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Fourteen legacy organochlorine (OC) contaminants and 12 perfluoroalkyl substances (PFASs) were measured in eggs of tawny owls (Strix alueco) in central Norway (1986-2019). We expected OCs to have reached stable equilibrium levels due to bans, and that recent phase-out of some PFASs would have slowed the increase of these compounds. ∑OC comprised on average approximately 92% of the measured compounds, whereas ∑PFAS accounted for approximately 8%. However, whereas the ∑OC to ∑PFAS ratio was approximately 60 in the first 5 years of the study, it was only approximately 11 in the last 5 years. Both OC pesticides and polychlorinated biphenyls (PCBs) showed substantial declines over the study period (~85%-98%): hexachlorocyclohexanes and chlordanes seemed to be levelling off, whereas p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and hexachlororbenzene (HCB), and most PCB congeners still seemed to decline at a more or less constant rate. While the concentration of perfluorooctane sulfonic acid (PFOS), the dominating PFAS, was reduced by approximately 43%, other perfluorinated sulfonates (PFSAs) showed only minor changes. Moreover, the median concentrations of seven perfluorinated carboxylic acids (PFCAs) increased approximately five-fold over the study period. Perfluorononanoic acid and perfluoroundecanoate acid, however, seemed to be levelling off in recent years. In contrast, perfluorododecanoic acid, perfluorodecanoate acid, perfluorotridecanoic acid, and perfluorotetradecanoic acid seemed to increase more or less linearily. Finally, perfluorooctanoic acid (PFOA) was increasingly likely to be detected over the study period. Hence, most legacy OCs and PFOS have not reached a lower threshold with stable background levels, and voluntary elimination of perfluoroalkyl carboxylates still has not resulted in declining levels in tawny owls in central Norway. Environ Toxicol Chem 2022;41:1508-1519. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering “all relevant factors.” This ambiguity in the inclusion or exclusion of specific factors (e.g., individual and species-specific biology, diet, or proportion time in treated or contaminated area) can significantly influence the overall risk characterization. In this review, we identify four discrete categories of complexity that should be considered in an exposure assessment—chemical, environmental, organismal, and ecological. These may require more data, but a degree of inclusion at all stages of the risk assessment is critical to moving beyond screening-level methods that have a high degree of uncertainty and suffer from conservatism and a lack of realism. We demonstrate that there are many existing and emerging scientific tools and cross-cutting solutions for tackling exposure complexity. To foster greater application of these methods in wildlife exposure assessments, we present a new framework for risk assessors to construct an “exposure matrix.” Using three case studies, we illustrate how the matrix can better inform, integrate, and more transparently communicate the important elements of complexity and realism in exposure assessments for wildlife. Modernizing wildlife exposure assessments is long overdue and will require improved collaboration, data sharing, application of standardized exposure scenarios, better communication of assumptions and uncertainty, and postregulatory tracking. Integr Environ Assess Manag 2023;00:1–25.

Divergence in the face of high dispersal capabilities is a documented but poorly understood phenomenon. The white-tailed eagle (Haliaeetus albicilla) has a large geographic dispersal capability and should theoretically be able to maintain genetic homogeneity across its dispersal range. However, following analysis of the genomic variation of white-tailed eagles, from both historical and contemporary samples, clear signatures of ancient biogeographic substructure across Europe and the North-East Atlantic is observed. The greatest genomic differentiation was observed between island (Greenland and Iceland) and mainland (Denmark, Norway and Estonia) populations. The two island populations share a common ancestry from a single mainland population, distinct from the other sampled mainland populations, and despite the potential for high connectivity between Iceland and Greenland they are well separated from each other and are characterized by inbreeding and little variation. Temporal differences also highlight a pattern of regional populations persisting despite the potential for admixture. All sampled populations generally showed a decline in effective population size over time, which may have been shaped by four historical events: I) isolation of refugia during the last glacial period 110-115,000 years ago, II) population divergence following the colonization of the deglaciated areas ~10,000 years ago, III) human population expansion, which led to the settlement in Iceland ~1,100 years ago, and IV) human persecution and exposure to toxic pollutants during the last two centuries.

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 conse quently 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 sig nificant 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 popu lation. 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 other wise not readily available.

