Relationships between POPs and baseline corticosterone levels in black-legged kittiwakes (Rissa tridactyla) across their breeding cycle

A retrospective investigation of feather corticosterone in a highly contaminated white-tailed eagle (Haliaeetus albicilla) population

Exposure to persistent organic pollutants (POPs), such as organochlorines (OCs) and polybrominated diphenyl ethers (PBDEs), is associated with adverse health effects in wildlife. Many POPs have been banned and consequently their environmental concentrations have declined. To assess both temporal trends of POPs and their detrimental impacts, raptors are extensively used as biomonitors due to their high food web position and high contaminant levels. White-tailed eagles (WTEs; Haliaeetus albicilla) in the Baltic ecosystem represent a sentinel species of environmental pollution, as they have suffered population declines due to reproductive failure caused by severe exposure to dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCB) during the 1960s through 1980s. However, there is a lack of long-term studies that cover a wide range of environmental contaminants and their effects at the individual level. In this study, we used 135 pooled samples of shed body feathers collected in 1968-2012 from breeding WTE pairs in Sweden. Feathers constitute a temporal archive for substances incorporated into the feather during growth, including corticosterone, which is the primary avian glucocorticoid and a stress-associated hormone. Here, we analysed the WTE feather pools to investigate annual variations in feather corticosterone (fCORT), POPs (OCs and PBDEs), and stable carbon and nitrogen isotopes (SIs; dietary proxies). We examined whether the expected fluctuations in POPs affected fCORT (8-94 pg. mm^-1) in the WTE pairs. Despite clear temporal declining trends in POP concentrations (p < 0.01), we found no significant associations between fCORT and POPs or SIs (p > 0.05 in all cases). Our results do not support fCORT as a relevant biomarker of contaminant-mediated effects in WTEs despite studying a highly contaminated population. However, although not detecting a relationship between fCORT, POP contamination and diet, fCORT represents a non-destructive and retrospective assessment of long-term stress physiology in wild raptors otherwise not readily available.

Occurrence and exposure risk assessment of organochlorine pesticides in two waterbird species from Honghu Lake Wetland, Central China

Monitoring and evaluating bird exposure to hazardous pollutants in wetlands are receiving considerable attention. In this study, the occurrence of 18 organochlorine pesticides (OCPs) in the muscle of bean geese (Anser fabalis) and common teals (Anas crecca) collected from Honghu Lake Wetland (HLW), Central China was studied. Additionally, an exposure risk assessment model was applied to obtain risk levels of OCPs to these birds through three oral routes (food intake, water drinking and soil ingestion). The results suggested that the most abundant OCPs detected in the muscle of waterbirds were DDTs (7.68-602 ng/g lipid weight), followed by HCHs (1.39-89.8 ng/g lipid weight). A significant difference (p < 0.05) existed between two species, but most of OCPs exhibited no statistically relationship with age or gender (p > 0.05). The compositional patterns of OCPs combined with ratios of certain metabolites to their parent compounds indicated that all OCPs in the HLW were largely from historical usage except heptachlor. The exposure risk assessment revealed that common teals with lighter weight had greater exposure risks than bean geese. Of the OCPs analyzed, DDTs could probably cause harm to target birds studied here. Exposure via food intake was identified to be significant while soil ingestion and water drinking contributed least, but they should still be concerned.

New and legacy persistent organic pollutants (POPs) in breeding seabirds from the East Antarctic

Persistent organic pollutants (POPs) are pervasive and a significant threat to the environment worldwide. Yet, reports of POP levels in Antarctic seabirds based on blood are scarce, resulting in significant geographical gaps. Blood concentrations offer a snapshot of contamination within live populations, and have been used widely for Arctic and Northern Hemisphere seabird species but less so in Antarctica. This paper presents levels of legacy POPs (polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)) and novel brominated flame retardants (NBFRs) in the blood of five Antarctic seabird species breeding within Prydz Bay, East Antarctica. Legacy PCBs and OCPs were detected in all species sampled, with Adélie penguins showing comparatively high ∑PCB levels (61.1 ± 87.6 ng/g wet weight (ww)) compared to the four species of flying seabirds except the snow petrel (22.5 ± 15.5 ng/g ww), highlighting that legacy POPs are still present within Antarctic wildlife despite decades-long bans. Both PBDEs and NBFRs were detected in trace levels for all species and hexabromobenzene (HBB) was quantified in cape petrels (0.3 ± 0.2 ng/g ww) and snow petrels (0.2 ± 0.1 ng/g ww), comparable to concentrations found in Arctic seabirds. These results fill a significant data gap within the Antarctic region for POPs studies, representing a crucial step forward assessing the fate and impact of legacy POPs contamination in the Antarctic environment.

