HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Variation in blood mercury concentrations in brown skuas (Stercorarius antarcticus) is related to trophic ecology but not breeding success or adult body condition
In central-place foragers the breeding cycle is often the period with the highest energy cost, wh... more In central-place foragers the breeding cycle is often the period with the highest energy cost, where dietary and stored lipids play a key role. Lipids are mobilized through blood lipoproteins providing fuel to tissues. Thus, the use of food and endogenous resources with high-energy fats is important to sustain individuals' nutritional demands. To evaluate the physiological components associated to energetic demands and their variation regarding life history processes, we analysed the plasma circulating lipoprotein levels, the lipid classes and fatty acid (FA) composition in Brown Skua (Stercorarius antarcticus lonnbergi) in breeding stages with different energy requirements: incubation (In), early rearing (Er) and late rearing (Lr). We expected to find differences according to the energy demands of each stage and the sex. The level of Very Low Density lipoproteins was affected by the sex and the breeding stage, whereas Low Density lipoproteins only by the stage. Total plasma lipid content and circulating lipid classes were invariant among the stages studied; however, differences in total plasma FA and monounsaturated FA (oleic and nervonic) abundances were observed among stages. Besides, a decrease in the n-3:n-6 ratio was observed towards the Lr stage. The differences found in lipoproteins may be linked to changes in the energy demands throughout the breeding period. Moreover, the variation observed in FA abundance and n-3:n-6 ratio may be related to a preferential mobilization of FA from stores as fuel or, possibly, to a differential use of the available food resources.
Antarctic marine ecosystems are often considered to be pristine environments, yet wildlife in the... more 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 δ 15 N 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. ☆ This paper has been recommended for acceptance by Wen-Xiong Wang.
El skúa pardo, Stercorarius antarcticus, es un depredador oportunista que se alimenta de recursos... more El skúa pardo, Stercorarius antarcticus, es un depredador oportunista que se alimenta de recursos terrestres
The capacity of seabirds to shape their physiological and immune phenotypes may often be constrai... more The capacity of seabirds to shape their physiological and immune phenotypes may often be constrained by the ecological context. While phenotypic plasticity in physiological traits has been previously studied, the molecular mechanisms underlying phenotype plasticity in response to environmental stress have been little explored. This prompted us to enquire about how the nutritional and immune status are involved in physiological adaptations in breeding seabirds under anthropogenic pressure. At Esperanza (Hope) Bay, Antarctic Peninsula exists one of the biggest breeding penguin colony of Pygoscelis adeliae (Adélie). At this location, penguins nest nearby the Argentinian Esperanza Station and, therefore, are exposed to high levels of disturbance, whereas there is a low disturbed area, where penguins also breed far away from the Station. In both areas, the nutritional and immune status in breeding individuals was addressed and serum protein expression level was analyzed using a proteomic approach. Body mass, proteins, albumin, and triacylglycerol were higher in penguins from the low disturbance area, whereas uric acid increased in individuals from the disturbed area, indicating a poorer body condition of penguins under anthropogenic pressure. Immune responses were elevated in penguins from the disturbed area (IgY, γ-globulins and hemagglutinating activity). Finally, individuals breeding under anthropogenic pressure overexpressed proteins with immune, antioxidant, and metabolic functions. The poor nutritional status of penguins under disturbance may be the consequence of the reallocation of resources to the immune system. Altogether, this would constitute a potential strategy to preserve an adequate immune phenotype under stressed environments.
In central-place foragers the breeding cycle is often the period with the highest energy cost, wh... more In central-place foragers the breeding cycle is often the period with the highest energy cost, where dietary and stored lipids play a key role. Lipids are mobilized through blood lipoproteins providing fuel to tissues. Thus, the use of food and endogenous resources with high-energy fats is important to sustain individuals' nutritional demands. To evaluate the physiological components associated to energetic demands and their variation regarding life history processes, we analysed the plasma circulating lipoprotein levels, the lipid classes and fatty acid (FA) composition in Brown Skua (Stercorarius antarcticus lonnbergi) in breeding stages with different energy requirements: incubation (In), early rearing (Er) and late rearing (Lr). We expected to find differences according to the energy demands of each stage and the sex. The level of Very Low Density lipoproteins was affected by the sex and the breeding stage, whereas Low Density lipoproteins only by the stage. Total plasma lipid content and circulating lipid classes were invariant among the stages studied; however, differences in total plasma FA and monounsaturated FA (oleic and nervonic) abundances were observed among stages. Besides, a decrease in the n-3:n-6 ratio was observed towards the Lr stage. The differences found in lipoproteins may be linked to changes in the energy demands throughout the breeding period. Moreover, the variation observed in FA abundance and n-3:n-6 ratio may be related to a preferential mobilization of FA from stores as fuel or, possibly, to a differential use of the available food resources.
