Abstract

Chlordecone is a persistent organochlorine pesticide used in the banana fields of the French West Indies, from 1972 to 1993. Three marine habitats (mangroves, seagrass beds and coral reefs) of two study sites located downstream contaminat-ed rivers were chosen to evaluate the level of contamination of marine food webs. Each food chain studied included suspended organic matter, primary producers (macroalgae, algal turf, seagrass), zooplankton, symbiotic organisms (corals, sea anemones), primary consumers (herbivores, suspension feeders, biofilm feeders), omnivores and detritivores (lobsters, fish), secondary consumers (carnivores 1: invertebrate feeders, planktivores) and tertiary consumers (carnivores 2: inverte-brate and fish feeders) and piscivores. Log-linear regressions of the concentrations of chlordecone versus nitrogen isotopic ratios (δ15N) were used to assess the bioaccumulation of chlordecone along trophic food webs. On each site, both phenomena (bioconcentration and biomag-nification) were active on the transfer of chlordecone in marine organisms. In mangroves (i.e. close to the source of pollution), lower trophic magnification factors (TMF) indicated that bioconcentration prevailed on bioamplification phenomenon. In seagrass beds and coral reefs, the opposite phenomenon appeared: bioconcentration processes were less important and bioamplification pathway became dominant. Far from the source of pollution, molecules of chlordecone seemed to be transferred to organisms mostly via trophic interactions rather than water contact.

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