Stress responses in captive Crocodylus moreletii associated with metal exposure

Environmental pollution by metals has repercussions on wildlife health. It is known that some metals can have an influence on the neuroendocrine stress response, and at the same time, metals have pro-oxidant effects that can overwhelm the antioxidant system and cause oxidative stress. This study evaluates the association of metals with neuroendocrine stress activity and biomarkers of oxidative stress in 42 captive female Morelet's crocodiles (Crocodylus moreletii). We measured five metals of ecotoxicological importance (Hg, Cd, Pb, Cu and Zn), and three biomarkers of the oxidative stress response in the liver: glutathione (GSH) and glutathione disulfide (GSSG) as markers for antioxidant system and thiobarbituric acid reactive substances (TBARS) for oxidative damage. We also measured one biomarker of the neuroendocrine response to stress: corticosterone (B) in blood plasma. The mean ± SD concentrations of metals in the liver expressed in μg/g (dw) were: Cd: 0.004 ± 0.003, Hg: 0.014 ± 0.019, Cu: 0.017 ± 0.013, Zn: 0.043 ± 0.035, Pb: 0.16 ± 0.256. The mean ± SD of GSH was 0.42 ± 0.35 nmol/mg protein, the mean ± SD of GSSG was 0.24 ± 0.20 nmol/mg protein, the mean ± SD concentrations of TBARS were 0.36 ± 0.21 nmol/mg protein, and the mean ± SD of B was 393.57 ± 405.14 pg/mL. Hg presented a significant negative relationship with corticosterone. Cd had a negative relationship with both GSH and GSSG; meanwhile, Zn showed a negative relationship with TBARS levels, could be a protective element against hepatic oxidative damage. Finally, B had negative relationship with oxidative damage. The connection found between Hg and the neuroendocrine stress response, as well as the correlations of Cd and Zn with oxidative damage and antioxidant activity should be studied further, given their toxicological importance and implications for the conservation of C. moreletii and other crocodilians.

Feathers as an integrated measure of organohalogen contamination, its dietary sources and corticosterone in nestlings of a terrestrial bird of prey, the northern Goshawk (Accipiter gentilis)

In this study, we evaluated the suitability of body feathers, preen oil and plasma for estimation of organohalogen compound (OHC) exposure in northern goshawk Accipiter gentilis nestlings (n = 37; 14 nests). In addition, body feathers received further examination concerning their potential to provide an integrated assessment of (1) OHC exposure, (2) its dietary sources (carbon sources and trophic position) and (3) adrenal gland response (corticosterone). While tetrabromobisphenol A was not detected in any sample, the presence of polychlorinated biphenyls, organochlorine pesticides, polybrominated diphenyl ethers and hexabromocyclododecane in body feathers (median: 23, 19, 1.6 and 3.5 ng g^-1 respectively), plasma (median: 7.5, 6.2, 0.50 and 1.0 ng g^-1 ww, respectively) and preen oil (median: 750, 600, 18 and 9.57 ng g^-1 ww, respectively) suggests analytical suitability for biomonitoring of major OHCs in the three matrices. Furthermore, strong and significant associations (0.20 ≤ R² ≤ 0.98; all P < 0.05) among the OHC concentrations in all three tissues showed that body feathers and preen oil reliably reflect circulating plasma OHC levels. Of the dietary proxies, δ¹³C (carbon source) was the most suitable predictor for variation in feather OHCs concentrations, while no significant relationships between body feather OHCs and δ¹⁵N (trophic position) were found. Finally, body feather corticosterone concentrations were not related to variation in OHC concentrations. This is the first study to evaluate feathers of a terrestrial bird of prey as an integrated non-destructive tool to jointly assess nestling ecophysiology and ecotoxicology.

