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

Total mercury (Hg) concentration and stable isotope ratios (delta C-13 and delta N-15) were used as chemical tracers in two crustaceans and four fish species that are targets of subsistence fishery in the inner estuary of the Paraiba do Sul River. This fluvial environment in southeast Brazil has a large historical utilization of Hg. delta N-15 was a better predictor of Hg concentration in the muscle (edible part) than delta C-13; 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.