rates of wild celery were greater than those of hydrilla when temperatures reached 17 to 22C. Laboratory studies conducted in complete darkness showed that wild celery tubers germinate at 13C, whereas hydrilla tubers germinate at 15C, and that wild celery elongated to heights twice those of hydrilla. Heights were positively correlated to tuber length. If irradiance is diminished at incipience, differences in tuber reserves and elongation potential may be sufficient to ensure that wild celery can survive when hydrilla is not successful.},\n\tjournal = {Journal of Aquatic Plant Management},\n\tauthor = {Rybicki, Nancy B. and Carter, Virginia},\n\tyear = {2002},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Wild celery (Vallisneria americana L.) has coexisted with the dominant species hydrilla (Hydrilla verticillata (L.f.) Royle) since the resurgence of submersed aquatic vegetation in the tidal Potomac River in 1983. In 1989, particularly turbid, cool, and cloudy spring conditions were associated with a substantial decrease in hydrilla coverage. We measured growth and elongation potential of wild celery and hydrilla propagules under various temperature and irradiance conditions to compare these two species and in part explain the stable persistence of wild celery and the variability in hydrilla coverage. A plant growth experiment was conducted to simulate actual temperatures in the Potomac River during spring of 1986 (plant coverage increased) and 1989 (plant coverage decreased). In the 1989 temperature treatment, final heights of hydrilla and wild celery were unaffected by a 6-C decrease in temperature 2 weeks following tuber germination. Heights of wild celery, however, were more than twice that of hydrilla, and elongation rates of wild celery were greater than those of hydrilla when temperatures reached 17 to 22C. Laboratory studies conducted in complete darkness showed that wild celery tubers germinate at 13C, whereas hydrilla tubers germinate at 15C, and that wild celery elongated to heights twice those of hydrilla. Heights were positively correlated to tuber length. If irradiance is diminished at incipience, differences in tuber reserves and elongation potential may be sufficient to ensure that wild celery can survive when hydrilla is not successful.\n
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\n \n\n \n \n \n \n \n Beyond light: Physical, geological, and geochemical parameters as possible submersed aquatic vegetation habitat requirements.\n \n \n \n\n\n \n Koch, E. W.\n\n\n \n\n\n\n 2001.\n Publication Title: Estuaries\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{koch_beyond_2001,\n\ttitle = {Beyond light: {Physical}, geological, and geochemical parameters as possible submersed aquatic vegetation habitat requirements},\n\tabstract = {When determining the suitability of a certain area as a habitat for submersed aquatic vegetation (SAV), light and parameters that modify light (epiphytes, total suspended solids, chlorophyll concentration, nutrients) are the first factors to be taken into consideration. As a result, in the past 10 years, light has been the major focus of SAV research. Even so, we are still unable to explain why SAV often occurs in one area but is absent just a few meters away. Recent studies have shown that SAV may not occur in areas where light levels are adequate but other parameters like wave energy and sulfide concentrations are excessive. It is time to look beyond light when determining SAV habitat requirements. This paper summarizes the impact that physical (waves, currents, tides, and turbulence), geological (sediment grain size and organic matter), and geochemical (mainly sulfide) parameters may have on SAV habitat suitability. Light remains an integral part of the discussion but the focus shifts from maximum depths of distribution (determined mainly by light) to the range SAV can colonize between the maximum and minimum depths of distribution (determined mainly by physical forces). This paper establishes minimum depths of occurrence resulting from the effects of tides and waves, preferred ranges in particle size, organic content, and sulfide, as well as limits on currents and waves as related to the capacity to stay rooted at one extreme and diffusive boundary layer constrains at the other.},\n\tauthor = {Koch, E. W.},\n\tyear = {2001},\n\tdoi = {10.2307/1352808},\n\tnote = {Publication Title: Estuaries},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n When determining the suitability of a certain area as a habitat for submersed aquatic vegetation (SAV), light and parameters that modify light (epiphytes, total suspended solids, chlorophyll concentration, nutrients) are the first factors to be taken into consideration. As a result, in the past 10 years, light has been the major focus of SAV research. Even so, we are still unable to explain why SAV often occurs in one area but is absent just a few meters away. Recent studies have shown that SAV may not occur in areas where light levels are adequate but other parameters like wave energy and sulfide concentrations are excessive. It is time to look beyond light when determining SAV habitat requirements. This paper summarizes the impact that physical (waves, currents, tides, and turbulence), geological (sediment grain size and organic matter), and geochemical (mainly sulfide) parameters may have on SAV habitat suitability. Light remains an integral part of the discussion but the focus shifts from maximum depths of distribution (determined mainly by light) to the range SAV can colonize between the maximum and minimum depths of distribution (determined mainly by physical forces). This paper establishes minimum depths of occurrence resulting from the effects of tides and waves, preferred ranges in particle size, organic content, and sulfide, as well as limits on currents and waves as related to the capacity to stay rooted at one extreme and diffusive boundary layer constrains at the other.\n
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\n \n\n \n \n \n \n \n Calculating optical water quality targets to restore and protect submersed aquatic vegetation: Overcoming problems in partitioning the diffuse attenuation coefficient for photosynthetically active radiation.\n \n \n \n\n\n \n Gallegos, C. L.\n\n\n \n\n\n\n Estuaries. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{gallegos_calculating_2001,\n\ttitle = {Calculating optical water quality targets to restore and protect submersed aquatic vegetation: {Overcoming} problems in partitioning the diffuse attenuation coefficient for photosynthetically active radiation},\n\tdoi = {10.2307/1353240},\n\tabstract = {Submersed aquatic vegetation (SAV) is an important component of shallow water estuarine systems that has declined drastically in recent decades. SAV has particularly high light requirements, and losses of SAV have, in many cases, been attributed to increased light attenuation in the water column, frequently due to coastal eutrophication. The desire to restore these valuable habitats to their historical levels has created the need for a simple but accurate management tool for translating light requirements into water quality targets capable of supporting SAV communities. A procedure for calculating water quality targets for concentrations of chlorophyll and total suspended solids (TSS) is derived, based on representing the diffuse attenuation coefficient for photosynthetically active radiation, Kd(PAR), as a linear function of contributions due to water plus colored dissolved organic matter (CDOM), chlorophyll, and TSS. It is assumed that Kd(PAR) conforms to the Lambert-Beer law. Target concentrations are determined as the intersection of a line representing intended reduction of TSS and chlorophyll by management actions, with another line describing the dependence of TSS on chlorophyll at a constant value of Kd(PAR). The validity of applying the Lambert-Beer law to Kd(PAR) in estuarine waters was tested by comparing the performance of a linear model of Kd(PAR) with data simulated using a more realistic model of light attenuation. The linear regression model tended to underestimate Kd(PAR) at high light attenuation, resulting in erroneous predictions of target concentrations at shallow restoration depths. The errors result more from the wide spectral bandwidth of PAR, than from irrecoverable nonlinearities in the diffuse attenuation coefficient per se. In spite of the failure of the Lambert-Beer law applied to Kd(PAR), the variation of TSS with chlorophyll at constant Kd(PAR) determined by the more mechanistic attenuation model was, nevertheless, highly linear. Use of the management tool based on intersecting lines is still possible, but coefficients in the line describing the dependence of TSS on chlorophyll at constant Kdd(PAR) must be determined empirically by application of an optical model suitably calibrated for the region of interest. An example application of the procedure to data from the Rhode River, Maryland, indicates that approximately 15\\% reduction in both TSS and chlorophyll concentrations, or 50\\% reduction in chlorophyll alone, will be needed to restore conditions for growth of SAV to levels that existed in the late 1960s.},\n\tjournal = {Estuaries},\n\tauthor = {Gallegos, C. L.},\n\tyear = {2001},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Submersed aquatic vegetation (SAV) is an important component of shallow water estuarine systems that has declined drastically in recent decades. SAV has particularly high light requirements, and losses of SAV have, in many cases, been attributed to increased light attenuation in the water column, frequently due to coastal eutrophication. The desire to restore these valuable habitats to their historical levels has created the need for a simple but accurate management tool for translating light requirements into water quality targets capable of supporting SAV communities. A procedure for calculating water quality targets for concentrations of chlorophyll and total suspended solids (TSS) is derived, based on representing the diffuse attenuation coefficient for photosynthetically active radiation, Kd(PAR), as a linear function of contributions due to water plus colored dissolved organic matter (CDOM), chlorophyll, and TSS. It is assumed that Kd(PAR) conforms to the Lambert-Beer law. Target concentrations are determined as the intersection of a line representing intended reduction of TSS and chlorophyll by management actions, with another line describing the dependence of TSS on chlorophyll at a constant value of Kd(PAR). The validity of applying the Lambert-Beer law to Kd(PAR) in estuarine waters was tested by comparing the performance of a linear model of Kd(PAR) with data simulated using a more realistic model of light attenuation. The linear regression model tended to underestimate Kd(PAR) at high light attenuation, resulting in erroneous predictions of target concentrations at shallow restoration depths. The errors result more from the wide spectral bandwidth of PAR, than from irrecoverable nonlinearities in the diffuse attenuation coefficient per se. In spite of the failure of the Lambert-Beer law applied to Kd(PAR), the variation of TSS with chlorophyll at constant Kd(PAR) determined by the more mechanistic attenuation model was, nevertheless, highly linear. Use of the management tool based on intersecting lines is still possible, but coefficients in the line describing the dependence of TSS on chlorophyll at constant Kdd(PAR) must be determined empirically by application of an optical model suitably calibrated for the region of interest. An example application of the procedure to data from the Rhode River, Maryland, indicates that approximately 15% reduction in both TSS and chlorophyll concentrations, or 50% reduction in chlorophyll alone, will be needed to restore conditions for growth of SAV to levels that existed in the late 1960s.\n
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\n \n\n \n \n \n \n \n System-wide submerged aquatic vegetation model for Chesapeake Bay.\n \n \n \n\n\n \n Cerco, C. F.; and Moore, K.\n\n\n \n\n\n\n Estuaries. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{cerco_system-wide_2001,\n\ttitle = {System-wide submerged aquatic vegetation model for {Chesapeake} {Bay}},\n\tdoi = {10.2307/1353254},\n\tabstract = {A predictive model of submerged aquatic vegetation (SAV) biomass is coupled to a eutrophication model of Chesapeake Bay. Domain of the model includes the mainstem of the bay as well as tidal portions of major embayments and tributaries. Three SAV communities are modeled: ZOSTERA, RUPPIA, and FRESHWATER. The model successfully computes the spatial distribution and abundance of SAV for the period 1985-1994. Spatial distribution is primarily determined by computed light attenuation. Sensitivity analysis to reductions in nutrient and solids loads indicates nutrient controls will enhance abundance primarily in areas that presently support SAV. Restoration of SAV to areas in which it does not presently exist requires solids controls, alone or in combination with nutrient controls. For regions in which SAV populations exist at the refuge level or greater, improvements in SAV abundance are expected within 2 to 10 years of load reductions. For regions in which no refuge population exists, recovery time is unpredictable and will depend on propagule supply.},\n\tjournal = {Estuaries},\n\tauthor = {Cerco, Carl F. and Moore, Kenneth},\n\tyear = {2001},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n\n\n
\n A predictive model of submerged aquatic vegetation (SAV) biomass is coupled to a eutrophication model of Chesapeake Bay. Domain of the model includes the mainstem of the bay as well as tidal portions of major embayments and tributaries. Three SAV communities are modeled: ZOSTERA, RUPPIA, and FRESHWATER. The model successfully computes the spatial distribution and abundance of SAV for the period 1985-1994. Spatial distribution is primarily determined by computed light attenuation. Sensitivity analysis to reductions in nutrient and solids loads indicates nutrient controls will enhance abundance primarily in areas that presently support SAV. Restoration of SAV to areas in which it does not presently exist requires solids controls, alone or in combination with nutrient controls. For regions in which SAV populations exist at the refuge level or greater, improvements in SAV abundance are expected within 2 to 10 years of load reductions. For regions in which no refuge population exists, recovery time is unpredictable and will depend on propagule supply.\n
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\n \n\n \n \n \n \n \n Seasonal variations in eelgrass (Zostera marina L.) responses to nutrient enrichment and reduced light availability in experimental ecosystems.\n \n \n \n\n\n \n Moore, K. A.; and Wetzel, R. L.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 2000.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_seasonal_2000,\n\ttitle = {Seasonal variations in eelgrass ({Zostera} marina {L}.) responses to nutrient enrichment and reduced light availability in experimental ecosystems},\n\tdoi = {10.1016/S0022-0981(99)00135-5},\n\tabstract = {The single and interactive effects of altered water column nutrient concentrations and light availability on the growth of the seagrass Zostera marina L. (eelgrass) and its attached epiphytes were investigated in 110 liter microcosms. Experiments lasting 4 to 6 weeks were conducted seasonally during spring, summer and fall in a greenhouse equipped with flow-through seawater from the adjacent York River estuary of the Chesapeake Bay. Nutrient treatments consisted of inflow seawater with ambient or enriched (2 x to 3 x) concentrations of dissolved inorganic nitrogen and phosphorus and with rapid turnover (16 d-1). Enrichment levels were chosen to evaluate conditions found in regions of the Chesapeake Bay where Z. marina has declined. Light reductions were accomplished by shading individual microcosms with neutral density screening so that mean scalar irradiance was 42, 28, or 9\\% of solar PAR. These levels were chosen to simulate light reductions observed along gradients of turbidity which characterize present and former Z. marina habitats in the region. Epiphytic grazers consisted of gastropods (Bittium varium and Mittella lunata) which were applied at consistent densities (5200 m-2) for all experiments. Growth of both the seagrasses and their associated epiphytes decreased with increased shading. There was little additional response to nutrient enrichment except at highest light levels during the spring when macroepiphytes increased to over 10 x the seagrass mass and seagrass growth decreased. The results suggest that it is principally light availability which governs seagrass growth in moderately nutrient enriched regions of the bay. In systems such as the York River, given adequate grazer densities, observed levels of nutrient enrichment are unlikely to cause excessive epiphyte loads and subsequent seagrass declines. Although Z. marina tissue levels of nitrogen and phosphorus increased significantly with enrichment and with shading no direct effects of nitrate toxicity were observed.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Moore, Kenneth A. and Wetzel, Richard L.},\n\tyear = {2000},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n The single and interactive effects of altered water column nutrient concentrations and light availability on the growth of the seagrass Zostera marina L. (eelgrass) and its attached epiphytes were investigated in 110 liter microcosms. Experiments lasting 4 to 6 weeks were conducted seasonally during spring, summer and fall in a greenhouse equipped with flow-through seawater from the adjacent York River estuary of the Chesapeake Bay. Nutrient treatments consisted of inflow seawater with ambient or enriched (2 x to 3 x) concentrations of dissolved inorganic nitrogen and phosphorus and with rapid turnover (16 d-1). Enrichment levels were chosen to evaluate conditions found in regions of the Chesapeake Bay where Z. marina has declined. Light reductions were accomplished by shading individual microcosms with neutral density screening so that mean scalar irradiance was 42, 28, or 9% of solar PAR. These levels were chosen to simulate light reductions observed along gradients of turbidity which characterize present and former Z. marina habitats in the region. Epiphytic grazers consisted of gastropods (Bittium varium and Mittella lunata) which were applied at consistent densities (5200 m-2) for all experiments. Growth of both the seagrasses and their associated epiphytes decreased with increased shading. There was little additional response to nutrient enrichment except at highest light levels during the spring when macroepiphytes increased to over 10 x the seagrass mass and seagrass growth decreased. The results suggest that it is principally light availability which governs seagrass growth in moderately nutrient enriched regions of the bay. In systems such as the York River, given adequate grazer densities, observed levels of nutrient enrichment are unlikely to cause excessive epiphyte loads and subsequent seagrass declines. Although Z. marina tissue levels of nitrogen and phosphorus increased significantly with enrichment and with shading no direct effects of nitrate toxicity were observed.\n
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\n \n\n \n \n \n \n \n A linked physical and biological framework to assess biogeochemical dynamics in a shallow estuarine ecosystem.\n \n \n \n\n\n \n Buzzelli, C. P.; Wetzel, R. L.; and Meyers, M. B.\n\n\n \n\n\n\n Estuarine, Coastal and Shelf Science. 1999.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{buzzelli_linked_1999,\n\ttitle = {A linked physical and biological framework to assess biogeochemical dynamics in a shallow estuarine ecosystem},\n\tdoi = {10.1006/ecss.1999.0556},\n\tabstract = {the littoral zone of Chesapeake Bay contains a mosaic of shallow vegetated and nonvegetated habitats with biotic components that are sensitive to changes in biological and physical driving factors. Static and dynamic modelling frameworks provide an integrative way to study complex hydrodynamic and biogeochemical processes in linked estuarine habitats. In this study we describe a spatial simulation model developed and calibrated relative to a specific littoral zone, estuarine ecosystem. The model consisted of four distinct habitats that contained phytoplankton, sediment microalgae, Zostera marina (eelgrass, and Spartina alterniflora. There was tidal exchange of phytoplankton, particulate and dissolved organic carbon and dissolved inorganic nitrogen between the littoral zone ecosystem and the offshore channel. Physical exchange and biogeochemical transformations within the habitats determined water column concentrations and Z. marina and S. alterniflora biomass were within the variability of validation data and the predicted annual rates of net primary production were similar to measured rates. Phytoplankton accounted for 17\\%, sediment microalgae 46\\%, the Z. marina community 24\\% and S. alterniflora 13\\% the annual littoral zone primary production. The linked habitat model provided insights into producer, habitat and ecosystem carbon and nitrogen properties that might not have been evident with stand-alone models. Although it was an intra-ecosystem sink for particulate carbon, the seagrass habitat was a DOC source and responsible for over 30\\% of the littoral zone carbon and nitrogen primary production. The model predicted that the Goodwin Islands littoral zone was a sink of channel derived POC, but a source of DOC to the surrounding estuary. The framework created in this study of estuarine ecosystem dynamics is applicable to many different aquatic systems over a range of spatial and temporal scales.},\n\tjournal = {Estuarine, Coastal and Shelf Science},\n\tauthor = {Buzzelli, C. P. and Wetzel, R. L. and Meyers, M. B.},\n\tyear = {1999},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n the littoral zone of Chesapeake Bay contains a mosaic of shallow vegetated and nonvegetated habitats with biotic components that are sensitive to changes in biological and physical driving factors. Static and dynamic modelling frameworks provide an integrative way to study complex hydrodynamic and biogeochemical processes in linked estuarine habitats. In this study we describe a spatial simulation model developed and calibrated relative to a specific littoral zone, estuarine ecosystem. The model consisted of four distinct habitats that contained phytoplankton, sediment microalgae, Zostera marina (eelgrass, and Spartina alterniflora. There was tidal exchange of phytoplankton, particulate and dissolved organic carbon and dissolved inorganic nitrogen between the littoral zone ecosystem and the offshore channel. Physical exchange and biogeochemical transformations within the habitats determined water column concentrations and Z. marina and S. alterniflora biomass were within the variability of validation data and the predicted annual rates of net primary production were similar to measured rates. Phytoplankton accounted for 17%, sediment microalgae 46%, the Z. marina community 24% and S. alterniflora 13% the annual littoral zone primary production. The linked habitat model provided insights into producer, habitat and ecosystem carbon and nitrogen properties that might not have been evident with stand-alone models. Although it was an intra-ecosystem sink for particulate carbon, the seagrass habitat was a DOC source and responsible for over 30% of the littoral zone carbon and nitrogen primary production. The model predicted that the Goodwin Islands littoral zone was a sink of channel derived POC, but a source of DOC to the surrounding estuary. The framework created in this study of estuarine ecosystem dynamics is applicable to many different aquatic systems over a range of spatial and temporal scales.\n
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\n \n\n \n \n \n \n \n Scaling submersed plant community responses to experimental nutrient enrichment.\n \n \n \n\n\n \n Murray, L.; Brian Sturgis, R.; Bartleson, R. D.; Severn, W.; and Michael Kemp, W.\n\n\n \n\n\n\n In Seagrasses: Monitoring, Ecology, Physiology, and Management. 1999.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@incollection{murray_scaling_1999,\n\ttitle = {Scaling submersed plant community responses to experimental nutrient enrichment},\n\tisbn = {978-1-4200-7447-5},\n\tabstract = {Detailed mechanistic understanding of how nutrient enrichment leads to losses of seagrasses and related submerged aquatic vegetation (SAV) is still lacking, despite extensive research on the topic. In this study, we compare results from a series of three mesocosm experiments to address how physical and biotic scales influence responses of SAV communities to nutrient enrichment. These experiments, which involved the SAV species (Potamogeton perfoliatus) formerly abundant in Chesapeake Bay, considered the following specific ecosystem scales: (1) frequency and timing of nutrient additions; (2) residence time of water within mesocosms; and (3) trophic complexity (food-chain length). Ecosystem model simulations were used to help guide experimental designs and interpretations. Time scales of response to nutrient enrichment differed for SAV (8-9 wk) and their attached epiphytes (2-6 wk). SAV growth responses to nutrients varied with season; in spring the aboveground plant tissues were most sensitive, while in fall responses were confined to below-ground biomass (roots and rhizomes). In the fall experiment, continuous nutrient input resulted in greater enhancement of epiphytes and inhibition of plant growth than did identical loading rates delivered as pulsed inputs. This may be explained by the higher biomass and kinetic saturation coefficients of the vascular plants, which favored their uptake of higher pulsed nutrient concentrations. In general, longer residence time of water over SAV beds improved the plant's ability to cope with nutrient enrichment, while faster water exchange rates favored epiphyte growth at the expense of SAV. Although herbivorous grazing on epiphytes partially relieved SAV growth inhibition at moderate nutrient loading, grazing did not significantly alter epiphyte or plant responses to enrichment at higher nutrient levels. A comparison of effects of the three scaling factors suggests that grazing exerted the largest relative influence on the SAV community under moderate nutrient enrichment. However, at high nutrient loading rates, changes from continuous to pulsed nutrient delivery and from high to low water exchange rates both resulted in stronger relative responses than did increased grazing. Results of these studies provide a basis for explaining variability in reported SAV community responses to nutrient enrichment and for extrapolating results from controlled experiments to conditions in nature.},\n\tbooktitle = {Seagrasses: {Monitoring}, {Ecology}, {Physiology}, and {Management}},\n\tauthor = {Murray, Laura and Brian Sturgis, R. and Bartleson, Richard D. and Severn, William and Michael Kemp, W.},\n\tyear = {1999},\n\tdoi = {10.1201/9781420074475},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
\n\n\n
\n Detailed mechanistic understanding of how nutrient enrichment leads to losses of seagrasses and related submerged aquatic vegetation (SAV) is still lacking, despite extensive research on the topic. In this study, we compare results from a series of three mesocosm experiments to address how physical and biotic scales influence responses of SAV communities to nutrient enrichment. These experiments, which involved the SAV species (Potamogeton perfoliatus) formerly abundant in Chesapeake Bay, considered the following specific ecosystem scales: (1) frequency and timing of nutrient additions; (2) residence time of water within mesocosms; and (3) trophic complexity (food-chain length). Ecosystem model simulations were used to help guide experimental designs and interpretations. Time scales of response to nutrient enrichment differed for SAV (8-9 wk) and their attached epiphytes (2-6 wk). SAV growth responses to nutrients varied with season; in spring the aboveground plant tissues were most sensitive, while in fall responses were confined to below-ground biomass (roots and rhizomes). In the fall experiment, continuous nutrient input resulted in greater enhancement of epiphytes and inhibition of plant growth than did identical loading rates delivered as pulsed inputs. This may be explained by the higher biomass and kinetic saturation coefficients of the vascular plants, which favored their uptake of higher pulsed nutrient concentrations. In general, longer residence time of water over SAV beds improved the plant's ability to cope with nutrient enrichment, while faster water exchange rates favored epiphyte growth at the expense of SAV. Although herbivorous grazing on epiphytes partially relieved SAV growth inhibition at moderate nutrient loading, grazing did not significantly alter epiphyte or plant responses to enrichment at higher nutrient levels. A comparison of effects of the three scaling factors suggests that grazing exerted the largest relative influence on the SAV community under moderate nutrient enrichment. However, at high nutrient loading rates, changes from continuous to pulsed nutrient delivery and from high to low water exchange rates both resulted in stronger relative responses than did increased grazing. Results of these studies provide a basis for explaining variability in reported SAV community responses to nutrient enrichment and for extrapolating results from controlled experiments to conditions in nature.\n
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\n \n\n \n \n \n \n \n Dynamic simulation of littoral zone habitats in lower Chesapeake Bay. I. Ecosystem characterization related to model development.\n \n \n \n\n\n \n Buzzelli, C. P.\n\n\n \n\n\n\n Estuaries. 1998.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{buzzelli_dynamic_1998-1,\n\ttitle = {Dynamic simulation of littoral zone habitats in lower {Chesapeake} {Bay}. {I}. {Ecosystem} characterization related to model development},\n\tdoi = {10.2307/1353271},\n\tabstract = {The fringing environments of lower Chesapeake Bay include sandy shoals, seagrass meadows, intertidal mud flats, and marshes. A characterization of a fringing ecosystem was conducted to provide initialization and calibration data for the development of a simulation model. The model simulates primary production and material exchange in the littoral zone of lower Chesapeake Bay. Carbon (C) and nitrogen (N) properties of water and sediments from sand, seagrass, intertidal silt-mud, and intertidal marsh habitats of the Goodwin Island (located within the Chesapeake Bay National Estuarine Research Reserve in Virginia, CBNERR-VA) were determined seasonally. Spatial and temporal differences in sediment microalgal biomass among the habitats were assessed along with annual variations in the distribution and abundance of Zostera marina L. and Spartina alterniflora Loisel. Phytoplankton biomass displayed some seasonality related to riverine discharge, but sediment microalgal biomass did not vary spatially or seasonally. Macrophytes in both subtidal and intertidal habitats exhibited seasonal biomass patterns that were consistent with other Atlantic estuarine ecosystems. Marsh sediment organic carbon and inorganic nitrogen differed significantly from that of the sand, seagrass, and silt habitats. The only biogeochemical variable that exhibited seasonality was low marsh NH4+. The subtidal sediments were consistent temporally in their carbon and nitrogen content despite seasonal changes in seagrass abundance. Eelgrass has a comparatively low C:N ratio and is a potential N sink for the ecosystem. Changes in the composition or size of the vegetated habitats could have a dramatic influence over resource partitioning within the ecosystem. A spatial database (or geographic information system, GIS) of the Goodwin Islands site has been initiated to track long-term spatial habitat features and integrate model output and field data. This ecosystem characterization was conducted as part of efforts to link field data, geographic information, and the dynamic simulation of multiple habitats. The goal of these efforts is to examine ecological structure, function, and change in fringing environments of lower Chesapeake Bay.},\n\tjournal = {Estuaries},\n\tauthor = {Buzzelli, Christopher P.},\n\tyear = {1998},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The fringing environments of lower Chesapeake Bay include sandy shoals, seagrass meadows, intertidal mud flats, and marshes. A characterization of a fringing ecosystem was conducted to provide initialization and calibration data for the development of a simulation model. The model simulates primary production and material exchange in the littoral zone of lower Chesapeake Bay. Carbon (C) and nitrogen (N) properties of water and sediments from sand, seagrass, intertidal silt-mud, and intertidal marsh habitats of the Goodwin Island (located within the Chesapeake Bay National Estuarine Research Reserve in Virginia, CBNERR-VA) were determined seasonally. Spatial and temporal differences in sediment microalgal biomass among the habitats were assessed along with annual variations in the distribution and abundance of Zostera marina L. and Spartina alterniflora Loisel. Phytoplankton biomass displayed some seasonality related to riverine discharge, but sediment microalgal biomass did not vary spatially or seasonally. Macrophytes in both subtidal and intertidal habitats exhibited seasonal biomass patterns that were consistent with other Atlantic estuarine ecosystems. Marsh sediment organic carbon and inorganic nitrogen differed significantly from that of the sand, seagrass, and silt habitats. The only biogeochemical variable that exhibited seasonality was low marsh NH4+. The subtidal sediments were consistent temporally in their carbon and nitrogen content despite seasonal changes in seagrass abundance. Eelgrass has a comparatively low C:N ratio and is a potential N sink for the ecosystem. Changes in the composition or size of the vegetated habitats could have a dramatic influence over resource partitioning within the ecosystem. A spatial database (or geographic information system, GIS) of the Goodwin Islands site has been initiated to track long-term spatial habitat features and integrate model output and field data. This ecosystem characterization was conducted as part of efforts to link field data, geographic information, and the dynamic simulation of multiple habitats. The goal of these efforts is to examine ecological structure, function, and change in fringing environments of lower Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Dynamic simulation of littoral zone habitats in lower Chesapeake Bay. II. Seagrass habitat primary production and water quality relationships.\n \n \n \n\n\n \n Buzzelli, C. P.; Wetzel, R. L.; and Meyers, M. B.\n\n\n \n\n\n\n Estuaries. 1998.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{buzzelli_dynamic_1998,\n\ttitle = {Dynamic simulation of littoral zone habitats in lower {Chesapeake} {Bay}. {II}. {Seagrass} habitat primary production and water quality relationships},\n\tdoi = {10.2307/1353272},\n\tabstract = {Seagrasses are indicators of ecosystem state because they are sensitive to variations in water composition and clarity resulting from watershed-level impacts. A simulation model designed to study Zostera marina (eelgrass) habitat dynamics in a variable littoral zone environment was used to address the potential ecological responses to eutrophication in lower Chesapeake Bay. The adjacent channel boundary environment is a source of dissolved and particulate materials to the littoral zone. In the simulations, concentrations of key water quality variables in the adjacent estuarine channel boundary were either halved or doubled relative to the base case to investigate light versus nitrogen effects. The role of the seagrass meadow in littoral zone carbon and nitrogen dynamics was evaluated when meadow size was changed in the model. Particulate and dissolved organic carbon accounted for 83\\% of the submarine light attenuation in the seagrass meadow. In all model runs, the water column concentrations of chlorophyll a and dissolved inorganic nitrogen (DIN) were below the habitat criteria proposed as critical to seagrass survival. Eelgrass community production was carefully regulated by the interactive effects of light, nitrogen, and grazing on epiphyte growth. Increased eelgrass coverage in the littoral zone led to a simulated doubling of ecosystem primary production but reduced the fraction of production by planktonic and sediment microalgae. The simulation model presented here demonstrated the importance of material input from the channel in littoral zone biogeochemical dynamics. Submarine light regulated primary production more strongly than inorganic nitrogen concentrations in the model. External DIN concentrations influenced seagrass survival indirectly: enrichment stimulated growth of epiphytes and phytoplankton and promoted shading of the seagrass leaf. The model was based upon a unimpacted ecosystem and deteriorated water quality negatively influenced primary production greater than the increases triggered by improved conditions. Increased material loading to the littoral zone reduced submarine light availability, increased phytoplankton production, lowered ecosystem production, and reduced subtidal vegetated habitat. This simulation model of the estuarine littoral zone model combines hydrodynamics, biogeochemical sources and sinks, and living resources in order to better understand structure, function, and change in aquatic ecosystems.},\n\tjournal = {Estuaries},\n\tauthor = {Buzzelli, Christopher P. and Wetzel, Richard L. and Meyers, Mark B.},\n\tyear = {1998},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Seagrasses are indicators of ecosystem state because they are sensitive to variations in water composition and clarity resulting from watershed-level impacts. A simulation model designed to study Zostera marina (eelgrass) habitat dynamics in a variable littoral zone environment was used to address the potential ecological responses to eutrophication in lower Chesapeake Bay. The adjacent channel boundary environment is a source of dissolved and particulate materials to the littoral zone. In the simulations, concentrations of key water quality variables in the adjacent estuarine channel boundary were either halved or doubled relative to the base case to investigate light versus nitrogen effects. The role of the seagrass meadow in littoral zone carbon and nitrogen dynamics was evaluated when meadow size was changed in the model. Particulate and dissolved organic carbon accounted for 83% of the submarine light attenuation in the seagrass meadow. In all model runs, the water column concentrations of chlorophyll a and dissolved inorganic nitrogen (DIN) were below the habitat criteria proposed as critical to seagrass survival. Eelgrass community production was carefully regulated by the interactive effects of light, nitrogen, and grazing on epiphyte growth. Increased eelgrass coverage in the littoral zone led to a simulated doubling of ecosystem primary production but reduced the fraction of production by planktonic and sediment microalgae. The simulation model presented here demonstrated the importance of material input from the channel in littoral zone biogeochemical dynamics. Submarine light regulated primary production more strongly than inorganic nitrogen concentrations in the model. External DIN concentrations influenced seagrass survival indirectly: enrichment stimulated growth of epiphytes and phytoplankton and promoted shading of the seagrass leaf. The model was based upon a unimpacted ecosystem and deteriorated water quality negatively influenced primary production greater than the increases triggered by improved conditions. Increased material loading to the littoral zone reduced submarine light availability, increased phytoplankton production, lowered ecosystem production, and reduced subtidal vegetated habitat. This simulation model of the estuarine littoral zone model combines hydrodynamics, biogeochemical sources and sinks, and living resources in order to better understand structure, function, and change in aquatic ecosystems.\n
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\n \n\n \n \n \n \n \n Effects of different submersed macrophytes on sediment biogeochemistry.\n \n \n \n\n\n \n Wigand, C.; Stevenson, J. C.; and Cornwell, J. C.\n\n\n \n\n\n\n Aquatic Botany. 1997.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{wigand_effects_1997,\n\ttitle = {Effects of different submersed macrophytes on sediment biogeochemistry},\n\tdoi = {10.1016/S0304-3770(96)01108-4},\n\tabstract = {Porewater phosphate levels in submersed macrophyte grassbeds varied among years in the upper Chesapeake Bay (Maryland, USA) coincident with macrophyte species variation during these same years (1990, 1993, 1995). When native, deep-rooted Vallisneria americana Michx. was a codominant in the grassbed, the porewater phosphate concentrations were significantly lower (P {\\textbackslash}textless 0.001) than concentrations when the exotic, shallow-rooted species Hydrilla verticillata (L.f.) Royle and Myriophyllum spicatum L. were codominants. There were significant relationships (P {\\textbackslash}textless 0.001) between solid-phase inorganic phosphorus and reactive metals (Fe, Mn) in both native and exotic grassbeds. However, the slopes of the regression relationships between years were significantly different (P {\\textbackslash}textless 0.001), suggesting greater retention of inorganic phosphorus in sediments when V. americana was a codominant at the site. In addition, significant relationships between reactive manganese and iron in the sediments were observed, but the coefficient of determination was statistically greater (P {\\textbackslash}textless 0.001) when V. americana was a codominant at the site. Furthermore, plant cores of V. americana and H. verticillata had noticeably different sediment redox profiles, with the oxidation-reduction status of V. americana sediments being more oxidized in the root zone (i.e., + 125 mV vs - 5 mV at 4 cm depth). These data suggest that macrophyte species composition can alter sediment biogeochemistry resulting in varying porewater phosphate and solid-phase phosphorus and metal levels. Possible explanations for these biogeochemical differences may be attributed to morphological differences among macrophyte species (i.e., root/shoot ratio, canopy type, growth form) and differences in root oxygenation capabilities.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Wigand, Cathleen and Stevenson, J. Court and Cornwell, Jeffry C.},\n\tyear = {1997},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Porewater phosphate levels in submersed macrophyte grassbeds varied among years in the upper Chesapeake Bay (Maryland, USA) coincident with macrophyte species variation during these same years (1990, 1993, 1995). When native, deep-rooted Vallisneria americana Michx. was a codominant in the grassbed, the porewater phosphate concentrations were significantly lower (P \\textless 0.001) than concentrations when the exotic, shallow-rooted species Hydrilla verticillata (L.f.) Royle and Myriophyllum spicatum L. were codominants. There were significant relationships (P \\textless 0.001) between solid-phase inorganic phosphorus and reactive metals (Fe, Mn) in both native and exotic grassbeds. However, the slopes of the regression relationships between years were significantly different (P \\textless 0.001), suggesting greater retention of inorganic phosphorus in sediments when V. americana was a codominant at the site. In addition, significant relationships between reactive manganese and iron in the sediments were observed, but the coefficient of determination was statistically greater (P \\textless 0.001) when V. americana was a codominant at the site. Furthermore, plant cores of V. americana and H. verticillata had noticeably different sediment redox profiles, with the oxidation-reduction status of V. americana sediments being more oxidized in the root zone (i.e., + 125 mV vs - 5 mV at 4 cm depth). These data suggest that macrophyte species composition can alter sediment biogeochemistry resulting in varying porewater phosphate and solid-phase phosphorus and metal levels. Possible explanations for these biogeochemical differences may be attributed to morphological differences among macrophyte species (i.e., root/shoot ratio, canopy type, growth form) and differences in root oxygenation capabilities.\n
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\n \n\n \n \n \n \n \n Seasonal pulses of turbidity and their relations to eelgrass (Zostera marina L.) survival in an estuary.\n \n \n \n\n\n \n Moore, K. A.; Wetzel, R. L.; and Orth, R. J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1997.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{moore_seasonal_1997,\n\ttitle = {Seasonal pulses of turbidity and their relations to eelgrass ({Zostera} marina {L}.) survival in an estuary},\n\tdoi = {10.1016/S0022-0981(96)02774-8},\n\tabstract = {The light environment of one Chesapeake Bay tributary where seagrasses have decreased in abundance was described using both continuous and discrete measures of irradiance and related to the growth and survival of transplanted eelgrass (Zostera marina L.). After 8 months of continuous growth at an upriver site, a decline and eventual complete loss of eelgrass transplants began during a month long (May-June) period of increased turbidity (K(d) {\\textbackslash}textgreater 3.0). Transplant loss continued even after light conditions improved (K(d) {\\textbackslash}textless 2.0). At a downriver site where there has been some natural seagrass regrowth, the pulse of high turbidity was not as evident and transplants survived. Other than this spring period of high turbidity at the upriver site, the light environments of the two areas were similar with minimum turbidity in January and maximum in the spring and summer. Annual median daily attenuation coefficients (K(d)) at the upriver and downriver sites were 1.77 and 1.96, respectively, and were not significantly different (P = 0.49). Total downwelling quantum flux at transplant depths of 0.8 m below mean sea level were 2618 and 2556 mol · m-2 · yr-1 or approximately 24.9 and 24.3\\% of annual solar PAR. The high spring turbidity pulse corresponded to an increase in non-chlorophyll particulate matter. Chlorophyll specific attenuation (K(c)) accounted for 6.7-9.0\\% of K(d) in June. Differences in attenuation were greatest in the 400-500 nm spectral region. Therefore, measures of total PAR attenuation can overestimate the usable irradiance available to the macrophytes. Scalar quantum fluxes during the period of elevated turbidity were 2.7 and 13.4 mols · m-2 · day m at the upriver and downriver sites. The duration and intensity of total PAR measured upriver during this period were insufficient to support eelgrass growth and survival, and below literature estimates for eelgrass community light compensation at in situ temperatures (20-25°C). Therefore late spring, month-long pulses in turbidity, such as measured here can account for the loss of transplanted vegetation and, potentially, explain lack of successful recruitment into formerly vegetated upriver sites.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Moore, Kenneth A. and Wetzel, Richard L. and Orth, Robert J.},\n\tyear = {1997},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The light environment of one Chesapeake Bay tributary where seagrasses have decreased in abundance was described using both continuous and discrete measures of irradiance and related to the growth and survival of transplanted eelgrass (Zostera marina L.). After 8 months of continuous growth at an upriver site, a decline and eventual complete loss of eelgrass transplants began during a month long (May-June) period of increased turbidity (K(d) \\textgreater 3.0). Transplant loss continued even after light conditions improved (K(d) \\textless 2.0). At a downriver site where there has been some natural seagrass regrowth, the pulse of high turbidity was not as evident and transplants survived. Other than this spring period of high turbidity at the upriver site, the light environments of the two areas were similar with minimum turbidity in January and maximum in the spring and summer. Annual median daily attenuation coefficients (K(d)) at the upriver and downriver sites were 1.77 and 1.96, respectively, and were not significantly different (P = 0.49). Total downwelling quantum flux at transplant depths of 0.8 m below mean sea level were 2618 and 2556 mol · m-2 · yr-1 or approximately 24.9 and 24.3% of annual solar PAR. The high spring turbidity pulse corresponded to an increase in non-chlorophyll particulate matter. Chlorophyll specific attenuation (K(c)) accounted for 6.7-9.0% of K(d) in June. Differences in attenuation were greatest in the 400-500 nm spectral region. Therefore, measures of total PAR attenuation can overestimate the usable irradiance available to the macrophytes. Scalar quantum fluxes during the period of elevated turbidity were 2.7 and 13.4 mols · m-2 · day m at the upriver and downriver sites. The duration and intensity of total PAR measured upriver during this period were insufficient to support eelgrass growth and survival, and below literature estimates for eelgrass community light compensation at in situ temperatures (20-25°C). Therefore late spring, month-long pulses in turbidity, such as measured here can account for the loss of transplanted vegetation and, potentially, explain lack of successful recruitment into formerly vegetated upriver sites.\n
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\n \n\n \n \n \n \n \n Observations of tidal flux between a submersed aquatic plant stand and the adjacent channel in the Potomac River near Washington, D.C.\n \n \n \n\n\n \n Rybicki, N. B.; Jenter, H. L.; Carter, V.; Baltzer, R. A.; and Turtora, M.\n\n\n \n\n\n\n Limnology and Oceanography. 1997.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{rybicki_observations_1997,\n\ttitle = {Observations of tidal flux between a submersed aquatic plant stand and the adjacent channel in the {Potomac} {River} near {Washington}, {D}.{C}.},\n\tdoi = {10.4319/lo.1997.42.2.0307},\n\tabstract = {Dye injection studies and direct velocity and water-level measurements were made in macrophyte stands and adjacent channels in order to observe the effects of the macrophyte stand on flow and mass exchange in the tidal Potomac River. During the summer, dense stands of submersed aquatic plants cover most shoals {\\textbackslash}textless2 m deep. Continuous summertime water-level records within a submersed aquatic plant stand and in the adjacent channel revealed time-varying gradients in water-surface elevation between the two areas. Water-level gradients are created by differing rates of tidal water-level change in vegetated and unvegetated areas. Results were consistent with the idea that on a rising tide the water was slower to enter a macrophyte stand, and on a falling tide it was slower to leave it. Differences in water elevation between the stand and the open channel generated components of velocity in the stand that were at right angles to the line of flow in the channel. Seasonal differences in flow speed and direction over the shoals indicate substantial differences in resistance to flow as a result of the vegetation.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Rybicki, Nancy B. and Jenter, Harry L. and Carter, Virginia and Baltzer, Robert A. and Turtora, Michael},\n\tyear = {1997},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Dye injection studies and direct velocity and water-level measurements were made in macrophyte stands and adjacent channels in order to observe the effects of the macrophyte stand on flow and mass exchange in the tidal Potomac River. During the summer, dense stands of submersed aquatic plants cover most shoals \\textless2 m deep. Continuous summertime water-level records within a submersed aquatic plant stand and in the adjacent channel revealed time-varying gradients in water-surface elevation between the two areas. Water-level gradients are created by differing rates of tidal water-level change in vegetated and unvegetated areas. Results were consistent with the idea that on a rising tide the water was slower to enter a macrophyte stand, and on a falling tide it was slower to leave it. Differences in water elevation between the stand and the open channel generated components of velocity in the stand that were at right angles to the line of flow in the channel. Seasonal differences in flow speed and direction over the shoals indicate substantial differences in resistance to flow as a result of the vegetation.\n
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\n \n\n \n \n \n \n \n Facilitation of phosphate assimilation by aquatic mycorrhizae of Vallisneria americana Michx.\n \n \n \n\n\n \n Wigand, C.; and Stevenson, J. C.\n\n\n \n\n\n\n Hydrobiologia. 1997.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{wigand_facilitation_1997,\n\ttitle = {Facilitation of phosphate assimilation by aquatic mycorrhizae of {Vallisneria} americana {Michx}},\n\tdoi = {10.1007/978-94-011-5648-6_4},\n\tabstract = {Presence of vesicular-arbuscular mycorrhizal fungi was found to enhance phosphate uptake in the submersed plant Vallisneria americana compared with plants treated with a fungicidal medium (i.e., Captan). Incorporation of 33P-orthophosphate into root tissue in short-term incubations was over 85\\% greater for plants with active mycorrhizae. In addition, we measured a fine-scale iron gradient and elevated concentrations of solid-phase phosphate in the extensive sheath surrounding the roots. The coupling of fungal symbionts with phosphorus storage in the sheath may be an important mechanism of phosphate assimilation in submersed aquatic macrophytes. Contrary to the effect on phosphate uptake, we did not find that 15NH4 assimilation by Vallisneria americana roots was enhanced by the presence of the mycorrhizal association.},\n\tjournal = {Hydrobiologia},\n\tauthor = {Wigand, Cathleen and Stevenson, J. Court},\n\tyear = {1997},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Presence of vesicular-arbuscular mycorrhizal fungi was found to enhance phosphate uptake in the submersed plant Vallisneria americana compared with plants treated with a fungicidal medium (i.e., Captan). Incorporation of 33P-orthophosphate into root tissue in short-term incubations was over 85% greater for plants with active mycorrhizae. In addition, we measured a fine-scale iron gradient and elevated concentrations of solid-phase phosphate in the extensive sheath surrounding the roots. The coupling of fungal symbionts with phosphorus storage in the sheath may be an important mechanism of phosphate assimilation in submersed aquatic macrophytes. Contrary to the effect on phosphate uptake, we did not find that 15NH4 assimilation by Vallisneria americana roots was enhanced by the presence of the mycorrhizal association.\n
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\n \n\n \n \n \n \n \n Effect of increasing photon irradiance on the growth of Vallisneria americana in the tidal Potomac River.\n \n \n \n\n\n \n Carter, V.; Rybicki, N. B.; and Turtora, M.\n\n\n \n\n\n\n Aquatic Botany. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{carter_effect_1996,\n\ttitle = {Effect of increasing photon irradiance on the growth of {Vallisneria} americana in the tidal {Potomac} {River}},\n\tdoi = {10.1016/0304-3770(96)01051-0},\n\tabstract = {Following declines in submersed macrophyte populations in tidal ecosystems, revegetation of areas devoid of macrophytes may be sudden and rapid or may not occur for years. Declines of submersed macrophyte populations in the Chesapeake Bay and the tidal Potomac River have been attributed to insufficient light in the water column; however, the role of light in promoting revegetation has never been unequivocally documented. Photon irradiance was artificially increased for Vallisneria americana transplants in two unvegetated embayments in the otherwise vegetated freshwater tidal Potomac River: Pohick Bay and Belmont Bay. Pohick Bay had high nutrient concentrations and frequent algal blooms. Belmont Bay was broader and shallower than Pohick Bay with turbidity resulting from wind- driven resuspension of sediment. The total number of plants of V. americana in the lighted cages was 7.5 times higher than that in the unlighted cages at Pohick Bay and 11 times higher than that in the unlighted control cages in Belmont Bay. The biomass in the lighted cages was 11-fold higher in Belmont Bay and 38-fold higher in Pohick Bay than that in the control cages. Plants were less numerous and more robust in lighted cages in Pohick Bay than in Belmont Bay.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B. and Turtora, Michael},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Following declines in submersed macrophyte populations in tidal ecosystems, revegetation of areas devoid of macrophytes may be sudden and rapid or may not occur for years. Declines of submersed macrophyte populations in the Chesapeake Bay and the tidal Potomac River have been attributed to insufficient light in the water column; however, the role of light in promoting revegetation has never been unequivocally documented. Photon irradiance was artificially increased for Vallisneria americana transplants in two unvegetated embayments in the otherwise vegetated freshwater tidal Potomac River: Pohick Bay and Belmont Bay. Pohick Bay had high nutrient concentrations and frequent algal blooms. Belmont Bay was broader and shallower than Pohick Bay with turbidity resulting from wind- driven resuspension of sediment. The total number of plants of V. americana in the lighted cages was 7.5 times higher than that in the unlighted cages at Pohick Bay and 11 times higher than that in the unlighted control cages in Belmont Bay. The biomass in the lighted cages was 11-fold higher in Belmont Bay and 38-fold higher in Pohick Bay than that in the control cages. Plants were less numerous and more robust in lighted cages in Pohick Bay than in Belmont Bay.\n
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\n \n\n \n \n \n \n \n Ecosystem model of an estuarine submersed plant community: Calibration and simulation of eutrophication responses.\n \n \n \n\n\n \n Madden, C. J.; and Kemp, W. M.\n\n\n \n\n\n\n Estuaries. 1996.\n \n\n\n\n
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@article{madden_ecosystem_1996,\n\ttitle = {Ecosystem model of an estuarine submersed plant community: {Calibration} and simulation of eutrophication responses},\n\tdoi = {10.2307/1352463},\n\tabstract = {As water quality in the Chesapeake Bay has declined over recent decades, formerly healthy submersed plant communities have disappeared from littoral areas of the mesohaline estuary. A dynamic simulation model of shallow regions of bay tributaries ({\\textbackslash}textless1 m) was developed to investigate growth responses of submersed vascular plants to eutrophication and habitat degradation. Our objectives were to elucidate mechanisms responsible for the decline and to evaluate conditions required for plant restoration and survival. State variables in the model are plant leaves, roots, phytoplankton, epiphytes, and detrital material. The model calculates biomass pools and biogeochemical rate processes over annual cycles with a time step of 6 h. Simulations were performed to investigate the influence of phytoplankton and epiphytes on the underwater light environment, how die balance of limiting resources (light and nutrients) controls growth and productivity of submersed plants, and conditions necessary for the restoration of submersed vegetation. Model output for submersed plants was calibrated to baseline data from the mid 1970s (r2 = 0.86); simulations reproduced declines in plant biomass with increasing nutrient enrichment. Model experiments showed that by increasing nutrient inputs 40\\% above levels observed in the 1960s, submersed plants disappeared within 1-2 yr due to enhanced growth of phytoplankton and epiphytes, which reduced light below required levels. Epiphytes were more important than were phytoplankton in attenuating light. The relationship between nutrient enrichment and plant loss rate was complex, as epiphyte density on leaf surfaces was not linearly related to nutrient levels. Relatively small nutrient increases could have a large effect on submersed plants because epiphyte density on leaves increased exponentially as leaf surface area decreased. Exchanges of organic carbon and nutrients between leaf and root compartments were seasonally variable and were critical for survival of submersed plants. The amount of root-rhizome material available for regrowth could control the outcome of nutrient reduction strategies. Consequently, model predictions of plant restoration success were highly dependent on initial conditions. The model is being used successfully as a research tool to interpret ecological relationships in the ongoing re-evaluation of management alternatives for submersed plant restoration.},\n\tjournal = {Estuaries},\n\tauthor = {Madden, Christopher J. and Kemp, W. Michael},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n\n\n
\n As water quality in the Chesapeake Bay has declined over recent decades, formerly healthy submersed plant communities have disappeared from littoral areas of the mesohaline estuary. A dynamic simulation model of shallow regions of bay tributaries (\\textless1 m) was developed to investigate growth responses of submersed vascular plants to eutrophication and habitat degradation. Our objectives were to elucidate mechanisms responsible for the decline and to evaluate conditions required for plant restoration and survival. State variables in the model are plant leaves, roots, phytoplankton, epiphytes, and detrital material. The model calculates biomass pools and biogeochemical rate processes over annual cycles with a time step of 6 h. Simulations were performed to investigate the influence of phytoplankton and epiphytes on the underwater light environment, how die balance of limiting resources (light and nutrients) controls growth and productivity of submersed plants, and conditions necessary for the restoration of submersed vegetation. Model output for submersed plants was calibrated to baseline data from the mid 1970s (r2 = 0.86); simulations reproduced declines in plant biomass with increasing nutrient enrichment. Model experiments showed that by increasing nutrient inputs 40% above levels observed in the 1960s, submersed plants disappeared within 1-2 yr due to enhanced growth of phytoplankton and epiphytes, which reduced light below required levels. Epiphytes were more important than were phytoplankton in attenuating light. The relationship between nutrient enrichment and plant loss rate was complex, as epiphyte density on leaf surfaces was not linearly related to nutrient levels. Relatively small nutrient increases could have a large effect on submersed plants because epiphyte density on leaves increased exponentially as leaf surface area decreased. Exchanges of organic carbon and nutrients between leaf and root compartments were seasonally variable and were critical for survival of submersed plants. The amount of root-rhizome material available for regrowth could control the outcome of nutrient reduction strategies. Consequently, model predictions of plant restoration success were highly dependent on initial conditions. The model is being used successfully as a research tool to interpret ecological relationships in the ongoing re-evaluation of management alternatives for submersed plant restoration.\n
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\n \n\n \n \n \n \n \n \n A comparative analysis of eutrophication patterns in a temperate coastal lagoon.\n \n \n \n \n\n\n \n Boynton, W. R.; Murray, L.; Hagy, J. D.; Stokes, C.; and Kemp, W. M.\n\n\n \n\n\n\n Estuaries. 1996.\n \n\n\n\n
\n\n\n\n \n \n \"APaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{boynton_comparative_1996,\n\ttitle = {A comparative analysis of eutrophication patterns in a temperate coastal lagoon},\n\turl = {https://dx.doi.org/10.2307/1352459},\n\tdoi = {10.2307/1352459},\n\tabstract = {The coastal bays and lagoons of Maryland extend the full length of the state's Atlantic coast and compose a substantial ecosystem at the land-sea margin that is characterized by shallow depth, a well-mixed water column, slow exchange with the coastal ocean, and minimal freshwater input from the land. For at least 25 years, various types of measurements have been made intermittently in these systems, but almost no effort has been made to determine if water quality or habitat conditions have changed over the years or if distinctive spatial gradients in these features have developed in response to changing land uses. The purpose of this work was to examine this fragmented database and determine if such patterns have emerged and how they may be related to land uses. Turbidity, dissolved inorganic phosphate, algal biomass, and primary production rates in most areas of the coastal bays followed a regular seasonal pattern, which was well correlated with water temperature. Nitrate concentrations were low ({\\textbackslash}textless5 μM), and only modestly higher in tributary creeks ({\\textbackslash}textless20 μM). Additionally, there was little indication of the spring bloom typical of river-dominated systems. There does appear to be a strong spatial gradient in water quality conditions (more eutrophic in the upper bays, especially in tributary creeks). Comparisons of water quality data collected between 1970 and 1991 indicate little temporal change in most areas and some small improvements in a few areas, probably related to decreases in point-source discharges. Seagrass communities were once extensive in these systems but at present are restricted to the eastern portion of the lower bays where water clarity is sufficient to support plant survival. Even in these areas, seagrass densities have recently decreased. Examination of diel dissolved oxygen data collected in the summer indicates progressively larger diel excursions from lower to upper bays and from open bays to tributary subsystems; however, hypoxic conditions ({\\textbackslash}textless2 mg l-1) were rarely observed in any location. Nitrogen input data (point, surface runoff, groundwater, and atmospheric deposition to surface waters) were assembled for seven regions of the coastal bay system; annual loading rates ranged from 2.4 g N m-2 yr-1 to 39.7 g N m-2 yr-1. Compared with a sampling of loading rates to other coastal systems, those to the upper and lower bays were low while those to tributaries were moderate to high. Regression analysis indicated significant relationships between annual nitrogen loading rates and average annual total nitrogen and chlorophyll a concentrations in the water column. Similar analyses also indicated significant relationships between chlorophyll a and the magnitude of diel dissolved oxygen changes in the water column. It is concluded that these simple models, which could be improved with a well-designed monitoring program, could be used as quantitative management tools to relate habitat conditions to nutrient loading rates.},\n\tjournal = {Estuaries},\n\tauthor = {Boynton, W. R. and Murray, L. and Hagy, J. D. and Stokes, C. and Kemp, W. M.},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The coastal bays and lagoons of Maryland extend the full length of the state's Atlantic coast and compose a substantial ecosystem at the land-sea margin that is characterized by shallow depth, a well-mixed water column, slow exchange with the coastal ocean, and minimal freshwater input from the land. For at least 25 years, various types of measurements have been made intermittently in these systems, but almost no effort has been made to determine if water quality or habitat conditions have changed over the years or if distinctive spatial gradients in these features have developed in response to changing land uses. The purpose of this work was to examine this fragmented database and determine if such patterns have emerged and how they may be related to land uses. Turbidity, dissolved inorganic phosphate, algal biomass, and primary production rates in most areas of the coastal bays followed a regular seasonal pattern, which was well correlated with water temperature. Nitrate concentrations were low (\\textless5 μM), and only modestly higher in tributary creeks (\\textless20 μM). Additionally, there was little indication of the spring bloom typical of river-dominated systems. There does appear to be a strong spatial gradient in water quality conditions (more eutrophic in the upper bays, especially in tributary creeks). Comparisons of water quality data collected between 1970 and 1991 indicate little temporal change in most areas and some small improvements in a few areas, probably related to decreases in point-source discharges. Seagrass communities were once extensive in these systems but at present are restricted to the eastern portion of the lower bays where water clarity is sufficient to support plant survival. Even in these areas, seagrass densities have recently decreased. Examination of diel dissolved oxygen data collected in the summer indicates progressively larger diel excursions from lower to upper bays and from open bays to tributary subsystems; however, hypoxic conditions (\\textless2 mg l-1) were rarely observed in any location. Nitrogen input data (point, surface runoff, groundwater, and atmospheric deposition to surface waters) were assembled for seven regions of the coastal bay system; annual loading rates ranged from 2.4 g N m-2 yr-1 to 39.7 g N m-2 yr-1. Compared with a sampling of loading rates to other coastal systems, those to the upper and lower bays were low while those to tributaries were moderate to high. Regression analysis indicated significant relationships between annual nitrogen loading rates and average annual total nitrogen and chlorophyll a concentrations in the water column. Similar analyses also indicated significant relationships between chlorophyll a and the magnitude of diel dissolved oxygen changes in the water column. It is concluded that these simple models, which could be improved with a well-designed monitoring program, could be used as quantitative management tools to relate habitat conditions to nutrient loading rates.\n
