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\n\n \n \n \n \n \n The influence of dissolved organic matter (DOM) on sodium regulation and nitrogenous waste excretion in the zebrafish (Danio rerio).\n \n \n \n\n\n \n Al-Reasi, H.; Smith, D. S.; and Wood, C. M.\n\n\n \n\n\n\n
Journal of Experimental Biology, 219: 2289�2299. 2016.\n
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@article{Al-Reasietal:2016,\n\tauthor = {Al-Reasi, H. and Smith, D. Scott and Wood, C. M.},\n\tdoi = {10.1242/jeb.139444},\n\tjournal = {Journal of Experimental Biology},\n\towner = {ssmith},\n\tpages = {2289�2299},\n\ttimestamp = {2015.08.10},\n\ttitle = {The influence of dissolved organic matter (DOM) on sodium regulation and nitrogenous waste excretion in the zebrafish (<i>Danio rerio</i>)},\n\tvolume = {219},\n\tyear = {2016}\n}\n\n
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\n\n \n \n \n \n \n Mechanisms of nickel toxicity in the highly sensitive embryos of the sea urchin Evechinus chloroticus, and the modifying effects of dissolved organic carbon.\n \n \n \n\n\n \n Blewett, T. A.; Smith, D. S.; Wood, C. M.; and Glover, C. N.\n\n\n \n\n\n\n
Environmental Science & Technology, 50: 1595�1603. 2016.\n
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@article{Blewettetal:2016,\n\tabstract = {A 96 h toxicity test showed that the embryos of the New Zealand sea urchin (Evechinus chloroticus) are the most sensitive of all studied marine species to waterborne nickel (Ni), with the EC50 for the development of fully formed pluteus larvae found to be 14 ug L^-1. Failure to develop a standard larval shape suggested skeletal impairment. Whole body ions (Na, Mg) increased with Ni exposure and calcium influx was depressed. The effects of natural organic matter (NOM) on Ni accumulation and toxicity were also examined in three different seawater sources (nearshore, offshore, and near the outlet of a “brown water�? stream). At low dissolved organic carbon (DOC) concentrations the brown water NOM was protective against Ni toxicity, however at higher DOC concentrations it exacerbated developmental toxicity in the presence of Ni. These results show that sea urchin development is highly sensitive to Ni via a mechanism that involves ionoregulatory disturbance, and that Ni toxicity is influenced by environmental factors such as NOM. These data will be critical for the development of water quality guidelines for Ni in the marine environment.},\n\tauthor = {Blewett, T. A. and Smith, D. S. and Wood, C. M. and Glover, C. N.},\n\tdoi = {10.1021/acs.est.5b05626},\n\tjournal = {Environmental Science \\& Technology},\n\towner = {ssmith},\n\tpages = {1595�1603},\n\ttimestamp = {2015.04.13},\n\ttitle = {Mechanisms of nickel toxicity in the highly sensitive embryos of the sea urchin <i>Evechinus chloroticus</i>, and the modifying effects of dissolved organic carbon},\n\tvolume = {50},\n\tyear = {2016}\n}\n\n
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\n A 96 h toxicity test showed that the embryos of the New Zealand sea urchin (Evechinus chloroticus) are the most sensitive of all studied marine species to waterborne nickel (Ni), with the EC50 for the development of fully formed pluteus larvae found to be 14 ug L^-1. Failure to develop a standard larval shape suggested skeletal impairment. Whole body ions (Na, Mg) increased with Ni exposure and calcium influx was depressed. The effects of natural organic matter (NOM) on Ni accumulation and toxicity were also examined in three different seawater sources (nearshore, offshore, and near the outlet of a “brown water�? stream). At low dissolved organic carbon (DOC) concentrations the brown water NOM was protective against Ni toxicity, however at higher DOC concentrations it exacerbated developmental toxicity in the presence of Ni. These results show that sea urchin development is highly sensitive to Ni via a mechanism that involves ionoregulatory disturbance, and that Ni toxicity is influenced by environmental factors such as NOM. These data will be critical for the development of water quality guidelines for Ni in the marine environment.\n
