THE PRIMARY PRODUCTION MODULE IN THE MARINE ECOSYSTEM MODEL ERSEM-II,WITH EMPHASIS ON THE LIGHT FORCING

New elements in the primary production module of ERSEM II relative to ERSEM I are described. The main changes are the inclusion of picoalgae and dinoflagellates as additional functional groups, the decoupling o f carbon-and nutrient-uptake kinetics and the refining of the light de pendency of the primary producers, with emphasis on the last. The resu lts of a reference run are compared with measurements. The consequence s of using production-irradiance (p/l) relations assuming a different degree of photoinhibition in calculating net annual primary production are shown in a sensitivity analysis, and it is concluded that a p/I r elation with a high degree of photoinhibition leads to clear underesti mates of primary production in turbid coastal waters. (C) 1997 Elsevie r Science B.V. All rights reserved.