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\n \n\n \n \n \n \n \n Zostera marina (eelgrass) growth and survival along a gradient ofnutrients and turbidity in the lower Chesapeake Bay.\n \n \n \n\n\n \n Moore, K. A.; Neckles, H. A.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{moore_zostera_1996,\n\ttitle = {Zostera marina (eelgrass) growth and survival along a gradient ofnutrients and turbidity in the lower {Chesapeake} {Bay}},\n\tdoi = {10.3354/meps142247},\n\tabstract = {Survival of transplanted Zostera marina L. (eelgrass), Z. marina growth,and environmental conditions were studied concurrently at a number of sitesin a southwestern tributary of the Chesapeake Bay to elucidate the factorslimiting macrophyte distribution in this region. Consistent differences insurvival of the transplants were observed, with no long-term survival at anyof the sites that were formerly vegetated with this species but thatcurrently remain unvegetated. Therefore, the current distribution of Z.marina likely represents the extent of suitable environmental conditions inthe region, and the lack of recovery into historically vegetated sites is notsolely due to lack of propagules. Poor long-term survival was related toseasonally high levels of water column light attenuation. Fall transplantsdied by the end of summer following exposure to levels of high springturbidity (K(d) {\\textbackslash}textgreater 3.0). Accumulation of an epiphyte matrix during the latespring (0.36 to 1.14 g g-1 dry wt) may also have contributed to thisstress. Differences in water column nutrient levels among sites during thefall and winter (10 to 15 μM dissolved inorganic nitrogen and 1 μMdissolved inorganic phosphates) had no observable effect on epiphyteaccumulation or macrophyte growth. Salinity effects were minor and there wereno symptoms of disease. Although summertime conditions resulted indepressions in growth, they did not alone limit long-term survival. It issuggested that water quality conditions enhancing adequate seagrass growthduring the spring may be key to long-term Z. marina survival and successfulrecolonization in this region.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Moore, Kenneth A. and Neckles, Hilary A. and Orth, Robert J.},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Survival of transplanted Zostera marina L. (eelgrass), Z. marina growth,and environmental conditions were studied concurrently at a number of sitesin a southwestern tributary of the Chesapeake Bay to elucidate the factorslimiting macrophyte distribution in this region. Consistent differences insurvival of the transplants were observed, with no long-term survival at anyof the sites that were formerly vegetated with this species but thatcurrently remain unvegetated. Therefore, the current distribution of Z.marina likely represents the extent of suitable environmental conditions inthe region, and the lack of recovery into historically vegetated sites is notsolely due to lack of propagules. Poor long-term survival was related toseasonally high levels of water column light attenuation. Fall transplantsdied by the end of summer following exposure to levels of high springturbidity (K(d) \\textgreater 3.0). Accumulation of an epiphyte matrix during the latespring (0.36 to 1.14 g g-1 dry wt) may also have contributed to thisstress. Differences in water column nutrient levels among sites during thefall and winter (10 to 15 μM dissolved inorganic nitrogen and 1 μMdissolved inorganic phosphates) had no observable effect on epiphyteaccumulation or macrophyte growth. Salinity effects were minor and there wereno symptoms of disease. Although summertime conditions resulted indepressions in growth, they did not alone limit long-term survival. It issuggested that water quality conditions enhancing adequate seagrass growthduring the spring may be key to long-term Z. marina survival and successfulrecolonization in this region.\n
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\n \n\n \n \n \n \n \n Subaqueous soils: A pedological approach to the study of shallow-water habitats.\n \n \n \n\n\n \n Demas, G. P.; Rabenhorst, M. C.; and Stevenson, J. C.\n\n\n \n\n\n\n In Estuaries, 1996. \n \n\n\n\n
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@inproceedings{demas_subaqueous_1996,\n\ttitle = {Subaqueous soils: {A} pedological approach to the study of shallow-water habitats},\n\tdoi = {10.2307/1352228},\n\tabstract = {Science-based management of shallow-water habitats is limited by information on the spatial distribution of properties of sediments. This limitation in part stems from the lack of an adequate model or system to classify and delineate subaqueous soil types (sediments). Present classification systems are inadequate because the existing paradigm does not actually consider them as 'soils' but merely as 'sediments.' Field observations suggest that these sediments could be better understood as 'soils,' and the present paradigm could be modified to incorporate a new one-a pedological paradigm. We propose the application of a pedological paradigm for subaqueous soils of subtidal habitats to develop ecological interpretations of subaqueous soil types and apply an inventory of subaqueous soil resources for management of estuarine shallow-water habitats.},\n\tbooktitle = {Estuaries},\n\tauthor = {Demas, G. P. and Rabenhorst, M. C. and Stevenson, J. C.},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Science-based management of shallow-water habitats is limited by information on the spatial distribution of properties of sediments. This limitation in part stems from the lack of an adequate model or system to classify and delineate subaqueous soil types (sediments). Present classification systems are inadequate because the existing paradigm does not actually consider them as 'soils' but merely as 'sediments.' Field observations suggest that these sediments could be better understood as 'soils,' and the present paradigm could be modified to incorporate a new one-a pedological paradigm. We propose the application of a pedological paradigm for subaqueous soils of subtidal habitats to develop ecological interpretations of subaqueous soil types and apply an inventory of subaqueous soil resources for management of estuarine shallow-water habitats.\n
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\n \n\n \n \n \n \n \n Non-structural carbohydrate reserves of eelgrass Zostera marina.\n \n \n \n\n\n \n Burke, M. K.; Dennison, W. C.; and Moore, K. A.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{burke_non-structural_1996,\n\ttitle = {Non-structural carbohydrate reserves of eelgrass {Zostera} marina},\n\tdoi = {10.3354/meps137195},\n\tabstract = {The high minimum light requirement of eelgrass Zostera marina L. suggests that this species has difficulty in maintaining a positive carbon balance except under high light conditions The carbon balance of Z. marina can be studied by following seasonal changes in non-structural carbohydrate (NSC) reserves, however, little is known about the seasonal variation in NSC reserves in seagrasses or the influence of shading on NSC reserve content and distribution. Seasonal changes in eelgrass NSC reserves were measured in a shallow coastal lagoon, Chincoteague Bay, Maryland/Virginia, USA, near the southern edge of this species' distributional range. Concentrations of sugar varied seasonally in leaves, rhizomes and roots, with maximum concentrations occurring in the rhizomes. In contrast, starch concentrations did not vary with the season, but were highest in the roots. Seasonal peaks in rhizome NSC reserves parallel the spring and fall bimodal growth patterns observed for Z. marina in the region. Total NSC reserves change from an estimated 52 to 73 g m-2 in June to 4 to 18 g m-2 in January, or a decrease of 75 to 92 \\%. Experimental shading for 3 wk in the spring reduced (p {\\textbackslash}textless 0.001) sugar but not starch concentrations in leaves (48\\%), rhizomes (40\\%) and roots (51\\%). In addition, shading reduced (p {\\textbackslash}textless 0.05) leaf biomass (34\\%), root and rhizome biomass (23\\%) and density (27\\%). Potential NSC reserve storage during shading was reduced by an estimated 66\\%. Spring appears to be an important time lot both growth and storage of NSC reserves in Z. manna, and the NSC reserves are generally depleted throughout the remainder of the year. Turbidity during this springtime 'window of opportunity' may jeopardize subsequent survival as a result of inadequate NSC reserves to maintain a positive carbon balance during the rest of the year.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Burke, Marianne K. and Dennison, William C. and Moore, Kenneth A.},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The high minimum light requirement of eelgrass Zostera marina L. suggests that this species has difficulty in maintaining a positive carbon balance except under high light conditions The carbon balance of Z. marina can be studied by following seasonal changes in non-structural carbohydrate (NSC) reserves, however, little is known about the seasonal variation in NSC reserves in seagrasses or the influence of shading on NSC reserve content and distribution. Seasonal changes in eelgrass NSC reserves were measured in a shallow coastal lagoon, Chincoteague Bay, Maryland/Virginia, USA, near the southern edge of this species' distributional range. Concentrations of sugar varied seasonally in leaves, rhizomes and roots, with maximum concentrations occurring in the rhizomes. In contrast, starch concentrations did not vary with the season, but were highest in the roots. Seasonal peaks in rhizome NSC reserves parallel the spring and fall bimodal growth patterns observed for Z. marina in the region. Total NSC reserves change from an estimated 52 to 73 g m-2 in June to 4 to 18 g m-2 in January, or a decrease of 75 to 92 %. Experimental shading for 3 wk in the spring reduced (p \\textless 0.001) sugar but not starch concentrations in leaves (48%), rhizomes (40%) and roots (51%). In addition, shading reduced (p \\textless 0.05) leaf biomass (34%), root and rhizome biomass (23%) and density (27%). Potential NSC reserve storage during shading was reduced by an estimated 66%. Spring appears to be an important time lot both growth and storage of NSC reserves in Z. manna, and the NSC reserves are generally depleted throughout the remainder of the year. Turbidity during this springtime 'window of opportunity' may jeopardize subsequent survival as a result of inadequate NSC reserves to maintain a positive carbon balance during the rest of the year.\n
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\n \n\n \n \n \n \n \n Nutrient inputs to the Choptank River estuary: Implications for watershed management.\n \n \n \n\n\n \n Staver, L. W.; Staver, K. W.; and Stevenson, J. C.\n\n\n \n\n\n\n Estuaries. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{staver_nutrient_1996,\n\ttitle = {Nutrient inputs to the {Choptank} {River} estuary: {Implications} for watershed management},\n\tdoi = {10.2307/1352455},\n\tabstract = {Degraded water quality due to water column availability of nitrogen and phosphorus to algal species has been identified as the primary cause of the decline of submersed aquatic vegetation in Chesapeake Bay and its subestuaries. Determining the relative impacts of various nutrient delivery pathways on estuarine water quality is critical for developing effective strategies for reducing anthropogenic nutrient inputs to estuarine waters. This study investigated temporal and spatial patterns of nutrient inputs along an 80-km transect in the Choptank River, a coastal plain tributary and subestuary of Chesapeake Bay, from 1986 through 1991. The study period encompassed a wide range in freshwater discharge conditions that resulted in major changes in estuarine water quality. Watershed nitrogen loads to the Choptank River estuary are dominated by diffuse-source inputs, and are highly correlated to freshwater discharge volume. In years of below-average freshwater discharge, reduced nitrogen availability results in improved water quality throughout most of the Choptank River. Diffuse-source inputs are highly enriched in nitrogen relative to phosphorus, but point-source inputs of phosphorus from sewage treatment plants in the upper estuary reduce this imbalance, particularly during summer periods of low freshwater discharge. Diffuse-source nitrogen inputs result primarily from the discharge of groundwater contaminated by nitrate. Contamination is attributable to agricultural practices in the drainage basin where agricultural land use predominates. Groundwater discharge provides base flow to perennial streams in the upper regions of the watershed and seeps directly into tidal waters. Diffuse-source phosphorus inputs are highly episodic, occurring primarily via overland flow during storm events. Major reductions in diffuse-source nitrogen inputs under current land-use conditions will require modification of agricultural practices in the drainage basin to reduce entry rates of nitrate into shallow groundwater. Rates of subsurface nitrate delivery to tidal waters are generally lower from poorly-drained versus well-drained regions of the watershed, suggesting greater potential reductions of diffuse- source nitrogen loads per unit effort in the well-drained region of the watershed. Reductions in diffuse-source phosphorus loads will require long- term management of phosphorus levels in upper soil horizons.},\n\tjournal = {Estuaries},\n\tauthor = {Staver, Lorie W. and Staver, K. W. and Stevenson, J. Court},\n\tyear = {1996},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Degraded water quality due to water column availability of nitrogen and phosphorus to algal species has been identified as the primary cause of the decline of submersed aquatic vegetation in Chesapeake Bay and its subestuaries. Determining the relative impacts of various nutrient delivery pathways on estuarine water quality is critical for developing effective strategies for reducing anthropogenic nutrient inputs to estuarine waters. This study investigated temporal and spatial patterns of nutrient inputs along an 80-km transect in the Choptank River, a coastal plain tributary and subestuary of Chesapeake Bay, from 1986 through 1991. The study period encompassed a wide range in freshwater discharge conditions that resulted in major changes in estuarine water quality. Watershed nitrogen loads to the Choptank River estuary are dominated by diffuse-source inputs, and are highly correlated to freshwater discharge volume. In years of below-average freshwater discharge, reduced nitrogen availability results in improved water quality throughout most of the Choptank River. Diffuse-source inputs are highly enriched in nitrogen relative to phosphorus, but point-source inputs of phosphorus from sewage treatment plants in the upper estuary reduce this imbalance, particularly during summer periods of low freshwater discharge. Diffuse-source nitrogen inputs result primarily from the discharge of groundwater contaminated by nitrate. Contamination is attributable to agricultural practices in the drainage basin where agricultural land use predominates. Groundwater discharge provides base flow to perennial streams in the upper regions of the watershed and seeps directly into tidal waters. Diffuse-source phosphorus inputs are highly episodic, occurring primarily via overland flow during storm events. Major reductions in diffuse-source nitrogen inputs under current land-use conditions will require modification of agricultural practices in the drainage basin to reduce entry rates of nitrate into shallow groundwater. Rates of subsurface nitrate delivery to tidal waters are generally lower from poorly-drained versus well-drained regions of the watershed, suggesting greater potential reductions of diffuse- source nitrogen loads per unit effort in the well-drained region of the watershed. Reductions in diffuse-source phosphorus loads will require long- term management of phosphorus levels in upper soil horizons.\n
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\n \n\n \n \n \n \n \n Photosynthetic responses of eelgrass (Zostera marina L.) to light and sediment sulfide in a shallow barrier island lagoon.\n \n \n \n\n\n \n Goodman, J. L.; Moore, K. A.; and Dennison, W. C.\n\n\n \n\n\n\n Aquatic Botany. 1995.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{goodman_photosynthetic_1995,\n\ttitle = {Photosynthetic responses of eelgrass ({Zostera} marina {L}.) to light and sediment sulfide in a shallow barrier island lagoon},\n\tdoi = {10.1016/0304-3770(94)00444-Q},\n\tabstract = {Highly reducing sediments are prevalent in seagrass environments. Under anoxic conditions, hydrogen sulfide can accumulate as an end product of anaerobic respiration at levels which may be toxic to halophytes. The photosynthetic response of Zostera marina L. (eelgrass) to manipulations in sediment sulfide concentration and light regimes was examined in Chincoteague Bay in June 1991. Neutral density screens were used in a mesocosm experiment to decrease downwelling irradiance to 50 and 15\\% of insolation. Sediment sulfide levels were enriched using Na2S and lowered using FeSO4. Photosynthesis vs. irradiance (PI) relationships were determined experimentally at ten light levels throughout the 21 day experiment. Photoadaptation was detected in response to the previous 4 day light history of the plants, as maximum photosynthesis (Pmax) decreased in response to lower daily light levels. Negative impacts of sulfide on eelgrass in this study were observed through reductions in Pmax, increases in the light intensity at which gross photosynthesis equals respiration, and decreases in the initial slope of the PI curve. The effects of eutrophication through reduced light and increased sediment sulfide on Pmax were additive. Elevated sediment sulfide levels may contribute to seagrass loss in stressed areas as the potential for utilization of available light is reduced. © 1995.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Goodman, Jill L. and Moore, Kenneth A. and Dennison, William C.},\n\tyear = {1995},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Highly reducing sediments are prevalent in seagrass environments. Under anoxic conditions, hydrogen sulfide can accumulate as an end product of anaerobic respiration at levels which may be toxic to halophytes. The photosynthetic response of Zostera marina L. (eelgrass) to manipulations in sediment sulfide concentration and light regimes was examined in Chincoteague Bay in June 1991. Neutral density screens were used in a mesocosm experiment to decrease downwelling irradiance to 50 and 15% of insolation. Sediment sulfide levels were enriched using Na2S and lowered using FeSO4. Photosynthesis vs. irradiance (PI) relationships were determined experimentally at ten light levels throughout the 21 day experiment. Photoadaptation was detected in response to the previous 4 day light history of the plants, as maximum photosynthesis (Pmax) decreased in response to lower daily light levels. Negative impacts of sulfide on eelgrass in this study were observed through reductions in Pmax, increases in the light intensity at which gross photosynthesis equals respiration, and decreases in the initial slope of the PI curve. The effects of eutrophication through reduced light and increased sediment sulfide on Pmax were additive. Elevated sediment sulfide levels may contribute to seagrass loss in stressed areas as the potential for utilization of available light is reduced. © 1995.\n
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\n \n\n \n \n \n \n \n Dynamics of epiphytic photoautotrophs and heterotrophs in Zostera marina (eelgrass) microcosms: Responses to nutrient enrichment and grazing.\n \n \n \n\n\n \n Neckles, H. A.; Koepfler, E. T.; Haas, L. W.; Wetzel, R. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{neckles_dynamics_1994,\n\ttitle = {Dynamics of epiphytic photoautotrophs and heterotrophs in {Zostera} marina (eelgrass) microcosms: {Responses} to nutrient enrichment and grazing},\n\tdoi = {10.2307/1352407},\n\tabstract = {The combined effects of nutrient enrichment and grazing by isopods and amphipods on abundances of seagrass epiphytes were tested in Zostera marina L. (eelgrass) microcosms. Using epifluorescence microscopy, densities of epiphytic diatoms, cyanobacteria, heterotrophic flagellates, and heterotrophic bacteria were enumerated after 1 mo and 2 mo of treatment. In general, numbers of diatoms decreased, in the presence of grazers and showed little response to nutrient enrichment, whereas numbers of cyanobacteria increased with nutrient enrichment and showed little response to grazing. Thus, macrofaunal grazing maintained a photoautotrophic community domainated by cyanobacteria, particularly under nutrient enriched conditions. Following 2 mo of treatment, dense macroalgal growth under nutrient-enriched conditins with grazers absent appeared to limit populations of both epiphytic autotrophs. Patterns of abundance of heterotrophic bacteria suggested that the original bacteria population was nutrient limited. Bacteria populations may have been limited by organic carbon supplies at the end of the experiment. Abundances of heterotrophic flagellates and bacteria were strongly correlated on both sampling dates. Results suggest that heterotrophic flagellates might serve as a link between heterotrophic bacterial production and higher trophic levels in seagrass epiphyte food webs. © 1994 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Neckles, Hilary A. and Koepfler, Eric T. and Haas, Leonard W. and Wetzel, Richard L. and Orth, Robert J.},\n\tyear = {1994},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The combined effects of nutrient enrichment and grazing by isopods and amphipods on abundances of seagrass epiphytes were tested in Zostera marina L. (eelgrass) microcosms. Using epifluorescence microscopy, densities of epiphytic diatoms, cyanobacteria, heterotrophic flagellates, and heterotrophic bacteria were enumerated after 1 mo and 2 mo of treatment. In general, numbers of diatoms decreased, in the presence of grazers and showed little response to nutrient enrichment, whereas numbers of cyanobacteria increased with nutrient enrichment and showed little response to grazing. Thus, macrofaunal grazing maintained a photoautotrophic community domainated by cyanobacteria, particularly under nutrient enriched conditions. Following 2 mo of treatment, dense macroalgal growth under nutrient-enriched conditins with grazers absent appeared to limit populations of both epiphytic autotrophs. Patterns of abundance of heterotrophic bacteria suggested that the original bacteria population was nutrient limited. Bacteria populations may have been limited by organic carbon supplies at the end of the experiment. Abundances of heterotrophic flagellates and bacteria were strongly correlated on both sampling dates. Results suggest that heterotrophic flagellates might serve as a link between heterotrophic bacterial production and higher trophic levels in seagrass epiphyte food webs. © 1994 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Role of weather and water quality in population dynamics of submersed macrophytes in the tidal Potomac River.\n \n \n \n\n\n \n Carter, V.; Rybicki, N. B.; Landwehr, J. M.; and Turtora, M.\n\n\n \n\n\n\n Estuaries. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carter_role_1994-1,\n\ttitle = {Role of weather and water quality in population dynamics of submersed macrophytes in the tidal {Potomac} {River}},\n\tdoi = {10.2307/1352674},\n\tabstract = {Weather and water-quality data from 1980 to 1989 were correlated with fluctuations in submersed macrophyte populations in the tidal Potomac River near Washington, D.C., to elucidate causal relationships and explain population dynamics. Both reaches were unvegetated in 1980 when mean growing-season Secchi depths were {\\textbackslash}textless0.60 m. Macrophyte resurgence in the upper tidal river in 1983 was associated with a growing-season Secchi depth of 0.86 m, total suspended solids (TSS) of 17.7 mg l−1, chlorophyll a concentrations of 15.2 μg l−1, significantly higher than average percent available sunshine, and significantly lower than average wind speed. From 1983 to 1989, mean seasonal Secchi depths {\\textbackslash}textless0.65 m were associated with decrease in plant coverage and mean seasonal Secchi depths {\\textbackslash}textgreater0.65 were associated with increases in plant coverage. Changes in mean seasonal Secchi depth were related to changes in mean seasonal TSS and chlorophyll a concentration; mean Secchi depths {\\textbackslash}textgreater0.65 generally occur when seasonal mean TSS is {\\textbackslash}textless19 mg l−1 and seasonal mean chlorophyll a concentration is ≤15 μg l−1. Secchi depth is highly correlated with plant growth in the upper tidal river and chlorophyll a and TSS with plant growth in the lower tidal river. Wind speed is an important influence on plant growth in both reaches. © 1994, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Estuaries},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B. and Landwehr, Jurate M. and Turtora, Michael},\n\tyear = {1994},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Weather and water-quality data from 1980 to 1989 were correlated with fluctuations in submersed macrophyte populations in the tidal Potomac River near Washington, D.C., to elucidate causal relationships and explain population dynamics. Both reaches were unvegetated in 1980 when mean growing-season Secchi depths were \\textless0.60 m. Macrophyte resurgence in the upper tidal river in 1983 was associated with a growing-season Secchi depth of 0.86 m, total suspended solids (TSS) of 17.7 mg l−1, chlorophyll a concentrations of 15.2 μg l−1, significantly higher than average percent available sunshine, and significantly lower than average wind speed. From 1983 to 1989, mean seasonal Secchi depths \\textless0.65 m were associated with decrease in plant coverage and mean seasonal Secchi depths \\textgreater0.65 were associated with increases in plant coverage. Changes in mean seasonal Secchi depth were related to changes in mean seasonal TSS and chlorophyll a concentration; mean Secchi depths \\textgreater0.65 generally occur when seasonal mean TSS is \\textless19 mg l−1 and seasonal mean chlorophyll a concentration is ≤15 μg l−1. Secchi depth is highly correlated with plant growth in the upper tidal river and chlorophyll a and TSS with plant growth in the lower tidal river. Wind speed is an important influence on plant growth in both reaches. © 1994, Estuarine Research Federation. All rights reserved.\n
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\n \n\n \n \n \n \n \n The presence and possible ecological significance of mycorrhizae of the submersed macrophyte, Vallisneria americana.\n \n \n \n\n\n \n Wigand, C.; and Stevenson, J. C.\n\n\n \n\n\n\n Estuaries. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{wigand_presence_1994,\n\ttitle = {The presence and possible ecological significance of mycorrhizae of the submersed macrophyte, {Vallisneria} americana},\n\tdoi = {10.2307/1352570},\n\tabstract = {Atypical fungal vesicles and arbuscules were found within the roots of the submersed macrophyte Vallisneria americana collected at the tidal fresh headwaters of the Chesapeake Bay (Susquehanna flats) in July 1991 and 1992, suggesting the presence of a myocrrhizal association. In order to determine whether the presence of the fungus facilitates phosphorus uptake and plant growth, V. americana cores were placed in separate pots in an aquatic greenhouse and were given one of the following treatments: control, fungicide (Captan) application, or fungicide plus phosphate enrichment. Fungicide addition resulted in significantly decreased shoot elongation rates and chlorophyll a production; phosphate enrichment plus fungicide restored plant growth to control levels. Low nitrogen in plant tissues of fungicide treatment groups suggests nitrogen uptake may also be promoted by the fungal association. A second laboratory experiment with V. americana grown from turions demonstrated the negative effects of the fungicide are only evident on plant growth when fungal infection is present, indicating the fungicide was not directly toxic to the macrophyte, but acted by disrupting a mycorrhizal relationship. This study supports the hypothesis that mycorrhizae are important in nutrient acquisition and growth of Vallisneria in an estuarine environment. © 1994 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Wigand, Cathleen and Stevenson, J. Court},\n\tyear = {1994},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Atypical fungal vesicles and arbuscules were found within the roots of the submersed macrophyte Vallisneria americana collected at the tidal fresh headwaters of the Chesapeake Bay (Susquehanna flats) in July 1991 and 1992, suggesting the presence of a myocrrhizal association. In order to determine whether the presence of the fungus facilitates phosphorus uptake and plant growth, V. americana cores were placed in separate pots in an aquatic greenhouse and were given one of the following treatments: control, fungicide (Captan) application, or fungicide plus phosphate enrichment. Fungicide addition resulted in significantly decreased shoot elongation rates and chlorophyll a production; phosphate enrichment plus fungicide restored plant growth to control levels. Low nitrogen in plant tissues of fungicide treatment groups suggests nitrogen uptake may also be promoted by the fungal association. A second laboratory experiment with V. americana grown from turions demonstrated the negative effects of the fungicide are only evident on plant growth when fungal infection is present, indicating the fungicide was not directly toxic to the macrophyte, but acted by disrupting a mycorrhizal relationship. This study supports the hypothesis that mycorrhizae are important in nutrient acquisition and growth of Vallisneria in an estuarine environment. © 1994 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Zostera marina L. growth response to atrazine in root-rhizome and whole plant exposure experiments.\n \n \n \n\n\n \n Schwarzschild, A. C.; MacIntyre, W. G.; Moore, K. A.; and Laurence Libelo, E.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{schwarzschild_zostera_1994,\n\ttitle = {Zostera marina {L}. growth response to atrazine in root-rhizome and whole plant exposure experiments},\n\tdoi = {10.1016/0022-0981(94)90158-9},\n\tabstract = {Atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino-]-s-triazine), a triazine herbicide, is one of the most widely used herbicides in the Chesapeake Bay watershed. Increased use of atrazine in the 1970s coincided with a decline in the abundance of Zostera marina L. (eelgrass). Ground-water surveys have found atrazine in concentrations that may affect eelgrass growth and survival. The effects of atrazine in groundwater discharges on the growth of eelgrass through root-rhizome exposure were examined in laboratory systems. A long term, dynamic, groundwater simulation study was conducted with atrazine concentrations ranging from 0.0 to 2.5 mg·l-1. No significant effects on chlorophyll content, growth or survival were detected. A static root-rhizome exposure experiment was conducted using split chamber exposure systems to verify these results, atrazine concentrations were increased by an order of magnitude. Neither mortality nor significant effects on plant growth were detected (maximum atrazine concentration 7.6 mg·l-1). A static, whole plant exposure experiment was conducted, and mortality was observed at atrazine concentrations of 1.9 mg·l-1 and above. This work suggests that eelgrass is not susceptible to atrazine through root-rhizome uptake, and that atrazine exposure via groundwater seepage did not cause the declines in eelgrass abundance and distribution. © 1994.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Schwarzschild, Arthur C. and MacIntyre, William G. and Moore, Kenneth A. and Laurence Libelo, E.},\n\tyear = {1994},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
\n
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\n Atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino-]-s-triazine), a triazine herbicide, is one of the most widely used herbicides in the Chesapeake Bay watershed. Increased use of atrazine in the 1970s coincided with a decline in the abundance of Zostera marina L. (eelgrass). Ground-water surveys have found atrazine in concentrations that may affect eelgrass growth and survival. The effects of atrazine in groundwater discharges on the growth of eelgrass through root-rhizome exposure were examined in laboratory systems. A long term, dynamic, groundwater simulation study was conducted with atrazine concentrations ranging from 0.0 to 2.5 mg·l-1. No significant effects on chlorophyll content, growth or survival were detected. A static root-rhizome exposure experiment was conducted using split chamber exposure systems to verify these results, atrazine concentrations were increased by an order of magnitude. Neither mortality nor significant effects on plant growth were detected (maximum atrazine concentration 7.6 mg·l-1). A static, whole plant exposure experiment was conducted, and mortality was observed at atrazine concentrations of 1.9 mg·l-1 and above. This work suggests that eelgrass is not susceptible to atrazine through root-rhizome uptake, and that atrazine exposure via groundwater seepage did not cause the declines in eelgrass abundance and distribution. © 1994.\n
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\n \n\n \n \n \n \n \n Assessing Water Quality with Submersed Aquatic Vegetation.\n \n \n \n\n\n \n Dennison, W. C.; Orth, R. J.; Moore, K. A.; Stevenson, J. C.; Carter, V.; Kollar, S.; Bergstrom, P. W.; and Batiuk, R. A.\n\n\n \n\n\n\n BioScience. 1993.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{dennison_assessing_1993,\n\ttitle = {Assessing {Water} {Quality} with {Submersed} {Aquatic} {Vegetation}},\n\tdoi = {10.2307/1311969},\n\tabstract = {Uses habitat requirements of submersed aquatic vegetation to characterize the water quality of Chesapeake Bay. Synthesis of information leading to the establishment of quantitative levels of relevant water quality parameters; Why the development of a habitat requirement approach for Chesapeake Bay could prove useful; Minimal light requirements of submersed aquatic vegetation; Conclusions.},\n\tjournal = {BioScience},\n\tauthor = {Dennison, William C. and Orth, Robert J. and Moore, Kenneth A. and Stevenson, J. Court and Carter, Virginia and Kollar, Stan and Bergstrom, Peter W. and Batiuk, Richard A.},\n\tyear = {1993},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Uses habitat requirements of submersed aquatic vegetation to characterize the water quality of Chesapeake Bay. Synthesis of information leading to the establishment of quantitative levels of relevant water quality parameters; Why the development of a habitat requirement approach for Chesapeake Bay could prove useful; Minimal light requirements of submersed aquatic vegetation; Conclusions.\n
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\n \n\n \n \n \n \n \n Environmental regulation of seed germination in Zostera marina L. (eelgrass) in Chesapeake Bay: effects of light, oxygen and sediment burial.\n \n \n \n\n\n \n Moore, K. A.; Orth, R. J.; and Nowak, J. F.\n\n\n \n\n\n\n Aquatic Botany. 1993.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{moore_environmental_1993,\n\ttitle = {Environmental regulation of seed germination in {Zostera} marina {L}. (eelgrass) in {Chesapeake} {Bay}: effects of light, oxygen and sediment burial},\n\tdoi = {10.1016/0304-3770(93)90054-Z},\n\tabstract = {The effects of light, oxygen and sediment burial on seed germination of Zostera marina L. were tested in two experiments beginning in 1987 and 1988. In 1987, seeds were placed in flow-through clear plastic tubes or buried at depths of 5, 15 and 25 mm in pots filled with seagrass sediments and held in an outdoor running seawater tank at ambient temperature, salinity and solar irradiance. The seeds began germinating in the sediments when water temperatures dropped to 15°C in mid-October and nearly all were germinated by December. Seeds held in the plastic tubes did not begin to germinate until mid-January. Again in 1988, seeds planted in pots germinated in October when temperatures decreased to 15°C; germination in the oxygenated water column was again delayed throughout the autumn and winter. However, seeds held in the water column in clear vials of deoxygenated water, without sediment, displayed a pattern of rapid fall germination identical to that of the sediment treatments. No consistent effect of light and dark treatments was observed in the water-column seeds. We conclude that eelgrass seeds are well adapted for germination in anoxic conditions and that seed germination in this region is keyed to not only seasonal temperature changes, but also oxygen availability. © 1993.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Moore, Kenneth A. and Orth, Robert J. and Nowak, Judith F.},\n\tyear = {1993},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The effects of light, oxygen and sediment burial on seed germination of Zostera marina L. were tested in two experiments beginning in 1987 and 1988. In 1987, seeds were placed in flow-through clear plastic tubes or buried at depths of 5, 15 and 25 mm in pots filled with seagrass sediments and held in an outdoor running seawater tank at ambient temperature, salinity and solar irradiance. The seeds began germinating in the sediments when water temperatures dropped to 15°C in mid-October and nearly all were germinated by December. Seeds held in the plastic tubes did not begin to germinate until mid-January. Again in 1988, seeds planted in pots germinated in October when temperatures decreased to 15°C; germination in the oxygenated water column was again delayed throughout the autumn and winter. However, seeds held in the water column in clear vials of deoxygenated water, without sediment, displayed a pattern of rapid fall germination identical to that of the sediment treatments. No consistent effect of light and dark treatments was observed in the water-column seeds. We conclude that eelgrass seeds are well adapted for germination in anoxic conditions and that seed germination in this region is keyed to not only seasonal temperature changes, but also oxygen availability. © 1993.\n
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\n \n\n \n \n \n \n \n Water quality associated with survival of submersed aquatic vegetation along an estuarine gradient.\n \n \n \n\n\n \n Court Stevenson, J.; Staver, L. W.; and Staver, K. W.\n\n\n \n\n\n\n Estuaries. 1993.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{court_stevenson_water_1993,\n\ttitle = {Water quality associated with survival of submersed aquatic vegetation along an estuarine gradient},\n\tdoi = {10.2307/1352507},\n\tabstract = {The decline of submersed aquatic vegetation (SAV) in tributaries of the Chesapeake Bay has been associated with increasing anthropogenic inputs, and restoration of the bay remains a major goal of the present multi-state "Bay Cleanup" effort. In order to determine SAV response to water quality, we quantified the water column parameters associated with success of transplants and natural regrowth over a three-year period along an estuarine gradient in the Choptank River, a major tributary on the eastern shore of Chesapeake Bay. The improvement in water quality due to low precipitation and low nonpoint source loadings during 1985-1988 provided a natural experiment in which SAV was able to persist upstream where it had not been for almost a decade. Mean water quality parameters were examined during the growing season (May-October) at 14 sites spanning the estuarine gradient and arrayed to show correspondence with the occurrence of SAV. Regrowth of SAV in the Choptank is associated with mean dissolved inorganic nitrogen {\\textbackslash}textless10 ��M; mean dissolved phosphate {\\textbackslash}textless0.35 μM; mean suspended sediment {\\textbackslash}textless20 mg l-1; mean chlorophyll a in the water column {\\textbackslash}textless15 μg l-1; and mean light attenuation coefficient (Kd) {\\textbackslash}textless2 m-1. These values correspond well with those derived in other parts of the Chesapeake, particularly in the lower bay, and may provide managers with values that can be used as target concentrations for nutrient reduction strategies where SAV is an issue. © 1993 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Court Stevenson, J. and Staver, Lorie W. and Staver, Kenneth W.},\n\tyear = {1993},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The decline of submersed aquatic vegetation (SAV) in tributaries of the Chesapeake Bay has been associated with increasing anthropogenic inputs, and restoration of the bay remains a major goal of the present multi-state \"Bay Cleanup\" effort. In order to determine SAV response to water quality, we quantified the water column parameters associated with success of transplants and natural regrowth over a three-year period along an estuarine gradient in the Choptank River, a major tributary on the eastern shore of Chesapeake Bay. The improvement in water quality due to low precipitation and low nonpoint source loadings during 1985-1988 provided a natural experiment in which SAV was able to persist upstream where it had not been for almost a decade. Mean water quality parameters were examined during the growing season (May-October) at 14 sites spanning the estuarine gradient and arrayed to show correspondence with the occurrence of SAV. Regrowth of SAV in the Choptank is associated with mean dissolved inorganic nitrogen \\textless10 ��M; mean dissolved phosphate \\textless0.35 μM; mean suspended sediment \\textless20 mg l-1; mean chlorophyll a in the water column \\textless15 μg l-1; and mean light attenuation coefficient (Kd) \\textless2 m-1. These values correspond well with those derived in other parts of the Chesapeake, particularly in the lower bay, and may provide managers with values that can be used as target concentrations for nutrient reduction strategies where SAV is an issue. © 1993 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Relative effects of nutrient enrichment and grazing on epiphyte-macrophyte (Zostera marina L.) dynamics.\n \n \n \n\n\n \n Neckles, H. A.; Wetzel, R. L.; and Orth, R. J.\n\n\n \n\n\n\n Oecologia. 1993.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{neckles_relative_1993,\n\ttitle = {Relative effects of nutrient enrichment and grazing on epiphyte-macrophyte ({Zostera} marina {L}.) dynamics},\n\tdoi = {10.1007/BF00317683},\n\tabstract = {The independent and interactive effects of nutrient concentration and epiphyte grazers on epiphyte biomass and macrophyte growth and production were examined in Zostera marina L. (eelgrass) microcosms. Experiments were conducted during early summer, late summer, fall, and spring in a greenhouse on the York River estuary of Chesapeake Bay. Nutrient treatments consisted of ambient or enriched (3× ambient) concentrations of inorganic nitrogen (ammonium nitrate) and phosphate. Grazer treatments consisted of the presence or absence of field densities of isopods, amphipods, and gastropods. epiphyte biomass increased with both grazer removal and nutrient enrichment during summer and spring experiments. The effect of grazers was stronger than that of nutrients. There was little epiphyte response to treatment during the fall, a result possibly of high ambient nutrient concentrations and low grazing pressure. Under low grazer densities of early summer, macrophyte production (g m-2 d-1) was reduced by grazer removal and nutrient enrichment independently. Under high grazer densities of late summer, macrophyte production was reduced by enrichment only with grazers absent. During spring and fall there were no macrophyte responses to treatment. The relative influence of epiphytes on macrophyte production may have been related to seasonally changing water temperature and macrophyte requirements for light and inorganic carbon. © 1993 Springer-Verlag.},\n\tjournal = {Oecologia},\n\tauthor = {Neckles, Hilary A. and Wetzel, Richard L. and Orth, Robert J.},\n\tyear = {1993},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The independent and interactive effects of nutrient concentration and epiphyte grazers on epiphyte biomass and macrophyte growth and production were examined in Zostera marina L. (eelgrass) microcosms. Experiments were conducted during early summer, late summer, fall, and spring in a greenhouse on the York River estuary of Chesapeake Bay. Nutrient treatments consisted of ambient or enriched (3× ambient) concentrations of inorganic nitrogen (ammonium nitrate) and phosphate. Grazer treatments consisted of the presence or absence of field densities of isopods, amphipods, and gastropods. epiphyte biomass increased with both grazer removal and nutrient enrichment during summer and spring experiments. The effect of grazers was stronger than that of nutrients. There was little epiphyte response to treatment during the fall, a result possibly of high ambient nutrient concentrations and low grazing pressure. Under low grazer densities of early summer, macrophyte production (g m-2 d-1) was reduced by grazer removal and nutrient enrichment independently. Under high grazer densities of late summer, macrophyte production was reduced by enrichment only with grazers absent. During spring and fall there were no macrophyte responses to treatment. The relative influence of epiphytes on macrophyte production may have been related to seasonally changing water temperature and macrophyte requirements for light and inorganic carbon. © 1993 Springer-Verlag.\n
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\n \n\n \n \n \n \n \n Nitrogen versus phosphorus enrichment of brackish waters: responses of the submersed plant Potamogeton perfoliatus and its associated algal community.\n \n \n \n\n\n \n Neundorfer, J. V.; and Kemp, W. M.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1993.\n \n\n\n\n
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@article{neundorfer_nitrogen_1993,\n\ttitle = {Nitrogen versus phosphorus enrichment of brackish waters: responses of the submersed plant {Potamogeton} perfoliatus and its associated algal community},\n\tdoi = {10.3354/meps094071},\n\tabstract = {Potamogeton perfoliatus was formerly an abundant component of brackish waters of Chesapeake Bay prior to a general decline in submersed plants associated with eutrophication. Additions of both N and P caused significant increases in biomass accumulation of epiphytic and phytoplanktonic communities. The effects of N and P on algal densities were synergistic in that responses to N addition were greatest at high P loading and vice versa. At the highest nutrient treatment rates, combined amendments (N plus P) resulted in significantly greater increases in epiphytes and phytoplankton than did the same high inputs of either nutrient (N or P) individually. Associated with increased algal densities at high nutrient loading rates, there were significant decreases in growth and biomass of P. perfoliatus. Significant inverse correlations were found between epiphyte density and plant growth and biomass as well as light attenuation. Management efforts to restore submersed plants such as P. perfoliatus by reducing eutrophication, and associated light attenuation by algae, should consider reducing inputs of both N and P. -from Authors},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Neundorfer, J. V. and Kemp, W. M.},\n\tyear = {1993},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Potamogeton perfoliatus was formerly an abundant component of brackish waters of Chesapeake Bay prior to a general decline in submersed plants associated with eutrophication. Additions of both N and P caused significant increases in biomass accumulation of epiphytic and phytoplanktonic communities. The effects of N and P on algal densities were synergistic in that responses to N addition were greatest at high P loading and vice versa. At the highest nutrient treatment rates, combined amendments (N plus P) resulted in significantly greater increases in epiphytes and phytoplankton than did the same high inputs of either nutrient (N or P) individually. Associated with increased algal densities at high nutrient loading rates, there were significant decreases in growth and biomass of P. perfoliatus. Significant inverse correlations were found between epiphyte density and plant growth and biomass as well as light attenuation. Management efforts to restore submersed plants such as P. perfoliatus by reducing eutrophication, and associated light attenuation by algae, should consider reducing inputs of both N and P. -from Authors\n
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\n \n\n \n \n \n \n \n Influence of the submersed plant, Potamogeton perfoliatus, on nitrogen cycling in estuarine sediments.\n \n \n \n\n\n \n Cufrey, J. M.; and Kemp, W. M.\n\n\n \n\n\n\n Limnology and Oceanography. 1992.\n \n\n\n\n
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@article{cufrey_influence_1992,\n\ttitle = {Influence of the submersed plant, {Potamogeton} perfoliatus, on nitrogen cycling in estuarine sediments},\n\tdoi = {10.4319/lo.1992.37.7.1483},\n\tabstract = {This article is in Free Access Publication and may be downloaded using the “Download Full Text PDF” link at right. © 1992, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Cufrey, Jane M. and Kemp, W. Michael},\n\tyear = {1992},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n This article is in Free Access Publication and may be downloaded using the “Download Full Text PDF” link at right. © 1992, by the Association for the Sciences of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Tidal mass exchange between a submersed aquatic vegetation bed and the main channel of the Potomac River.\n \n \n \n\n\n \n Jenter, H. L.; Rybicki, N. B.; Baltzer, R. A.; and Carter, V.\n\n\n \n\n\n\n In Proceedings - National Conference on Hydraulic Engineering, 1991. \n \n\n\n\n
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@inproceedings{jenter_tidal_1991,\n\ttitle = {Tidal mass exchange between a submersed aquatic vegetation bed and the main channel of the {Potomac} {River}},\n\tisbn = {0-87262-816-7},\n\tabstract = {Tidal mass exchange between a submersed aquatic vegetation (SAV) bed and the main channel of the Potomac River was investigated. Water levels were recorded at 5 minute intervals from August (when plants were present) through December (when plants were absent). Velocities were measured during individual tidal cycles both in the presence and absence of plants. Flow patterns were found to be altered significantly when plants were present. SAV impeded flow onto the shoal causing a water level phase lag between the bed and the channel, a reduction in flow speed and a change in flow direction. The phase lag was enhanced when the low frequency (subtidal) water level in the channel was below normal. The phase lag was further enhanced during spring tides. Ebb flow in the presence of plants was perpendicular to the edge of the SAV bed in the direction of the pressure gradient established by the lagging water level. Flood flow did not follow such a predictable pattern despite the strongest pressure gradients occurring during flood tides. In the absence of plants the flow speed increased by nearly an order of magnitude and the water-level phase lag disappeared.},\n\tbooktitle = {Proceedings - {National} {Conference} on {Hydraulic} {Engineering}},\n\tauthor = {Jenter, Harry L. and Rybicki, Nancy B. and Baltzer, Robert A. and Carter, Virginia},\n\tyear = {1991},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Tidal mass exchange between a submersed aquatic vegetation (SAV) bed and the main channel of the Potomac River was investigated. Water levels were recorded at 5 minute intervals from August (when plants were present) through December (when plants were absent). Velocities were measured during individual tidal cycles both in the presence and absence of plants. Flow patterns were found to be altered significantly when plants were present. SAV impeded flow onto the shoal causing a water level phase lag between the bed and the channel, a reduction in flow speed and a change in flow direction. The phase lag was enhanced when the low frequency (subtidal) water level in the channel was below normal. The phase lag was further enhanced during spring tides. Ebb flow in the presence of plants was perpendicular to the edge of the SAV bed in the direction of the pressure gradient established by the lagging water level. Flood flow did not follow such a predictable pattern despite the strongest pressure gradients occurring during flood tides. In the absence of plants the flow speed increased by nearly an order of magnitude and the water-level phase lag disappeared.\n
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\n \n\n \n \n \n \n \n Seasonal and spatial patterns of oxygen production, respiration and root-rhizome release in Potamogeton perfoliatus L. and Zostera marina L.\n \n \n \n\n\n \n Caffrey, J. M.; and Kemp, W. M.\n\n\n \n\n\n\n Aquatic Botany. 1991.\n \n\n\n\n
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\n 
@article{caffrey_seasonal_1991,\n\ttitle = {Seasonal and spatial patterns of oxygen production, respiration and root-rhizome release in {Potamogeton} perfoliatus {L}. and {Zostera} marina {L}.},\n\tdoi = {10.1016/0304-3770(91)90090-R},\n\tabstract = {Oxygen release to the rhizosphere was measured in situ with O2 microelectrodes and in hydroponic, split-compartment chambers. Light-dark experiments revealed that O2 release from the rhizomes of Potamogeton perfoliatus L. was directly dependent on photosynthesis and that O2 concentrations in sediments near the rhizomes started to decrease within 2 min after plants were darkened. Using Fick's first law of diffusion, the calculated net O2 flux in P. perfoliatus was approximately 120 μmol g-1 dry weight h-1, similar to fluxes calculated from hydroponic measurements. Root-rhizome O2 release, photosynthesis and respiration were measured for P. perfoliatus and Zostera marina L., with split-compartment hydroponic chambers in spring, summer and fall. For Z. marina, variability of root-rhizome O2 release, photosynthesis and respiration were observed between different sites within an eelgrass bed. The highest rates of O2 release from roots and rhizomes occurred in spring for both species and declined during the summer. For P. perfoliatus, the shortest plants ({\\textbackslash}textless 10 cm stem length) had the highest O2 release, about 43 μmol g-1 dry weight h-1. Root-rhizome O2 release was significantly related to photosynthesis only for P. perfoliatus. Oxidation of the rhizosphere depended on root-rhizome O2 release and biomass, which changed seasonally. Although weight-specific release rates were higher for P. perfoliatus than Z. marina, the potential oxidation of the rhizosphere was similar for both species (approximately 4-6 mmol O2 m-2 h-1) because of relatively high Z. marina root and rhizome biomass. © 1991.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Caffrey, J. M. and Kemp, W. M.},\n\tyear = {1991},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Oxygen release to the rhizosphere was measured in situ with O2 microelectrodes and in hydroponic, split-compartment chambers. Light-dark experiments revealed that O2 release from the rhizomes of Potamogeton perfoliatus L. was directly dependent on photosynthesis and that O2 concentrations in sediments near the rhizomes started to decrease within 2 min after plants were darkened. Using Fick's first law of diffusion, the calculated net O2 flux in P. perfoliatus was approximately 120 μmol g-1 dry weight h-1, similar to fluxes calculated from hydroponic measurements. Root-rhizome O2 release, photosynthesis and respiration were measured for P. perfoliatus and Zostera marina L., with split-compartment hydroponic chambers in spring, summer and fall. For Z. marina, variability of root-rhizome O2 release, photosynthesis and respiration were observed between different sites within an eelgrass bed. The highest rates of O2 release from roots and rhizomes occurred in spring for both species and declined during the summer. For P. perfoliatus, the shortest plants (\\textless 10 cm stem length) had the highest O2 release, about 43 μmol g-1 dry weight h-1. Root-rhizome O2 release was significantly related to photosynthesis only for P. perfoliatus. Oxidation of the rhizosphere depended on root-rhizome O2 release and biomass, which changed seasonally. Although weight-specific release rates were higher for P. perfoliatus than Z. marina, the potential oxidation of the rhizosphere was similar for both species (approximately 4-6 mmol O2 m-2 h-1) because of relatively high Z. marina root and rhizome biomass. © 1991.\n
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\n \n\n \n \n \n \n \n Effects of submersed macrophytes on dissolved oxygen, pH, and temperature under different conditions of wind, tide, and bed structure.\n \n \n \n\n\n \n Carter, V.; Rybicki, N. B.; and Hammerschlag, R.\n\n\n \n\n\n\n Journal of Freshwater Ecology. 1991.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{carter_effects_1991,\n\ttitle = {Effects of submersed macrophytes on dissolved oxygen, {pH}, and temperature under different conditions of wind, tide, and bed structure},\n\tdoi = {10.1080/02705060.1991.9665286},\n\tabstract = {Seasonal data on diurnal dissolved-oxygen concentration (DO), pH, temperature and chlorophyll-a were collected and species composition and vertical structure of macrophyte beds were analyzed in the tidal Potomac River during the 1987 growing season. The relationships among these variables and physical and climatic factors were analyzed. Elevated surface temperatures, DO and pH were found in macrophyte beds in June and August; surface temperatures were also elevated in the dense Hydrilla verticillata dominated bed in October-November after senescence had begun. Bottom DO, pH and temperature were lower than surface values. Bottom temperatures in vegetated sites were highly variable compared with bottom temperatures in unvegetated sites. Tide, wind, vegetative structure and available sunshine interacted in a complex fashion to control the magnitude of the diurnal DO, pH and temperature and the stratification of DO, pH and temperature with depth in vegetated sites. Fluctuations in DO and pH at unvegetated sites were the result of phytoplankton photosynthesis and proximity to beds of vegetation as well as wind and available sunshine. The tidal cycle drove the daily exchange of water between macrophyte beds and adjacent water. © Taylor \\& Francis Group, LLC.},\n\tjournal = {Journal of Freshwater Ecology},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B. and Hammerschlag, Richard},\n\tyear = {1991},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Seasonal data on diurnal dissolved-oxygen concentration (DO), pH, temperature and chlorophyll-a were collected and species composition and vertical structure of macrophyte beds were analyzed in the tidal Potomac River during the 1987 growing season. The relationships among these variables and physical and climatic factors were analyzed. Elevated surface temperatures, DO and pH were found in macrophyte beds in June and August; surface temperatures were also elevated in the dense Hydrilla verticillata dominated bed in October-November after senescence had begun. Bottom DO, pH and temperature were lower than surface values. Bottom temperatures in vegetated sites were highly variable compared with bottom temperatures in unvegetated sites. Tide, wind, vegetative structure and available sunshine interacted in a complex fashion to control the magnitude of the diurnal DO, pH and temperature and the stratification of DO, pH and temperature with depth in vegetated sites. Fluctuations in DO and pH at unvegetated sites were the result of phytoplankton photosynthesis and proximity to beds of vegetation as well as wind and available sunshine. The tidal cycle drove the daily exchange of water between macrophyte beds and adjacent water. © Taylor & Francis Group, LLC.\n
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\n \n\n \n \n \n \n \n An overview of atrazine dynamics in estuarine ecosystems.\n \n \n \n\n\n \n Stevenson, J C; Jones, T W; Kemp, W M; Boynton, W R; and Means, J C\n\n\n \n\n\n\n 1990.\n Publication Title: \\textlessNone Specified\\textgreater\n\n\n\n
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@book{stevenson_overview_1990,\n\ttitle = {An overview of atrazine dynamics in estuarine ecosystems},\n\tabstract = {Atrazine, one of the s-trizaine compounds, is the most extensively used herbicide in the United States. The potential significance of this herbicide as stress in estuarine ecosystems in considered in terms of its toxicity for animals and plants. Although quantities less than 1 ppm do not exert significant direct effects on animals, atrazine is much more toxic to plant species and thus potentially a problem in estuarine ecosystems especially to submerged aquatic vegetation.},\n\tauthor = {Stevenson, J C and Jones, T W and Kemp, W M and Boynton, W R and Means, J C},\n\tyear = {1990},\n\tnote = {Publication Title: {\\textbackslash}textlessNone Specified{\\textbackslash}textgreater},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Atrazine, one of the s-trizaine compounds, is the most extensively used herbicide in the United States. The potential significance of this herbicide as stress in estuarine ecosystems in considered in terms of its toxicity for animals and plants. Although quantities less than 1 ppm do not exert significant direct effects on animals, atrazine is much more toxic to plant species and thus potentially a problem in estuarine ecosystems especially to submerged aquatic vegetation.\n
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\n \n\n \n \n \n \n \n Light attenuation and submersed macrophyte distribution in the tidal Potomac River and estuary.\n \n \n \n\n\n \n Carter, V.; and Rybicki, N. B.\n\n\n \n\n\n\n Estuaries. 1990.\n \n\n\n\n
