Rapid temporal decline of mercury in Greenland halibut (Reinhardtius hippoglossoides)

Michael S Bank (1) , Sylvia Frantzen (2) , Arne Duinker (1) , David Amouroux (3) , Emmanuel Tessier (3) , Kjell Nedreaas (2) , Amund Maage (2) , Bente M Nilsen (2)

1 IMR - Austevoll Research Station
2 IMR - Institute of Marine Research [Bergen]
3 IPREM - Institut des sciences analytiques et de physico-chimie pour l'environnement et les materiaux

Mercury (Hg) pollution in the ocean is an issue of global concern, however bioaccumulation regimes of this ubiquitous pollutant in marine apex predators have important knowledge gaps. Our fish length and stable isotope (δ 15 N and δ 13 C) normalized data of Greenland halibut (GH) (Reinhardtius hippoglossoides) showed that Hg bioaccumulation in fillet tissue decreased by ~35-50 %, over a ten-year period from 2006 to 2015 (n = 7 individual sampling years). Hg was predominantly in the methylmercury form (>77 %). Results from a Bayesian information theoretic model showed that GH Hg concentrations decreased with time and its associated declines in Hg air emissions, estimated trophic position, and a potentially lower degree of demersal prey use as indicated by temporal trend shifts in nitrogen (δ 15 N) and carbon (δ 13 C) stable isotope values. GH trophic shifts accounted for about one third of the observed temporal reduction in Hg. Our study demonstrates the importance of simultaneously considering Hg emissions, food web dynamics and trophic shifts as important drivers of Hg bioaccumulation in a marine, deep water fish species and highlights the effectiveness of Hg regulations on ocean apex predator Hg concentrations and overall seafood safety.

Keywords: Mercury; Seafood; Ocean; Greenland halibut; Stable isotopes; Bioaccumulation

Domains: Material chemistry; Polymers; Theoretical and/or physical chemistry; Analytical chemistry

Michael S Bank, Sylvia Frantzen, Arne Duinker, David Amouroux, Emmanuel Tessier, et al.. Rapid temporal decline of mercury in Greenland halibut (Reinhardtius hippoglossoides). Environmental Pollution, 2021, 289, pp.117843. ⟨10.1016/j.envpol.2021.117843⟩. ⟨hal-03450483⟩