Interdisciplinary methods for successful ecological simulation

Ecosystem modelling demands knowledge of chemical and biological interactions operating within their physical environment and the model must be formulated using mathematical algorithms written within the context of specific computer hardware and software. It is neither desirable nor necessary for each participant within a modelling project to be familiar with all of these disciplines but techniques must be available to ensure the compatibility of algorithms and the integrity of the whole. The European Regional Seas Ecosystem Model has been formulated by a multidisciplinary multinational team using techniques designed to facilitate modelling and circumvent these inherent problems. The methodology involves a modular approach to modelling, engineered within a user-friendly computer environment. Each partner is responsible for the successful implementation of at least one module, although expertise is drawn from the most appropriate sources available to all partners. A comprehensive set of state variables was selected by consultation between all of the partners and computer-coded names assigned to each of these. Other standard names are assigned to common processes such as feeding, respiration, growth and defaecation so facilitating mutual understanding of the import of each others modules. Progress is controlled by the definition of a ‘standard model’ which contains only those modifications which have been independently tested and approved by the quality control partner. The model, which is designed as a generic shelf sea simulator, is verified against data from one geographical area of the North Sea. Comparison of model output against measurements from the remaining nine geographical areas is taken as the means of model validation. The model is to be used to predict long-term effects of anthropogenic inputs of nutrients on the whole North Sea system and short-term changes along the coastal strip.