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@article{carter_light_1990,\n\ttitle = {Light attenuation and submersed macrophyte distribution in the tidal {Potomac} {River} and estuary},\n\tdoi = {10.2307/1351788},\n\tabstract = {Changing light availability may be responsible for the discontinuous distribution of submersed aquatic macrophytes in the freshwater tidal Potomac River. During the 1985-1986 growing seasons, light attenuation and chlorophyll a and suspended particulate material concentrations were measured in an unvegetated reach (B) and in two adjacent vegetated reaches (A and C). Light attenuation in reach B (the lower, fresh to oligohaline tidal river) was greater than that in reach A (the recently revegetated, upper, freshwater tidal river) in both years. Reach B light attenuation was greater than that in reach C (the vegetated, oligohaline to mesohaline transition zone of the Potomac Estuary) in 1985 and similar to that in reach C in 1986. In reach B, 5\\% of total below-surface light penetrated only an average of 1.3 m in 1985 and 1.0m in 1986, compared with 1.9 m and 1.4 m in reach A in 1985 and 1986, respectively. Water column chlorophyll a concentration controlled light availability in reaches A and B in 1985, whereas both chlorophyll a and suspended particulate material concentrations were highly correlated with attenuation in both reaches in 1986. Reach C light attenuation was correlated with suspended particulate material in 1986. The relationship between attenuation coefficient and Secchi depth was KPAR=1.38/Secchi depth. The spectral distribution of light at 1 m was shifted toward the red portion of the visible spectrum compared to surface light. Blue light was virtually absent at 1.0 m in reach B during July and August 1986. Tidal range is probably an important factor in determining light availability for submersed macrophyte propagule survival at the sediment-water interface in this shallow turbid system. © 1990 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B.},\n\tyear = {1990},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Changing light availability may be responsible for the discontinuous distribution of submersed aquatic macrophytes in the freshwater tidal Potomac River. During the 1985-1986 growing seasons, light attenuation and chlorophyll a and suspended particulate material concentrations were measured in an unvegetated reach (B) and in two adjacent vegetated reaches (A and C). Light attenuation in reach B (the lower, fresh to oligohaline tidal river) was greater than that in reach A (the recently revegetated, upper, freshwater tidal river) in both years. Reach B light attenuation was greater than that in reach C (the vegetated, oligohaline to mesohaline transition zone of the Potomac Estuary) in 1985 and similar to that in reach C in 1986. In reach B, 5% of total below-surface light penetrated only an average of 1.3 m in 1985 and 1.0m in 1986, compared with 1.9 m and 1.4 m in reach A in 1985 and 1986, respectively. Water column chlorophyll a concentration controlled light availability in reaches A and B in 1985, whereas both chlorophyll a and suspended particulate material concentrations were highly correlated with attenuation in both reaches in 1986. Reach C light attenuation was correlated with suspended particulate material in 1986. The relationship between attenuation coefficient and Secchi depth was KPAR=1.38/Secchi depth. The spectral distribution of light at 1 m was shifted toward the red portion of the visible spectrum compared to surface light. Blue light was virtually absent at 1.0 m in reach B during July and August 1986. Tidal range is probably an important factor in determining light availability for submersed macrophyte propagule survival at the sediment-water interface in this shallow turbid system. © 1990 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Nitrogen cycling in sediments with estuarine populations of Potamogeton perfoliatus and Zostera marina.\n \n \n \n\n\n \n Caffrey, J.; and Kemp, W.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1990.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{caffrey_nitrogen_1990,\n\ttitle = {Nitrogen cycling in sediments with estuarine populations of {Potamogeton} perfoliatus and {Zostera} marina},\n\tdoi = {10.3354/meps066147},\n\tabstract = {Rates of nitrogen transformations and concentrations of extractable NH4+ and NO3- (plus NO2-) were measured in estuarine sediments vegetated with the submersed macrophytes Potamogeton perfoliatus and Zostera marina, and in adjacent bare sediments, 3 or 4 times during the growing season. Nitrification and denitrification potentials were measured in substrated-amended sediment slurries at 5 depth intervals to provide a measure of bacterial activity. In general, rates were significantly higher in vegetated compared to bare sediments. It appears that both plant species affected nitrogen transformations through several similar mechanisms, while the microbial community, in turn, regulated nitrogen available for plant growth. In P. perfoliatus beds, ammonification and potential nitrification rates were correlated. Both exhibited summer maxima coinciding with peak plant biomass and productivity. Although vertically integrated (0-12 cm) ammonification rates were about twice as high in vegetated than in bare sediments, NH4+ pools were significantly lower, probably due to high plant nitrogen demand. In contrast, denitrification rates were highest in spring when NO3- concentrations peaked, and were significantly correlated to nitrification rates in both spring and fall. Denitrification was only about 20\\% of total NO3- reduction, suggesting that NH4+ production from NO3- may be important in conserving nitrogen within the grassbed. In sediments with Z. marina, rates of ammonification, and nitrification and denitrification potentials each exhibited a distinct seasonal cycle, indicating that rates were not as tightly coupled as in P. perfoliatus beds. High ammonification rates exceeded plant demand leading to NH4+ accumulation. Potential nitrification rates were highest in vegetated sediments during fall. Denitrification rates, which were also greater in vegetated than in bare sediments, were highest in spring when NO3- concentrations were high. Potential denitrification rates comprised about 10\\% of total NO3- reduction, indicating that NO3- reduction to NH4+ dominated. The microbial communities responsible for key nitrogen transformation in the sediments were enhanced by both P. perfoliatus and Z. marina ammonification by inputs of organic nitrogen; nitrification by release of O2 by plant roots; and denitrification by production of NO3-.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Caffrey, JM and Kemp, WM},\n\tyear = {1990},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Rates of nitrogen transformations and concentrations of extractable NH4+ and NO3- (plus NO2-) were measured in estuarine sediments vegetated with the submersed macrophytes Potamogeton perfoliatus and Zostera marina, and in adjacent bare sediments, 3 or 4 times during the growing season. Nitrification and denitrification potentials were measured in substrated-amended sediment slurries at 5 depth intervals to provide a measure of bacterial activity. In general, rates were significantly higher in vegetated compared to bare sediments. It appears that both plant species affected nitrogen transformations through several similar mechanisms, while the microbial community, in turn, regulated nitrogen available for plant growth. In P. perfoliatus beds, ammonification and potential nitrification rates were correlated. Both exhibited summer maxima coinciding with peak plant biomass and productivity. Although vertically integrated (0-12 cm) ammonification rates were about twice as high in vegetated than in bare sediments, NH4+ pools were significantly lower, probably due to high plant nitrogen demand. In contrast, denitrification rates were highest in spring when NO3- concentrations peaked, and were significantly correlated to nitrification rates in both spring and fall. Denitrification was only about 20% of total NO3- reduction, suggesting that NH4+ production from NO3- may be important in conserving nitrogen within the grassbed. In sediments with Z. marina, rates of ammonification, and nitrification and denitrification potentials each exhibited a distinct seasonal cycle, indicating that rates were not as tightly coupled as in P. perfoliatus beds. High ammonification rates exceeded plant demand leading to NH4+ accumulation. Potential nitrification rates were highest in vegetated sediments during fall. Denitrification rates, which were also greater in vegetated than in bare sediments, were highest in spring when NO3- concentrations were high. Potential denitrification rates comprised about 10% of total NO3- reduction, indicating that NO3- reduction to NH4+ dominated. The microbial communities responsible for key nitrogen transformation in the sediments were enhanced by both P. perfoliatus and Z. marina ammonification by inputs of organic nitrogen; nitrification by release of O2 by plant roots; and denitrification by production of NO3-.\n
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\n \n\n \n \n \n \n \n Aspects of nitrogen acquisition and conservation in eelgrass plants.\n \n \n \n\n\n \n Borum, J.; Murray, L.; and Michael Kemp, W.\n\n\n \n\n\n\n Aquatic Botany. 1989.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{borum_aspects_1989,\n\ttitle = {Aspects of nitrogen acquisition and conservation in eelgrass plants},\n\tdoi = {10.1016/0304-3770(89)90003-X},\n\tabstract = {Eelgrass (Zostera marina L.) collected in the field was analysed for nitrogen content in different tissues. Cultured eelgrass plants were pre-incubated with 15NNH4+ (90 μmol NH4+ 1-1) and subsequently incubated in enriched seawater (50 μmol NH4+ 1-1) with ambient at.\\% 15N in order to follow changes in nitrogen content and translocation among different plant tissues in relation to growth. The average N content in plants collected in the field was 1.6\\% of dry weight (DW), indicating N limitation of growth. When exposed to high N availability in the water column the N uptake by the plants both fulfilled requirements for growth and allowed accumulation of surplus nitrogen. After two weeks of incubation average N content in whole plants was 2.5\\% of DW. The rate of N uptake in leaves was independent of leaf age, but N was translocated from old leaves to the youngest and most actively growing tissues resulting in higher N accumulation in these tissues. The N content declined with increasing leaf age. Leakage to the external medium played a minor role since more than 90\\% of the N lost from old leaves was recovered in other plant parts. Translocation of N from old leaves accounted for most of the N accumulation in actively growing tissues despite the high N availability in the external medium. The distribution of N within different plant parts and the observed translocation pattern indicate that nitrogen reclamation in eelgrass reduces the plant's dependence on external nitrogen sources. © 1989.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Borum, Jens and Murray, Laura and Michael Kemp, W.},\n\tyear = {1989},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Eelgrass (Zostera marina L.) collected in the field was analysed for nitrogen content in different tissues. Cultured eelgrass plants were pre-incubated with 15NNH4+ (90 μmol NH4+ 1-1) and subsequently incubated in enriched seawater (50 μmol NH4+ 1-1) with ambient at.% 15N in order to follow changes in nitrogen content and translocation among different plant tissues in relation to growth. The average N content in plants collected in the field was 1.6% of dry weight (DW), indicating N limitation of growth. When exposed to high N availability in the water column the N uptake by the plants both fulfilled requirements for growth and allowed accumulation of surplus nitrogen. After two weeks of incubation average N content in whole plants was 2.5% of DW. The rate of N uptake in leaves was independent of leaf age, but N was translocated from old leaves to the youngest and most actively growing tissues resulting in higher N accumulation in these tissues. The N content declined with increasing leaf age. Leakage to the external medium played a minor role since more than 90% of the N lost from old leaves was recovered in other plant parts. Translocation of N from old leaves accounted for most of the N accumulation in actively growing tissues despite the high N availability in the external medium. The distribution of N within different plant parts and the observed translocation pattern indicate that nitrogen reclamation in eelgrass reduces the plant's dependence on external nitrogen sources. © 1989.\n
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\n \n\n \n \n \n \n \n Light responses of a submersed macrophyte: implications for survival in turbid tidal waters.\n \n \n \n\n\n \n Goldsborough, W. J.; and Kemp, W. M.\n\n\n \n\n\n\n Ecology. 1988.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{goldsborough_light_1988,\n\ttitle = {Light responses of a submersed macrophyte: implications for survival in turbid tidal waters},\n\tdoi = {10.2307/1941156},\n\tabstract = {Responses and acclimation of the submersed vascular plant Potamogeton perfoliatus to changes in total irradiance were investigated by growing replicate populations under 3 treatment levels (11, 32 and 100\\% of ambient). Significant morphological responses to and recovery from shade were evident within 10 d, including: elongation of stems, thinning of lower leaves, and canopy formation at the water surface. Both photosynthetic and morphological acclimations to shade conferred substantial improvements in P. perfoliatus production at experimentally reduced irradiance compared to pretreatment conditions. Significant decreases in plant stem density, biomass and reproduction, as well as increases in mortality, were observed for plants at low growth irradiance. The inability of populations treated at low irradiance to exhibit any recovery (posttreatment increases) in these variables after 16 d of full ambient light suggests that 11\\% of ambient irradiance was below the minimum level needed for survival of this plant. Although stem elongation is a beneficial response to shade for P. perfoliatus in turbid lakes, it may be nonadaptive in turbulent tidal waters because of increased susceptibility to fragmentation. -from Authors},\n\tjournal = {Ecology},\n\tauthor = {Goldsborough, W. J. and Kemp, W. M.},\n\tyear = {1988},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Responses and acclimation of the submersed vascular plant Potamogeton perfoliatus to changes in total irradiance were investigated by growing replicate populations under 3 treatment levels (11, 32 and 100% of ambient). Significant morphological responses to and recovery from shade were evident within 10 d, including: elongation of stems, thinning of lower leaves, and canopy formation at the water surface. Both photosynthetic and morphological acclimations to shade conferred substantial improvements in P. perfoliatus production at experimentally reduced irradiance compared to pretreatment conditions. Significant decreases in plant stem density, biomass and reproduction, as well as increases in mortality, were observed for plants at low growth irradiance. The inability of populations treated at low irradiance to exhibit any recovery (posttreatment increases) in these variables after 16 d of full ambient light suggests that 11% of ambient irradiance was below the minimum level needed for survival of this plant. Although stem elongation is a beneficial response to shade for P. perfoliatus in turbid lakes, it may be nonadaptive in turbulent tidal waters because of increased susceptibility to fragmentation. -from Authors\n
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\n \n\n \n \n \n \n \n Effects of submersed macrophytes on water quality in the tidal Potomac River, Maryland.\n \n \n \n\n\n \n Carter, V.; Barko, J. W.; Godshalk, G. L.; and Rybicki, N. B.\n\n\n \n\n\n\n Journal of Freshwater Ecology. 1988.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carter_effects_1988,\n\ttitle = {Effects of submersed macrophytes on water quality in the tidal {Potomac} {River}, {Maryland}},\n\tdoi = {10.1080/02705060.1988.9665199},\n\tabstract = {In August, 1986, diurnal measurements of temperature, conductivity, dissolved oxygen and pH, and tide-related measurements of suspended-particulate matter and chlorophyll-a were made at three stations within a dense macrophyte bed and at a fourth unvegetated station outside the bed. Light penetration and current velocity were measured at a hole within the bed and at the unvegetated station. Water temperature, dissolved oxygen and pH increased during the day with the steepest vertical gradients and maximum readings occurring within the bed during midafternoon at low tide. Current velocities within the beds were about one-third of those at the open-water site and water clarity was considerably greater inside the bed. Chlorophyll-a and suspended-particulate concentrations were significantly lower at vegetated stations than at the unvegetated open-water station. © 1988 by Oikos Publishers, Inc.},\n\tjournal = {Journal of Freshwater Ecology},\n\tauthor = {Carter, Virginia and Barko, John W. and Godshalk, G. L. and Rybicki, Nancy B.},\n\tyear = {1988},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n In August, 1986, diurnal measurements of temperature, conductivity, dissolved oxygen and pH, and tide-related measurements of suspended-particulate matter and chlorophyll-a were made at three stations within a dense macrophyte bed and at a fourth unvegetated station outside the bed. Light penetration and current velocity were measured at a hole within the bed and at the unvegetated station. Water temperature, dissolved oxygen and pH increased during the day with the steepest vertical gradients and maximum readings occurring within the bed during midafternoon at low tide. Current velocities within the beds were about one-third of those at the open-water site and water clarity was considerably greater inside the bed. Chlorophyll-a and suspended-particulate concentrations were significantly lower at vegetated stations than at the unvegetated open-water station. © 1988 by Oikos Publishers, Inc.\n
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\n \n\n \n \n \n \n \n Diel growth in eelgrass Zostera marina.\n \n \n \n\n\n \n Kemp, W.; Murray, L; Borum, J; and Sand-Jensen, K\n\n\n \n\n\n\n Marine Ecology Progress Series. 1987.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{kemp_diel_1987,\n\ttitle = {Diel growth in eelgrass {Zostera} marina},\n\tdoi = {10.3354/meps041079},\n\tabstract = {Growth of eelgrass Zostera marina leaves was determined by sequential measurements of leaf length at time intervals of 4 to 12 h. Leaf growth rates at night were consistently lower (30 to 40\\%) compared to daytime rates, and night-time rates were highly correlated with growth during the previous day. Diel patterns of O sub(2) metabolism (measured at 2 to 4 h intervals) and leaf growth (at 4 h intervals) generally followed the daily irradiance cycle, with maximum growth and O sub(2) production rates both occurring near midday. It was demonstrated, however, that separate calibration studies relating root-rhizome growth to leaf growth can be conducted (over 1 to 2 wk) to allow estimates of short-term (4 to 12 h) responses of total plant growth to changes in environmental conditions.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Kemp, WM and Murray, L and Borum, J and Sand-Jensen, K},\n\tyear = {1987},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Growth of eelgrass Zostera marina leaves was determined by sequential measurements of leaf length at time intervals of 4 to 12 h. Leaf growth rates at night were consistently lower (30 to 40%) compared to daytime rates, and night-time rates were highly correlated with growth during the previous day. Diel patterns of O sub(2) metabolism (measured at 2 to 4 h intervals) and leaf growth (at 4 h intervals) generally followed the daily irradiance cycle, with maximum growth and O sub(2) production rates both occurring near midday. It was demonstrated, however, that separate calibration studies relating root-rhizome growth to leaf growth can be conducted (over 1 to 2 wk) to allow estimates of short-term (4 to 12 h) responses of total plant growth to changes in environmental conditions.\n
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\n \n\n \n \n \n \n \n A model of Zostera marina L. Photosynthesis and growth: Simulated effects of selected physical-chemical variables and biological interactions.\n \n \n \n\n\n \n Wetzel, R. L.; and Neckles, H. A.\n\n\n \n\n\n\n Aquatic Botany. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{wetzel_model_1986,\n\ttitle = {A model of {Zostera} marina {L}. {Photosynthesis} and growth: {Simulated} effects of selected physical-chemical variables and biological interactions},\n\tdoi = {10.1016/0304-3770(86)90029-X},\n\tabstract = {A computer model was developed to simulate photosynthesis and growth of eelgrass (Zostera marina L.), the dominant submerged aquatic macrophyte occurring in the lower Chesapeake Bay, Virginia, U.S.A. The mathematical structure of the model is based on theoretical non-linear functions for simulating biologically controlled processes and empirical or statistical relationships for incorporating physical-chemical interactions and environmental forcing functions. Analyses of the model for 1-, 4- and 10-year simulation periods indicate that submarine light quantity (PAR) and temperature are the principal physical factors governing eelgrass photosynthesis and growth in the lower Chesapeake Bay. Typical in situ light and temperature conditions, however, constrain photosynthesis and therefore plant growth to less than physiologically capable potentials. Small changes in submarine irradiance, temperature or their combined interaction result in decreased plant productivity and eventual loss of the eelgrass community. Empirical and hypothetical relationships in the model of epiphyte colonization and growth and epiphytic grazing indicate that eelgrass growth and long-term survival are potentially governed by factors that control and limit the attached epiphytic community. Model simulations suggest that a principal factor is the interaction between epiphytic grazing intensity and ambient light levels. © 1986.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Wetzel, Richard L. and Neckles, Hilary A.},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n A computer model was developed to simulate photosynthesis and growth of eelgrass (Zostera marina L.), the dominant submerged aquatic macrophyte occurring in the lower Chesapeake Bay, Virginia, U.S.A. The mathematical structure of the model is based on theoretical non-linear functions for simulating biologically controlled processes and empirical or statistical relationships for incorporating physical-chemical interactions and environmental forcing functions. Analyses of the model for 1-, 4- and 10-year simulation periods indicate that submarine light quantity (PAR) and temperature are the principal physical factors governing eelgrass photosynthesis and growth in the lower Chesapeake Bay. Typical in situ light and temperature conditions, however, constrain photosynthesis and therefore plant growth to less than physiologically capable potentials. Small changes in submarine irradiance, temperature or their combined interaction result in decreased plant productivity and eventual loss of the eelgrass community. Empirical and hypothetical relationships in the model of epiphyte colonization and growth and epiphytic grazing indicate that eelgrass growth and long-term survival are potentially governed by factors that control and limit the attached epiphytic community. Model simulations suggest that a principal factor is the interaction between epiphytic grazing intensity and ambient light levels. © 1986.\n
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\n \n\n \n \n \n \n \n A Comparative Study of Decomposition, Oxygen Consumption and Nutrient Release for Selected Aquatic Plants Occurring in an Estuarine Environment.\n \n \n \n\n\n \n Twilley, R. R.; Ejdung, G.; Romare, P.; and Kemp, W. M.\n\n\n \n\n\n\n Oikos. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{twilley_comparative_1986,\n\ttitle = {A {Comparative} {Study} of {Decomposition}, {Oxygen} {Consumption} and {Nutrient} {Release} for {Selected} {Aquatic} {Plants} {Occurring} in an {Estuarine} {Environment}},\n\tdoi = {10.2307/3566045},\n\tabstract = {Rates of decomposition and nutrient regeneration were compared among 6 aquatic plants representing examples from phytoplankton (Chlorella sp.), macroalgae (Ulva lactuca), submersed vascular macrophytes (Myriophyllum spicatum, Potamogeton perfoliatus, Ruppia maritima) and marsh grasses (Spartina alterniflora). -from Authors},\n\tjournal = {Oikos},\n\tauthor = {Twilley, Robert R. and Ejdung, Gunilla and Romare, Pia and Kemp, W. Michael},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Rates of decomposition and nutrient regeneration were compared among 6 aquatic plants representing examples from phytoplankton (Chlorella sp.), macroalgae (Ulva lactuca), submersed vascular macrophytes (Myriophyllum spicatum, Potamogeton perfoliatus, Ruppia maritima) and marsh grasses (Spartina alterniflora). -from Authors\n
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\n \n\n \n \n \n \n \n Atrazine uptake, photosynthetic inhibition, and short-term recovery for the submersed vascular plant, Potamogeton perfoliatus L.\n \n \n \n\n\n \n Jones, T. W.; Kemp, W. M.; Estes, P. S.; and Stevenson, J. C.\n\n\n \n\n\n\n Archives of Environmental Contamination and Toxicology. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{jones_atrazine_1986,\n\ttitle = {Atrazine uptake, photosynthetic inhibition, and short-term recovery for the submersed vascular plant, {Potamogeton} perfoliatus {L}.},\n\tdoi = {10.1007/BF01061104},\n\tabstract = {The processes of atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino-]-s-tri-azine) uptake and release in the submersed vascular plant, Potamogeton perfoliatus L., were rapid, approaching equilibrium with the surrounding environment within one hr. The ratio of internal atrazine concentration to external concentration was approximately 10 at the point of maximum photosynthetic inhibition and rapidly increased at lower external atrazine concentrations. The I50 (the concentration inhibiting photosynthesis by 50\\%) for atrazine in solution was 80 μg/L with the maximum observed photosynthetic reduction (87\\%) at a solution concentration of 650 μg/L. Initial photosynthetic recovery of P. perfoliatus following exposure to atrazine was rapid with oxygen evolution from treated plants (5, 25, and 100 μg/L) being statistically indistinguishable from control plants after two hr of atrazine-free wash. However, there was an indication of residual photosynthetic depression in dosed plants, even after a 77 hr recovery period. In Chesapeake Bay, potential long-term exposure of submersed plants to concentrations of atrazine greater than 10 μg/L is doubtful so that reduction of P. perfoliatus photosynthesis under such conditions would be minimal and reversible. © 1986 Springer-Verlag New York Inc.},\n\tjournal = {Archives of Environmental Contamination and Toxicology},\n\tauthor = {Jones, Thomas W. and Kemp, W. Michael and Estes, Patricia S. and Stevenson, J. Court},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The processes of atrazine (2-chloro-4-[ethylamino]-6-[isopropylamino-]-s-tri-azine) uptake and release in the submersed vascular plant, Potamogeton perfoliatus L., were rapid, approaching equilibrium with the surrounding environment within one hr. The ratio of internal atrazine concentration to external concentration was approximately 10 at the point of maximum photosynthetic inhibition and rapidly increased at lower external atrazine concentrations. The I50 (the concentration inhibiting photosynthesis by 50%) for atrazine in solution was 80 μg/L with the maximum observed photosynthetic reduction (87%) at a solution concentration of 650 μg/L. Initial photosynthetic recovery of P. perfoliatus following exposure to atrazine was rapid with oxygen evolution from treated plants (5, 25, and 100 μg/L) being statistically indistinguishable from control plants after two hr of atrazine-free wash. However, there was an indication of residual photosynthetic depression in dosed plants, even after a 77 hr recovery period. In Chesapeake Bay, potential long-term exposure of submersed plants to concentrations of atrazine greater than 10 μg/L is doubtful so that reduction of P. perfoliatus photosynthesis under such conditions would be minimal and reversible. © 1986 Springer-Verlag New York Inc.\n
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\n \n\n \n \n \n \n \n Effect of sediment depth and sediment type on the survival of Vallisneria americana Michx grown from tubers.\n \n \n \n\n\n \n Rybicki, N. B.; and Carter, V.\n\n\n \n\n\n\n Aquatic Botany. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{rybicki_effect_1986-1,\n\ttitle = {Effect of sediment depth and sediment type on the survival of {Vallisneria} americana {Michx} grown from tubers},\n\tdoi = {10.1016/0304-3770(86)90059-8},\n\tabstract = {Sedimentation resulting from storms may have been one of the reasons for the elimination of submersed aquatic vegetation from the tidal Potomac River in the late 1930's. Laboratory studies were conducted to investigate the effects of different depths of overlying sediment and composition of sediment on the survival of Vallisneria americana Michx (wildcelery) grown from tubers. Survival of plants grown from tubers decreased significantly with increasing sediment depth. Survival of tubers declined from 90\\% or more when buried in 10 cm to no survival in greater than 25 cm of sediment. Survival with depth in sand was significantly lower than in silty clay. Field investigation determined that the majority of tubers in Vallisneria beds are distributed between 10 and 20 cm in depth in silty clay and between 5 and 15 cm in depth in sand. Based on the field distribution of tubers and on the percent survival of plants growing from tubers at each depth in the laboratory experiment, we suggest that the deposition of 10 cm or more of sediment by severe storms such as occurred in the 1930s could contribute to the loss of vegetation in the tidal Potomac River. © 1986.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Rybicki, Nancy B. and Carter, Virginia},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Sedimentation resulting from storms may have been one of the reasons for the elimination of submersed aquatic vegetation from the tidal Potomac River in the late 1930's. Laboratory studies were conducted to investigate the effects of different depths of overlying sediment and composition of sediment on the survival of Vallisneria americana Michx (wildcelery) grown from tubers. Survival of plants grown from tubers decreased significantly with increasing sediment depth. Survival of tubers declined from 90% or more when buried in 10 cm to no survival in greater than 25 cm of sediment. Survival with depth in sand was significantly lower than in silty clay. Field investigation determined that the majority of tubers in Vallisneria beds are distributed between 10 and 20 cm in depth in silty clay and between 5 and 15 cm in depth in sand. Based on the field distribution of tubers and on the percent survival of plants growing from tubers at each depth in the laboratory experiment, we suggest that the deposition of 10 cm or more of sediment by severe storms such as occurred in the 1930s could contribute to the loss of vegetation in the tidal Potomac River. © 1986.\n
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\n \n\n \n \n \n \n \n Photosynthetic temperature acclimation in two coexisting seagrasses, Zostera marina L. and Ruppia maritima L.\n \n \n \n\n\n \n Evans, A. S.; Webb, K. L.; and Penhale, P. A.\n\n\n \n\n\n\n Aquatic Botany. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{evans_photosynthetic_1986,\n\ttitle = {Photosynthetic temperature acclimation in two coexisting seagrasses, {Zostera} marina {L}. and {Ruppia} maritima {L}.},\n\tdoi = {10.1016/0304-3770(86)90095-1},\n\tabstract = {The physiological responses to temperature were investigated in two coexisting seagrasses, Zostera marina L. and Ruppia maritima L. sensu lato from the lower Chesapeake Bay, Virginia. Seven plant collections were made from March to July, 1983 at ambient temperatures of 8-30°C. Both species maintained relatively constant fresh: dry weight ratios and chlorophyll a:b ratios over the five-month period. Total chlorophyll content remained constant in Z. marina while that of R. maritima doubled from March to July. Pmax values for both species increased with increasing temperature and declined at temperatures above 19 and 23°C (Z. marina and R. maritima, respectively). Pmax values were significantly higher for R. maritima compared to Z. marina at temperatures above 19°C. Both short-term (laboratory) and long-term (in situ) responses to temperature regimes affected estimates of the photosynthetic capacity of both species. Thus, temperature histories of experimental material should be carefully considered when interpreting temperature effects on photosynthesis. This study provides support of the hypothesis that seasonal community dynamics of Z. marina and R. maritima in Chesapeake Bay are regulated in part by different responses to light and temperature. © 1986.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Evans, Ann S. and Webb, Kenneth L. and Penhale, Polly A.},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The physiological responses to temperature were investigated in two coexisting seagrasses, Zostera marina L. and Ruppia maritima L. sensu lato from the lower Chesapeake Bay, Virginia. Seven plant collections were made from March to July, 1983 at ambient temperatures of 8-30°C. Both species maintained relatively constant fresh: dry weight ratios and chlorophyll a:b ratios over the five-month period. Total chlorophyll content remained constant in Z. marina while that of R. maritima doubled from March to July. Pmax values for both species increased with increasing temperature and declined at temperatures above 19 and 23°C (Z. marina and R. maritima, respectively). Pmax values were significantly higher for R. maritima compared to Z. marina at temperatures above 19°C. Both short-term (laboratory) and long-term (in situ) responses to temperature regimes affected estimates of the photosynthetic capacity of both species. Thus, temperature histories of experimental material should be carefully considered when interpreting temperature effects on photosynthesis. This study provides support of the hypothesis that seasonal community dynamics of Z. marina and R. maritima in Chesapeake Bay are regulated in part by different responses to light and temperature. © 1986.\n
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\n \n\n \n \n \n \n \n Oxygen release from roots of the submersed macrophyte Potamogeton perfoliatus L.: Regulating factors and ecological implications.\n \n \n \n\n\n \n Kemp, W. M.; and Murray, L.\n\n\n \n\n\n\n Aquatic Botany. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{kemp_oxygen_1986,\n\ttitle = {Oxygen release from roots of the submersed macrophyte {Potamogeton} perfoliatus {L}.: {Regulating} factors and ecological implications},\n\tdoi = {10.1016/0304-3770(86)90027-6},\n\tabstract = {Rates of photosynthetic production, respiratory consumption and root release of dissolved oxygen (O2) were measured for Potamogeton perfoliatus L. from an estuarine population. Incubations were conducted in split-compartment chambers, with shoots (leaves and stems) separated from roots (plus rhizomes). Time-course observations of O2 exchanges between plants and filtered estuarine water were made at ambient temperatures in natural daylight and in darkness. Release of oxygen from roots (Lr) to surrounding water was directly proportional to photosynthetic production of oxygen in the shoot compartment (Pa). Lr for plants with medium (20-35-cm) stem lengths ranged from less than zero to 0.28 mg O2 (g dry plant)-1 h-1. The fraction of Pa released from roots was inversely proportional to overall stem length, with Lr approaching 18\\% of Pa for short plants (10-15 cm). Mass-specific respiration rates of shorter, more actively growing plants were also 1.5-2.5 times greater than those for longer plants (50-55 cm). In addition, relative Lr (\\% Pa) was inversely related to mass/length, possibly reflecting a higher fraction of stem cross-section as gas space in plants with low mass/length. For natural populations of P. perfoliatus in Chesapeake Bay, Lr was calculated to be 17-22 mg O2 m-2 h-1, representing a relatively small fraction of Pa (3-7\\%). Potential effects of Lr on bacterial metabolism in sediments were also estimated. For example, oxygen release from roots would be sufficient to support 4-6 times ambient nitrification rates or to oxidize all of the sulfide produced from sulfate reduction in unvegetated sediments. © 1986.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Kemp, W. Michael and Murray, Laura},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Rates of photosynthetic production, respiratory consumption and root release of dissolved oxygen (O2) were measured for Potamogeton perfoliatus L. from an estuarine population. Incubations were conducted in split-compartment chambers, with shoots (leaves and stems) separated from roots (plus rhizomes). Time-course observations of O2 exchanges between plants and filtered estuarine water were made at ambient temperatures in natural daylight and in darkness. Release of oxygen from roots (Lr) to surrounding water was directly proportional to photosynthetic production of oxygen in the shoot compartment (Pa). Lr for plants with medium (20-35-cm) stem lengths ranged from less than zero to 0.28 mg O2 (g dry plant)-1 h-1. The fraction of Pa released from roots was inversely proportional to overall stem length, with Lr approaching 18% of Pa for short plants (10-15 cm). Mass-specific respiration rates of shorter, more actively growing plants were also 1.5-2.5 times greater than those for longer plants (50-55 cm). In addition, relative Lr (% Pa) was inversely related to mass/length, possibly reflecting a higher fraction of stem cross-section as gas space in plants with low mass/length. For natural populations of P. perfoliatus in Chesapeake Bay, Lr was calculated to be 17-22 mg O2 m-2 h-1, representing a relatively small fraction of Pa (3-7%). Potential effects of Lr on bacterial metabolism in sediments were also estimated. For example, oxygen release from roots would be sufficient to support 4-6 times ambient nitrification rates or to oxidize all of the sulfide produced from sulfate reduction in unvegetated sediments. © 1986.\n
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\n \n\n \n \n \n \n \n Comparison of methods for measuring production by the submersed macrophyte, Potamogeton perfoliatus L.,.\n \n \n \n\n\n \n Kemp, W. M.; Lewis, M. R.; and Jones, T. W.\n\n\n \n\n\n\n Limnology and Oceanography. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{kemp_comparison_1986,\n\ttitle = {Comparison of methods for measuring production by the submersed macrophyte, {Potamogeton} perfoliatus {L}.,},\n\tdoi = {10.4319/lo.1986.31.6.1322},\n\tabstract = {This article is in Free Access Publication and may be downloaded using the “Download Full Text PDF” link at right. © 1986, by the Association for the Sciences of Limnology and Oceanography, Inc.},\n\tjournal = {Limnology and Oceanography},\n\tauthor = {Kemp, W. Michael and Lewis, Marlon R. and Jones, Thomas W.},\n\tyear = {1986},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n This article is in Free Access Publication and may be downloaded using the “Download Full Text PDF” link at right. © 1986, by the Association for the Sciences of Limnology and Oceanography, Inc.\n
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\n \n\n \n \n \n \n \n Effects of atrazine and linuron on photosynthesis and growth of the macrophytes, Potamogeton perfoliatus L. and Myriophyllum spicatum L. in an estuarine environment.\n \n \n \n\n\n \n Kemp, W. M.; Boynton, W. R.; Cunningham, J. J.; Stevenson, J. C.; Jones, T. W.; and Means, J. C.\n\n\n \n\n\n\n Marine Environmental Research. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{kemp_effects_1985,\n\ttitle = {Effects of atrazine and linuron on photosynthesis and growth of the macrophytes, {Potamogeton} perfoliatus {L}. and {Myriophyllum} spicatum {L}. in an estuarine environment},\n\tdoi = {10.1016/0141-1136(85)90023-6},\n\tabstract = {Phytotoxicities of the herbicides, atrazine and linuron, were evaluated for two species of submersed vascular plants (Potamogeton perfoliatus, L. Myriophyllum spicatum, L.) which, until the late 1960s, had been abundant in Chesapeake Bay. Plants were grown in 50-liter laboratory microcosms, containing filtered estuarine water and sediments for a period of 5 weeks and then treated with atrazine or linuron at initial concentrations of 0, 5, 50, 100, 500 and 1000 gmg/liter. Plant responses were measured primarily in terms of apparent O2 production, P3, and above-ground biomass for 4 weeks post treatment. In general, at ≥ 50 gmg/liter there was a significant depression in Pa for both species and herbicides. However, M. spicatum appeared to be less sensitive, with a significant enhancement in Pa of this species at 5 gmg/liter, and linuron was slightly more effective than atrazine at reducing Pa for both species. Treatment effects on biomass generally paralleled those for Pa. In spite of relatively constant atrazine concentrations (84-89 \\% remaining at termination), both species exhibited evidence of photosynthetic recovery 2-3 weeks after treatment at concentrations ≤ 100 gmg/liter. Using an exponential dose-response model, I50 (concentration for 50 \\% photosynthetic inhibition), ranged from 45-117 gmg/liter for all experiments. In general, in situ concentrations of atrazine and linuron in Chesapeake Bay and its tributaries appear to be sufficient to result in small reductions in Pa (2-10\\%, estimated from dose-response model) during a typical growing season. While such effects may be important for the survival of otherwise stressed plant populations, they suggest that these herbicides, per se, were not the cause of the general decline in abundance of these plants. © 1985.},\n\tjournal = {Marine Environmental Research},\n\tauthor = {Kemp, W. M. and Boynton, W. R. and Cunningham, J. J. and Stevenson, J. C. and Jones, T. W. and Means, J. C.},\n\tyear = {1985},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Phytotoxicities of the herbicides, atrazine and linuron, were evaluated for two species of submersed vascular plants (Potamogeton perfoliatus, L. Myriophyllum spicatum, L.) which, until the late 1960s, had been abundant in Chesapeake Bay. Plants were grown in 50-liter laboratory microcosms, containing filtered estuarine water and sediments for a period of 5 weeks and then treated with atrazine or linuron at initial concentrations of 0, 5, 50, 100, 500 and 1000 gmg/liter. Plant responses were measured primarily in terms of apparent O2 production, P3, and above-ground biomass for 4 weeks post treatment. In general, at ≥ 50 gmg/liter there was a significant depression in Pa for both species and herbicides. However, M. spicatum appeared to be less sensitive, with a significant enhancement in Pa of this species at 5 gmg/liter, and linuron was slightly more effective than atrazine at reducing Pa for both species. Treatment effects on biomass generally paralleled those for Pa. In spite of relatively constant atrazine concentrations (84-89 % remaining at termination), both species exhibited evidence of photosynthetic recovery 2-3 weeks after treatment at concentrations ≤ 100 gmg/liter. Using an exponential dose-response model, I50 (concentration for 50 % photosynthetic inhibition), ranged from 45-117 gmg/liter for all experiments. In general, in situ concentrations of atrazine and linuron in Chesapeake Bay and its tributaries appear to be sufficient to result in small reductions in Pa (2-10%, estimated from dose-response model) during a typical growing season. While such effects may be important for the survival of otherwise stressed plant populations, they suggest that these herbicides, per se, were not the cause of the general decline in abundance of these plants. © 1985.\n
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\n \n\n \n \n \n \n \n The effects of grazers and light penetration on the survival of transplants of Vallisneria americana Michs in the tidal Potomac River, Maryland.\n \n \n \n\n\n \n Carter, V.; and Rybicki, N. B.\n\n\n \n\n\n\n Aquatic Botany. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{carter_effects_1985,\n\ttitle = {The effects of grazers and light penetration on the survival of transplants of {Vallisneria} americana {Michs} in the tidal {Potomac} {River}, {Maryland}},\n\tdoi = {10.1016/0304-3770(85)90066-X},\n\tabstract = {Poor light penetration and grazing are among the factors potentially responsible for the lack of submersed aquatic macrophytes in the tidal Potomac River. Between 1980 and 1983, plugs, springs and tubers of Vallisneria americana Michx were transplanted from the oligohaline Potomac Estuary to six sites in the freshwater tidal Potomac River. Transplants made in 1980 and 1981 were generally successful only when protected by full exclosures which prevented grazing. Grazing resulted in the removal of whole plants or clipping off of plant leaves in unprotected plots. Plants protected in the first year were permanently established, despite the occurrence of grazing in subsequent years, at Elodea Cove and Rosier Bluff, where light penetration was high (average 1\\% light level was 1.6-1.7 m). Plants were not permanent;y established at Goose Island, where light penetration was lower (average 1\\% light level was 1.4 m) and grazing occurred, or Neabsco Bay where light penetration was very low (average 1\\% light level was 1.0 m) and grazing may not have occurred. In 1983, Secchi depth transparencies in the upper tidal river were improved significantly compared to 1978-1981. Both protected and unprotected transplants thrived in 1983. © 1985.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B.},\n\tyear = {1985},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Poor light penetration and grazing are among the factors potentially responsible for the lack of submersed aquatic macrophytes in the tidal Potomac River. Between 1980 and 1983, plugs, springs and tubers of Vallisneria americana Michx were transplanted from the oligohaline Potomac Estuary to six sites in the freshwater tidal Potomac River. Transplants made in 1980 and 1981 were generally successful only when protected by full exclosures which prevented grazing. Grazing resulted in the removal of whole plants or clipping off of plant leaves in unprotected plots. Plants protected in the first year were permanently established, despite the occurrence of grazing in subsequent years, at Elodea Cove and Rosier Bluff, where light penetration was high (average 1% light level was 1.6-1.7 m). Plants were not permanent;y established at Goose Island, where light penetration was lower (average 1% light level was 1.4 m) and grazing occurred, or Neabsco Bay where light penetration was very low (average 1% light level was 1.0 m) and grazing may not have occurred. In 1983, Secchi depth transparencies in the upper tidal river were improved significantly compared to 1978-1981. Both protected and unprotected transplants thrived in 1983. © 1985.\n
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\n \n\n \n \n \n \n \n Nutrient enrichment of estuarine submersed vascular plant communities. 1. Algal growth and effects on production of plants and associated communities.\n \n \n \n\n\n \n Twilley, R.; Kemp, W.; Staver, K.; Stevenson, J.; and Boynton, W.\n\n\n \n\n\n\n Marine Ecology Progress Series. 1985.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{twilley_nutrient_1985,\n\ttitle = {Nutrient enrichment of estuarine submersed vascular plant communities. 1. {Algal} growth and effects on production of plants and associated communities},\n\tdoi = {10.3354/meps023179},\n\tabstract = {ABSTRACT: Eight experimental ponds containing submersed vascular plants (predominantly Potamogeton perfoliatus and Ruppja maritirna) were subjected in duplicate to 4 levels (including controls) of fertilization from June to August 1981. Seston and phytoplankton chlorophyll a increased with fertilization, and pronounced algal blooms were evident under high dosage. Of the total seston. phytoplankton exerted the greatest influence on attenuation of photosynthetically active radiation (PAR), such that there was insufficient light for submersed vascular plant growth at the sediment surface during bloonls. An extensive epiphytic community developed on plants in all nutrient-treated ponds at densities similar to those observed in nature on senescent plants. At high nutrient treatments the accumulation of epiphytic material resulted in {\\textbackslash}textgreater 80 \\% attenuation of the incident radiation at the leaf surface. Biomass of submersed macrophytes decreased significantly under high and medium nutrient treatments compared to control and low treatments within 60 d following initial fertilization. Apparent production of vascular plants (based on oxygen production and I4C-bicarbonate uptake) was reduced at the higher nutrient treatments for both R. maritirna and P. perfoliatus. Most of this reduction in macrophyte photosynthesis could be explained by attenuation of PAR associated with epiphytic material. However, without PAR attenuance in the overlying water, observed levels of epiphytic growth would be insufficient to reduce light below compensation levels needed to sustain vascular plant growth. At the high fertilization rates, integrated primary production of pond communities was significantly reduced with the loss of the vascular plants, even though phytoplankton and epiphytic growth},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Twilley, RR and Kemp, WM and Staver, KW and Stevenson, JC and Boynton, WR},\n\tyear = {1985},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n ABSTRACT: Eight experimental ponds containing submersed vascular plants (predominantly Potamogeton perfoliatus and Ruppja maritirna) were subjected in duplicate to 4 levels (including controls) of fertilization from June to August 1981. Seston and phytoplankton chlorophyll a increased with fertilization, and pronounced algal blooms were evident under high dosage. Of the total seston. phytoplankton exerted the greatest influence on attenuation of photosynthetically active radiation (PAR), such that there was insufficient light for submersed vascular plant growth at the sediment surface during bloonls. An extensive epiphytic community developed on plants in all nutrient-treated ponds at densities similar to those observed in nature on senescent plants. At high nutrient treatments the accumulation of epiphytic material resulted in \\textgreater 80 % attenuation of the incident radiation at the leaf surface. Biomass of submersed macrophytes decreased significantly under high and medium nutrient treatments compared to control and low treatments within 60 d following initial fertilization. Apparent production of vascular plants (based on oxygen production and I4C-bicarbonate uptake) was reduced at the higher nutrient treatments for both R. maritirna and P. perfoliatus. Most of this reduction in macrophyte photosynthesis could be explained by attenuation of PAR associated with epiphytic material. However, without PAR attenuance in the overlying water, observed levels of epiphytic growth would be insufficient to reduce light below compensation levels needed to sustain vascular plant growth. At the high fertilization rates, integrated primary production of pond communities was significantly reduced with the loss of the vascular plants, even though phytoplankton and epiphytic growth\n
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\n \n\n \n \n \n \n \n A water-quality study of the tidal Potomac River and Estuary - an overview.\n \n \n \n\n\n \n Callender, E.; Carter, V.; Hahl, D. C.; Hitt, K.; and Schultz, B. I.\n\n\n \n\n\n\n US Geological Survey Water-Supply Paper. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{callender_water-quality_1984,\n\ttitle = {A water-quality study of the tidal {Potomac} {River} and {Estuary} - an overview.},\n\tabstract = {The objectives of the study are: to provide a basic understanding of physical, chemical, and biological processes; to develop flow and transport models to predict the movement and fate of nutrients and algae; and to develop efficient techniques for the study of tidal rivers and estuaries. The ultimate goal is to aid water-quality decisionmaking for the tidal Potomac River and Estuary.-from Authors},\n\tjournal = {US Geological Survey Water-Supply Paper},\n\tauthor = {Callender, E. and Carter, V. and Hahl, D. C. and Hitt, K. and Schultz, B. I.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The objectives of the study are: to provide a basic understanding of physical, chemical, and biological processes; to develop flow and transport models to predict the movement and fate of nutrients and algae; and to develop efficient techniques for the study of tidal rivers and estuaries. The ultimate goal is to aid water-quality decisionmaking for the tidal Potomac River and Estuary.-from Authors\n
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\n \n\n \n \n \n \n \n Uptake and Photosynthetic Inhibition by Atrazine and its Degradation Products on Four Species of Submerged Vascular Plants.\n \n \n \n\n\n \n Jones, T. W.; and Winchell, L.\n\n\n \n\n\n\n Journal of Environmental Quality. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{jones_uptake_1984-1,\n\ttitle = {Uptake and {Photosynthetic} {Inhibition} by {Atrazine} and its {Degradation} {Products} on {Four} {Species} of {Submerged} {Vascular} {Plants}},\n\tdoi = {10.2134/jeq1984.00472425001300020014x},\n\tabstract = {The photosynthetic inhibitory effect of atrazine [1912-24-9] and 3 of its major metabolites (deethylatrazine [6190-65-4], deisopropylatrazine [1007-28-9], and hydroxyatrazine [2163-68-0]) were detd. for Potamogeton perfoliatus, Ruppia maritima, Myriophyllum spicatum and Zannichellia palustris. The 4 species showed a similar response to varied dosages of the parent atrazine with an av. I1 (concn. at which photosynthesis is inhibited by 1\\%) for the 4 species of 20 micro g/L and an av. I50 (concn. at which photosynthesis is inhibited by 50\\%) for the 4 species of 95 micro g/L. The 3 major degrdn. metabolites of atrazine produced varying degrees of photosynthetic inhibition in the 4 species, but generally the order of toxicity was: deethylated {\\textbackslash}textgreater deisopropylated {\\textbackslash}textgreater hydroxyatrazine, with hydroxyatrazine causing an apparent stimulation of photosynthesis in several species. Of 4 species tested, M. spicatum was the most resistant to atrazine and its metabolites. The magnitude of the actual uptake of the compds. (micro g compd./g dry wt plant) correlated closely with the photosynthetic inhibitory response, i.e. atrazine {\\textbackslash}textgreater deethylated {\\textbackslash}textgreater deisopropylated {\\textbackslash}textgreater hydroxyatrazine. Considering that an extremely high environmental concn. (0.5 mg/L) of deethylated atrazine in an estuary produced only a photosynthetic inhibition of 20-40\\% in 4 major species of submerged macrophytes, it is concluded that the degrdn. products of atrazine did not play a major role in the disappearance of the submerged vascular plants from the Chesapeake Bay.},\n\tjournal = {Journal of Environmental Quality},\n\tauthor = {Jones, T. W. and Winchell, L.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The photosynthetic inhibitory effect of atrazine [1912-24-9] and 3 of its major metabolites (deethylatrazine [6190-65-4], deisopropylatrazine [1007-28-9], and hydroxyatrazine [2163-68-0]) were detd. for Potamogeton perfoliatus, Ruppia maritima, Myriophyllum spicatum and Zannichellia palustris. The 4 species showed a similar response to varied dosages of the parent atrazine with an av. I1 (concn. at which photosynthesis is inhibited by 1%) for the 4 species of 20 micro g/L and an av. I50 (concn. at which photosynthesis is inhibited by 50%) for the 4 species of 95 micro g/L. The 3 major degrdn. metabolites of atrazine produced varying degrees of photosynthetic inhibition in the 4 species, but generally the order of toxicity was: deethylated \\textgreater deisopropylated \\textgreater hydroxyatrazine, with hydroxyatrazine causing an apparent stimulation of photosynthesis in several species. Of 4 species tested, M. spicatum was the most resistant to atrazine and its metabolites. The magnitude of the actual uptake of the compds. (micro g compd./g dry wt plant) correlated closely with the photosynthetic inhibitory response, i.e. atrazine \\textgreater deethylated \\textgreater deisopropylated \\textgreater hydroxyatrazine. Considering that an extremely high environmental concn. (0.5 mg/L) of deethylated atrazine in an estuary produced only a photosynthetic inhibition of 20-40% in 4 major species of submerged macrophytes, it is concluded that the degrdn. products of atrazine did not play a major role in the disappearance of the submerged vascular plants from the Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n Uptake and phytotoxicity of soil-sorbed atrazine for the submerged aquatic plant, Potamogeton perfoliatus L.\n \n \n \n\n\n \n Jones, T. W.; and Estes, P. S.\n\n\n \n\n\n\n Archives of Environmental Contamination and Toxicology. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{jones_uptake_1984,\n\ttitle = {Uptake and phytotoxicity of soil-sorbed atrazine for the submerged aquatic plant, {Potamogeton} perfoliatus {L}.},\n\tdoi = {10.1007/BF01055882},\n\tabstract = {The photosynthetic inhibitory effect of atrazine-sorbed soil placed on the leaf surfaces of Potamogeton perfoliatus was investigated under laboratory conditions. Leaves simultaneously exposed to atrazine both in solution and sorbed to soil exhibited a similar uptake of atrazine and associated photosynthetic reduction as did leaves exposed to the same concentration of atrazine in solution only. A small quantity of atrazine (0.19 μ/gdw leaf) was found in leaves treated with atrazine-sorbed soil at 120 μ/kg whereas a significantly larger amount (3.57 μg/gdw leaf) was present in leaves treated with dissolved atrazine at a concentration of 100 μg/L. It is concluded that atrazine sorbed to soil on leaf surfaces is less available for uptake by aquatic plants than atrazine in solution. Of greater physiological concern is the physical presence of the soil on the leaves and the resultant reduction of light. © 1984 Springer-Verlag New York Inc.},\n\tjournal = {Archives of Environmental Contamination and Toxicology},\n\tauthor = {Jones, T. W. and Estes, P. S.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The photosynthetic inhibitory effect of atrazine-sorbed soil placed on the leaf surfaces of Potamogeton perfoliatus was investigated under laboratory conditions. Leaves simultaneously exposed to atrazine both in solution and sorbed to soil exhibited a similar uptake of atrazine and associated photosynthetic reduction as did leaves exposed to the same concentration of atrazine in solution only. A small quantity of atrazine (0.19 μ/gdw leaf) was found in leaves treated with atrazine-sorbed soil at 120 μ/kg whereas a significantly larger amount (3.57 μg/gdw leaf) was present in leaves treated with dissolved atrazine at a concentration of 100 μg/L. It is concluded that atrazine sorbed to soil on leaf surfaces is less available for uptake by aquatic plants than atrazine in solution. Of greater physiological concern is the physical presence of the soil on the leaves and the resultant reduction of light. © 1984 Springer-Verlag New York Inc.\n
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\n \n\n \n \n \n \n \n Temporal responses of the macrophyte, Potamogeton perfoliatus L., and its associated autotrophic community to atrazine exposure in estuarine microcosms.\n \n \n \n\n\n \n Cunningham, J. J.; Kemp, W. M.; Lewis, M. R.; and Stevenson, J. C.\n\n\n \n\n\n\n Estuaries. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{cunningham_temporal_1984,\n\ttitle = {Temporal responses of the macrophyte, {Potamogeton} perfoliatus {L}., and its associated autotrophic community to atrazine exposure in estuarine microcosms},\n\tdoi = {10.2307/1352057},\n\tabstract = {Effects of the herbicide, atrazine, on the submersed vascular plant, Potamogeton perfoliatus, were monitored for 4 wk in 700 l microcosms containing water, sediments and plants from upper Chesapeake Bay. Two atrazine treatments (plus controls) were employed in duplicate systems, with water column concentrations averaging about 0.13 and 1.20 μg per 1, respectively. Atrazine concentrations at low dose were in the range of the highest values reported in Chesapeake Bay, and significant decreases in apparent O 2 production (P a ) of P. perfoliatus were observed immediately following treatment. However, significant recovery of P a was evident at low dose within 2 wk, even though atrazine levels remained relatively constant. At the higher atrazine treatment, phytotoxic effects were even more pronounced, with no recovery occurring during the study period. Integrated community production and consumption of O 2 followed patterns similar to those for P. perfoliatus alone, with some minor increases in relative contributions of other autotrophic groups (phytoplankton, epiphytes, benthic microalgae). While areal densities of plant shoots for the experimental populations were unaffected by the lower treatment, total biomass decreased significantly, lagging 2-4 wk after the initial decrease in P a . Morphology of individual shoots was markedly influenced by atrazine, with significant increases in mean shoot length and decreases in weight per unit length. Furthermore, chlorophyll a content of leaves increased 5-fold with atrazine treatment. These effects are similar to previously reported shade adaptations of this and other submersed plants. © 1984 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {Cunningham, J. J. and Kemp, W. M. and Lewis, M. R. and Stevenson, J. C.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Effects of the herbicide, atrazine, on the submersed vascular plant, Potamogeton perfoliatus, were monitored for 4 wk in 700 l microcosms containing water, sediments and plants from upper Chesapeake Bay. Two atrazine treatments (plus controls) were employed in duplicate systems, with water column concentrations averaging about 0.13 and 1.20 μg per 1, respectively. Atrazine concentrations at low dose were in the range of the highest values reported in Chesapeake Bay, and significant decreases in apparent O 2 production (P a ) of P. perfoliatus were observed immediately following treatment. However, significant recovery of P a was evident at low dose within 2 wk, even though atrazine levels remained relatively constant. At the higher atrazine treatment, phytotoxic effects were even more pronounced, with no recovery occurring during the study period. Integrated community production and consumption of O 2 followed patterns similar to those for P. perfoliatus alone, with some minor increases in relative contributions of other autotrophic groups (phytoplankton, epiphytes, benthic microalgae). While areal densities of plant shoots for the experimental populations were unaffected by the lower treatment, total biomass decreased significantly, lagging 2-4 wk after the initial decrease in P a . Morphology of individual shoots was markedly influenced by atrazine, with significant increases in mean shoot length and decreases in weight per unit length. Furthermore, chlorophyll a content of leaves increased 5-fold with atrazine treatment. These effects are similar to previously reported shade adaptations of this and other submersed plants. © 1984 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n INFLUENCES OF SUBMERSED VASCULAR PLANTS ON ECOLOGICAL PROCESSES IN UPPER CHESAPEAKE BAY.\n \n \n \n\n\n \n Kemp, W. M.; Boynton, W. R.; Twilley, R. R.; Stevenson, J. C.; and Ward, L. G.\n\n\n \n\n\n\n In The Estuary As a Filter. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@incollection{kemp_influences_1984,\n\ttitle = {{INFLUENCES} {OF} {SUBMERSED} {VASCULAR} {PLANTS} {ON} {ECOLOGICAL} {PROCESSES} {IN} {UPPER} {CHESAPEAKE} {BAY}},\n\tabstract = {() In: (ed) . , p},\n\tbooktitle = {The {Estuary} {As} a {Filter}},\n\tauthor = {Kemp, W. Michael and Boynton, Walter R. and Twilley, Robert R. and Stevenson, J. Court and Ward, Larry G.},\n\tyear = {1984},\n\tdoi = {10.1016/b978-0-12-405070-9.50023-2},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n () In: (ed) . , p\n
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\n \n\n \n \n \n \n \n Effects of the herbicide atrazine on adenine nucleotide levels in Zostera marina L. (eelgrass).\n \n \n \n\n\n \n Delistraty, D. A.; and Hershner, C.\n\n\n \n\n\n\n Aquatic Botany. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{delistraty_effects_1984,\n\ttitle = {Effects of the herbicide atrazine on adenine nucleotide levels in {Zostera} marina {L}. (eelgrass)},\n\tdoi = {10.1016/0304-3770(84)90056-1},\n\tabstract = {Response of adenine nucleotides (ATP, ADP, AMP) and adenylate energy charge (EC) to atrazine, a triazine herbicide, was evaluated as an indicator of metabolic state in Zostera marina L. (eelgrass), a submerged marine angiosperm. Short-term (6 h) atrazine stress reduced ATP and total adenylates (AT) at both 10 and 100 ppb, but EC remained constant. Net productivity decreased at 100, but not at 10 ppb atrazine over 6 h. Long-term (21 day) atrazine stress was evidenced by growth inhibition and 50\\% mortality near 100 ppb. EC was reduced at 0.1, 1.0 and 10 ppb atrazine, but ATP and EC increased with physiological response to severe stress (100 ppb) after 21 days. Apparently, ATP and AT decrease over the short-term but rebound over the long-term with severe atrazine stress, increasing beyond control levels before plant death results. Supplementing adenine nucleotide and EC results with more conventional quantitative analyses should afford greater knowledge of physiological response to environmental variation. © 1984.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Delistraty, D. A. and Hershner, C.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Response of adenine nucleotides (ATP, ADP, AMP) and adenylate energy charge (EC) to atrazine, a triazine herbicide, was evaluated as an indicator of metabolic state in Zostera marina L. (eelgrass), a submerged marine angiosperm. Short-term (6 h) atrazine stress reduced ATP and total adenylates (AT) at both 10 and 100 ppb, but EC remained constant. Net productivity decreased at 100, but not at 10 ppb atrazine over 6 h. Long-term (21 day) atrazine stress was evidenced by growth inhibition and 50% mortality near 100 ppb. EC was reduced at 0.1, 1.0 and 10 ppb atrazine, but ATP and EC increased with physiological response to severe stress (100 ppb) after 21 days. Apparently, ATP and AT decrease over the short-term but rebound over the long-term with severe atrazine stress, increasing beyond control levels before plant death results. Supplementing adenine nucleotide and EC results with more conventional quantitative analyses should afford greater knowledge of physiological response to environmental variation. © 1984.\n
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\n \n\n \n \n \n \n \n Epiphyte-grazer relationships in seagrass meadows: Consequences for seagrass growth and production.\n \n \n \n\n\n \n van Montfrans, J.; Wetzel, R. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{van_montfrans_epiphyte-grazer_1984,\n\ttitle = {Epiphyte-grazer relationships in seagrass meadows: {Consequences} for seagrass growth and production},\n\tdoi = {10.2307/1351615},\n\tabstract = {Studies of seagrass meadows have shown that the production of algal epiphytes attached to seagrass blades approaches 20\\% of the seagrass production and that epiphytes are more important as food for associated fauna than are the more refractory seagrass blades. Since epiphytes may compete with seagrasses for light and water column nutrients, excessive epiphytic fouling could have serious consequences for seagrass growth. We summarize much of the literature on epiphytegrazer relationships in seagrass meadows within the context of seagrass growth and production. We also provide insights from mathematical modeling simulations of these relationships for a Chesapeake Bay Zostera marina meadow. Finally we focus on future research needs for more completely understanding the influences that epiphyte grazers have on seagrass production. © 1984 Estuarine Research Federation.},\n\tjournal = {Estuaries},\n\tauthor = {van Montfrans, Jacques and Wetzel, Richard L. and Orth, Robert J.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Studies of seagrass meadows have shown that the production of algal epiphytes attached to seagrass blades approaches 20% of the seagrass production and that epiphytes are more important as food for associated fauna than are the more refractory seagrass blades. Since epiphytes may compete with seagrasses for light and water column nutrients, excessive epiphytic fouling could have serious consequences for seagrass growth. We summarize much of the literature on epiphytegrazer relationships in seagrass meadows within the context of seagrass growth and production. We also provide insights from mathematical modeling simulations of these relationships for a Chesapeake Bay Zostera marina meadow. Finally we focus on future research needs for more completely understanding the influences that epiphyte grazers have on seagrass production. © 1984 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n Growth of Zostera marina L. Seedlings under laboratory conditions of nutrient enrichment.\n \n \n \n\n\n \n Roberts, M. H.; Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 1984.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{roberts_growth_1984,\n\ttitle = {Growth of {Zostera} marina {L}. {Seedlings} under laboratory conditions of nutrient enrichment},\n\tdoi = {10.1016/0304-3770(84)90095-0},\n\tabstract = {The effect of increased nutrients on growth of Zostera marina L. seedlings was tested in the laboratory by adding 2 different formulations (18:6:12 and 14:14:14 Nitrogen: Phosphorus:Potassium (N:P:K), respectively) of a slow release fertilizer, Osmocote®. Three different application rates were used with the 2 formulations by placing appropriate amounts in peat pots containing 1 seedling each. The addition of fertilizer to the substrate markedly stimulated the growth of seedlings. Nutrient enrichment promoted growth both in terms of increased leaf length and vegetative production of shoots. The nitrogen rich formulation (18:6:12) produced less growth than the equal balance formulation (14:14:14). For both formulations, the highest concentrations produced greater growth than other concentrations of the same formulation. At equal application rates with respect to nitrogen, less growth occurred in the treatments receiving less phosphorus. Results of this experiment corroborate results from previous work suggesting that addition of nutrients to the sediment can stimulate Z. marina growth. © 1984.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Roberts, Morris H. and Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1984},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The effect of increased nutrients on growth of Zostera marina L. seedlings was tested in the laboratory by adding 2 different formulations (18:6:12 and 14:14:14 Nitrogen: Phosphorus:Potassium (N:P:K), respectively) of a slow release fertilizer, Osmocote®. Three different application rates were used with the 2 formulations by placing appropriate amounts in peat pots containing 1 seedling each. The addition of fertilizer to the substrate markedly stimulated the growth of seedlings. Nutrient enrichment promoted growth both in terms of increased leaf length and vegetative production of shoots. The nitrogen rich formulation (18:6:12) produced less growth than the equal balance formulation (14:14:14). For both formulations, the highest concentrations produced greater growth than other concentrations of the same formulation. At equal application rates with respect to nitrogen, less growth occurred in the treatments receiving less phosphorus. Results of this experiment corroborate results from previous work suggesting that addition of nutrients to the sediment can stimulate Z. marina growth. © 1984.\n