Telomere length in relation to persistent organic pollutant exposure in white-tailed eagle (Haliaeetus albicilla) nestlings from Sweden sampled in 1995-2013

Telomeres are used as biomarkers of vertebrate health because of the link between their length, lifespan, and survival. Exposure to environmental stressors appears to alter telomere dynamics, but little is known about telomere length and persistent organic pollutant (POP) exposure in wildlife. The white-tailed eagle (WTE; Haliaeetus albicilla) is an avian top predator that accumulates high levels of POPs and may subsequently suffer adverse health effects. Here we study the Baltic WTE population that is well documented to have been exposed to large contaminant burdens, thereby making it a promising candidate species for analyzing pollutant-mediated effects on telomeres. We investigated telomere lengths in WTE nestlings (n = 168) over 19 years and examined legacy POP concentrations (organochlorines and polybrominated diphenyl ethers) in whole blood and serum as potential drivers of differences in telomere length. Although we detected significant year-to-year variations in telomere lengths among the WTE nestlings, telomere lengths did not correlate with any of the investigated POP concentrations of several classes. Given that telomere lengths did not associate with POP contamination in the Baltic WTE nestlings, we propose that other environmental and biological factors, which likely fluctuate on a year-to-year basis, could be more important drivers of telomere lengths in this population.

Contaminants, prolactin and parental care in an Arctic seabird: Contrasted associations of perfluoroalkyl substances and organochlorine compounds with egg-turning behavior

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.

The influence of natural variation and organohalogenated contaminants on physiological parameters in white-tailed eagle (Haliaeetus albicilla) nestlings from Norway

Environmental exposure to organohalogenated contaminants (OHCs), even at low concentrations, may cause detrimental effects on the development and health of wild birds. The present study investigated if environmental exposure to OHCs may influence the variation of multiple physiological parameters in Norwegian white-tailed eagle (Haliaeetus albicilla) nestlings. Plasma and feather samples were obtained from 70 nestlings at two archipelagos in Norway in 2015 and 2016. The selected physiological parameters were plasma concentrations of thyroid hormones (thyroxine, T4 and triiodothyronine, T3), plasma proteins (prealbumin, albumin, α₁-, α₂-, β- and γ-globulins) and selected blood clinical chemical parameters (BCCPs) associated with liver and kidney functioning. Feather concentrations of corticosterone (CORT_f) were also included to investigate the overall stress level of the nestlings. Concentrations of all studied physiological parameters were within the ranges of those found in other species of free-living birds of prey nestlings and indicated that the white-tailed eagle nestlings were in good health. Our statistical models indicated that perfluoroalkyl substances (PFASs) and legacy OHCs, such as polychlorinated biphenyls, organochlorinated pesticides and polybrominated diphenyl ethers, influenced only a minor fraction of the variation of plasma thyroid hormones, prealbumin and CORT_f (5-15%), and partly explained the selected BCCPs (<26%). Most of the variation in each studied physiological parameter was explained by variation between nests, which is most likely due to natural physiological variation of nestlings in these nests. This indicates the importance of accounting for between nest variation in future studies. In the present nestlings, OHC concentrations were relatively low and seem to have played a secondary role compared to natural variation concerning the variation of physiological parameters. However, our study also indicates a potential for OHC-induced effects on thyroid hormones, CORT_f, prealbumin and BCCPs, which could be of concern in birds exposed to higher OHC concentrations than the present white-tailed eagle nestlings.

Can variability in corticosterone levels be related to POPs and OPEs in feathers from nestling cinereous vultures (Aegypius monachus)?

Persistent organic pollutants (POPs) are still globally distributed and some have been shown to interact with the endocrine system of birds. However, the relationship between POPs and the stress response mediated by the hypothalamic-pituitary-adrenal (HPA) axis is still poorly understood. Raising concerns are now focused on the toxic properties of emergent organophosphate ester flame retardants (OPEs), but whether OPEs interact with the HPA axis response has not yet been investigated. We measured corticosterone concentrations in feathers (CORTf) as a long-term biomarker of the bird HPA axis response and we investigated their relationship with POP and OPE concentrations in down feathers of nestling cinereous vultures (Aegypius monachus). We also examined whether high contaminant burden and high CORTf concentrations impacted the duration of chick development. The most predominant compounds were the following: p,p'-DDE (3.28 ± 0.26 ng g^-1 dw) > γ-HCH (0.78 ± 0.09 ng g^-1 dw) > BDE-99 (0.73 ± 0.09 ng g^-1 dw) > CB-153 (0.67 ± 0.04 ng g^-1 dw). The most persistent POP compounds (CB-170, -177, -180, -183, -187, -194 and p,p'-DDE) were associated (P = 0.02) with high concentrations of CORTf (range: 0.55-6.09 pg mm^-1), while no relationship was found when OPEs were tested (P > 0.05). Later egg-laying was positively associated to high levels of CORTf (P = 0.02) and reduced duration of chick development (P < 0.001), suggesting a beneficial effect of the HPA axis response on the growth of the chicks. In addition, males with high concentrations of the most persistent POP compounds tended to show a reduced duration of the nestling period (P = 0.05) and an equal fledging success than chicks with lower levels. These findings suggest that POPs, but not OPEs, may interact with the HPA axis response of chicks, although levels were not high enough to cause detrimental consequences.

