International audience | Antarctic marine ecosystems are often considered to be pristine environments, yet wildlife in the polar regions may still be exposed to high levels of environmental contaminants. Here, we measured total mercury (THg) concentrations in blood samples from adult brown skuas Stercorarius antarcticus lonnbergi (n = 82) from three breeding colonies south of the Antarctic Polar Front in the Southern Ocean (southwest Atlantic region): (i) Bahía Esperanza/Hope Bay, Antarctic Peninsula; (ii) Signy Island, South Orkney Islands; and, (iii) Bird Island, South Georgia. Blood THg concentrations increased from the Antarctic Peninsula towards the Antarctic Polar Front, such that Hg contamination was lowest at Bahía Esperanza/Hope Bay (mean ± SD, 0.95 ± 0.45 µg g-1 dw), intermediate at Signy Island (3.42 ± 2.29 µg g-1 dw) and highest at Bird Island (4.47 ± 1.10 µg g-1 dw). Blood THg concentrations also showed a weak positive correlation with δ15N values, likely reflecting the biomagnification process. Males had higher Hg burdens than females, which may reflect deposition of Hg into eggs by females or potentially differences in their trophic ecology. These data provide important insights into intraspecific variation in contamination and the geographic transfer of Hg to seabirds in the Southern Ocean.

Antarctic marine ecosystems are often considered to be pristine environments, yet wildlife in the polar regions may still be exposed to high levels of environmental contaminants. Here, we measured total mercury (THg) concentrations in blood samples from adult brown skuas Stercorarius antarcticus lonnbergi (n = 82) from three breeding colonies south of the Antarctic Polar Front in the Southern Ocean (southwest Atlantic region): (i) Bahía Esperanza/Hope Bay, Antarctic Peninsula; (ii) Signy Island, South Orkney Islands; and, (iii) Bird Island, South Georgia. Blood THg concentrations increased from the Antarctic Peninsula towards the Antarctic Polar Front, such that Hg contamination was lowest at Bahía Esperanza/Hope Bay (mean ± SD, 0.95 ± 0.45 μg g⁻¹ dw), intermediate at Signy Island (3.42 ± 2.29 μg g⁻¹ dw) and highest at Bird Island (4.47 ± 1.10 μg g⁻¹ dw). Blood THg concentrations also showed a weak positive correlation with δ¹⁵N values, likely reflecting the biomagnification process. Males had higher Hg burdens than females, which may reflect deposition of Hg into eggs by females or potentially differences in their trophic ecology. These data provide important insights into intraspecific variation in contamination and the geographic transfer of Hg to seabirds in the Southern Ocean.

International audience | Mercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments.

Mercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments.

International audience | Mercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments.

International audience | Albatrosses (Diomedeidae) are iconic pelagic seabirds whose life-history traits (longevity, high trophic position) put them at risk of high levels of exposure to methylmercury (MeHg), a powerful neurotoxin that threatens humans and wildlife. Here, we report total Hg (THg) concentrations in body feathers from 516 individual albatrosses from 35 populations, including all 20 taxa breeding in the Southern Ocean. Our key finding is that albatrosses constitute the family of birds with the highest levels of contamination by Hg, with mean feather THg concentrations in different populations ranging from moderate (3.8 mg/g) to exceptionally high (34.6 mg/g). Phylogeny had a significant effect on feather THg concentrations, with the mean decreasing in the order Diomedea > Phoebetria > Thalassarche. Unexpectedly, moulting habitats (reflected in feather d13C values) was the main driver of feather THg concentrations, indicating increasing MeHg exposure with decreasing latitude, from Antarctic to subtropical waters. The role of moulting habitat suggests that the majority of MeHg eliminated into feathers by albatrosses is from recent food intake (income strategy). They thus differ from species that depurate MeHg into feathers that has been accumulated in internal tissues between two successive moults (capital strategy). Since albatrosses are amongst the most threatened families of birds, it is noteworthy that two albatrosses listed as Critical by the World Conservation Union (IUCN) that moult and breed in temperate waters are the most Hg-contaminated species (the Amsterdam and Tristan albatrosses). These data emphasize the urgent need for robust assessment of the impact of Hg contamination on the biology of albatrosses and they docu-ment the high MeHg level exposure of wildlife living in the most remote marine areas on Earth.

