The microbial food web in the European Regional Seas Ecosystem Model

In the framework of the complex dynamical European Regional Seas Ecosystem Model (ERSEM) a module describing the microbial part of the pelagic ecosystem has been developed. The module contains the carbon and nutrient dynamics of pelagic bacteria, heterotrophic flagellates and microzooplankton and interacts with the other parts of the model via phytoplankton, particulate and dissolved organic matter and mesozooplankton. A short description of the module is given and the results are discussed. It is demonstrated that in an application of ERSEM to the North Sea there is a gradual shift in dominance from the continental coast boxes to the offshore deeper areas between the different food webs, from what in the literature is termed the classical food web to the microbial food web, concomitant with a gradual decrease in the efficiency of the microbial loop.