Teneur en mercure dans les moules du littoral français

Our results show that the contamination of the French coasts by mercury is quite low, and that if there is a greater contamination, it is extremely localized. In this way, in the roadsted of Toulon, where numerous samplings have been conducted, cultivated mussels are barely contaminated whereas those which grow a few kilometres away, on the docks of the arsenal show high concentrations, due to waste from the workshops. A sample collected on an old ship hull showed a content close to 5 mg/kg; the reason for this high content is most probably the presence of mercury salts used as an antifouling agent in the painting of the hull. Therefore, it seems that the risk of mercury contamination is very low apart from the fauna living in the polluted parts of the coast, where shellfish collection is forbidden anyway. But this fauna can be the prey of species living off the coast, which explains the mercury content found in pelagic species like tunas who feed on sardines living closer to the coast. As a reminder, one needs to note that the values found in these species, near the French coast, are generally way below the values which would be hazardous for consumers. However, some of them are the sign of an unwanted input for the future of the marine environment.