Green Turtle (Chelonia mydas) Blood and Scute Trace Element Concentrations in the Northern Great Barrier Reef.

This article focuses on assessing metal contamination in green turtles (Chelonia mydas) from coastal and offshore sites of the Great Barrier Reef by analyzing metal concentrations in blood and scute samples. Blood metal levels, indicative of recent exposure, were generally similar across sites and mostly within published reference intervals, except for cobalt (Co), which was elevated—particularly at Upstart Bay—exceeding baseline values by up to 13-fold. Scute samples, representing longer-term accumulation, showed higher concentrations of several metals (e.g., aluminum, magnesium, zinc) than blood, suggesting past exposure to elevated metal levels. Multivariate analyses revealed distinct metal profiles among sites, with Upstart Bay's turtles notably influenced by Co, likely linked to natural mineral deposits and mining activities in the region. The study highlights the potential ecotoxicological risk of elevated Co to C. mydas health and recommends further research on long-term metal exposure using scute sampling and the development of region-specific reference intervals to improve monitoring and conservation efforts.