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\n \n\n \n \n \n \n \n PRODUCTION ECOLOGY OF SEAGRASS COMMUNITIES IN THE LOWER CHESAPEAKE BAY.\n \n \n \n\n\n \n Wetzel, R. L.; and Penhale, P. A.\n\n\n \n\n\n\n Marine Technology Society Journal. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{wetzel_production_1983,\n\ttitle = {{PRODUCTION} {ECOLOGY} {OF} {SEAGRASS} {COMMUNITIES} {IN} {THE} {LOWER} {CHESAPEAKE} {BAY}.},\n\tabstract = {The article reports recent findings on structural and functional aspects of the ecology of a seagrass meadow that characterizes lower bay submerged aquatic vascular plant communities dominated by two species; Ruppia maritima L. and Zostera marina L. Submarine light in the photosynthetically active wavelengths and light-temperature interactions are the principal environmental controls.},\n\tjournal = {Marine Technology Society Journal},\n\tauthor = {Wetzel, Richard L. and Penhale, Polly A.},\n\tyear = {1983},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The article reports recent findings on structural and functional aspects of the ecology of a seagrass meadow that characterizes lower bay submerged aquatic vascular plant communities dominated by two species; Ruppia maritima L. and Zostera marina L. Submarine light in the photosynthetically active wavelengths and light-temperature interactions are the principal environmental controls.\n
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\n \n\n \n \n \n \n \n DECLINE OF SUBMERGED VASCULAR PLANTS IN UPPER CHESAPEAKE BAY: SUMMARY OF RESULTS CONCERNING POSSIBLE CAUSES.\n \n \n \n\n\n \n Kemp, M. W.; Twilley, R. R.; Stevenson, J. C.; Boynton, W. R.; and Means, J. C.\n\n\n \n\n\n\n Marine Technology Society Journal. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{kemp_decline_1983,\n\ttitle = {{DECLINE} {OF} {SUBMERGED} {VASCULAR} {PLANTS} {IN} {UPPER} {CHESAPEAKE} {BAY}: {SUMMARY} {OF} {RESULTS} {CONCERNING} {POSSIBLE} {CAUSES}.},\n\tabstract = {This paper provides a summary of research conducted to investigate possible causes of the decline in abundance of submerged aquatic vegetation beginning in the late 1960s. Three factors are emphasized: runoff of agricultural herbicides; erosional inputs of fine-grain sediments; nutrient enrichment and associated algal growth. The results are synthesized into an ecosystem simulation model which demonstrated relative potential contributions, where nutrients greater than sediments greater than herbicides. Other factors and mechanisms are also discussed along with resource managements options.},\n\tjournal = {Marine Technology Society Journal},\n\tauthor = {Kemp, Michael W. and Twilley, Robert R. and Stevenson, J. Court and Boynton, Walter R. and Means, Jay C.},\n\tyear = {1983},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n This paper provides a summary of research conducted to investigate possible causes of the decline in abundance of submerged aquatic vegetation beginning in the late 1960s. Three factors are emphasized: runoff of agricultural herbicides; erosional inputs of fine-grain sediments; nutrient enrichment and associated algal growth. The results are synthesized into an ecosystem simulation model which demonstrated relative potential contributions, where nutrients greater than sediments greater than herbicides. Other factors and mechanisms are also discussed along with resource managements options.\n
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\n \n\n \n \n \n \n \n A rapid technique for preparation of aquatic macrophyte samples for measuring 14C incorporation.\n \n \n \n\n\n \n Lewis, M. R.; Kemp, W. M.; Cunningham, J. J.; and Court Stevenson, J.\n\n\n \n\n\n\n Aquatic Botany. 1982.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{lewis_rapid_1982,\n\ttitle = {A rapid technique for preparation of aquatic macrophyte samples for measuring {14C} incorporation},\n\tdoi = {10.1016/0304-3770(82)90054-7},\n\tabstract = {A nitric acid digestion method is presented for rapid and inexpensive preparation of 14C-labelled macrophyte tissue for liquid scintillation counting. No significant difference was found when the method was compared to combustion in oxygen. Results from time-series experiments with labelled sucrose as well as plant materials indicated little loss of labelled organics as volatile compounds over a 16 h period, and complete recovery of the label was attained. © 1982.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Lewis, Marlon R. and Kemp, W. Michael and Cunningham, Jeffrey J. and Court Stevenson, J.},\n\tyear = {1982},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n A nitric acid digestion method is presented for rapid and inexpensive preparation of 14C-labelled macrophyte tissue for liquid scintillation counting. No significant difference was found when the method was compared to combustion in oxygen. Results from time-series experiments with labelled sucrose as well as plant materials indicated little loss of labelled organics as volatile compounds over a 16 h period, and complete recovery of the label was attained. © 1982.\n
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\n \n\n \n \n \n \n \n Atrazine toxicity to submersed vascular plants in simulated estuarine microcosms.\n \n \n \n\n\n \n Correll, D. L.; and Wu, T. L.\n\n\n \n\n\n\n Aquatic Botany. 1982.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{correll_atrazine_1982,\n\ttitle = {Atrazine toxicity to submersed vascular plants in simulated estuarine microcosms},\n\tdoi = {10.1016/0304-3770(82)90094-8},\n\tabstract = {Photosynthesis in Potamogeton pectinatus L. and Zostera marina L. was inhibited by 650 μg 1-1 of dissolved atrazine, but was stimulated by 75 μg 1-1. Photosynthesis in Zannichellia palustris L. was inhibited at both of these concentrations while in Vallisneria americana Michx inhibition was significant at the higher concentration but minor at the lower concentration. Atrazine at 120 μg 1-1 in solution caused 100\\% mortality of Vallisneria within 30 days. At 12 μg 1-1 mortality of Vallisneria was 50\\% after 47 days and the production of new plants at the ends of runners and leaf area increase of survivors were significantly reduced. Treatment with 3.2 μg 1-1 had relatively minor effects and results from exposure to 1.3 μg 1-1 were indistinguishable from controls. Data were also taken on the partitioning of atrazine between the abiotic phases in the microcosms and on rate of atrazine breakdown. © 1982.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Correll, David L. and Wu, Tung L.},\n\tyear = {1982},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n Photosynthesis in Potamogeton pectinatus L. and Zostera marina L. was inhibited by 650 μg 1-1 of dissolved atrazine, but was stimulated by 75 μg 1-1. Photosynthesis in Zannichellia palustris L. was inhibited at both of these concentrations while in Vallisneria americana Michx inhibition was significant at the higher concentration but minor at the lower concentration. Atrazine at 120 μg 1-1 in solution caused 100% mortality of Vallisneria within 30 days. At 12 μg 1-1 mortality of Vallisneria was 50% after 47 days and the production of new plants at the ends of runners and leaf area increase of survivors were significantly reduced. Treatment with 3.2 μg 1-1 had relatively minor effects and results from exposure to 1.3 μg 1-1 were indistinguishable from controls. Data were also taken on the partitioning of atrazine between the abiotic phases in the microcosms and on rate of atrazine breakdown. © 1982.\n
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\n \n\n \n \n \n \n \n NITROGEN CYCLING AND ESTUARINE INTERFACES: SOME CURRENT CONCEPTS AND RESEARCH DIRECTIONS.\n \n \n \n\n\n \n Kemp, W. M.; Wetzel, R. L.; Boynton, W. R.; D'Elia, C. F.; and Stevenson, J. C.\n\n\n \n\n\n\n In Estuarine Comparisons. 1982.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@incollection{kemp_nitrogen_1982,\n\ttitle = {{NITROGEN} {CYCLING} {AND} {ESTUARINE} {INTERFACES}: {SOME} {CURRENT} {CONCEPTS} {AND} {RESEARCH} {DIRECTIONS}},\n\tabstract = {The role of physical interfaces in estuarine nitrogen (N) dynamics is discussed. We consider here: four N-transformation processes (uptake, regeneration, de nitrification, nitrification) and five interfaces (water mass fronts and transitions, watershed-estuarine boundaries, the pycnocline of stratified estuaries, the sediment-water boundary, the redox discontinuity layer). Seven examples are presented. First, we show that phytoplankton production and, in turn, NH+4 recycling can be stimulated at interfaces where two water masses meet, with one being relatively clear and the other nutrient-rich. Second, data are provided to illustrate that N recycling rates tend to exceed (by 2–8 fold) inputs of “new” N entering across watershed-estuary boundaries, although annual net primary production is more a function of the latter. Third, we argue that periodic occurrences of high NH+4 concentrations in strongly stratified water columns reflect active NH+4 oxidation at the estuarine pynocline. Fourth, evidence is given to indicate that intensive remineralization of NH+4 occurs in the uppermost flocculent layer of sediments, and that fluxes estimated from diagenic modeling would tend to overlook this. Next, we show that denitrification, which is concentrated near the sediment redox discontinuity layer (RDL), may be a major component of estuarine N budgets (50–60\\% of NH+4 recycling). Sixth, we indicate that de nitrification can be fueled either by sediment nitrification just above the RDL or via NO−3 diffusion from overlying waters. Seventh, recent experimental results are considered to demonstrate the effects of macrophytic roots enhancing nitrification (and possibly denitrification) by transporting O2 and deepening the oxidized zone of sediments. Finally, we propose some generic properties of estuarine interfaces which may account for their importance in N cycling.},\n\tbooktitle = {Estuarine {Comparisons}},\n\tauthor = {Kemp, W. Michael and Wetzel, Richard L. and Boynton, Walter R. and D'Elia, Christopher F. and Stevenson, J. Court},\n\tyear = {1982},\n\tdoi = {10.1016/b978-0-12-404070-0.50018-1},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The role of physical interfaces in estuarine nitrogen (N) dynamics is discussed. We consider here: four N-transformation processes (uptake, regeneration, de nitrification, nitrification) and five interfaces (water mass fronts and transitions, watershed-estuarine boundaries, the pycnocline of stratified estuaries, the sediment-water boundary, the redox discontinuity layer). Seven examples are presented. First, we show that phytoplankton production and, in turn, NH+4 recycling can be stimulated at interfaces where two water masses meet, with one being relatively clear and the other nutrient-rich. Second, data are provided to illustrate that N recycling rates tend to exceed (by 2–8 fold) inputs of “new” N entering across watershed-estuary boundaries, although annual net primary production is more a function of the latter. Third, we argue that periodic occurrences of high NH+4 concentrations in strongly stratified water columns reflect active NH+4 oxidation at the estuarine pynocline. Fourth, evidence is given to indicate that intensive remineralization of NH+4 occurs in the uppermost flocculent layer of sediments, and that fluxes estimated from diagenic modeling would tend to overlook this. Next, we show that denitrification, which is concentrated near the sediment redox discontinuity layer (RDL), may be a major component of estuarine N budgets (50–60% of NH+4 recycling). Sixth, we indicate that de nitrification can be fueled either by sediment nitrification just above the RDL or via NO−3 diffusion from overlying waters. Seventh, recent experimental results are considered to demonstrate the effects of macrophytic roots enhancing nitrification (and possibly denitrification) by transporting O2 and deepening the oxidized zone of sediments. Finally, we propose some generic properties of estuarine interfaces which may account for their importance in N cycling.\n
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\n \n\n \n \n \n \n \n Micricosms, Macrophytes, and Hierarchies: Environmental Research in the Chesapeake Bay.\n \n \n \n\n\n \n Kemp, W M; Lewis, M R; Cunningham, J J; Stevenson, J C; and Boynton, W R\n\n\n \n\n\n\n Microcosms in Ecological Research. 1980.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{kemp_micricosms_1980,\n\ttitle = {Micricosms, {Macrophytes}, and {Hierarchies}: {Environmental} {Research} in the {Chesapeake} {Bay}},\n\tabstract = {A format for the design of large environmental studies is presented which focuses research on a hierarchy of different scales ranging from microcosms to field experiments. This design is illustrated using as an example a current study of submerged macrophytes in the Chesapeake Bay. It is suggested that three funcamental criteria (controllability, realism, and generality) should be considered in such research designs; controllability decreases with scale of study in the hierarchical scheme, and realism and generality increase with scale. Generality may be extended at each scale by building mathematically abstract models and by performing multiple experiments. Results of studies of large (700 liter) laboratory microcosms are presented to demonstrate the utility of such experimental systems for examining effects of herbicide stress on estuarine macrophyte communities, where community, macrophyte, and phytoplankton photosynthesis (P), respiration (R), and photosynthesis-respiration ratios exhibited clear patterns of response to perturbations.},\n\tjournal = {Microcosms in Ecological Research},\n\tauthor = {Kemp, W M and Lewis, M R and Cunningham, J J and Stevenson, J C and Boynton, W R},\n\tyear = {1980},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n A format for the design of large environmental studies is presented which focuses research on a hierarchy of different scales ranging from microcosms to field experiments. This design is illustrated using as an example a current study of submerged macrophytes in the Chesapeake Bay. It is suggested that three funcamental criteria (controllability, realism, and generality) should be considered in such research designs; controllability decreases with scale of study in the hierarchical scheme, and realism and generality increase with scale. Generality may be extended at each scale by building mathematically abstract models and by performing multiple experiments. Results of studies of large (700 liter) laboratory microcosms are presented to demonstrate the utility of such experimental systems for examining effects of herbicide stress on estuarine macrophyte communities, where community, macrophyte, and phytoplankton photosynthesis (P), respiration (R), and photosynthesis-respiration ratios exhibited clear patterns of response to perturbations.\n
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\n \n\n \n \n \n \n \n Nitrogen fixation associated with four species of submerged angiosperms in the central Chesapeake bay.\n \n \n \n\n\n \n Lipschultz, F.; Cunningham, J. J.; and Court Stevenson, J.\n\n\n \n\n\n\n Estuarine and Coastal Marine Science. 1979.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{lipschultz_nitrogen_1979,\n\ttitle = {Nitrogen fixation associated with four species of submerged angiosperms in the central {Chesapeake} bay},\n\tdoi = {10.1016/S0302-3524(79)80014-6},\n\tabstract = {The rate of acetylene reduction was determined for Myriophyllum spicatum, Potamogeton perfoliatus, Ruppia maritima and Elodea canadensis, in a brackish water tributary of Chesapeake Bay. Ruppia had the highest nitrogen fixation rate on a dry weight basis [66 ng-at. N(g wt h)-1]. However the fixation per square meter of creek bottom was highest [16·3 μg-at. N(m2 h)-1] for Myriophyllum due to its greater biomass. Generally, our low rates are more comparable to those associated with seagrasses in North Carolina, than to many higher rates reported from tropical waters. We postulate that low nitrogen fixation rates are a consequence of the availability of nitrogen either in the water column or sediments of temperate estuaries such as the Chesapeake Bay, and the North Carolina Sounds. © 1979 Academic Press Inc. (London) Limited.},\n\tjournal = {Estuarine and Coastal Marine Science},\n\tauthor = {Lipschultz, Fredric and Cunningham, Jeffrey J. and Court Stevenson, J.},\n\tyear = {1979},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The rate of acetylene reduction was determined for Myriophyllum spicatum, Potamogeton perfoliatus, Ruppia maritima and Elodea canadensis, in a brackish water tributary of Chesapeake Bay. Ruppia had the highest nitrogen fixation rate on a dry weight basis [66 ng-at. N(g wt h)-1]. However the fixation per square meter of creek bottom was highest [16·3 μg-at. N(m2 h)-1] for Myriophyllum due to its greater biomass. Generally, our low rates are more comparable to those associated with seagrasses in North Carolina, than to many higher rates reported from tropical waters. We postulate that low nitrogen fixation rates are a consequence of the availability of nitrogen either in the water column or sediments of temperate estuaries such as the Chesapeake Bay, and the North Carolina Sounds. © 1979 Academic Press Inc. (London) Limited.\n
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\n \n\n \n \n \n \n \n Effect of nutrient enrichment on growth of the eelgrass Zostera marina in the Chesapeake Bay, Virginia, USA.\n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Marine Biology. 1977.\n \n\n\n\n
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@article{orth_effect_1977,\n\ttitle = {Effect of nutrient enrichment on growth of the eelgrass {Zostera} marina in the {Chesapeake} {Bay}, {Virginia}, {USA}},\n\tdoi = {10.1007/BF00386958},\n\tabstract = {The addition of two commerical fertilizers, one 5\\% NH4NO3, 10\\% P2O5, 10\\% K2O, and the other 10\\% NH4NO3, 10\\% P2O5, 10\\% K2O, ahd a dramatic effect on the growth of Zostera marina in the Chesapeake Bay. There was a significant increase in the length, biomass and total number of turions of fertilized plots compared with controls during a 2 to 3 month period. Data from this short-term field experiment suggest that Z. marina beds in the Chesapeake Bay are nutrient-limited, that the grwoth form of Z. marina may be related to the sediment nutrient supply, and that Z. marina may competitively exclude Ruppia maritima by light-shading. © 1977 Springer-Verlag.},\n\tjournal = {Marine Biology},\n\tauthor = {Orth, R. J.},\n\tyear = {1977},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The addition of two commerical fertilizers, one 5% NH4NO3, 10% P2O5, 10% K2O, and the other 10% NH4NO3, 10% P2O5, 10% K2O, ahd a dramatic effect on the growth of Zostera marina in the Chesapeake Bay. There was a significant increase in the length, biomass and total number of turions of fertilized plots compared with controls during a 2 to 3 month period. Data from this short-term field experiment suggest that Z. marina beds in the Chesapeake Bay are nutrient-limited, that the grwoth form of Z. marina may be related to the sediment nutrient supply, and that Z. marina may competitively exclude Ruppia maritima by light-shading. © 1977 Springer-Verlag.\n
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\n \n\n \n \n \n \n \n Temperature and rooted aquatic plants.\n \n \n \n\n\n \n Anderson, R. R.\n\n\n \n\n\n\n Chesapeake Science. 1969.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{anderson_temperature_1969,\n\ttitle = {Temperature and rooted aquatic plants},\n\tdoi = {10.2307/1350452},\n\tabstract = {In relation to the disappearance of a Ruppia maritima population near the effuent of an electrical generating station on the Patuxent River, Maryland, a broad study of temperature effects on respiration and photosynthesis of aquatic plants was begun. A Gilson differential respirometer was used to investigate respiratory variation in leaves of Potamogeton perfoliatus at 25, 30, 35, 40, and 45 C. This species grows with Ruppia maritima, appears to be more tolerant of high temperatures and plant material was readily available. Plants growing in heated and non-heated water were compared. The data indicate that P. perfoliatus is capable of physiological adjustment to higher temperatures as the leaf matures, since only older leaves tended to respire less at the elevated temperatures. Death of plant material occurred at 45 C. © 1969 Estuarine Research Federation.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Anderson, Richard R.},\n\tyear = {1969},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n In relation to the disappearance of a Ruppia maritima population near the effuent of an electrical generating station on the Patuxent River, Maryland, a broad study of temperature effects on respiration and photosynthesis of aquatic plants was begun. A Gilson differential respirometer was used to investigate respiratory variation in leaves of Potamogeton perfoliatus at 25, 30, 35, 40, and 45 C. This species grows with Ruppia maritima, appears to be more tolerant of high temperatures and plant material was readily available. Plants growing in heated and non-heated water were compared. The data indicate that P. perfoliatus is capable of physiological adjustment to higher temperatures as the leaf matures, since only older leaves tended to respire less at the elevated temperatures. Death of plant material occurred at 45 C. © 1969 Estuarine Research Federation.\n
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\n \n\n \n \n \n \n \n The Mineral Content of Myriophyllum Spicatum L. in Relation to Its Aquatic Environment.\n \n \n \n\n\n \n Anderson, R. R.; Brown, R. G.; and Rappleye, R. D.\n\n\n \n\n\n\n Ecology. 1966.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{anderson_mineral_1966,\n\ttitle = {The {Mineral} {Content} of {Myriophyllum} {Spicatum} {L}. in {Relation} to {Its} {Aquatic} {Environment}},\n\tdoi = {10.2307/1934270},\n\tabstract = {The mineral composition of Myriophyllum spicatum L. (Eurasian water-milfoil) and its aquatic environment were investigated to determine the relationship between ionic contents in the plant and in the water. Systematic samplings were made in several areas. The species was growing in a wide range of environmental situations. Normal-appearing specimens were collected at water temperatures ranging from 0.2 to 30 degrees C. Salinities varied from 0.05 to 16.4 ppt. Each of the estuarine collecting sites fluctuated about 7 ppt during the experimental period. The fresh-water pond varied between 0.05 and 0.20 ppt. The pH values ranged from 5.8 to 9.5 with alkaline waters predominating at four of the five collecting stations. M. spicatum was capable of regulating salt intake independent of concentrations in the aquatic environment.},\n\tjournal = {Ecology},\n\tauthor = {Anderson, Richard R. and Brown, Russell G. and Rappleye, Robert D.},\n\tyear = {1966},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The mineral composition of Myriophyllum spicatum L. (Eurasian water-milfoil) and its aquatic environment were investigated to determine the relationship between ionic contents in the plant and in the water. Systematic samplings were made in several areas. The species was growing in a wide range of environmental situations. Normal-appearing specimens were collected at water temperatures ranging from 0.2 to 30 degrees C. Salinities varied from 0.05 to 16.4 ppt. Each of the estuarine collecting sites fluctuated about 7 ppt during the experimental period. The fresh-water pond varied between 0.05 and 0.20 ppt. The pH values ranged from 5.8 to 9.5 with alkaline waters predominating at four of the five collecting stations. M. spicatum was capable of regulating salt intake independent of concentrations in the aquatic environment.\n
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\n \n\n \n \n \n \n \n Mineral composition of Eurasian water milfoil, Myriophyllum spicatum L.\n \n \n \n\n\n \n Anderson, R. R.; Brown, R. G.; and Rappleye, R. D.\n\n\n \n\n\n\n Chesapeake Science. 1965.\n \n\n\n\n
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\n 
@article{anderson_mineral_1965,\n\ttitle = {Mineral composition of {Eurasian} water milfoil, {Myriophyllum} spicatum {L}},\n\tdoi = {10.2307/1350625},\n\tabstract = {The mineral composition of the Eurasian water milfoil, Myriophyllum spicatum L., in Maryland was investigated to determine the feasibility of its use as a supplement or substitute for commercial fertilizer. From June 1962 to January 1963, samples were collected and analyzed from one freshwater and four estuarine habitats. Results indicate that m. spicatum would not be an economically feasible substitute for commercial fertilizer due to an 85–90\\% loss in weight upon drying and an N−P−K value of only 3-2-5. The plant grows in a wide range of environment. Specimens of normal appearance were collected at water temperatures ranging from 0.2 to 30.0°C, pH values from 5.8 to 9.5, and salinities from 0.07 to 16.4 ppt. Maximum salt tolerance of the plant appeared to be about 15 ppt. © 1965, Estuarine Research Federation. All rights reserved.},\n\tjournal = {Chesapeake Science},\n\tauthor = {Anderson, Richard R. and Brown, Russell G. and Rappleye, Robert D.},\n\tyear = {1965},\n\tkeywords = {Environmental Interactions, Processes, and Modeling},\n}\n\n
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\n The mineral composition of the Eurasian water milfoil, Myriophyllum spicatum L., in Maryland was investigated to determine the feasibility of its use as a supplement or substitute for commercial fertilizer. From June 1962 to January 1963, samples were collected and analyzed from one freshwater and four estuarine habitats. Results indicate that m. spicatum would not be an economically feasible substitute for commercial fertilizer due to an 85–90% loss in weight upon drying and an N−P−K value of only 3-2-5. The plant grows in a wide range of environment. Specimens of normal appearance were collected at water temperatures ranging from 0.2 to 30.0°C, pH values from 5.8 to 9.5, and salinities from 0.07 to 16.4 ppt. Maximum salt tolerance of the plant appeared to be about 15 ppt. © 1965, Estuarine Research Federation. All rights reserved.\n
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\n  \n Reproductive Biology, Systematics, and Molecular Genetics\n \n \n (38)\n \n \n
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\n \n\n \n \n \n \n \n Adaptations by Zostera marina dominated seagrass meadows in response towater quality and climate forcing.\n \n \n \n\n\n \n Shields, E. C.; Moore, K. A.; and Parrish, D. B.\n\n\n \n\n\n\n Diversity. 2018.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 1 download\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{shields_adaptations_2018,\n\ttitle = {Adaptations by {Zostera} marina dominated seagrass meadows in response towater quality and climate forcing},\n\tdoi = {10.3390/d10040125},\n\tabstract = {Global assessments of seagrass declines have documented accelerating rates of loss due to anthropogenic sediment and nutrient loadings, resulting in poor water quality. More recently, global temperature increases have emerged as additional major stressors. Seagrass changes in the Chesapeake Bay, USA provide important examples of not only the effects of human disturbance and climate forcing on seagrass loss, but also meadow recovery and resiliency. In the York River sub-tributary of the Chesapeake Bay, the meadows have been monitored intensively using annual aerial imagery, monthly transect surveys, and continuous water quality measurements. Here, Zostera marina has been demonstrating a shift in its historical growth patterns, with its biomass peaking earlier in the growing season and summer declines beginning earlier. We found an increasing trend in the length of the most stressful high temperature summer period, increasing by 22 days since 1950. Over the past 20 years, Z. marina's abundance has exhibited periods of decline followed by recovery, with recovery years associated with greater spring water clarity and less time spent at water temperatures {\\textbackslash}textgreater 28 °C. Although human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina.},\n\tjournal = {Diversity},\n\tauthor = {Shields, Erin C. and Moore, Kenneth A. and Parrish, David B.},\n\tyear = {2018},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Global assessments of seagrass declines have documented accelerating rates of loss due to anthropogenic sediment and nutrient loadings, resulting in poor water quality. More recently, global temperature increases have emerged as additional major stressors. Seagrass changes in the Chesapeake Bay, USA provide important examples of not only the effects of human disturbance and climate forcing on seagrass loss, but also meadow recovery and resiliency. In the York River sub-tributary of the Chesapeake Bay, the meadows have been monitored intensively using annual aerial imagery, monthly transect surveys, and continuous water quality measurements. Here, Zostera marina has been demonstrating a shift in its historical growth patterns, with its biomass peaking earlier in the growing season and summer declines beginning earlier. We found an increasing trend in the length of the most stressful high temperature summer period, increasing by 22 days since 1950. Over the past 20 years, Z. marina's abundance has exhibited periods of decline followed by recovery, with recovery years associated with greater spring water clarity and less time spent at water temperatures \\textgreater 28 °C. Although human disturbance and climatic factors have been altering these seagrass meadows, resilience has been evident by an increase in reproductive output and regrowth from Z. marina seedlings following declines, as well as expansions of Ruppia maritima into areas previously dominated by Z. marina.\n
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\n \n\n \n \n \n \n \n The influence of resource availability on flowering intensity in Zostera marina (L.).\n \n \n \n\n\n \n Johnson, A. J.; Moore, K. A.; and Orth, R. J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 2017.\n \n\n\n\n
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@article{johnson_influence_2017,\n\ttitle = {The influence of resource availability on flowering intensity in {Zostera} marina ({L}.)},\n\tdoi = {10.1016/j.jembe.2017.02.002},\n\tabstract = {The impact of resource availability on investment between asexual and sexual reproduction in seagrasses remains poorly understood. In this study, the effects of sediment nutrients and light availability on sexual and asexual reproduction in the seagrass Zostera marina (L.) were investigated. Field manipulations were combined with observational surveys to identify whether nutrient and light availability influenced flowering intensity of Z. marina in Chesapeake Bay, Virginia. A positive relationship between pore water ammonium and the percentage of flowering shoots was observed across locations with differing sediment nutrient types. In addition, short-term elevation of sediment nutrients increased the number of spathes per flowering shoot, but did not alter flowering shoot densities. Surveys around existing residential piers, used as observational surrogates for long-term shading, found seagrass directly below piers exhibited lower percentages of flower shoots than adjacent unshaded seagrass. In contrast, seasonal light reductions of seagrass did not significantly affect flowering intensity in experimental plots. Thus, increasing nutrient resources over both the seasonal and longer terms appeared to increase several aspects of investment in sexual reproduction, while only long-term reductions in shading decreased investment in sexual reproduction. Therefore, any factors which influence the duration and magnitude of nutrient and light resource availability to seagrass, may have important implications for the sustainability and resiliency of these valuable populations and the services they provide within increasingly threatened coastal systems.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Johnson, Andrew J. and Moore, Kenneth A. and Orth, Robert J.},\n\tyear = {2017},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n The impact of resource availability on investment between asexual and sexual reproduction in seagrasses remains poorly understood. In this study, the effects of sediment nutrients and light availability on sexual and asexual reproduction in the seagrass Zostera marina (L.) were investigated. Field manipulations were combined with observational surveys to identify whether nutrient and light availability influenced flowering intensity of Z. marina in Chesapeake Bay, Virginia. A positive relationship between pore water ammonium and the percentage of flowering shoots was observed across locations with differing sediment nutrient types. In addition, short-term elevation of sediment nutrients increased the number of spathes per flowering shoot, but did not alter flowering shoot densities. Surveys around existing residential piers, used as observational surrogates for long-term shading, found seagrass directly below piers exhibited lower percentages of flower shoots than adjacent unshaded seagrass. In contrast, seasonal light reductions of seagrass did not significantly affect flowering intensity in experimental plots. Thus, increasing nutrient resources over both the seasonal and longer terms appeared to increase several aspects of investment in sexual reproduction, while only long-term reductions in shading decreased investment in sexual reproduction. Therefore, any factors which influence the duration and magnitude of nutrient and light resource availability to seagrass, may have important implications for the sustainability and resiliency of these valuable populations and the services they provide within increasingly threatened coastal systems.\n
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\n \n\n \n \n \n \n \n Demographic and genetic connectivity: The role and consequences of reproduction, dispersal and recruitment in seagrasses.\n \n \n \n\n\n \n Kendrick, G. A.; Orth, R. J.; Statton, J.; Hovey, R.; Montoya, L. R.; Lowe, R. J.; Krauss, S. L.; and Sinclair, E. A.\n\n\n \n\n\n\n 2017.\n Publication Title: Biological Reviews\n\n\n\n
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@book{kendrick_demographic_2017,\n\ttitle = {Demographic and genetic connectivity: {The} role and consequences of reproduction, dispersal and recruitment in seagrasses},\n\tabstract = {Accurate estimation of connectivity among populations is fundamental for determining the drivers of population resilience, genetic diversity, adaptation and speciation. However the separation and quantification of contemporary versus historical connectivity remains a major challenge. This review focuses on marine angiosperms, seagrasses, that are fundamental to the health and productivity of temperate and tropical coastal marine environments globally. Our objective is to understand better the role of sexual reproduction and recruitment in influencing demographic and genetic connectivity among seagrass populations through an integrated multidisciplinary assessment of our present ecological, genetic, and demographic understanding, with hydrodynamic modelling of transport. We investigate (i) the demographic consequences of sexual reproduction, dispersal and recruitment in seagrasses, (ii) contemporary transport of seagrass pollen, fruits and seed, and vegetative fragments with a focus on hydrodynamic and particle transportmodels, and (iii) contemporary genetic connectivity among seagrass meadows as inferred through the application of genetic markers. New approaches are reviewed, followed by a summary outlining future directions for research: integrating seascape genetic approaches; incorporating hydrodynamic modelling for dispersal of pollen, seeds and vegetative fragments; integrating studies across broader geographic ranges; and incorporating non-equilibrium modelling. These approaches will lead to a more integrated understanding of the role of contemporary dispersal and recruitment in the persistence and evolution of seagrasses.},\n\tauthor = {Kendrick, Gary A. and Orth, Robert J. and Statton, John and Hovey, Renae and Montoya, Leonardo Ruiz and Lowe, Ryan J. and Krauss, Siegfried L. and Sinclair, Elizabeth A.},\n\tyear = {2017},\n\tdoi = {10.1111/brv.12261},\n\tnote = {Publication Title: Biological Reviews},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Accurate estimation of connectivity among populations is fundamental for determining the drivers of population resilience, genetic diversity, adaptation and speciation. However the separation and quantification of contemporary versus historical connectivity remains a major challenge. This review focuses on marine angiosperms, seagrasses, that are fundamental to the health and productivity of temperate and tropical coastal marine environments globally. Our objective is to understand better the role of sexual reproduction and recruitment in influencing demographic and genetic connectivity among seagrass populations through an integrated multidisciplinary assessment of our present ecological, genetic, and demographic understanding, with hydrodynamic modelling of transport. We investigate (i) the demographic consequences of sexual reproduction, dispersal and recruitment in seagrasses, (ii) contemporary transport of seagrass pollen, fruits and seed, and vegetative fragments with a focus on hydrodynamic and particle transportmodels, and (iii) contemporary genetic connectivity among seagrass meadows as inferred through the application of genetic markers. New approaches are reviewed, followed by a summary outlining future directions for research: integrating seascape genetic approaches; incorporating hydrodynamic modelling for dispersal of pollen, seeds and vegetative fragments; integrating studies across broader geographic ranges; and incorporating non-equilibrium modelling. These approaches will lead to a more integrated understanding of the role of contemporary dispersal and recruitment in the persistence and evolution of seagrasses.\n
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\n \n\n \n \n \n \n \n Submersed aquatic vegetation in chesapeake bay: Sentinel species in a changing world.\n \n \n \n\n\n \n Orth, R. J.; Dennison, W. C.; Lefcheck, J. S.; Gurbisz, C.; Hannam, M.; Keisman, J.; Landry, J. B.; Moore, K. A.; Murphy, R. R.; Patrick, C. J.; Testa, J.; Weller, D. E.; and Wilcox, D. J.\n\n\n \n\n\n\n 2017.\n Publication Title: BioScience\n\n\n\n
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@book{orth_submersed_2017,\n\ttitle = {Submersed aquatic vegetation in chesapeake bay: {Sentinel} species in a changing world},\n\tabstract = {Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.},\n\tauthor = {Orth, Robert J. and Dennison, William C. and Lefcheck, Jonathan S. and Gurbisz, Cassie and Hannam, Michael and Keisman, Jennifer and Landry, J. Brooke and Moore, Kenneth A. and Murphy, Rebecca R. and Patrick, Christopher J. and Testa, Jeremy and Weller, Donald E. and Wilcox, David J.},\n\tyear = {2017},\n\tdoi = {10.1093/biosci/bix058},\n\tnote = {Publication Title: BioScience},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.\n
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\n \n\n \n \n \n \n \n Temporal variability in potential connectivity of Vallisneria americana in the Chesapeake Bay.\n \n \n \n\n\n \n Lloyd, M. W.; Widmeyer, P. A.; and Neel, M. C.\n\n\n \n\n\n\n Landscape Ecology. 2016.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{lloyd_temporal_2016,\n\ttitle = {Temporal variability in potential connectivity of {Vallisneria} americana in the {Chesapeake} {Bay}},\n\tdoi = {10.1007/s10980-016-0401-y},\n\tabstract = {Context: Submersed aquatic vegetation (SAV) performs water quality enhancing functions that are critical to the overall health of estuaries such as the Chesapeake Bay. However, eutrophication and sedimentation have decimated the Bay's SAV population to a fraction of its historical coverage. Understanding the spatial distribution of and connectedness among patches is important for assessing the dynamics and health of the remaining SAV population. Objectives: We seek to explore the distribution of SAV patches and patterns of potential connectivity in the Chesapeake Bay through time. Methods: We assess critical distances, from complete patch isolation to connection of all patches, in a merged composite coverage map that represents the sum of all probable Vallisneria americana containing patches between 1984 and 2010 and in coverage maps for individual years within that timeframe for which complete survey data are available. Results: We have three key findings: First, the amount of SAV coverage in any given year is much smaller than the total recently occupied acreage. Second, the vast majority of patches of SAV that are within the tolerances of V. americana are ephemeral, being observed in only 1 or 2 years out of 26 years. Third, this high patch turnover results in highly variable connectivity from year to year, dependent on dispersal distance and patch arrangement. Conclusions: Most of the connectivity thresholds are beyond reasonable dispersal distances for V. americana. If the high turnover in habitat occupancy is due to marginal water quality, relatively small improvements could greatly increase V. americana growth and persistence.},\n\tjournal = {Landscape Ecology},\n\tauthor = {Lloyd, Michael W. and Widmeyer, Paul A. and Neel, Maile C.},\n\tyear = {2016},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Context: Submersed aquatic vegetation (SAV) performs water quality enhancing functions that are critical to the overall health of estuaries such as the Chesapeake Bay. However, eutrophication and sedimentation have decimated the Bay's SAV population to a fraction of its historical coverage. Understanding the spatial distribution of and connectedness among patches is important for assessing the dynamics and health of the remaining SAV population. Objectives: We seek to explore the distribution of SAV patches and patterns of potential connectivity in the Chesapeake Bay through time. Methods: We assess critical distances, from complete patch isolation to connection of all patches, in a merged composite coverage map that represents the sum of all probable Vallisneria americana containing patches between 1984 and 2010 and in coverage maps for individual years within that timeframe for which complete survey data are available. Results: We have three key findings: First, the amount of SAV coverage in any given year is much smaller than the total recently occupied acreage. Second, the vast majority of patches of SAV that are within the tolerances of V. americana are ephemeral, being observed in only 1 or 2 years out of 26 years. Third, this high patch turnover results in highly variable connectivity from year to year, dependent on dispersal distance and patch arrangement. Conclusions: Most of the connectivity thresholds are beyond reasonable dispersal distances for V. americana. If the high turnover in habitat occupancy is due to marginal water quality, relatively small improvements could greatly increase V. americana growth and persistence.\n
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\n \n\n \n \n \n \n \n Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems.\n \n \n \n\n\n \n Govers, L. L.; Man In ‘T Veld, W. A.; Meffert, J. P.; Bouma, T. J.; van Rijswick, P. C.; Heusinkveld, J. H.; Orth, R. J.; van Katwijk, M. M.; and van der Heide, T.\n\n\n \n\n\n\n Proceedings of the Royal Society B: Biological Sciences. 2016.\n \n\n\n\n
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@article{govers_marine_2016,\n\ttitle = {Marine {Phytophthora} species can hamper conservation and restoration of vegetated coastal ecosystems},\n\tdoi = {10.1098/rspb.2016.0812},\n\tabstract = {Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp. Zostera, P. gemini, or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts.},\n\tjournal = {Proceedings of the Royal Society B: Biological Sciences},\n\tauthor = {Govers, Laura L. and Man In ‘T Veld, Willem A. and Meffert, Johan P. and Bouma, Tjeerd J. and van Rijswick, Patricia C.J. and Heusinkveld, Jannes H.T. and Orth, Robert J. and van Katwijk, Marieke M. and van der Heide, Tjisse},\n\tyear = {2016},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Phytophthora species are potent pathogens that can devastate terrestrial plants, causing billions of dollars of damage yearly to agricultural crops and harming fragile ecosystems worldwide. Yet, virtually nothing is known about the distribution and pathogenicity of their marine relatives. This is surprising, as marine plants form vital habitats in coastal zones worldwide (i.e. mangrove forests, salt marshes, seagrass beds), and disease may be an important bottleneck for the conservation and restoration of these rapidly declining ecosystems. We are the first to report on widespread infection of Phytophthora and Halophytophthora species on a common seagrass species, Zostera marina (eelgrass), across the northern Atlantic and Mediterranean. In addition, we tested the effects of Halophytophthora sp. Zostera and Phytophthora gemini on Z. marina seed germination in a full-factorial laboratory experiment under various environmental conditions. Results suggest that Phytophthora species are widespread as we found these oomycetes in eelgrass beds in six countries across the North Atlantic and Mediterranean. Infection by Halophytophthora sp. Zostera, P. gemini, or both, strongly affected sexual reproduction by reducing seed germination sixfold. Our findings have important implications for seagrass ecology, because these putative pathogens probably negatively affect ecosystem functioning, as well as current restoration and conservation efforts.\n
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\n \n\n \n \n \n \n \n Effects of Seed Source, Sediment Type, and Burial Depth on Mixed-Annual and Perennial Zostera marina L. Seed Germination and Seedling Establishment.\n \n \n \n\n\n \n Jarvis, J. C.; and Moore, K. A.\n\n\n \n\n\n\n Estuaries and Coasts. 2015.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{jarvis_effects_2015,\n\ttitle = {Effects of {Seed} {Source}, {Sediment} {Type}, and {Burial} {Depth} on {Mixed}-{Annual} and {Perennial} {Zostera} marina {L}. {Seed} {Germination} and {Seedling} {Establishment}},\n\tdoi = {10.1007/s12237-014-9869-3},\n\tabstract = {Seed germination and seedling establishment directly affect the resiliency of seagrasses to disturbance or environmental stress. The objectives of this study were to compare maximum seed germination, time to germination, nongerminated seed viability, and initial seedling biomass between mixed-annual and perennial Zostera marina seed populations in coarse ({\\textbackslash}textgreater90 \\% sand) and fine ({\\textbackslash}textless50 \\% sand) sediments and at shallow (1 cm) and deep (5 cm) burial depths. Perennial seeds collected from Virginia and North Carolina had greater maximum germination, shorter time to germination, and greater seedling biomass compared to mixed-annual seeds collected from North Carolina. For both mixed-annual and perennial seeds, maximum germination and seedling biomass were the greatest in shallow fine sediments. Mixed-annual seeds buried at 1 cm had a shorter time to germination than in the deep treatments; however, sediment type did not affect mean time to germination. Perennial seeds had a shorter time to germination in shallow compared to deep burial depths and in fine compared to coarse sediments. Cues for germination were present at the deeper depths; however, the cotyledon failed to emerge from the sediment surface resulting in mortality at depths of 5 cm. The greater performance of perennial compared to mixed-annual seeds and seedlings demonstrate the trade-offs which can occur between Z. marina reproductive strategies. Reduced germination of Z. marina seeds buried ≥5 cm and in coarse sediments may represent a possible bottleneck in successful sexual reproduction, feasibly affecting the resiliency to and recovery from disturbance for both perennial and mixed-annual Z. marina beds.},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Jarvis, Jessie C. and Moore, Kenneth A.},\n\tyear = {2015},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Seed germination and seedling establishment directly affect the resiliency of seagrasses to disturbance or environmental stress. The objectives of this study were to compare maximum seed germination, time to germination, nongerminated seed viability, and initial seedling biomass between mixed-annual and perennial Zostera marina seed populations in coarse (\\textgreater90 % sand) and fine (\\textless50 % sand) sediments and at shallow (1 cm) and deep (5 cm) burial depths. Perennial seeds collected from Virginia and North Carolina had greater maximum germination, shorter time to germination, and greater seedling biomass compared to mixed-annual seeds collected from North Carolina. For both mixed-annual and perennial seeds, maximum germination and seedling biomass were the greatest in shallow fine sediments. Mixed-annual seeds buried at 1 cm had a shorter time to germination than in the deep treatments; however, sediment type did not affect mean time to germination. Perennial seeds had a shorter time to germination in shallow compared to deep burial depths and in fine compared to coarse sediments. Cues for germination were present at the deeper depths; however, the cotyledon failed to emerge from the sediment surface resulting in mortality at depths of 5 cm. The greater performance of perennial compared to mixed-annual seeds and seedlings demonstrate the trade-offs which can occur between Z. marina reproductive strategies. Reduced germination of Z. marina seeds buried ≥5 cm and in coarse sediments may represent a possible bottleneck in successful sexual reproduction, feasibly affecting the resiliency to and recovery from disturbance for both perennial and mixed-annual Z. marina beds.\n
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\n \n\n \n \n \n \n \n Modeling loss and recovery of Zostera marina beds in the Chesapeake Bay: The role of seedlings and seed-bank viability.\n \n \n \n\n\n \n Jarvis, J. C.; Brush, M. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{jarvis_modeling_2014,\n\ttitle = {Modeling loss and recovery of {Zostera} marina beds in the {Chesapeake} {Bay}: {The} role of seedlings and seed-bank viability},\n\tdoi = {10.1016/j.aquabot.2013.10.010},\n\tabstract = {Loss and recovery processes following a documented large scale decline in Zostera marina beds in the York River, Virginia in 2005 were modeled by coupling production and sexual reproduction models. The reproduction model included formulations for reproductive shoot production, seed production, seed-bank density, seed viability, and seed germination. After the model was calibrated and validated using in situ water quality and plant performance measurements from two different sites, model scenarios were run for three years (1 year pre-decline, 2 years post-decline) to quantify the effects of (1) the presence or absence of sexual reproduction, (2) increases in water temperatures from ambient to ambient +5. °C in 1. °C increments, and (3) the potential interactive effects of light and temperature conditions on bed maintenance and re-establishment. Model projections of Z. marina production following the decline corresponded to in situ measurements of recovery only when sexual reproduction was added. However, a 1. °C increase in temperature resulted in a complete loss of biomass after two consecutive years of temperature stress following the depletion of the viable sediment seed bank. Interactions between light and temperature stress resulted in overall lower production and resilience to declines under lower light conditions due to corresponding decreases in photosynthetic rates and increases in respiration. Model results highlight (1) the need to incorporate sexual reproduction into Z. marina ecosystem models, (2) the projected sensitivity of established beds to consecutive years of stress, and (3) the negative effects of multiple stressors on Z. marina resilience and recovery. © 2013 Elsevier B.V.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Jarvis, Jessie C. and Brush, Mark J. and Moore, Kenneth A.},\n\tyear = {2014},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Loss and recovery processes following a documented large scale decline in Zostera marina beds in the York River, Virginia in 2005 were modeled by coupling production and sexual reproduction models. The reproduction model included formulations for reproductive shoot production, seed production, seed-bank density, seed viability, and seed germination. After the model was calibrated and validated using in situ water quality and plant performance measurements from two different sites, model scenarios were run for three years (1 year pre-decline, 2 years post-decline) to quantify the effects of (1) the presence or absence of sexual reproduction, (2) increases in water temperatures from ambient to ambient +5. °C in 1. °C increments, and (3) the potential interactive effects of light and temperature conditions on bed maintenance and re-establishment. Model projections of Z. marina production following the decline corresponded to in situ measurements of recovery only when sexual reproduction was added. However, a 1. °C increase in temperature resulted in a complete loss of biomass after two consecutive years of temperature stress following the depletion of the viable sediment seed bank. Interactions between light and temperature stress resulted in overall lower production and resilience to declines under lower light conditions due to corresponding decreases in photosynthetic rates and increases in respiration. Model results highlight (1) the need to incorporate sexual reproduction into Z. marina ecosystem models, (2) the projected sensitivity of established beds to consecutive years of stress, and (3) the negative effects of multiple stressors on Z. marina resilience and recovery. © 2013 Elsevier B.V.\n
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\n \n\n \n \n \n \n \n Evidence of eelgrass (Zostera marina) seed dispersal by northern diamondback terrapin (Malaclemys terrapin terrapin) in lower Chesapeake Bay.\n \n \n \n\n\n \n Tulipani, D. C.; and Lipcius, R. N.\n\n\n \n\n\n\n PLoS ONE. 2014.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{tulipani_evidence_2014,\n\ttitle = {Evidence of eelgrass ({Zostera} marina) seed dispersal by northern diamondback terrapin ({Malaclemys} terrapin terrapin) in lower {Chesapeake} {Bay}},\n\tdoi = {10.1371/journal.pone.0103346},\n\tabstract = {The initial discovery in May 2009 of eelgrass (Zostera marina) seeds in fecal samples of wild-caught northern diamondback terrapins ( Malaclemys terrapin terrapin) was the first field evidence of eelgrass seed ingestion in this species. This finding suggested the potential of terrapins as seed dispersers in eelgrass beds, which we sampled for two additional years (2010 and 2011). Seeds were only found in feces of terrapins captured prior to June 8 in all three years, coinciding with eelgrass seed maturation and release. Numbers of seeds in terrapin feces varied annually and decreased greatly in 2011 after an eelgrass die off in late 2010. The condition of seeds in terrapin feces was viable-mature, germinated, damaged, or immature. Of terrapins captured during time of seed release, 97\\% were males and juvenile females, both of which had head widths {\\textbackslash}textless 30 mm. The fraction of individuals with ingested seeds was 33\\% for males, 35\\% for small females, and only 6\\% for large (mature) females. Probability of seed ingestion decreased exponentially with increasing terrapin head width; only males and small females (head width {\\textbackslash}textless30 mm) were likely to be vectors of seed dispersal. The characteristic that diamondback terrapins have well-defined home ranges allowed us to estimate the number of terrapins potentially dispersing eelgrass seeds annually. In seagrass beds of the Goodwin Islands region (lower York River, Virginia), there were 559 to 799 terrapins, which could disperse between 1,341 and 1,677 eelgrass seeds annually. These would represent a small proportion of total seed production within a single seagrass bed. However, based on probable home range distances, terrapins can easily traverse eelgrass meadow boundaries, thereby dispersing seeds beyond the bed of origin. Given the relatively short dispersion distance of eelgrass seeds, the diamondback terrapin may be a major source of inter-bed seed dispersal and genetic diversity. © 2014 Tulipani, Lipcius.},\n\tjournal = {PLoS ONE},\n\tauthor = {Tulipani, Diane C. and Lipcius, Romuald N.},\n\tyear = {2014},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n The initial discovery in May 2009 of eelgrass (Zostera marina) seeds in fecal samples of wild-caught northern diamondback terrapins ( Malaclemys terrapin terrapin) was the first field evidence of eelgrass seed ingestion in this species. This finding suggested the potential of terrapins as seed dispersers in eelgrass beds, which we sampled for two additional years (2010 and 2011). Seeds were only found in feces of terrapins captured prior to June 8 in all three years, coinciding with eelgrass seed maturation and release. Numbers of seeds in terrapin feces varied annually and decreased greatly in 2011 after an eelgrass die off in late 2010. The condition of seeds in terrapin feces was viable-mature, germinated, damaged, or immature. Of terrapins captured during time of seed release, 97% were males and juvenile females, both of which had head widths \\textless 30 mm. The fraction of individuals with ingested seeds was 33% for males, 35% for small females, and only 6% for large (mature) females. Probability of seed ingestion decreased exponentially with increasing terrapin head width; only males and small females (head width \\textless30 mm) were likely to be vectors of seed dispersal. The characteristic that diamondback terrapins have well-defined home ranges allowed us to estimate the number of terrapins potentially dispersing eelgrass seeds annually. In seagrass beds of the Goodwin Islands region (lower York River, Virginia), there were 559 to 799 terrapins, which could disperse between 1,341 and 1,677 eelgrass seeds annually. These would represent a small proportion of total seed production within a single seagrass bed. However, based on probable home range distances, terrapins can easily traverse eelgrass meadow boundaries, thereby dispersing seeds beyond the bed of origin. Given the relatively short dispersion distance of eelgrass seeds, the diamondback terrapin may be a major source of inter-bed seed dispersal and genetic diversity. © 2014 Tulipani, Lipcius.\n
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\n \n\n \n \n \n \n \n Restoration recovers population structure and landscape genetic connectivity in a dispersal-limited ecosystem.\n \n \n \n\n\n \n Reynolds, L. K.; Waycott, M.; and Mcglathery, K. J.\n\n\n \n\n\n\n Journal of Ecology. 2013.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{reynolds_restoration_2013,\n\ttitle = {Restoration recovers population structure and landscape genetic connectivity in a dispersal-limited ecosystem},\n\tdoi = {10.1111/1365-2745.12116},\n\tabstract = {Ecological restoration assists the recovery of degraded ecosystems; however, restoration can have deleterious effects such as outbreeding depression when source material is not chosen carefully and has non-local adaptations. We surveyed 23 eelgrass (Zostera marina L.) populations along the North American Atlantic coast to evaluate genetic structure and connectivity among restored and naturally recruited populations. While populations along the North America Atlantic coast were genetically distinctive, significant migration was detected among populations. All estimates of connectivity (FST, migration rate base on rare alleles, and Bayesian modelling) showed a general north to south pattern of migration, corresponding to the typical long-shore currents in this region. Individual naturally recruited meadows in the Virginia coastal bays appear to be the result of dispersal from different meadows north of the region. This supports the hypothesis that recruitment into this region is typically a slow, episodic process rather than a permanent, continuous connection between the populations. While natural recovery of populations that were catastrophically lost in the 1930s has been slow, large-scale seed-based restoration has been very successful at quickly restoring landscape-scale areal coverage (over 1600 ha in just 10 years). Our results show that restoration was also successful at restoring meadows with high genetic diversity. Naturally recruited meadows were less diverse and exhibited signs of genetic drift. Synthesis. Our analyses demonstrate that metapopulation dynamics are important to the natural recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales; however, natural recovery processes are slow and inefficient at recovering genetic diversity and population structure when recruitment barriers exist, such as a limited seed source. Seed-based restoration provides a greater abundance of propagules, rapidly facilitates the recovery of populations with higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. First-order estimates indicated that the genetic diversity achieved by active restoration in 10 years would have otherwise taken between 125 and 185 years to achieve through natural recruitment events. We demonstrate that metapopulations are important to recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales. However, natural recovery is slow and inefficient at recovering genetic diversity when recruitment barriers exist. Seed-based restoration rapidly facilitates the recovery of populations to higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. © 2013 British Ecological Society.},\n\tjournal = {Journal of Ecology},\n\tauthor = {Reynolds, Laura K. and Waycott, Michelle and Mcglathery, Karen J.},\n\tyear = {2013},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n\n\n
\n Ecological restoration assists the recovery of degraded ecosystems; however, restoration can have deleterious effects such as outbreeding depression when source material is not chosen carefully and has non-local adaptations. We surveyed 23 eelgrass (Zostera marina L.) populations along the North American Atlantic coast to evaluate genetic structure and connectivity among restored and naturally recruited populations. While populations along the North America Atlantic coast were genetically distinctive, significant migration was detected among populations. All estimates of connectivity (FST, migration rate base on rare alleles, and Bayesian modelling) showed a general north to south pattern of migration, corresponding to the typical long-shore currents in this region. Individual naturally recruited meadows in the Virginia coastal bays appear to be the result of dispersal from different meadows north of the region. This supports the hypothesis that recruitment into this region is typically a slow, episodic process rather than a permanent, continuous connection between the populations. While natural recovery of populations that were catastrophically lost in the 1930s has been slow, large-scale seed-based restoration has been very successful at quickly restoring landscape-scale areal coverage (over 1600 ha in just 10 years). Our results show that restoration was also successful at restoring meadows with high genetic diversity. Naturally recruited meadows were less diverse and exhibited signs of genetic drift. Synthesis. Our analyses demonstrate that metapopulation dynamics are important to the natural recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales; however, natural recovery processes are slow and inefficient at recovering genetic diversity and population structure when recruitment barriers exist, such as a limited seed source. Seed-based restoration provides a greater abundance of propagules, rapidly facilitates the recovery of populations with higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. First-order estimates indicated that the genetic diversity achieved by active restoration in 10 years would have otherwise taken between 125 and 185 years to achieve through natural recruitment events. We demonstrate that metapopulations are important to recovery of seagrass ecosystems that have experienced catastrophic loss over large spatial scales. However, natural recovery is slow and inefficient at recovering genetic diversity when recruitment barriers exist. Seed-based restoration rapidly facilitates the recovery of populations to higher genetic diversity, and when seed sources are chosen carefully protects regional genetic structure. © 2013 British Ecological Society.\n
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\n \n\n \n \n \n \n \n Potential roles of Labyrinthula spp. in global seagrass population declines.\n \n \n \n\n\n \n Sullivan, B. K.; Sherman, T. D.; Damare, V. S.; Lilje, O.; and Gleason, F. H.\n\n\n \n\n\n\n 2013.\n Publication Title: Fungal Ecology\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{sullivan_potential_2013,\n\ttitle = {Potential roles of {Labyrinthula} spp. in global seagrass population declines},\n\tabstract = {Overwhelming evidence suggests that seagrass ecosystems are declining around the world. Pathogens from the genus Labyrinthula have repeatedly been found to cause disease in a variety of seagrass species. For example, the 'wasting disease' of Zostera marina has been attributed to Labyrinthula infection. Although poorly characterized taxonomically, species of Labyrinthula are very common in marine ecosystems, virulence of genotypes/phylotypes is known to be variable, and highly virulent species are able to cause ecologically significant diseases of protists, plants and animals. Here, the pathosystem model is applied to host-parasite relationships in seagrass ecosystems. Known physical and biological stressors of seagrass are reviewed. Finally, we make the case that it is time to expand research on this poorly studied microorganism in order to quantify the role of disease in seagrass populations world-wide. © 2013 Elsevier Ltd and The British Mycological Society.},\n\tauthor = {Sullivan, Brooke K. and Sherman, Timothy D. and Damare, Varada S. and Lilje, Osu and Gleason, Frank H.},\n\tyear = {2013},\n\tdoi = {10.1016/j.funeco.2013.06.004},\n\tnote = {Publication Title: Fungal Ecology},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Overwhelming evidence suggests that seagrass ecosystems are declining around the world. Pathogens from the genus Labyrinthula have repeatedly been found to cause disease in a variety of seagrass species. For example, the 'wasting disease' of Zostera marina has been attributed to Labyrinthula infection. Although poorly characterized taxonomically, species of Labyrinthula are very common in marine ecosystems, virulence of genotypes/phylotypes is known to be variable, and highly virulent species are able to cause ecologically significant diseases of protists, plants and animals. Here, the pathosystem model is applied to host-parasite relationships in seagrass ecosystems. Known physical and biological stressors of seagrass are reviewed. Finally, we make the case that it is time to expand research on this poorly studied microorganism in order to quantify the role of disease in seagrass populations world-wide. © 2013 Elsevier Ltd and The British Mycological Society.\n
