Hg and δ15N in juvenile green turtles from southeastern Brazil (~23°S): Inferences about contamination levels and recruitment to coastal waters

Abstract

Total mercury (THg) and δ15N were analysed in liver and muscle of juvenile green turtles (Chelonia mydas) from a foraging site in southeastern Brazil (~23°S) to evaluate contamination levels and make inferences about the timescale that animals were recruited from oceanic to coastal waters. The values for THg and δ15N in liver and muscle were 432.2 and 72.8 μg kg−1 and 10.0‰ and 9.2‰, respectively. THg concentrations in tissues indirectly indicated that the main food resources for this consumer (i.e., macroalgae) had negligible levels of this element. Thus, this foraging site could be considered a pristine area in terms of Hg contamination. The THg and δ15N in liver were derived by more recent food ingestion than those in muscle. The juvenile green turtles that died because of incidental captures in fisheries practiced along this foraging site were individuals newly recruited from oceanic waters.