Impact de la pollution aux hydrocarbures sur l'écophysiologie et la pathologie des bivalves d'intérêt commercial de la Côte Atlantique

The evaluation of the ecological and economical consequences of the hydrocarbon pollution of the Erika implies the setting up of monitorings, analysis and experiments in the short, medium and long term. Among the consequences to be evaluated, a great deal of attention has to be paid to the direct impact on the biology and production performances of the main shellfish species as about 30% of the national production (around 130,000 tons of oysters and 60,000 tons of mussels per year) is cultivated in the impacted area. The main difficulty in evaluating the effects of the contaminants on a distinct part of the ecosystem which is mostly dominated by a cultured population dwells in the different approaches to set up as well as the variability of the answers according to the studied species. As a matter of fact, the short term effects of an acute toxicity possibly affecting part of the stocks which are exposed to massive pollution inputs have to be distinguished from the delayed effects of a chronic toxicity caused by a low exposure and a sub-lethal bio-accumulation. Oyster and mussel species are considered as being really good bio-accumulators of trace elements and micro pollutants, with a limited regulation capacity to limit the accumulation of contaminants in their tissues (De Kock and Kramer, 1994). This justifies their use by some national bio-monitoring networks ("Mussel watch" in the US, RNO in France).