A structure and methodology for marine ecosystem modelling

Comprehensive ecosystem models involve aspects from each of the biological, chemical and physical sciences. Consequently such models, for example the European Regional Seas Ecosystem Model (ERSEM), are often based on computer code written by a number of different research groups each with a well-defined area of responsibility. To construct a meaningful integrated model capable of combining the expertise from each of these disciplines requires a formalized ecosystem structure that provides a template for model development. Assumptions made at this stage will 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 flexibility to allow the various contributors the freedom to pursue individual and novel representations of ecosystem function, if the model is to be ground breaking. The system adopted by the ERSEM group, which should have a wider applicability than marine ecosystem modelling, is described here. Finally, the methodology used to gauge the relative merits of alternative ecosystem representations is described.