DOLPHINS AS INDICATORS OF MICROPOLLUTANT TROPHIC FLOW IN AMAZON BASIN
Keywords:Brazil, Amazon, cetacean, mercury, organochlorines.
This study presents an overview of the appropriateness of the use of Amazonian cetaceans as sentinel species for environmental contamination by micropollutants, such as organochlorines and mercury. Due to the top position in food webs occupied by cetaceans and to their long life-span, high micropollutant concentrations have been verified in their tissues, what allows an amplification of the determination capacity by different analytical procedures. Besides providing an analytical advantage, the continuous micropollutant determination in cetaceans has been useful: as a reference of pollutant availability to other organisms; to integrate a complex signal of pollution; to quantify the ecological significance of a contamination. Therefore, published information on the concentrations of the quoted pollutants in the Amazonian cetaceans Inia geoffrensis (boto) and Sotalia fluviatilis (tucuxi) were gathered herewith. Carrying out comparison with data from Brazilian coastal cetaceans, it became clear how high the levels observed in Amazonian aquatic mammals are. In this context, mercury deserves to be highlighted. Despite the little volume of information on the concentrations of mercury, polychlorinated biphenyls and dichlorodiphenyltrichloroethane in Amazonian cetaceans, the existing information already demonstrates that the levels observed mirror the environmental contamination by such pollutants in distinct Amazonian environments. Perspectives for future investigations are also discussed, including possible ways of overcoming obstacles related to sampling of Amazonian cetaceans.