We investigated trophic dynamics of Hg in the polluted Baltic Archipelago Sea using established trophic magnification (TMFs) and biomagnification factors (BMFs) on a comprehensive set of bird, fish, and invertebrate species. As different ecological and ecophysiological species traits may affect trophic dynamics, we explored the effect of food chain (benthic, pelagic, benthopelagic) and thermoregulatory strategy on trophic total Hg (THg) dynamics, using different approaches to accommodate benthopelagic species and normalize for trophic position (TP). We observed TMFs and most BMFs greater than 1, indicating overall THg biomagnification. We found significantly higher pelagic TMFs (3.58-4.02) compared to benthic ones (2.11-2.34) when the homeotherm bird species were excluded from models, but not when included. This difference between the benthic and pelagic TMFs remained regardless of how the TP of benthopelagic species was modeled, or whether TMFs were normalized for TP or not. TP-corrected BMFs showed a larger range (0.44-508) compared to BMFs representing predator-prey concentration ratios (0.05-82.2). Overall, the present study shows the importance of including and evaluating the effect of ecological and ecophysiological traits when investigating trophic contaminant dynamics.

Climate change may affect temporal trends of persistent organic pollutants (POPs) in Arctic wildlife. We studied how biological and climate variables influence temporal trends of selected POP groups in landlocked Arctic char muscle and in ringed seal blubber from West and East Greenland. The variables included fish length or animal age, sex, a stable nitrogen isotope, sea ice extent, air or seawater temperature, salinity and the Arctic Oscillation Index (AOI). Model selection for multiple regression showed that the most important predictors varied among POP groups, species and region. Decreasing time trends were found for all POP groups with the exception of hexachlorobenzene (HCB) concentration which remained stable in Arctic char and ringed seals from West Greenland. When retained in the most parsimonious model, the AOI was positively associated with POP concentrations for East Greenland seals, but negatively for West Greenland seals. Seawater temperature and sea ice extent were positively associated with POP concentrations. The effects of explanatory variables on the annual rates of change in POP concentrations were relatively minor relative to the decline caused by reduction in POP emissions following national and international regulations introduced since the 1970s.

The Green Edge project was designed to investigate the onset, life and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in arctic ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the arctic environment will affect it. Green Edge was a large multidisciplinary collaborative project bringing researchers and technicians from 28 different institutions in seven countries, together aiming at understanding these changes and their impacts into the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice-camp and a research vessel in the Baffin Bay, canadian arctic. This paper describes the sampling strategy and the data set obtained from the research cruise, which took place aboard the Canadian Coast Guard Ship (CCGS) Amundsen in spring 2016. The dataset is available at https://doi.org/10.17882/59892 (Massicotte et al., 2019a).

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.

Movalli, Paola et al., The chemical industry is the leading sector in the EU in terms of added value. However, contaminants pose a major threat and significant costs to the environment and human health. While EU legislation and international conventions aim to reduce this threat, regulators struggle to assess and manage chemical risks, given the vast number of substances involved and the lack of data on exposure and hazards. The European Green Deal sets a ‘zero pollution ambition for a toxic free environment’ by 2050 and the EU Chemicals Strategy calls for increased monitoring of chemicals in the environment. Monitoring of contaminants in biota can, inter alia: provide regulators with early warning of bioaccumulation problems with chemicals of emerging concern; trigger risk assessment of persistent, bioaccumulative and toxic substances; enable risk assessment of chemical mixtures in biota; enable risk assessment of mixtures; and enable assessment of the effectiveness of risk management measures and of chemicals regulations overall. A number of these purposes are to be addressed under the recently launched European Partnership for Risk Assessment of Chemicals (PARC). Apex predators are of particular value to biomonitoring. Securing sufficient data at European scale implies large-scale, long-term monitoring and a steady supply of large numbers of fresh apex predator tissue samples from across Europe. Natural science collections are very well-placed to supply these. Pan-European monitoring requires effective coordination among field organisations, collections and analytical laboratories for the flow of required specimens, processing and storage of specimens and tissue samples, contaminant analyses delivering pan-European data sets, and provision of specimen and population contextual data. Collections are well-placed to coordinate this. The COST Action European Raptor Biomonitoring Facility provides a well-developed model showing how this can work, integrating a European Raptor Biomonitoring Scheme, Specimen Bank and Sampling Programme. Simultaneously, the EU-funded LIFE APEX has demonstrated a range of regulatory applications using cutting-edge analytical techniques. PARC plans to make best use of such sampling and biomonitoring programmes. Collections are poised to play a critical role in supporting PARC objectives and thereby contribute to delivery of the EU’s zero-pollution ambition., This paper was carried out in collaboration between ‘European Raptor Biomonitoring Facility’ (COST Action 16224), and the project ‘LIFE APEX—Systematic use of contaminant data from apex predators and their prey in chemicals management’ (LIFE17 ENV/SK/000355). European Raptor Biomonitoring Facility is supported by COST (European Cooperation in Science and Technology) and funded by the Horizon 2020 Framework Programme of the European Union. LIFE APEX is funded by the LIFE Programme, the EU’s funding instrument for the environment and climate action.

