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Environ Res. 2020 Feb;181:108908. doi: 10.1016/j.envres.2019.108908. Epub 2019 Nov 12.

Mercury and selenium concentrations, and selenium:mercury molar ratios in small cetaceans taken off St. Vincent, West Indies.

Author information

1
Department of Biology, Texas State University, Aquatic Station, San Marcos, TX, 78666, USA. Electronic address: mmccormack@txstate.edu.
2
Department of Earth and Environmental Systems, University of the South, Sewanee, TN, 37383, USA. Electronic address: russell.fielding@sewanee.edu.
3
Department of Biological Sciences, Center for Coastal Oceans Research, Institute of Water and the Environment, Florida International University, North Miami, FL, 33181, USA. Electronic address: jkiszka@fiu.edu.
4
Department of Biological Sciences, Center for Coastal Oceans Research, Institute of Water and the Environment, Florida International University, North Miami, FL, 33181, USA. Electronic address: vpaz003@fiu.edu.
5
Department of Earth Sciences, Dartmouth College, Hanover, NH, 03755, USA. Electronic address: brian.p.jackson@dartmouth.edu.
6
Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St. Kitts, West Indies. Electronic address: dbergfelt@rossvet.edu.kn.
7
Department of Biology, Texas State University, Aquatic Station, San Marcos, TX, 78666, USA. Electronic address: jdutton@txstate.edu.

Abstract

This study measured the concentration of total mercury (THg) and selenium (Se), and calculated the Se:Hg molar ratios in the muscle, blubber, liver, and kidney of small cetaceans (false killer whale, Pseudorca crassidens; killer whale, Orcinus orca; Risso's dolphin, Grampus griseus; short-finned pilot whale, Globicephala macrorhynchus; and dolphins of the genus Stenella) taken for human consumption off St. Vincent, West Indies. Overall, 122 samples were analyzed; mean THg concentrations (μg/g dry weight) were highest in the liver (730), followed by the kidney (274), muscle (76.4), and blubber (4.57). To explain variability in muscle THg concentrations, carbon (δ13C) and nitrogen (δ15N) stable isotope ratios were analyzed to explore differences in dietary carbon source and relative trophic position, respectively, among species. There was no relationship between δ15N and THg concentration, but there was a positive relationship between δ13C and THg concentration. On average for each species, the Se:Hg molar ratios were >1 in blubber and <1 in muscle. All liver samples and the majority of kidney, muscle, and blubber samples exceeded the FAO/WHO human consumption advisory level of 1 μg/g wet weight. Based on our estimations, consuming only 6.6 g of muscle a week would exceed the MeHg provisional tolerable weekly intake of 1.6 μg MeHg/kg body weight/week for a 60 kg person. Given the high THg concentration in these cetaceans and the frequency at which these tissues are consumed, this is a potential human health issue that warrants further investigation.

KEYWORDS:

Eastern caribbean; Mercury; Odontocete; Selenium:Mercury molar ratios; Stable isotopes

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