During the last decades plastic pollution has become a common issue in marine environments. Studi... more During the last decades plastic pollution has become a common issue in marine environments. Studies on seabirds have focused on species that ingest plastics mistaken for prey or indirectly through their preferred prey or, on how foraging strategy influences this behaviour. We evaluated plastic ingestion in relation to the proximity of nests to areas with different anthropogenic pressure, breeding status and breeding stage. We analyzed regurgitated pellets (n = 1001) from a seabird, the Brown Skua (Stercorarius antarcticus lonnbergi) at Esperanza/Hope Bay, Antarctic Peninsula. Plastics were found in 9% of pellets, only in breeders from an area with high antropogenic activity. The prevalence of plastic increased during the brooding of chicks stage, when skuas expand their feeding niche. Our results support previous work which demonstrated that seabirds with wider feeding niche show higher loads of plastics. Altogether, this provides insights into the dynamics of plastic transfer within the environment.
Breeding has a high energetic cost and, in central place foragers, also restricts the ability of ... more Breeding has a high energetic cost and, in central place foragers, also restricts the ability of parents for self-foraging, with affecting on their body and immunological conditions. In migratory species, breeding overlaps the period of recovery of body conditions before the following outbound migration. Those factors may reduce the breeding success and even lead parents to abandon their offspring if parental body condition cannot guarantee the success of the next migration. We studied the body and immunological conditions of a low breeding success population of Brown Skuas (Stercorarius antarcticus lonnbergi) throughout their breeding season. We evaluated changes in their body mass, blood parameters and heterophil:lymphocyte ratios (H:L), at three stages of their breeding period: Incubation, Early rearing and Late rearing. The body mass of female Brown skuas decreased during the initial stages of the breeding period and recovered towards the end. The changes in metabolites suggest a use of protein body reserves but not of lipid reserves. The H:L ratio did not indicate changes in the immune condition of the birds. Our results suggest that this low breeding success population begins its breeding period with a poor body condition that it continues to decline throughout the season. Those poor body conditions added to the need for recovery for the next migration may be the cause of the abandonment of almost totally feathered chicks. Our evidence highlights the importance of food availability, in either the breeding or wintering sites, or both, on the health of the populations of migratory top predators.
Top predators exhibit a critical role in ecosystem functioning and in the stability of the food w... more Top predators exhibit a critical role in ecosystem functioning and in the stability of the food web, so research on diet is relevant to understand their foraging behavior. Seasonal variation in diet and prey selection may be the result of fluctuations in the physiological demands during the different annual life cycles, and ecological factors such as resource availability, which may influence the foraging behavior. Moreover, the competition for the feeding territories between conspecifics in a population or with other predators may also lead to diversification of the diet. In this work, we determined the diet of breeding and non-breeding Brown Skuas (Stercorarius antarcticus lonnbergi) at Hope Bay, Antarctic Peninsula, to understand prey selection and the feeding habits of groups with different physiological and energy demands. To assess the breeders' diet, 204 pellets were collected near the nests, while for non-breeders, 330 pellets were obtained from different areas where they usually group, and prey items were determined. Pellet dimensions were larger in non-breeding skuas. Breeding skuas' pellets showed a higher content of energy-rich items such as penguin eggs, fishes and molluscs, while in non-breeding skuas, pellets consisted mainly of penguin feathers and bones. The differences in diet between the groups may be a consequence of the supplementation of the food obtained on land by traveling to the ocean by breeding skuas, in order to compensate the energetic demands during reproduction. Our results highlight differences in the feeding habits and prey selection, as well as a variation in the flexibility of the foraging strategy of both groups.