There has been a considerable number of reports on Hg concentrations in Arctic mammals since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of the exposure to mercury (Hg) in Arctic biota in 2010 and 2018. Here, we provide an update on the state of the knowledge of health risk associated with Hg concentrations in Arctic marine and terrestrial mammal species. Using available population-specific data post-2000, our ultimate goal is to provide an updated evidence-based estimate of the risk for adverse health effects from Hg exposure in Arctic mammal species at the individual and population level. Tissue residues of Hg in 13 species across the Arctic were classified into five risk categories (from No risk to Severe risk) based on critical tissue concentrations derived from experimental studies on harp seals and mink. Exposure to Hg lead to low or no risk for health effects in most populations of marine and terrestrial mammals, however, subpopulations of polar bears, pilot whales, narwhals, beluga and hooded seals are highly exposed in geographic hotspots raising concern for Hg-induced toxicological effects. About 6% of a total of 3500 individuals, across different marine mammal species, age groups and regions, are at high or severe risk of health effects from Hg exposure. The corresponding figure for the 12 terrestrial species, regions and age groups was as low as 0.3% of a total of 731 individuals analyzed for their Hg loads. Temporal analyses indicated that the proportion of polar bears at low or moderate risk has increased in East/West Greenland and Western Hudson Bay, respectively. However, there remain numerous knowledge gaps to improve risk assessments of Hg exposure in Arctic mammalian species, including the establishment of improved concentration thresholds and upscaling to the assessment of population-level effects.

To assess how climate-sensitive factors may affect the exposure to organochlorines (OCs) and perfluoroalkyl substances (PFASs), we monitored concentrations in eggs of the common goldeneye (Bucephala clangula) over two decades (1999–2019) in central Norway. The goldeneye alternates between marine and freshwater habitats and is sensitive to climate variation, especially due to alterations in ice conditions which may affect feeding conditions. We assessed how biological factors such as diet (stable isotopes δ13C and δ15N), the onset of egg laying, and physical characteristics such as winter climate (North Atlantic Oscillation: NAOw) influenced exposure. We predicted compounds to show different temporal trends depending on whether they were still in production (i.e. some PFASs) or have been banned (i.e. legacy OCs and some PFASs). Therefore, we controlled for potential temporal trends in all analyses. There were declining trends for α- and γ-hexachlorocyclohexane (HCH), oxychlordane, cis-chlordane, cis-nonachlor, p,p′-dichlorodiphenyltrichloroethane (p.p′-DDT) and less persistent polychlorinated biphenyl (PCB) congeners (e.g. PCB101). In contrast, the dominant compounds, such as p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) and persistent PCB congeners, were stable, whereas hexachlorobenzene (HCB) increased over time. Most OCs were positively related to δ15N, suggesting higher exposure in birds feeding at upper trophic levels. Chlordanes and HCB were positively associated with δ13C, indicating traces of marine input for these compounds, whereas the relationships to most PCBs were negative. Among PFASs, perfluorooctanesulfonamide (PFOSA) and perfluorohexane sulfonic acid (PFHxS) declined. Most PFASs were positively associated with δ13C, whereas there were no associations with δ15N. Egg laying date was positively associated to perfluoroheptanesulfonic acid (PFHpS), perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), suggesting that some of the PFAS load originated from the wintering locations. Although NAOw had little impact on the exposure to organohalogenated contaminants, factors sensitive to climate change, especially diet, were associated with the exposure to OHCs in goldeneyes.

