Trace element concentrations in feathers and blood of Northern goshawk (Accipiter gentilis) nestlings from Norway and Spain.

Information on trace element pollution in the terrestrial environment and its biota is limited compared to the marine environment. In the present study, we collected body feathers and blood of 37 Northern goshawk (Accipiter gentilis) nestlings from Tromsø (northern Norway), Trondheim (central Norway), and Murcia (southeastern Spain) to study regional exposure, hypothesizing the potential health risks of metals and other trace elements. Blood and body feathers were analyzed by a high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) for aluminum (Al), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg) and lead (Pb). The influence of regional differences, urbanization and agricultural land usage in proximity to the nesting Northern goshawks was investigated using particular spatial analysis techniques. Most trace elements were detected below literature blood toxicity thresholds, except for elevated concentrations (mean ± SD µgml-1 ww) found for Zn (5.4 ± 1.5), Cd (0.00023 ± 0.0002), and Hg (0.021 ± 0.01). Corresponding mean concentrations in feathers (mean ± SD µgg-1 dw) were 82.0 ± 12.4, 0.0018 ± 0.002, and 0.26 ± 0.2 for Zn, Cd and Hg respectively. Multiple linear regressions indicated region was a significant factor influencing Al, Zn, Se and Hg feather concentrations. Blood Cd and Hg concentrations were significantly influenced by agricultural land cover. Urbanization did not have a significant impact on trace element concentrations in either blood or feathers. Overall metal and trace element levels do not indicate a high risk for toxic effects in the nestlings. Levels of Cd in Tromsø and Hg in Trondheim were however above sub-lethal toxic threshold levels. For holistic risk assessment purposes it is important that the concentrations found in the nestlings of this study indicate that terrestrial raptors are exposed to various trace elements.

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.

DNA double-strand breaks in incubating female common eiders (Somateria mollissima): Comparison between a low and a high polluted area.

Alterations in the genetic material may have severe consequences for individuals and populations. Hence, genotoxic effects of environmental exposure to pollutants are of great concern. We assessed the impact of blood concentrations of persistent organic pollutants (POPs) and mercury (Hg) on DNA double-strand break (DSB) frequency, in blood cells of a high-exposed Baltic, and lower exposed Arctic population of common eiders (Somateria mollissima). Furthermore, we examined whether the genotoxic response was influenced by antioxidant concentration (plasma total glutathione (tGSH) and total antioxidant capacity) and female body mass. The DNA DSB frequency did not differ between the two populations. We found significant positive relationships between Hg and DNA DSB frequency in Baltic, but not in Arctic eiders. Although both p,p'-DDE and PCB 118 had a lesser effect than Hg, they exhibited a positive association with DNA DSB frequency in Baltic eiders. Antioxidant levels were not important for the genotoxic effect, suggesting alternative mechanisms other than GSH depletion for the relationship between Hg and DNA DSBs. Hence, the Baltic population, which is considered to be endangered and is under the influence of several environmental stressors, may be more susceptible to genotoxic effects of environmental exposure to Hg than the Arctic population.

DNA double-strand breaks in relation to persistent organic pollutants in a fasting seabird.

Lipophilic persistent organic pollutants (POPs) are released from fat reserves during fasting, causing increased blood concentrations. Thus, POPs represent a potential anthropogenic stressor during fasting periods. We analysed the blood of female common eiders (Somateria mollissima) by using agarose gel electrophoresis and image data analysis to quantify the DNA-fraction, of total DNA, that migrated into the gel (DNA-FTM) as a relative measure of DNA double strand-breaks (DSBs) during the fasting incubation period in the high arctic. In 2008 and in 2009 blood samples were obtained for analysis of 9 POPs and DNA-FTM at day 5 of the incubation period, and then in the same individuals at day 20. This unique study design gave us the opportunity to analyse the same individuals throughout two points in time, with low and high stress burdens. During the incubation period the body mass (BM) decreased by 21-24%, whereas the POP levels increased by 148-639%. The DNA-FTM increased by 61-67% (being proportional to the increase in DSBs). At day 5, but not day 20, DNA-FTM was positively correlated with most analysed POPs. The increase in DNA-FTM was positively correlated with the decrease in BM (g) during incubation. Thus, we suggest that fasting stress (BM loss) decreases DNA integrity and that stress caused by fasting on BM loss appeared to override the additional stress caused by concurrent increase in levels of the analysed POPs in the eiders. Blood levels of POPs in the eiders in Svalbard were relatively low, and additive and/or synergistic genotoxic effects of fasting stress and POP exposure may occur in populations with higher POP levels.