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\n \n\n \n \n \n \n \n Seedling establishment in eelgrass: Seed burial effects on winter losses of developing seedlings.\n \n \n \n\n\n \n Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{marion_seedling_2012,\n\ttitle = {Seedling establishment in eelgrass: {Seed} burial effects on winter losses of developing seedlings},\n\tdoi = {10.3354/meps09612},\n\tabstract = {Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked in separate destructively-sampled plots. Sediment height change was measured, and sediment disturbance depth was estimated by deploying cores layered with tracer particles and examining tracer loss upon core retrieval. We found a low rate of seedling establishment 6 mo after seeding (1.2, 3.8, and 2.8\\% for surface seeds at the 3 sites) that was largely due to seed and seedling loss rather than to germination failure, with 90\\% of seeds retrieved after December having germinated. Seed burial significantly enhanced seedling establishment at 2 of 3 sites (40.4, 16.8, and 10.3\\% establishment for buried seeds). Seed loss occurred mostly within the first month of the experiment, and was most severe for seeds at the sediment surface. Indicator core results showed widespread disturbance of sediments to depths that could have dislodged early seedlings developing from surface seeds, and to a lesser degree seedlings from buried seeds. Our findings help identify the nature and timing of a substantial Z. marina seedling establishment bottleneck in our region, and show that some of the key processes pivotal to Z. marina recruitment dynamics and optimal res - toration strategies involve physical sediment-seedling interactions rather than seed germination. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Marion, Scott R. and Orth, Robert J.},\n\tyear = {2012},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked in separate destructively-sampled plots. Sediment height change was measured, and sediment disturbance depth was estimated by deploying cores layered with tracer particles and examining tracer loss upon core retrieval. We found a low rate of seedling establishment 6 mo after seeding (1.2, 3.8, and 2.8% for surface seeds at the 3 sites) that was largely due to seed and seedling loss rather than to germination failure, with 90% of seeds retrieved after December having germinated. Seed burial significantly enhanced seedling establishment at 2 of 3 sites (40.4, 16.8, and 10.3% establishment for buried seeds). Seed loss occurred mostly within the first month of the experiment, and was most severe for seeds at the sediment surface. Indicator core results showed widespread disturbance of sediments to depths that could have dislodged early seedlings developing from surface seeds, and to a lesser degree seedlings from buried seeds. Our findings help identify the nature and timing of a substantial Z. marina seedling establishment bottleneck in our region, and show that some of the key processes pivotal to Z. marina recruitment dynamics and optimal res - toration strategies involve physical sediment-seedling interactions rather than seed germination. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n The Central Role of Dispersal in the Maintenance and Persistence of Seagrass Populations.\n \n \n \n\n\n \n Kendrick, G. A.; Waycott, M.; Carruthers, T. J. B.; Cambridge, M. L.; Hovey, R.; Krauss, S. L.; Lavery, P. S.; Les, D. H.; Lowe, R. J.; Vidal, O. M. i; Ooi, J. L. S.; Orth, R. J.; Rivers, D. O.; Ruiz-Montoya, L.; Sinclair, E. A.; Statton, J.; van Dijk, J. K.; and Verduin, J. J.\n\n\n \n\n\n\n BioScience. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
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@article{kendrick_central_2012,\n\ttitle = {The {Central} {Role} of {Dispersal} in the {Maintenance} and {Persistence} of {Seagrass} {Populations}},\n\tdoi = {10.1525/bio.2012.62.1.10},\n\tabstract = {Global seagrass losses parallel significant declines observed in corals and mangroves over the past 50 years. These combined declines have resulted in accelerated global losses to ecosystem services in coastal waters. Seagrass meadows can be extensive (hundreds of square kilometers) and long-lived (thousands of years), with the meadows persisting predominantly through vegetative (clonal) growth. They also invest a large amount of energy in sexual reproduction. In this article, we explore the role that sexual reproduction, pollen, and seed dispersal play in maintaining species distributions, genetic diversity, and connectivity among seagrass populations. We also address the relationship between long-distance dispersal, genetic connectivity, and the maintenance of genetic diversity that may enhance resilience to stresses associated with seagrass loss. Our reevaluation of seagrass dispersal and recruitment has altered our perception of the importance of long-distance dispersal and has revealed extensive dispersal at scales much larger than was previously thought possible. © 2012 by American Institute of Biological Sciences. All rights reserved.},\n\tjournal = {BioScience},\n\tauthor = {Kendrick, Gary A. and Waycott, Michelle and Carruthers, Tim J. B. and Cambridge, Marion L. and Hovey, Renae and Krauss, Siegfried L. and Lavery, Paul S. and Les, Donald H. and Lowe, Ryan J. and Vidal, Oriol Mascaró i and Ooi, Jillian L. S. and Orth, Robert J. and Rivers, David O. and Ruiz-Montoya, Leonardo and Sinclair, Elizabeth A. and Statton, John and van Dijk, Jent Kornelis and Verduin, Jennifer J.},\n\tyear = {2012},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Global seagrass losses parallel significant declines observed in corals and mangroves over the past 50 years. These combined declines have resulted in accelerated global losses to ecosystem services in coastal waters. Seagrass meadows can be extensive (hundreds of square kilometers) and long-lived (thousands of years), with the meadows persisting predominantly through vegetative (clonal) growth. They also invest a large amount of energy in sexual reproduction. In this article, we explore the role that sexual reproduction, pollen, and seed dispersal play in maintaining species distributions, genetic diversity, and connectivity among seagrass populations. We also address the relationship between long-distance dispersal, genetic connectivity, and the maintenance of genetic diversity that may enhance resilience to stresses associated with seagrass loss. Our reevaluation of seagrass dispersal and recruitment has altered our perception of the importance of long-distance dispersal and has revealed extensive dispersal at scales much larger than was previously thought possible. © 2012 by American Institute of Biological Sciences. All rights reserved.\n
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\n \n\n \n \n \n \n \n Genetic diversity enhances restoration success by augmenting ecosystem services.\n \n \n \n\n\n \n Reynolds, L. K.; McGlathery, K. J.; and Waycott, M.\n\n\n \n\n\n\n PLoS ONE. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{reynolds_genetic_2012,\n\ttitle = {Genetic diversity enhances restoration success by augmenting ecosystem services},\n\tdoi = {10.1371/journal.pone.0038397},\n\tabstract = {Disturbance and habitat destruction due to human activities is a pervasive problem in near-shore marine ecosystems, and restoration is often used to mitigate losses. A common metric used to evaluate the success of restoration is the return of ecosystem services. Previous research has shown that biodiversity, including genetic diversity, is positively associated with the provision of ecosystem services. We conducted a restoration experiment using sources, techniques, and sites similar to actual large-scale seagrass restoration projects and demonstrated that a small increase in genetic diversity enhanced ecosystem services (invertebrate habitat, increased primary productivity, and nutrient retention). In our experiment, plots with elevated genetic diversity had plants that survived longer, increased in density more quickly, and provided more ecosystem services (invertebrate habitat, increased primary productivity, and nutrient retention). We used the number of alleles per locus as a measure of genetic diversity, which, unlike clonal diversity used in earlier research, can be applied to any organism. Additionally, unlike previous studies where positive impacts of diversity occurred only after a large disturbance, this study assessed the importance of diversity in response to potential environmental stresses (high temperature, low light) along a water-depth gradient. We found a positive impact of diversity along the entire depth gradient. Taken together, these results suggest that ecosystem restoration will significantly benefit from obtaining sources (transplants or seeds) with high genetic diversity and from restoration techniques that can maintain that genetic diversity. © 2012 Reynolds et al.},\n\tjournal = {PLoS ONE},\n\tauthor = {Reynolds, Laura K. and McGlathery, Karen J. and Waycott, Michelle},\n\tyear = {2012},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Disturbance and habitat destruction due to human activities is a pervasive problem in near-shore marine ecosystems, and restoration is often used to mitigate losses. A common metric used to evaluate the success of restoration is the return of ecosystem services. Previous research has shown that biodiversity, including genetic diversity, is positively associated with the provision of ecosystem services. We conducted a restoration experiment using sources, techniques, and sites similar to actual large-scale seagrass restoration projects and demonstrated that a small increase in genetic diversity enhanced ecosystem services (invertebrate habitat, increased primary productivity, and nutrient retention). In our experiment, plots with elevated genetic diversity had plants that survived longer, increased in density more quickly, and provided more ecosystem services (invertebrate habitat, increased primary productivity, and nutrient retention). We used the number of alleles per locus as a measure of genetic diversity, which, unlike clonal diversity used in earlier research, can be applied to any organism. Additionally, unlike previous studies where positive impacts of diversity occurred only after a large disturbance, this study assessed the importance of diversity in response to potential environmental stresses (high temperature, low light) along a water-depth gradient. We found a positive impact of diversity along the entire depth gradient. Taken together, these results suggest that ecosystem restoration will significantly benefit from obtaining sources (transplants or seeds) with high genetic diversity and from restoration techniques that can maintain that genetic diversity. © 2012 Reynolds et al.\n
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\n \n\n \n \n \n \n \n Eelgrass restoration by seed maintains genetic diversity: Case study from a coastal bay system.\n \n \n \n\n\n \n Reynolds, L. K.; Waycott, M.; McGlathery, K. J.; Orth, R. J.; and Zieman, J. C.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{reynolds_eelgrass_2012,\n\ttitle = {Eelgrass restoration by seed maintains genetic diversity: {Case} study from a coastal bay system},\n\tdoi = {10.3354/meps09386},\n\tabstract = {Genetic diversity is positively associated with plant fitness, stability, and the provision of ecosystem services. Preserving genetic diversity is therefore considered an important component of ecosystem restoration as well as a measure of its success. We examined the genetic diversity of restored Zostera marina meadows in a coastal bay system along the USA mid-Atlantic coast using microsatellite markers to compare donor and recipient meadows. We show that donor meadows in Chesapeake Bay have high genetic diversity and that this diversity is maintained in meadows restored with seeds in the Virginia coastal bays. No evidence of inbreeding depression was detected (F IS -0.2 to 0) in either donor or recipient meadows, which is surprising because high levels of inbreeding were expected following the population contractions that occurred in Chesapeake Bay populations due to disease and heat stress. Additionally, there was no evidence for selection of genotypes at the restoration sites, suggesting that as long as donor sites are chosen carefully, issues that diminish fitness and survival such as heterosis or out-breeding depression can be avoided. A cluster analysis showed that, in addition to the Chesapeake Bay populations that acted as donors, the Virginia coastal bay populations shared a genetic signal with Chincoteague Bay populations, their closest neighbor to the north, suggesting that natural recruitment into the area may be occurring and augmenting restored populations. We hypothesize that the high genetic diversity in seagrasses restored using seeds rather than adult plants confers a greater level of ecosystem resilience to the restored meadows. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Reynolds, Laura K. and Waycott, Michelle and McGlathery, Karen J. and Orth, Robert J. and Zieman, Joseph C.},\n\tyear = {2012},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Genetic diversity is positively associated with plant fitness, stability, and the provision of ecosystem services. Preserving genetic diversity is therefore considered an important component of ecosystem restoration as well as a measure of its success. We examined the genetic diversity of restored Zostera marina meadows in a coastal bay system along the USA mid-Atlantic coast using microsatellite markers to compare donor and recipient meadows. We show that donor meadows in Chesapeake Bay have high genetic diversity and that this diversity is maintained in meadows restored with seeds in the Virginia coastal bays. No evidence of inbreeding depression was detected (F IS -0.2 to 0) in either donor or recipient meadows, which is surprising because high levels of inbreeding were expected following the population contractions that occurred in Chesapeake Bay populations due to disease and heat stress. Additionally, there was no evidence for selection of genotypes at the restoration sites, suggesting that as long as donor sites are chosen carefully, issues that diminish fitness and survival such as heterosis or out-breeding depression can be avoided. A cluster analysis showed that, in addition to the Chesapeake Bay populations that acted as donors, the Virginia coastal bay populations shared a genetic signal with Chincoteague Bay populations, their closest neighbor to the north, suggesting that natural recruitment into the area may be occurring and augmenting restored populations. We hypothesize that the high genetic diversity in seagrasses restored using seeds rather than adult plants confers a greater level of ecosystem resilience to the restored meadows. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Biotic dispersal in eelgrass Zostera marina.\n \n \n \n\n\n \n Sumoski, S. E.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{sumoski_biotic_2012,\n\ttitle = {Biotic dispersal in eelgrass {Zostera} marina},\n\tdoi = {10.3354/meps10145},\n\tabstract = {Dispersal is a critical process in the life history of nearly all plant species and can be facilitated by both abiotic and biotic mechanisms. Despite an abundance of vertebrate fauna utilizing seagrass meadows as a feeding area and thus capable of consuming and excreting seeds, little work has been conducted on biotic seed dispersal mechanisms. The objectives of this study were to (1) determine whether seeds of the seagrass Zostera marina could pass through the digestive systems of resident and transient vertebrates of a seagrass bed and remain viable and (2) determine seed retention times in the guts of each species to estimate dispersal distances of Z. marina seeds by vertebrate dispersers. Excretion and germination rates of consumed seeds for 3 fish species (Fundulus heteroclitus, Sphoeroides maculatus, Lagodon rhomboides), 1 turtle species (Malaclemys terrapin) and 1 waterfowl species (Aythya affinis) showed Z. marina seeds could survive passage through species' digestive systems and successfully germinate. Excretion rates were generally highest for F. heteroclitus, S. maculatus, and M. terrapin, lowest for A. affinis, and moderate for L. rhomboides. Analyses suggest seeds were significantly affected by species' digestive tracts. Maximum dispersal distances are estimated to be 200, 60, 1500, and 19 500 m for F. heteroclitus, L. rhomboides, M. terrapin, and A. affinis, respectively. Data here provide strong evidence that biotic dispersal can occur in Z. marina, and biotically transported seeds can be dispersed to isolated areas unlikely to receive seeds via abiotic mechanisms. Biotic dispersal may rival or exceed abiotic mechanisms. Future seagrass dispersal models should incorporate biotic dispersal as a seed transport mechanism. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Sumoski, Sarah E. and Orth, Robert J.},\n\tyear = {2012},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Dispersal is a critical process in the life history of nearly all plant species and can be facilitated by both abiotic and biotic mechanisms. Despite an abundance of vertebrate fauna utilizing seagrass meadows as a feeding area and thus capable of consuming and excreting seeds, little work has been conducted on biotic seed dispersal mechanisms. The objectives of this study were to (1) determine whether seeds of the seagrass Zostera marina could pass through the digestive systems of resident and transient vertebrates of a seagrass bed and remain viable and (2) determine seed retention times in the guts of each species to estimate dispersal distances of Z. marina seeds by vertebrate dispersers. Excretion and germination rates of consumed seeds for 3 fish species (Fundulus heteroclitus, Sphoeroides maculatus, Lagodon rhomboides), 1 turtle species (Malaclemys terrapin) and 1 waterfowl species (Aythya affinis) showed Z. marina seeds could survive passage through species' digestive systems and successfully germinate. Excretion rates were generally highest for F. heteroclitus, S. maculatus, and M. terrapin, lowest for A. affinis, and moderate for L. rhomboides. Analyses suggest seeds were significantly affected by species' digestive tracts. Maximum dispersal distances are estimated to be 200, 60, 1500, and 19 500 m for F. heteroclitus, L. rhomboides, M. terrapin, and A. affinis, respectively. Data here provide strong evidence that biotic dispersal can occur in Z. marina, and biotically transported seeds can be dispersed to isolated areas unlikely to receive seeds via abiotic mechanisms. Biotic dispersal may rival or exceed abiotic mechanisms. Future seagrass dispersal models should incorporate biotic dispersal as a seed transport mechanism. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Characterization and ecological implication of eelgrass life history strategies near the species' southern limit in the western North Atlantic.\n \n \n \n\n\n \n Jarvis, J. C.; Moore, K. A.; and Kenworthy, W. J.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2012.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{jarvis_characterization_2012,\n\ttitle = {Characterization and ecological implication of eelgrass life history strategies near the species' southern limit in the western {North} {Atlantic}},\n\tdoi = {10.3354/meps09428},\n\tabstract = {Eelgrass Zostera marina L. populations located near the species southern limit in the western North Atlantic were assessed monthly from July 2007 through November 2008. We identified (1) dominant life history strategies and local environmental conditions in southern Z. marina populations, (2) quantified differences in reproductive phenology between populations and different local environmental conditions, and (3) compared reproductive strategies to established annual and perennial life history paradigms. Observed populations expressed both life history strategies with one Z. marina population completely losing aboveground biomass and reestablishing from seeds (annual model) while another population retained aboveground biomass throughout the year (perennial model). A third life history strategy, characterized here as a mixed-annual population, was also observed after some seedlings were found to reproduce both sexually and asexually during their first year of growth thereby not conforming to any currently established life history paradigm. Development of multiple life history strategies within this region may be in response to stressful summer water temperatures associated with the southern edge of the species' range. We suggest that neither annual nor perennial life history strategies always provide a superior mechanism for population persistence as perennial populations can be susceptible to multiple consecutive years of stress, and annual populations are unable to fully exploit available resources throughout much of the year. The mixed-annual strategy observed here represents another possible life history model which may provide the mechanism necessary for Z. marina populations to persist during times of environmental transition. © Inter-Research 2012.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Jarvis, Jessie C. and Moore, Kenneth A. and Kenworthy, W. Judson},\n\tyear = {2012},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Eelgrass Zostera marina L. populations located near the species southern limit in the western North Atlantic were assessed monthly from July 2007 through November 2008. We identified (1) dominant life history strategies and local environmental conditions in southern Z. marina populations, (2) quantified differences in reproductive phenology between populations and different local environmental conditions, and (3) compared reproductive strategies to established annual and perennial life history paradigms. Observed populations expressed both life history strategies with one Z. marina population completely losing aboveground biomass and reestablishing from seeds (annual model) while another population retained aboveground biomass throughout the year (perennial model). A third life history strategy, characterized here as a mixed-annual population, was also observed after some seedlings were found to reproduce both sexually and asexually during their first year of growth thereby not conforming to any currently established life history paradigm. Development of multiple life history strategies within this region may be in response to stressful summer water temperatures associated with the southern edge of the species' range. We suggest that neither annual nor perennial life history strategies always provide a superior mechanism for population persistence as perennial populations can be susceptible to multiple consecutive years of stress, and annual populations are unable to fully exploit available resources throughout much of the year. The mixed-annual strategy observed here represents another possible life history model which may provide the mechanism necessary for Z. marina populations to persist during times of environmental transition. © Inter-Research 2012.\n
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\n \n\n \n \n \n \n \n Influence of environmental factors on Vallisneria americana seed germination.\n \n \n \n\n\n \n Jarvis, J. C.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{jarvis_influence_2008,\n\ttitle = {Influence of environmental factors on {Vallisneria} americana seed germination},\n\tdoi = {10.1016/j.aquabot.2007.12.001},\n\tabstract = {Over the course of a growing season (April-October) water quality (water temperature, light, salinity, dissolved oxygen) and reproductive phenology (biomass, production of flowering shoots and seed pods, seed bank densities) were quantified in three Vallisneria americana beds in Nanjemoy Creek, MD, a tributary to the Chesapeake Bay. Clonal production of V. americana biomass increased at all sites when water temperatures rose above 25 °C. Flowering occurred during peak biomass (August-September) and resulted in the production of up to 16,000 seeds m-2 at the end of the growing season. However, observed seed bank densities represented {\\textbackslash}textless1\\% of seed production. Laboratory experiments quantified the effects of dissolved oxygen (0.29-8.00 mg l-1), light (0-160 μmol m2 s-1), temperature (13-29 °C), salinity (0.1-17.4 psu), sediment composition (3-86\\% sand; 0.9-8.3\\% sediment organic content), and burial depth (0.2-10 cm) on V. americana seed germination. Germination of V. americana seeds was enhanced (greater overall germination and shorter time to germination) under oxygenated conditions (8.00 mg l-1), temperatures {\\textbackslash}textgreater22 °C, salinities of {\\textbackslash}textless1 psu, and in sediments composed of ≤3\\% organic content and {\\textbackslash}textgreater40\\% sand. Light ({\\textbackslash}textless160 μmol m-2 s-1) and burial depth (0.2-10 cm) had no significant effects on germination. Temperatures most favorable for seed germination ({\\textbackslash}textgreater22 °C) occurred in June, 2 months in the growing season just prior to development of peak vegetative standing stock. Seedlings were therefore at a distinct disadvantage to plants developed from over wintering buds. A lack of viable seed retention and inadequate environmental conditions at critical times in the growing season may be limiting seed germination success and subsequent seedling establishment within V. americana beds in the Chesapeake Bay. However, ungerminated seeds were found to maintain high viability, especially at salinities of 10 psu that can have significant negative effects of shoot growth survival. This suggests that seeds may serve as a source of reproductive material for bed recovery after periods of drought or other stressful conditions in estuarine systems. © 2007 Elsevier B.V. All rights reserved.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Jarvis, Jessie C. and Moore, Kenneth A.},\n\tyear = {2008},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Over the course of a growing season (April-October) water quality (water temperature, light, salinity, dissolved oxygen) and reproductive phenology (biomass, production of flowering shoots and seed pods, seed bank densities) were quantified in three Vallisneria americana beds in Nanjemoy Creek, MD, a tributary to the Chesapeake Bay. Clonal production of V. americana biomass increased at all sites when water temperatures rose above 25 °C. Flowering occurred during peak biomass (August-September) and resulted in the production of up to 16,000 seeds m-2 at the end of the growing season. However, observed seed bank densities represented \\textless1% of seed production. Laboratory experiments quantified the effects of dissolved oxygen (0.29-8.00 mg l-1), light (0-160 μmol m2 s-1), temperature (13-29 °C), salinity (0.1-17.4 psu), sediment composition (3-86% sand; 0.9-8.3% sediment organic content), and burial depth (0.2-10 cm) on V. americana seed germination. Germination of V. americana seeds was enhanced (greater overall germination and shorter time to germination) under oxygenated conditions (8.00 mg l-1), temperatures \\textgreater22 °C, salinities of \\textless1 psu, and in sediments composed of ≤3% organic content and \\textgreater40% sand. Light (\\textless160 μmol m-2 s-1) and burial depth (0.2-10 cm) had no significant effects on germination. Temperatures most favorable for seed germination (\\textgreater22 °C) occurred in June, 2 months in the growing season just prior to development of peak vegetative standing stock. Seedlings were therefore at a distinct disadvantage to plants developed from over wintering buds. A lack of viable seed retention and inadequate environmental conditions at critical times in the growing season may be limiting seed germination success and subsequent seedling establishment within V. americana beds in the Chesapeake Bay. However, ungerminated seeds were found to maintain high viability, especially at salinities of 10 psu that can have significant negative effects of shoot growth survival. This suggests that seeds may serve as a source of reproductive material for bed recovery after periods of drought or other stressful conditions in estuarine systems. © 2007 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Factors influencing reproduction in American wild celery: A synthesis.\n \n \n \n\n\n \n McFarland, D. G.; and Shafer, D. J.\n\n\n \n\n\n\n Journal of Aquatic Plant Management. 2008.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{mcfarland_factors_2008,\n\ttitle = {Factors influencing reproduction in {American} wild celery: {A} synthesis},\n\tabstract = {Dramatic declines in American wild celery (Vallisneria americana Michaux), a native submersed aquatic plant, have been widely reported in the United States since the 1960s, especially from the Midwest to the Northeast. Though methods for restoration are being developed and implemented, progress has been hampered by the need for greater understanding of the species' biological traits and response to environmental change. Here, we review available literature on reproductive ecology of wild celery, focusing on environmental influences on the production and early stages of growth of different propagule types. A background profile of the species describes its ecological importance, field characteristics, taxonomy, life history, and geographical distribution. Critical gaps in present knowledge indicate much has yet to be learned to identify different ecotypes of wild celery based on phenological and genetic distinctions. Further research is also needed to assess potential establishment from seed for consideration as an alternative to (or supplement to) vegetative propagules in restoration strategies.},\n\tjournal = {Journal of Aquatic Plant Management},\n\tauthor = {McFarland, Dwilette G. and Shafer, D. J.},\n\tyear = {2008},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Dramatic declines in American wild celery (Vallisneria americana Michaux), a native submersed aquatic plant, have been widely reported in the United States since the 1960s, especially from the Midwest to the Northeast. Though methods for restoration are being developed and implemented, progress has been hampered by the need for greater understanding of the species' biological traits and response to environmental change. Here, we review available literature on reproductive ecology of wild celery, focusing on environmental influences on the production and early stages of growth of different propagule types. A background profile of the species describes its ecological importance, field characteristics, taxonomy, life history, and geographical distribution. Critical gaps in present knowledge indicate much has yet to be learned to identify different ecotypes of wild celery based on phenological and genetic distinctions. Further research is also needed to assess potential establishment from seed for consideration as an alternative to (or supplement to) vegetative propagules in restoration strategies.\n
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\n \n\n \n \n \n \n \n Using seeds to propagate and restore Vallisneria americana Michaux (Wild Celery) in the Chesapeake Bay.\n \n \n \n\n\n \n Moore, K. A; and Jarvis, J. C\n\n\n \n\n\n\n Technical Report 2007.\n Publication Title: SAV Technical Notes Collection (ERDC/TN SAV-07-3)\n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@techreport{moore_using_2007,\n\ttitle = {Using seeds to propagate and restore {Vallisneria} americana {Michaux} ({Wild} {Celery}) in the {Chesapeake} {Bay}},\n\tabstract = {Figure 1. Vallisneria americana (Michx.) is a dioecious perennial species of submerged aquatic vegetation in Chesapeake Bay. These specimens are transplants grown from planted seeds.},\n\tauthor = {Moore, Kenneth A and Jarvis, Jesse C},\n\tyear = {2007},\n\tnote = {Publication Title: SAV Technical Notes Collection (ERDC/TN SAV-07-3)},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Figure 1. Vallisneria americana (Michx.) is a dioecious perennial species of submerged aquatic vegetation in Chesapeake Bay. These specimens are transplants grown from planted seeds.\n
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\n \n\n \n \n \n \n \n Effects of edge/interior and patch structure on reproduction in Zostera marina L. in Chesapeake Bay, USA.\n \n \n \n\n\n \n Harwell, M. C.; and Rhode, J. M.\n\n\n \n\n\n\n Aquatic Botany. 2007.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{harwell_effects_2007,\n\ttitle = {Effects of edge/interior and patch structure on reproduction in {Zostera} marina {L}. in {Chesapeake} {Bay}, {USA}},\n\tdoi = {10.1016/j.aquabot.2007.04.007},\n\tabstract = {We examined the effects of location (patch edge vs. interior) and shoot density (individual, patchy, continuous) on reproduction in three natural and two transplanted Chesapeake Bay (USA) stands of the submerged marine angiosperm Zostera marina L. (eelgrass; Zosteraceae). There were no edge effects on demographic-based reproductive effort or reproductive output (propagule production), and patch structure (individual, patchy, continuous) alone never accounted for the majority of variability in any metric. Transplant site was the most important predictor of eelgrass reproduction response, and relationships among metrics were predictable within sites. Our results suggest that, in Chesapeake Bay eelgrass, environmental factors acting at a regional scale (km) have a stronger impact on reproductive investment than those at a patch scale (1-10 m). Since tradeoffs between clonal and sexual production are mediated primarily by exogenous environmental factors, site selection may be more critical than transplant configuration for producing self sustaining stands, and achieving long-term restoration success. © 2007 Elsevier B.V. All rights reserved.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Harwell, Matthew C. and Rhode, Jennifer M.},\n\tyear = {2007},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n We examined the effects of location (patch edge vs. interior) and shoot density (individual, patchy, continuous) on reproduction in three natural and two transplanted Chesapeake Bay (USA) stands of the submerged marine angiosperm Zostera marina L. (eelgrass; Zosteraceae). There were no edge effects on demographic-based reproductive effort or reproductive output (propagule production), and patch structure (individual, patchy, continuous) alone never accounted for the majority of variability in any metric. Transplant site was the most important predictor of eelgrass reproduction response, and relationships among metrics were predictable within sites. Our results suggest that, in Chesapeake Bay eelgrass, environmental factors acting at a regional scale (km) have a stronger impact on reproductive investment than those at a patch scale (1-10 m). Since tradeoffs between clonal and sexual production are mediated primarily by exogenous environmental factors, site selection may be more critical than transplant configuration for producing self sustaining stands, and achieving long-term restoration success. © 2007 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Seagrass recovery in the Delmarva Coastal Bays, USA.\n \n \n \n\n\n \n Orth, R. J.; Luckenbach, M. L.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Aquatic Botany. 2006.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_seagrass_2006-1,\n\ttitle = {Seagrass recovery in the {Delmarva} {Coastal} {Bays}, {USA}},\n\tdoi = {10.1016/j.aquabot.2005.07.007},\n\tabstract = {Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319 ha reported through 2003 compared to 2129 ha in 1986, an average expansion rate of 305 ha year -1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4 m 2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2 ha in four coastal bays having no seagrass, totaling approximately 46 ha through 2004. Successful germination (estimated at 5-10\\% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38\\% of the bottom in 52-0.4 ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds. © 2005 Elsevier B.V. All rights reserved.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Luckenbach, Mark L. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tyear = {2006},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319 ha reported through 2003 compared to 2129 ha in 1986, an average expansion rate of 305 ha year -1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4 m 2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2 ha in four coastal bays having no seagrass, totaling approximately 46 ha through 2004. Successful germination (estimated at 5-10% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38% of the bottom in 52-0.4 ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds. © 2005 Elsevier B.V. All rights reserved.\n
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\n \n\n \n \n \n \n \n Seed production from the mixed mating system of Chesapeake Bay (USA) eelgrass (Zostera marina; Zosteraceae).\n \n \n \n\n\n \n Rhode, J. M.; and Duffy, J. E.\n\n\n \n\n\n\n American Journal of Botany. 2004.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{rhode_seed_2004,\n\ttitle = {Seed production from the mixed mating system of {Chesapeake} {Bay} ({USA}) eelgrass ({Zostera} marina; {Zosteraceae})},\n\tdoi = {10.3732/ajb.91.2.192},\n\tabstract = {In monoecious plants, gametes can be exchanged in three ways: among unrelated genets (outbreeding), with close relatives (in-breeding), or within individuals (geitonogamous selfing). These different mating systems may have consequences for population demography and fitness. The experiment presented herein used artificial crosses to examine the mating system of Chesapeake Bay, Virginia, USA eelgrass (Zostera marina L; Zosteraceae), a bisexual submerged aquatic plant that can outbreed, inbreed, and self. Genetic data indicate severe heterozygosity deficiencies and patchy genotype distribution in these beds, suggesting that plants therein reproduce primarily by vegetative propagation, autogamy, or geitonogamy. To clarify eelgrass reproductive strategies, flowers from three genetically and geographically distinct beds were hand-pollinated in outbred, inbred, and selfed matings. Fertilization success and seed production, life history stages which contribute greatly to the numeric maintenance of populations, were monitored. We found no evidence that inbreeding had negative consequences for seed production. On the contrary, selfed matings produced seeds significantly more frequently than outcrossed matings and produced significantly larger numbers of seeds than either inbred or outbred matings. These results contrast with patterns for eelgrass in other regions but might be expected for similar populations in which pollen limitation or a short reproductive season renders selfing advantageous.},\n\tjournal = {American Journal of Botany},\n\tauthor = {Rhode, Jennifer M. and Duffy, J. Emmett},\n\tyear = {2004},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n In monoecious plants, gametes can be exchanged in three ways: among unrelated genets (outbreeding), with close relatives (in-breeding), or within individuals (geitonogamous selfing). These different mating systems may have consequences for population demography and fitness. The experiment presented herein used artificial crosses to examine the mating system of Chesapeake Bay, Virginia, USA eelgrass (Zostera marina L; Zosteraceae), a bisexual submerged aquatic plant that can outbreed, inbreed, and self. Genetic data indicate severe heterozygosity deficiencies and patchy genotype distribution in these beds, suggesting that plants therein reproduce primarily by vegetative propagation, autogamy, or geitonogamy. To clarify eelgrass reproductive strategies, flowers from three genetically and geographically distinct beds were hand-pollinated in outbred, inbred, and selfed matings. Fertilization success and seed production, life history stages which contribute greatly to the numeric maintenance of populations, were monitored. We found no evidence that inbreeding had negative consequences for seed production. On the contrary, selfed matings produced seeds significantly more frequently than outcrossed matings and produced significantly larger numbers of seeds than either inbred or outbred matings. These results contrast with patterns for eelgrass in other regions but might be expected for similar populations in which pollen limitation or a short reproductive season renders selfing advantageous.\n
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\n \n\n \n \n \n \n \n Seed-density effects on germination and initial seedling establishment in eelgrass Zostera marina in the Chesapeake Bay region.\n \n \n \n\n\n \n Orth, R. J.; Fishman, J. R.; Harwell, M. C.; and Marion, S. R.\n\n\n \n\n\n\n Marine Ecology Progress Series. 2003.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_seed-density_2003,\n\ttitle = {Seed-density effects on germination and initial seedling establishment in eelgrass {Zostera} marina in the {Chesapeake} {Bay} region},\n\tdoi = {10.3354/meps250071},\n\tabstract = {The influence of Zostera marina L. seed-density on germination and initial seedling success was investigated using seed-addition field experiments at 2 scales in the Chesapeake Bay region in 1999 and 2000. We first tested whether germination rates and initial seedling establishment were affected by initial seed-densities of 2.5, 25, 250, and 1250 seeds m-2 within 4 m2 plots. We then tested whether plot size affects germination rates, following the hypothesis that rates of seed predation might be different in large and small plots. We broadcast seeds at a single density (500 seeds m-2) but at a much larger plot size (100 m2, or 25 times the size of the small plots). In the spring following seed broadcast, seedlings were present in most 4 m2 plots (seedling densities of 0.6 to 15.4\\% of the number of seeds released in 1999, and 3.3 to 23.3\\% of those released in 2000) and in all 100 m2 plots (4.3\\% to 13.9\\%). Seed-density effects were not significant in 1999 or 2000, while site effects were significant in both years. The percentages of seedlings in the larger plots were similar to those in the smaller plots. These results suggest that there were no density-dependent effects on germination and initial seedling establishment, and that within the size range of plots examined in this study, such processes are not likely to be scale-dependent. The significant differences among the sites may be related to micro-topographic complexities of the bottom caused by both biotic and abiotic factors that allow seeds to be retained close to where they settle. Our data, combined with previously published data on seed dispersal and patch dynamics, stress the importance of conserving existing beds, regardless of bed size and shoot density, since these are sources of seeds that may establish new patches. The data may also help in developing strategies for the restoration of denuded sites using seeds instead of adult plants.},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and Fishman, James R. and Harwell, Matthew C. and Marion, Scott R.},\n\tyear = {2003},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n The influence of Zostera marina L. seed-density on germination and initial seedling success was investigated using seed-addition field experiments at 2 scales in the Chesapeake Bay region in 1999 and 2000. We first tested whether germination rates and initial seedling establishment were affected by initial seed-densities of 2.5, 25, 250, and 1250 seeds m-2 within 4 m2 plots. We then tested whether plot size affects germination rates, following the hypothesis that rates of seed predation might be different in large and small plots. We broadcast seeds at a single density (500 seeds m-2) but at a much larger plot size (100 m2, or 25 times the size of the small plots). In the spring following seed broadcast, seedlings were present in most 4 m2 plots (seedling densities of 0.6 to 15.4% of the number of seeds released in 1999, and 3.3 to 23.3% of those released in 2000) and in all 100 m2 plots (4.3% to 13.9%). Seed-density effects were not significant in 1999 or 2000, while site effects were significant in both years. The percentages of seedlings in the larger plots were similar to those in the smaller plots. These results suggest that there were no density-dependent effects on germination and initial seedling establishment, and that within the size range of plots examined in this study, such processes are not likely to be scale-dependent. The significant differences among the sites may be related to micro-topographic complexities of the bottom caused by both biotic and abiotic factors that allow seeds to be retained close to where they settle. Our data, combined with previously published data on seed dispersal and patch dynamics, stress the importance of conserving existing beds, regardless of bed size and shoot density, since these are sources of seeds that may establish new patches. The data may also help in developing strategies for the restoration of denuded sites using seeds instead of adult plants.\n
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\n \n\n \n \n \n \n \n Seed bank patterns in Chesapeake Bay eelgrass (Zostera marina L.): A bay-wide perspective.\n \n \n \n\n\n \n Harwell, M. C.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{harwell_seed_2002,\n\ttitle = {Seed bank patterns in {Chesapeake} {Bay} eelgrass ({Zostera} marina {L}.): {A} bay-wide perspective},\n\tdoi = {10.1007/BF02692216},\n\tabstract = {The decline of eelgrass (Zostera marina) in Chesapeake Bay in the 1960s and 1970s has been studied in the context of changes in water quality and habitat suitability; little effort has focused on the importance of reproductive ecology in understanding current and potential recovery of these populations. The spatial variability of seed-bank characteristics of Z. marina in Chesapeake Bay was explored by a reproductive shoot and seed-bank sampling effort. Seed banks were sampled from 105 beds of submerged aquatic vegetation among 12 zones throughout the lower and middle Chesapeake Bay. Number of viable seeds was highly variable among and within zones, with seeds found in all but one zone and also found in cores not containing any Z. marina shoots. Number of reproductive shoots was also highly variable among and within zones, with differences probably driven by different local environmental conditions. Bay-wide, viable seeds were found in more monospecific Z. marina cores than in mixed species or monospecific Ruppia maritima cores suggesting local biological and environmental control on sexual reproduction. Lower densities of viable seeds in the middle Chesapeake Bay region reflect the lower abundance of Z. marina in these regions and provide context for discussion of historical changes in Z. marina in Chesapeake Bay. While this study focused on a snap shot of the seed bank immediately after establishment, we highlight critical questions for future study that may be important for their conservation and restoration.},\n\tjournal = {Estuaries},\n\tauthor = {Harwell, Matthew C. and Orth, Robert J.},\n\tyear = {2002},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n The decline of eelgrass (Zostera marina) in Chesapeake Bay in the 1960s and 1970s has been studied in the context of changes in water quality and habitat suitability; little effort has focused on the importance of reproductive ecology in understanding current and potential recovery of these populations. The spatial variability of seed-bank characteristics of Z. marina in Chesapeake Bay was explored by a reproductive shoot and seed-bank sampling effort. Seed banks were sampled from 105 beds of submerged aquatic vegetation among 12 zones throughout the lower and middle Chesapeake Bay. Number of viable seeds was highly variable among and within zones, with seeds found in all but one zone and also found in cores not containing any Z. marina shoots. Number of reproductive shoots was also highly variable among and within zones, with differences probably driven by different local environmental conditions. Bay-wide, viable seeds were found in more monospecific Z. marina cores than in mixed species or monospecific Ruppia maritima cores suggesting local biological and environmental control on sexual reproduction. Lower densities of viable seeds in the middle Chesapeake Bay region reflect the lower abundance of Z. marina in these regions and provide context for discussion of historical changes in Z. marina in Chesapeake Bay. While this study focused on a snap shot of the seed bank immediately after establishment, we highlight critical questions for future study that may be important for their conservation and restoration.\n
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\n \n\n \n \n \n \n \n Long-distance dispersal potential in a marine macrophyte.\n \n \n \n\n\n \n Harwell, M. C.; and Orth, R. J.\n\n\n \n\n\n\n Ecology. 2002.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{harwell_long-distance_2002-1,\n\ttitle = {Long-distance dispersal potential in a marine macrophyte},\n\tdoi = {10.1890/0012-9658(2002)083[3319:LDDPIA]2.0.CO;2},\n\tabstract = {Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.},\n\tjournal = {Ecology},\n\tauthor = {Harwell, Matthew C. and Orth, Robert J.},\n\tyear = {2002},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.\n
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\n \n\n \n \n \n \n \n Investigations of the availability and survival of submersed aquatic vegetation propagules in the tidal Potomac River.\n \n \n \n\n\n \n Rybicki, N. B.; McFarland, D. G.; Ruhl, H. A.; Reel, J. T.; and Barko, J. W.\n\n\n \n\n\n\n Estuaries. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{rybicki_investigations_2001,\n\ttitle = {Investigations of the availability and survival of submersed aquatic vegetation propagules in the tidal {Potomac} {River}},\n\tdoi = {10.2307/1353242},\n\tabstract = {The establishment of submersed aquatic vegetation (SAV) at unvegetated sites in the freshwater tidal Potomac River was limited primarily by factors other than propagule availability. For two years, traps were used to quantify the amount of plant material reaching three unvegetated sites over the growing season. The calculated flux values provided a gross estimate of the flux of propagules that could potentially survive if other site factors were suitable. The mean flux of Hydrilla verticillata and all other species (≥ 0.01 gdw m-2 d-1) appeared sufficient to favor the establishment of vegetation, particularly considering the high viability (70-100\\%) of whole plants and fragments under controlled conditions. However, median water clarity values (i.e., for light attenuation, Secchi depth, total suspended solids, and chlorophyll a) were below SAV restoration goals at all unvegetated sites. Additionally, sediments from unvegetated sites showed a potential for nitrogen limitation of the growth of H. verticillata. Our findings support the hypothesis that in the tidal Potomac River, water clarity and nutrient (especially nitrogen) levels in sediment are key to plant community establishment.},\n\tjournal = {Estuaries},\n\tauthor = {Rybicki, N. B. and McFarland, D. G. and Ruhl, H. A. and Reel, J. T. and Barko, J. W.},\n\tyear = {2001},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n The establishment of submersed aquatic vegetation (SAV) at unvegetated sites in the freshwater tidal Potomac River was limited primarily by factors other than propagule availability. For two years, traps were used to quantify the amount of plant material reaching three unvegetated sites over the growing season. The calculated flux values provided a gross estimate of the flux of propagules that could potentially survive if other site factors were suitable. The mean flux of Hydrilla verticillata and all other species (≥ 0.01 gdw m-2 d-1) appeared sufficient to favor the establishment of vegetation, particularly considering the high viability (70-100%) of whole plants and fragments under controlled conditions. However, median water clarity values (i.e., for light attenuation, Secchi depth, total suspended solids, and chlorophyll a) were below SAV restoration goals at all unvegetated sites. Additionally, sediments from unvegetated sites showed a potential for nitrogen limitation of the growth of H. verticillata. Our findings support the hypothesis that in the tidal Potomac River, water clarity and nutrient (especially nitrogen) levels in sediment are key to plant community establishment.\n
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\n \n\n \n \n \n \n \n Influence of a tube-dwelling polychaete on the dispersal of fragmented reproductive shoots of eelgrass.\n \n \n \n\n\n \n Parmee, I.; Cvetkovic, D.; Bonham, C.; and Packham, I.\n\n\n \n\n\n\n Aquatic Botany. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{parmee_influence_2001,\n\ttitle = {Influence of a tube-dwelling polychaete on the dispersal of fragmented reproductive shoots of eelgrass},\n\tdoi = {10.1016/S0304-3770(00)00147-9},\n\tabstract = {Diopatra cuprea (Bosc), a common tube-building polychaete, attaches materials such as algae and shell into the wall of its tube cap, in part, to provide a substrate for potential food resources. Reproductive shoots of eelgrass (Zostera marina L.) break off during seed maturation and can be transported by water movement. As these shoots deteriorate, they become neutrally or negatively buoyant and can be transported along the bottom while still carrying seeds. Analysis of 55 l m2 plots along a 100 m transect in the offshore fringe of an eelgrass bed in the York River, Chesapeake Bay, USA, showed that 70\\% of D. cuprea had fragmented reproductive shoots built into their tube cap walls, with a highly significant regression of shoot to tube density (r2 = 0.76). There was a positive correlation between seedlings and tube caps (r2 = 0.39). D. cuprea may alter hydrodynamics, arresting transport of fragmented reproductive shoots, thereby potentially influencing patch and bed dynamics in both near and distant regions from existing beds. © 2001 Elsevier Science B.V.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Parmee, I. and Cvetkovic, D. and Bonham, C. and Packham, I.},\n\tyear = {2001},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Diopatra cuprea (Bosc), a common tube-building polychaete, attaches materials such as algae and shell into the wall of its tube cap, in part, to provide a substrate for potential food resources. Reproductive shoots of eelgrass (Zostera marina L.) break off during seed maturation and can be transported by water movement. As these shoots deteriorate, they become neutrally or negatively buoyant and can be transported along the bottom while still carrying seeds. Analysis of 55 l m2 plots along a 100 m transect in the offshore fringe of an eelgrass bed in the York River, Chesapeake Bay, USA, showed that 70% of D. cuprea had fragmented reproductive shoots built into their tube cap walls, with a highly significant regression of shoot to tube density (r2 = 0.76). There was a positive correlation between seedlings and tube caps (r2 = 0.39). D. cuprea may alter hydrodynamics, arresting transport of fragmented reproductive shoots, thereby potentially influencing patch and bed dynamics in both near and distant regions from existing beds. © 2001 Elsevier Science B.V.\n
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\n \n\n \n \n \n \n \n Biomechanical properties of the reproductive shoots of eelgrass.\n \n \n \n\n\n \n Patterson, M. R.; Harwell, M. C.; Orth, L. M.; and Orth, R. J.\n\n\n \n\n\n\n Aquatic Botany. 2001.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{patterson_biomechanical_2001,\n\ttitle = {Biomechanical properties of the reproductive shoots of eelgrass},\n\tdoi = {10.1016/S0304-3770(00)00133-9},\n\tabstract = {The biomechanical properties of freshly collected eelgrass (Zostera marina L.) reproductive shoots from a site in the mesohaline region of the Chesapeake Bay during the period of seed release were investigated using a tensometer. Internodal segments closest to, and farthest away from the substrate were loaded in tension until they broke. Breaking stress (strength), breaking strain, toughness, and elastic modulus were calculated from the tensometer data and measurements of the final broken cross-sectional area of each internodal segment. Paired sample tests for individual shoots of the internodal segments closest to and farthest away from the substrate indicated no difference in material properties or cross-sectional area at the location of the break; however, internodal segment length was significantly longer (10\\%) further away from the substrate, and there is a trend of higher values (25-50\\% higher) for all mechanical attributes. Breaking stress, elastic modulus, and toughness, were not normally distributed, but significantly follow a Weibull distribution, while internodal segment length, shoot length, and breaking force were normally distributed. There was no relationship between strength and elastic modulus, but toughness was significantly correlated with strength, meaning strong reproductive shoots can also absorb large strain energies imparted by the environment before breaking. Mean strength, toughness, and elastic modulus are similar to other plants for which these data exist, including macroalgae. The finding of Weibull distributions in biomechanical attributes of the field population indicates that a few strong tough reproductive shoots are always present to resist extreme events, that might otherwise dislodge an entire population. © 2001 Elsevier Science B.V.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Patterson, Mark R. and Harwell, Matthew C. and Orth, Leanna M. and Orth, Robert J.},\n\tyear = {2001},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n The biomechanical properties of freshly collected eelgrass (Zostera marina L.) reproductive shoots from a site in the mesohaline region of the Chesapeake Bay during the period of seed release were investigated using a tensometer. Internodal segments closest to, and farthest away from the substrate were loaded in tension until they broke. Breaking stress (strength), breaking strain, toughness, and elastic modulus were calculated from the tensometer data and measurements of the final broken cross-sectional area of each internodal segment. Paired sample tests for individual shoots of the internodal segments closest to and farthest away from the substrate indicated no difference in material properties or cross-sectional area at the location of the break; however, internodal segment length was significantly longer (10%) further away from the substrate, and there is a trend of higher values (25-50% higher) for all mechanical attributes. Breaking stress, elastic modulus, and toughness, were not normally distributed, but significantly follow a Weibull distribution, while internodal segment length, shoot length, and breaking force were normally distributed. There was no relationship between strength and elastic modulus, but toughness was significantly correlated with strength, meaning strong reproductive shoots can also absorb large strain energies imparted by the environment before breaking. Mean strength, toughness, and elastic modulus are similar to other plants for which these data exist, including macroalgae. The finding of Weibull distributions in biomechanical attributes of the field population indicates that a few strong tough reproductive shoots are always present to resist extreme events, that might otherwise dislodge an entire population. © 2001 Elsevier Science B.V.\n
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\n \n\n \n \n \n \n \n A review of issues in seagrass seed dormancy and germination: Implications for conservation and restoration.\n \n \n \n\n\n \n Orth, R. J.; Harwell, M. C.; Bailey, E. M.; Bartholomew, A.; Jawad, J. T.; Lombana, A. V.; Moore, K. A.; Rhode, J. M.; and Woods, H. E.\n\n\n \n\n\n\n 2000.\n Publication Title: Marine Ecology Progress Series\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@book{orth_review_2000,\n\ttitle = {A review of issues in seagrass seed dormancy and germination: {Implications} for conservation and restoration},\n\tabstract = {Seagrasses have received considerable attention over the past 2 decades because of the multiple ecological roles they play in estuarine and coastal ecosystems and concerns over worldwide losses of seagrass habitat due to direct and indirect human impacts. Restoration and conservation efforts are underway in some areas of the world, but progress may be limited by the paucity of information on the role of seeds in bed dynamics. Although flowering occurs in most of the 58 seagrass species, seed germination data exist for only 19 of the 42 species that have some period of dormancy, with only 93 published references to field and/or laboratory studies. This review addresses critical issues in conservation and restoration of seagrasses involving seed dormancy (e.g. environmental vs physiological), existence and type of seed bank (transient or persistent), and factors influencing seed germination (e.g. salinity, temperature, light). Results of many earlier published studies relating seed germination to various environmental factors may need re-examination given more recent published data which show a confounding influence of oxygen level on the germination process. We highlight the importance of conducting ecologically meaningful germination studies, including germination experiments conducted in sediments. We also identify questions for future research that may figure prominently in landscape level questions regarding protected marine or estuarine reserves, habitat fragmentation, and restoration.},\n\tauthor = {Orth, Robert J. and Harwell, Matthew C. and Bailey, Eva M. and Bartholomew, Aaron and Jawad, Jennifer T. and Lombana, Alfonso V. and Moore, Kenneth A. and Rhode, Jennifer M. and Woods, Helen E.},\n\tyear = {2000},\n\tdoi = {10.3354/meps200277},\n\tnote = {Publication Title: Marine Ecology Progress Series},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Seagrasses have received considerable attention over the past 2 decades because of the multiple ecological roles they play in estuarine and coastal ecosystems and concerns over worldwide losses of seagrass habitat due to direct and indirect human impacts. Restoration and conservation efforts are underway in some areas of the world, but progress may be limited by the paucity of information on the role of seeds in bed dynamics. Although flowering occurs in most of the 58 seagrass species, seed germination data exist for only 19 of the 42 species that have some period of dormancy, with only 93 published references to field and/or laboratory studies. This review addresses critical issues in conservation and restoration of seagrasses involving seed dormancy (e.g. environmental vs physiological), existence and type of seed bank (transient or persistent), and factors influencing seed germination (e.g. salinity, temperature, light). Results of many earlier published studies relating seed germination to various environmental factors may need re-examination given more recent published data which show a confounding influence of oxygen level on the germination process. We highlight the importance of conducting ecologically meaningful germination studies, including germination experiments conducted in sediments. We also identify questions for future research that may figure prominently in landscape level questions regarding protected marine or estuarine reserves, habitat fragmentation, and restoration.\n
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\n \n\n \n \n \n \n \n Effects of a deposit-feeding invertebrate on the entrapment of Zostera marina L. seeds.\n \n \n \n\n\n \n Luckenbach, M. W.; and Orth, R. J.\n\n\n \n\n\n\n Aquatic Botany. 1999.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{luckenbach_effects_1999,\n\ttitle = {Effects of a deposit-feeding invertebrate on the entrapment of {Zostera} marina {L}. seeds},\n\tdoi = {10.1016/S0304-3770(98)00098-9},\n\tabstract = {Eelgrass, Zostera marina, relies upon seed dispersal for colonization of new habitats. The seeds are not readily transported in suspension; however, they have low erosion thresholds and are subject to horizontal transport as bedload at relatively low bottom shear stress. Field germination patterns suggest that seeds rarely travel far from the point of release and quickly become buried in the sediment, even in habitats where boundary-layer flows exceed those necessary to erode seeds. In many sedimentary habitats it is likely that the activities of benthic and demersal organisms will affect the horizontal movement and burial of seeds, thus providing an explanation for the patterns of seedling establishment in previously reported experiments. We investigated the effects of a common animal in estuarine sediments on the entrapment of Z. marina seeds. In a series of flume experiments we manipulated the densities of the subsurface deposit-feeding polychaete Clymenella torquata (Low: 96 worms m-2; Medium: 192 worms m-2; High: 288 worms m-2) and related trapping of seeds to worm density and bioturbation rates. The results suggest that modifications to the sediment surface (i.e. topographic relief) resulting from feeding and defecation activities of subsurface deposit feeders can act to trap seeds. Seeds were trapped in the medium and high density worm treatments in greater numbers than in the low density and no worm treatments. Our findings indicate that benthic invertebrates, through their modification of sediments may affect the horizontal (bedload) and, hence, vertical (burial) transport of Z. marina seeds.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Luckenbach, Mark W. and Orth, Robert J.},\n\tyear = {1999},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Eelgrass, Zostera marina, relies upon seed dispersal for colonization of new habitats. The seeds are not readily transported in suspension; however, they have low erosion thresholds and are subject to horizontal transport as bedload at relatively low bottom shear stress. Field germination patterns suggest that seeds rarely travel far from the point of release and quickly become buried in the sediment, even in habitats where boundary-layer flows exceed those necessary to erode seeds. In many sedimentary habitats it is likely that the activities of benthic and demersal organisms will affect the horizontal movement and burial of seeds, thus providing an explanation for the patterns of seedling establishment in previously reported experiments. We investigated the effects of a common animal in estuarine sediments on the entrapment of Z. marina seeds. In a series of flume experiments we manipulated the densities of the subsurface deposit-feeding polychaete Clymenella torquata (Low: 96 worms m-2; Medium: 192 worms m-2; High: 288 worms m-2) and related trapping of seeds to worm density and bioturbation rates. The results suggest that modifications to the sediment surface (i.e. topographic relief) resulting from feeding and defecation activities of subsurface deposit feeders can act to trap seeds. Seeds were trapped in the medium and high density worm treatments in greater numbers than in the low density and no worm treatments. Our findings indicate that benthic invertebrates, through their modification of sediments may affect the horizontal (bedload) and, hence, vertical (burial) transport of Z. marina seeds.\n
