Do Heavy Metal Concentrations Pose a Threat to Marine Turtles from the Mediterranean Sea?

Abstract

Concentrations of heavy metals (Hg, Cd and Pb) were determined in internal organs and nest contents of green turtles Chelonia mydas and loggerhead turtles Caretta caretta from northern Cyprus, eastern Mediterranean Sea. Concentrations of mercury in liver tissue were higher in loggerhead turtles (median 2.41 μg g −1 dry weight) than in green turtles (0.55 μg g −1 dry weight). Preliminary data suggest cadmium concentrations to be highest in kidney tissue of loggerhead turtles (median 30.50 μg g −1 dry weight) but in liver tissue of green turtles (median 5.89 μg g −1 dry weight). Concentrations of lead in internal tissues were often below analytical detection limits in both species, but when measurable, tended to be higher in loggerhead turtles. Concentrations of mercury and cadmium in nest contents from both species were low, often below analytical detection limits, while those of lead were relatively high in loggerhead turtle hatchlings (up to 10.56 μg g −1 dry weight). When measurable, concentrations of all three metals tended to be higher in loggerhead turtle nest contents than in green turtle nest contents. Results presented here are consistent with inter-specific differences in diet and trophic status. Heavy metal burdens in loggerhead turtles and green turtles from the Mediterranean are similar or lower than corresponding concentrations in turtles from Japan and Hawaii, but some lead concentrations in Mediterranean loggerhead hatchlings are at levels known to cause subclinical toxic effects in other vertebrates.