Albatrosses (Diomedeidae) are iconic pelagic seabirds whose life-history traits (longevity, high trophic position) put them at risk of high levels of exposure to methylmercury (MeHg), a powerful neurotoxin that threatens humans and wildlife. Here, we report total Hg (THg) concentrations in body feathers from 516 individual albatrosses from 35 populations, including all 20 taxa breeding in the Southern Ocean. Our key finding is that albatrosses constitute the family of birds with the highest levels of contamination by Hg, with mean feather THg concentrations in different populations ranging from moderate (3.8 μg/g) to exceptionally high (34.6 μg/g). Phylogeny had a significant effect on feather THg concentrations, with the mean decreasing in the order Diomedea > Phoebetria > Thalassarche. Unexpectedly, moulting habitats (reflected in feather δ13C values) was the main driver of feather THg concentrations, indicating increasing MeHg exposure with decreasing latitude, from Antarctic to subtropical waters. The role of moulting habitat suggests that the majority of MeHg eliminated into feathers by albatrosses is from recent food intake (income strategy). They thus differ from species that depurate MeHg into feathers that has been accumulated in internal tissues between two successive moults (capital strategy). Since albatrosses are amongst the most threatened families of birds, it is noteworthy that two albatrosses listed as Critical by the World Conservation Union (IUCN) that moult and breed in temperate waters are the most Hg-contaminated species (the Amsterdam and Tristan albatrosses). These data emphasize the urgent need for robust assessment of the impact of Hg contamination on the biology of albatrosses and they document the high MeHg level exposure of wildlife living in the most remote marine areas on Earth.

International audience | Mercury (Hg) is a pervasive contaminant reaching Antarctic environments through atmospheric transport and deposition. Seabirds as meso to top predators can accumulate high quantities of Hg through diet. Reproduction is one of the most sensitive endpoints of Hg toxicity in marine birds. Yet, few studies have explored Hg exposure and effects in Antarctic seabirds, where increasing environmental perturbations challenge animal populations. This study focuses on the Antarctic petrel Thalassoica antarctica from Svarthamaren, Antarctica, where the world's largest breeding population is thought to be in decline. Hg and the stable isotopes of carbon (δ13C, proxy of feeding habitat) and nitrogen (δ15N, trophic position/diet) were measured in red blood cells from 266 individuals over two breeding years (2012–13, 2013–14). Our aims were to 1) quantify the influence of individual traits (size and sex) and feeding ecology (foraging location, δ13C and δ15N values) on Hg exposure, and 2) test the relationship between Hg concentrations with body condition and breeding output (hatching success and chick survival). Hg concentrations in Antarctic petrels (mean ± SD, 0.84 ± 0.25, min-max, 0.42–2.71 μg g−1 dw) were relatively low when compared to other Antarctic seabirds. Hg concentrations increased significantly with δ15N values, indicating that individuals with a higher trophic level (i.e. feeding more on fish) had higher Hg exposure. By contrast, Hg exposure was not driven by feeding habitat (inferred from both foraging location and δ13C values), suggesting that Hg transfer to predators in Antarctic waters is relatively homogeneous over a large geographical scale. Hg concentrations were not related to body condition, hatching date and short-term breeding output. At present, Hg exposure is likely not of concern for this population. Nevertheless, further studies on other fitness parameters and long-term breeding output are warranted because Hg can have long-term population-level effects without consequences on current breeding success.

Mercury (Hg) is a pervasive contaminant reaching Antarctic environments through atmospheric transport and deposition. Seabirds as meso to top predators can accumulate high quantities of Hg through diet. Reproduction is one of the most sensitive endpoints of Hg toxicity in marine birds. Yet, few studies have explored Hg exposure and effects in Antarctic seabirds, where increasing environmental perturbations challenge animal populations. This study focuses on the Antarctic petrel Thalassoica antarctica from Svarthamaren, Antarctica, where the world's largest breeding population is thought to be in decline. Hg and the stable isotopes of carbon (δ13C, proxy of feeding habitat) and nitrogen (δ15N, trophic position/diet) were measured in red blood cells from 266 individuals over two breeding years (2012–13, 2013–14). Our aims were to 1) quantify the influence of individual traits (size and sex) and feeding ecology (foraging location, δ13C and δ15N values) on Hg exposure, and 2) test the relationship between Hg concentrations with body condition and breeding output (hatching success and chick survival). Hg concentrations in Antarctic petrels (mean ± SD, 0.84 ± 0.25, min-max, 0.42–2.71 μg g−1 dw) were relatively low when compared to other Antarctic seabirds. Hg concentrations increased significantly with δ15N values, indicating that individuals with a higher trophic level (i.e. feeding more on fish) had higher Hg exposure. By contrast, Hg exposure was not driven by feeding habitat (inferred from both foraging location and δ13C values), suggesting that Hg transfer to predators in Antarctic waters is relatively homogeneous over a large geographical scale. Hg concentrations were not related to body condition, hatching date and short-term breeding output. At present, Hg exposure is likely not of concern for this population. Nevertheless, further studies on other fitness parameters and long-term breeding output are warranted because Hg can have long-term population-level effects without consequences on current breeding success.