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\n \n\n \n \n \n \n \n Genetic diversity and structure of natural and transplanted eelgrass populations in the Chesapeake and Chincoteague bays.\n \n \n \n\n\n \n Williams, S. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries. 1998.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{williams_genetic_1998,\n\ttitle = {Genetic diversity and structure of natural and transplanted eelgrass populations in the {Chesapeake} and {Chincoteague} bays},\n\tdoi = {10.2307/1352551},\n\tabstract = {The objective of this study was to gain baseline population data on the genetic diversity and differentiation of eelgrass (Zostera marina L.) populations in the Chesapeake and Chincoteague bays. Natural and transplanted eelgrass beds were compared using starch gel electrophoresis of allozymes. Transplanted eelgrass beds were not reduced in genetic diversity compared with natural beds. Inbreeding coefficients (F(1S)) indicated that transplanted eelgrass beds had theoretically higher levels of outcrossing than natural beds, suggesting the significance of use of seeds as donor material and of seedling recruitment following transplantation diebacks. Natural populations exhibited very great genetic structure (F(ST) = 0.335), but transplanted beds were genetically similar to the donor bed and each other. Genetic diversity was lowest in Chincoteague Bay, reflecting recent restoration history since the 1930s wasting disease and geographical isolation from other east coast populations. These data provide a basis for developing a management plan for conserving eelgrass genetic diversity in the Chesapeake Bay and for guiding estuary-wide restoration efforts. It will be important to recognize that the natural genetic diversity of eelgrass in the estuary is distributed among various populations and is not well represented by single populations.},\n\tjournal = {Estuaries},\n\tauthor = {Williams, Susan L. and Orth, Robert J.},\n\tyear = {1998},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n The objective of this study was to gain baseline population data on the genetic diversity and differentiation of eelgrass (Zostera marina L.) populations in the Chesapeake and Chincoteague bays. Natural and transplanted eelgrass beds were compared using starch gel electrophoresis of allozymes. Transplanted eelgrass beds were not reduced in genetic diversity compared with natural beds. Inbreeding coefficients (F(1S)) indicated that transplanted eelgrass beds had theoretically higher levels of outcrossing than natural beds, suggesting the significance of use of seeds as donor material and of seedling recruitment following transplantation diebacks. Natural populations exhibited very great genetic structure (F(ST) = 0.335), but transplanted beds were genetically similar to the donor bed and each other. Genetic diversity was lowest in Chincoteague Bay, reflecting recent restoration history since the 1930s wasting disease and geographical isolation from other east coast populations. These data provide a basis for developing a management plan for conserving eelgrass genetic diversity in the Chesapeake Bay and for guiding estuary-wide restoration efforts. It will be important to recognize that the natural genetic diversity of eelgrass in the estuary is distributed among various populations and is not well represented by single populations.\n
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\n \n\n \n \n \n \n \n Effects of predation on Zostera marina L. seed abundance.\n \n \n \n\n\n \n Fishman, J. R.; and Orth, R. J.\n\n\n \n\n\n\n Journal of Experimental Marine Biology and Ecology. 1996.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{fishman_effects_1996,\n\ttitle = {Effects of predation on {Zostera} marina {L}. seed abundance},\n\tdoi = {10.1016/0022-0981(95)00176-X},\n\tabstract = {Predator effects on Zostera marina L. seed abundance were studied in the York River, VA, USA, using enclosure and exclosure caging experiments. Seeds were placed in cages in two concurrent experiments. The first experiment was a predator exclosure experiment to test the effects of excluding predators, using a full predator exclosure cage, a partial exclosure top-only cage, a partial exclosure side only cage and uncaged plots. The second experiment was a predator enclosure experiment, using two highly abundant macro-benthic predators in the Chesapeake Bay: the decapod crustacean Callinectes sapidus Rathbun and the sciaenid fish Micropogonias undulatus L. Additionally, two-week long trials of sequentially protected and exposed seeds were also performed. Replicate treatment plots were sampled by removing the top 5-10 cm of the sediment surface with a suction sampler and still viable seeds in each plot were counted. Full exclosure cages contained significantly higher numbers of seeds than the uncaged or partial caged treatments. Seed abundances in the C. sapidus enclosure cages were significantly less than the full exclusion cage, but not significantly different than the uncaged treatments. Seed abundances in the M. undulatus cages were not significantly different than the full exclusion cage. The least number of seeds were found in the uncaged and partial cage treatments. Results of the sequentially protected and exposed trials were similar to results from the one-week uncaged treatments. These experiments suggest that seed predation can affect the abundance of Z. marina seeds, possibly causing up to 65\\% of the seed losses observed in these experiments. Results suggest that seed predation has the potential to be an important force governing the sexual reproductive success and propagation of eelgrass beds and that the degree of seed loss via predation may be related to predator and primary food abundances.},\n\tjournal = {Journal of Experimental Marine Biology and Ecology},\n\tauthor = {Fishman, James R. and Orth, Robert J.},\n\tyear = {1996},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n Predator effects on Zostera marina L. seed abundance were studied in the York River, VA, USA, using enclosure and exclosure caging experiments. Seeds were placed in cages in two concurrent experiments. The first experiment was a predator exclosure experiment to test the effects of excluding predators, using a full predator exclosure cage, a partial exclosure top-only cage, a partial exclosure side only cage and uncaged plots. The second experiment was a predator enclosure experiment, using two highly abundant macro-benthic predators in the Chesapeake Bay: the decapod crustacean Callinectes sapidus Rathbun and the sciaenid fish Micropogonias undulatus L. Additionally, two-week long trials of sequentially protected and exposed seeds were also performed. Replicate treatment plots were sampled by removing the top 5-10 cm of the sediment surface with a suction sampler and still viable seeds in each plot were counted. Full exclosure cages contained significantly higher numbers of seeds than the uncaged or partial caged treatments. Seed abundances in the C. sapidus enclosure cages were significantly less than the full exclusion cage, but not significantly different than the uncaged treatments. Seed abundances in the M. undulatus cages were not significantly different than the full exclusion cage. The least number of seeds were found in the uncaged and partial cage treatments. Results of the sequentially protected and exposed trials were similar to results from the one-week uncaged treatments. These experiments suggest that seed predation can affect the abundance of Z. marina seeds, possibly causing up to 65% of the seed losses observed in these experiments. Results suggest that seed predation has the potential to be an important force governing the sexual reproductive success and propagation of eelgrass beds and that the degree of seed loss via predation may be related to predator and primary food abundances.\n
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\n \n\n \n \n \n \n \n Seed dispersal in a marine macrophyte: Implications for colonization and restoration.\n \n \n \n\n\n \n Orth, R. J.; Luckenbach, M.; and Moore, K. A.\n\n\n \n\n\n\n Ecology. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_seed_1994,\n\ttitle = {Seed dispersal in a marine macrophyte: {Implications} for colonization and restoration},\n\tdoi = {10.2307/1941597},\n\tjournal = {Ecology},\n\tauthor = {Orth, R. J. and Luckenbach, M. and Moore, K. A.},\n\tyear = {1994},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n \n\n \n \n \n \n \n Environmental regulation of seed germination in Zostera marina L. (eelgrass) in Chesapeake Bay: effects of light, oxygen and sediment burial.\n \n \n \n\n\n \n Moore, K. A.; Orth, R. J.; and Nowak, J. F.\n\n\n \n\n\n\n Aquatic Botany. 1993.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{moore_environmental_1993-1,\n\ttitle = {Environmental regulation of seed germination in {Zostera} marina {L}. (eelgrass) in {Chesapeake} {Bay}: effects of light, oxygen and sediment burial},\n\tdoi = {10.1016/0304-3770(93)90054-Z},\n\tabstract = {The effects of light, oxygen and sediment burial on seed germination of Zostera marina L. were tested in two experiments beginning in 1987 and 1988. In 1987, seeds were placed in flow-through clear plastic tubes or buried at depths of 5, 15 and 25 mm in pots filled with seagrass sediments and held in an outdoor running seawater tank at ambient temperature, salinity and solar irradiance. The seeds began germinating in the sediments when water temperatures dropped to 15°C in mid-October and nearly all were germinated by December. Seeds held in the plastic tubes did not begin to germinate until mid-January. Again in 1988, seeds planted in pots germinated in October when temperatures decreased to 15°C; germination in the oxygenated water column was again delayed throughout the autumn and winter. However, seeds held in the water column in clear vials of deoxygenated water, without sediment, displayed a pattern of rapid fall germination identical to that of the sediment treatments. No consistent effect of light and dark treatments was observed in the water-column seeds. We conclude that eelgrass seeds are well adapted for germination in anoxic conditions and that seed germination in this region is keyed to not only seasonal temperature changes, but also oxygen availability. © 1993.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Moore, Kenneth A. and Orth, Robert J. and Nowak, Judith F.},\n\tyear = {1993},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
\n\n\n
\n The effects of light, oxygen and sediment burial on seed germination of Zostera marina L. were tested in two experiments beginning in 1987 and 1988. In 1987, seeds were placed in flow-through clear plastic tubes or buried at depths of 5, 15 and 25 mm in pots filled with seagrass sediments and held in an outdoor running seawater tank at ambient temperature, salinity and solar irradiance. The seeds began germinating in the sediments when water temperatures dropped to 15°C in mid-October and nearly all were germinated by December. Seeds held in the plastic tubes did not begin to germinate until mid-January. Again in 1988, seeds planted in pots germinated in October when temperatures decreased to 15°C; germination in the oxygenated water column was again delayed throughout the autumn and winter. However, seeds held in the water column in clear vials of deoxygenated water, without sediment, displayed a pattern of rapid fall germination identical to that of the sediment treatments. No consistent effect of light and dark treatments was observed in the water-column seeds. We conclude that eelgrass seeds are well adapted for germination in anoxic conditions and that seed germination in this region is keyed to not only seasonal temperature changes, but also oxygen availability. © 1993.\n
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\n \n\n \n \n \n \n \n Effect of sediment depth and sediment type on the survival of Vallisneria americana Michx grown from tubers.\n \n \n \n\n\n \n Rybicki, N. B.; and Carter, V.\n\n\n \n\n\n\n Aquatic Botany. 1986.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{rybicki_effect_1986,\n\ttitle = {Effect of sediment depth and sediment type on the survival of {Vallisneria} americana {Michx} grown from tubers},\n\tdoi = {10.1016/0304-3770(86)90059-8},\n\tabstract = {Sedimentation resulting from storms may have been one of the reasons for the elimination of submersed aquatic vegetation from the tidal Potomac River in the late 1930's. Laboratory studies were conducted to investigate the effects of different depths of overlying sediment and composition of sediment on the survival of Vallisneria americana Michx (wildcelery) grown from tubers. Survival of plants grown from tubers decreased significantly with increasing sediment depth. Survival of tubers declined from 90\\% or more when buried in 10 cm to no survival in greater than 25 cm of sediment. Survival with depth in sand was significantly lower than in silty clay. Field investigation determined that the majority of tubers in Vallisneria beds are distributed between 10 and 20 cm in depth in silty clay and between 5 and 15 cm in depth in sand. Based on the field distribution of tubers and on the percent survival of plants growing from tubers at each depth in the laboratory experiment, we suggest that the deposition of 10 cm or more of sediment by severe storms such as occurred in the 1930s could contribute to the loss of vegetation in the tidal Potomac River. © 1986.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Rybicki, Nancy B. and Carter, Virginia},\n\tyear = {1986},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Sedimentation resulting from storms may have been one of the reasons for the elimination of submersed aquatic vegetation from the tidal Potomac River in the late 1930's. Laboratory studies were conducted to investigate the effects of different depths of overlying sediment and composition of sediment on the survival of Vallisneria americana Michx (wildcelery) grown from tubers. Survival of plants grown from tubers decreased significantly with increasing sediment depth. Survival of tubers declined from 90% or more when buried in 10 cm to no survival in greater than 25 cm of sediment. Survival with depth in sand was significantly lower than in silty clay. Field investigation determined that the majority of tubers in Vallisneria beds are distributed between 10 and 20 cm in depth in silty clay and between 5 and 15 cm in depth in sand. Based on the field distribution of tubers and on the percent survival of plants growing from tubers at each depth in the laboratory experiment, we suggest that the deposition of 10 cm or more of sediment by severe storms such as occurred in the 1930s could contribute to the loss of vegetation in the tidal Potomac River. © 1986.\n
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\n \n\n \n \n \n \n \n Seed germination and seedling growth of Zostera marina L. (eelgrass) in the chesapeake bay.\n \n \n \n\n\n \n Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{orth_seed_1983,\n\ttitle = {Seed germination and seedling growth of {Zostera} marina {L}. (eelgrass) in the chesapeake bay},\n\tdoi = {10.1016/0304-3770(83)90023-2},\n\tabstract = {Seed germination and seedling growth of Zostera marina L. were monitored in the Chesapeake Bay in 1979 and 1980. Harvested seeds were placed in small acrylic tubes at several sites representing the salinity range of Z. marina distribution. Seed germination was observed first in late September and continued through May, with peaks in the fall and spring. The majority of seeds that germinated (66\\%) did so between December and March when water temperatures ranged from 0-10°C. There was no correlation between sites (different salinity regimes) and frequency of germination rates, indicating that salinity was not a major factor in the germination process in this study. Additional information on seed germination was available for seeds collected in 1977 and 1980 and subsequently monitored for germination at only one site. These data were similar to germination frequency recorded in 1979-1980. Seedling growth was measured from individuals collected from an existing Zostera marina bed. Seedlings were collected from November through May, at which time we could no longer distinguish seedlings from existing vegetative stock. Growth was characterized by the increased length of the primary shoot, number of leaves per shoot and numbers of shoots per plant. Seedling growth was slow during the winter months (water temperature ≤ 10°C) but rapidly increased in the spring (temperatures {\\textbackslash}textgreater 10°C). The size range of the harvested seedlings indicated that seed germination in the field probably occurred from October through April, corroborating evidence from the seed germination experiments. © 1983.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A.},\n\tyear = {1983},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
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\n Seed germination and seedling growth of Zostera marina L. were monitored in the Chesapeake Bay in 1979 and 1980. Harvested seeds were placed in small acrylic tubes at several sites representing the salinity range of Z. marina distribution. Seed germination was observed first in late September and continued through May, with peaks in the fall and spring. The majority of seeds that germinated (66%) did so between December and March when water temperatures ranged from 0-10°C. There was no correlation between sites (different salinity regimes) and frequency of germination rates, indicating that salinity was not a major factor in the germination process in this study. Additional information on seed germination was available for seeds collected in 1977 and 1980 and subsequently monitored for germination at only one site. These data were similar to germination frequency recorded in 1979-1980. Seedling growth was measured from individuals collected from an existing Zostera marina bed. Seedlings were collected from November through May, at which time we could no longer distinguish seedlings from existing vegetative stock. Growth was characterized by the increased length of the primary shoot, number of leaves per shoot and numbers of shoots per plant. Seedling growth was slow during the winter months (water temperature ≤ 10°C) but rapidly increased in the spring (temperatures \\textgreater 10°C). The size range of the harvested seedlings indicated that seed germination in the field probably occurred from October through April, corroborating evidence from the seed germination experiments. © 1983.\n
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\n \n\n \n \n \n \n \n Anthesis and seed production in Zostera marina L. (eelgrass) from the Chesapeake Bay.\n \n \n \n\n\n \n Silberhorn, G. M.; Orth, R. J.; and Moore, K. A.\n\n\n \n\n\n\n Aquatic Botany. 1983.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n \n \n \n \n\n\n\n
\n 
@article{silberhorn_anthesis_1983,\n\ttitle = {Anthesis and seed production in {Zostera} marina {L}. (eelgrass) from the {Chesapeake} {Bay}},\n\tdoi = {10.1016/0304-3770(83)90024-4},\n\tabstract = {Anthesis and seed production in Zostera marina L. were studied in three areas of the Chesapeake Bay from January to June 1980. Inflorescence primordia with distinguishable anthers and pistils were first observed in February when water temperature was 3°C. Development of the reproductive shoots in the field continued after February as water temperature rose, with the first evidence of pollen release in mid-April (water temperature 14.3°C). Stigmata loss was first observed in samples taken in late April at all locations by as water temperatures averaged above 16°C. Pollination was complete at all locations by 19 May and anthers were no longer present. Few reproduction shoots were found on 3-5 June and seed release was assumed to be complete by this time (water temperature 25°C). The density of flowering shoots ranged from 11 to 19\\% of the total number of shoots, producing an estimated 8127 seeds m-2. Comparison of flowering events with other areas along a latitudinal gradient from North Carolina to Canada indicated that reproductive events occurred earlier in the most southern locations and at successively later dates with increasing latitude. © 1983.},\n\tjournal = {Aquatic Botany},\n\tauthor = {Silberhorn, G. M. and Orth, R. J. and Moore, K. A.},\n\tyear = {1983},\n\tkeywords = {Reproductive Biology, Systematics, and Molecular Genetics},\n}\n\n
\n
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\n Anthesis and seed production in Zostera marina L. were studied in three areas of the Chesapeake Bay from January to June 1980. Inflorescence primordia with distinguishable anthers and pistils were first observed in February when water temperature was 3°C. Development of the reproductive shoots in the field continued after February as water temperature rose, with the first evidence of pollen release in mid-April (water temperature 14.3°C). Stigmata loss was first observed in samples taken in late April at all locations by as water temperatures averaged above 16°C. Pollination was complete at all locations by 19 May and anthers were no longer present. Few reproduction shoots were found on 3-5 June and seed release was assumed to be complete by this time (water temperature 25°C). The density of flowering shoots ranged from 11 to 19% of the total number of shoots, producing an estimated 8127 seeds m-2. Comparison of flowering events with other areas along a latitudinal gradient from North Carolina to Canada indicated that reproductive events occurred earlier in the most southern locations and at successively later dates with increasing latitude. © 1983.\n
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\n  \n Restoration and Management\n \n \n (58)\n \n \n
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\n \n\n \n \n \n \n \n \n Assessing Water Quality with Submersed Aquatic Vegetation \\textbar Chesapeake Bay Program.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n Library Catalog: www.chesapeakebay.net\n\n\n\n
\n\n\n\n \n \n \"AssessingPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@misc{noauthor_assessing_nodate,\n\ttitle = {Assessing {Water} {Quality} with {Submersed} {Aquatic} {Vegetation} {\\textbar} {Chesapeake} {Bay} {Program}},\n\turl = {https://www.chesapeakebay.net/what/publications/assessing_water_quality_with_submersed_aquatic_vegetation_habitat_requireme},\n\tabstract = {Submersed aquatic vegetation is comprised of rooted flowering plants that have colonized primarily soft sediment habitats in coastal, esturine, and freshwater habitats. In Chesapeake Bay, seagrasses...},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tnote = {Library Catalog: www.chesapeakebay.net},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n Submersed aquatic vegetation is comprised of rooted flowering plants that have colonized primarily soft sediment habitats in coastal, esturine, and freshwater habitats. In Chesapeake Bay, seagrasses...\n
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\n \n\n \n \n \n \n \n \n (PDF) Habitat Requirements for Submerged Aquatic Vegetation in Chesapeake Bay: Water Quality, Light Regime, and Physical-Chemical Factors.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n \n Library Catalog: www.researchgate.net\n\n\n\n
\n\n\n\n \n \n \"(PDF)Paper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_pdf_nodate,\n\ttitle = {({PDF}) {Habitat} {Requirements} for {Submerged} {Aquatic} {Vegetation} in {Chesapeake} {Bay}: {Water} {Quality}, {Light} {Regime}, and {Physical}-{Chemical} {Factors}},\n\tshorttitle = {({PDF}) {Habitat} {Requirements} for {Submerged} {Aquatic} {Vegetation} in {Chesapeake} {Bay}},\n\turl = {https://www.researchgate.net/publication/225792125_Habitat_Requirements_for_Submerged_Aquatic_Vegetation_in_Chesapeake_Bay_Water_Quality_Light_Regime_and_Physical-Chemical_Factors},\n\tabstract = {PDF {\\textbar} We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where... {\\textbar} Find, read and cite all the research you need on ResearchGate},\n\tlanguage = {en},\n\turldate = {2020-05-15},\n\tjournal = {ResearchGate},\n\tdoi = {http://dx.doi.org/10.1007/BF02803529},\n\tdoi = {http://dx.doi.org/10.1007/BF02803529},\n\tnote = {Library Catalog: www.researchgate.net},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n PDF \\textbar We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where... \\textbar Find, read and cite all the research you need on ResearchGate\n
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\n \n\n \n \n \n \n \n \n (PDF) Production and Field Planting of Vegetative Propagules for Restoration of Redhead Grass and Sago Pondweed in Chesapeake Bay.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n May 2020.\n Library Catalog: www.researchgate.net\n\n\n\n
\n\n\n\n \n \n \"(PDF)Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_pdf_2020-1,\n\ttitle = {({PDF}) {Production} and {Field} {Planting} of {Vegetative} {Propagules} for {Restoration} of {Redhead} {Grass} and {Sago} {Pondweed} in {Chesapeake} {Bay}},\n\turl = {https://www.researchgate.net/publication/235045993_Production_and_Field_Planting_of_Vegetative_Propagules_for_Restoration_of_Redhead_Grass_and_Sago_Pondweed_in_Chesapeake_Bay},\n\tabstract = {PDF {\\textbar} During the last several decades, seagrasses and related submerged aquatic vegetation (SAV) have been lost from shallow waters of Chesapeake Bay... {\\textbar} Find, read and cite all the research you need on ResearchGate},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {ResearchGate},\n\tmonth = may,\n\tyear = {2020},\n\tnote = {Library Catalog: www.researchgate.net},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n PDF \\textbar During the last several decades, seagrasses and related submerged aquatic vegetation (SAV) have been lost from shallow waters of Chesapeake Bay... \\textbar Find, read and cite all the research you need on ResearchGate\n
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\n \n\n \n \n \n \n \n \n Evaluation of a mechanical seed planter for transplanting Zostera marina (eelgrass) seeds \\textbar Request PDF.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n May 2020.\n Library Catalog: www.researchgate.net\n\n\n\n
\n\n\n\n \n \n \"EvaluationPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_evaluation_2020,\n\ttitle = {Evaluation of a mechanical seed planter for transplanting {Zostera} marina (eelgrass) seeds {\\textbar} {Request} {PDF}},\n\turl = {https://www.researchgate.net/publication/242343202_Evaluation_of_a_mechanical_seed_planter_for_transplanting_Zostera_marina_eelgrass_seeds},\n\tabstract = {Request PDF {\\textbar} Evaluation of a mechanical seed planter for transplanting Zostera marina (eelgrass) seeds {\\textbar} Few seagrass transplant projects worldwide have relied on seeds, and those projects using Zostera marina (eelgrass) seeds have generally found low... {\\textbar} Find, read and cite all the research you need on ResearchGate},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {ResearchGate},\n\tmonth = may,\n\tyear = {2020},\n\tdoi = {http://dx.doi.org/10.1016/j.aquabot.2008.07.004},\n\tdoi = {http://dx.doi.org/10.1016/j.aquabot.2008.07.004},\n\tnote = {Library Catalog: www.researchgate.net},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n Request PDF \\textbar Evaluation of a mechanical seed planter for transplanting Zostera marina (eelgrass) seeds \\textbar Few seagrass transplant projects worldwide have relied on seeds, and those projects using Zostera marina (eelgrass) seeds have generally found low... \\textbar Find, read and cite all the research you need on ResearchGate\n
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\n \n\n \n \n \n \n \n \n (PDF) Using Seeds to Propagate and Restore Vallisneria americana Michaux (Wild Celery) in the Chesapeake Bay.\n \n \n \n \n\n\n \n \n\n\n \n\n\n\n May 2020.\n Library Catalog: www.researchgate.net\n\n\n\n
\n\n\n\n \n \n \"(PDF)Paper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@misc{noauthor_pdf_2020,\n\ttitle = {({PDF}) {Using} {Seeds} to {Propagate} and {Restore} {Vallisneria} americana {Michaux} ({Wild} {Celery}) in the {Chesapeake} {Bay}},\n\turl = {https://www.researchgate.net/publication/228877123_Using_Seeds_to_Propagate_and_Restore_Vallisneria_americana_Michaux_Wild_Celery_in_the_Chesapeake_Bay},\n\tabstract = {PDF {\\textbar} PROBLEM: Loss of submerged aquatic vegetation (SAV) has been significant in many coastal and estuarine systems such as the Chesapeake Bay where... {\\textbar} Find, read and cite all the research you need on ResearchGate},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {ResearchGate},\n\tmonth = may,\n\tyear = {2020},\n\tnote = {Library Catalog: www.researchgate.net},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n PDF \\textbar PROBLEM: Loss of submerged aquatic vegetation (SAV) has been significant in many coastal and estuarine systems such as the Chesapeake Bay where... \\textbar Find, read and cite all the research you need on ResearchGate\n
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\n \n\n \n \n \n \n \n Submersed aquatic vegetation in chesapeake bay: Sentinel species in a changing world.\n \n \n \n\n\n \n Orth, R. J.; Dennison, W. C.; Lefcheck, J. S.; Gurbisz, C.; Hannam, M.; Keisman, J.; Landry, J. B.; Moore, K. A.; Murphy, R. R.; Patrick, C. J.; Testa, J.; Weller, D. E.; and Wilcox, D. J.\n\n\n \n\n\n\n 2017.\n Publication Title: BioScience\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n  \n \n 2 downloads\n \n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@book{orth_submersed_2017,\n\ttitle = {Submersed aquatic vegetation in chesapeake bay: {Sentinel} species in a changing world},\n\tabstract = {Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.},\n\tauthor = {Orth, Robert J. and Dennison, William C. and Lefcheck, Jonathan S. and Gurbisz, Cassie and Hannam, Michael and Keisman, Jennifer and Landry, J. Brooke and Moore, Kenneth A. and Murphy, Rebecca R. and Patrick, Christopher J. and Testa, Jeremy and Weller, Donald E. and Wilcox, David J.},\n\tyear = {2017},\n\tdoi = {10.1093/biosci/bix058},\n\tnote = {Publication Title: BioScience},\n\tkeywords = {Restoration and Management},\n}\n\n
\n
\n\n\n
\n Chesapeake Bay has undergone profound changes since European settlement. Increases in human and livestock populations, associated changes in land use, increases in nutrient loadings, shoreline armoring, and depletion of fish stocks have altered the important habitats within the Bay. Submersed aquatic vegetation (SAV) is a critical foundational habitat and provides numerous benefits and services to society. In Chesapeake Bay, SAV species are also indicators of environmental change because of their sensitivity to water quality and shoreline development. As such, S AV has been deeply integrated into regional regulations and annual assessments of management outcomes, restoration efforts, the scientific literature, and popular media coverage. Even so, S AV in Chesapeake Bay faces many historical and emerging challenges. The future of Chesapeake Bay is indicated by and contingent on the success of S AV. Its persistence will require continued action, coupled with new practices, to promote a healthy and sustainable ecosystem.\n
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\n \n\n \n \n \n \n \n \n Boat Propeller Scarring of Seagrass Beds in Lower Chesapeake Bay, USA: Patterns, Causes, Recovery, and Management.\n \n \n \n \n\n\n \n Orth, R. J.; Lefcheck, J. S.; and Wilcox, D. J.\n\n\n \n\n\n\n Estuaries and Coasts, 40(6): 1666–1676. November 2017.\n Number: 6\n\n\n\n
\n\n\n\n \n \n \"BoatPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_boat_2017,\n\ttitle = {Boat {Propeller} {Scarring} of {Seagrass} {Beds} in {Lower} {Chesapeake} {Bay}, {USA}: {Patterns}, {Causes}, {Recovery}, and {Management}},\n\tvolume = {40},\n\tissn = {1559-2731},\n\tshorttitle = {Boat {Propeller} {Scarring} of {Seagrass} {Beds} in {Lower} {Chesapeake} {Bay}, {USA}},\n\turl = {https://doi.org/10.1007/s12237-017-0239-9},\n\tdoi = {10.1007/s12237-017-0239-9},\n\tabstract = {Seagrass beds are subject to numerous anthropogenic influences, including nutrient pollution, shoreline development and modification, and overfishing. Direct human impacts on seagrass though, such as through contact with boat propellers and fishing gear, remains relatively uninvestigated. Here, we use 26 years of aerial imagery and 3 years of ground surveys to explore the degree, distribution, and recovery of scarring in seagrass beds as the result of boat propellers in lower Chesapeake Bay, USA, specifically from commercial haul seine fishing activity. We find that propeller scarring is extensive, particularly on the western shore of the Bay, where pressure from haul seining is more intense. In two areas with the most intense scarring, Browns Bay and Poquoson Flats, annual total length of scars averaged 5575 and 3206 m, respectively. Despite the considerable presence of observable scarring, an individual scar generally persisted for only 2.7 years on average, implying quick recovery, aided by the diverse reproductive habits of the two seagrasses in this region, Zostera marina and Ruppia maritima. Moreover, regulations adopted by the regulary agency responsible for protecting marine habitats in Chesapeake Bay, the Virginia Marine Resources Commission, concerning the timing of haul seining in response to these findings reduced the frequency of new scars 43\\% at Browns Bay and 90\\% at Poquoson Flats since 2003. These results demonstrate that swift and decisive management action, in cooperation with relevant science, can lead to effective conservation of underwater grasses.},\n\tlanguage = {en},\n\tnumber = {6},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Orth, Robert J. and Lefcheck, Jonathan S. and Wilcox, David J.},\n\tmonth = nov,\n\tyear = {2017},\n\tnote = {Number: 6},\n\tkeywords = {Restoration and Management},\n\tpages = {1666--1676},\n}\n\n
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\n Seagrass beds are subject to numerous anthropogenic influences, including nutrient pollution, shoreline development and modification, and overfishing. Direct human impacts on seagrass though, such as through contact with boat propellers and fishing gear, remains relatively uninvestigated. Here, we use 26 years of aerial imagery and 3 years of ground surveys to explore the degree, distribution, and recovery of scarring in seagrass beds as the result of boat propellers in lower Chesapeake Bay, USA, specifically from commercial haul seine fishing activity. We find that propeller scarring is extensive, particularly on the western shore of the Bay, where pressure from haul seining is more intense. In two areas with the most intense scarring, Browns Bay and Poquoson Flats, annual total length of scars averaged 5575 and 3206 m, respectively. Despite the considerable presence of observable scarring, an individual scar generally persisted for only 2.7 years on average, implying quick recovery, aided by the diverse reproductive habits of the two seagrasses in this region, Zostera marina and Ruppia maritima. Moreover, regulations adopted by the regulary agency responsible for protecting marine habitats in Chesapeake Bay, the Virginia Marine Resources Commission, concerning the timing of haul seining in response to these findings reduced the frequency of new scars 43% at Browns Bay and 90% at Poquoson Flats since 2003. These results demonstrate that swift and decisive management action, in cooperation with relevant science, can lead to effective conservation of underwater grasses.\n
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\n \n\n \n \n \n \n \n \n The bay scallop (Argopecten irradians) industry collapse in Virginia and its implications for the successful management of scallop-seagrass habitats.\n \n \n \n \n\n\n \n Oreska, M. P. J.; Truitt, B.; Orth, R. J.; and Luckenbach, M. W.\n\n\n \n\n\n\n Marine Policy, 75: 116–124. January 2017.\n \n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{oreska_bay_2017,\n\ttitle = {The bay scallop ({Argopecten} irradians) industry collapse in {Virginia} and its implications for the successful management of scallop-seagrass habitats},\n\tvolume = {75},\n\tissn = {0308-597X},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0308597X16303529},\n\tdoi = {10.1016/j.marpol.2016.10.021},\n\tabstract = {Virginia supported the most productive bay scallop (Argopecten irradians) fishery in the United States in 1930, but the fishery disappeared three years later and never recovered. This collapse highlights a tipping point, but managers of extant bay scallop fisheries have not looked to this case for guidance, because the collapse has long been attributed to an exogenous eelgrass (Zostera marina) ‘wasting disease’ pandemic. Consequently, it remains little understood. However, efforts to restore the fishery, following successful eelgrass restoration, now warrant a thorough examination of its economic significance and disappearance. This study comprehensively surveyed information on the original fishery and reconstructed the pre-collapse population to evaluate restoration prospects and management strategies that reduce the risk of future scallop-seagrass system collapses. Harvest records suggest that overharvesting possibly contributed to the Virginia fishery disappearance—a factor that influenced other bay scallop fisheries but did not alarm contemporary managers in Virginia. The harvest peaked before managers observed eelgrass disappearing and exceeded most pre-collapse population estimates. Intensive dredging possibly precipitated a feedback that reduced scallop recruitment by lowering seagrass shoot densities. Managers should, therefore, consider a potential tradeoff between future scallop harvest and eelgrass restoration goals. The restored wild scallop population in Virginia cannot yet support a commercial fishery at historic levels, which removed between 270 and 380x as many individuals. However, the economic risks associated with reestablishing this fishery are low. The collapse did not cause a significant loss in total economic value, because harvesters rapidly shifted focus to clams, supplanting lost scallop revenue.},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {Marine Policy},\n\tauthor = {Oreska, Matthew P. J. and Truitt, Barry and Orth, Robert J. and Luckenbach, Mark W.},\n\tmonth = jan,\n\tyear = {2017},\n\tkeywords = {Restoration and Management},\n\tpages = {116--124},\n}\n\n
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\n Virginia supported the most productive bay scallop (Argopecten irradians) fishery in the United States in 1930, but the fishery disappeared three years later and never recovered. This collapse highlights a tipping point, but managers of extant bay scallop fisheries have not looked to this case for guidance, because the collapse has long been attributed to an exogenous eelgrass (Zostera marina) ‘wasting disease’ pandemic. Consequently, it remains little understood. However, efforts to restore the fishery, following successful eelgrass restoration, now warrant a thorough examination of its economic significance and disappearance. This study comprehensively surveyed information on the original fishery and reconstructed the pre-collapse population to evaluate restoration prospects and management strategies that reduce the risk of future scallop-seagrass system collapses. Harvest records suggest that overharvesting possibly contributed to the Virginia fishery disappearance—a factor that influenced other bay scallop fisheries but did not alarm contemporary managers in Virginia. The harvest peaked before managers observed eelgrass disappearing and exceeded most pre-collapse population estimates. Intensive dredging possibly precipitated a feedback that reduced scallop recruitment by lowering seagrass shoot densities. Managers should, therefore, consider a potential tradeoff between future scallop harvest and eelgrass restoration goals. The restored wild scallop population in Virginia cannot yet support a commercial fishery at historic levels, which removed between 270 and 380x as many individuals. However, the economic risks associated with reestablishing this fishery are low. The collapse did not cause a significant loss in total economic value, because harvesters rapidly shifted focus to clams, supplanting lost scallop revenue.\n
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\n \n\n \n \n \n \n \n \n Restored Eelgrass (Zostera marina L.) as a Refuge for Epifaunal Biodiversity in Mid-Western Atlantic Coastal Bays.\n \n \n \n \n\n\n \n Lefcheck, J. S.; Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries and Coasts, 40(1): 200–212. January 2017.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"RestoredPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{lefcheck_restored_2017,\n\ttitle = {Restored {Eelgrass} ({Zostera} marina {L}.) as a {Refuge} for {Epifaunal} {Biodiversity} in {Mid}-{Western} {Atlantic} {Coastal} {Bays}},\n\tvolume = {40},\n\tissn = {1559-2731},\n\turl = {https://doi.org/10.1007/s12237-016-0141-x},\n\tdoi = {10.1007/s12237-016-0141-x},\n\tabstract = {As nearshore ecosystems are increasingly degraded by human activities, active restoration is a critical strategy in ensuring the continued provision of goods and services by coastal habitats. After being absent for nearly six decades, over 1800 ha of the foundational species eelgrass (Zostera marina L.) has been successfully re-established in the coastal bays of the mid-western Atlantic, USA, but nothing is known about the recovery of associated animal communities in this region. Here, we determine the patterns and drivers of functional recovery in epifaunal invertebrates associated with the restored eelgrass habitat from 2001 to 2013. After less than a decade, the invertebrate community in the restored bed was richer, more even, and exhibited greater variation in functional traits than a nearby reference bed. Analysis of a suite of environmental and physical variables using random forests revealed these differences were primarily due to the increasing area and density of eelgrass, a direct consequence of ongoing restoration efforts. Based on analysis of functional traits, we propose that the rapid life histories of constituent organisms may have played a key role in their successful recovery. We also speculate that diverse epifaunal communities may have contributed to the restoration success through a well-described mutualism with eelgrass. Given that restored eelgrass now make up 32 \\% of total seagrass cover in the mid-Atlantic coastal bays, this restoration may conserve regional biodiversity by providing new and pristine habitat, particularly given the general decline of existing eelgrass in this region.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Lefcheck, Jonathan S. and Marion, Scott R. and Orth, Robert J.},\n\tmonth = jan,\n\tyear = {2017},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {200--212},\n}\n\n
\n
\n\n\n
\n As nearshore ecosystems are increasingly degraded by human activities, active restoration is a critical strategy in ensuring the continued provision of goods and services by coastal habitats. After being absent for nearly six decades, over 1800 ha of the foundational species eelgrass (Zostera marina L.) has been successfully re-established in the coastal bays of the mid-western Atlantic, USA, but nothing is known about the recovery of associated animal communities in this region. Here, we determine the patterns and drivers of functional recovery in epifaunal invertebrates associated with the restored eelgrass habitat from 2001 to 2013. After less than a decade, the invertebrate community in the restored bed was richer, more even, and exhibited greater variation in functional traits than a nearby reference bed. Analysis of a suite of environmental and physical variables using random forests revealed these differences were primarily due to the increasing area and density of eelgrass, a direct consequence of ongoing restoration efforts. Based on analysis of functional traits, we propose that the rapid life histories of constituent organisms may have played a key role in their successful recovery. We also speculate that diverse epifaunal communities may have contributed to the restoration success through a well-described mutualism with eelgrass. Given that restored eelgrass now make up 32 % of total seagrass cover in the mid-Atlantic coastal bays, this restoration may conserve regional biodiversity by providing new and pristine habitat, particularly given the general decline of existing eelgrass in this region.\n
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\n \n\n \n \n \n \n \n \n Ecosystem services returned through seagrass restoration.\n \n \n \n \n\n\n \n Reynolds, L. K.; Waycott, M.; McGlathery, K. J.; and Orth, R. J.\n\n\n \n\n\n\n Restoration Ecology, 24(5): 583–588. 2016.\n Number: 5 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/rec.12360\n\n\n\n
\n\n\n\n \n \n \"EcosystemPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{reynolds_ecosystem_2016,\n\ttitle = {Ecosystem services returned through seagrass restoration},\n\tvolume = {24},\n\tcopyright = {© 2016 Society for Ecological Restoration},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.12360},\n\tdoi = {10.1111/rec.12360},\n\tabstract = {Ecosystem restoration is often costly, but can be effective at increasing biodiversity and ecosystem services. We used a case study—reseeding seagrass to a coastal lagoon—to demonstrate the value of enhanced ecosystem services as a result of restoration. We modeled the recovery of areal plant coverage in a system where seagrasses were lost due to disease and disturbance, and estimated the value of the returned functions of nitrogen removal and carbon sequestration. We estimated, as of 2010, that this restoration removes 170 ton of nitrogen per year via denitrificiation and sequesters carbon at a rate of 630 tons carbon per year in the sediment. Further, we estimated that natural recovery would take more than 100 years to reach the areal coverage achieved by restoration using seeds in just 10 years. Restoration enhanced this recovery, and the earlier establishment of plants results in a net gain of at least 4,100 ton of nitrogen removed from the system via denitrification and 15,000 ton of carbon sequestered in the sediment. These services have significant ecological and societal value.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Reynolds, Laura K. and Waycott, Michelle and McGlathery, Karen J. and Orth, Robert J.},\n\tyear = {2016},\n\tnote = {Number: 5\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/rec.12360},\n\tkeywords = {Restoration and Management},\n\tpages = {583--588},\n}\n\n
\n
\n\n\n
\n Ecosystem restoration is often costly, but can be effective at increasing biodiversity and ecosystem services. We used a case study—reseeding seagrass to a coastal lagoon—to demonstrate the value of enhanced ecosystem services as a result of restoration. We modeled the recovery of areal plant coverage in a system where seagrasses were lost due to disease and disturbance, and estimated the value of the returned functions of nitrogen removal and carbon sequestration. We estimated, as of 2010, that this restoration removes 170 ton of nitrogen per year via denitrificiation and sequesters carbon at a rate of 630 tons carbon per year in the sediment. Further, we estimated that natural recovery would take more than 100 years to reach the areal coverage achieved by restoration using seeds in just 10 years. Restoration enhanced this recovery, and the earlier establishment of plants results in a net gain of at least 4,100 ton of nitrogen removed from the system via denitrification and 15,000 ton of carbon sequestered in the sediment. These services have significant ecological and societal value.\n
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\n \n\n \n \n \n \n \n \n Global analysis of seagrass restoration: the importance of large-scale planting.\n \n \n \n \n\n\n \n Katwijk, M. M. v.; Thorhaug, A.; Marbà, N.; Orth, R. J.; Duarte, C. M.; Kendrick, G. A.; Althuizen, I. H. J.; Balestri, E.; Bernard, G.; Cambridge, M. L.; Cunha, A.; Durance, C.; Giesen, W.; Han, Q.; Hosokawa, S.; Kiswara, W.; Komatsu, T.; Lardicci, C.; Lee, K.; Meinesz, A.; Nakaoka, M.; O'Brien, K. R.; Paling, E. I.; Pickerell, C.; Ransijn, A. M. A.; and Verduin, J. J.\n\n\n \n\n\n\n Journal of Applied Ecology, 53(2): 567–578. 2016.\n Number: 2 _eprint: https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2664.12562\n\n\n\n
\n\n\n\n \n \n \"GlobalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{katwijk_global_2016,\n\ttitle = {Global analysis of seagrass restoration: the importance of large-scale planting},\n\tvolume = {53},\n\tcopyright = {© 2015 The Authors. Journal of Applied Ecology © 2015 British Ecological Society},\n\tissn = {1365-2664},\n\tshorttitle = {Global analysis of seagrass restoration},\n\turl = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2664.12562},\n\tdoi = {10.1111/1365-2664.12562},\n\tabstract = {In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in. From our world-wide meta-analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and natural causes. Proximity to and recovery of donor beds were positively correlated with trial performance. Planting techniques can influence restoration success. The meta-analysis shows that both trial survival and seagrass population growth rate in trials that survived are positively affected by the number of plants or seeds initially transplanted. This relationship between restoration scale and restoration success was not related to trial characteristics of the initial restoration. The majority of the seagrass restoration trials have been very small, which may explain the low overall trial survival rate (i.e. estimated 37\\%). Successful regrowth of the foundation seagrass species appears to require crossing a minimum threshold of reintroduced individuals. Our study provides the first global field evidence for the requirement of a critical mass for recovery, which may also hold for other foundation species showing strong positive feedback to a dynamic environment. Synthesis and applications. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large-scale planting increases trial survival – large numbers ensure the spread of risks, which is needed to overcome high natural variability. Secondly, a large-scale trial increases population growth rate by enhancing self-sustaining feedback, which is generally found in foundation species in stressful environments such as seagrass beds. Thus, by careful site selection and applying appropriate techniques, spreading of risks and enhancing self-sustaining feedback in concert increase success of seagrass restoration.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-05-13},\n\tjournal = {Journal of Applied Ecology},\n\tauthor = {Katwijk, Marieke M. van and Thorhaug, Anitra and Marbà, Núria and Orth, Robert J. and Duarte, Carlos M. and Kendrick, Gary A. and Althuizen, Inge H. J. and Balestri, Elena and Bernard, Guillaume and Cambridge, Marion L. and Cunha, Alexandra and Durance, Cynthia and Giesen, Wim and Han, Qiuying and Hosokawa, Shinya and Kiswara, Wawan and Komatsu, Teruhisa and Lardicci, Claudio and Lee, Kun-Seop and Meinesz, Alexandre and Nakaoka, Masahiro and O'Brien, Katherine R. and Paling, Erik I. and Pickerell, Chris and Ransijn, Aryan M. A. and Verduin, Jennifer J.},\n\tyear = {2016},\n\tnote = {Number: 2\n\\_eprint: https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2664.12562},\n\tkeywords = {Restoration and Management},\n\tpages = {567--578},\n}\n\n
\n
\n\n\n
\n In coastal and estuarine systems, foundation species like seagrasses, mangroves, saltmarshes or corals provide important ecosystem services. Seagrasses are globally declining and their reintroduction has been shown to restore ecosystem functions. However, seagrass restoration is often challenging, given the dynamic and stressful environment that seagrasses often grow in. From our world-wide meta-analysis of seagrass restoration trials (1786 trials), we describe general features and best practice for seagrass restoration. We confirm that removal of threats is important prior to replanting. Reduced water quality (mainly eutrophication), and construction activities led to poorer restoration success than, for instance, dredging, local direct impact and natural causes. Proximity to and recovery of donor beds were positively correlated with trial performance. Planting techniques can influence restoration success. The meta-analysis shows that both trial survival and seagrass population growth rate in trials that survived are positively affected by the number of plants or seeds initially transplanted. This relationship between restoration scale and restoration success was not related to trial characteristics of the initial restoration. The majority of the seagrass restoration trials have been very small, which may explain the low overall trial survival rate (i.e. estimated 37%). Successful regrowth of the foundation seagrass species appears to require crossing a minimum threshold of reintroduced individuals. Our study provides the first global field evidence for the requirement of a critical mass for recovery, which may also hold for other foundation species showing strong positive feedback to a dynamic environment. Synthesis and applications. For effective restoration of seagrass foundation species in its typically dynamic, stressful environment, introduction of large numbers is seen to be beneficial and probably serves two purposes. First, a large-scale planting increases trial survival – large numbers ensure the spread of risks, which is needed to overcome high natural variability. Secondly, a large-scale trial increases population growth rate by enhancing self-sustaining feedback, which is generally found in foundation species in stressful environments such as seagrass beds. Thus, by careful site selection and applying appropriate techniques, spreading of risks and enhancing self-sustaining feedback in concert increase success of seagrass restoration.\n
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\n \n\n \n \n \n \n \n \n Upgrading Marine Ecosystem Restoration Using Ecological‐Social Concepts.\n \n \n \n \n\n\n \n Abelson, A.; Halpern, B. S.; Reed, D. C.; Orth, R. J.; Kendrick, G. A.; Beck, M. W.; Belmaker, J.; Krause, G.; Edgar, G. J.; Airoldi, L.; Brokovich, E.; France, R.; Shashar, N.; de Blaeij, A.; Stambler, N.; Salameh, P.; Shechter, M.; and Nelson, P. A.\n\n\n \n\n\n\n BioScience, 66(2): 156–163. February 2016.\n Number: 2 Publisher: Oxford Academic\n\n\n\n
\n\n\n\n \n \n \"UpgradingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{abelson_upgrading_2016,\n\ttitle = {Upgrading {Marine} {Ecosystem} {Restoration} {Using} {Ecological}‐{Social} {Concepts}},\n\tvolume = {66},\n\tissn = {0006-3568},\n\turl = {https://academic.oup.com/bioscience/article/66/2/156/2468668},\n\tdoi = {10.1093/biosci/biv171},\n\tabstract = {Abstract.  Conservation and environmental management are principal countermeasures to the degradation of marine ecosystems and their services. However, in many},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-05-13},\n\tjournal = {BioScience},\n\tauthor = {Abelson, Avigdor and Halpern, Benjamin S. and Reed, Daniel C. and Orth, Robert J. and Kendrick, Gary A. and Beck, Michael W. and Belmaker, Jonathan and Krause, Gesche and Edgar, Graham J. and Airoldi, Laura and Brokovich, Eran and France, Robert and Shashar, Nadav and de Blaeij, Arianne and Stambler, Noga and Salameh, Pierre and Shechter, Mordechai and Nelson, Peter A.},\n\tmonth = feb,\n\tyear = {2016},\n\tnote = {Number: 2\nPublisher: Oxford Academic},\n\tkeywords = {Restoration and Management},\n\tpages = {156--163},\n}\n\n
\n
\n\n\n
\n Abstract. Conservation and environmental management are principal countermeasures to the degradation of marine ecosystems and their services. However, in many\n
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\n \n\n \n \n \n \n \n \n The Central Role of Dispersal in the Maintenance and Persistence of Seagrass Populations.\n \n \n \n \n\n\n \n Kendrick, G. A.; Waycott, M.; Carruthers, T. J. B.; Cambridge, M. L.; Hovey, R.; Krauss, S. L.; Lavery, P. S.; Les, D. H.; Lowe, R. J.; Vidal, O. M. i; Ooi, J. L. S.; Orth, R. J.; Rivers, D. O.; Ruiz-Montoya, L.; Sinclair, E. A.; Statton, J.; van Dijk, J. K.; and Verduin, J. J.\n\n\n \n\n\n\n BioScience, 62(1): 56–65. January 2012.\n Number: 1 Publisher: Oxford Academic\n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{kendrick_central_2012,\n\ttitle = {The {Central} {Role} of {Dispersal} in the {Maintenance} and {Persistence} of {Seagrass} {Populations}},\n\tvolume = {62},\n\tissn = {0006-3568},\n\turl = {https://academic.oup.com/bioscience/article/62/1/56/295569},\n\tdoi = {10.1525/bio.2012.62.1.10},\n\tabstract = {Abstract.  Global seagrass losses parallel significant declines observed in corals and mangroves over the past 50 years. These combined declines have resulted i},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {BioScience},\n\tauthor = {Kendrick, Gary A. and Waycott, Michelle and Carruthers, Tim J. B. and Cambridge, Marion L. and Hovey, Renae and Krauss, Siegfried L. and Lavery, Paul S. and Les, Donald H. and Lowe, Ryan J. and Vidal, Oriol Mascaró i and Ooi, Jillian L. S. and Orth, Robert J. and Rivers, David O. and Ruiz-Montoya, Leonardo and Sinclair, Elizabeth A. and Statton, John and van Dijk, Jent Kornelis and Verduin, Jennifer J.},\n\tmonth = jan,\n\tyear = {2012},\n\tnote = {Number: 1\nPublisher: Oxford Academic},\n\tkeywords = {Restoration and Management},\n\tpages = {56--65},\n}\n\n
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\n Abstract. Global seagrass losses parallel significant declines observed in corals and mangroves over the past 50 years. These combined declines have resulted i\n
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\n \n\n \n \n \n \n \n \n Seed addition facilitates eelgrass recovery in a coastal bay system.\n \n \n \n \n\n\n \n Orth, R. J.; Moore, K. A.; Marion, S. R.; Wilcox, D. J.; and Parrish, D. B.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 177–195. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"SeedPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_seed_2012,\n\ttitle = {Seed addition facilitates eelgrass recovery in a coastal bay system},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p177-195/},\n\tdoi = {10.3354/meps09522},\n\tabstract = {Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those exports. Estimates of annual patch vegetative expansion showed mean estimated diameter increasing at varying rates from 10 to 36 cm yr−1, consistent with rhizome elongation rates reported for Z. marina. Water quality data collected over 7 yr by spatially intensive sampling, as well as fixed-location continuous monitoring, document conditions in all 4 bays that are adequate to support Z. marina growth. In particular, median chlorophyll levels for the entire sampling period were between 5 and 6 µg l−1 for each of the bays, and median turbidity levels, while exhibiting seasonal differences, were between 8 and 9 NTU. The recovery of Z. marina initiated in this coastal bay system may be unique in seagrass recovery studies because of how the recovery was initiated (seeds rather than adult plants), how rapidly it occurred (years rather than decades), and the explicit demonstration of how one meadow modulated water clarity and altered sediments as it developed and expanded. Our results offer a new perspective on the role seeds can play in recovery dynamics at large spatial scales.},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Orth, Robert J. and Moore, Kenneth A. and Marion, Scott R. and Wilcox, David J. and Parrish, David B.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Restoration and Management},\n\tpages = {177--195},\n}\n\n
\n
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\n Eleven years of eelgrass Zostera marina seed additions conducted in a coastal bay system where Z. marina had not been reported since 1933 have resulted in rapid Z. marina expansion beyond the initially seeded plots. From 1999 through 2010, 37.8 million viable seeds were added to 369 individual plots ranging in size from 0.01 to 2 ha totaling 125.2 ha in 4 coastal bays. Subsequent expansion from these initial plots to approximately 1700 ha of bay bottom populated with Z. marina through 2010 is attributable to seed export from the original plots and subsequent generations of seedlings originating from those exports. Estimates of annual patch vegetative expansion showed mean estimated diameter increasing at varying rates from 10 to 36 cm yr−1, consistent with rhizome elongation rates reported for Z. marina. Water quality data collected over 7 yr by spatially intensive sampling, as well as fixed-location continuous monitoring, document conditions in all 4 bays that are adequate to support Z. marina growth. In particular, median chlorophyll levels for the entire sampling period were between 5 and 6 µg l−1 for each of the bays, and median turbidity levels, while exhibiting seasonal differences, were between 8 and 9 NTU. The recovery of Z. marina initiated in this coastal bay system may be unique in seagrass recovery studies because of how the recovery was initiated (seeds rather than adult plants), how rapidly it occurred (years rather than decades), and the explicit demonstration of how one meadow modulated water clarity and altered sediments as it developed and expanded. Our results offer a new perspective on the role seeds can play in recovery dynamics at large spatial scales.\n
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\n \n\n \n \n \n \n \n \n Seedling establishment in eelgrass: seed burial effects on winter losses of developing seedlings.\n \n \n \n \n\n\n \n Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Marine Ecology Progress Series, 448: 197–207. February 2012.\n \n\n\n\n
\n\n\n\n \n \n \"SeedlingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{marion_seedling_2012,\n\ttitle = {Seedling establishment in eelgrass: seed burial effects on winter losses of developing seedlings},\n\tvolume = {448},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Seedling establishment in eelgrass},\n\turl = {https://www.int-res.com/abstracts/meps/v448/p197-207/},\n\tdoi = {10.3354/meps09612},\n\tabstract = {Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked in separate destructively-sampled plots. Sediment height change was measured, and sediment disturbance depth was estimated by deploying cores layered with tracer particles and examining tracer loss upon core retrieval. We found a low rate of seedling establishment 6 mo after seeding (1.2, 3.8, and 2.8\\% for surface seeds at the 3 sites) that was largely due to seed and seedling loss rather than to germination failure, with 90\\% of seeds retrieved after December having germinated. Seed burial significantly enhanced seedling establishment at 2 of 3 sites (40.4, 16.8, and 10.3\\% establishment for buried seeds). Seed loss occurred mostly within the first month of the experiment, and was most severe for seeds at the sediment surface. Indicator core results showed widespread disturbance of sediments to depths that could have dislodged early seedlings developing from surface seeds, and to a lesser degree seedlings from buried seeds. Our findings help identify the nature and timing of a substantial Z. marina seedling establishment bottleneck in our region, and show that some of the key processes pivotal to Z. marina recruitment dynamics and optimal restoration strategies involve physical sediment−seedling interactions rather than seed germination.},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Marion, Scott R. and Orth, Robert J.},\n\tmonth = feb,\n\tyear = {2012},\n\tkeywords = {Restoration and Management},\n\tpages = {197--207},\n}\n\n
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\n Constraints on the transition of seeds to seedlings have the potential to control plant dispersal and persistence. We investigated the processes leading to low initial seedling establishment in eelgrass Zostera marina through a manipulative field experiment assessing the relative importance of germination failure and seedling loss during the winter. Seed plots were established in October at 3 unvegetated sites in the Chesapeake Bay (USA) region, with seeds either at the sediment surface or buried at 2 to 3 cm. Emerging seedlings were monitored at 6 wk intervals between December and April using a video camera, and seed germination was tracked in separate destructively-sampled plots. Sediment height change was measured, and sediment disturbance depth was estimated by deploying cores layered with tracer particles and examining tracer loss upon core retrieval. We found a low rate of seedling establishment 6 mo after seeding (1.2, 3.8, and 2.8% for surface seeds at the 3 sites) that was largely due to seed and seedling loss rather than to germination failure, with 90% of seeds retrieved after December having germinated. Seed burial significantly enhanced seedling establishment at 2 of 3 sites (40.4, 16.8, and 10.3% establishment for buried seeds). Seed loss occurred mostly within the first month of the experiment, and was most severe for seeds at the sediment surface. Indicator core results showed widespread disturbance of sediments to depths that could have dislodged early seedlings developing from surface seeds, and to a lesser degree seedlings from buried seeds. Our findings help identify the nature and timing of a substantial Z. marina seedling establishment bottleneck in our region, and show that some of the key processes pivotal to Z. marina recruitment dynamics and optimal restoration strategies involve physical sediment−seedling interactions rather than seed germination.\n
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\n \n\n \n \n \n \n \n Extinction Risk Assessment of the World's Seagrass Species.\n \n \n \n\n\n \n Short, F.; Polidoro, B.; Livingstone, S.; Carpenter, K.; Salomao, B.; Bujang, J. S.; Calumpong, H.; Carruthers, T.; Coles, R.; Dennison, W.; Erftemeijer, P.; Fortes, M.; Freeman, A.; Jagtap, T.; Kamal, A. H.; Kendrick, G.; Kenworthy, W.; La Nafie, Y.; Nasution, I.; and Zieman, J.\n\n\n \n\n\n\n Biological Conservation, 144: 1961–1971. May 2011.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{short_extinction_2011,\n\ttitle = {Extinction {Risk} {Assessment} of the {World}'s {Seagrass} {Species}},\n\tvolume = {144},\n\tdoi = {10.1016/j.biocon.2011.04.010},\n\tabstract = {Seagrasses, a functional group of marine flowering plants rooted in the world's coastal oceans, support marine food webs and provide essential habitat for many coastal species, playing a critical role in the equilibrium of coastal ecosystems and human livelihoods. For the first time, the probability of extinction is determined for the world's seagrass species under the Categories and Criteria of the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. Several studies have indicated that seagrass habitat is declining worldwide. Our focus is to determine the risk of extinction for individual seagrass species, a 4-year process involving seagrass experts internationally, compilation of data on species' status, populations, and distribution, and review of the biology and ecology of each of the world's seagrass species. Ten seagrass species are at elevated risk of extinction (14\\% of all seagrass species), with three species qualifying as Endangered. Seagrass species loss and degradation of seagrass biodiversity will have serious repercussions for marine biodiversity and the human populations that depend upon the resources and ecosystem services that seagrasses provide.},\n\tjournal = {Biological Conservation},\n\tauthor = {Short, Frederick and Polidoro, Beth and Livingstone, Suzanne and Carpenter, Kent and Salomao, Bandeira and Bujang, Japar Sidik and Calumpong, Hilconida and Carruthers, Tim and Coles, Robert and Dennison, William and Erftemeijer, Paul and Fortes, Miguel and Freeman, Aaren and Jagtap, T.G. and Kamal, Abu Hena and Kendrick, Gary and Kenworthy, W. and La Nafie, Yayu and Nasution, Ichwan and Zieman, Joseph},\n\tmonth = may,\n\tyear = {2011},\n\tkeywords = {Restoration and Management},\n\tpages = {1961--1971},\n}\n\n
\n
\n\n\n
