Approches de la capacité trophique des écosystèmes conchylicoles: synthèse bibliographique

Different methods for estimating the carrying capacity of areas cultivated by oyster or mussel farming are presented in order of complexity. The yield of production permits us to assess whether equilibrium is realized between the cultivated biomass and available food. Alternatively, study of the cultivated biomass and annual production could be used for building global dynamic models showing the maximum annual production that a bay can support. These approaches assume that the environment is constant. Study of the trophic relations for simulation of the growth rate of molluscs can be presented as a function of (i) the level of complexity of the coupling between the physical and biological model and (ii) the number of biological compartments. The physical aspects are often considered with a global approach and the ecosystem is represented by a large box where the residual fluxes and mean residence time are the physical variables. Some models are built with several boxes with residual fluxes between them; transport of the particular food is accounted for by a model of advection and dispersion. For the biological laws, the classical laws of bioenergetics of the cultivated population are used with filtration, ingestion, assimilation, and respiration which permit growth rate to be predicted. Generally, the biological compartments are not numerous when the physical models are complex, but in contrast certain biological models can have 10 to 30 biological boxes but with no physical approach, or at best a very rudimentary one. But the model, coupling a realistic physical model with the main biological compartments and their spatiotemporal variability, is not yet proposed.

This article is part of Marine Science Symposia Volume 192 - "The ecology and management aspects of extensive mariculture". To access other articles from this volume, please click on the keyword MSS Vol. 192.