Micropollutant content of Sargassum drifted ashore: arsenic and chlordecone threat assessment and management recommendations for the Caribbean

Abstract Massive Sargassum beachings occur since 2011 on Caribbean shores. Sargassum inundation events currently involve two species, namely S. fluitans and S. natans that are circulating and blooming along the North Atlantic subtropical gyre and in the entire Caribbean region up to the Gulf of Mexico. Alike other brown seaweeds, Sargassum have been shown to bioaccumulate a large number of heavy metals, alongside with some organic compounds including the contamination by historical chlordecone pollution in French West Indies (FWI), an insecticide used against the banana’s weevil Cosmopolites sordidus. The present study reports, during two successive years, the concentration levels of heavy metals including arsenic in Martinique and Guadeloupe (FWI). We found that Sargassum can also accumulate high concentration of chlordecone. Sargassum contamination by chlordecone is observed in areas that are close to contaminated river mouth. Our results further demonstrate that algae bleaching raises a number of questions about inorganic and organic pollutants bioaccumulation, transport and dissemination.