Mercury in wintering seabirds, an aggravating factor to winter wrecks?

• Published in: Science of The Total Environment
• Main Authors: Fort, Jérôme, Lacoue-Labarthe, Thomas, Nguyen, Hanh Linh, Boué, Amélie, Spitz, Jérôme, Bustamante, Paco
• Other Authors: LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Marine Environment Laboratories Monaco (IAEA-MEL), International Atomic Energy Agency Vienna (IAEA), University of Science and Technology of Hanoi (USTH), LPO/ Birdlife France, Observatoire pour la Conservation de la Mégafaune Marine (PELAGIS), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), European Project: 631203,EC:FP7:PEOPLE,FP7-PEOPLE-2013-CIG,ARCTOX(2014)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Bay of Biscay; Massive mortality; Mercury; North Atlantic; Seabirds; Winter wreck; [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology; Arctic
• Online Access: https://hal.science/hal-01186129; https://hal.science/hal-01186129/document; https://hal.science/hal-01186129/file/Fort%20et%20al_revised_publication%20ready.pdf; https://doi.org/10.1016/j.scitotenv.2015.05.018

International audience Every year, thousands of seabirds 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 or 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 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. ...