A STRUCTURE AND METHODOLOGY FOR MARINE ECOSYSTEM MODELING

Comprehensive ecosystem models involve aspects from each of the biolog ical, chemical and physical sciences. Consequently such models, for ex ample the European Regional Seas Ecosystem Model (ERSEM), are often ba sed on computer code written by a number of different research groups each with a well-defined area of responsibility. To construct a meanin gful integrated model capable of combining the expertise from each of these disciplines requires a formalized ecosystem structure that provi des a template for model development. Assumptions made at this stage w ill to a large extent determine the qualities of the resulting model. Essential too is a system of quality management that assures a correct and consistent end product. Such a system, however, requires the flex ibility to allow the various contributors the freedom to pursue indivi dual and novel representations of ecosystem function, if the model is to be ground breaking. The system adopted by the ERSEM group, which sh ould have a wider applicability than marine ecosystem modelling, is de scribed here. Finally, the methodology used to gauge the relative meri ts of alternative ecosystem representations is described.