Biological and ecological traits rather than geography control mercury (Hg) in scutes of marine turtles from the Southwest Atlantic

The use of sentinel species in monitoring programs for toxic metals such as mercury (Hg) is essential to understand these pollutants' impact on the environment. For this purpose, it is essential to use organisms that have a lifespan compatible with the residence time of Hg in the oceans, and preferably with a wide geographical distribution, such as sea turtles. Here, we assess the regional variability of Hg concentrations using carapace scutes of four sea turtle species along the foraging and spawning area in the northeast coastline of Brazil. Mercury concentrations in samples showed no relationship with the environmental Hg levels (obtained from literature). Rather, Hg concentrations varied according to species-specific biological, and ecological traits. Characteristics such as the ontogenetic shift in the diet of Chelonia mydas, capital breeding in females, depth of foraging in oceanic waters, and selectivity of food items, such as in Eretmochelys imbricata, significantly influenced Hg concentrations. •Hg concentrations varied according to species-specific biological, and ecological traits.•Hg concentrations in the four species of sea turtles were not related to regional differences in Hg concentrations.•Carapace has proven to be a viable tool as an indicator of Hg concentration.•Hg concentrations in L. olivacea are most probably a reflection of its more oceanic distribution.