title: Mercury in wintering seabirds, an aggravating factor to winter wrecks?
abstract: Every year, thousands of seabirds are cast ashore and are found dead along the coasts of North America and Western Europe. These massive mortality events called 'winter wrecks' have generally been attributed to harsh climatic conditions and prolonged storms which affect bird energy balance and impact their body condition. Nevertheless, additional stress factors, such as contaminant body burden, could potentially cumulate to energy constraints and actively contribute to winter wrecks. However, the role played by these additional factors in seabird massive winter mortality has received little attention to date. In February/March 2014, an unprecedented seabird wreck occurred along the Atlantic French coasts during which > 43,000 seabirds were found dead. By analyzing mercury (Hg) concentrations in various tissues collected on stranded birds, we tested the hypothesis that Hg played a significant role in this mortality. More specifically, we aimed to (1) describe Hg contamination in wintering seabirds found along the French coasts in 2014, and (2) determine if Hg concentrations measured in some vital organs such as kidney and brain reached toxicity thresholds that could have led to deleterious effects and to an enhanced mortality. We found some of the highest Hg levels ever reported in Atlantic puffins, common guillemots, razorbills and kittiwakes. Measured concentrations ranged from 0.8 to 3.6 μg · g(-1) of dry weight in brain, 1.3 to 7.2 μg · g(-1) in muscle, 2.5 to 13.5 μg · g(-1) in kidney, 2.9 to 18.6 μg · g(-1) in blood and from 3.1 to 19.5 μg · g(-1) in liver. Hg concentrations in liver and brain were generally below the estimated acute toxicity levels. However, kidney concentrations were not different than those measured in the liver, and above levels associated to renal sub-lethal effects, suggesting a potential Hg poisoning. We concluded that although Hg was not directly responsible for the high observed mortality, it has been a major aggravating stress factor for emaciated birds already on the edge. Importantly, this study also demonstrated that total blood, which can be non-lethally collected in seabirds, can be used as a predictor of Hg contamination in other tissues.
authors.affiliation: Littoral, Environnement et Sociétés, UMRi 7266 CNRS - Université La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France. Electronic address: fort.jerome@gmail.com.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Fort
authors.affiliation: Littoral, Environnement et Sociétés, UMRi 7266 CNRS - Université La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France. Electronic address: thomas.lacoue-labarthe@univ-lr.fr.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lacoue-Labarthe
authors.affiliation: Littoral, Environnement et Sociétés, UMRi 7266 CNRS - Université La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France; University of Science and Technology of Hanoi, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Viet Nam. Electronic address: linhnguyenhanh@gmail.com.
authors.forename: Hanh Linh
authors.initials: HL
authors.lastname: Nguyen
authors.affiliation: LPO (Ligue pour la Protection des Oiseaux), Fonderies Royales, 8 rue du Dr Pujos, 17305 Rochefort, France. Electronic address: amelie.boue@lpo.fr.
authors.forename: Amélie
authors.initials: A
authors.lastname: Boué
authors.affiliation: Observatoire PELAGIS, UMS 3462 CNRS - Université La Rochelle, La Rochelle, France. Electronic address: jerome.spitz@univ-lr.fr.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Spitz
authors.affiliation: Littoral, Environnement et Sociétés, UMRi 7266 CNRS - Université La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France. Electronic address: paco.bustamante@univ-lr.fr.
authors.forename: Paco
authors.initials: P
authors.lastname: Bustamante
mesh_terms: D025041:Animal Migration; D000818:Animals; D001717:Birds / Q000378:metabolism*; D046091:Charadriiformes; D004784:Environmental Monitoring; D005060:Europe; D008628:Mercury / Q000378:metabolism*; D009656:North America; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Bay of Biscay; Massive mortality; Mercury; North Atlantic; Seabirds; Winter wreck