During breeding, Brown Skuas (Stercorarius antarcticus lonnbergi) perform a great physical effort... more During breeding, Brown Skuas (Stercorarius antarcticus lonnbergi) perform a great physical effort in the care and maintenance of the nest. Interestingly, the breeding colony on which this work was conducted is in steady decline in recent years. In order to understand the physiological background responsible for the trade off between reproductive effort and health status, in adults and the possible reasons for the colony decline, we evaluated the health status in Brown Skuas parents and growing chicks and blood samples were obtained in three different breeding stages from adults: In (incubation), Er (after egg hatching), and Lr (during chick rearing) and from developing chicks. Serum albumin, α-, β-. and γ-globulin fractions, IgY level and corticosterone were determined in adults, while plasma proteins concentration, electrolytes, and γ-globulins were determined in chicks. Differences in albumin, α-, and γ-globulins and IgY levels were observed in adults through the reproductive stages, indicating a decline in nutritional status and immunocompetence during breeding. In addition, a decline in body condition and immune status was observed in growing chicks, indicating a close relationship between the decrease of the health status and reproductive effort performed by adults and the physiological status of the nestlings during development.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
It is established that haematological and biochemical parameters provide important data to assess... more It is established that haematological and biochemical parameters provide important data to assess the physiological condition and health status of wild birds. To undertake conservation physiology or ecophysiology work, it is therefore essential to establish baseline physiological parameters and how these parameters change with age and life history events. In this work, we determined and compared baseline haematology and serum biochemistry between adults and chicks of three Antarctic penguin species of the genus Pygoscelis: gentoo (P. papua), Adé lie (P. adeliae) and chinstrap (P. antarcticus). Differences in adults among species were observed in haemoglobin and biochemical parameters such as total proteins, glucose and alkaline phosphatase activity. In addition, differences between adults and chicks in haematocrit, haemoglobin, total proteins and glucose concentration were determined. Moreover, we evaluated the electrophoretic protein profiles between adults and chicks of the genus Pygoscelis, and a conserved protein pattern was observed among species and ages in the genus. Altogether, the results suggest that biochemical and haematological differences among pygoscelids may be related to the nutritional status and energetic expenditure during breeding as well as their feeding habits and development stage.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Variation in blood mercury concentrations in brown skuas (Stercorarius antarcticus) is related to trophic ecology but not breeding success or adult body condition
In central-place foragers the breeding cycle is often the period with the highest energy cost, wh... more In central-place foragers the breeding cycle is often the period with the highest energy cost, where dietary and stored lipids play a key role. Lipids are mobilized through blood lipoproteins providing fuel to tissues. Thus, the use of food and endogenous resources with high-energy fats is important to sustain individuals' nutritional demands. To evaluate the physiological components associated to energetic demands and their variation regarding life history processes, we analysed the plasma circulating lipoprotein levels, the lipid classes and fatty acid (FA) composition in Brown Skua (Stercorarius antarcticus lonnbergi) in breeding stages with different energy requirements: incubation (In), early rearing (Er) and late rearing (Lr). We expected to find differences according to the energy demands of each stage and the sex. The level of Very Low Density lipoproteins was affected by the sex and the breeding stage, whereas Low Density lipoproteins only by the stage. Total plasma lipid content and circulating lipid classes were invariant among the stages studied; however, differences in total plasma FA and monounsaturated FA (oleic and nervonic) abundances were observed among stages. Besides, a decrease in the n-3:n-6 ratio was observed towards the Lr stage. The differences found in lipoproteins may be linked to changes in the energy demands throughout the breeding period. Moreover, the variation observed in FA abundance and n-3:n-6 ratio may be related to a preferential mobilization of FA from stores as fuel or, possibly, to a differential use of the available food resources.
Antarctic marine ecosystems are often considered to be pristine environments, yet wildlife in the... more 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 δ 15 N 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. ☆ This paper has been recommended for acceptance by Wen-Xiong Wang.