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\n\n \n \n \n \n \n Investigating copper toxicity in the tropical fish cardinal tetra (Paracheirodon axelrodi) in natural Amazonian waters: measurements, modeling, and reality.\n \n \n \n\n\n \n Cremazy, A.; Wood, C. M.; Smith, D. S.; Ferreira, M. S.; Johannsson, O. E.; Giacomin, M. M.; and Val, A. L.\n\n\n \n\n\n\n
Aquatic Tox., 180: 353�363. 2016.\n
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@article{Cremazyetal:2016,\n\tauthor = {Cremazy, A. and Wood, C. M. and Smith, D. S. and Ferreira, M. S. and Johannsson, O. E. and Giacomin, M. M. and Val, A. L.},\n\tdoi = {10.1016/j.aquatox.2016.10.011},\n\tjournal = {Aquatic Tox.},\n\tjournaltitle = {Aquatic Toxicology},\n\tpages = {353�363},\n\ttitle = {Investigating copper toxicity in the tropical fish cardinal tetra (<i>Paracheirodon axelrodi</i>) in natural Amazonian waters: measurements, modeling, and reality},\n\tvolume = {180},\n\tyear = {2016}\n}\n\n
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\n\n \n \n \n \n \n \n Dissolved organic carbon (DOC) from the upper Rio Negro protects zebrafish (Danio rerio) against ionoregulatory disturbances caused by low pH exposure.\n \n \n \n \n\n\n \n Duarte, R.; Smith, D. S.; Val, A.; and Wood, C.\n\n\n \n\n\n\n
Scientific Reports, 6: 20377. 2016.\n
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@article{Duarteetal:2016,\n\tabstract = {The so-called “blackwaters�? of the Amazonian Rio Negro are rich in highly coloured dissolved organic carbon (DOC), but ion-poor and very acidic, conditions that would cause fatal ionoregulatory failure in most fish. However these blackwaters support 8\\% of the world’s ichthyofauna. We tested the hypothesis that native DOC provides protection against ionoregulatory dysfunction in this extreme environment. DOCs were isolated by reverse-osmosis from two Rio Negro sites. Physico-chemical characterization clearly indicated a terrigenous origin, with a high proportion of hydroxyl and phenolic sites, high chemical reactivity to protons, and unusual proteinaceous fluorescence. When tested using zebrafish (a model organism), Rio Negro DOC provided almost perfect protection against ionoregulatory disturbances associated with acute exposure to pH 4.0 in ion-poor water. DOC reduced diffusive losses of Na+ and Cl�-, and promoted a remarkable stimulation of Na+ uptake that otherwise would have been completely inhibited. Additionally, prior acclimation to DOC at neutral pH reduced rates of branchial Na+ turnover, and provided similar protection against acid-induced ionoregulatory disturbances, even if the DOC was no longer present. These results reinforce the important roles that DOC molecules can play in the regulation of gill functions in freshwater fish, particularly in ion-poor, acidic blackwaters.},\n\tauthor = {Duarte, Rafael and Smith, D. S. and Val, Adalberto and Wood, Christopher},\n\tdoi = {10.1038/srep20377},\n\tjournal = {Scientific Reports},\n\towner = {ssmith},\n\tpages = {20377},\n\ttimestamp = {2015.07.16},\n\ttitle = {Dissolved organic carbon ({DOC}) from the upper Rio Negro protects zebrafish (<i>Danio rerio</i>) against ionoregulatory disturbances caused by low {pH} exposure},\n\turl = {http://clearlab.synology.me/publications/Duarteetal2016.pdf},\n\tvolume = {6},\n\tyear = {2016}\n}\n\n
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\n The so-called “blackwaters�? of the Amazonian Rio Negro are rich in highly coloured dissolved organic carbon (DOC), but ion-poor and very acidic, conditions that would cause fatal ionoregulatory failure in most fish. However these blackwaters support 8% of the world’s ichthyofauna. We tested the hypothesis that native DOC provides protection against ionoregulatory dysfunction in this extreme environment. DOCs were isolated by reverse-osmosis from two Rio Negro sites. Physico-chemical characterization clearly indicated a terrigenous origin, with a high proportion of hydroxyl and phenolic sites, high chemical reactivity to protons, and unusual proteinaceous fluorescence. When tested using zebrafish (a model organism), Rio Negro DOC provided almost perfect protection against ionoregulatory disturbances associated with acute exposure to pH 4.0 in ion-poor water. DOC reduced diffusive losses of Na+ and Cl�-, and promoted a remarkable stimulation of Na+ uptake that otherwise would have been completely inhibited. Additionally, prior acclimation to DOC at neutral pH reduced rates of branchial Na+ turnover, and provided similar protection against acid-induced ionoregulatory disturbances, even if the DOC was no longer present. These results reinforce the important roles that DOC molecules can play in the regulation of gill functions in freshwater fish, particularly in ion-poor, acidic blackwaters.\n
