Effects of chlordecone (Kepone) contamination on epilithic biofilm in rivers: identification of elements of bioindication – CHLORINDIC

Significant contamination by pesticides in some freshwater resources has been highlighted at the beginning of the 2000’s in Guadeloupe and Martinique Islands (French West Indies). Though they were banned from usage in the 1990’s, toxic and persistent molecules are still present in soils, with concentrations reaching 10 mg.kg-1 for the chlordecone (CLD) (Kepone®), the most worrying organochlorine (OC) residue, measured more than ten years after the last agricultural spreading. Driven by water cycle, this terrestrial pollution is progressively transferred into surrounding aquatic ecosystems, affecting both water and biota. Chlordecone levels measured in Guadeloupe and Martinique rivers are among the highest values detected worldwide in freshwater ecosystems. In this situation of recently discovered but large and geographically undetermined contamination, a quick regional ordinance prohibits fishing, personal consumption, and any kind of marketing of the aquatic organisms originating from most of the rivers. In a context where small-scale fisheries based on river crustaceans and fish contribute significantly to nutrition and sustainable livelihoods, so far, no organization or bioindicator was significantly found correlated with the contamination by chlordecone of the Caribbean freshwater ecosystems. This work fits into the scope of emerging needs in research about chlordecone impacts identified in the second Environmental Health Plan (2010-2013) and, moreover, proposes to acquire elements for new bioindicator of freshwater pollution in tropical islands. This project aims at developing innovative methods in the area of prevention and reduction of exposure, by undertaking research targeted on ecosystems of interest. The high specificity of aquatic ecosystems of these islands requires the development of new alternative methods for measuring, modelling, and characterizing the chemical contaminants and their metabolites. The first investigations recently performed on one possible effect of chlordecone on river stone epilithic biofilm revealed initial promising results. This avenue of investigation will be pursued under this program with the following objectives: i) to search for modifications in bacteria or microalgal communities, colonization processes, physical properties or chemical components (EPS) of biofilm linked with chlordecone pollution, ii) to search for bacterial strains indicative or resistant to chlordecone (or metabolizing chlordecone) in river biofilm, iii) to search for modifications in genetics or metabolism of epilithic diatom species correlated with pollutant and finally iv) to evaluate modifications in the consumption of biofilm by aquatic key-species of Caribbean rivers correlated with pollutant charge, and the expected impacts on Caribbean migrant species life cycles in rivers.