ABSTRACT
Most marine mammals are top predators that accumulate pollutants in their tissues through bioaccumulation and biomagnification processes. The effects of pollutants on marine mammals include immunosuppression, cancer, skin lesions, secondary infections, diseases, and reduced reproductive success. By determining the health status of marine mammals, it is possible to identify anthropogenic influences on the marine environmental health itself, and on the well-being of these animals. In this chapter, a brief description of marine mammals and a discussion on their role as sentinel species shall be made. Subsequently, emphasis shall be given to mercury contamination in these animals, since environmental exposure to Hg, particularly for higher trophic level consumers, is significantly higher than other elements, as this metal presents high toxicity and the ability to undergo biomagnification along trophic chains.
