1. Organ-specific mercury stable isotopes, speciation and particle measurements reveal methylmercury detoxification processes in Atlantic Bluefin Tuna.
- Author
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Wiech M, Bienfait AM, Silva M, Barre J, Sele V, Bank MS, Bérail S, Tessier E, Amouroux D, and Azad AM
- Subjects
- Animals, Kidney metabolism, Spleen metabolism, Inactivation, Metabolic, Mercury metabolism, Mercury analysis, Environmental Monitoring methods, Muscles metabolism, Muscles chemistry, Selenium metabolism, Selenium analysis, Methylmercury Compounds metabolism, Methylmercury Compounds toxicity, Tuna metabolism, Mercury Isotopes metabolism, Water Pollutants, Chemical metabolism, Water Pollutants, Chemical toxicity, Water Pollutants, Chemical analysis
- Abstract
Identifying metabolism and detoxification mechanisms of Hg in biota has important implications for biomonitoring, ecotoxicology, and food safety. Compared to marine mammals and waterbirds, detoxification of MeHg in fish is understudied. Here, we investigated Hg detoxification in Atlantic bluefin tuna Thunnus thynnus using organ-specific Hg and Se speciation data, stable Hg isotope signatures, and Hg and Se particle measurements in multiple tissues. Our results provide evidence for in vivo demethylation and biomineralization of HgSe particles, particularly in spleen and kidney. We observed a maximum range of 1.83‰ for δ
202 Hg between spleen and lean muscle, whereas Δ199 Hg values were similar across all tissues. Mean percent methylmercury ranged from 8% in spleen to 90% in lean muscle. The particulate masses of Hg and Se were higher in spleen and kidney (Hg: 61% and 59%, Se: 12% and 6%, respectively) compared to muscle (Hg: 2%, Se: 0.05%). Our data supports the hypothesis of an organ-specific, two-step detoxification of methylmercury in wild marine fish, consisting of demethylation and biomineralization, like reported for waterbirds. While mass dependent fractionation signatures were highly organ specific, stable mass independent fractionation signatures across all tissues make them potential candidates for source apportionment studies of Hg using ABFT., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2024
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