Organohalogen contaminants and Blood plasma clinical-chemical parameters in three colonies of North Atlantic Great skua (Stercorarius skua).

The present study compares blood plasma clinical-chemical parameters (BCCPs) in birds from three geographically distinct North Atlantic Great skua (Stercorarius skua) colonies. Birds from these sites bioaccumulate different POP (persistent organic pollutant) concentrations and that enabled us to compare Great skua BCCPs in different exposure scenarios. Persistent organic pollutants (organochlorines: PCB, DDT, chlordanes, HCB, HCH, mirex and brominated flame retardants: PBDEs) and nineteen BCCPs were analysed in 114 adult Great skuas sampled during summer 2009 in North Atlantic colonies at Bjørnøya (n=42), Iceland (n=57) and Shetland (n=15). Specimens from Bjørnøya had the highest blood plasma concentrations of all contaminant groups followed by Iceland and Shetland birds, respectively (ANOVA: p<0.05). Most of the 19 BCCP parameters followed the pattern of colony differences found for contaminants, with Bjørnøya having the highest concentrations. However seven BCCPs, the three liver enzymes ALKP, ALAT and GGT as well as bile acids, cholesterol, sodium and potassium, did not differ between colonies (ANOVA: p>0.05). Therefore correlation analyses of these seven BCCPs vs. POPs were done on the combined colony data while the analyses of the remaining 12 BCCPs were carried out for each colony separately. The analyses of combined colony data showed that the blood plasma concentration of liver enzymes ALAT and GGT increased with increasing concentrations of ΣPBDE and ΣHCH, HCB and ΣCHL, respectively (all Pearson's p<0.05). In Great skuas from Shetland, the important osmotic transport protein albumin increased with increasing concentrations of ΣPCB and ΣDDT, while total blood plasma protein increased with ΣPCB, ΣDDT, ΣHCH and HCB concentrations (all Pearson's p<0.05). In both Bjørnøya and Iceland skuas, blood plasma pancreatic enzyme amylase decreased with increasing ΣHCH concentrations while the erythrocyte waste product total bilirubin in blood plasma increased with increasing ΣHCH and ΣPBDE concentrations in Iceland Great skuas (all Pearson's p<0.05). In Bjørnøya birds, blood plasma urea from protein metabolism (reflects kidney function) increased with increasing ΣPBDE concentrations (Pearson's p<0.05). Furthermore, a redundancy analysis showed that 10.6% of the variations in BCCPs could be explained by the variations in POP concentrations. Based on these results we suggest that liver and renal functions could be negatively affected by different POP compounds. It is, however, uncertain if the colony BCCP differences and their relationship to POP concentrations reflect health effects that could have an overall impact on the populations via reduced survival and reproduction parameters.

Reproductive recovery of a common eider Somateria mollissima population following reductions in discharges of polycyclic aromatic hydrocarbons (PAHs).

Polycyclic aromatic hydrocarbons (PAHs) are widely distributed toxic compounds in marine ecosystems, but the effects of such pollutants on populations of aquatic birds are poorly known. This study examined the reproductive biology of a marine duck, the common eider (Somateria mollissima), in a Norwegian fjord that received high input of PAHs over several decades. Numbers of breeding females and post-hatch duckling mortality were compared between the years before and after termination of PAH discharges (1989/1990). Moreover, 5 years after the pollution was terminated, reproductive parameters were compared between the polluted fjord and a nearby unpolluted area, to investigate long-term effects. The environmental impact of the pollution peaked in the 1980s, and during this time the number of breeding eiders was halved in the study colony. The duckling mortality was very high, peaking in 1991 when about 8 % of all hatched ducklings were found dead in or near the nest. Since 1993 the ratio of dead ducklings per breeding female stabilized at about one third of the level before the termination of the PAH discharges. Moreover, between 1994 and 1999 the numbers of breeding females increased by 50 %, and in 1995 females in the polluted colony were in better condition, laid larger eggs and had shorter incubation periods than females in the unpolluted area. This study indicates that in the 1980s, PAH pollution affected the reproduction of the eiders in the polluted fjord, although other natural factors may also have influenced eider reproduction. A few years after the pollution level dropped, reproductive output improved strongly, but the number of ducklings dying in the nest was still relatively high compared to unpolluted areas.