We examined spatial variation in total mercury (THg) concentrations in 100 hair samples collected between 2008 and 2016 from 87 polar bears (Ursus maritimus) from the Norwegian (Svalbard Archipelago, western Barents Sea) and Russian Arctic (Kara Sea, Laptev Sea, and Chukchi Sea). We used latitude and longitude of home range centroid for the Norwegian bears and capture position for the Russian bears to account for the locality. We additionally examined hair stable isotope values of carbon (δ13C) and nitrogen (δ15N) to investigate feeding habits and their possible effect on THg concentrations. Median THg levels in polar bears from the Norwegian Arctic (1.99 μg g−1 dry weight) and the three Russian Arctic regions (1.33–1.75 μg g−1 dry weight) constituted about 25–50% of levels typically reported for the Greenlandic or North American populations. Total Hg concentrations in the Norwegian bears increased with intake of marine and higher trophic prey, while δ13C and δ15N did not explain variation in THg concentrations in the Russian bears. Total Hg levels were higher in northwest compared to southeast Svalbard. δ13C and δ15N values did not show any spatial pattern in the Norwegian Arctic. Total Hg concentrations adjusted for feeding ecology showed similar spatial trends as the measured concentrations. In contrast, within the Russian Arctic, THg levels were rather uniformly distributed, whereas δ13C values increased towards the east and south. The results indicate that Hg exposure in Norwegian and Russian polar bears is at the lower end of the pan-Arctic spectrum, and its spatial variation in the Norwegian and Russian Arctic is not driven by the feeding ecology of polar bears.

Migratory bird species may serve as vectors of contaminants to Antarctica through the local deposition of guano, egg abandonment, or mortality. To further investigate this chemical input pathway, we examined the contaminant burdens and profiles of the migratory South polar skua (Catharacta maccormicki) and compared them to the endemic Adélie penguin (Pygoscelis adeliae). A range of persistent organic pollutants were targeted in muscle and guano to facilitate differentiation of likely exposure pathways. A total of 56 of 65 targeted analytes were detected in both species, but there were clear profile and magnitude differences between the species. The South polar skua and Adélie penguin muscle tissue burdens were dominated by p,p′-dichlorodiphenyldichloroethylene (mean 5600 ng g−1 lw and 330 ng g−1 lw respectively) and hexachlorobenzene (mean 2500 ng g−1 lw and 570 ng g−1 lw respectively), a chemical profile characteristic of the Antarctic and Southern Ocean region. Species profile differences, indicative of exposure at different latitudes, were observed for polychlorinated biphenyls (PCBs), with lower chlorinated congeners and deca-chlorinated PCB-209 detected in South polar Skua, but not in Adélie penguins. Notably, the more recently used perfluoroalkyl substances and the brominated flame retardants, hexabromocyclododecane and tetrabromobisphenol A, were detected in both species. This finding suggests local exposure, given the predicted slow and limited long-range environmental transport capacity of these compounds to the eastern Antarctic sector.

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.

Mercury has become a ubiquitous hazardous element even ending up in pristine areas such as the Arctic, where it biomagnifies and leaves especially top predators vulnerable to potential health effects. Here we investigate total mercury (THg) concentrations and dietary proxies for trophic position and habitat foraging (δ15N and δ13C, respectively) in fur of 30 Arctic wolves collected during 1869–1998 in the Canadian High Arctic and Greenland. Fur THg concentrations (mean ± SD) of 1.46 ± 1.39 μg g −1 dry weight are within the range of earlier reported values for other Arctic terrestrial species. Based on putative thresholds for Hg-mediated toxic health effects, the studied Arctic wolves have most likely not been at compromised health. Dietary proxies show high dietary plasticity among Arctic wolves deriving nutrition from both marine and terrestrial food sources at various trophic positions. Variability in THg concentrations seem to be related to the wolves' trophic position rather than to different carbon sources or regional differences (East Greenland, the Foxe Basin and Baffin Bay area, respectively). Although the present study remains limited due to the scarce, yet unique historic study material and small sample size, it provides novel information on temporal and spatial variation in Hg pollution of remote Arctic species.