\n Seagrasses, a functional group of marine flowering plants rooted in the world's coastal oceans, support marine food webs and provide essential habitat for many coastal species, playing a critical role in the equilibrium of coastal ecosystems and human livelihoods. For the first time, the probability of extinction is determined for the world's seagrass species under the Categories and Criteria of the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. Several studies have indicated that seagrass habitat is declining worldwide. Our focus is to determine the risk of extinction for individual seagrass species, a 4-year process involving seagrass experts internationally, compilation of data on species' status, populations, and distribution, and review of the biology and ecology of each of the world's seagrass species. Ten seagrass species are at elevated risk of extinction (14% of all seagrass species), with three species qualifying as Endangered. Seagrass species loss and degradation of seagrass biodiversity will have serious repercussions for marine biodiversity and the human populations that depend upon the resources and ecosystem services that seagrasses provide.\n
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\n \n\n \n \n \n \n \n \n Seagrass habitat loss and fragmentation influence management strategies for a blue crab Callinectes sapidus fishery.\n \n \n \n \n\n\n \n Mizerek, T.; Regan, H. M.; and Hovel, K. A.\n\n\n \n\n\n\n Marine Ecology Progress Series, 427: 247–257. April 2011.\n \n\n\n\n
\n\n\n\n \n \n \"SeagrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{mizerek_seagrass_2011,\n\ttitle = {Seagrass habitat loss and fragmentation influence management strategies for a blue crab {Callinectes} sapidus fishery},\n\tvolume = {427},\n\tissn = {0171-8630, 1616-1599},\n\turl = {https://www.int-res.com/abstracts/meps/v427/p247-257/},\n\tdoi = {10.3354/meps09021},\n\tabstract = {Marine biodiversity is increasingly threatened by multiple processes, and management strategies therefore must explicitly address the synergistic effects of multiple threats to marine species. The effects of harvesting and habitat degradation may be magnified for many coastal marine fishery species that rely on structurally complex nursery habitats to enhance survival and growth of postlarval and juvenile life history stages. Fishery management strategies that do not account for processes reducing juvenile survival and growth may overestimate the amount of biomass that can be taken; similarly, conservation and restoration strategies for nursery habitats that do not account for variable recruitment may fail. We used the blue crab Callinectes sapidus as a case study to investigate the population-level effects of harvest and seagrass habitat loss and fragmentation. We used available data to parameterize a stochastic stage-based model to test combinations of management strategies, namely reduced harvest rates and introductions of juvenile crabs to nursery habitat. Under a no-harvest scenario, large continuous areas of seagrass supported the largest blue crab populations. However, when harvest rates exceeded 20\\%, median population abundance was maximized in seascapes composed of smaller, fragmented seagrass patches. Populations in isolated patches of seagrass benefitted more from the introduction of crabs rather than harvest reduction, but the opposite was true for crab populations inhabiting highly connected seagrass seascapes. Management of species that use seagrass beds as nursery habitat must consider the spatial context of multiple threats and their potential synergies to maintain population persistence.},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Mizerek, Toni and Regan, Helen M. and Hovel, Kevin A.},\n\tmonth = apr,\n\tyear = {2011},\n\tkeywords = {Restoration and Management},\n\tpages = {247--257},\n}\n\n
\n
\n\n\n
\n Marine biodiversity is increasingly threatened by multiple processes, and management strategies therefore must explicitly address the synergistic effects of multiple threats to marine species. The effects of harvesting and habitat degradation may be magnified for many coastal marine fishery species that rely on structurally complex nursery habitats to enhance survival and growth of postlarval and juvenile life history stages. Fishery management strategies that do not account for processes reducing juvenile survival and growth may overestimate the amount of biomass that can be taken; similarly, conservation and restoration strategies for nursery habitats that do not account for variable recruitment may fail. We used the blue crab Callinectes sapidus as a case study to investigate the population-level effects of harvest and seagrass habitat loss and fragmentation. We used available data to parameterize a stochastic stage-based model to test combinations of management strategies, namely reduced harvest rates and introductions of juvenile crabs to nursery habitat. Under a no-harvest scenario, large continuous areas of seagrass supported the largest blue crab populations. However, when harvest rates exceeded 20%, median population abundance was maximized in seascapes composed of smaller, fragmented seagrass patches. Populations in isolated patches of seagrass benefitted more from the introduction of crabs rather than harvest reduction, but the opposite was true for crab populations inhabiting highly connected seagrass seascapes. Management of species that use seagrass beds as nursery habitat must consider the spatial context of multiple threats and their potential synergies to maintain population persistence.\n
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\n \n\n \n \n \n \n \n \n Spatial Patterns in Water Quality Associated with Submersed Plant Beds.\n \n \n \n \n\n\n \n Gruber, R. K.; Hinkle, D. C.; and Kemp, W. M.\n\n\n \n\n\n\n Estuaries and Coasts, 34(5): 961–972. September 2011.\n Number: 5\n\n\n\n
\n\n\n\n \n \n \"SpatialPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{gruber_spatial_2011,\n\ttitle = {Spatial {Patterns} in {Water} {Quality} {Associated} with {Submersed} {Plant} {Beds}},\n\tvolume = {34},\n\tissn = {1559-2731},\n\turl = {https://doi.org/10.1007/s12237-010-9368-0},\n\tdoi = {10.1007/s12237-010-9368-0},\n\tabstract = {This study describes the influence of submersed plant beds on spatial distributions of key water quality variables. An on-board flow-through water sampling system was used to investigate patterns in turbidity, chlorophyll-a, temperature, dissolved oxygen, and pH across a robust stand of the submersed plant Stuckenia pectinata. Spatially interpolated maps show that water quality conditions were significantly altered within this plant bed, especially during months of peak biomass, and that reduction of suspended particles focused at the bed’s edge. Comparison with a suite of submersed plant beds indicated that patterns were related to canopy height, shoot density, and cross-shore bed width. Wide and dense stands with tall canopies showed reduced turbidity and increased light penetration, while smaller sparser beds often showed elevated within-bed turbidity. These results suggest that bed effects on water quality conditions vary seasonally with plant canopy architecture and bed size, providing tentative guidelines for restoring self-sustaining beds.},\n\tlanguage = {en},\n\tnumber = {5},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Gruber, Renee K. and Hinkle, Deborah C. and Kemp, W. Michael},\n\tmonth = sep,\n\tyear = {2011},\n\tnote = {Number: 5},\n\tkeywords = {Restoration and Management},\n\tpages = {961--972},\n}\n\n
\n
\n\n\n
\n This study describes the influence of submersed plant beds on spatial distributions of key water quality variables. An on-board flow-through water sampling system was used to investigate patterns in turbidity, chlorophyll-a, temperature, dissolved oxygen, and pH across a robust stand of the submersed plant Stuckenia pectinata. Spatially interpolated maps show that water quality conditions were significantly altered within this plant bed, especially during months of peak biomass, and that reduction of suspended particles focused at the bed’s edge. Comparison with a suite of submersed plant beds indicated that patterns were related to canopy height, shoot density, and cross-shore bed width. Wide and dense stands with tall canopies showed reduced turbidity and increased light penetration, while smaller sparser beds often showed elevated within-bed turbidity. These results suggest that bed effects on water quality conditions vary seasonally with plant canopy architecture and bed size, providing tentative guidelines for restoring self-sustaining beds.\n
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\n \n\n \n \n \n \n \n \n Protocols for Use of Potamogeton perfoliatus and Ruppia maritima Seeds in Large-Scale Restoration.\n \n \n \n \n\n\n \n Ailstock, M. S.; Shafer, D. J.; and Magoun, A. D.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 560–573. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00696.x\n\n\n\n
\n\n\n\n \n \n \"ProtocolsPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{ailstock_protocols_2010,\n\ttitle = {Protocols for {Use} of {Potamogeton} perfoliatus and {Ruppia} maritima {Seeds} in {Large}-{Scale} {Restoration}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00696.x},\n\tdoi = {10.1111/j.1526-100X.2010.00696.x},\n\tabstract = {Restoration of submerged aquatic vegetation from seed has been hampered by a lack of information on the appropriate conditions for collecting, processing, and storing seeds prior to dispersal. Seeds must be processed and stored under conditions that maintain seed viability, meet dormancy requirements, and prevent premature germination. This study examined the effects of collection date, processing technique, aeration, storage and induction temperature and salinity, and storage period on seed germination of two mesohaline aquatic species, Potamogeton perfoliatus and Ruppia maritima. Collection date and processing technique were significant factors affecting seed yield from donor populations. Seeds of both species remained viable and germinated best when stored at 4°C, and then exposed to freshwater induction conditions. However, their responses to other factors differed. Aeration during storage was necessary in order to maintain viability of P. perfoliatus seeds, whereas it was unnecessary for R. maritima seeds. Storage in freshwater at 4°C prevented germination of P. perfoliatus seeds, while high salinity during cold storage was necessary to minimize premature germination of R. maritima. Mean germination time of P. perfoliatus was dependent on storage salinity; in contrast, mean germination time of R. maritima seeds was dependent on induction salinity. These differences indicate that the methods required to produce large quantities of underwater plant seed amenable to large-scale restoration efforts must be tailored to the specific requirements of individual species and must consider the range of processes from initial harvest through seed testing prior to field establishment.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Ailstock, M. Stephen and Shafer, Deborah J. and Magoun, A. Dale},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00696.x},\n\tkeywords = {Restoration and Management},\n\tpages = {560--573},\n}\n\n
\n
\n\n\n
\n Restoration of submerged aquatic vegetation from seed has been hampered by a lack of information on the appropriate conditions for collecting, processing, and storing seeds prior to dispersal. Seeds must be processed and stored under conditions that maintain seed viability, meet dormancy requirements, and prevent premature germination. This study examined the effects of collection date, processing technique, aeration, storage and induction temperature and salinity, and storage period on seed germination of two mesohaline aquatic species, Potamogeton perfoliatus and Ruppia maritima. Collection date and processing technique were significant factors affecting seed yield from donor populations. Seeds of both species remained viable and germinated best when stored at 4°C, and then exposed to freshwater induction conditions. However, their responses to other factors differed. Aeration during storage was necessary in order to maintain viability of P. perfoliatus seeds, whereas it was unnecessary for R. maritima seeds. Storage in freshwater at 4°C prevented germination of P. perfoliatus seeds, while high salinity during cold storage was necessary to minimize premature germination of R. maritima. Mean germination time of P. perfoliatus was dependent on storage salinity; in contrast, mean germination time of R. maritima seeds was dependent on induction salinity. These differences indicate that the methods required to produce large quantities of underwater plant seed amenable to large-scale restoration efforts must be tailored to the specific requirements of individual species and must consider the range of processes from initial harvest through seed testing prior to field establishment.\n
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\n \n\n \n \n \n \n \n \n Effects of Planting Depth, Sediment Grain Size, and Nutrients on Ruppia maritima and Potamogeton perfoliatus Seedling Emergence and Growth.\n \n \n \n \n\n\n \n Ailstock, M. S.; Shafer, D. J.; and Magoun, A. D.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 574–583. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00697.x\n\n\n\n
\n\n\n\n \n \n \"EffectsPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{ailstock_effects_2010,\n\ttitle = {Effects of {Planting} {Depth}, {Sediment} {Grain} {Size}, and {Nutrients} on {Ruppia} maritima and {Potamogeton} perfoliatus {Seedling} {Emergence} and {Growth}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00697.x},\n\tdoi = {10.1111/j.1526-100X.2010.00697.x},\n\tabstract = {Protocols are now available for seed harvest, storage and germination of several mesohaline and polyhaline species; however, low seedling survival rates point to the need for an increased understanding of factors affecting seedling establishment. Depth of seed burial in sediments and initial seedling growth rates are shown to be limiting factors for photosynthetic competency of Ruppia maritima and Potamogeton perfoliatus. Seedling emergence is inversely proportional to planting depth on sediments ranging in grain size from coarse sands (850 μm) to silt (63 μm). Less than 6\\% of the seeds of either species emerged when buried to a depth of 3 cm in test sediments. Germination was greatest for seeds placed on the surface of sediments; however, these seedlings were subject to displacement because of the weak and fragile roots produced during early growth. Fine sediments may be more favorable for R. maritima seedling establishment, because seedling emergence and height decreased with increasing sediment grain size. Potamogeton perfoliatus seedlings seem to be more tolerant of a wider range of sediment grain sizes than R. maritima as indicated by the lack of an effect of sediment grain size on P. perfoliatus seed emergence, seedling height, and biomass. Increasing nutrients stimulated seedlings of both species; however, even at the highest concentrations tested, growth, as determined by shoot elongation and leaf and root formation, slowed within 7–10 days. This suggests factors other than mineral nutrients and light limit growth or that growth shifts from aboveground biomass production to belowground vegetative spread.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Ailstock, M. Stephen and Shafer, Deborah J. and Magoun, A. Dale},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00697.x},\n\tkeywords = {Restoration and Management},\n\tpages = {574--583},\n}\n\n
\n
\n\n\n
\n Protocols are now available for seed harvest, storage and germination of several mesohaline and polyhaline species; however, low seedling survival rates point to the need for an increased understanding of factors affecting seedling establishment. Depth of seed burial in sediments and initial seedling growth rates are shown to be limiting factors for photosynthetic competency of Ruppia maritima and Potamogeton perfoliatus. Seedling emergence is inversely proportional to planting depth on sediments ranging in grain size from coarse sands (850 μm) to silt (63 μm). Less than 6% of the seeds of either species emerged when buried to a depth of 3 cm in test sediments. Germination was greatest for seeds placed on the surface of sediments; however, these seedlings were subject to displacement because of the weak and fragile roots produced during early growth. Fine sediments may be more favorable for R. maritima seedling establishment, because seedling emergence and height decreased with increasing sediment grain size. Potamogeton perfoliatus seedlings seem to be more tolerant of a wider range of sediment grain sizes than R. maritima as indicated by the lack of an effect of sediment grain size on P. perfoliatus seed emergence, seedling height, and biomass. Increasing nutrients stimulated seedlings of both species; however, even at the highest concentrations tested, growth, as determined by shoot elongation and leaf and root formation, slowed within 7–10 days. This suggests factors other than mineral nutrients and light limit growth or that growth shifts from aboveground biomass production to belowground vegetative spread.\n
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\n \n\n \n \n \n \n \n \n Large-Scale Zostera marina (eelgrass) Restoration in Chesapeake Bay, Maryland, USA. Part I: A Comparison of Techniques and Associated Costs.\n \n \n \n \n\n\n \n Busch, K. E.; Golden, R. R.; Parham, T. A.; Karrh, L. P.; Lewandowski, M. J.; and Naylor, M. D.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 490–500. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00690.x\n\n\n\n
\n\n\n\n \n \n \"Large-ScalePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{busch_large-scale_2010,\n\ttitle = {Large-{Scale} {Zostera} marina (eelgrass) {Restoration} in {Chesapeake} {Bay}, {Maryland}, {USA}. {Part} {I}: {A} {Comparison} of {Techniques} and {Associated} {Costs}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\tshorttitle = {Large-{Scale} {Zostera} marina (eelgrass) {Restoration} in {Chesapeake} {Bay}, {Maryland}, {USA}. {Part} {I}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00690.x},\n\tdoi = {10.1111/j.1526-100X.2010.00690.x},\n\tabstract = {The Chesapeake Bay, like many other temperate estuaries, has exhibited dramatic declines in the abundance of submerged aquatic vegetation (SAV) during the later half of the twentieth century. Because of the functions SAV serve in maintaining a healthy estuarine ecosystem, SAV restoration has become an important component of Chesapeake Bay restoration. Specifically, recent water quality improvements in areas from which populations of Zostera marina (eelgrass) have been extirpated have suggested that Z. marina restoration could succeed. Early restoration efforts involved transplanting Z. marina plants from healthy source beds to restoration locations, but this was labor intensive, time consuming, expensive, and potentially detrimental to donor beds. This multi-year project investigated new techniques for large-scale Z. marina seed collection and processing and compared two seed dispersal methods to evaluate cost effectiveness. Tens of millions of mature Z. marina seeds were collected through snorkeling, SCUBA, or with a mechanical harvester. Seed storage conditions and processing techniques were manipulated in order to maximize seed yield. Seeds were dispersed using two methods: spring seed buoys and fall seed broadcasts. Our costs for planting 1 ha of bottom with Z. marina seeds ranged from \\$6,674 to \\$165,699 depending on seeding density and dispersal method used. The average cost per Z. marina seed was \\$0.17. Interannual variations in seed collection yield and seed viability after summer storage had great impact on final costs. Our results suggest that the use of seeds for large-scale Z. marina restoration offers a competitive advantage to more traditional transplanting methods.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Busch, Kathryn E. and Golden, Rebecca R. and Parham, Thomas A. and Karrh, Lee P. and Lewandowski, Mark J. and Naylor, Michael D.},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00690.x},\n\tkeywords = {Restoration and Management},\n\tpages = {490--500},\n}\n\n
\n
\n\n\n
\n The Chesapeake Bay, like many other temperate estuaries, has exhibited dramatic declines in the abundance of submerged aquatic vegetation (SAV) during the later half of the twentieth century. Because of the functions SAV serve in maintaining a healthy estuarine ecosystem, SAV restoration has become an important component of Chesapeake Bay restoration. Specifically, recent water quality improvements in areas from which populations of Zostera marina (eelgrass) have been extirpated have suggested that Z. marina restoration could succeed. Early restoration efforts involved transplanting Z. marina plants from healthy source beds to restoration locations, but this was labor intensive, time consuming, expensive, and potentially detrimental to donor beds. This multi-year project investigated new techniques for large-scale Z. marina seed collection and processing and compared two seed dispersal methods to evaluate cost effectiveness. Tens of millions of mature Z. marina seeds were collected through snorkeling, SCUBA, or with a mechanical harvester. Seed storage conditions and processing techniques were manipulated in order to maximize seed yield. Seeds were dispersed using two methods: spring seed buoys and fall seed broadcasts. Our costs for planting 1 ha of bottom with Z. marina seeds ranged from $6,674 to $165,699 depending on seeding density and dispersal method used. The average cost per Z. marina seed was $0.17. Interannual variations in seed collection yield and seed viability after summer storage had great impact on final costs. Our results suggest that the use of seeds for large-scale Z. marina restoration offers a competitive advantage to more traditional transplanting methods.\n
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\n \n\n \n \n \n \n \n \n Large-Scale Zostera marina (eelgrass) Restoration in Chesapeake Bay, Maryland, USA. Part II: A Comparison of Restoration Methods in the Patuxent and Potomac Rivers.\n \n \n \n \n\n\n \n Golden, R. R.; Busch, K. E.; Karrh, L. P.; Parham, T. A.; Lewandowski, M. J.; and Naylor, M. D.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 501–513. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00691.x\n\n\n\n
\n\n\n\n \n \n \"Large-ScalePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{golden_large-scale_2010,\n\ttitle = {Large-{Scale} {Zostera} marina (eelgrass) {Restoration} in {Chesapeake} {Bay}, {Maryland}, {USA}. {Part} {II}: {A} {Comparison} of {Restoration} {Methods} in the {Patuxent} and {Potomac} {Rivers}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\tshorttitle = {Large-{Scale} {Zostera} marina (eelgrass) {Restoration} in {Chesapeake} {Bay}, {Maryland}, {USA}. {Part} {II}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00691.x},\n\tdoi = {10.1111/j.1526-100X.2010.00691.x},\n\tabstract = {In response to systemic losses of submerged aquatic vegetation (SAV) in the Chesapeake Bay (east coast of North America), the U.S. Environmental Protection Agency's (EPA) Chesapeake Bay Program (CBP) and Maryland Department of Natural Resources (MD DNR) have considered SAV restoration a critical component in Bay restoration programs. In 2003, the CBP created the “Strategy to Accelerate the Protection and Restoration of Submerged Aquatic Vegetation in the Chesapeake Bay” in an effort to increase SAV area. As part of this strategy, large-scale eelgrass (Zostera marina) restoration efforts were initiated in the Patuxent and Potomac Rivers in Maryland. From 2004 to 2007, nearly 4 million Z. marina seeds were dispersed over 10 ha on the Patuxent River and almost 9 million seeds over 16 ha on the Potomac River. Z. marina seedling establishment was consistent throughout the project ({\\textless}4\\%); however, restored eelgrass survival was highly dependent on restoration site. Restoration locations on the Patuxent River experienced initial Z. marina seedling germination, but no long-term plant survival. Restored Z. marina on the Potomac River has persisted and expanded, both vegetatively and sexually, beyond initial seeding areas. Healthy Z. marina beds now cover approximately five acres of the Potomac River bottom for the first time in decades. The differential success of Z. marina restoration efforts in the two rivers is evidence for the necessity of carefully considering site-specific characteristics when using large-scale seeding methods to achieve successful SAV restoration.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Golden, Rebecca R. and Busch, Kathryn E. and Karrh, Lee P. and Parham, Thomas A. and Lewandowski, Mark J. and Naylor, Michael D.},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00691.x},\n\tkeywords = {Restoration and Management},\n\tpages = {501--513},\n}\n\n
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\n In response to systemic losses of submerged aquatic vegetation (SAV) in the Chesapeake Bay (east coast of North America), the U.S. Environmental Protection Agency's (EPA) Chesapeake Bay Program (CBP) and Maryland Department of Natural Resources (MD DNR) have considered SAV restoration a critical component in Bay restoration programs. In 2003, the CBP created the “Strategy to Accelerate the Protection and Restoration of Submerged Aquatic Vegetation in the Chesapeake Bay” in an effort to increase SAV area. As part of this strategy, large-scale eelgrass (Zostera marina) restoration efforts were initiated in the Patuxent and Potomac Rivers in Maryland. From 2004 to 2007, nearly 4 million Z. marina seeds were dispersed over 10 ha on the Patuxent River and almost 9 million seeds over 16 ha on the Potomac River. Z. marina seedling establishment was consistent throughout the project (\\textless4%); however, restored eelgrass survival was highly dependent on restoration site. Restoration locations on the Patuxent River experienced initial Z. marina seedling germination, but no long-term plant survival. Restored Z. marina on the Potomac River has persisted and expanded, both vegetatively and sexually, beyond initial seeding areas. Healthy Z. marina beds now cover approximately five acres of the Potomac River bottom for the first time in decades. The differential success of Z. marina restoration efforts in the two rivers is evidence for the necessity of carefully considering site-specific characteristics when using large-scale seeding methods to achieve successful SAV restoration.\n
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\n \n\n \n \n \n \n \n \n Estuarine Restoration of Submersed Aquatic Vegetation: The Nursery Bed Effect.\n \n \n \n \n\n\n \n Hengst, A.; Melton, J.; and Murray, L.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 605–614. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00700.x\n\n\n\n
\n\n\n\n \n \n \"EstuarinePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{hengst_estuarine_2010,\n\ttitle = {Estuarine {Restoration} of {Submersed} {Aquatic} {Vegetation}: {The} {Nursery} {Bed} {Effect}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\tshorttitle = {Estuarine {Restoration} of {Submersed} {Aquatic} {Vegetation}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00700.x},\n\tdoi = {10.1111/j.1526-100X.2010.00700.x},\n\tabstract = {The historic decline of submersed aquatic vegetation (SAV) in mesohaline regions of Chesapeake Bay, United States involved a diversity of plant species. The recent modest recovery is mostly, however, associated with a single, prolific but ephemeral species, Ruppia maritima. Two previously abundant and more stable species, Potamogeton perfoliatus and Stuckenia pectinata, have shown virtually no evidence of recovery. Based on previous studies that demonstrated the ability of R. maritima stands to enhance water clarity and nutrient conditions for SAV growth, we hypothesized that these beds would serve as effective “nursery” areas to incite transplant success for other SAV. We conducted experiments in a two-phase study at small and large spatial scales designed to explore this “nursery effect” as a restoration approach to increase plant species diversity. The first phase was conducted at small spatial scales to test effects of patch density by planting P. perfoliatus and S. pectinata into bare, sparse, and densely vegetated areas within three similar R. maritima beds in a tributary of Chesapeake Bay. Mean seasonal percent survivorship and shoot density were significantly higher in bare patches compared to vegetated patches. In the second phase of the study, P. perfoliatus was transplanted into separate R. maritima beds of different densities to test the effect of bed scale plant density on P. perfoliatus survival and growth. Transplant success of P. perfoliatus was positively correlated with the density of R. maritima among all sites.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Hengst, Angela and Melton, John and Murray, Laura},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00700.x},\n\tkeywords = {Restoration and Management},\n\tpages = {605--614},\n}\n\n
\n
\n\n\n
\n The historic decline of submersed aquatic vegetation (SAV) in mesohaline regions of Chesapeake Bay, United States involved a diversity of plant species. The recent modest recovery is mostly, however, associated with a single, prolific but ephemeral species, Ruppia maritima. Two previously abundant and more stable species, Potamogeton perfoliatus and Stuckenia pectinata, have shown virtually no evidence of recovery. Based on previous studies that demonstrated the ability of R. maritima stands to enhance water clarity and nutrient conditions for SAV growth, we hypothesized that these beds would serve as effective “nursery” areas to incite transplant success for other SAV. We conducted experiments in a two-phase study at small and large spatial scales designed to explore this “nursery effect” as a restoration approach to increase plant species diversity. The first phase was conducted at small spatial scales to test effects of patch density by planting P. perfoliatus and S. pectinata into bare, sparse, and densely vegetated areas within three similar R. maritima beds in a tributary of Chesapeake Bay. Mean seasonal percent survivorship and shoot density were significantly higher in bare patches compared to vegetated patches. In the second phase of the study, P. perfoliatus was transplanted into separate R. maritima beds of different densities to test the effect of bed scale plant density on P. perfoliatus survival and growth. Transplant success of P. perfoliatus was positively correlated with the density of R. maritima among all sites.\n
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\n \n\n \n \n \n \n \n \n The Role of Currents and Waves in the Dispersal of Submersed Angiosperm Seeds and Seedlings.\n \n \n \n \n\n\n \n Koch, E. W.; Ailstock, M. S.; Booth, D. M.; Shafer, D. J.; and Magoun, A. D.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 584–595. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00698.x\n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{koch_role_2010,\n\ttitle = {The {Role} of {Currents} and {Waves} in the {Dispersal} of {Submersed} {Angiosperm} {Seeds} and {Seedlings}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00698.x},\n\tdoi = {10.1111/j.1526-100X.2010.00698.x},\n\tabstract = {We tested the hypothesis that currents, waves, and sediment grain size affect the dispersal of seeds and seedlings of the submersed angiosperms Ruppia maritima, Potamogeton perfoliatus and Stuckenia pectinata. Seed settling velocities and initiation of motion of seeds and seedlings and distance transported were quantified on four sediment types under a range of currents and waves in a flume. The rapid settling velocities of R. maritima and S. pectinata seeds and the increased settling velocity of P. perfoliatus in currents above 8 cm/second suggest that primary dispersal of these species is localized to the general area colonized by their parents. Once settled within a bed, seeds are exposed to weak currents and waves, and are likely to be subject to sediment deposition which may further limit dispersal. In contrast, in restoration projects, the absence of vegetation is likely to make seeds more vulnerable to grazing and transport, and may contribute to the lack of plant establishment. If seeds germinate without being buried, they are susceptible to secondary dispersal at relatively low current velocities and small wave heights due to the drag exerted on the cotyledon. Sand grains tend to stick to the seed coat and rootlet of P. perfoliatus seedlings, perhaps a mechanism to reduce the chances of being displaced following germination. These data reveal the close links between sediment, water flow, and submersed angiosperm seedling establishment; these parameters should be considered when using seeds for restoration of submersed angiosperms.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Koch, Evamaria W. and Ailstock, M. Stephen and Booth, Dale M. and Shafer, Deborah J. and Magoun, A. Dale},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00698.x},\n\tkeywords = {Restoration and Management},\n\tpages = {584--595},\n}\n\n
\n
\n\n\n
\n We tested the hypothesis that currents, waves, and sediment grain size affect the dispersal of seeds and seedlings of the submersed angiosperms Ruppia maritima, Potamogeton perfoliatus and Stuckenia pectinata. Seed settling velocities and initiation of motion of seeds and seedlings and distance transported were quantified on four sediment types under a range of currents and waves in a flume. The rapid settling velocities of R. maritima and S. pectinata seeds and the increased settling velocity of P. perfoliatus in currents above 8 cm/second suggest that primary dispersal of these species is localized to the general area colonized by their parents. Once settled within a bed, seeds are exposed to weak currents and waves, and are likely to be subject to sediment deposition which may further limit dispersal. In contrast, in restoration projects, the absence of vegetation is likely to make seeds more vulnerable to grazing and transport, and may contribute to the lack of plant establishment. If seeds germinate without being buried, they are susceptible to secondary dispersal at relatively low current velocities and small wave heights due to the drag exerted on the cotyledon. Sand grains tend to stick to the seed coat and rootlet of P. perfoliatus seedlings, perhaps a mechanism to reduce the chances of being displaced following germination. These data reveal the close links between sediment, water flow, and submersed angiosperm seedling establishment; these parameters should be considered when using seeds for restoration of submersed angiosperms.\n
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\n \n\n \n \n \n \n \n \n Innovative Techniques for Large-scale Seagrass Restoration Using Zostera marina (eelgrass) Seeds.\n \n \n \n \n\n\n \n Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 514–526. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00692.x\n\n\n\n
\n\n\n\n \n \n \"InnovativePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{marion_innovative_2010,\n\ttitle = {Innovative {Techniques} for {Large}-scale {Seagrass} {Restoration} {Using} {Zostera} marina (eelgrass) {Seeds}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00692.x},\n\tdoi = {10.1111/j.1526-100X.2010.00692.x},\n\tabstract = {The use of Zostera marina (eelgrass) seeds for seagrass restoration is increasingly recognized as an alternative to transplanting shoots as losses of seagrass habitat generate interest in large-scale restoration. We explored new techniques for efficient large-scale restoration of Z. marina using seeds by addressing the factors limiting seed collection, processing, survival, and distribution. We tested an existing mechanical harvesting system for expanding the scale of seed collections, and developed and evaluated two new experimental systems. A seeding technique using buoys holding reproductive shoots at restoration sites to eliminate seed storage was tested along with new techniques for reducing seed-processing labor. A series of experiments evaluated storage conditions that maintain viability of seeds during summer storage for fall planting. Finally, a new mechanical seed-planting technique appropriate for large scales was developed and tested. Mechanical harvesting was an effective approach for collecting seeds, and impacts on donor beds were low. Deploying seed-bearing shoots in buoys produced fewer seedlings and required more effort than isolating, storing, and hand-broadcasting seeds in the fall. We show that viable seeds can be separated from grass wrack based on seed fall velocity and that seed survival during storage can be high (92–95\\% survival over 3 months). Mechanical seed-planting did not enhance seedling establishment at our sites, but may be a useful tool for evaluating restoration sites. Our work demonstrates the potential for expanding the scale of seed-based Z. marina restoration but the limiting factor remains the low rate of initial seedling establishment from broadcast seeds.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Marion, Scott R. and Orth, Robert J.},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00692.x},\n\tkeywords = {Restoration and Management},\n\tpages = {514--526},\n}\n\n
\n
\n\n\n
\n The use of Zostera marina (eelgrass) seeds for seagrass restoration is increasingly recognized as an alternative to transplanting shoots as losses of seagrass habitat generate interest in large-scale restoration. We explored new techniques for efficient large-scale restoration of Z. marina using seeds by addressing the factors limiting seed collection, processing, survival, and distribution. We tested an existing mechanical harvesting system for expanding the scale of seed collections, and developed and evaluated two new experimental systems. A seeding technique using buoys holding reproductive shoots at restoration sites to eliminate seed storage was tested along with new techniques for reducing seed-processing labor. A series of experiments evaluated storage conditions that maintain viability of seeds during summer storage for fall planting. Finally, a new mechanical seed-planting technique appropriate for large scales was developed and tested. Mechanical harvesting was an effective approach for collecting seeds, and impacts on donor beds were low. Deploying seed-bearing shoots in buoys produced fewer seedlings and required more effort than isolating, storing, and hand-broadcasting seeds in the fall. We show that viable seeds can be separated from grass wrack based on seed fall velocity and that seed survival during storage can be high (92–95% survival over 3 months). Mechanical seed-planting did not enhance seedling establishment at our sites, but may be a useful tool for evaluating restoration sites. Our work demonstrates the potential for expanding the scale of seed-based Z. marina restoration but the limiting factor remains the low rate of initial seedling establishment from broadcast seeds.\n
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\n \n\n \n \n \n \n \n \n Factors Influencing Seedling Establishment Rates in Zostera marina and Their Implications for Seagrass Restoration.\n \n \n \n \n\n\n \n Marion, S. R.; and Orth, R. J.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 549–559. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00695.x\n\n\n\n
\n\n\n\n \n \n \"FactorsPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{marion_factors_2010,\n\ttitle = {Factors {Influencing} {Seedling} {Establishment} {Rates} in {Zostera} marina and {Their} {Implications} for {Seagrass} {Restoration}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00695.x},\n\tdoi = {10.1111/j.1526-100X.2010.00695.x},\n\tabstract = {Selection of strategies to efficiently utilize limited seed supplies in efforts to restore the seagrass Zostera marina (eelgrass) requires a better understanding of the processes that limit seedling establishment at potential restoration sites. We investigated the effect of seed distribution timing on seedling establishment and tested for interactive effects of seed burial and distribution timing. We also investigated the effect of habitat type on seedling establishment by distributing Z. marina seeds inside and outside of established Ruppia maritima (widgeongrass) patches and examined mechanisms causing habitat differences by manipulating seed position (buried or unburied) and vulnerability to seed predators (unprotected or protected in packets). Seeds distributed on the sediment surface in the summer (July or August) produced fewer seedlings than seeds distributed in fall (October) in five of six trials over 3 years. Seed burial increased success rates for seeds distributed in summer at one of two sites tested, eliminating the effect of season, but reduced success at the other site. Seeds placed in R. maritima generally produced fewer seedlings than seeds in bare sand, and although seed burial and protection in packets increased success in bare sand at three of four sites, the effect was less consistent in R. maritima. We conclude that seed predation and physical interactions were influential in reducing seedling establishment in R. maritima, contrary to hypotheses positing a nursery role for existing vegetation. Efficient restoration efforts with Z. marina seeds should target unvegetated areas after summertime sources of mortality have diminished. Direct seed burial may enhance seedling establishment rates.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Marion, Scott R. and Orth, Robert J.},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00695.x},\n\tkeywords = {Restoration and Management},\n\tpages = {549--559},\n}\n\n
\n
\n\n\n
\n Selection of strategies to efficiently utilize limited seed supplies in efforts to restore the seagrass Zostera marina (eelgrass) requires a better understanding of the processes that limit seedling establishment at potential restoration sites. We investigated the effect of seed distribution timing on seedling establishment and tested for interactive effects of seed burial and distribution timing. We also investigated the effect of habitat type on seedling establishment by distributing Z. marina seeds inside and outside of established Ruppia maritima (widgeongrass) patches and examined mechanisms causing habitat differences by manipulating seed position (buried or unburied) and vulnerability to seed predators (unprotected or protected in packets). Seeds distributed on the sediment surface in the summer (July or August) produced fewer seedlings than seeds distributed in fall (October) in five of six trials over 3 years. Seed burial increased success rates for seeds distributed in summer at one of two sites tested, eliminating the effect of season, but reduced success at the other site. Seeds placed in R. maritima generally produced fewer seedlings than seeds in bare sand, and although seed burial and protection in packets increased success in bare sand at three of four sites, the effect was less consistent in R. maritima. We conclude that seed predation and physical interactions were influential in reducing seedling establishment in R. maritima, contrary to hypotheses positing a nursery role for existing vegetation. Efficient restoration efforts with Z. marina seeds should target unvegetated areas after summertime sources of mortality have diminished. Direct seed burial may enhance seedling establishment rates.\n
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\n \n\n \n \n \n \n \n \n The Role of Habitat and Herbivory on the Restoration of Tidal Freshwater Submerged Aquatic Vegetation Populations.\n \n \n \n \n\n\n \n Moore, K. A.; Shields, E. C.; and Jarvis, J. C.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 596–604. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00699.x\n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{moore_role_2010,\n\ttitle = {The {Role} of {Habitat} and {Herbivory} on the {Restoration} of {Tidal} {Freshwater} {Submerged} {Aquatic} {Vegetation} {Populations}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00699.x},\n\tdoi = {10.1111/j.1526-100X.2010.00699.x},\n\tabstract = {Submerged aquatic vegetation (SAV) has declined precipitously throughout coastal areas and its reestablishment has long been an important objective of coastal management. We investigated restoration success of Vallisneria americana (wild celery) using seeds, seed pods, and whole shoot transplants at sites in the Chesapeake Bay in the United States where historical aerial photography has indicated that the species once grew. In addition, we evaluated habitat conditions and established herbivore exclosures to assess the impacts of water quality, sediment conditions, and grazers on planting success. Whole shoot transplants resulted in the most rapid cover of the bottom, but required greater planting effort. Direct dispersal of individual seeds was generally more successful than dispersal of intact seed pods, resulting in more rapid initial seedling growth. Overall, 100\\% bottom cover of whole shoot transplant plots could be reached in approximately 3 years, despite light attenuation coefficients (Kd) of 3.0 to 4.0. Transplants at shallow depths ({\\textless}0.5 m) were able to rapidly grow and elongate to the surface at mid-to-low tidal heights. Transplants were successful in both muddy (8\\% organic) and sandy ({\\textless}2\\%) substrates. Using mesh exclosures to protect the plants from herbivory was critical to restoration success. Although water quality and other habitat conditions are important for SAV growth and survival, restoration in the unvegetated areas studied here was limited by grazing of initial recruits. The establishment of protected founder colonies of sufficient size to withstand initial grazing pressures may be required to reestablish SAV in similar areas.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Moore, Kenneth A. and Shields, Erin C. and Jarvis, Jessie C.},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00699.x},\n\tkeywords = {Restoration and Management},\n\tpages = {596--604},\n}\n\n
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\n Submerged aquatic vegetation (SAV) has declined precipitously throughout coastal areas and its reestablishment has long been an important objective of coastal management. We investigated restoration success of Vallisneria americana (wild celery) using seeds, seed pods, and whole shoot transplants at sites in the Chesapeake Bay in the United States where historical aerial photography has indicated that the species once grew. In addition, we evaluated habitat conditions and established herbivore exclosures to assess the impacts of water quality, sediment conditions, and grazers on planting success. Whole shoot transplants resulted in the most rapid cover of the bottom, but required greater planting effort. Direct dispersal of individual seeds was generally more successful than dispersal of intact seed pods, resulting in more rapid initial seedling growth. Overall, 100% bottom cover of whole shoot transplant plots could be reached in approximately 3 years, despite light attenuation coefficients (Kd) of 3.0 to 4.0. Transplants at shallow depths (\\textless0.5 m) were able to rapidly grow and elongate to the surface at mid-to-low tidal heights. Transplants were successful in both muddy (8% organic) and sandy (\\textless2%) substrates. Using mesh exclosures to protect the plants from herbivory was critical to restoration success. Although water quality and other habitat conditions are important for SAV growth and survival, restoration in the unvegetated areas studied here was limited by grazing of initial recruits. The establishment of protected founder colonies of sufficient size to withstand initial grazing pressures may be required to reestablish SAV in similar areas.\n
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\n \n\n \n \n \n \n \n \n Eelgrass (Zostera marina L.) in the Chesapeake Bay Region of Mid-Atlantic Coast of the USA: Challenges in Conservation and Restoration.\n \n \n \n \n\n\n \n Orth, R. J.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Estuaries and Coasts, 33(1): 139–150. January 2010.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"EelgrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_eelgrass_2010,\n\ttitle = {Eelgrass ({Zostera} marina {L}.) in the {Chesapeake} {Bay} {Region} of {Mid}-{Atlantic} {Coast} of the {USA}: {Challenges} in {Conservation} and {Restoration}},\n\tvolume = {33},\n\tissn = {1559-2731},\n\tshorttitle = {Eelgrass ({Zostera} marina {L}.) in the {Chesapeake} {Bay} {Region} of {Mid}-{Atlantic} {Coast} of the {USA}},\n\turl = {https://doi.org/10.1007/s12237-009-9234-0},\n\tdoi = {10.1007/s12237-009-9234-0},\n\tabstract = {Decreases in seagrass abundance reported from numerous locations around the world suggest that seagrass are facing a global crisis. Declining water quality has been identified as the leading cause for most losses. Increased public awareness is leading to expanded efforts for conservation and restoration. Here, we report on abundance patterns and environmental issues facing eelgrass (Zostera marina), the dominant seagrass species in the Chesapeake Bay region in the mid-Atlantic coast of the USA, and describe efforts to promote its protection and restoration. Eelgrass beds in Chesapeake Bay and Chincoteague Bay, which had started to recover from earlier diebacks, have shown a downward trend in the last 5–10 years, while eelgrass beds in the Virginia coastal bays have substantially increased in abundance during this same time period. Declining water quality appears to be the primary reason for the decreased abundance, but a recent baywide dieback in 2005 was associated with higher than usual summer water temperatures along with poor water clarity. The success of eelgrass in the Virginia coastal bays has been attributed, in part, to slightly cooler water due to their proximity to the Atlantic Ocean. A number of policies and regulations have been adopted in this region since 1983 aimed at protecting and restoring both habitat and water quality. Eelgrass abundance is now one of the criteria for assessing attainment of water clarity goals in this region. Numerous transplant projects have been aimed at restoring eelgrass but most have not succeeded beyond 1 to 2 years. A notable exception is the large-scale restoration effort in the Virginia coastal bays, where seeds distributed beginning in 2001 has initiated an expanding recovery process. Our research on eelgrass abundance patterns in the Chesapeake Bay region and the processes contributing to these patterns have provided a scientific background for management strategies for the protection and restoration of eelgrass and insights into the causes of success and failure of restoration efforts that may have applications to other seagrass systems.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Orth, Robert J. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tmonth = jan,\n\tyear = {2010},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {139--150},\n}\n\n
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\n Decreases in seagrass abundance reported from numerous locations around the world suggest that seagrass are facing a global crisis. Declining water quality has been identified as the leading cause for most losses. Increased public awareness is leading to expanded efforts for conservation and restoration. Here, we report on abundance patterns and environmental issues facing eelgrass (Zostera marina), the dominant seagrass species in the Chesapeake Bay region in the mid-Atlantic coast of the USA, and describe efforts to promote its protection and restoration. Eelgrass beds in Chesapeake Bay and Chincoteague Bay, which had started to recover from earlier diebacks, have shown a downward trend in the last 5–10 years, while eelgrass beds in the Virginia coastal bays have substantially increased in abundance during this same time period. Declining water quality appears to be the primary reason for the decreased abundance, but a recent baywide dieback in 2005 was associated with higher than usual summer water temperatures along with poor water clarity. The success of eelgrass in the Virginia coastal bays has been attributed, in part, to slightly cooler water due to their proximity to the Atlantic Ocean. A number of policies and regulations have been adopted in this region since 1983 aimed at protecting and restoring both habitat and water quality. Eelgrass abundance is now one of the criteria for assessing attainment of water clarity goals in this region. Numerous transplant projects have been aimed at restoring eelgrass but most have not succeeded beyond 1 to 2 years. A notable exception is the large-scale restoration effort in the Virginia coastal bays, where seeds distributed beginning in 2001 has initiated an expanding recovery process. Our research on eelgrass abundance patterns in the Chesapeake Bay region and the processes contributing to these patterns have provided a scientific background for management strategies for the protection and restoration of eelgrass and insights into the causes of success and failure of restoration efforts that may have applications to other seagrass systems.\n
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\n \n\n \n \n \n \n \n \n Long-term reductions in anthropogenic nutrients link to improvements in Chesapeake Bay habitat.\n \n \n \n \n\n\n \n Ruhl, H. A.; and Rybicki, N. B.\n\n\n \n\n\n\n Proceedings of the National Academy of Sciences, 107(38): 16566–16570. September 2010.\n Number: 38 Publisher: National Academy of Sciences Section: Biological Sciences\n\n\n\n
\n\n\n\n \n \n \"Long-termPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{ruhl_long-term_2010,\n\ttitle = {Long-term reductions in anthropogenic nutrients link to improvements in {Chesapeake} {Bay} habitat},\n\tvolume = {107},\n\tcopyright = {©  . Freely available online through the PNAS open access option.},\n\tissn = {0027-8424, 1091-6490},\n\turl = {https://www.pnas.org/content/107/38/16566},\n\tdoi = {10.1073/pnas.1003590107},\n\tabstract = {Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990–2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.},\n\tlanguage = {en},\n\tnumber = {38},\n\turldate = {2020-05-13},\n\tjournal = {Proceedings of the National Academy of Sciences},\n\tauthor = {Ruhl, Henry A. and Rybicki, Nancy B.},\n\tmonth = sep,\n\tyear = {2010},\n\tpmid = {20823243},\n\tnote = {Number: 38\nPublisher: National Academy of Sciences\nSection: Biological Sciences},\n\tkeywords = {Restoration and Management},\n\tpages = {16566--16570},\n}\n\n
\n
\n\n\n
\n Great effort continues to focus on ecosystem restoration and reduction of nutrient inputs thought to be responsible, in part, for declines in estuary habitats worldwide. The ability of environmental policy to address restoration is limited, in part, by uncertainty in the relationships between costly restoration and benefits. Here, we present results from an 18-y field investigation (1990–2007) of submerged aquatic vegetation (SAV) community dynamics and water quality in the Potomac River, a major tributary of the Chesapeake Bay. River and anthropogenic discharges lower water clarity by introducing nutrients that stimulate phytoplankton and epiphyte growth as well as suspended sediments. Efforts to restore the Chesapeake Bay are often viewed as failing. Overall nutrient reduction and SAV restoration goals have not been met. In the Potomac River, however, reduced in situ nutrients, wastewater-treatment effluent nitrogen, and total suspended solids were significantly correlated to increased SAV abundance and diversity. Species composition and relative abundance also correlated with nutrient and water-quality conditions, indicating declining fitness of exotic species relative to native species during restoration. Our results suggest that environmental policies that reduce anthropogenic nutrient inputs do result in improved habitat quality, with increased diversity and native species abundances. The results also help elucidate why SAV cover has improved only in some areas of the Chesapeake Bay.\n
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\n \n\n \n \n \n \n \n \n An Introduction to a Special Issue on Large-Scale Submerged Aquatic Vegetation Restoration Research in the Chesapeake Bay: 2003–2008.\n \n \n \n \n\n\n \n Shafer, D.; and Bergstrom, P.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 481–489. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00689.x\n\n\n\n
\n\n\n\n \n \n \"AnPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{shafer_introduction_2010,\n\ttitle = {An {Introduction} to a {Special} {Issue} on {Large}-{Scale} {Submerged} {Aquatic} {Vegetation} {Restoration} {Research} in the {Chesapeake} {Bay}: 2003–2008},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\tshorttitle = {An {Introduction} to a {Special} {Issue} on {Large}-{Scale} {Submerged} {Aquatic} {Vegetation} {Restoration} {Research} in the {Chesapeake} {Bay}},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00689.x},\n\tdoi = {10.1111/j.1526-100X.2010.00689.x},\n\tabstract = {The Chesapeake Bay is one of the world's largest estuaries. Dramatic declines in the abundance and distribution of submerged aquatic vegetation (SAV) in the Chesapeake Bay over the last few decades led to a series of management decisions aimed at protecting and restoring SAV populations throughout the bay. In 2003, the Chesapeake Bay Program established a goal of planting 405 ha of SAV by 2008. Realizing that such an ambitious goal would require the development of large-scale approaches to SAV restoration, a comprehensive research effort was organized, involving federal and state agencies, academia, and the private sector. This effort differs from most other SAV restoration programs due to a strong emphasis on the use of seeds rather than plants as planting stock, a decision based on the relatively low labor requirements of seeding. Much of the research has focused on the development of tools and techniques for using seeds in large-scale SAV restoration. Since this research initiative began, an average of 13.4 ha/year of SAV has been planted in the Chesapeake Bay, compared to an average rate of 3.6 ha/year during the previous 21 years (1983–2003). The costs of conducting these plantings are on a downward trend as the understanding of the limiting factors increases and as new advances are made in applied research and technology development. Although this effort was focused in the Chesapeake Bay region, the tools and techniques developed as part of this research should be widely applicable to SAV restoration efforts in other areas.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Shafer, Deborah and Bergstrom, Peter},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00689.x},\n\tkeywords = {Restoration and Management},\n\tpages = {481--489},\n}\n\n
\n
\n\n\n
\n The Chesapeake Bay is one of the world's largest estuaries. Dramatic declines in the abundance and distribution of submerged aquatic vegetation (SAV) in the Chesapeake Bay over the last few decades led to a series of management decisions aimed at protecting and restoring SAV populations throughout the bay. In 2003, the Chesapeake Bay Program established a goal of planting 405 ha of SAV by 2008. Realizing that such an ambitious goal would require the development of large-scale approaches to SAV restoration, a comprehensive research effort was organized, involving federal and state agencies, academia, and the private sector. This effort differs from most other SAV restoration programs due to a strong emphasis on the use of seeds rather than plants as planting stock, a decision based on the relatively low labor requirements of seeding. Much of the research has focused on the development of tools and techniques for using seeds in large-scale SAV restoration. Since this research initiative began, an average of 13.4 ha/year of SAV has been planted in the Chesapeake Bay, compared to an average rate of 3.6 ha/year during the previous 21 years (1983–2003). The costs of conducting these plantings are on a downward trend as the understanding of the limiting factors increases and as new advances are made in applied research and technology development. Although this effort was focused in the Chesapeake Bay region, the tools and techniques developed as part of this research should be widely applicable to SAV restoration efforts in other areas.\n
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\n \n\n \n \n \n \n \n \n Growing Zostera marina (eelgrass) from Seeds in Land-Based Culture Systems for Use in Restoration Projects.\n \n \n \n \n\n\n \n Tanner, C. E.; and Parham, T.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 527–537. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00693.x\n\n\n\n
\n\n\n\n \n \n \"GrowingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{tanner_growing_2010,\n\ttitle = {Growing {Zostera} marina (eelgrass) from {Seeds} in {Land}-{Based} {Culture} {Systems} for {Use} in {Restoration} {Projects}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00693.x},\n\tdoi = {10.1111/j.1526-100X.2010.00693.x},\n\tabstract = {The use of aquaculture systems to grow the seagrass Zostera marina (eelgrass) from seeds for restoration projects was evaluated through laboratory and mesocosm studies. Along the mid-Atlantic coast of North America Z. marina seeds are shed from late spring through early summer, but seeds typically do not begin to germinate until the late fall. Fall is the optimal season to plant both seeds and shoots in this region. We conducted studies to determine if Z. marina seeds can be induced to germinate in the summer and seedlings grown in mesocosms to a size sufficiently large enough for out-planting in the fall. Seeds in soil-less culture germinated in the summer when held at 14°C, with percent germination increasing with lower salinities. Cold storage (4°C) of seeds prior to planting in sediments enhanced germination and seedling survival. Growth rates of seedlings were significantly higher in nutrient enriched estuarine sediments. Results from preliminary studies were used in designing a large-scale culture project in which 15,000 shoots were grown and out-planted into the Potomac River estuary in the Chesapeake Bay and compared with an equal number of transplanted shoots. These studies demonstrate that growing Z. marina from seeds is an alternative approach to harvesting plants from donor beds when vegetative shoots are required for restoration projects.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Tanner, Christopher E. and Parham, Thomas},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00693.x},\n\tkeywords = {Restoration and Management},\n\tpages = {527--537},\n}\n\n
\n
\n\n\n
\n The use of aquaculture systems to grow the seagrass Zostera marina (eelgrass) from seeds for restoration projects was evaluated through laboratory and mesocosm studies. Along the mid-Atlantic coast of North America Z. marina seeds are shed from late spring through early summer, but seeds typically do not begin to germinate until the late fall. Fall is the optimal season to plant both seeds and shoots in this region. We conducted studies to determine if Z. marina seeds can be induced to germinate in the summer and seedlings grown in mesocosms to a size sufficiently large enough for out-planting in the fall. Seeds in soil-less culture germinated in the summer when held at 14°C, with percent germination increasing with lower salinities. Cold storage (4°C) of seeds prior to planting in sediments enhanced germination and seedling survival. Growth rates of seedlings were significantly higher in nutrient enriched estuarine sediments. Results from preliminary studies were used in designing a large-scale culture project in which 15,000 shoots were grown and out-planted into the Potomac River estuary in the Chesapeake Bay and compared with an equal number of transplanted shoots. These studies demonstrate that growing Z. marina from seeds is an alternative approach to harvesting plants from donor beds when vegetative shoots are required for restoration projects.\n
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\n \n\n \n \n \n \n \n \n Evaluating a Large-Scale Eelgrass Restoration Project in the Chesapeake Bay.\n \n \n \n \n\n\n \n Tanner, C.; Hunter, S.; Reel, J.; Parham, T.; Naylor, M.; Karrh, L.; Busch, K.; Golden, R. R.; Lewandowski, M.; Rybicki, N.; and Schenk, E.\n\n\n \n\n\n\n Restoration Ecology, 18(4): 538–548. 2010.\n Number: 4 _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00694.x\n\n\n\n
\n\n\n\n \n \n \"EvaluatingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{tanner_evaluating_2010,\n\ttitle = {Evaluating a {Large}-{Scale} {Eelgrass} {Restoration} {Project} in the {Chesapeake} {Bay}},\n\tvolume = {18},\n\tcopyright = {© 2010 Society for Ecological Restoration International},\n\tissn = {1526-100X},\n\turl = {https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1526-100X.2010.00694.x},\n\tdoi = {10.1111/j.1526-100X.2010.00694.x},\n\tabstract = {Approximately 90,000 shoots of eelgrass (Zostera marina) were planted over 3 years (2003–2005) at Piney Point (PP) in the lower Potomac River estuary in the Chesapeake Bay (mid-Atlantic coast of North America) following 3 years of habitat evaluation using a Preliminary Transplant Suitability Index (PTSI) and test plantings. Initial survival was high for the 2003 and 2004 plantings; however, most of the eelgrass died during the summer following the fall planting. Habitat quality and restoration success were monitored for the 2005 plantings and compared to a nearby restoration site (St. George Island [SGI]). Eelgrass planted at PP in the fall of 2005 declined through the summer of 2006 with some recovery in the spring of 2007, but was gone by the end of the summer of 2007. The summer decline from late July to mid-August of 2006 coincided with water temperatures greater than 30°C, hypoxic oxygen (0–3 mg/L) concentrations, and low percent light at leaf level (PLL {\\textless} 15\\%). Epiphyte loads were much heavier at PP than at SGI, despite similar water quality. We suggest that this was the result of higher wave exposure at PP. All of these factors are likely to have contributed to the mortality of the 2005 plantings. Submerged aquatic vegetation habitat quality based on the PTSI, median PLL during the growing season, and test plantings did not explain the decline of the plantings. Restoration site selection criteria should be expanded to include the effects of wave exposure on self-shading and epiphyte loads, and the potential for both short-term exposures to stressful conditions and long-term changes in habitat quality.},\n\tlanguage = {en},\n\tnumber = {4},\n\turldate = {2020-05-13},\n\tjournal = {Restoration Ecology},\n\tauthor = {Tanner, Christopher and Hunter, Sarah and Reel, Justin and Parham, Thomas and Naylor, Mike and Karrh, Lee and Busch, Kathryn and Golden, Rebecca R. and Lewandowski, Mark and Rybicki, Nancy and Schenk, Edward},\n\tyear = {2010},\n\tnote = {Number: 4\n\\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1526-100X.2010.00694.x},\n\tkeywords = {Restoration and Management},\n\tpages = {538--548},\n}\n\n
\n
\n\n\n
\n Approximately 90,000 shoots of eelgrass (Zostera marina) were planted over 3 years (2003–2005) at Piney Point (PP) in the lower Potomac River estuary in the Chesapeake Bay (mid-Atlantic coast of North America) following 3 years of habitat evaluation using a Preliminary Transplant Suitability Index (PTSI) and test plantings. Initial survival was high for the 2003 and 2004 plantings; however, most of the eelgrass died during the summer following the fall planting. Habitat quality and restoration success were monitored for the 2005 plantings and compared to a nearby restoration site (St. George Island [SGI]). Eelgrass planted at PP in the fall of 2005 declined through the summer of 2006 with some recovery in the spring of 2007, but was gone by the end of the summer of 2007. The summer decline from late July to mid-August of 2006 coincided with water temperatures greater than 30°C, hypoxic oxygen (0–3 mg/L) concentrations, and low percent light at leaf level (PLL \\textless 15%). Epiphyte loads were much heavier at PP than at SGI, despite similar water quality. We suggest that this was the result of higher wave exposure at PP. All of these factors are likely to have contributed to the mortality of the 2005 plantings. Submerged aquatic vegetation habitat quality based on the PTSI, median PLL during the growing season, and test plantings did not explain the decline of the plantings. Restoration site selection criteria should be expanded to include the effects of wave exposure on self-shading and epiphyte loads, and the potential for both short-term exposures to stressful conditions and long-term changes in habitat quality.\n
