Acquisition de données complémentaires aux dénombrements, avec les techniques de cytométrie en flux, fluorescence totale ou spectrale. Etat d’avancement et premiers résultats. Action Indice Composition. Livrable n° A III. Rapport final, 23 septemb...

The European Union Water Framework Directive (WFD) refers to phytoplankton as one of the biological quality elements that should be regularly monitored and evaluated thanks to three ecological indices: biomass, abundance and composition. The first two have already been defined, but the third one has not yet been proposed in the English Channel-Atlantic zone. The construction of a composition indice must consider the diversity of all the phytoplankton. As the microscopic counts concern only the micro-phytoplankton, it is necessary to use additional information which concerns the nano- and pico-phytoplankton, of great importance when estimating the phytoplankton diversity. These components of the phytoplankton can be measured by different complementary techniques: traditional or scanning flow cytometry, HPLC pigments analysis, spectral fluorescence, FlowCAM / PhytoImage, genetic biodiversity. In order to define the indicators for the WFD, while considering the phytoplankton dynamics in all the marine waters, it is necessary to use high resolution approaches, thanks to the development of new sensors and data analysis tools. The actions described in the present report concern the samples and continuous measurements ongoing since 2013, carried out in collaboration between the LOG laboratory (CNRS UMR 8187) from Wimereux and the laboratory IFREMER LER/Boulogne, including the participation of laboratories DYNECO/PELAGOS, DYNECO/VIGIES from IFREMER, and LISIC-ULCO from Calais. The aim was to continue the comparison of results obtained by different innovative techniques, as the flow cytometry and the spectral fluorescence, by applying these techniques to samples that come from networks or monitoring cruises ongoing in Eastern English Channel. These measurements were carried out referring to microscopic counts and pigments analysis (traditional methods used as reference for phytoplankton monitoring). These innovative techniques, when used at high resolution, permit a better understanding of the phytoplankton diversity and allow not only the construction of a composition indice for the WFD, but help bringing some important information, that could be used to estimate the ecological quality of all marine waters, in the frame of the Marine Strategy Framework Directive