The Green Edge project was designed to investigate the onset, life, and fate of a phytoplankton spring bloom (PSB) in the Arctic Ocean. The lengthening of the ice-free period and the warming of seawater, amongst other factors, have induced major changes in Arctic Ocean biology over the last decades. Because the PSB is at the base of the Arctic Ocean food chain, it is crucial to understand how changes in the Arctic environment will affect it. Green Edge was a large multidisciplinary, collaborative project bringing researchers and technicians from 28 different institutions in seven countries together, aiming at understanding these changes and their impacts on the future. The fieldwork for the Green Edge project took place over two years (2015 and 2016) and was carried out from both an ice camp and a research vessel in Baffin Bay, in the Canadian Arctic. This paper describes the sampling strategy and the dataset obtained from the research cruise, which took place aboard the Canadian Coast Guard ship (CCGS) Amundsen in late spring and early summer 2016. The sampling strategy was designed around the repetitive, perpendicular crossing of the marginal ice zone (MIZ), using not only ship-based station discrete sampling but also high-resolution measurements from autonomous platforms (Gliders, BGC-Argo floats …) and under-way monitoring systems. The dataset is available at https://doi.org/10.17882/86417 (Bruyant et al., 2022).

Using whole mitochondrial DNA sequences from 89 White-tailed Eagles (Haliaeetus albicilla) sampled from Iceland, Greenland, Norway, Denmark and Estonia between 1990 and 2018, we investigate the mitogenomic variation within and between countries. We show that there is a substantial population differentiation between the countries, reflecting similar major phylogeographic patterns obtained previously for the control region of the mitochondria, which suggested two main refugia during the last glacial period. Distinct mitogenomic lineages are observed within countries with divergence times exceeding the end of the last glacial period of the Ice Age. Deviations from neutrality indicate that these lineages have been maintained by natural selection and there is an excess of segregating amino acids in comparison with number of fixations suggesting a large load of deleterious mutations. The maintenance of the distinct mitogenic lineages within countries inflates our estimates of divergence times.

Insight into processes determining the exposure of organohalogenated contaminants (OHCs) in wildlife might be gained from comparing predators in different ecosystems. This study compared two avian predator species with similar food chain lengths: the goldeneye duck (Bucephala clangula) and the tawny owl (Strix aluco) breeding in adjacent freshwater- and terrestrial ecosystems in central Norway. We measured lipophilic organochlorines (OCs) and protein-bound perfluorinated substances (PFASs) in eggs of the two species over 21 years (1999–2019). Across years, the proportional distribution of OCs (∼90% of the ΣOHC load) relative to PFASs (∼10%) was similar in the two species. Moreover, ΣOC concentrations were similar between the species, but PFAS compounds were 2–12 times higher in the goldeneyes than in tawny owls. OC-pesticides dominated in tawny owls (∼60% of ΣOC), whereas persistent polychlorinated biphenyl (PCBs) congeners were the main OC components in goldeneyes (∼70% of ΣOC). The lipid-normalized concentrations of most OC-pesticides and the less persistent PCB101 declined significantly in both species. Hexachlorobenzene (HCB), p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE), and more persistent PCBs decreased in tawny owls, while they tended to increase in goldeneyes. The increase in HCB was particulary robust. Among the PFASs, contrasted temporal trends were found across the species for four out of 11 compounds: PFOS declined while most perfluorocarboxylic acids (PFCAs) increased in tawny owls. In contrast, most PFASs were stable in goldeneyes. Moreover, there was no annual covariance between the OHC exposure in the two species: i.e., high concentrations in one species in a given year did not translate into high concentrations in the other. Hence, the two avian predators in adjacent ecosystems seem to be subject to different processes determining the OHC exposure, probably related to variation in diet and climate, long-range transport of different contaminants, and emissions of pollution locally.

