Trace element accumulation in green turtles (Chelonia mydas) foraging in locations of differing chemical input

Green sea turtles ( Chelonia mydas ) have high ecological, economic and cultural importance, and their high fidelity to foraging grounds and long lifespan make them good bioindicators of trace element pollution. Trace elements accumulate in green turtles through food, and are linked with disease and abnormalities. Previous studies suggest higher concentrations of trace elements within inshore locations, closer to anthropogenic activities and coastal run-off, compared to remote offshore sites. This project investigated trace element accumulation in blood of green turtles foraging in locations of differing chemical input. Blood was collected from green turtles foraging at three sites: Port Curtis (adjacent to industrial port), Heron Reef (adjacent to tourist resort and research station), and Hoskyn/Fairfax reefs (remote offshore reefs). The blood was acid digested and analysed using ICP-MS for trace element concentrations. Concentrations of individual elements were statistically analysed for differences between locations, and a principal components analysis was used to assess multivariate differences between locations. Trace element concentrations were also compared to reference intervals (RIs) from the literature. Antimony, cobalt, manganese, and molybdenum concentrations were significantly higher in Port Curtis turtles, and elevated above the reference intervals. Arsenic, selenium and cadmium were significantly higher in both offshore locations compared to Port Curtis, and elevated above reference intervals. Vanadium was significantly higher in Hoskyn/Fairfax turtles, and elevated above reference intervals. Principal component analyses found a distinct separation between Port Curtis and the Capricorn Bunker, as well as some separation between Heron and Hoskyn/Fairfax reefs. The higher concentrations of elements in turtle blood compared to the reference intervals, and other global populations, demonstrates natural and anthropogenic sources of elements are accumulating in these green turtles at elevated levels, with suspected risk to their health and the health of the marine environment.