Long-term monitoring of exposure to toxic and essential metals and metalloids in the tawny owl (Strix aluco): Temporal trends and influence of spatial patterns.

As a result of regulatory decisions, atmospheric deposition of most toxic metals and metalloids (MEs) has decreased in Europe over the past few decades. However, little is known about how this reduction translates into exposure at higher trophic levels in the terrestrial environment where temporal trends may be spatially heterogeneous due to local current or legacy sources of emissions (e.g., industry) or long-range transport of elements (e.g., marine transport). The aim of this study was to characterize temporal and spatial trends of exposure to MEs in terrestrial food webs using a predatory bird, the tawny owl Strix aluco, as a biomonitor. Toxic (Al, As, Cd, Hg, Pb) and essential/beneficial (B, Co, Cu, Mn, Se) elemental concentrations were measured in feathers of nest-captured females from 1986 to 2016, extending a previous study published over the time-series 1986-2005 (n = 1051), in a breeding population in Norway. A drastic decline over time was shown for the toxic MEs (-97 % for Pb, -89 % for Cd, -48 % for Al, and -43 % for As) except Hg. The beneficial elements B, Mn, and Se showed oscillations but an overall decline (-86 %, -34 %, and -12 %, respectively) whereas the essentials Co and Cu did not exhibit significant trends. The distance to potential sources of contamination influenced both the spatial patterns of concentrations in owl feathers and their temporal trends. The accumulation of As, Cd, Co, Mn and Pb was overall higher in the vicinity of sites recorded as polluted, and a greater temporal decrease of As, B, and Cd concentrations was found in the areas of further distance to polluted sites. The decrease of Pb concentrations was sharper further from the coast during the 1980s than in coastal areas, while the opposite was observed for Mn. The levels of Hg and Se were higher in coastal areas, and Hg temporal trends differed according to the distance to the coast. This study highlights the valuable insights provided by long-term survey of wildlife exposure to pollutants and landscape indicators to reveal regional or local patterns and detect unexpected events, data that are crucial for regulation and conservation of ecosystem health.

Blood plasma clinical-chemical parameters as biomarker endpoints for organohalogen contaminant exposure in Norwegian raptor nestlings.

Raptors are exposed to biomagnifying and toxic organohalogenated compounds (OHCs) such as organochlorines, brominated flame retardants and perfluorinated compounds. To investigate how OHC exposure may affect biochemical pathways we collected blood plasma from Norwegian northern goshawk (n=56), golden eagle (n=12) and white-tailed eagle (n=36) nestlings during three consecutive breeding seasons. We found that blood plasma concentrations of calcium, sodium, creatinine, cholesterol, albumin, total protein, urea, inorganic phosphate, protein:creatinine, urea:creatinine and uric acid:creatinine ratios and liver enzymes ALKP and ALAT were positively correlated to PCBs, chlordanes, p,p'-DDE, HCB, PFCs and/or PBDEs. Total bilirubin and glucose were negatively correlated to PCBs while magnesium and potassium were negatively correlated to HCB and p,p'-DDE. In addition, protein:creatinine and ALAT were also negatively correlated to PCBs and PFCs, respectively. The most significant relationships were found for the highly contaminated northern goshawks and white-tailed eagles. The statistical relationships between OHCs and BCCPs indicate that biochemical pathways could be influenced while it is uncertain if such changes have any health effects. The OHC concentrations were below concentrations causing reproductive toxicity in adults of other raptor species but similar to those of concern for endocrine disruption of thyroid hormones in e.g., bald eagles.

Impacts of climate and feeding conditions on the annual accumulation (1986-2009) of persistent organic pollutants in a terrestrial raptor.

The relationships between climate variability, feeding conditions, and the annual accumulation of polychlorinated biphenyls (PCB), 1,1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE) and polybrominated diphenyl ethers (PBDE) in eggs (n = 168) of tawny owls (Strix aluco) were assessed over a 24-year period (1986-2009) in Central Norway. Winter climate variables included the North Atlantic Oscillation (NAO) and snow conditions, whereas feeding conditions were assessed using vole abundance. The concentrations of all compounds declined between 79% (p,p'-DDE) and 86% (PBDE) over the time period. For PCB and p,p'-DDE, the accumulation was positively associated with snow depth, and negatively associated with NAO (i.e., high accumulation in cold and dry winters) when vole abundance was low, suggesting trade-offs between winter severity and feeding conditions. That is, females mobilize more body fat reserves in cold winters when feeding conditions are poor, which results in increased circulating contaminant concentrations and maternal transfer to the eggs. Owls may also have been forced to feed on prey with higher contaminant loads due to restricted prey availability. For the recently banned PBDEs, the accumulation was high when NAO was low, while snow depth was positively associated with PBDE accumulation only when feeding conditions were good. This suggests somewhat different dynamics of PBDE in the environment or in the owls, compared to PCB and p,p'-DDE. However, climate and feeding conditions explained as much of the annual variation in concentrations of all POPs, as the overall decreasing trend over the 24 years. Hence, such factors should be considered in monitoring programs for POPs. Moreover, to better understand the mechanisms of climate effects on POP accumulation, future studies should measure pollutants in different components of the food chain.

