MODELING THE IMPACT OF CULTIVATED FILTER- FEEDERS ON PHYTOPLANKTONIC BIOMASS OF THE THAU LAGOON (FRANCE)

A model coupling a 2D transport equation and a simple model of the nit rogen cycling was developed for the Thau lagoon (France). The model to ok into account the wind forcing on the hydrodynamism, the effect of t he temperature on the biological processes, the input of the watershed area the light dependence of the pelagic primary production and the p redation of the phytoplankton by the cultivated filter feeders. The mo del ran under two steady-state situations of wind with constant temper ature and light values corresponding to spring weather conditions. Sim ulations showed that the biological flows were very sensitive to the w ind. The budget of the nitrogen flows were computed for the three area s devoted to the filter feeder cultivation and the results highlighted the impact of cultivated oysters as a source of nutrients and an impo rtant nitrogen flow through the predation of phytoplankton.