title: To breed or not to breed: endocrine response to mercury contamination by an Arctic seabird.
abstract: Mercury, a ubiquitous toxic element, is known to alter expression of sex steroids and to impair reproduction across vertebrates but the mechanisms underlying these effects are not clearly identified. We examined whether contamination by mercury predicts the probability to skip reproduction in black-legged kittiwakes (Rissa tridactyla) from Svalbard. We also manipulated the endocrine system to investigate the mechanism underlying this relationship. During the pre-laying period, we injected exogenous GnRH (gonadotropin-releasing hormone) to test the ability of the pituitary to release luteinizing hormone (LH, a key hormone for the release of sex steroids and hence breeding) in relation to mercury burden. Birds that skipped reproduction had significantly higher mercury concentration in blood than breeders. Endocrine profiles of these birds also varied based on breeding status (breeders versus non-breeders), mercury contamination and sex. Specifically, in skippers (birds that did not breed), baseline LH decreased with increasing mercury concentration in males, whereas it increased in females. GnRH-induced LH levels increased with increasing mercury concentration in both sexes. These results suggest that mercury contamination may disrupt GnRH input to the pituitary. Thus, high mercury concentration could affect the ability of long-lived birds to modulate their reproductive effort (skipping or breeding) according to ongoing environmental changes in the Arctic, thereby impacting population dynamics.
authors.affiliation: Centre d'Etudes Biologiques de Chizé (CEBC), UPR 1934-CNRS, 79360 Beauvoir-sur-niort, France. tartu@cebc.cnrs.fr
authors.forename: Sabrina
authors.initials: S
authors.lastname: Tartu
authors.forename: Aurélie
authors.initials: A
authors.lastname: Goutte
authors.forename: Paco
authors.initials: P
authors.lastname: Bustamante
authors.forename: Frédéric
authors.initials: F
authors.lastname: Angelier
authors.forename: Børge
authors.initials: B
authors.lastname: Moe
authors.forename: Céline
authors.initials: C
authors.lastname: Clément-Chastel
authors.forename: Claus
authors.initials: C
authors.lastname: Bech
authors.forename: Geir Wing
authors.initials: GW
authors.lastname: Gabrielsen
authors.forename: Jan Ove
authors.initials: JO
authors.lastname: Bustnes
authors.forename: Olivier
authors.initials: O
authors.lastname: Chastel
mesh_terms: D000818:Animals; D001110:Arctic Regions; D046091:Charadriiformes / Q000502:physiology*; D004785:Environmental Pollutants / Q000097:blood / Q000633:toxicity*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D007986:Luteinizing Hormone / Q000097:blood*; D008297:Male; D008628:Mercury / Q000097:blood / Q000633:toxicity*; D010902:Pituitary Gland / Q000378:metabolism; D012098:Reproduction / Q000187:drug effects*; D012621:Seasons; D013054:Spectrophotometry, Atomic; D013538:Svalbard; D013739:Testosterone / Q000097:blood
chemical_list: D004785:Environmental Pollutants; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; D008628:Mercury
keywords: GnRH challenge; black-legged kittiwake; intermittent breeding; luteinizing hormone; mercury