Evidence that Pacific tuna mercury levels are driven by marine methylmercury production and anthropogenic inputs
Year: 2022
Type: article
Abstract: Pacific Ocean tuna is among the most-consumed seafood products but contains relatively high levels of the neurotoxin methylmercury. Limited observations suggest tuna mercury levels vary in space and time, yet the drivers are not well understood. Here, we map mercury concentrations in skipjack tuna across the Pacific Ocean and build generalized additive models to quantify the anthropogenic, ecological, and biogeochemical drivers. Skipjack mercury levels display a fivefold spatial gradient, with maximum concentrations in the northwest near Asia, intermediate values in the east, and the lowest levels in the west, southwest, and central Pacific. Large spatial differences can be explained by the depth of the seawater methylmercury peak near low-oxygen zones, leading to enhanced tuna mercury concentrations in regions where oxygen depletion is shallow. Despite this natural biogeochemical control, the mercury hotspot in tuna caught near Asia is explained by elevated atmospheric mercury concentrations and/or mercury river inputs to the coastal shelf. While we cannot ignore the legacy mercury contribution from other regions to the Pacific Ocean (e.g., North America and Europe), our results suggest that recent anthropogenic mercury release, which is currently largest in Asia, contributes directly to present-day human mercury exposure.
Authors: Anaïs Médieu, David Point, Takaaki Itai, Hélène Angot, Pearse J. Buchanan, Valérie Allain, Leanne Fuller, Shane Griffiths, David P. Gillikin, Jeroen E. Sonke, Lars-Eric Heimbürger-Boavida, Marie-Maëlle Desgranges, Christophe E. Menkes, Daniel J. Madigan, Pablo Brosset, Olivier Gauthier, Alessandro Tagliabue, Laurent Bopp, Anouk Verheyden, Anne Lorrain
Institutions: Centre National de la Recherche Scientifique, Ifremer, Université de Bretagne Occidentale, Laboratoire des Sciences de l'Environnement Marin, Institut de Recherche pour le Développement, Université de Bretagne Occidentale, Université Toulouse III - Paul Sabatier, Observatoire Midi-Pyrénées, Géosciences Environnement Toulouse, The University of Tokyo, École Polytechnique Fédérale de Lausanne, University of Liverpool, Pacific Community, Inter-American Tropical Tuna Commission, Union College, Université de Toulon, Aix-Marseille Université, Institut National des Sciences de l'Univers, Institut Méditerranéen d’Océanologie, University of New Caledonia, University of Reunion Island, Écologie Marine Tropicale des Océans Pacifique et Indien, University of Windsor, Institut Agro Rennes-Angers, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Dynamique et durabilité des écosystèmes : de la source à l'océan, École Polytechnique, Université Paris Sciences et Lettres, École Normale Supérieure - PSL, Sorbonne Université, Laboratoire de Météorologie Dynamique, Institut Pierre-Simon Laplace
Language: English
Subfield: Health, Toxicology and Mutagenesis
Field: Environmental Science
Domain: Physical Sciences
SDG: Life below water
Open Access status: hybrid
Awards: MRI: Acquisition of a Stable Isotope Ratio Mass Spectrometer for Interdisciplinary Research and Undergraduate Research Training, G195474297, G2659019386, G6803667113, Measurement-Based understanding of the aeRosol budget in the Arctic and its Climate Effects, Unraveling the origin of methylmercury toxin in marine ecosystems, Interdisciplinary Graduate School for the Blue planet, G993971353
OpenAlex ID: W4206332467