A novel use of the leukocyte coping capacity assay to assess the immunomodulatory effects of organohalogenated contaminants in avian wildlife.

Apex predators are characterized by high levels of biomagnifying organohalogenated contaminants (OHCs) which have been found to induce detrimental health effects in wildlife, such as immune system impairment. The leukocyte coping capacity (LCC) assay is a functional real-time measure of an innate immune response essential in pathogen resistance, known as the respiratory burst. The current study suggests the novel use of this tool to test whether OHCs impair the innate immune system of a sentinel top predator, the white-tailed eagle (Haliaeetus albicilla; WTE). The LCC analysis was performed in the field on WTE nestlings (n = 84) from northern Norway over two breeding seasons. Poly- and perfluoroalkyl substances (PFAS) dominated the total OHC load, surpassing the levels of legacy organochlorines. In addition, we detected significant negative correlations between concentrations of all polychlorinated biphenyls, p,p'-dichlorodiphenyldichloroethylene, perfluorohexane sulfonic acid and long-chain perfluorocarboxylic acids and the LCC of WTE nestlings. Based on our current findings reflecting a potential negative effect of both emerging and legacy OHCs on innate immune capacity, we suggest LCC to be a relevant and accessible test expanding the ecotoxicological toolbox to assess sub-lethal effects of OHCs in apex avian wildlife.

White-tailed eagle (Haliaeetus albicilla) feathers from Norway are suitable for monitoring of legacy, but not emerging contaminants.

While feathers have been successfully validated for monitoring of internal concentrations of heavy metals and legacy persistent organic pollutants (POPs), less is known about their suitability for monitoring of emerging contaminants (ECs). Our study presents a broad investigation of both legacy POPs and ECs in non-destructive matrices from a bird of prey. Plasma and feathers were sampled in 2015 and 2016 from 70 whitetailed eagle (Haliaeetus albicilla) nestlings from two archipelagos in Norway. Preen oil was also sampled in 2016. Samples were analysed for POPs (polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorinated pesticides (OCPs)) and ECs (per- and polyfluoroalkyl substances (PFASs), dechlorane plus (DPs), phosphate and novel brominated flame retardants (PFRs and NBFRs)). A total of nine PCBs, three OCPs, one PBDE and one PFAS were detected in over 50% of the plasma and feather samples within each sampling year and location. Significant and positive correlations were found between plasma, feathers and preen oil concentrations of legacy POPs and confirm the findings of previous research on the usefulness of these matrices for non-destructive monitoring. In contrast, the suitability of feathers for ECs seems to be limited. Detection frequencies (DF) of PFASs were higher in plasma (mean DF: 78%) than in feathers (mean DF: 38%). Only perfluoroundecanoic acid could be quantified in over 50% of both plasma and feather samples, yet their correlation was poor and not significant. The detection frequencies of PFRs, NBFRs and DPs were very low in plasma (mean DF: 1-13%), compared to feathers (mean DF: 10-57%). This may suggest external atmospheric deposition, rapid internal biotransformation or excretion of these compounds. Accordingly, we suggest prioritising plasma for PFASs analyses, while the sources of PFRs, NBFRs and DPs in feathers and plasma need further investigation.

Perfluorinated, brominated, and chlorinated contaminants in a population of lesser black-backed gulls (Larus fuscus).

