Penguins as bioindicators of mercury contamination in the Southern Ocean: Birds from the Kerguelen Islands as a case study

• Published in: Science of The Total Environment
• Main Authors: Carravieri, Alice, Bustamante, Paco, Churlaud, Carine, Cherel, Yves
• Other Authors: LIttoral ENvironnement et Sociétés - UMRi 7266 (LIENSs), Université de La Rochelle (ULR)-Centre National de la Recherche Scientifique (CNRS), Centre d'études biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: stable isotopes; Antarctica; Indian Ocean; seabird; trace element; metal; [SDV.TOX.ECO]Life Sciences [q-bio]/Toxicology/Ecotoxicology; Antarctic; Indian; Kerguelen; Kerguelen Islands; Southern Ocean; Antarc*
• Online Access: https://hal.archives-ouvertes.fr/hal-00805466; https://hal.archives-ouvertes.fr/hal-00805466/document; https://hal.archives-ouvertes.fr/hal-00805466/file/Carravieri_et_al._2013_STOTEN.pdf; https://doi.org/10.1016/j.scitotenv.2013.02.060

International audience Seabirds have been used extensively as bioindicators of mercury (Hg) contamination in the marine environment, although information on flightless species like penguins remains limited. In order to assess the use of penguins as bioindicators of Hg contamination in subantarctic and Antarctic marine ecosystems, Hg concentrations were evaluated in the feathers of the four species that breed on the Kerguelen Islands in the southern Indian Ocean. Compared to other seabirds, adult Kerguelen penguins had low to moderate feather Hg concentrations, with an average ranging from 1.96 ± 0.41 µg∙g-1 dry weight in the southern rockhopper to 5.85 ± 3.00 µg∙g-1 dry weight in gentoo penguins. The species was a major determinant of Hg contamination, with feather Hg concentrations being lower in the oceanic species (king and crested penguins) than in the coastal ones (gentoo penguins). In all species however, feather Hg concentrations were higher in adults than in chicks, reflecting the different periods of Hg bioaccumulation in the internal tissues of the two age classes. The relationship between adult penguin trophic ecology and Hg burdens was investigated using stable isotopes. Feeding habits (reflected by δ15N values) had a greater effect on adult feather Hg concentrations when compared to foraging habitats (reflected by δ13C values), indicating Hg biomagnification in Kerguelen neritic and oceanic waters. Dietary preferences were crucial in explaining individual feather Hg concentrations, as highlighted by intra-specific variation in Hg levels of gentoo penguins sampled at two different breeding sites of the Archipelago. Penguins appear to reflect Hg bioavailability reliably in their foraging environment and could serve as efficient bioindicators of Hg contamination in the Southern Ocean on different spatial and temporal scales.