Influence of persistent organic pollutants on the endocrine stress response in free-living and captive red kites (Milvus milvus)

Persistent organic pollutants (POPs) have the potential to impair the endocrine regulation of organisms and alter their ability to respond to environmental changes. We studied whether polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) affected the endocrine regulation of free-living and captive red kites (Milvus milvus) through studying the dynamics of corticosterone (CORT) and dehydroepiandrosterone (DHEA). We sampled migratory free-living kites coming from northern Europe and captive kites born in a rehabilitation center in Spain. We used body feathers from the interscapular region as a minimally-invasive and integrative matrix. The most abundant compound detected in free-living kites was 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE; 6.10 ± 1.56 ng g^-1 dw feather) followed by CB-153 (3.10 ± 0.63 ng g^-1 dw feather) and CB-180 (2.43 ± 1.08 ng g^-1 dw feather). In captive kites, the most abundant compounds were 4,4'-dichlorodyphenyltrichloroethane (4,4'-DDT; 2.38 ± 1.30 ng g^-1 dw feather), CB-153 (2.15 ± 0.47 ng g^-1 dw feather) and hexachlorobenzene (HCB; 2.03 ± 0.45 ng g^-1 dw feather) at similar concentrations. Free-living kites showed higher levels of 4,4'-DDE and CB-180 in comparison to captive kites. Age influenced HCB and CB-101 levels, whereas body mass was inversely related to CB-180 and 4,4'-DDT. Interestingly, captive kites showed a ratio DDT/DDE higher than 1 suggesting a relatively recent exposure of DDT, in contrast to free-living kites. Regarding hormonal levels, free-living kites showed higher levels of CORT (3.30 ± 0.22 pg mm^-1 feather) than captive (2.40 ± 0.16 pg mm^-1 feather), reflecting higher allostatic load. In addition, a positive association between PCBs and DDTs and adrenal hormones was found in free-living kites, suggesting an increase of CORT as a response of the endocrine system to cope with stressors and a subsequent elevation of DHEA to ameliorate the potential negative effects that high CORT levels could cause to the organism.

The association between reproductive success with persistent organochlorine pollutants residue in feathers of spur-winged lapwing (Vanellus spinosus L.)

The reproductive and breeding success of wader species is negatively affected by various anthropogenic factors, including persistent organochlorine pollutants (POPs). We aimed to study the association of POPs in feathers with the reproductive success of the spur-winged lapwing (Vanellus spinosus). For this purpose, data on reproductive parameters and feather samples were collected from a breeding population consisting of 19 pairs near Boğazkent district in Antalya, Turkey. Mean concentrations of total polychlorinated biphenyls (ΣPCBs) and organochlorine pesticides (ΣOCPs) were found to be 54 ± 16 ng/g and 520 ng/g in all samples, respectively. In particular, PCB 151 and β-hexachlorocyclohexane had a negative association the various reproductive parameters in the species under consideration. Fledgling success (n = 25) was calculated to be 37.4%, which was negatively associated with the ΣOCP concentrations (r = - 0.99, p = 0.01). According to the results, POP residues are one of the associated factors on the reproductive success of spur-winged lapwing along, with agricultural activity and predation. It is indicated that the species needs a protection plan for prevention declining reproductive success and population size species in Turkey. Besides, our results suggest that bird feathers are a non-destructive bio-monitoring tools to estimate of contamination levels of organic pollutants in a population.

