Age-Related Mercury Contamination and Relationship with Luteinizing Hormone in a Long-Lived Antarctic Bird

• Main Authors: Tartu, Sabrina, Bustamante, Paco, Goutte, Aurélie, Cherel, Yves, Weimerskirch, Henri, Bustnes, Jan Owe, Chastel, Olivier
• Other Authors: Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Norwegian Institute for Nature Research (NINA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: age; mercury; Pagodroma nivea; Luteinizing hormone; stable isotopes; sex-related segregation; Antarctica; [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology; Antarctic; Nivea; Antarc*; Snow Petrels
• Online Access: https://hal.archives-ouvertes.fr/hal-01079318; https://hal.archives-ouvertes.fr/hal-01079318/document; https://hal.archives-ouvertes.fr/hal-01079318/file/Tartu%20et%20al%202014%20PlosOne.pdf; https://doi.org/10.1371/journal.pone.0103642.t004

International audience Seabirds, as long-lived top predators, accumulate contaminants such as mercury (Hg), an established endocrine disruptor. In long lived species hormonal secretion varies with age; therefore, Hg-induced endocrine disruption may be exacerbated in some age classes. Here we investigated relationships between blood total Hg and luteinizing hormone (LH, a key pituitary hormone for the onset of breeding), in pre-laying known-age (11-45 years old) snow petrels (Pagodroma nivea) from Adélie Land, Antarctica. We predicted that 1) blood Hg would increase with advancing age as a consequence of bio-accumulation; and that 2) increasing blood Hg would be related to decreased concentrations of LH in the most Hg-contaminated individuals. Hg concentrations were higher in females than in males (p<0.001), and contrary to our prediction, decreased with advancing age in males (p=0.009) and tended to do so in females (p=0.06). The analysis of stable isotopes (δ13C and δ15N) suggested that this unexpected pattern could originate from age and sex-related variations in trophic niche, and hence Hg exposure. Regarding LH, our prediction was only supported in young birds (≤ 23 years) where baseline LH was inversely correlated with Hg concentrations (p=0.04). Hg burden did not predict baseline LH or GnRH-induced LH in birds that were more than 23 years old. These results show that age and contaminants may interfere with major endocrine mechanisms and, together with other recent studies, support the view that Hg could be connected to LH secretion and could then impair the fitness of long-lived birds.