El skúa pardo, Stercorarius antarcticus, es un depredador oportunista que se alimenta de recursos... more El skúa pardo, Stercorarius antarcticus, es un depredador oportunista que se alimenta de recursos terrestres
The capacity of seabirds to shape their physiological and immune phenotypes may often be constrai... more The capacity of seabirds to shape their physiological and immune phenotypes may often be constrained by the ecological context. While phenotypic plasticity in physiological traits has been previously studied, the molecular mechanisms underlying phenotype plasticity in response to environmental stress have been little explored. This prompted us to enquire about how the nutritional and immune status are involved in physiological adaptations in breeding seabirds under anthropogenic pressure. At Esperanza (Hope) Bay, Antarctic Peninsula exists one of the biggest breeding penguin colony of Pygoscelis adeliae (Adélie). At this location, penguins nest nearby the Argentinian Esperanza Station and, therefore, are exposed to high levels of disturbance, whereas there is a low disturbed area, where penguins also breed far away from the Station. In both areas, the nutritional and immune status in breeding individuals was addressed and serum protein expression level was analyzed using a proteomic approach. Body mass, proteins, albumin, and triacylglycerol were higher in penguins from the low disturbance area, whereas uric acid increased in individuals from the disturbed area, indicating a poorer body condition of penguins under anthropogenic pressure. Immune responses were elevated in penguins from the disturbed area (IgY, γ-globulins and hemagglutinating activity). Finally, individuals breeding under anthropogenic pressure overexpressed proteins with immune, antioxidant, and metabolic functions. The poor nutritional status of penguins under disturbance may be the consequence of the reallocation of resources to the immune system. Altogether, this would constitute a potential strategy to preserve an adequate immune phenotype under stressed environments.
In central-place foragers the breeding cycle is often the period with the highest energy cost, wh... more In central-place foragers the breeding cycle is often the period with the highest energy cost, where dietary and stored lipids play a key role. Lipids are mobilized through blood lipoproteins providing fuel to tissues. Thus, the use of food and endogenous resources with high-energy fats is important to sustain individuals' nutritional demands. To evaluate the physiological components associated to energetic demands and their variation regarding life history processes, we analysed the plasma circulating lipoprotein levels, the lipid classes and fatty acid (FA) composition in Brown Skua (Stercorarius antarcticus lonnbergi) in breeding stages with different energy requirements: incubation (In), early rearing (Er) and late rearing (Lr). We expected to find differences according to the energy demands of each stage and the sex. The level of Very Low Density lipoproteins was affected by the sex and the breeding stage, whereas Low Density lipoproteins only by the stage. Total plasma lipid content and circulating lipid classes were invariant among the stages studied; however, differences in total plasma FA and monounsaturated FA (oleic and nervonic) abundances were observed among stages. Besides, a decrease in the n-3:n-6 ratio was observed towards the Lr stage. The differences found in lipoproteins may be linked to changes in the energy demands throughout the breeding period. Moreover, the variation observed in FA abundance and n-3:n-6 ratio may be related to a preferential mobilization of FA from stores as fuel or, possibly, to a differential use of the available food resources.
During the last decades plastic pollution has become a common issue in marine environments. Studi... more During the last decades plastic pollution has become a common issue in marine environments. Studies on seabirds have focused on species that ingest plastics mistaken for prey or indirectly through their preferred prey or, on how foraging strategy influences this behaviour. We evaluated plastic ingestion in relation to the proximity of nests to areas with different anthropogenic pressure, breeding status and breeding stage. We analyzed regurgitated pellets (n = 1001) from a seabird, the Brown Skua (Stercorarius antarcticus lonnbergi) at Esperanza/Hope Bay, Antarctic Peninsula. Plastics were found in 9% of pellets, only in breeders from an area with high antropogenic activity. The prevalence of plastic increased during the brooding of chicks stage, when skuas expand their feeding niche. Our results support previous work which demonstrated that seabirds with wider feeding niche show higher loads of plastics. Altogether, this provides insights into the dynamics of plastic transfer within the environment.
Breeding has a high energetic cost and, in central place foragers, also restricts the ability of ... more Breeding has a high energetic cost and, in central place foragers, also restricts the ability of parents for self-foraging, with affecting on their body and immunological conditions. In migratory species, breeding overlaps the period of recovery of body conditions before the following outbound migration. Those factors may reduce the breeding success and even lead parents to abandon their offspring if parental body condition cannot guarantee the success of the next migration. We studied the body and immunological conditions of a low breeding success population of Brown Skuas (Stercorarius antarcticus lonnbergi) throughout their breeding season. We evaluated changes in their body mass, blood parameters and heterophil:lymphocyte ratios (H:L), at three stages of their breeding period: Incubation, Early rearing and Late rearing. The body mass of female Brown skuas decreased during the initial stages of the breeding period and recovered towards the end. The changes in metabolites suggest a use of protein body reserves but not of lipid reserves. The H:L ratio did not indicate changes in the immune condition of the birds. Our results suggest that this low breeding success population begins its breeding period with a poor body condition that it continues to decline throughout the season. Those poor body conditions added to the need for recovery for the next migration may be the cause of the abandonment of almost totally feathered chicks. Our evidence highlights the importance of food availability, in either the breeding or wintering sites, or both, on the health of the populations of migratory top predators.