Protein-bound perfluorinated compounds (PFCs) and lipid-soluble polybrominated diphenyl ethers (PBDEs) and organochlorines (OCs) were measured in whole blood from a large number (n = 83) of breeding lesser black-backed gulls (Larus fuscus) caught during two distinct sampling periods in a colony on the coast of northern Norway. We analyzed 14 PFCs (seven were detected in more than 75% of samples), 10 PBDEs (only BDE 47 was detected), and 27 OCs, including 12 polychlorinated biphenyl (PCB) congeners (14 OCs were detected). Median total PFC concentration was higher than median total OC concentration (43 vs 39 ng/g wet wt). Perfluorooctane sulfonate (PFOS) was the dominant PFC (mean relative contribution of PFOS to total contaminant concentration in blood [Sigmatotal contaminants] was 38%), whereas total PCB (26% of Sigmatotal contaminants) and p,p'-DDE (2,2-bis(4-chlorophenyl)-1,1-dichloroethene; 13% of Sigmatotal contaminants) were the dominant OCs. No covariability was found between protein-bound and lipid-soluble compounds; individuals with high concentrations of PFCs did not have high concentrations of OCs or BDE 47. The concentrations of PFCs were lower in birds caught during the late sampling period compared to those of the early period, and females had lower levels of some PFCs compared with males, suggesting that females sequester fluorinated substances into eggs. For lipid-soluble compounds, no significant sex or sampling period differences were found, except that trans-nonachlor, cis-nonachlor, and p,p'-DDE concentrations were lower in birds caught during the late sampling period. The pattern of PFC compounds (relative to PFOS) and lipid-soluble compounds (relative to PCB 153) differed between sampling periods in females but not in males. Finally, PFCs were distributed more uniformly within the population than the lipid-soluble compounds, for which the distributions were strongly negatively skewed.

Reproductive performance and organochlorine pollutants in an Antarctic marine top predator: the south polar skua.

Despite low levels of organochlorine contaminants (OCs) in Antarctic biota, some compounds may exceed the levels in equivalent Arctic species, and previous studies have found biochemical evidence of pollutant exposure in south polar skuas (Catharacta maccormicki), a common marine top predator in the region. In this study we examined relationships between fitness components (fecundity and adult return rate between breeding seasons) and concentrations of OCs in this species. In 65 nests, both males and females were caught, and using principal component analyses (PCA) we produced composite measurements (PC1 and PC2) of six highly correlated OCs measured in blood samples. Although the concentrations of OC were below those documented to have reproductive effects in other aquatic birds, we found that the eggs of females with high levels of OCs in the blood hatched later, and their chicks were in poorer condition at hatching, than females with low OC levels. Thus OCs may delay reproduction and reduce foetal growth in the skuas. However, there was no relationship between the parents' OC residues and the occurrence of non-viable eggs, although the proportion of nests containing non-viable eggs was high (47%). Moreover, there were no significant relationships between OCs and reproductive variables in males, even if males had higher OC levels than females, and no associations between OCs and adult return rate between breeding seasons.

Blood and feather concentrations of toxic elements in a Baltic and an Arctic seabird population.

We report blood and feather concentrations of elements in the Baltic Sea and Arctic population of common eiders (Somateria mollissima). The endangered Baltic Sea population of eiders was demonstrably affected by element pollution in the 1990s. While blood concentrations of Hg were higher in Baltic breeding eiders, blood Se, As and Cd concentrations were higher in Arctic eiders. Blood concentrations of Pb, Cr, Zn and Cu did not differ between the two populations. While blood Pb concentrations had declined in Baltic eiders since the 1990s, Hg concentrations had not declined, and were above concentrations associated with adverse oxidative effects in other bird species. Inconsistent with blood concentrations, feather concentrations suggested that Pb, Zn, and Cd exposure was higher in Baltic eiders, and that Hg exposure was higher in Arctic eiders. Our study thus emphasizes the need for comprehensive evaluation of toxic element status, covering the annual cycle of a species.

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.

Anti-parasite treatment removes negative effects of environmental pollutants on reproduction in an Arctic seabird.

Recent studies have shown that the detrimental effects of anthropogenic pollutants may be worse if organisms are exposed to natural stress. In this study, we examined whether negative effects of organochlorines (OCs) could be influenced by parasites. In two breeding seasons, we administered an anti-helminthic drug to groups of breeding glaucous gulls (Larus hyperboreus), whereas control groups were placebo treated. In all birds, blood residues of the most important OCs in the study population (hexachlorobenzene, oxychlordane, p,p'-dichlorodiphenyldichloroethylene and polychlorinated biphenyl), were measured. The relationships between OCs and fitness components (i.e. nesting success and return rate between breeding seasons) were then compared between the birds receiving anti-parasite treatment and the controls. Among untreated males, higher blood residues of OCs were associated with lowered nesting success, while in males receiving anti-parasite treatment, there was no detrimental effect of OCs on fitness. Return rate was not affected by treatment or OCs. Our findings suggest that parasites may be an important factor in triggering reproductive effects of such pollutants, and that relatively low levels of OCs may have serious reproductive consequences in natural populations when stress from other sources is high.

