Mercury levels in muscle of six species of turtles eaten by people along the Rio Negro of the Amazon basin.

Mercury levels in the Amazon River are generally high, but there are no published studies on Hg levels in turtles from the region. In this study, levels of Hg were examined in the muscle of six species of turtles in the Rio Negro in the Amazon basin of Brazil, including Podocnemis unifilis, Podocnemis expansa, Podocnemis erythrocephala, Podocnemis sextuberculata, Peltocephalus dumerilianus, and Chelus fimbriatus. It is important to analyze Hg levels in chelonians in this region because of the potential health risk to humans and other receptors that eat them, as well as their potential use as bioindicators.

Mercury bioacumulation in four tissues of Podocnemis erythrocephala (Podocnemididae: Testudines) as a function of water parameters.

A number of environmental factors influence the dynamics of Hg in aquatic ecosystems, yet few studies have examined these factors for turtles, especially from South America. Red-headed river turtle (Podocnemis erythrocephala) is easy to capture in the black waters of Rio Negro, making it the turtle species that is consumed most often by people of the region. In this study, environmental factors and turtle size were investigated to determine their influence on the Hg concentration in blood, muscle, liver and carapace of the red-headed river turtle.

Factors controlling Hg levels in two predatory fish species in the Negro river basin, Brazilian Amazon.

A number of environmental factors have been shown to influence the dynamics of Hg in aquatic ecosystems. Here we investigate the influence of fish size, pH, dissolved organic carbon (DOC), and the availability of potential methylation sites (floodplain forests and hydromorphic soils) on the concentration of total Hg in two carnivorous fishes: Cichla spp. and Hoplias malabaricus in the Negro River, Brazil.