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High levels of environmental contaminants such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and mercury (Hg) have been reported in some Arctic top predators such as seabirds. Chronic exposure to these contaminants might alter the response to environmental changes through interference with the regulation of corticosterone (CORT), a glucocorticoid stress hormone released by the hypothalamo-pituitary-adrenal (HPA) axis. Positive and negative relationships between CORT and environmental contaminants have been reported in polar seabirds. However, patterns appear inconclusive and it is difficult to attribute these relationships to a dysfunction of the HPA axis or to other confounding effects. In order to explore the relationships between the HPA axis activity and contaminants, we tested whether different aspects of the HPA axis of an Arctic seabird, the black-legged kittiwakes Rissa tridactyla, would be related to blood Hg, PCB and OCP concentrations. Male kittiwakes were caught during the incubation period in Svalbard and were subjected to different stress series: (1) a capture-restraint stress protocol, (2) an injection of dexamethasone (DEX) that enabled to test the efficacy of the HPA negative feedback and (3) an injection of adrenocorticotropic hormone (ACTH) that informed on the adrenal responsiveness. The HPA axis activity was unrelated to ΣOCPs and Hg. However, birds with high concentrations of ΣPCBs released more CORT after the ACTH injection. It is suggested that ΣPCBs may increase the number of ACTH-receptors on the adrenals. Additionally, hatching date was delayed in males with higher concentrations of ΣPCBs and ΣOCPs. This study gives new evidence that PCBs and adrenal activity may be related. Thus high PCB burden may make individuals more prone to other stressors such as ongoing climate change., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Increasing levels of poly- and perfluorinated alkyl substances (PFASs) have recently been described in Arctic biota. These emerging substances are of concern given their resistance to degradation and metabolization. Some studies have reported endocrine disrupting effects for some PFASs. However, there is a gap of knowledge on the potential relationships between PFASs and hormones mediating the life-history trade-off between reproduction and survival, such as glucocorticoids. The aims of this study were to (1) describe the concentrations of plasma perfluoroalkyl sulfonates and perfluoroalkyl carboxylates in Svalbard black-legged kittiwakes (Rissa tridactyla) in relation to gender and body-condition, (2) explore the relationships between PFASs and corticosterone (the major glucocorticoid in birds), and (3) assess the consequences of PFAS exposure for reproductive success. Perfluorononanoate was positively related to body-condition in male kittiwakes; perfluorotridecanoate and perfluorotetradecanoate to decreased baseline corticosterone in both sexes; and perfluorododecanoate was related to lower hatching success. These results underline the importance of considering each compound separately when investigating the hazardous effects of PFASs on wildlife.

In seasonal environments, the fitness of animals depends upon the successful integration of life‐history stages throughout their annual cycle. Failing to do so can lead to negative carry‐over effects where individuals are transitioning into the next season in different states, consequently affecting their future performance. However, carry‐over effects can be masked by individual quality when individuals vary in their efficiency at acquiring resources year after year (i.e. 'quality'), leading to cross‐seasonal consistency in individual performance.Here we investigated the relative importance of carry‐over effects and individual quality in determining cross‐seasonal interactions and consequences for breeding success over the full annual cycle of a migratory seabird (black‐legged kittiwake Rissa tridactyla).We monitored the reproduction and annual movement of kittiwakes over 13 years using geolocators to estimate their breeding success, distribution and winter energy expenditure. We combined this with an experimental approach (clutch removal experiment, 2 years) to manipulate the reproductive effort irrespective of individual quality.Piecewise path analyses showed that successful breeders reproduced earlier and were more likely to breed successfully again the following year. This positive interaction among consecutive breeding stages disappeared after controlling for individual quality, suggesting that quality was dominant in determining seasonal interactions. Moreover, controlling experimentally for individual quality revealed underlying carry‐over effects that were otherwise masked by quality, with breeding costs paid in higher energy expenditure and delayed onset of reproduction.We highlight the need to combine an experimental approach along with long‐term data while assessing apparent carry‐over effects in wild animals, and their potential impact on fitness and population demography. [ABSTRACT FROM AUTHOR]