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\n\n \n \n \n \n \n Properties of Dissolved Organic Carbon, Reactive Oxygen Species (H2O2) Concentration and their Impact on a Native Fish, Hemigrammus levis in the Anavilhanas Archipelago, Rio Negro, Amazonia, Brazil.\n \n \n \n\n\n \n Johannsson, O. E.; Smith, D. S.; Sadauskas-Henrique, H.; Cameron, G.; Wood, C. M.; and Val, A. L.\n\n\n \n\n\n\n
Hydrobiologia, 789(1): 7�29. 2016.\n
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@article{Johannssonetal:2016,\n\tabstract = {Given the reported degraded nature of DOC in the Rio Negro, and low oxygen, pH, and bacterial riverine levels, we hypothesized: (1) DOC would have strong humic and fulvic acid fluorescence signals with high aromaticity and large mean molecular weight; and (2) photo-oxidation rates would be slow, and reactive oxygen species (ROS) concentrations low, producing no oxidative stress in biota. We surveyed the environment and properties of DOC and explored DOC photo-oxidation and fish sensitivity to DOC products. DOC properties were investigated using absorption and fluorescence indices and parallel factor analysis (PARAFAC) of excitation–emission matrices. ROS concentrations were measured spectrophotometrically. A native fish, Hemigrammus levis, was exposed to photo-oxidizing DOC and its tissues (brain, gill, liver) assayed for changes in antioxidant and biotransformation enzymes. With respect to our hypotheses, (1) DOC was highly terrigenous, with high SAC340 values (aromaticity), high capacity to produce ROS, and high tryptophan-like fluorescence (bacterial, autochthonous signal); (2) photo-oxidation rates were appreciable, while products were related to mean UV-radiation levels (total radiation was constant). ROS levels were often higher than freshwater averages, yet fish experienced no oxidative stress. Results suggest photo-oxidation influences patterns in C-cycling, bacterial production and community dynamics between wet and dry seasons.},\n\tauthor = {Johannsson, Ora E. and Smith, D. Scott and Sadauskas-Henrique, H. and Cameron, G. and Wood, C. M. and Val, Adalberto L.},\n\tdoi = {10.1007/s10750-016-2687-9},\n\tjournal = {Hydrobiologia},\n\tnumber = {1},\n\towner = {ssmith},\n\tpages = {7�29},\n\ttimestamp = {2015.07.16},\n\ttitle = {Properties of Dissolved Organic Carbon, Reactive Oxygen Species ({H}<sub>2</sub>{O}<sub>2</sub>) Concentration and their Impact on a Native Fish, <i>Hemigrammus levis</i> in the {Anavilhanas Archipelago, Rio Negro, Amazonia, Brazil}},\n\tvolume = {789},\n\tyear = {2016}\n}\n\n
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\n Given the reported degraded nature of DOC in the Rio Negro, and low oxygen, pH, and bacterial riverine levels, we hypothesized: (1) DOC would have strong humic and fulvic acid fluorescence signals with high aromaticity and large mean molecular weight; and (2) photo-oxidation rates would be slow, and reactive oxygen species (ROS) concentrations low, producing no oxidative stress in biota. We surveyed the environment and properties of DOC and explored DOC photo-oxidation and fish sensitivity to DOC products. DOC properties were investigated using absorption and fluorescence indices and parallel factor analysis (PARAFAC) of excitation–emission matrices. ROS concentrations were measured spectrophotometrically. A native fish, Hemigrammus levis, was exposed to photo-oxidizing DOC and its tissues (brain, gill, liver) assayed for changes in antioxidant and biotransformation enzymes. With respect to our hypotheses, (1) DOC was highly terrigenous, with high SAC340 values (aromaticity), high capacity to produce ROS, and high tryptophan-like fluorescence (bacterial, autochthonous signal); (2) photo-oxidation rates were appreciable, while products were related to mean UV-radiation levels (total radiation was constant). ROS levels were often higher than freshwater averages, yet fish experienced no oxidative stress. Results suggest photo-oxidation influences patterns in C-cycling, bacterial production and community dynamics between wet and dry seasons.\n