Persistent organic pollutants and organophosphate esters in feathers and blood plasma of adult kittiwakes (Rissa tridactyla) from Svalbard - associations with body condition and thyroid hormones

Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs) and organophosphate esters (OPEs) were assessed in blood plasma and feathers of 19 adult black-legged kittiwakes (Rissa tridactyla) breeding in two colonies (Blomstrandhalvøya and Krykkjefjellet) at the Arctic archipelago, Svalbard. Potential associations with body condition index (BCI) and thyroid hormones were investigated. All compound classes were detected in both blood plasma and feathers, but due to low sample size and volumes, OPEs could only be quantified in four individuals, warranting larger follow-up studies. Kittiwakes breeding at Blomstrandhalvøya had significantly higher concentrations of organic pollutants in blood plasma than kittiwakes breeding at Krykkjefjellet (p < 0.001). Concentrations in blood plasma and feathers did not significantly correlate for any of the investigated compounds, and feather concentrations did not differ significantly between the colonies. This suggests that pollutant levels in adult kittiwake feathers do not reflect local contamination at breeding sites and are as such not useful to monitor local contamination at Svalbard. Significant negative associations between BCI and most pollutants were found in both populations, whereas significant correlations between the BCI, the ratio of total triiodothyronine to free triiodothyronine (TT3:fT3), and several pollutants were only found for kittiwakes from Blomstrandhalvøya (all r ≥ -0.60 and p ≤ 0.05). This indicates that higher levels of circulating pollutants during the breeding period covary with the TT3: fT3 ratio, and may act as an additional stressor during this period.

Do glucocorticoids mediate the link between environmental conditions and telomere dynamics in wild vertebrates? A review

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.

Individual variation of persistent organic pollutants in relation to stable isotope ratios, sex, reproductive phase and oxidative status in Scopoli's shearwaters (Calonectris diomedea) from the Southern Mediterranean

Little is known about the accumulation of persistent organic pollutants (POPs) and its consequences for seabirds in the Mediterranean basin. We characterised the plasma contaminant profile (polychlorinated biphenyls ΣPCBs; organochlorine pesticides ΣOCPs; polybrominated diphenyl ethers ΣPBDEs) of a population of the seabird Scopoli's shearwater (Calonectris diomedea) that breeds in the southern Mediterranean (Linosa Island) and investigated (i) whether sex, stable isotope ratios (related to diet), reproductive phase (early incubation vs. late breeding season) and body mass explained variation in contaminant burden and (ii) whether they predict health-related variables. The predominant category of POPs was ΣPCBs contributing between 53.0 and 92.4% of the total POPs in each shearwater. The percentage contribution of ΣOCPs to total POPs ranged between 7.6 and 47.0%, while that of ΣPBDEs ranged between <1% and 22.1%. Near the end of the breeding season, concentrations of ΣPCBs, ΣOCPs and ΣPOPs were significantly higher than at the beginning of the incubation period. ΣPBDEs were higher in males than females near the end of the breeding season, while they were higher in females than males at the beginning of the egg incubation period. Carbon- and nitrogen isotope ratios and individual body mass were not significantly associated with any contaminant class. Mates differed in the concentration of POPs, but they had similar stable isotope values. There was little evidence for a connection between contaminants and blood-based markers of oxidative balance. None of the contaminants predicted the probability of a bird being resighted as a breeder the following year. Thus, although POPs were present at high concentrations in some individuals, our study suggests little concern regarding POP exposure for this shearwater population.

Temporal variation in circulating concentrations of organochlorine pollutants in a pelagic seabird breeding in the high Arctic

The present study explored short-term temporal variations in circulating concentrations of 3 legacy organochlorines with different physicochemical properties (polychlorinated biphenyl 153 [PCB-153], p,p'-dichlorodiphenyldichloroethylene [DDE], and hexachlorobenzene [HCB]) in breeding kittiwakes (Rissa tridactyla) in a colony in Svalbard (78°N), Norwegian Arctic. Concentrations were measured in blood of a large number (n = 412-521 blood samples, depending on the data analyses) of prebreeding, incubating, and chick-rearing birds over a period of 5 yr (2007-2011). The PCB-153 concentrations were equal in male and female blood in the prebreeding period, whereas females had significantly lower concentrations during incubation and chick rearing, probably because of their ability to eliminate organochlorines through egg laying. A similar temporal pattern was observed with DDE, although the lower concentrations in incubating females were not significant. Males and females had similar concentrations of HCB over all reproductive stages. The concentrations of all 3 compounds varied greatly between years. The concentrations of PCB-153 tended to decline over the study period, whereas concentrations of HCB showed an increasing trend, especially among chick-rearing males late in the season. Concentrations of PCB-153 increased approximately 2.5 times from the prebreeding to the chick-rearing period, concurrent with mobilization of body lipids (reduced body mass). A similar, but less pronounced trend was found for HCB. For DDE, however, kittiwakes had the highest concentrations in the prebreeding period, suggesting relatively high exposure in their winter areas. The present study documented large variations in circulating concentrations of legacy organochlorines among and within breeding seasons in kittiwakes, but the alterations within seasons were relatively consistent from year to year. Environ Toxicol Chem 2017;36:442-448. © 2016 SETAC.

