1-D COUPLED PHYSICAL-BIOLOGICAL MODEL OF THE NORTHWESTERN MEDITERRANEAN SEA

A 1-D coupled physical-biological model of the ecosystem of the Liguri an Sea is described. The physical model has been adapted from a therma l dispersive lake model (Tassin, 1986), and the biological model from the sub-models AQUAPHY (Lancelot et al., 1991a) and H.S.B. (Billen and Servais, 1989). The biological model considers two types of phytoplan kton, diatoms and non-siliceous flagellates, to describe the response of the phytoplankton community and the related food-web to different t ypes of fertilization (by river, atmospheric deposition or deep water upwelling) with different N:Si ratios. This distinction, and the detai led description of the microbial loop, helps to distinguish between ne w and regenerated primary production. The model has been calibrated on FRONTAL 1986 data, obtained monthly at a long-term station (43 degree s 24'N,07 degrees 52'E). The quantitative biomass, its repartition bet ween diatoms and flagellates, and its spatio-temporal variability are reasonably well reproduced by the model. From these simulations, an an nual new production of 62 g C m(-2) is computed, contributing 35% of t otal annual primary production (180 g C m(-2)). This calculation refle cts the oligotrophic state of the system, where regenerated production occurs most of the year while the biomass remains low. A Monte-Carlo sensitivity analysis performed on the parameters driving the model lea ds to a confidence interval for the simulation and also to a better un derstanding of how the model functions. (C) 1997 Elsevier Science Ltd.