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\n\n \n \n \n \n \n Influence of Dissolved Organic Matter (DOM) source on copper speciation and toxicity to Brachionus plicatilis.\n \n \n \n\n\n \n Tait, N. T.; Cooper, C. A.; McGeer, J. C.; Wood, C. M.; and Smith, D. S.\n\n\n \n\n\n\n
Env. Chem., 13: 496�506. 2016.\n
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@article{Taitetal:2016,\n\tabstract = {The toxicity of copper in marine systems is dependent on its speciation and bioavailability. Dissolved organic matter (DOM) can complex copper, resulting in decreased bioavailability and hence decreased toxicity. The purpose of this study was to measure acute copper LC50 values (concentration lethal to 50 \\% of the organisms) in natural marine waters in a sensitive organism, and identify the relationships between DOM quality and copper toxicity and speciation. Static acute copper toxicity tests (48-h LC50) were performed using the euryhaline rotifer Brachionus plicatilis. Ion-selective electrode measurements of free copper were performed at the LC50 concentrations to determine the influence of DOM source on copper speciation. LC50 values ranged from 333 to 980 nM (21.1 to 62.3 µg L�-1) with DOC concentrations ranging from 0.55 to 7.57 mg C L�-1. DOC was found to be protective (R2 = 0.72, P = 0.016); however, the degree of protection decreased as DOC increased. This suggests salt-induced colloid formation could be occurring, resulting in a decrease of binding sites available to complex free copper. Free copper remained fairly constant between each sample site, with an average pCu of 10.14. Overall, this study is consistent with other studies that suggest free copper is the best species for predicting toxicity. Additionally, no significant correlation between DOM source and copper toxicity was observed as compared with total DOC concentration and copper toxicity, suggesting that DOM quality does not need to be taken into account for copper toxicity modelling in salt water.},\n\tauthor = {Tait, N. T. and Cooper, C. A. and McGeer, J. C. and Wood, C. M. and Smith, D. S.},\n\tdoi = {10.1071/EN15123},\n\tjournal = {Env. Chem.},\n\towner = {ssmith},\n\tpages = {496�506},\n\ttimestamp = {2015.07.16},\n\ttitle = {Influence of Dissolved Organic Matter (DOM) source on copper speciation and toxicity to <i>Brachionus plicatilis</i>},\n\tvolume = {13},\n\tyear = {2016}\n}\n\n
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\n The toxicity of copper in marine systems is dependent on its speciation and bioavailability. Dissolved organic matter (DOM) can complex copper, resulting in decreased bioavailability and hence decreased toxicity. The purpose of this study was to measure acute copper LC50 values (concentration lethal to 50 % of the organisms) in natural marine waters in a sensitive organism, and identify the relationships between DOM quality and copper toxicity and speciation. Static acute copper toxicity tests (48-h LC50) were performed using the euryhaline rotifer Brachionus plicatilis. Ion-selective electrode measurements of free copper were performed at the LC50 concentrations to determine the influence of DOM source on copper speciation. LC50 values ranged from 333 to 980 nM (21.1 to 62.3 µg L�-1) with DOC concentrations ranging from 0.55 to 7.57 mg C L�-1. DOC was found to be protective (R2 = 0.72, P = 0.016); however, the degree of protection decreased as DOC increased. This suggests salt-induced colloid formation could be occurring, resulting in a decrease of binding sites available to complex free copper. Free copper remained fairly constant between each sample site, with an average pCu of 10.14. Overall, this study is consistent with other studies that suggest free copper is the best species for predicting toxicity. Additionally, no significant correlation between DOM source and copper toxicity was observed as compared with total DOC concentration and copper toxicity, suggesting that DOM quality does not need to be taken into account for copper toxicity modelling in salt water.\n
