Mercury bioaccumulation patterns and toxicological risk across tissues in the Black-browed albatross (Thalassarche melanophris) from the Southwestern Atlantic.

Mercury (Hg) naturally occurs in the Earth's crust, is a toxic element and the most significant sources of contribution to the environment are metallic mining and the massive burning of biomass. Hg can be transported over long distances through both aquatic and atmospheric pathways. Once biotransformed in methylmercury (MeHg), it becomes highly toxic, accumulating and biomagnifying in food chains. In this study, we provide novel data on total Hg (THg) concentrations in six tissues of the Black-browed albatross (Thalassarche melanophris), a pelagic seabird from the Southwestern Atlantic, and analyze the influence of sex, age class and trophic position. The distribution of THg among sampled tissues followed the pattern: liver > gonad > kidney > brain = muscle > mesenteric fat with concentrations (mean ± SD) of 4.55 ± 4.42; 1.68 ± 0.93; 1.07 ± 0.31; 0.91 ± 0.42; 0.87 ± 0.41; and 0.16 ± 0.02 µg/g dry weight, respectively. Mercury levels were positively correlated among liver, muscle, and brain. Notably, liver of female showed THg concentrations that exceeded the thresholds associated with acute hepatic toxicity and reproductive impairments in several bird species. Despite sexual size dimorphism, Hg concentrations did not differ significantly between sexes. Overlapping feeding areas indicate that diet, rather than body size, drives Hg accumulation. Overall, our results provide valuable information on Hg levels in seabirds, contributing to assessments of the effectiveness evaluation of the Minamata Convention in the marine environment.