1-D coupled physical-biological model of the northwestern Mediterranean Sea

A 1-D coupled physical-biological model of the ecosystem of the Ligurian Sea is described. The physical model has been adapted from a thermal dispersive lake model (Tassin, 1986), and the biological model from the sub-models AQUAPHY (Lancelot et al., 199l a) and H.S.B. (Billen and Servais, 1989). The biological model considers two types of phytoplankton, diatoms and non-siliceous flagellates, to describe the response of the phytoplankton community and the related food-web to different types of fertilization (by river, atmospheric deposition or deep water upwelling) with different N:Si ratios. This distinction, and the detailed description of the microbial loop, helps to distinguish between new and regenerated primary production. del has been calibrated on FRONTAL 1986 data, obtained monthly at a long-term station (43°24′N, 07°52′E). The quantitative biomass, its repartition between diatoms and flagellates, and its spatio-temporal variability are reasonably well reproduced by the model. From these simulations, an annual new production of 62 g C m−2 is computed, contributing 35% of total annual primary production (180 g C m−2). This calculation reflects the oligotrophic state of the system, where regenerated production occurs most of the year while the biomass remains low. e-Carlo sensitivity analysis performed on the parameters driving the model leads to a confidence interval for the simulation and also to a better understanding of how the model functions.