Review of gross community production, primary production, net community production and dark community respiration in the Gulf of Lions

Abstract

Thirty years of data were used to examine the influence of the Rhoˆne River discharge on the spatio-temporal distribution of primary production in the Gulf of Lions. These patterns are characterised for four hydrological provinces: (i) the Gulf of Marseilles, a coastal oligotrophic system exhibiting a typical diatom-based bloom succession; (ii) the mouth and plume of the Rhoˆne River, containing high levels of nutrients, constant levels of chlorophyll a, and a plankton assemblage dominated by nanoflagellates; (iii) the highly productive dilution area to the west of the Rhoˆne, with a diatom spring bloom and smaller winter diatom blooms; (iv) the southern area encompassing the oligotrophic Liguro-Provençal Current, a frontal zone of constantly high primary production and a divergence area exhibiting a typical spring bloom situation.No evidence of eutrophication due to river input was seen. In situ and in vitro net community production data suggest the Gulf of Lions as a whole is a balanced ecosystem on an annual time scale, with the mean primary production lying between 78 and 142 g C m−2 a−1.