Persistent organic pollutant levels and the importance of source proximity in Baltic and Svalbard breeding common eiders

The distance to sources and the long-range transport potential of persistent organic pollutants (POPs) are important in understanding the impact of anthropogenic pollution on natural seabird populations. The present study documented blood concentrations of POPs in the Baltic Sea (Tvärminne, Finland) population of common eiders (Somateria mollissima) in 2009 and in 2011 and compared the concentrations with the presumably less exposed Arctic population in Svalbard (Kongsfjorden, Norway). The Baltic population had 26, 10, and 5 times greater concentrations of hexachlorocyclohexane, polychlorinated biphenyls, and p,p'-dichlorodiphenyldichloroethylene than the Svalbard population. Unexpectedly, concentrations of chlordanes were higher in Svalbard eiders, whereas concentrations of hexachlorobenzenes (HCBs) did not differ between the 2 populations. Although the similar HCB levels may partly be explained by the high transport potential of HCBs, unknown factors may have been more important than distance to sources and long-range transport potential for the chlordanes. One plausible explanation may be that the fasting-related redistribution of POPs from fat to blood was greater throughout the incubation in Arctic eiders, causing them to have higher blood levels of these POPs at the end of incubation. The blood concentrations of POPs in Baltic eiders were higher than documented in any other eider population and were comparable to levels in seabirds feeding at higher trophic positions in the food chain. Environ Toxicol Chem 2016;35:1526-1533. © 2015 SETAC.

Antioxidant Responses in Relation to Persistent Organic Pollutants and Metals in a Low- and a High-Exposure Population of Seabirds

Oxidative stress occurs when there is an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense. Exposure to pollutants may increase ROS and affect antioxidant levels, and the resulting oxidative stress may negatively affect both reproduction and survival. We measured concentrations of 18 persistent organic pollutants (POPs) and 9 toxic elements in blood, as well as total antioxidant capacity (TAC), total glutathione (tGSH), and carotenoids in plasma of Baltic and Arctic female common eiders (Somateria mollissima) (N = 54) at the end of their incubation-related fasting. The more polluted Baltic population had higher TAC and tGSH concentrations compared to the Arctic population. Carotenoid levels did not differ between populations. The effect of mixtures of pollutants on the antioxidants was assessed, and the summed molar blood concentrations of 14 POPs were positively related to TAC. There was no significant relationship between the analyzed pollutants and tGSH concentrations. The adaptive improvement of the antioxidant defense system in the Baltic population may be a consequence of increased oxidative stress. However, both increased oxidative stress and energy allocation toward antioxidant defense may have adverse consequences for Baltic eiders at the incubation stage, when energy resources reach an annual minimum due to incubation-related fasting.

Increased adrenal responsiveness and delayed hatching date in relation to polychlorinated biphenyl exposure in Arctic-breeding black-legged kittiwakes (Rissa tridactyla)

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.

Survival rate and breeding outputs in a high Arctic seabird exposed to legacy persistent organic pollutants and mercury

Chronic exposure to pollutants may represent a threat for wildlife. We tested whether adult survival rate, breeding probability and breeding success the year of sampling and the following year were affected by blood levels of mercury or persistent organic pollutants in Svalbard black-legged kittiwake Rissa tridactyla, by using capture-mark-recapture models over a five-year period. Survival rate was negatively linked to HCB levels in females, to chlordane mixture and oxychlordane, tended to decrease with increasing PCBs or DDE levels, but was unrelated to mercury. Breeding probability decreased with increasing mercury levels during the sampling year and with increasing CHL or HCB levels during the following year, especially in males observed as breeders. Surprisingly, the probability of raising two chicks increased with increasing HCB levels. Although levels of these legacy pollutants are expected to decline, they represent a potential threat for adult survival rate and breeding probability, possibly affecting kittiwake population dynamics.