International audience | Seabirds integrate bioaccumulative contaminants via food intake and have revealed geographical trends of contamination in a variety of ecosystems. Pre-fledging seabird chicks are particularly interesting as bioindicators of chemical contamination, because concentrations in their tissues reflect primarily dietary sources from the local environment. Here we measured 14 trace elements and 18 persistent organic pollutants (POPs) in blood of chicks of skuas that breed in four sites encompassing a large latitudinal range within the southern Indian Ocean, from Antarctica (Adélie Land, south polar skua Catharacta maccormicki), through subantarctic areas (Crozet and Kerguelen Islands, brown skua C. lonnbergi), to the subtropics (Amsterdam Island, C. lonnbergi). Stables isotopes of carbon (δ13C, feeding habitat) and nitrogen (δ15N, trophic position) were also measured to control for the influence of feeding habits on contaminant burdens. Concentrations of mercury (Hg) and selenium (Se) were very high at all the four sites, with Amsterdam birds having the highest concentrations ever reported in chicks worldwide (4.0 ± 0.8 and 646 ± 123 µg g-1 dry weight, respectively). Blood Hg concentrations showed a clear latitudinal pattern, increasing from chicks in Antarctica to chicks in the subantarctic and subtropical islands. Interestingly, blood Se concentrations showed similar between-population differences to Hg, suggesting its involvement in protective mechanisms against Hg toxicity. Chicks’ POPs pattern was largely dominated by organochlorine pesticides, in particular DDT metabolites and hexachlorobenzene (HCB). Skua chicks from subantarctic islands presented high concentrations and diversity of POPs. By contrast, chicks from the Antarctic site overall had the lowest concentrations and diversity of both metallic and organic contaminants, with the exception of HCB and arsenic. Skua populations from these sites, being naturally exposed to different quantities of contaminants, are potentially good models for testing toxic effects in developing chicks in the wild.

Seabirds integrate bioaccumulative contaminants via food intake and have revealed geographical trends of contamination in a variety of ecosystems. Pre-fledging seabird chicks are particularly interesting as bioindicators of chemical contamination, because concentrations in their tissues reflect primarily dietary sources from the local environment. Here we measured 14 trace elements and 18 persistent organic pollutants (POPs) in blood of chicks of skuas that breed in four sites encompassing a large latitudinal range within the southern Indian Ocean, from Antarctica (Adélie Land, south polar skua Catharacta maccormicki), through subantarctic areas (Crozet and Kerguelen Islands, brown skua C. lonnbergi), to the subtropics (Amsterdam Island, C. lonnbergi). Stables isotopes of carbon (δ13C, feeding habitat) and nitrogen (δ15N, trophic position) were also measured to control for the influence of feeding habits on contaminant burdens. Concentrations of mercury (Hg) and selenium (Se) were very high at all the four sites, with Amsterdam birds having the highest concentrations ever reported in chicks worldwide (4.0 ± 0.8 and 646 ± 123 μg g−1 dry weight, respectively). Blood Hg concentrations showed a clear latitudinal pattern, increasing from chicks in Antarctica to chicks in the subantarctic and subtropical islands. Interestingly, blood Se concentrations showed similar between-population differences to Hg, suggesting its involvement in protective mechanisms against Hg toxicity. Chicks’ POPs pattern was largely dominated by organochlorine pesticides, in particular DDT metabolites and hexachlorobenzene (HCB). Skua chicks from subantarctic islands presented high concentrations and diversity of POPs. By contrast, chicks from the Antarctic site overall had the lowest concentrations and diversity of both metallic and organic contaminants, with the exception of HCB and arsenic. Skua populations from these sites, being naturally exposed to different quantities of contaminants, are potentially good models for testing toxic effects in developing chicks in the wild.