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\n \n\n \n \n \n \n \n Long-term changes in water quality and productivity in the Patuxent River estuary: 1985 to 2003.\n \n \n \n\n\n \n Testa, J. M.; Kemp, W. M.; Boynton, W. R.; and Hagy, J. D.\n\n\n \n\n\n\n Estuaries and Coasts, 31(6): 1021–1037. 2008.\n Number: 6 ISBN: 1559-2723\n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{testa_long-term_2008,\n\ttitle = {Long-term changes in water quality and productivity in the {Patuxent} {River} estuary: 1985 to 2003},\n\tvolume = {31},\n\tdoi = {10.1007/s12237-008-9095-y},\n\tnumber = {6},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Testa, Jeremy M. and Kemp, W. Michael and Boynton, Walter R. and Hagy, James D.},\n\tyear = {2008},\n\tnote = {Number: 6\nISBN: 1559-2723},\n\tkeywords = {Restoration and Management},\n\tpages = {1021--1037},\n}\n\n
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\n \n\n \n \n \n \n \n \n The Charisma of Coastal Ecosystems: Addressing the Imbalance.\n \n \n \n \n\n\n \n Duarte, C. M.; Dennison, W. C.; Orth, R. J. W.; and Carruthers, T. J. B.\n\n\n \n\n\n\n Estuaries and Coasts, 31(2): 233–238. April 2008.\n Number: 2\n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{duarte_charisma_2008,\n\ttitle = {The {Charisma} of {Coastal} {Ecosystems}: {Addressing} the {Imbalance}},\n\tvolume = {31},\n\tissn = {1559-2731},\n\tshorttitle = {The {Charisma} of {Coastal} {Ecosystems}},\n\turl = {https://doi.org/10.1007/s12237-008-9038-7},\n\tdoi = {10.1007/s12237-008-9038-7},\n\tabstract = {Coastal ecosystems including coral reefs, mangrove forests, seagrass meadows, and salt marshes are being lost at alarming rates, and increased scientific understanding of causes has failed to stem these losses. Coastal habitats receive contrasting research effort, with 60\\% of all of the published research carried out on coral reefs, compared to 11–14\\% of the records for each of salt marshes, mangrove forests, and seagrass meadows. In addition, these highly connected and interdependent coastal ecosystems receive widely contrasting media attention that is disproportional to their scientific attention. Seagrass ecosystems receive the least attention in the media (1.3\\% of the media reports) with greater attention on salt marshes (6.5\\%), considerably more attention on mangroves (20\\%), and a dominant focus on coral reefs, which are the subject of three in every four media reports on coastal ecosystems (72.5\\%). There are approximately tenfold lower reports on seagrass meadows in the media for every scientific paper published (ten), than the 130–150 media reports per scientific paper for mangroves and coral reefs. The lack of public awareness of losses of less charismatic ecosystems results in the continuation of detrimental practices and therefore contributes to continued declines of coastal ecosystems. More effective communication of scientific knowledge about these uncharismatic but ecologically important coastal habitats is required. Effective use of formal (e.g., school curricula, media) and informal (e.g., web) education avenues and an effective partnership between scientists and media communicators are essential to raise public awareness of issues, concerns, and solutions within coastal ecosystems. Only increased public understanding can ultimately inform and motivate effective management of these ecologically important coastal ecosystems.},\n\tlanguage = {en},\n\tnumber = {2},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries and Coasts},\n\tauthor = {Duarte, Carlos M. and Dennison, William C. and Orth, Robert J. W. and Carruthers, Tim J. B.},\n\tmonth = apr,\n\tyear = {2008},\n\tnote = {Number: 2},\n\tkeywords = {Restoration and Management},\n\tpages = {233--238},\n}\n\n
\n
\n\n\n
\n Coastal ecosystems including coral reefs, mangrove forests, seagrass meadows, and salt marshes are being lost at alarming rates, and increased scientific understanding of causes has failed to stem these losses. Coastal habitats receive contrasting research effort, with 60% of all of the published research carried out on coral reefs, compared to 11–14% of the records for each of salt marshes, mangrove forests, and seagrass meadows. In addition, these highly connected and interdependent coastal ecosystems receive widely contrasting media attention that is disproportional to their scientific attention. Seagrass ecosystems receive the least attention in the media (1.3% of the media reports) with greater attention on salt marshes (6.5%), considerably more attention on mangroves (20%), and a dominant focus on coral reefs, which are the subject of three in every four media reports on coastal ecosystems (72.5%). There are approximately tenfold lower reports on seagrass meadows in the media for every scientific paper published (ten), than the 130–150 media reports per scientific paper for mangroves and coral reefs. The lack of public awareness of losses of less charismatic ecosystems results in the continuation of detrimental practices and therefore contributes to continued declines of coastal ecosystems. More effective communication of scientific knowledge about these uncharismatic but ecologically important coastal habitats is required. Effective use of formal (e.g., school curricula, media) and informal (e.g., web) education avenues and an effective partnership between scientists and media communicators are essential to raise public awareness of issues, concerns, and solutions within coastal ecosystems. Only increased public understanding can ultimately inform and motivate effective management of these ecologically important coastal ecosystems.\n
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\n \n\n \n \n \n \n \n Restoring Eelgrass (Zostera marina) from Seed: A Comparison of Planting Methods for Large-Scale Projects.\n \n \n \n\n\n \n Orth, R. J.; Marion, S. R.; Granger, S.; and Traber, M.\n\n\n \n\n\n\n In 2008. \n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@inproceedings{orth_restoring_2008,\n\ttitle = {Restoring {Eelgrass} ({Zostera} marina) from {Seed}: {A} {Comparison} of {Planting} {Methods} for {Large}-{Scale} {Projects}},\n\tshorttitle = {Restoring {Eelgrass} ({Zostera} marina) from {Seed}},\n\tdoi = {10.21236/ada478894},\n\tabstract = {Abstract : Eelgrass (Zostera marina) seeds are being used in a variety of both small- and large-scale restoration activities and have been successfully used to initiate recovery of eelgrass in the Virginia seaside coastal lagoons, which lost eelgrass in the 1930s wasting disease pandemic (Orth et al. 2006a). However, a major bottleneck with the use of seeds has been the relatively low rate of seedling establishment, generally 10 percent or less of seeds placed in the field (Orth et al. 2003). A recently developed underwater seed planter (Traber et al. 2003) represents an alternative method that could improve seedling success compared to techniques used in previous Chesapeake Bay studies and elsewhere. The objective of this study was to compare the effectiveness of different techniques of seeding for use in large-scale projects: injecting seeds into submerged sediments with a mechanical seed planter and hand-broadcasting seeds on the sediment surface using divers.},\n\tauthor = {Orth, Robert J. and Marion, Scott R. and Granger, S. and Traber, Michael},\n\tyear = {2008},\n\tkeywords = {Restoration and Management},\n}\n\n
\n
\n\n\n
\n Abstract : Eelgrass (Zostera marina) seeds are being used in a variety of both small- and large-scale restoration activities and have been successfully used to initiate recovery of eelgrass in the Virginia seaside coastal lagoons, which lost eelgrass in the 1930s wasting disease pandemic (Orth et al. 2006a). However, a major bottleneck with the use of seeds has been the relatively low rate of seedling establishment, generally 10 percent or less of seeds placed in the field (Orth et al. 2003). A recently developed underwater seed planter (Traber et al. 2003) represents an alternative method that could improve seedling success compared to techniques used in previous Chesapeake Bay studies and elsewhere. The objective of this study was to compare the effectiveness of different techniques of seeding for use in large-scale projects: injecting seeds into submerged sediments with a mechanical seed planter and hand-broadcasting seeds on the sediment surface using divers.\n
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\n \n\n \n \n \n \n \n \n Large-Scale Submerged Aquatic Vegetation Restoration in Chesapeake Bay: Status Report, 2003-2006:.\n \n \n \n \n\n\n \n Shafer, D. J.; and Bergstrom, P.\n\n\n \n\n\n\n Technical Report Defense Technical Information Center, Fort Belvoir, VA, June 2008.\n \n\n\n\n
\n\n\n\n \n \n \"Large-ScalePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@techreport{shafer_large-scale_2008,\n\taddress = {Fort Belvoir, VA},\n\ttitle = {Large-{Scale} {Submerged} {Aquatic} {Vegetation} {Restoration} in {Chesapeake} {Bay}: {Status} {Report}, 2003-2006:},\n\tshorttitle = {Large-{Scale} {Submerged} {Aquatic} {Vegetation} {Restoration} in {Chesapeake} {Bay}},\n\turl = {http://www.dtic.mil/docs/citations/ADA484280},\n\tabstract = {In 2003, the U.S. Army Engineer Research and Development Center (ERDC) and the National Oceanic and Atmospheric Administration Chesapeake Bay Office began a comprehensive research effort to restore submerged aquatic vegetation (SAV) in the Chesapeake Bay region. The effort employed an agricultural approach to restore under-water grasses by using seeds to produce new plants and mechanical equipment to plant seeds and harvest. Since this research initiative began, an average of 33 acres/yr of SAV has been planted in the Chesapeake Bay, compared to an average rate of 9 acres/yr during the previous 21 years (1983–2003). New techniques and equipment developed as part of this research have introduced the capability to collect and disperse millions of eelgrass seeds. These results demonstrate these programs’ success in developing tools and techniques necessary to plant SAV at scales unattainable with technologies existing only a few years ago.},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tinstitution = {Defense Technical Information Center},\n\tauthor = {Shafer, Deborah J. and Bergstrom, Peter},\n\tmonth = jun,\n\tyear = {2008},\n\tdoi = {10.21236/ADA484280},\n\tkeywords = {Restoration and Management},\n}\n\n
\n
\n\n\n
\n In 2003, the U.S. Army Engineer Research and Development Center (ERDC) and the National Oceanic and Atmospheric Administration Chesapeake Bay Office began a comprehensive research effort to restore submerged aquatic vegetation (SAV) in the Chesapeake Bay region. The effort employed an agricultural approach to restore under-water grasses by using seeds to produce new plants and mechanical equipment to plant seeds and harvest. Since this research initiative began, an average of 33 acres/yr of SAV has been planted in the Chesapeake Bay, compared to an average rate of 9 acres/yr during the previous 21 years (1983–2003). New techniques and equipment developed as part of this research have introduced the capability to collect and disperse millions of eelgrass seeds. These results demonstrate these programs’ success in developing tools and techniques necessary to plant SAV at scales unattainable with technologies existing only a few years ago.\n
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\n \n\n \n \n \n \n \n \n A Global Crisis for Seagrass Ecosystems.\n \n \n \n \n\n\n \n Orth, R. J.; Carruthers, T. J. B.; Dennison, W. C.; Duarte, C. M.; Fourqurean, J. W.; Heck, K. L.; Hughes, A. R.; Kendrick, G. A.; Kenworthy, W. J.; Olyarnik, S.; Short, F. T.; Waycott, M.; and Williams, S. L.\n\n\n \n\n\n\n BioScience, 56(12): 987–996. December 2006.\n Number: 12 Publisher: Oxford Academic\n\n\n\n
\n\n\n\n \n \n \"APaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_global_2006,\n\ttitle = {A {Global} {Crisis} for {Seagrass} {Ecosystems}},\n\tvolume = {56},\n\tissn = {0006-3568},\n\turl = {https://academic.oup.com/bioscience/article/56/12/987/221654},\n\tdoi = {10.1641/0006-3568(2006)56[987:AGCFSE]2.0.CO;2},\n\tabstract = {Abstract.  Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal},\n\tlanguage = {en},\n\tnumber = {12},\n\turldate = {2020-05-13},\n\tjournal = {BioScience},\n\tauthor = {Orth, Robert J. and Carruthers, Tim J. B. and Dennison, William C. and Duarte, Carlos M. and Fourqurean, James W. and Heck, Kenneth L. and Hughes, A. Randall and Kendrick, Gary A. and Kenworthy, W. Judson and Olyarnik, Suzanne and Short, Frederick T. and Waycott, Michelle and Williams, Susan L.},\n\tmonth = dec,\n\tyear = {2006},\n\tnote = {Number: 12\nPublisher: Oxford Academic},\n\tkeywords = {Restoration and Management},\n\tpages = {987--996},\n}\n\n
\n
\n\n\n
\n Abstract. Seagrasses, marine flowering plants, have a long evolutionary history but are now challenged with rapid environmental changes as a result of coastal\n
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\n \n\n \n \n \n \n \n \n Seagrass recovery in the Delmarva Coastal Bays, USA.\n \n \n \n \n\n\n \n Orth, R. J.; Luckenbach, M. L.; Marion, S. R.; Moore, K. A.; and Wilcox, D. J.\n\n\n \n\n\n\n Aquatic Botany, 84(1): 26–36. January 2006.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"SeagrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_seagrass_2006,\n\ttitle = {Seagrass recovery in the {Delmarva} {Coastal} {Bays}, {USA}},\n\tvolume = {84},\n\tissn = {0304-3770},\n\turl = {http://www.sciencedirect.com/science/article/pii/S030437700500149X},\n\tdoi = {10.1016/j.aquabot.2005.07.007},\n\tabstract = {Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319ha reported through 2003 compared to 2129ha in 1986, an average expansion rate of 305hayear−1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4m2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2ha in four coastal bays having no seagrass, totaling approximately 46ha through 2004. Successful germination (estimated at 5–10\\% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38\\% of the bottom in 52–0.4ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J. and Luckenbach, Mark L. and Marion, Scott R. and Moore, Kenneth A. and Wilcox, David J.},\n\tmonth = jan,\n\tyear = {2006},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {26--36},\n}\n\n
\n
\n\n\n
\n Zostera marina (eelgrass) in the coastal bays of the Delmarva Peninsula, USA, declined precipitously in the 1930s due to the pandemic wasting disease and a destructive hurricane in 1933. This resulted in major changes in many of the ecosystem services provided by this seagrass, such as loss of bay scallops (Argopecten irradians) and disappearance of brant (Branta bernicla). Natural recovery of Z. marina, possibly deriving from either small remnant stands or undocumented transplant projects after the demise of Z. marina, has been significant in four northern bays, with over 7319ha reported through 2003 compared to 2129ha in 1986, an average expansion rate of 305hayear−1. This rapid spread was likely due to seeds and seed dispersal from recovering beds. However, no recovery had occurred in the southern coastal bays prior to restoration efforts, possibly due to both their distance from potential donor beds, restricted entrances to the bays, and the narrow time period when seeds are available for colonization via rafting reproductive shoots carrying viable seeds. Survival and expansion of small test plots (4m2) in these southern coastal bays between 1997 and 2000 demonstrated that propagule supply, rather than water quality, was limiting seagrass recovery in these bays. In 2001, we initiated a large-scale Z. marina restoration effort in the southern coastal bays utilizing seeds, while simultaneously monitoring water quality using spatially and temporally intensive water quality mapping techniques. Between 2001 and 2004, approximately 24 million seeds harvested from natural, dense beds in Chesapeake Bay were broadcast into experimental plots ranging in size from 0.2 to 2ha in four coastal bays having no seagrass, totaling approximately 46ha through 2004. Successful germination (estimated at 5–10% of seeds broadcast), growth and expansion of Z. marina in and around these plots over this 3-year test period, as well as water quality data, suggest conditions are appropriate for plant growth. Low-level aerial photographs in 2004 showed 38% of the bottom in 52–0.4ha plots was covered by vegetation. Increasing Z. marina coverage will have important implications for fisheries and waterfowl but may potentially conflict with aquaculture, which is rapidly expanding in this region. Continued recovery will depend on maintaining good water quality to avoid the macro-algal accumulations and phytoplankton blooms that have characterized other coastal lagoons. The patterns of natural seagrass recovery and the results of restoration efforts we describe here, as well as seagrass recoveries from wasting disease outbreaks, anoxic events, hurricanes, and propeller scarring reported elsewhere, suggest that seeds and seed dispersal play an important role in the recovery and expansion of these beds.\n
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\n \n\n \n \n \n \n \n Exploring causes of a seagrass transplant failure in the Potomac River (Virginia).\n \n \n \n\n\n \n Schenk, E.; and Rybicki, N.\n\n\n \n\n\n\n Ecological Restoration, 24: 116–118. January 2006.\n \n\n\n\n
\n\n\n\n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{schenk_exploring_2006,\n\ttitle = {Exploring causes of a seagrass transplant failure in the {Potomac} {River} ({Virginia})},\n\tvolume = {24},\n\tjournal = {Ecological Restoration},\n\tauthor = {Schenk, Edward and Rybicki, Nancy},\n\tmonth = jan,\n\tyear = {2006},\n\tkeywords = {Restoration and Management},\n\tpages = {116--118},\n}\n\n
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\n \n\n \n \n \n \n \n \n Eutrophication of Chesapeake Bay: historical trends and ecological interactions.\n \n \n \n \n\n\n \n Kemp, W. M.; Boynton, W. R.; Adolf, J. E.; Boesch, D. F.; Boicourt, W. C.; Brush, G.; Cornwell, J. C.; Fisher, T. R.; Glibert, P. M.; Hagy, J. D.; Harding, L. W.; Houde, E. D.; Kimmel, D. G.; Miller, W. D.; Newell, R. I. E.; Roman, M. R.; Smith, E. M.; and Stevenson, J. C.\n\n\n \n\n\n\n Marine Ecology Progress Series, 303: 1–29. November 2005.\n \n\n\n\n
\n\n\n\n \n \n \"EutrophicationPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{kemp_eutrophication_2005,\n\ttitle = {Eutrophication of {Chesapeake} {Bay}: historical trends and ecological interactions},\n\tvolume = {303},\n\tissn = {0171-8630, 1616-1599},\n\tshorttitle = {Eutrophication of {Chesapeake} {Bay}},\n\turl = {https://www.int-res.com/abstracts/meps/v303/p1-29/},\n\tdoi = {10.3354/meps303001},\n\tabstract = {This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in {\\textasciitilde}200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared {\\textasciitilde}100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macroinfauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay’s overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest fundamental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others.},\n\tlanguage = {en},\n\turldate = {2020-05-13},\n\tjournal = {Marine Ecology Progress Series},\n\tauthor = {Kemp, W. M. and Boynton, W. R. and Adolf, J. E. and Boesch, D. F. and Boicourt, W. C. and Brush, G. and Cornwell, J. C. and Fisher, T. R. and Glibert, P. M. and Hagy, J. D. and Harding, L. W. and Houde, E. D. and Kimmel, D. G. and Miller, W. D. and Newell, R. I. E. and Roman, M. R. and Smith, E. M. and Stevenson, J. C.},\n\tmonth = nov,\n\tyear = {2005},\n\tkeywords = {Restoration and Management},\n\tpages = {1--29},\n}\n\n
\n
\n\n\n
\n This review provides an integrated synthesis with timelines and evaluations of ecological responses to eutrophication in Chesapeake Bay, the largest estuary in the USA. Analyses of dated sediment cores reveal initial evidence of organic enrichment in ~200 yr old strata, while signs of increased phytoplankton and decreased water clarity first appeared ~100 yr ago. Severe, recurring deep-water hypoxia and loss of diverse submersed vascular plants were first evident in the 1950s and 1960s, respectively. The degradation of these benthic habitats has contributed to declines in benthic macroinfauna in deep mesohaline regions of the Bay and blue crabs in shallow polyhaline areas. In contrast, copepods, which are heavily consumed in pelagic food chains, are relatively unaffected by nutrient-induced changes in phytoplankton. Intense mortality associated with fisheries and disease have caused a dramatic decline in eastern oyster stocks and associated Bay water filtration, which may have exacerbated eutrophication effects on phytoplankton and water clarity. Extensive tidal marshes, which have served as effective nutrient buffers along the Bay margins, are now being lost with rising sea level. Although the Bay’s overall fisheries production has probably not been affected by eutrophication, decreases in the relative contribution of demersal fish and in the efficiency with which primary production is transferred to harvest suggest fundamental shifts in trophic and habitat structures. Bay ecosystem responses to changes in nutrient loading are complicated by non-linear feedback mechanisms, including particle trapping and binding by benthic plants that increase water clarity, and by oxygen effects on benthic nutrient recycling efficiency. Observations in Bay tributaries undergoing recent reductions in nutrient input indicate relatively rapid recovery of some ecosystem functions but lags in the response of others.\n
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\n \n\n \n \n \n \n \n \n Habitat requirements for submerged aquatic vegetation in Chesapeake Bay: Water quality, light regime, and physical-chemical factors.\n \n \n \n \n\n\n \n Michael Kemp, W.; Batleson, R.; Bergstrom, P.; Carter, V.; Gallegos, C. L.; Hunley, W.; Karrh, L.; Koch, E. W.; Landwehr, J. M.; Moore, K. A.; Murray, L.; Naylor, M.; Rybicki, N. B.; Court Stevenson, J.; and Wilcox, D. J.\n\n\n \n\n\n\n Estuaries, 27(3): 363–377. June 2004.\n Number: 3\n\n\n\n
\n\n\n\n \n \n \"HabitatPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{michael_kemp_habitat_2004,\n\ttitle = {Habitat requirements for submerged aquatic vegetation in {Chesapeake} {Bay}: {Water} quality, light regime, and physical-chemical factors},\n\tvolume = {27},\n\tissn = {0160-8347},\n\tshorttitle = {Habitat requirements for submerged aquatic vegetation in {Chesapeake} {Bay}},\n\turl = {https://doi.org/10.1007/BF02803529},\n\tdoi = {10.1007/BF02803529},\n\tabstract = {We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing though the water column to the depth of SAV growth (PLWmin) and as a percentage of light reaching reaching leaves through the epiphyte layer (PLLmin). Value were computed by applying, as inputs to this algorithm, statistically dervived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates ofPLWmin andPLLmin compared well with the values established from a literature review. Calcultations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophylla (chla), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calculated light available at plant leaves exceededPLLmin. Predictions closely matched results of aerial photographic monitoring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polythaline regions, which contain 75–80\\% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries},\n\tauthor = {Michael Kemp, W. and Batleson, Richard and Bergstrom, Peter and Carter, Virginia and Gallegos, Charles L. and Hunley, William and Karrh, Lee and Koch, Evamaria W. and Landwehr, Jurate M. and Moore, Kenneth A. and Murray, Laura and Naylor, Michael and Rybicki, Nancy B. and Court Stevenson, J. and Wilcox, David J.},\n\tmonth = jun,\n\tyear = {2004},\n\tnote = {Number: 3},\n\tkeywords = {Restoration and Management},\n\tpages = {363--377},\n}\n\n
\n
\n\n\n
\n We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing though the water column to the depth of SAV growth (PLWmin) and as a percentage of light reaching reaching leaves through the epiphyte layer (PLLmin). Value were computed by applying, as inputs to this algorithm, statistically dervived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates ofPLWmin andPLLmin compared well with the values established from a literature review. Calcultations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophylla (chla), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calculated light available at plant leaves exceededPLLmin. Predictions closely matched results of aerial photographic monitoring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polythaline regions, which contain 75–80% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide.\n
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\n \n\n \n \n \n \n \n \n Seed-density effects on germination and initial seedling establishment in eelgrass Zostera marina in the Chesapeake Bay region.\n \n \n \n \n\n\n \n Orth, R; Fishman, J. R.; Harwell, M. C.; and Marion, S. R.\n\n\n \n\n\n\n MARINE ECOLOGY PROGRESS SERIES, 250: 71–79. January 2003.\n \n\n\n\n
\n\n\n\n \n \n \"Seed-densityPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_seed-density_2003,\n\ttitle = {Seed-density effects on germination and initial seedling establishment in eelgrass {Zostera} marina in the {Chesapeake} {Bay} region},\n\tvolume = {250},\n\turl = {https://scholarworks.wm.edu/vimsarticles/171},\n\tdoi = {<p>10.3354/meps250071</p>},\n\tjournal = {MARINE ECOLOGY PROGRESS SERIES},\n\tauthor = {Orth, R and Fishman, J. R. and Harwell, M. C. and Marion, S. R.},\n\tmonth = jan,\n\tyear = {2003},\n\tkeywords = {Restoration and Management},\n\tpages = {71--79},\n}\n\n
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\n \n\n \n \n \n \n \n \n Long-Distance Dispersal Potential in a Marine Macrophyte.\n \n \n \n \n\n\n \n Harwell, M. C.; and Orth, R. J.\n\n\n \n\n\n\n Ecology, 83(12): 3319–3330. 2002.\n Number: 12 Publisher: Ecological Society of America\n\n\n\n
\n\n\n\n \n \n \"Long-DistancePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{harwell_long-distance_2002,\n\ttitle = {Long-{Distance} {Dispersal} {Potential} in a {Marine} {Macrophyte}},\n\tvolume = {83},\n\tissn = {0012-9658},\n\turl = {https://www.jstor.org/stable/3072082},\n\tdoi = {10.2307/3072082},\n\tabstract = {Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.},\n\tnumber = {12},\n\turldate = {2020-05-13},\n\tjournal = {Ecology},\n\tauthor = {Harwell, Matthew C. and Orth, Robert J.},\n\tyear = {2002},\n\tnote = {Number: 12\nPublisher: Ecological Society of America},\n\tkeywords = {Restoration and Management},\n\tpages = {3319--3330},\n}\n\n
\n
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\n Plant populations have long been noted to migrate faster than predicted based on their life history and seed dispersal characteristics (i.e., Reid's paradox of rapid plant migration). Although precise mechanisms to account for such phenomena are not fully known for all plant species, a combination of theoretical and empirically driven mechanisms often resolves this paradox. Here, we couple a series of direct and indirect field and laboratory exercises on one marine macrophyte, Zostera marina L. (eelgrass), to measured distances between new patches and established beds in order to elucidate the long-distance dispersal and colonization potential of this marine seagrass. Detached, floating reproductive shoots with mature seeds were found to remain positively buoyant for up to 2 wk and retain mature seeds for up to 3 wk before release under laboratory conditions. Analysis of the detritus wrack along a remote shoreline found reproductive fragments with viable seeds up to 34 km from established, natural beds. Analysis of different regions of the Chesapeake Bay and coastal bays of the Delmarva Peninsula that once supported eelgrass populations, revealed natural patches at 13 sites ranging from 1 to 108 km from established populations. A combination of tidal currents and wind influences has the potential to move a passive particle at the surface (e.g., a floating reproductive fragment) up to 23 km in a 6-h tidal window suggesting that most unvegetated areas in this region that can support eelgrass are within the colonization potential envelope. We suggest that, when combined with earlier work on seed dispersal ecology of this species, eelgrass has strong qualities for high colonization potential of new habitat. The finding of natural patches at such great distances from established beds when studied in the context of the dispersal mechanism (currents and wind) make the dispersal distances of this species one of the highest for angiosperms, comparable in scale to mangroves and coconuts. This new understanding of the dispersal dynamics of eelgrass is critical in the context of seagrass restoration in areas distant from established beds, maintenance of existing populations threatened by anthropogenic inputs of sediments and nutrients, and examining metapopulation concepts in seagrass ecology.\n
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\n \n\n \n \n \n \n \n \n Impact of Boat-Generated Waves on a Seagrass Habitat.\n \n \n \n \n\n\n \n Koch, E. W.\n\n\n \n\n\n\n Journal of Coastal Research,66–74. 2002.\n Publisher: Coastal Education & Research Foundation, Inc.\n\n\n\n
\n\n\n\n \n \n \"ImpactPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{koch_impact_2002,\n\ttitle = {Impact of {Boat}-{Generated} {Waves} on a {Seagrass} {Habitat}},\n\tissn = {0749-0208},\n\turl = {https://www.jstor.org/stable/25736343},\n\tabstract = {Although previous studies proved that boats can have a negative impact on seagrasses when their anchors and/or rotating props are in direct contact with the plants, very little is known about the indirect impacts (e.g., hydrocarbon emissions, oil leaks, and waves) that boats can have on seagrasses. This study quantified the impact of boat-generated waves on a Ruppia maritima habitat in Chesapeake Bay. During a calm and clear day, a V-hulled boat was driven at two speeds through a study site in the bay at high and low tide. Waves, suspended solids, nutrients and light levels were monitored before, during, and after the boat runs. The possible negative impacts (increased sediment resuspension, release of sediment nutrients, and reduced light levels) were much smaller than expected, being minimal when compared to natural fluctuations in this habitat (conditions to which the plants have acclimated). The strongest impact was observed at low tide when boat-generated waves resuspended a small amount of sediment, which was redeposited within minutes. Boat-generated waves apparently also caused porewater pumping, which increased the concentration of ammonia in the water column. This has the potential to contribute to eutrophication and, over long periods of time, to have a negative impact on seagrass beds. High boat speeds at high tide seem to minimize detrimental conditions in seagrass habitats. In contrast, stormy and cloudy days as well as dusk and dawn, when light availability is reduced, are the most vulnerable conditions for seagrasses. Fortunately, recreational boating activity is usually reduced under these conditions.},\n\turldate = {2020-05-13},\n\tjournal = {Journal of Coastal Research},\n\tauthor = {Koch, Evamaria W.},\n\tyear = {2002},\n\tnote = {Publisher: Coastal Education \\& Research Foundation, Inc.},\n\tkeywords = {Restoration and Management},\n\tpages = {66--74},\n}\n\n
\n
\n\n\n
\n Although previous studies proved that boats can have a negative impact on seagrasses when their anchors and/or rotating props are in direct contact with the plants, very little is known about the indirect impacts (e.g., hydrocarbon emissions, oil leaks, and waves) that boats can have on seagrasses. This study quantified the impact of boat-generated waves on a Ruppia maritima habitat in Chesapeake Bay. During a calm and clear day, a V-hulled boat was driven at two speeds through a study site in the bay at high and low tide. Waves, suspended solids, nutrients and light levels were monitored before, during, and after the boat runs. The possible negative impacts (increased sediment resuspension, release of sediment nutrients, and reduced light levels) were much smaller than expected, being minimal when compared to natural fluctuations in this habitat (conditions to which the plants have acclimated). The strongest impact was observed at low tide when boat-generated waves resuspended a small amount of sediment, which was redeposited within minutes. Boat-generated waves apparently also caused porewater pumping, which increased the concentration of ammonia in the water column. This has the potential to contribute to eutrophication and, over long periods of time, to have a negative impact on seagrass beds. High boat speeds at high tide seem to minimize detrimental conditions in seagrass habitats. In contrast, stormy and cloudy days as well as dusk and dawn, when light availability is reduced, are the most vulnerable conditions for seagrasses. Fortunately, recreational boating activity is usually reduced under these conditions.\n
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\n \n\n \n \n \n \n \n \n A perspective on two decades of policies and regulations influencing the protection and restoration of submerged aquatic vegetation in Chesapeake Bay, USA.\n \n \n \n \n\n\n \n Orth, R; Batiuk, R. A.; Bergstrom, P. W.; and Moore, K.\n\n\n \n\n\n\n Bulletin of Marine Science, 71(3): 1391–1403. November 2002.\n Number: 3\n\n\n\n
\n\n\n\n \n \n \"APaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_perspective_2002,\n\ttitle = {A perspective on two decades of policies and regulations influencing the protection and restoration of submerged aquatic vegetation in {Chesapeake} {Bay}, {USA}},\n\tvolume = {71},\n\turl = {https://scholarworks.wm.edu/vimsarticles/1530},\n\tnumber = {3},\n\tjournal = {Bulletin of Marine Science},\n\tauthor = {Orth, R and Batiuk, R. A. and Bergstrom, P. W. and Moore, Ken},\n\tmonth = nov,\n\tyear = {2002},\n\tnote = {Number: 3},\n\tkeywords = {Restoration and Management},\n\tpages = {1391--1403},\n}\n\n
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\n \n\n \n \n \n \n \n \n Calculating optical water quality targets to restore and protect submersed aquatic vegetation: Overcoming problems in partitioning the diffuse attenuation coefficient for photosynthetically active radiation.\n \n \n \n \n\n\n \n Gallegos, C. L.\n\n\n \n\n\n\n Estuaries, 24(3): 381–397. June 2001.\n Number: 3\n\n\n\n
\n\n\n\n \n \n \"CalculatingPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{gallegos_calculating_2001,\n\ttitle = {Calculating optical water quality targets to restore and protect submersed aquatic vegetation: {Overcoming} problems in partitioning the diffuse attenuation coefficient for photosynthetically active radiation},\n\tvolume = {24},\n\tissn = {0160-8347},\n\tshorttitle = {Calculating optical water quality targets to restore and protect submersed aquatic vegetation},\n\turl = {https://doi.org/10.2307/1353240},\n\tdoi = {10.2307/1353240},\n\tabstract = {Submersed aquatic vegetation (SAV) is an important component of shallow water estuarine systems that has declined drastically in recent decades. SAV has particularly high light requirements, and losses of SAV have, in many cases, been attributed to increased light attenuation in the water column, frequently due to coastal eutrophication. The desire to restore these valuable habitats to their historical levels has created the need for a simple but accurate management tool for translating light requirements into water quality targets capable of supporting SAV communities. A procedure for calculating water quality targets for concentrations of chlorophyll and total suspended solids (TSS) is derived, based on representing the diffuse attenuation coefficient for photosynthetically active radiation, Kd(PAR), as a linear function of contributions due to water plus colored dissolved organic matter (CDOM), chlorophyll, and TSS. It is assumed that Kd(PAR) conforms to the Lambert-Beer law. Target concentrations are determined as the intersection of a line representing intended reduction of TSS and chlorophyll by management actions, with another line describing the dependence of TSS on chlorophyll at a constant value of Kd(PAR). The validity of applying the Lambert-Beer law to Kd(PAR) in estuarine waters was tested by comparing the performance of a linear model of Kd(PAR) with data simulated using a more realistic model of light attenuation. The linear regression model tended to underestimate Kd(PAR) at high light attenuation, resulting in erroneous predictions of target concentrations at shallow restoration depths. The errors result more from the wide spectral bandwidth of PAR, than from irrecoverable nonlinearities in the diffuse attenuation coefficient per se. In spite of the failure of the Lambert-Beer law applied to Kd(PAR), the variation of TSS with chlorophyll at constant Kd(PAR) determined by the more mechanistic attenuation model was, nevertheless, highly linear. Use of the management tool based on intersecting lines is still possible, but coefficients in the line describing the dependence of TSS on chlorophyll at constant Kd(PAR) must be determined empirically by application of an optical model suitably calibrated for the region of interest. An example application of the procedure to data from the Rhode River, Maryland, indicates that approximately 15\\% reduction in both TSS and chlorophyll concentrations, or 50\\% reduction in chlorophyll alone, will be needed to restore conditions for growth of SAV to levels that existed in the late 1960s.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries},\n\tauthor = {Gallegos, Charles L.},\n\tmonth = jun,\n\tyear = {2001},\n\tnote = {Number: 3},\n\tkeywords = {Restoration and Management},\n\tpages = {381--397},\n}\n\n
\n
\n\n\n
\n Submersed aquatic vegetation (SAV) is an important component of shallow water estuarine systems that has declined drastically in recent decades. SAV has particularly high light requirements, and losses of SAV have, in many cases, been attributed to increased light attenuation in the water column, frequently due to coastal eutrophication. The desire to restore these valuable habitats to their historical levels has created the need for a simple but accurate management tool for translating light requirements into water quality targets capable of supporting SAV communities. A procedure for calculating water quality targets for concentrations of chlorophyll and total suspended solids (TSS) is derived, based on representing the diffuse attenuation coefficient for photosynthetically active radiation, Kd(PAR), as a linear function of contributions due to water plus colored dissolved organic matter (CDOM), chlorophyll, and TSS. It is assumed that Kd(PAR) conforms to the Lambert-Beer law. Target concentrations are determined as the intersection of a line representing intended reduction of TSS and chlorophyll by management actions, with another line describing the dependence of TSS on chlorophyll at a constant value of Kd(PAR). The validity of applying the Lambert-Beer law to Kd(PAR) in estuarine waters was tested by comparing the performance of a linear model of Kd(PAR) with data simulated using a more realistic model of light attenuation. The linear regression model tended to underestimate Kd(PAR) at high light attenuation, resulting in erroneous predictions of target concentrations at shallow restoration depths. The errors result more from the wide spectral bandwidth of PAR, than from irrecoverable nonlinearities in the diffuse attenuation coefficient per se. In spite of the failure of the Lambert-Beer law applied to Kd(PAR), the variation of TSS with chlorophyll at constant Kd(PAR) determined by the more mechanistic attenuation model was, nevertheless, highly linear. Use of the management tool based on intersecting lines is still possible, but coefficients in the line describing the dependence of TSS on chlorophyll at constant Kd(PAR) must be determined empirically by application of an optical model suitably calibrated for the region of interest. An example application of the procedure to data from the Rhode River, Maryland, indicates that approximately 15% reduction in both TSS and chlorophyll concentrations, or 50% reduction in chlorophyll alone, will be needed to restore conditions for growth of SAV to levels that existed in the late 1960s.\n
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\n \n\n \n \n \n \n \n \n An Examination of Potential Conflict between SAV and Hard Clam Aquaculture in the Lower Chesapeake Bay.\n \n \n \n \n\n\n \n Woods, H.\n\n\n \n\n\n\n Dissertations, Theses, and Masters Projects. January 2001.\n \n\n\n\n
\n\n\n\n \n \n \"AnPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{woods_examination_2001,\n\ttitle = {An {Examination} of {Potential} {Conflict} between {SAV} and {Hard} {Clam} {Aquaculture} in the {Lower} {Chesapeake} {Bay}},\n\turl = {https://scholarworks.wm.edu/etd/1539617771},\n\tdoi = {https://dx.doi.org/doi:10.25773/v5-p1g2-bh33},\n\tjournal = {Dissertations, Theses, and Masters Projects},\n\tauthor = {Woods, Helen},\n\tmonth = jan,\n\tyear = {2001},\n\tkeywords = {Restoration and Management},\n}\n\n
\n
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\n \n\n \n \n \n \n \n \n Ecological dispersal mechanisms, reproductive ecology, and the importance of scale in Zostera marina in Chesapeake Bay.\n \n \n \n \n\n\n \n Harwell, M.\n\n\n \n\n\n\n Dissertations, Theses, and Masters Projects. January 2000.\n \n\n\n\n
\n\n\n\n \n \n \"EcologicalPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{harwell_ecological_2000,\n\ttitle = {Ecological dispersal mechanisms, reproductive ecology, and the importance of scale in {Zostera} marina in {Chesapeake} {Bay}},\n\turl = {https://scholarworks.wm.edu/etd/1539616688},\n\tdoi = {https://dx.doi.org/doi:10.25773/v5-pqte-vy53},\n\tjournal = {Dissertations, Theses, and Masters Projects},\n\tauthor = {Harwell, Matthew},\n\tmonth = jan,\n\tyear = {2000},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n \n\n \n \n \n \n \n \n Eelgrass (Zostera marina L.) seed protection for field experiments and implications for large-scale restoration.\n \n \n \n \n\n\n \n Harwell, M. C; and Orth, R. J\n\n\n \n\n\n\n Aquatic Botany, 64(1): 51–61. May 1999.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"EelgrassPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{harwell_eelgrass_1999,\n\ttitle = {Eelgrass ({Zostera} marina {L}.) seed protection for field experiments and implications for large-scale restoration},\n\tvolume = {64},\n\tissn = {0304-3770},\n\turl = {http://www.sciencedirect.com/science/article/pii/S030437709900008X},\n\tdoi = {10.1016/S0304-3770(99)00008-X},\n\tabstract = {Eelgrass (Zostera marina L.) restoration efforts have historically focused on the use of adult vegetative shoots because of generally low success using seeds, a propagule of potential, but little-known utility, in restoration work. Previous work has shown that approximately 15\\% of seeds broadcast on unvegetated sediments survive to seedling stage, with losses in part resulting from predation, burial, or lateral transport. We conducted experiments using seeds in burlap bags under both laboratory and field settings to determine if protecting seeds increased survival or germination rates. Retention of seeds from preparation to initial sampling six months later was nearly 100\\%. Seedling survival at the field sites ranged from 41 to 56\\% in the burlap bag treatment, compared to 5–15\\% for seeds without burlap bag protection. Under laboratory conditions, seedling survival was identical in both treatments (50\\%). However, successful seedling growth noted in the protected treatment after 6 months was lost by 8 months because of significant sand accumulation over anchored seed bags. These preliminary results are encouraging for future restoration efforts that shift the focus to the use of seeds rather than adult plants, as greater survival of seeds in a protected environment can offer enhanced opportunities for addressing both basic and applied questions in restoration ecology.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Aquatic Botany},\n\tauthor = {Harwell, Matthew C and Orth, Robert J},\n\tmonth = may,\n\tyear = {1999},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {51--61},\n}\n\n
\n
\n\n\n
\n Eelgrass (Zostera marina L.) restoration efforts have historically focused on the use of adult vegetative shoots because of generally low success using seeds, a propagule of potential, but little-known utility, in restoration work. Previous work has shown that approximately 15% of seeds broadcast on unvegetated sediments survive to seedling stage, with losses in part resulting from predation, burial, or lateral transport. We conducted experiments using seeds in burlap bags under both laboratory and field settings to determine if protecting seeds increased survival or germination rates. Retention of seeds from preparation to initial sampling six months later was nearly 100%. Seedling survival at the field sites ranged from 41 to 56% in the burlap bag treatment, compared to 5–15% for seeds without burlap bag protection. Under laboratory conditions, seedling survival was identical in both treatments (50%). However, successful seedling growth noted in the protected treatment after 6 months was lost by 8 months because of significant sand accumulation over anchored seed bags. These preliminary results are encouraging for future restoration efforts that shift the focus to the use of seeds rather than adult plants, as greater survival of seeds in a protected environment can offer enhanced opportunities for addressing both basic and applied questions in restoration ecology.\n
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\n \n\n \n \n \n \n \n \n A rapid and simple method for transplanting eelgrass using single, unanchored shoots.\n \n \n \n \n\n\n \n Orth, R. J; Harwell, M. C; and Fishman, J. R\n\n\n \n\n\n\n Aquatic Botany, 64(1): 77–85. May 1999.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"APaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{orth_rapid_1999,\n\ttitle = {A rapid and simple method for transplanting eelgrass using single, unanchored shoots},\n\tvolume = {64},\n\tissn = {0304-3770},\n\turl = {http://www.sciencedirect.com/science/article/pii/S0304377099000078},\n\tdoi = {10.1016/S0304-3770(99)00007-8},\n\tabstract = {In a large-scale eelgrass (Zostera marina L.) restoration program that began in 1996 in Chesapeake Bay, a simple transplant technique was developed where single, unanchored shoots with rhizomes were planted by hand into the sediment at an angle to a depth of between 25 and 50mm, allowing the more compact area of the sediment above the rhizome to assist in anchoring the plant. This method led to high success, as determined primarily by percent cover and shoot density at four transplant sites in two river systems, where 53 760 shoots were planted into 768 2×2m2 plots. The estimated total time to plant a single shoot using this method, including collection and sorting of shoots for planting, was ≈21s. Survivorship in the first month was high (73\\%) and compares favorably with methodologies from other published studies. Percent cover increased rapidly from 12.3\\% to 18.0\\% over the first eight months to 24.2–38.9\\% after 20 months. Vegetative growth from a single shoot was rapid, with shoot densities similar to those of nearby, natural beds attained in one year or less (e.g., transplanted areas at eight months: 772±203 to 1234±419 shootsm−2; natural areas: 697±256 shootsm−2). Despite the simplicity of this technique, it is fairly robust and complements the recent development of another simple technique (Davis and Short, 1997Aquat. Bot. 59, 1–15) with applications for other seagrass species.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Aquatic Botany},\n\tauthor = {Orth, Robert J and Harwell, Matthew C and Fishman, James R},\n\tmonth = may,\n\tyear = {1999},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {77--85},\n}\n\n
\n
\n\n\n
\n In a large-scale eelgrass (Zostera marina L.) restoration program that began in 1996 in Chesapeake Bay, a simple transplant technique was developed where single, unanchored shoots with rhizomes were planted by hand into the sediment at an angle to a depth of between 25 and 50mm, allowing the more compact area of the sediment above the rhizome to assist in anchoring the plant. This method led to high success, as determined primarily by percent cover and shoot density at four transplant sites in two river systems, where 53 760 shoots were planted into 768 2×2m2 plots. The estimated total time to plant a single shoot using this method, including collection and sorting of shoots for planting, was ≈21s. Survivorship in the first month was high (73%) and compares favorably with methodologies from other published studies. Percent cover increased rapidly from 12.3% to 18.0% over the first eight months to 24.2–38.9% after 20 months. Vegetative growth from a single shoot was rapid, with shoot densities similar to those of nearby, natural beds attained in one year or less (e.g., transplanted areas at eight months: 772±203 to 1234±419 shootsm−2; natural areas: 697±256 shootsm−2). Despite the simplicity of this technique, it is fairly robust and complements the recent development of another simple technique (Davis and Short, 1997Aquat. Bot. 59, 1–15) with applications for other seagrass species.\n
\n\n\n
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\n \n\n \n \n \n \n \n \n Genetic diversity and structure of natural and transplanted eelgrass populations in the Chesapeake and Chincoteague Bays.\n \n \n \n \n\n\n \n Williams, S. L.; and Orth, R. J.\n\n\n \n\n\n\n Estuaries, 21(1): 118–128. March 1998.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"GeneticPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{williams_genetic_1998,\n\ttitle = {Genetic diversity and structure of natural and transplanted eelgrass populations in the {Chesapeake} and {Chincoteague} {Bays}},\n\tvolume = {21},\n\tissn = {0160-8347},\n\turl = {https://doi.org/10.2307/1352551},\n\tdoi = {10.2307/1352551},\n\tabstract = {The objective of this study was to gain baseline population data on the genetic diversity and differentiation of eelgrass (Zostera marïna L.) populations in the Chesapeake and Chincoteague bays. Natural and transplanted eelgrass beds were compared using starch gel electrophoresis of allozymes. Transplanted eelgrass beds were not reduced in genetic diversity compared with natural beds. Inbreeding coefficients (FIS) indicated that transplanted eelgrass beds had theoretically higher levels of outcrossing than natural beds, suggesting the significance of use of seeds as donor material and of seedling recruitment following transplantation diebacks. Natural populations exhibited very great genetic structure (FST=0.335), but transplanted beds were genetically similar to the donor bed and each other. Genetic diversity was lowest in Chincoteague Bay, reflecting recent restoration history since the 1930s wasting disease and geographical isolation from other east coast populations. These data provide a basis for developing a management plan for conserving eelgrass genetic diversity in the Chesapeake Bay and for guiding estuary-wide restoration efforts. It will be important to recognize that the natural genetic diversity of eelgrass in the estuary is distributed among various populations and is not well represented by single populations.},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Estuaries},\n\tauthor = {Williams, Susan L. and Orth, Robert J.},\n\tmonth = mar,\n\tyear = {1998},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {118--128},\n}\n\n
\n
\n\n\n
\n The objective of this study was to gain baseline population data on the genetic diversity and differentiation of eelgrass (Zostera marïna L.) populations in the Chesapeake and Chincoteague bays. Natural and transplanted eelgrass beds were compared using starch gel electrophoresis of allozymes. Transplanted eelgrass beds were not reduced in genetic diversity compared with natural beds. Inbreeding coefficients (FIS) indicated that transplanted eelgrass beds had theoretically higher levels of outcrossing than natural beds, suggesting the significance of use of seeds as donor material and of seedling recruitment following transplantation diebacks. Natural populations exhibited very great genetic structure (FST=0.335), but transplanted beds were genetically similar to the donor bed and each other. Genetic diversity was lowest in Chincoteague Bay, reflecting recent restoration history since the 1930s wasting disease and geographical isolation from other east coast populations. These data provide a basis for developing a management plan for conserving eelgrass genetic diversity in the Chesapeake Bay and for guiding estuary-wide restoration efforts. It will be important to recognize that the natural genetic diversity of eelgrass in the estuary is distributed among various populations and is not well represented by single populations.\n
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\n \n\n \n \n \n \n \n \n Invasions and Declines of Submersed Macrophytes in the Tidal Potomac River and Estuary, the Currituck Sound-Back Bay System, and the Pamlico River Estuary.\n \n \n \n \n\n\n \n Carter, V.; and Rybicki, N. B.\n\n\n \n\n\n\n Lake and Reservoir Management, 10(1): 39–48. November 1994.\n Number: 1 Publisher: Taylor & Francis _eprint: https://doi.org/10.1080/07438149409354171\n\n\n\n
\n\n\n\n \n \n \"InvasionsPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
\n 
@article{carter_invasions_1994,\n\ttitle = {Invasions and {Declines} of {Submersed} {Macrophytes} in the {Tidal} {Potomac} {River} and {Estuary}, the {Currituck} {Sound}-{Back} {Bay} {System}, and the {Pamlico} {River} {Estuary}},\n\tvolume = {10},\n\tissn = {1040-2381},\n\turl = {https://doi.org/10.1080/07438149409354171},\n\tdoi = {10.1080/07438149409354171},\n\tabstract = {Long-term changes in biomass, species composition, and distribution of submersed aquatic macrophytes have been documented and studied at two sites in the mid-Atlantic region: the tidal Potomac River and Estuary in Maryland, Virginia, and the District of Columbia, and the Currituck Sound-Back Bay system in Virginia and North Carolina. Additional information based on a shorter time period is available for the Pamlico River Estuary in North Carolina. This paper briefly describes the study areas and summaries the history of declines and increases in each area and factors implicated in these changes. The remainder of the paper is devoted to a discussion of factors influencing invasion/establishment success and the current status of submersed macrophytes in the three areas.},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Lake and Reservoir Management},\n\tauthor = {Carter, Virginia and Rybicki, N. B.},\n\tmonth = nov,\n\tyear = {1994},\n\tnote = {Number: 1\nPublisher: Taylor \\& Francis\n\\_eprint: https://doi.org/10.1080/07438149409354171},\n\tkeywords = {Restoration and Management},\n\tpages = {39--48},\n}\n\n
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\n Long-term changes in biomass, species composition, and distribution of submersed aquatic macrophytes have been documented and studied at two sites in the mid-Atlantic region: the tidal Potomac River and Estuary in Maryland, Virginia, and the District of Columbia, and the Currituck Sound-Back Bay system in Virginia and North Carolina. Additional information based on a shorter time period is available for the Pamlico River Estuary in North Carolina. This paper briefly describes the study areas and summaries the history of declines and increases in each area and factors implicated in these changes. The remainder of the paper is devoted to a discussion of factors influencing invasion/establishment success and the current status of submersed macrophytes in the three areas.\n
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\n \n\n \n \n \n \n \n \n Chesapeake Bay Submersed Aquatic Vegetation: Water Quality Relationships.\n \n \n \n \n\n\n \n Orth, R. J.\n\n\n \n\n\n\n Lake and Reservoir Management, 10(1): 49–52. November 1994.\n Number: 1\n\n\n\n
\n\n\n\n \n \n \"ChesapeakePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_chesapeake_1994,\n\ttitle = {Chesapeake {Bay} {Submersed} {Aquatic} {Vegetation}: {Water} {Quality} {Relationships}},\n\tvolume = {10},\n\tissn = {1040-2381, 2151-5530},\n\tshorttitle = {Chesapeake {Bay} {Submersed} {Aquatic} {Vegetation}},\n\turl = {http://www.tandfonline.com/doi/abs/10.1080/07438149409354172},\n\tdoi = {10.1080/07438149409354172},\n\tlanguage = {en},\n\tnumber = {1},\n\turldate = {2020-05-13},\n\tjournal = {Lake and Reservoir Management},\n\tauthor = {Orth, Robert J.},\n\tmonth = nov,\n\tyear = {1994},\n\tnote = {Number: 1},\n\tkeywords = {Restoration and Management},\n\tpages = {49--52},\n}\n\n
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\n \n\n \n \n \n \n \n Seed dispersal in a marine macrophyte: Implications for colonization and restoration.\n \n \n \n\n\n \n Orth, R. J.; Luckenbach, M.; and Moore, K. A.\n\n\n \n\n\n\n Ecology. 1994.\n \n\n\n\n
\n\n\n\n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{orth_seed_1994,\n\ttitle = {Seed dispersal in a marine macrophyte: {Implications} for colonization and restoration},\n\tdoi = {10.2307/1941597},\n\tjournal = {Ecology},\n\tauthor = {Orth, R. J. and Luckenbach, M. and Moore, K. A.},\n\tyear = {1994},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n \n\n \n \n \n \n \n \n Chesapeake bay submerged aquatic vegetation habitat requirements and restoration targets: A technical synthesis.\n \n \n \n \n\n\n \n Batiuk, R. A.; Orth, R. J.; Moore, K. A.; Dennison, W. C.; and Stevenson, J. C.\n\n\n \n\n\n\n Technical Report PB-93-196665/XAB, Virginia Institute of Marine Science, Gloucester Point, VA (United States), December 1992.\n \n\n\n\n
\n\n\n\n \n \n \"ChesapeakePaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@techreport{batiuk_chesapeake_1992,\n\ttitle = {Chesapeake bay submerged aquatic vegetation habitat requirements and restoration targets: {A} technical synthesis},\n\tshorttitle = {Chesapeake bay submerged aquatic vegetation habitat requirements and restoration targets},\n\turl = {https://www.osti.gov/biblio/6084380},\n\tabstract = {The U.S. Department of Energy's Office of Scientific and Technical Information},\n\tlanguage = {English},\n\tnumber = {PB-93-196665/XAB},\n\turldate = {2020-05-15},\n\tinstitution = {Virginia Institute of Marine Science, Gloucester Point, VA (United States)},\n\tauthor = {Batiuk, R. A. and Orth, R. J. and Moore, K. A. and Dennison, W. C. and Stevenson, J. C.},\n\tmonth = dec,\n\tyear = {1992},\n\tkeywords = {Restoration and Management},\n}\n\n
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\n The U.S. Department of Energy's Office of Scientific and Technical Information\n
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\n \n\n \n \n \n \n \n \n The effects of grazers and light penetration on the survival of transplants of Vallisneria americana Michs in the tidal Potomac River, Maryland.\n \n \n \n \n\n\n \n Carter, V.; and Rybicki, N. B.\n\n\n \n\n\n\n Aquatic Botany, 23(3): 197–213. December 1985.\n \n\n\n\n
\n\n\n\n \n \n \"ThePaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{carter_effects_1985,\n\ttitle = {The effects of grazers and light penetration on the survival of transplants of {Vallisneria} americana {Michs} in the tidal {Potomac} {River}, {Maryland}},\n\tvolume = {23},\n\tissn = {0304-3770},\n\turl = {http://www.sciencedirect.com/science/article/pii/030437708590066X},\n\tdoi = {10.1016/0304-3770(85)90066-X},\n\tabstract = {Poor light penetration and grazing are among the factors potentially responsible for the lack of submersed aquatic macrophytes in the tidal Potomac River. Between 1980 and 1983, plugs, springs and tubers of Vallisneria americana Michx were transplanted from the oligohaline Potomac Estuary to six sites in the freshwater tidal Potomac River. Transplants made in 1980 and 1981 were generally successful only when protected by full exclosures which prevented grazing. Grazing resulted in the removal of whole plants or clipping off of plant leaves in unprotected plots. Plants protected in the first year were permanently established, despite the occurrence of grazing in subsequent years, at Elodea Cove and Rosier Bluff, where light penetration was high (average 1\\% light level was 1.6–1.7 m). Plants were not permanent;y established at Goose Island, where light penetration was lower (average 1\\% light level was 1.4 m) and grazing occurred, or Neabsco Bay where light penetration was very low (average 1\\% light level was 1.0 m) and grazing may not have occurred. In 1983, Secchi depth transparencies in the upper tidal river were improved significantly compared to 1978–1981. Both protected and unprotected transplants thrived in 1983.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-05-15},\n\tjournal = {Aquatic Botany},\n\tauthor = {Carter, Virginia and Rybicki, Nancy B.},\n\tmonth = dec,\n\tyear = {1985},\n\tkeywords = {Restoration and Management},\n\tpages = {197--213},\n}\n\n
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\n Poor light penetration and grazing are among the factors potentially responsible for the lack of submersed aquatic macrophytes in the tidal Potomac River. Between 1980 and 1983, plugs, springs and tubers of Vallisneria americana Michx were transplanted from the oligohaline Potomac Estuary to six sites in the freshwater tidal Potomac River. Transplants made in 1980 and 1981 were generally successful only when protected by full exclosures which prevented grazing. Grazing resulted in the removal of whole plants or clipping off of plant leaves in unprotected plots. Plants protected in the first year were permanently established, despite the occurrence of grazing in subsequent years, at Elodea Cove and Rosier Bluff, where light penetration was high (average 1% light level was 1.6–1.7 m). Plants were not permanent;y established at Goose Island, where light penetration was lower (average 1% light level was 1.4 m) and grazing occurred, or Neabsco Bay where light penetration was very low (average 1% light level was 1.0 m) and grazing may not have occurred. In 1983, Secchi depth transparencies in the upper tidal river were improved significantly compared to 1978–1981. Both protected and unprotected transplants thrived in 1983.\n
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\n \n\n \n \n \n \n \n \n Economic losses associated with the degradation of an ecosystem: The case of submerged aquatic vegetation in Chesapeake Bay.\n \n \n \n \n\n\n \n Kahn, J. R; and Kemp, W. M.\n\n\n \n\n\n\n Journal of Environmental Economics and Management, 12(3): 246–263. September 1985.\n \n\n\n\n
\n\n\n\n \n \n \"EconomicPaper\n  \n \n\n \n \n doi\n  \n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@article{kahn_economic_1985,\n\ttitle = {Economic losses associated with the degradation of an ecosystem: {The} case of submerged aquatic vegetation in {Chesapeake} {Bay}},\n\tvolume = {12},\n\tissn = {0095-0696},\n\tshorttitle = {Economic losses associated with the degradation of an ecosystem},\n\turl = {http://www.sciencedirect.com/science/article/pii/0095069685900336},\n\tdoi = {10.1016/0095-0696(85)90033-6},\n\tabstract = {This study employs theoretical and empirical concepts from ecology and economics to derive a lower bound of the marginal damage function for reductions in the level of submerged aquatic vegetation (SAV) in Chesapeake Bay. These reductions in SAV are believed to be a consequence of the runoff of agricultural chemicals, discharges from waste treatment plants, and soil erosion. The study examines the indirect ecological consequences of pollution in Chesapeak Bay fisheries, in a fashion which is consistent with the economic theory of benefit measurement.},\n\tlanguage = {en},\n\tnumber = {3},\n\turldate = {2020-05-15},\n\tjournal = {Journal of Environmental Economics and Management},\n\tauthor = {Kahn, James R and Kemp, W. Michael},\n\tmonth = sep,\n\tyear = {1985},\n\tkeywords = {Restoration and Management},\n\tpages = {246--263},\n}\n\n
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\n This study employs theoretical and empirical concepts from ecology and economics to derive a lower bound of the marginal damage function for reductions in the level of submerged aquatic vegetation (SAV) in Chesapeake Bay. These reductions in SAV are believed to be a consequence of the runoff of agricultural chemicals, discharges from waste treatment plants, and soil erosion. The study examines the indirect ecological consequences of pollution in Chesapeak Bay fisheries, in a fashion which is consistent with the economic theory of benefit measurement.\n
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\n \n\n \n \n \n \n \n \n SAV Reestablishment Results—Upper Chesapeake Bay.\n \n \n \n \n\n\n \n Kollar, S. A.\n\n\n \n\n\n\n In pages 759–777, 1985. ASCE\n \n\n\n\n
\n\n\n\n \n \n \"SAVPaper\n  \n \n\n \n\n \n link\n  \n \n\n bibtex\n \n\n \n  \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n  \n \n \n \n \n\n\n\n
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@inproceedings{kollar_sav_1985,\n\ttitle = {{SAV} {Reestablishment} {Results}—{Upper} {Chesapeake} {Bay}},\n\turl = {https://cedb.asce.org/CEDBsearch/record.jsp?dockey=0044236},\n\tabstract = {{\\textless}p{\\textgreater}In the Susquehanna Flats area of the upper Chesapeake Bay, six submersed aquatic plant species were used to test the feasibility of transplanting SAV into sites which were previously vegetated, but currently lacking or minimally populated by submersed macrophytes. Transplant success was found to be positively correlated with depths of 2. 5 ft. to 3. 5 ft. mean tidal depth, sediments of at least 21\\% silt, and some form of sheltering influence. Negative factors appeared to be high current velocity, water depths outside of the indicated positive range, substrates of high sand content and grazing pressure.{\\textless}/p{\\textgreater}},\n\tlanguage = {eng},\n\turldate = {2020-05-15},\n\tpublisher = {ASCE},\n\tauthor = {Kollar, Stanley A.},\n\tyear = {1985},\n\tkeywords = {Restoration and Management},\n\tpages = {759--777},\n}\n\n
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\n \\textlessp\\textgreaterIn the Susquehanna Flats area of the upper Chesapeake Bay, six submersed aquatic plant species were used to test the feasibility of transplanting SAV into sites which were previously vegetated, but currently lacking or minimally populated by submersed macrophytes. Transplant success was found to be positively correlated with depths of 2. 5 ft. to 3. 5 ft. mean tidal depth, sediments of at least 21% silt, and some form of sheltering influence. Negative factors appeared to be high current velocity, water depths outside of the indicated positive range, substrates of high sand content and grazing pressure.\\textless/p\\textgreater\n
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@misc{noauthor_document_nodate,\n\ttitle = {Document {Display} {\\textbar} {NEPIS} {\\textbar} {US} {EPA}},\n\turl = {https://nepis.epa.gov/Exe/ZyNET.exe/910177AX.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1991+Thru+1994&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C91thru94%5CTxt%5C00000028%5C910177AX.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL},\n\tlanguage = {en},\n\turldate = {2020-06-05},\n\tnote = {Library Catalog: nepis.epa.gov},\n}\n\n
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