Using whole genome shotgun sequences from 92 white-tailed eagles (Haliaeetus albicilla) sampled from Greenland, Iceland, Norway, Denmark, Estonia, and Turkey between 1885-1950 and after 1990, we investigate the genomic variation within countries over time, and between countries. Clear genetic differentiation is observed between samples from the different countries, with the largest differences between the island and mainland populations, and indications that the island populations share the most recent ancestry with the Norwegian population. We find signs of strong inbreeding in the island populations. Further, temporal differences are observed in some populations, for example, replacement of the Danish gene pool following its population’s extinction in the early 20th century, as well as a change in the genetic diversity of the Icelandic population following a severe bottleneck during the last century, all of which could warrant a further conservation effort in Iceland. More generally, all populations show a decline in effective population size, which may have been shaped by I) distinct refugia during the last glacial period, II) population divergence following the colonization of the deglaciated areas ~10,000 years ago, III) human population expansion and e.g., settlement in Iceland ~1,100 years ago, and IV) human persecution and toxic pollutants during the last two centuries.

International audience; Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, representing a larger portion of the Arctic than during previous AMAP assessments now also including parts of the Russian Arctic. To assess risk to birds, we used Hg toxicity benchmarks established for blood and converted to egg, liver, and feather tissues. Several Arctic seabird populations showed Hg concentrations that exceeded toxicity benchmarks, with 50 % of individual birds exceeding the "no adverse health effect" level. In particular, 5 % of all studied birds were considered to be at moderate or higher risk to Hg toxicity. However, most seabirds (95 %) were generally at lower risk to Hg toxicity. The highest Hg contamination was observed in seabirds breeding in the western Atlantic and Pacific Oceans. Most Arctic shorebirds exhibited low Hg concentrations, with approximately 45 % of individuals categorized at no risk, 2.5 % at high risk category, and no individual at severe risk. Although the majority Arctic-breeding seabirds and shorebirds appeared at lower risk to Hg toxicity, recent studies have reported deleterious effects of Hg on some pituitary hormones, genotoxicity, and reproductive performance. Adult survival appeared unaffected by Hg exposure, although long-term banding studies incorporating Hg are still limited. Although Hg contamination across the Arctic is considered low for most bird species, Hg in combination with other stressors, including other contaminants, diseases, parasites, and climate change, may still cause adverse effects. Future investigations on the global impact of Hg on Arctic birds should be conducted within a multi-stressor framework. This information helps to address Article 22 (Effectiveness Evaluation) of the Minamata Convention on Mercury as a global pollutant.

The occurrence of organohalogenated compounds (OHCs) in wildlife has received considerable attention over the last decades. Among the matrices used for OHCs biomonitoring, feathers are particularly useful as they can be collected in a minimally or non-invasive manner. In this study, concentrations of various legacy OHCs -polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)-, as well as emerging OHCs -per- and polyfluoroalkyl substances (PFAS) and organophosphate ester flame retardants (OPEs)- were determined in feathers of 72 Eurasian eagle-owls (Bubo bubo) from Norway, with the goal of studying spatiotemporal variation using a non-invasive approach. Molted feathers were collected at nest sites from northern, central and southern Norway across four summers (2013-2016). Additionally, two museum-archived feathers from 1979 to 1989 were included. Stable carbon (δ13C) and nitrogen isotopes (δ15N) were used as dietary proxies. In total, 11 PFAS (sum range 8.25-215.90 ng g

Organophosphate flame retardants (PFRs) have largely replaced the market of polybrominated diphenyl ethers (PBDEs). Concerns about PFR contamination and its impact on human health have consequently increased. A comprehensive investigation on the human exposure pathways to PFRs is to be endeavoured. This study investigated the occurrence of PFR metabolites in human urine, serum and hair, correlating them with external exposure data that was presented in our previous studies. Participants from Oslo (n = 61) provided a set of samples, including dust, air, handwipes, food, urine, serum and hair. Associations between PFR metabolites analyzed in the biological samples and the PFRs in environmental samples were explored. Different sampling strategies for dosimeters (e.g. floor/surface dust, personal/stationary air) were also compared to understand which is better for predicting human exposure to PFRs. Seven out of the eleven target PFR metabolites, including diphenyl phosphate (DPHP) and bis(1-chloro-2-propyl)-1-hydroxy-2-propyl phosphate (BCIPHIPP), were frequently detected (DF > 30%) in urine. DPHP was the most frequently detected metabolite in both serum and hair. Several PFR metabolites had higher levels in morning urine than in afternoon urine. Floor dust appeared to be a better proxy for estimating PFR internal exposure than surface dust, air, and handwipes. Some PFRs in handwipes and air were also correlated with their metabolites in urine and hair. Age, beverage consumption and food consumption were negatively associated with DPHP levels in urine. Discrepancies observed between the external and internal exposure for some PFRs call for further investigation on PFR bioaccessibility and clearance. Keywords: PFR metabolites, Exposure pathways, Dust, Air, Handwipe, Urine