Life-history theory predicts that long-lived organisms should reduce parental effort under inclement environmental conditions in order to favour long-term survival., Seabirds are long-lived top predators often exposed to environmental endocrine disrupting chemicals such as mercury (Hg). Hg-contaminated birds show disrupted parental behaviour., Avian parental behaviour is governed by two key hormones in birds: corticosterone ( CORT, a glucocorticoid hormone) and prolactin ( PRL, a pituitary hormone involved in parental care). Any disruption of these hormones may alter the ability of an individual to adjust parental behaviour to environmental conditions., The first aim of this study was to describe the relationships between blood Hg concentrations, plasma PRL and reproductive performance in Arctic black-legged kittiwakes ( Rissa tridactyla). We a found negative relationship between plasma initial PRL and blood Hg concentrations in males. Moreover, Hg concentration was negatively related to breeding success in chick-rearing males., Secondly, to study the effect of a chronic increase in CORT levels on the Hg- PRL relationship, we experimentally increased stress with CORT pellet implantation. We predicted that Hg and CORT would act synergistically on PRL and an increase in CORT concentration would steepen the Hg- PRL relationship. However, adding CORT did not steepen the Hg- PRL relationship. Hatching success was significantly lower in CORT-implanted males than in controls, and breeding success was not reduced in CORT-implanted male kittiwakes with high levels of blood Hg., Our results suggest that Hg may impair reproductive performance through a disruption of PRL secretion. Contrary to our prediction, Hg and CORT did not act synergistically and the underlying mechanisms associating CORT and Hg with PRL might be more complex than a single interaction between two factors. [ABSTRACT FROM AUTHOR]

• Prolactin levels were positively related to egg angular change in female kittiwakes. • Corticosterone levels were not related to egg-turning behaviors in kittiwakes. • PFASs were positively related to prolactin levels in female kittiwakes. • PFASs were positively related to egg-turning frequency/ angular change in both sexes. • PCBs were negatively related to egg angular change in female kittiwakes. Incubating eggs represents a trade-off for parent birds between spending enough time fasting to take care of the clutch and to get enough nutrients for self-maintenance. It is believed that the pituitary hormone prolactin plays an important role in such allocation processes. Incubation does not solely imply the active warming of the eggs but also the active egg-turning to facilitate absorption of albumen by the embryo, reduce malposition and prevent the embryo from adhering to the inner shell membrane. However, how prolactin secretion is related to egg-turning behaviors is presently poorly addressed. In addition, several environmental contaminants can affect parental care behaviors through their endocrine disrupting properties but the effects of such contaminants on egg-turning behaviors remain so far unexplored. Using artificial eggs equipped with miniaturized data loggers, we investigated the relationships between egg-turning behaviors, prolactin secretion and contaminants burden in Arctic black-legged kittiwakes (Rissa tridactyla). Specifically, we examined the relationships between blood concentrations of poly- and perfluoroalkyl substances (PFASs), organochlorines (OCs), mercury (Hg), plasma prolactin levels and both egg-turning frequency and angular change. We also incorporated baseline corticosterone levels since this glucocorticoid is known to affect parental care. Plasma prolactin levels were positively related to angular change in female kittiwakes while corticosterone was not related to egg-turning behaviors in either sex. Hg was not related to egg-turning behaviors in either sex. We found contrasting associations between OCs and PFASs, since polychlorinated biphenyls (PCBs) were negatively associated with angular change in females, contrary to linear perfluorooctanesulfonate (PFOSlin) and perfluoroalkyl carboxylic acids (PFCAs) which were positively related to egg-turning frequency and angular change in both sexes. Additionally, PFASs concentrations were positively related to prolactin levels in female kittiwake. The possible stimulation of prolactin secretion by PFASs could therefore make adult kittiwakes to allocate more time taking care of their eggs, and thus possibly modify the trade-off between spending enough time caring for the clutch and obtaining enough nutrients at sea. [ABSTRACT FROM AUTHOR]

Following the discoveries of telomeres and of their implications in terms of health and ageing, there has been a growing interest into the study of telomere dynamics in wild vertebrates. Telomeres are repeated sequences of non-coding DNA located at the terminal ends of chromosomes and they play a major role in maintaining chromosome stability. Importantly, telomeres shorten over time and shorter telomeres seem to be related with lower survival in vertebrates. Because of this potential link with longevity, it is crucial to understand not only the ecological determinants of telomere dynamics but also the regulatory endocrine mechanisms that may mediate the effect of the environment on telomeres. In this paper, we review the relationships that link environmental conditions, glucocorticoids (GC, the main hormonal mediator of allostasis) and telomere length in vertebrates. First, we review current knowledge about the determinants of inter-individual variations in telomere length. We emphasize the potential strong impact of environmental stressors and predictable life-history events on telomere dynamics. Despite recent progress, we still lack crucial basic data to fully understand the costs of several life-history stages and biotic and abiotic factors on telomere length. Second, we review the link that exists between GCs, oxidative stress and telomere dynamics in vertebrates. Although circulating GC levels may be closely and functionally linked with telomere dynamics, data are still scarce and somewhat contradictory. Further laboratory and field studies are therefore needed not only to better assess the proximate link between GC levels and telomere dynamics, but also to ultimately understand to what extent GCs and telomere length could be informative to measure the fitness costs of specific life-history stages and environmental conditions. Finally, we highlight the importance of exploring the functional links that may exist between coping styles, the GC stress response, and telomere dynamics in a life-history framework. To conclude, we raise new hypotheses regarding the potential of the GC stress response to drive the trade-off between immediate survival and telomere protection. [ABSTRACT FROM AUTHOR]