Top predators exhibit a critical role in ecosystem functioning and in the stability of the food w... more Top predators exhibit a critical role in ecosystem functioning and in the stability of the food web, so research on diet is relevant to understand their foraging behavior. Seasonal variation in diet and prey selection may be the result of fluctuations in the physiological demands during the different annual life cycles, and ecological factors such as resource availability, which may influence the foraging behavior. Moreover, the competition for the feeding territories between conspecifics in a population or with other predators may also lead to diversification of the diet. In this work, we determined the diet of breeding and non-breeding Brown Skuas (Stercorarius antarcticus lonnbergi) at Hope Bay, Antarctic Peninsula, to understand prey selection and the feeding habits of groups with different physiological and energy demands. To assess the breeders' diet, 204 pellets were collected near the nests, while for non-breeders, 330 pellets were obtained from different areas where they usually group, and prey items were determined. Pellet dimensions were larger in non-breeding skuas. Breeding skuas' pellets showed a higher content of energy-rich items such as penguin eggs, fishes and molluscs, while in non-breeding skuas, pellets consisted mainly of penguin feathers and bones. The differences in diet between the groups may be a consequence of the supplementation of the food obtained on land by traveling to the ocean by breeding skuas, in order to compensate the energetic demands during reproduction. Our results highlight differences in the feeding habits and prey selection, as well as a variation in the flexibility of the foraging strategy of both groups.
During breeding, Brown Skuas (Stercorarius antarcticus lonnbergi) perform a great physical effort... more During breeding, Brown Skuas (Stercorarius antarcticus lonnbergi) perform a great physical effort in the care and maintenance of the nest. Interestingly, the breeding colony on which this work was conducted is in steady decline in recent years. In order to understand the physiological background responsible for the trade off between reproductive effort and health status, in adults and the possible reasons for the colony decline, we evaluated the health status in Brown Skuas parents and growing chicks and blood samples were obtained in three different breeding stages from adults: In (incubation), Er (after egg hatching), and Lr (during chick rearing) and from developing chicks. Serum albumin, α-, β-. and γ-globulin fractions, IgY level and corticosterone were determined in adults, while plasma proteins concentration, electrolytes, and γ-globulins were determined in chicks. Differences in albumin, α-, and γ-globulins and IgY levels were observed in adults through the reproductive stages, indicating a decline in nutritional status and immunocompetence during breeding. In addition, a decline in body condition and immune status was observed in growing chicks, indicating a close relationship between the decrease of the health status and reproductive effort performed by adults and the physiological status of the nestlings during development.
BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.
It is established that haematological and biochemical parameters provide important data to assess... more It is established that haematological and biochemical parameters provide important data to assess the physiological condition and health status of wild birds. To undertake conservation physiology or ecophysiology work, it is therefore essential to establish baseline physiological parameters and how these parameters change with age and life history events. In this work, we determined and compared baseline haematology and serum biochemistry between adults and chicks of three Antarctic penguin species of the genus Pygoscelis: gentoo (P. papua), Adé lie (P. adeliae) and chinstrap (P. antarcticus). Differences in adults among species were observed in haemoglobin and biochemical parameters such as total proteins, glucose and alkaline phosphatase activity. In addition, differences between adults and chicks in haematocrit, haemoglobin, total proteins and glucose concentration were determined. Moreover, we evaluated the electrophoretic protein profiles between adults and chicks of the genus Pygoscelis, and a conserved protein pattern was observed among species and ages in the genus. Altogether, the results suggest that biochemical and haematological differences among pygoscelids may be related to the nutritional status and energetic expenditure during breeding as well as their feeding habits and development stage.
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