From Past Use to Present Effects: Total Mercury in Crustaceans and Fish in the Inner Estuary of Paraíba do Sul River, Southeast Brazil.

Total mercury (Hg) concentration and stable isotope ratios (δC and δN) were used as chemical tracers in two crustaceans and four fish species that are targets of subsistence fishery in the inner estuary of the Paraíba do Sul River. This fluvial environment in southeast Brazil has a large historical utilization of Hg. δN was a better predictor of Hg concentration in the muscle (edible part) than δC; i.e., the Hg concentration was more closely related to the trophic position of species than species' trophic habitat. Consumers at higher trophic levels had higher Hg concentrations. The Hg concentration was below the maximum permissible limits established by the Brazilian Government in fishery products, and there are no human risks related to its consumption.