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(W/EH102) Trophic chain in an estuary: A simplified model of PCB bioaccumulation. Le Gall, Anne Christine1, Loizeau, Véronique1, 1 ABSTRACT- A model of PCB bioaccumulation has been developed for the sea bass trophic chain in the Seine estuary. This model simulates the life cycles of three trophic levels: the lowest is represented by the zooplankton species Eurytemora sp., the top one by the sea bass Dicentrarchus labrax, and the intermediate one by four supra benthic organisms Neomysis integer, Palaemon longirostris, Crangon crangon, Pomatoschistus microps. This model allows to calculate the concentrations of 12 PCB congeners in each of these organisms. It is also possible to evaluate the contaminants concentrations in different sea bass age classes and to observe the variations in PCB contamination in the female sea bass as a result of spawning. These results have been validated with data obtained from field experiments in the Seine estuary (France). There is a requirement for such models of contaminants bioaccumulation to be applicable to more than one estuary. Such a generalisation can be done following several paths. Here, it has been chosen to replace the four compartments representing the four suprabenthic species by one or two model compartments. These compartments are defined by properties (such as growth, feeding, excretion, respiration) derived from those of the suprabenthic species initially represented. A sensitivity analysis shows how the model depends on these modifications and what errors are introduced in the final results. Key words: model, bioaccumulation, trophic chain, estuary |
