Dynamics of carbon assimilation by St Lawrence estuary phytoplankton at the end of summer |
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Authors: | Chantal Descolas-Gros Michel R. Fontugne |
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Affiliation: | (1) Laboratoire Arago, 66 650 Banyuls sur mer, France;(2) Centre des Faibles Radioactivités Laboratoire mixte CNRS-CEA, 91 190 Gif sur Yvette, France |
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Abstract: | This study presents data of in situ measurements of inorganic carbon assimilation by phytoplankton communities of the St Lawrence estuary during the end of summer 1982. We used carboxylase activity measurements (ribulose-1,5-bisphosphate carboxylase, carboxylases) and the 13C/12C ratio of phytoplankton organic carbon, expressed as 13C, to study patterns of assimilation. Upper estuary phytoplankton communities showed a smaller turn-over rate in carbon assimilation than lower estuary phytoplankton communities. Carbon assimilation was limited by light intensity in the upper estuary and by CO2 availability in the lower estuary. In the St Lawrence estuary, stable carbon isotope ratios of phytoplankton organic carbon seemed to be controlled by inorganic carbon availability rather than by phytoplankton metabolism. |
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Keywords: | estuary carbon carboxylases /content/k35283486685q354/xxlarge8706.gif" alt=" part" align=" MIDDLE" BORDER=" 0" >13C production phytoplankton |
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