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\n\n \n \n \n \n \n Acute dysprosium toxicity to Daphnia pulex and Hyalella azteca and development of the biotic ligand approach.\n \n \n \n\n\n \n Vukov, O.; Smith, D. S.; and McGeer, J. C.\n\n\n \n\n\n\n
Aquatic. Tox., 170: 142�151. 2016.\n
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@article{Vukovetal:2016,\n\tabstract = {The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60 mg CaCO3 mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23 °C. Acute toxicity tests were done with <24 h old neonates for 48 h in the case of D. pulex and with 2�-9 days old offspring for 96 h tests with Hyalella. The potential protective effect of cationic competition was tested with Ca (0.5�-2.0 mM), Na (0.5�-2.0 mM) and Mg (0.125�-0.5 mM). The effect of pH (6.5�-8.0) and Suwannee River DOM complexation (at dissolved organic carbon (DOC) concentrations of 9 and 13 mg C/L) were evaluated. Dissolved Dy concentrations were lower than total (unfiltered) indicating precipitation, particularly at higher concentrations. Acute toxicity of Dy to H. azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (Log K values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The log K value for Dy3+ toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific water quality guidelines and criteria for Dy and possibly REEs in general and offers insight into the complex bio-geochemical nature of this element.},\n\tauthor = {Vukov, O. and Smith, D. S. and McGeer, J. C.},\n\tdoi = {10.1016/j.aquatox.2015.10.016},\n\tjournal = {Aquatic. Tox.},\n\towner = {ssmith},\n\tpages = {142�151},\n\ttimestamp = {2015.07.27},\n\ttitle = {Acute dysprosium toxicity to <i>Daphnia pulex</i> and <i>Hyalella azteca</i> and development of the biotic ligand approach.},\n\tvolume = {170},\n\tyear = {2016}\n}\n\n
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\n The toxicological understanding of rare earth elements (REEs) in the aquatic environment is very limited but of increasing concern. The objective of this research is to compare the toxicological effect of the REE dysprosium to the freshwater invertebrates Daphnia pulex and Hyalella azteca and in the more sensitive organism, understand the toxicity modifying influence of Ca, Na, Mg, pH and dissolved organic matter (DOM). Standard methods (Environment Canada) were followed for testing and culture in media of intermediate hardness (60 mg CaCO3 mg/L) at pH 7.8 with Ca at 0.5, Na 0.5, Mg 0.125 (mM) and 23 °C. Acute toxicity tests were done with <24 h old neonates for 48 h in the case of D. pulex and with 2�-9 days old offspring for 96 h tests with Hyalella. The potential protective effect of cationic competition was tested with Ca (0.5�-2.0 mM), Na (0.5�-2.0 mM) and Mg (0.125�-0.5 mM). The effect of pH (6.5�-8.0) and Suwannee River DOM complexation (at dissolved organic carbon (DOC) concentrations of 9 and 13 mg C/L) were evaluated. Dissolved Dy concentrations were lower than total (unfiltered) indicating precipitation, particularly at higher concentrations. Acute toxicity of Dy to H. azteca and D. pulex revealed Hyalella to be 1.4 times more sensitive than Daphnia. Additions of Ca and Na but not Mg provided significant protection against Dy toxicity to Hyalella. Similarly, low pH was associated with reduction in toxicity. Exposures which were pH buffered with and without MOPS were significantly different and indicated that MOPS enhanced Dy toxicity. DOM also mitigated Dy toxicity. Biotic ligand based parameters (Log K values) were calculated based on free ion relationships as determined by geochemical equilibrium modeling software (WHAM ver. 7.02). The log K value for Dy3+ toxicity to Hyalella was 7.75 while the protective influence of Ca and Na were 3.95 and 4.10, respectively. This study contributes data towards the development of site specific water quality guidelines and criteria for Dy and possibly REEs in general and offers insight into the complex bio-geochemical nature of this element.\n
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