Mercury in freshwater, estuarine, and marine fishes from Southern Brazil and its ecological implication

In this study, we measured the mercury concentration in 27 different fish species with high commercial value. Samples were taken from a region characterized by the diversity of aquatic environments. Mercury concentration in marine fish species varied from 30.4 to 216 ng g (-aEuro parts per thousand 1), while in estuarine species, it varied from 12.4 to 60.3 ng g (-aEuro parts per thousand 1). Compared to mercury concentration in marine species, none of the specimens from estuarine environment has reached a mercury concentration of 100 ng g (-aEuro parts per thousand 1). However, mercury concentrations in species from the freshwater Patos lagoon are remarkably higher (15.3 to 462 ng g (-aEuro parts per thousand 1)) than those from the estuarine or marine region. Even though mercury concentrations in these fish species did not exceed the maximum level (500 ng g (-aEuro parts per thousand 1)) allowed by WHO for human consumption, they represent the main food source for sea birds and mammals coming from South Pole during their migration period.