Short-, medium-, and long-chain chlorinated paraffins (SCCPs, MCCPs, and LCCPs) have a wide range of physical-chemical properties, indicating their varying bioaccumulation tendencies in marine and terrestrial ecosystems. However, there are few empirical data to reveal such bioaccumulation tendencies. In this study, we analyzed SCCPs, MCCPs, and LCCPs in samples from 18 species at both low and high trophic levels of marine and terrestrial ecosystems from the Scandinavian region collected during the past decade. These included fish, seabirds, marine mammals, and terrestrial birds and mammals. SCCPs, MCCPs, and LCCPs were present in all the species, with concentrations ranging from 26-1500, 30-1600, 6.0-1200 ng/g lipid, respectively. Although MCCPs and SCCPs predominated in most species, many terrestrial species had generally higher concentrations of LCCPs than marine species. Terrestrial raptors in particular accumulated higher concentrations of LCCPs, including C 24/25 - which are predominant among very-long-chain components. LCCP concentrations were highest and predominated (55% of total CPs) in peregrine falcons in this study, which is the first report where concentrations of LCCPs surpass those of SCCPs and MCCPs in wildlife. The results also indicate biomagnification of SCCPs, MCCPs, and LCCPs in both marine and terrestrial food chains, but in-depth studies of specific food webs are needed.

A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geographic focus is on the Baltic Sea, while data from the same species in adjacent waters, such as the Greater North Sea and North Atlantic, were included for comparative purposes. For marine mammals, 23% of the groups, each composing individuals of a specific sex and maturity from the same species in a specific study region, showed Hg-concentrations within the High Risk Category (HRC) and Severe Risk Category (SRC). The corresponding percentages for seabirds, fish and bivalves were 2.7%, 25% and 8.0%, respectively, although fish and bivalves were not represented in the SRC. Juveniles from all species showed to be at no or low risk. In comparison to the same species in the adjacent waters, i.e. the Greater North Sea and the North Atlantic, the estimated risk for Baltic populations is not considerably higher. These findings suggest that over the past few decades the Baltic Sea has improved considerably with respect to presenting Hg exposure to its local species, while it does still carry a legacy of elevated Hg levels resulting from high neighbouring industrial and agricultural activity and slow water turnover regime.

Resumen del póster presentado al SETAC Europe 31st Annual Meeting, celebrado de forma virtual del 3 al 6 de mayo de 2021., As a key part of the European Green Deal, the EU Chemicals Strategy aims for a non-toxic environment. A key challenge in this respect is to apply biomonitoring data in toxicological and ecotoxicological risk assessment to inform better management of chemicals in Europe. Raptors (birds of prey, owls and falcons) are widely used as sentinel species in monitoring programs and are particularly well-suited to contaminant monitoring. Delivering relevant contaminant data at pan-European scale requires the development of a pan-European network that brings together fieldworkers, sample collections and analytical laboratories, and of frameworks for the gathering, storage and analysis of raptor samples, together with related capacity-building and sharing of best practice. This challenge is being addressed by the COST Action European Raptor Biomonitoring Facility (https://erbfacility.eu/) building on the precursor Networking Programme Research and Monitoring for and with Raptors in Europe (EURAPMON; http://www.eurapmon.net/). This poster introduces a schematic sampling protocol for contaminant monitoring in raptors. The protocol provides best-practice guidance in a format accessible to both professionals and volunteers. The protocol aims to enhance sampling capabilities across Europe, ensure appropriate quality of samples and facilitate harmonization of procedures to maximize the reliability, comparability and interoperability of resulting contaminant data. The protocol starts with each matrix type, including sample types that are collected both during active (samples from captured birds and monitored nests) and passive (samples from dead birds and deserted nests) sampling. For each sample type (whole blood, plasma, serum, deserted or addled eggs, feathers, preen oil, regurgitated pellets, prey remains, gastric content and internal tissues), a specific protocol offering additional information is provided (e.g., collecting procedure, volume/mass of sample needed for contaminant monitoring, container types to conserve the sample, transport and storage conditions). The full protocol can be found online (https://doi.org/10.1007/s13280-020-01341-9)., European Raptor Biomonitoring Facility COST Action (CA16224) is supported by COST (European Cooperation in Science and Technology). Silvia Espín is supported by Ministerio de Ciencia, Innovación y Universidades (IJCI-2017-34653).

