Ecological modelling, an objective tool for an integrated study of ecosystems

Abstract

The concepts of ecological modelling and its use for marine ecosystem dynamic studies are presented. The necessary steps for modelling primary biomass variations are described as theorical examples: (a) to gather quali-quantitative data on structure of the system (state variables) and on factors (forcing function), (b) a conceptual diagram of the phytoplankton system is established including compartments (nutrients, phytoplankton, herbivorous zooplankton) and energy fluxes (arrows between compartments: photosynthetic rate, respiration, grazing...) measured in situ or in vitro, (c) mathematical equations of the model are built up for each variable as a function of time: then, these equations are programmed and processed on computer with real data, (d) the result of simulation is compared to a serie of real data and the model is modified in case of excessive divergency. Ecological modelling is not only a tool for prevision, but is mainly an objective method for guiding researchs, formulating hypothesis, revealing deficiencies and orienting the sampling. Finally, on acount of its multidisciplinarity, ecological modelling is a tool of communication and the best vehicle of information between researchers of different areas.