Stable isotope analyses revealed the influence of foraging habitat on mercury accumulation in tropical coastal marine fish
|Author(s)||Le Croizier Gael1, 2, Schaal Gauthier1, Point David2, Le Loc'h Francois1, Machu Eric3, 4, Fall Massal4, 5, Munaron Jean-Marie1, Boye Aurelien1, Walter Pierre2, Lae Raymond1, de Morais Luis Tito1|
|Affiliation(s)||1 : IUEM, Lab Sci Environm Marin LEMAR, UMR CNRS 6539, IFREMER,UBO,IRD, Rue Dumont dUrville,BP 70, F-29280 Plouzane, France.
2 : CNRS, UMR 5563, GET, IRD,UPS,CNES,OMP, 14 Ave Edouard Belin, F-31400 Toulouse, France.
3 : IUEM, UMR CNRS 6523, LOPS, UBO,IRD,IFREMER, Rue Dumont dUrville, F-29280 Plouzane, France.
4 : Univ Cheikh Anta DIOP Dakar, Lab Phys Atmosphere & Ocean Simeon Fongang, Ecole Super Polytech, BP 5085, Dakar, Senegal.
5 : ISRA, CRODT, BP 2241, Dakar, Senegal.
|Source||Science Of The Total Environment (0048-9697) (Elsevier Science Bv), 2019-02 , Vol. 650 , N. Part.2 , P. 2129-2140|
|WOS© Times Cited||23|
|Keyword(s)||Methylmercury sources, Trophic ecology, Feeding habitat, Metal bioaccumulation, Chemical tracers, Isotopic niche|
Bioaccumulation of toxic metal elements including mercury (Hg) can be highly variable in marine fish species. Metal concentration is influenced by various species-specific physiological and ecological traits, including individual diet composition and foraging habitat. The impact of trophic ecology and habitat preference on Hg accumulation was analyzed through total Hg concentration and stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) analyses in the muscle of 132 fish belonging to 23 different species from the Senegalese coast (West Africa), where the marine ecosystem is submitted to nutrients inputs from various sources such as upwelling or rivers. Species-specific ecological traits were first investigated and results showed that vertical (i.e. water column distribution) and horizontal habitat (i.e. distance from the coast) led to differential Hg accumulation among species. Coastal and demersal fish were more contaminated than offshore and pelagic species. Individual characteristics therefore revealed an increase of Hg concentration in muscle that paralleled trophic level for some locations. Considering all individuals, the main carbon source was significantly correlated with Hg concentration, again revealing a higher accumulation for fish foraging in nearshore and benthic habitats. The large intraspecific variability observed in stable isotope signatures highlights the need to conduct ecotoxicological studies at the individual level to ensure a thorough understanding of mechanisms driving metal accumulation in marine fish. For individuals from a same species and site, Hg variation was mainly explained by fish length, in accordance with the bioaccumulation of Hg over time. Finally, Hg concentrations in fish muscle are discussed regarding their human health impact. No individual exceeded the current maximum acceptable limit for seafood consumption set by both the European Union and the Food and Agriculture Organization of the United Nations. However, overconsumption of some coastal demersal species analyzed here could be of concern regarding human exposure to mercury.