Growth-related changes in heavy metal accumulation in green turtle (Chelonia mydas) from Yaeyama Islands, Okinawa, Japan.

Concentrations of nine heavy metals (Fe, Mn, Zn, Cu, Pb, Ni, Cd, Co, and Hg) were determined in liver, kidney, and muscle of 50 green turtles (Chelonia mydas) collected from Yaeyama Islands, Okinawa, Japan, to elucidate growth-related changes in heavy metal accumulation during different growth stage. Considerably high Cu concentrations were found in the liver of smaller turtles. Mean hepatic concentration of Cu was 50.2 microg/g wet weight which varied widely (4.27-113 microg/g wet weight). Cadmium concentrations decreased with increasing the carapace length. The juvenile green turtles in the pelagic ocean are likely feed on zooplankton, while adult coastal inhabiting green turtles mainly feed on sea grasses and seaweeds. Concentrations of Cd in sea plants are lower than those in zooplankton. The specific accumulation of Cd found in the green turtle seems to be attributable to their feeding habit, which is a shift from carnivore to herbivore at different growth stages.