Pinpointing potential causative agents in mixtures of persistent organic pollutants in observational field studies: a review of glaucous gull studies.

Since different organochlorine contaminants (OCs) are often highly correlated in biota, a major challenge in observational field studies is to establish whether some OCs are potentially important causative agents of adverse effects. A possible solution to this problem is to compare the strength of the effects of different OCs on a number of outcome parameters, and then examine if some compounds are more consistently reliable predictors of adverse effects. In this analysis the four most common OCs (hexachlorobenzene [HCB], oxychlordane, p,p'-dichlorodiphenyldichloroethylene [DDE], and polychlorinated biphenyls [PCBs]) in arctic glaucous gulls (Larus hyperboreus) were ranked in relation to 19 different outcome parameters, for which at least 1 of the 4 OCs were significantly related. PCBs, made up close to 75% of the measured sigmaOCs, DDE 17-18%, and HCB and oxychlordane 3-4%, respectively. Despite relatively low levels of oxychlordane and HCB, these compounds tended to be more reliable predictors of adverse effects and were ranked highest for 11 and 10 of the 19 outcome parameters, respectively. PCBs and DDE were only ranked highest for seven of the outcome parameters. Oxychlordane, HCB, DDE, and PCB were "not significant" two, six, six, and eight times, respectively. Oxychlordane was significantly more likely to be related to adverse effects than DDE. Even if effects of OCs may depend on a complex interaction between different compounds, this analysis indicates that adverse effects are more likely to occur in glaucous gulls with relatively high concentrations of oxychlordane and HCB.

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.

Variation in concentrations of organochlorines and brominated flame retardants among eggs in abandoned clutches of a terrestrial raptor.

Bird eggs are often used to measure various pollutants in monitoring programs. In protected species, however, it might only be possible to collect eggs abandoned by the parent birds. In order to assess the appropriateness of abandoned eggs for contaminant monitoring we examined intra-clutch variation in concentrations of 24 halogenated organic pollutants (16 organochlorines [OCs] and 8 brominated flame retardants) in six abandoned tawny owl (Strix aluco) clutches from central Norway. The variation among eggs within a clutch was low for nearly all compounds (intra-class correlation >0.9 both for lipid- and wet weight). This study suggests that abandoned eggs provide a relatively reliable measurement of lipophilic pollutants in clutches of terrestrial raptors such as the tawny owl.

Perfluoroalkyl substance concentrations in a terrestrial raptor: relationships to environmental conditions and individual traits.

Accumulation of persistent organic pollutants (POPs) in wildlife may be influenced by the physical and biotic environment, and concentrations vary greatly among areas, seasons, and individuals. Different hypotheses about sources of variation in perfluoroalkyl substance (PFAS) concentrations were examined in eggs (n = 107) of tawny owls (Strix aluco) collected over a 24-yr period (1986-2009) in Norway. Predictor variables included the North Atlantic Oscillation (NAO), temperature, snow, food availability (vole abundance), and individual traits such as age, body condition, and clutch size. Concentrations of both perfluoro-octane sulfonate (PFOS) and perfluoroalkyl carboxylates (PFCAs) varied several fold in the population, both inter- and intra-annually. Moreover, individuals laid eggs with several times higher or lower PFAS concentrations within few years (1 yr-5 yr). After controlling for temporal trends (i.e., declining PFOS and increasing PFCA concentrations), both PFOS and PFCAs were positively associated to the winter NAO in the previous year (NAOy - 1 ), suggesting that atmospheric transport may be affecting the input of PFASs to the local ecosystem. Perfluoro-octane sulfonate was negatively related to temperature, but the pattern was complex as there was an interaction between temperature and the feeding conditions. The PFOS accumulation was highest in years with high vole abundance and low to medium temperatures. For PFCAs, there was an interaction between NAOy - 1 and feeding conditions, suggesting that strong air transport toward Norway and high consumption of voles led to a moderate increase in PFCA accumulation. The individual traits, however, had very little impact on the concentrations of PFASs in the eggs. The present study thus suggests that annual variation in environmental conditions influences the concentrations of PFASs in a terrestrial raptor such as the tawny owl.