Feather corticosterone content in predatory birds in relation to body condition and hepatic metal concentration

This study investigated the feasibility of measuring corticosterone in feathers from cryo-archived raptor specimens, in order to provide a retrospective assessment of the activity of the stress axis in relation to contaminant burden. Feather samples were taken from sparrowhawk Accipiter nisus, kestrel Falco tinnunculus, buzzard Buteo buteo, barn owl Tyto alba, and tawny owl Strix aluco and the variation in feather CORT concentrations with respect to species, age, sex, feather position, and body condition was assessed. In sparrowhawks only, variation in feather CORT content was compared with hepatic metal concentrations. For individuals, CORT concentration (pgmm(-1)) in adjacent primary flight feathers (P5 and P6), and left and right wing primaries (P5), was statistically indistinguishable. The lowest concentrations of CORT were found in sparrowhawk feathers and CORT concentrations did not vary systematically with age or sex for any species. Significant relationships between feather CORT content and condition were observed in only tawny owl and kestrel. In sparrowhawks, feather CORT concentration was found to be positively related to the hepatic concentrations of five metals (Cd, Mn, Co, Cu, Mo) and the metalloid As. There was also a negative relationship between measures of condition and total hepatic metal concentration in males. The results suggest that some factors affecting CORT uptake by feathers remain to be resolved but feather CORT content from archived specimens has the potential to provide a simple effects biomarker for exposure to environmental contaminants.

Polychlorinated biphenyl exposure and corticosterone levels in seven polar seabird species

The role of polychlorinated biphenyls (PCBs) on exposure-related endocrine effects has been poorly investigated in wild birds. This is the case for stress hormones including corticosterone (CORT). Some studies have suggested that environmental exposure to PCBs and altered CORT secretion might be associated. Here we investigated the relationships between blood PCB concentrations and circulating CORT levels in seven free-ranging polar seabird species occupying different trophic positions, and hence covering a wide range of PCB exposure. Blood ∑₇PCB concentrations (range: 61-115,632 ng/g lw) were positively associated to baseline or stress-induced CORT levels in three species and negatively associated to stress-induced CORT levels in one species. Global analysis suggests that in males, baseline CORT levels generally increase with increasing blood ∑₇PCB concentrations, whereas stress-induced CORT levels decrease when reaching high blood ∑₇PCB concentrations. This study suggests that the nature of the PCB-CORT relationships may depend on the level of PCB exposure.

Corticosterone, prolactin and egg neglect behavior in relation to mercury and legacy POPs in a long-lived Antarctic bird

Seabirds often have high loads of contaminants. These contaminants have endocrine disrupting properties but their relationships with some endocrine mechanisms are still poorly investigated in free-living organisms. This is the case for the stress response which shifts energy investment away from reproduction and redirects it towards survival. In birds, this stress response is achieved through a release of corticosterone and is also accompanied by a decrease in circulating prolactin, an anterior pituitary hormone widely involved in regulating parental cares. We measured blood concentrations of some legacy persistent organic pollutants (POPs) and mercury (Hg) and examined their relationships with the corticosterone and prolactin responses of known-age (9-46 years old) incubating snow petrels (Pagodroma nivea) to a standardized capture/handling stress protocol. In this Antarctic seabird, we also investigated whether high contaminant burden correlates with a higher occurrence of egg neglect, a frequently observed behavior in snow petrels. POPs and Hg were unrelated to age. Stress-induced corticosterone concentrations were positively related to POPs in both sexes, and stress-induced prolactin concentrations were negatively related to Hg in males. Egg-neglect behavior was not related to POPs burden, but males with higher Hg concentrations were more likely to neglect their egg. This suggests that in birds, relationships between age and contaminants are complex and that even low to moderate concentrations of POPs and Hg are significantly related to hormonal secretion. In this Antarctic species, exposure to legacy POPs and Hg could make individuals more susceptible to environmental stressors such as ongoing disturbances in Polar Regions.

Endocrine and fitness correlates of long-chain perfluorinated carboxylates exposure in Arctic breeding black-legged kittiwakes

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.

