%0 Journal Article %J Estuaries and Coasts %D 2018 %T Annual Phytoplankton Primary Production Estimation in a Temperate Estuary by Coupling PAM and Carbon Incorporation Methods %A Morelle, Jérôme %A Mathilde Schapira %A Francis Orvain %A Riou, Philippe %A Pascal Jean Lopez %A Duplessix, Olivier %A Rabiller, Emilie %A Maheux, Franc %A Simon, Benjamin %A Pascal Claquin %K High frequency . Electron requirement for carbon fixation . Electron transport rate (ETR) . Seine estuary %X

Phytoplankton primary production varies considerably with environmental parameters especially in dynamic ecosystems like estuaries. The aimof this study was to investigate short-term primary production along the salinity gradient of a temperate estuary over the course of 1 year. The combination of carbon incorporation and fluorescence methods enabled primary production estimation at short spatial and temporal scales. The electron requirement for carbon fixation was investigated in relation with physical-chemical parameters to accurately estimate primary production at high frequency. These results combined with the variability of the photic layer allowed the annual estimation of primary production along the estuary. Phytoplankton dynamics was closely related to salinity and turbidity gradients, which strongly influenced cells physiology and photoacclimatation. The number of electrons required to fix 1 mol of carbon (C) was ranged between 1.6 and 25 mol electron mol C−1 with a mean annual value of 8 ± 5 mol electron mol C−1. This optimum value suggests that in nutrient replete conditions like estuaries, alternative electron flows are low, while electrons transfer from photosystem II to carbon fixation is highly efficient. A statistical model was used to improve the estimation of primary production from electron transport rate as a function of significant environmental parameters. Based on this model, daily carbon production in the Seine estuary (France) was estimated by considering light and photic zone variability. A mean annual daily primary production of 0.12 ± 0.18 g C m−2 day−1 with a maximum of 1.18 g C m−2 day−1 in summer was estimated which lead to an annual mean of 64.75 g C m−2 year−1. This approach should be applied more frequently in dynamic ecosystems such as estuaries or coastal waters to accurately estimate primary production in those valuable ecosystems.

%B Estuaries and Coasts %8 02/2018 %G eng %0 Journal Article %J Harmful Algae %D 2017 %T Nutrient ratios influence variability in Pseudo-nitzschia species diversity and particulate domoic acid production in the Bay of Seine (France) %A Thorel, Maxine %A Pascal Claquin %A Mathilde Schapira %A Romain Le Gendre %A Riou, Philippe %A Didier Goux %A Bertrand Le Roy %A Raimbault, V %A Deton-Cabanillas, A.-F. %A Bazin, Pauline %A Kientz-Bouchart, Valérie %A Juliette Fauchot %K analogs and derivatives %K analysis %K Bay %K Bays %K Biodiversity %K chemistry %K Diatom %K Diatoms %K Domoic acid %K France %K Geography %K kainic acid %K Nitrates %K nitric acid derivative %K particulate matter %K phosphate %K Phosphates %K Physiology %K Phytoplankton %K Principal Component Analysis %K season %K Seasons %K species difference %K Species Specificity %K time factor %K Time Factors %X The population dynamics of different Pseudo-nitzschia species, along with particulate domoic acid (pDA) concentrations, were studied from May 2012 to December 2013 in the Bay of Seine (English Channel, Normandy). While Pseudo-nitzschia spp. blooms occurred during the two years of study, Pseudo-nitzschia species diversity and particulate domoic acid concentrations varied greatly. In 2012, three different species were identified during the spring bloom (P. australis, P. pungens and P. fraudulenta) with high pDA concentrations (∼1400 ng l−1) resulting in shellfish harvesting closures. In contrast, the 2013 spring was characterised by a P. delicatissima bloom without any toxic event. Above all, the results show that high pDA concentrations coincided with the presence of P. australis and with potential silicate limitation (Si:N < 1), while nitrate concentrations were still replete. The contrasting environmental conditions between 2012 and 2013 highlight different environmental controls that might favour the development of either P. delicatissima or P. australis. This study points to the key role of Pseudo-nitzschia diversity and cellular toxicity in the control of particulate domoic acid variations and highlights the fact that diversity and toxicity are influenced by nutrients, especially nutrient ratios. © 2017 Elsevier B.V. %B Harmful Algae %I Elsevier B.V. %V 68 %P 192-205 %G eng %U https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028543709&doi=10.1016%2fj.hal.2017.07.005&partnerID=40&md5=def23b37b0d16a1ae7ab65a7ef2b940b %R 10.1016/j.hal.2017.07.005 %0 Journal Article %J Harmful Algae %D 2017 %T Nutrient ratios influence variability in Pseudo-nitzschia species diversity and particulate domoic acid production in the Bay of Seine (France) %A Thorel, Maxine %A Pascal Claquin %A Mathilde Schapira %A Romain Le Gendre %A Riou, Philippe %A Goux, Didier %A Le Roy, Bertrand %A Raimbault, V %A Deton-Cabanillas, Anne-Flore %A Bazin, Pauline %A Kientz-Bouchart, Valérie %A Juliette Fauchot %K Bloom dynamics %K Domoic acid %K English Channel %K Nutrient ratios %K Pseudo-nitzschia Species diversity %X

The population dynamics of different Pseudo-nitzschia species, along with particulate domoic acid (pDA) concentrations, were studied from May 2012 to December 2013 in the Bay of Seine (English Channel, Normandy). While Pseudo-nitzschia spp. blooms occurred during the two years of study, Pseudo-nitzschia species diversity and particulate domoic acid concentrations varied greatly. In 2012, three different species were identified during the spring bloom (P. australis, P. pungens and P. fraudulenta) with high pDA concentrations (∼1400 ng l−1) resulting in shellfish harvesting closures. In contrast, the 2013 spring was characterised by a P. delicatissima bloom without any toxic event. Above all, the results show that high pDA concentrations coincided with the presence of P. australis and with potential silicate limitation (Si:N < 1), while nitrate concentrations were still replete. The contrasting environmental conditions between 2012 and 2013 highlight different environmental controls that might favour the development of either P. delicatissima or P. australis. This study points to the key role of Pseudo-nitzschia diversity and cellular toxicity in the control of particulate domoic acid variations and highlights the fact that diversity and toxicity are influenced by nutrients, especially nutrient ratios.

%B Harmful Algae %V 68 %P 192 - 205 %G eng %U http://www.sciencedirect.com/science/article/pii/S1568988317300148 %R https://doi.org/10.1016/j.hal.2017.07.005