Short-term variability and control of phytoplankton photosynthetic activity in a macrotidal ecosystem (the Strait of Dover, eastern English Channel). Houliez, E., Lizon, F., Lefebvre, S., Artigas, L. F., & Schmitt, F. G. 160(7):1661–1679. Number: 7
Short-term variability and control of phytoplankton photosynthetic activity in a macrotidal ecosystem (the Strait of Dover, eastern English Channel) [link]Paper  doi  abstract   bibtex   
Short-term changes in phytoplankton photosynthetic activity were studied during different periods of the years 2009 and 2010 in the coastal waters of a macrotidal ecosystem (the Strait of Dover, eastern English Channel). During each sampling period, samples were taken every 1.45 h., from sunrise to sunset, during at least 5 days distributed along a complete spring–neap tide cycle. The photosynthetic parameters were obtained by measuring rapid light curves using pulse amplitude modulated fluorometry and were related to environmental conditions and phytoplankton taxonomic composition. The maximum quantum yield (F v/F m) showed clear light-dependent changes and could vary from physiological maxima (0.68–0.60) to values close to 0.30 during the course of 1 day, suggesting the operation of photoprotective mechanisms. The maximum electron transport rate (ETRm) and maximal light utilization efficiency (α) were generally positively correlated and showed large diel variability. These parameters fluctuated significantly from hour to hour within each day and the intraday pattern of variation changed significantly among days of each sampling period. Stepwise multiple linear regressions analyses indicated that light fluctuations explained a part of this variability but a great part of variability stayed unexplained. F v/F m, ETRm and α were not only dependent on the light conditions of the sampling day but also on those of the previous days. A time lag of 3 days in the effect of light on ETRm and α variation was highlighted. At these time scales, changes in phytoplankton community structure seemed to have a low importance in the variability in photosynthetic parameters. The photoacclimation index E k showed a lower variability and was generally different from the incident irradiance, indicating a limited acclimation capacity with a poor optimization of light harvesting during the day. However, in well-mixed systems such as the Strait of Dover, the short-term photoacclimation is disrupted by the high level of variability in environmental conditions. Also, the variability observed in the present study can be associated with a particular kind of photosynthetic response: the “E k-independent” variability. The physiological basis of this photosynthetic response is largely unresolved and further researches on this subject are still required to better explain the dynamics of phytoplankton activity in the Strait of Dover.
@article{houliez_short-term_2013,
	title = {Short-term variability and control of phytoplankton photosynthetic activity in a macrotidal ecosystem (the Strait of Dover, eastern English Channel)},
	volume = {160},
	issn = {1432-1793},
	url = {https://doi.org/10.1007/s00227-013-2218-4},
	doi = {10.1007/s00227-013-2218-4},
	abstract = {Short-term changes in phytoplankton photosynthetic activity were studied during different periods of the years 2009 and 2010 in the coastal waters of a macrotidal ecosystem (the Strait of Dover, eastern English Channel). During each sampling period, samples were taken every 1.45 h., from sunrise to sunset, during at least 5 days distributed along a complete spring–neap tide cycle. The photosynthetic parameters were obtained by measuring rapid light curves using pulse amplitude modulated fluorometry and were related to environmental conditions and phytoplankton taxonomic composition. The maximum quantum yield (F v/F m) showed clear light-dependent changes and could vary from physiological maxima (0.68–0.60) to values close to 0.30 during the course of 1 day, suggesting the operation of photoprotective mechanisms. The maximum electron transport rate ({ETRm}) and maximal light utilization efficiency (α) were generally positively correlated and showed large diel variability. These parameters fluctuated significantly from hour to hour within each day and the intraday pattern of variation changed significantly among days of each sampling period. Stepwise multiple linear regressions analyses indicated that light fluctuations explained a part of this variability but a great part of variability stayed unexplained. F v/F m, {ETRm} and α were not only dependent on the light conditions of the sampling day but also on those of the previous days. A time lag of 3 days in the effect of light on {ETRm} and α variation was highlighted. At these time scales, changes in phytoplankton community structure seemed to have a low importance in the variability in photosynthetic parameters. The photoacclimation index E k showed a lower variability and was generally different from the incident irradiance, indicating a limited acclimation capacity with a poor optimization of light harvesting during the day. However, in well-mixed systems such as the Strait of Dover, the short-term photoacclimation is disrupted by the high level of variability in environmental conditions. Also, the variability observed in the present study can be associated with a particular kind of photosynthetic response: the “E k-independent” variability. The physiological basis of this photosynthetic response is largely unresolved and further researches on this subject are still required to better explain the dynamics of phytoplankton activity in the Strait of Dover.},
	pages = {1661--1679},
	number = {7},
	journaltitle = {Marine Biology},
	shortjournal = {Mar Biol},
	author = {Houliez, Emilie and Lizon, Fabrice and Lefebvre, Sébastien and Artigas, Luis Felipe and Schmitt, François G.},
	urldate = {2019-04-16},
	date = {2013-07-01},
	langid = {english},
	note = {Number: 7},
	keywords = {Phytoplankton, Photoprotective Mechanism, Photosynthetic Parameter, Phytoplankton Assemblage, Phytoplankton Community Structure}
}
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