The stress of being contaminated? Adrenocortical function and reproduction in relation to persistent organic pollutants in female black legged kittiwakes

High levels of environmental pollutants such as persistent organic pollutants (POPs) including PCB and DDT have been found in the Arctic and many of those pollutants may impair reproduction through endocrine disruption. Nevertheless, their effects on stress hormones remain poorly understood, especially in free-ranging birds. Corticosterone, the principal glucocorticoid in birds, can indirectly impair reproduction. The aim of the present study was to examine the relationships between POPs and reproduction through their potential consequences on different reproductive traits (breeding decision, egg-laying date, breeding success) and corticosterone secretion (baseline and stress-induced levels). We addressed those questions in an Arctic population of female black-legged kittiwakes during the pre-breeding stage and measured several legacy POPs (PCBs and pesticides: HCB, p,p'-DDE, CHL) in whole blood. POP levels were not related to breeding decision neither to breeding success, whereas females with high levels of pesticides laid their eggs earlier in the season. We found a negative relationship between POP levels and body condition index in non-breeding females. Black-legged kittiwakes with higher levels of PCB showed stronger adrenocortical response when subjected to a capture-handling stress protocol. We suggest that PCBs may disrupt corticosterone secretion whereas the positive relationship between pesticides and egg-laying date could either originate from a direct effect of pesticides or may be related to other confounding factors such as age or individual's quality. Although no direct negative reproduction output of POPs was found in this study, it is possible that the most contaminated individuals would be more sensitive to environmental stress and would be less able to maintain parental investment than less polluted individuals.

Integument colouration in relation to persistent organic pollutants and body condition in arctic breeding black-legged kittiwakes (Rissa tridactyla)

Vertebrates cannot synthetize carotenoids de novo but have to acquire them through their diet. In birds, carotenoids are responsible for the yellow to red colouration of many secondary sexual traits. They are also involved in physiological functions such as immunostimulation and immunoregulation. Consequently, carotenoid-based colouration is very often considered as a reliable signal for health and foraging abilities. Although a few studies have suggested that carotenoid-based coloured traits could be sensitive to environmental pollution such as persistent organic pollutants (POPs) contamination, the relationships between pollutants and colouration remain unclear. Here, we examined the relationships between the colouration of carotenoid-based integuments and individual POP levels in pre-laying female black-legged kittiwakes from very high latitudes. In this area, these arctic seabirds are exposed to high POPs contamination. Additionally, we investigated the relationships between colouration and body condition, a frequently used index of individual quality. We found a negative relationship between POP levels and several components of integument colouration: saturation of eye-ring, gapes and tongue, suggesting that POPs could disrupt colouration of labile integuments in female kittiwakes. In addition, we found that females in better body condition displayed more orange and brighter gapes and tongue than females in poor body condition. These results demonstrate that hue and brightness are sensitive to the current health and nutritional status of female kittiwakes. Overall, our study shows that carotenoid-based colour integuments can be affected by several environmental-driven variables.

Relationships between persistent organic pollutants and circulating immunoglobulin-Y in black-legged kittiwakes and Atlantic puffins

Have Although persistent organic pollutants (POPs) may affect the immune system, few field studies actually examined this effect. There are indications that POP exert effects on the immune system; however, in the Arctic ecosystem data are scarce. The aim of this study was to examine immune functions in two medium trophic-positioned seabirds, the black-legged kittiwakes (Rissa tridactyla) and Atlantic puffins (Fratercula arctica). Overall POP concentrations were higher in kittiwakes than puffins and males had significantly higher concentrations than females. Mean concentrations of total polychlorinated biphenyls (ΣPCB9) were 4700 ± 200 and 9600 ± 1400 ng/g lipid weight and 2800 ± 180 and 3900 ± 200 ng/g lipid weight in female and male kittiwake and puffin blood, respectively. Levels of immunoglobulin-Y (IgY) in blood of kittiwakes were not markedly affected by concentrations of POP. Similarly, the primary IgY response to tetanus toxoid was not affected by POP concentrations in a subsample of immunized kittiwakes. In puffins, there were significant correlations between the IgY-response and some of the POPs, but with low explanatory values. These results suggest that POPs concentrations were lower than, or just at the threshold level for effects of the proposed IgY biomarker. It is also conceivable that the IgY levels are not a suitable endpoint for evaluating perturbation of the immune system in free-living seabirds.