Foraging ecology drives mercury contamination in chick gulls from the English Channel

• Published in: Chemosphere
• Main Authors: Binkowski, Lukasz, Fort, Jérôme, Brault-Favrou, Maud, Gallien, Fabrice, Leguillou, Gilles, Chastel, Olivier, Bustamante, Paco
• Other Authors: Pedagogical University of Krakow, LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Groupe Ornithologique Normand (GONm), Maison de l'estuaire de la Seine, Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), GIP Seine Aval, Ecotones (GIP Seine Aval)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: chicks; mercury; bioaccumulation; stable isotopes; feeding ecology; seabird; [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology; Lesser black-backed gull
• Online Access: https://hal.science/hal-02987558; https://hal.science/hal-02987558/document; https://hal.science/hal-02987558/file/Binkowski%20et%20al%202021%20CHEM.pdf; https://doi.org/10.1016/j.chemosphere.2020.128622

International audience Although mercury (Hg) occurs naturally, human activity is currently the greatest source of release and the ocean receives Hg inputs by rivers and atmospheric deposition. Seabirds including chicks serve as valuable bioindicators of Hg contamination, reflecting local contamination around the colony. This study investigates the ecological drivers (trophic position and foraging habitat) influencing Hg concentrations in blood and feathers of chicks of three sympatric marine gull species. Chicks were sampled between 2015 and 2017 in the Seine estuary, one of the most Hg contaminated rivers in Europe, and in the Normand-Breton Gulf (the Chausey Islands), 200 km west, as a reference site with limited contaminant inputs. The trophic status of the chicks was evaluated based on the relative abundance of stable isotopes (δ13C, δ15N and δ34S). There was a tight correlation between Hg concentrations, as well as the abundance of stable isotopes, in blood and feathers. Great black-backed gull had the highest blood Hg concentrations of the species (1.80±0.92 µg⋅g-1 dry weight (dw)); the Lesser black-backed gull had intermediate concentrations (0.61±0.18 µg⋅g-1 dw); and the European herring gull had the lowest (0.37±0.26 µg⋅g-1 dw). Individuals with the highest trophic position showed consistently the highest Hg concentrations. The positive relationship between Hg concentrations and the feeding habitat (marine vs terrestrial) indicated that the main source of Hg for gulls in the English Channel is marine prey. This exposure led to relatively high Hg concentrations in Great black-backed gull, which may produce toxic effects to individuals with potential consequences for their populations.