The occurrence of organohalogenated compounds (OHCs) in wildlife has received considerable attention over the last decades. Among the matrices used for OHCs biomonitoring, feathers are particularly useful as they can be collected in a minimally or non-invasive manner. In this study, concentrations of various legacy OHCs –polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs)–, as well as emerging OHCs –per- and polyfluoroalkyl substances (PFAS) and organophosphate ester flame retardants (OPEs)– were determined in feathers of 72 Eurasian eagle-owls (Bubo bubo) from Norway, with the goal of studying spatiotemporal variation using a non-invasive approach. Molted feathers were collected at nest sites from northern, central and southern Norway across four summers (2013–2016). Additionally, two museum-archived feathers from 1979 to 1989 were included. Stable carbon (δ13C) and nitrogen isotopes (δ15N) were used as dietary proxies. In total, 11 PFAS (sum range 8.25–215.90 ng g− 1), 15 PCBs (4.19–430.01 ng g− 1), 6 OCPs (1.48–220.94 ng g− 1), 5 PBDEs (0.21–5.32 ng g− 1) and 3 OPEs (4.49–222.21 ng g− 1) were quantified. While we observed large variation in the values of both stable isotopes, suggesting a diverse diet of the eagle owls, only δ13C seemed to explain variation in PFAS concentrations. Geographic area and year were influential factors for δ15N and δ13C. Considerable spatial variation was observed in PFAS levels, with the southern area showing higher levels compared to northern and central Norway. For the rest of OHCs, we observed between-year variations; sum concentrations of PCBs, OCPs, PBDEs and OPEs reached a maximum in 2015 and 2016. Concentrations from 1979 to 1989 were within the ranges observed between 2013 and 2016. Overall, our data indicate high levels of legacy and emerging OHCs in a top predator in Norway, further highlighting the risk posed by OHCs to wildlife. Keywords: Bird of prey Feathers Isotopes OPE POP PFAS

While new chemicals have replaced major toxic legacy contaminants such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), knowledge of their current levels and biomagnification potential in Baltic Sea biota is lacking. Therefore, a suite of chemicals of emerging concern, including organophosphate esters (OPEs), short-chain, medium-chain and long-chain chlorinated paraffins (SCCPs, MCCPs, LCCPs), halogenated flame retardants (HFRs), and per- and polyfluoroalkyl substances (PFAS), were analysed in blue mussel (Mytilus edulis), viviparous eelpout (Zoarces viviparus), Atlantic herring (Clupea harengus), grey seal (Halichoerus grypus), harbor seal (Phoca vitulina), harbor porpoise (Phocoena phocoena), common eider (Somateria mollissima), common guillemot (Uria aalge) and white-tailed eagle (Haliaeetus albicilla) from the Baltic Proper, sampled between 2006 and 2016. Results were benchmarked with existing data for legacy contaminants. The mean concentrations for ΣOPEs ranged from 57 to 550 ng g −1 lipid weight (lw), for ΣCPs from 110 to 640 ng g −1 lw for ΣHFRs from 0.42 to 80 ng g −1 lw, and for ΣPFAS from 1.1 to 450 ng g −1 wet weight. Perfluoro-4-ethylcyclohexanesulfonate (PFECHS) was detected in most species. Levels of OPEs, CPs and HFRs were generally similar or higher than those of polybrominated diphenyl ethers (PBDEs) and/or hexabromocyclododecane (HBCDD). OPE, CP and HFR concentrations were also similar to PCBs and DDTs in blue mussel, viviparous eelpout and Atlantic herring. In marine mammals and birds, PCB and DDT concentrations remained orders of magnitude higher than those of OPEs, CPs, HFRs and PFAS. Predator-prey ratios for individual OPEs (0.28–3.9) and CPs (0.40–5.0) were similar or somewhat lower than those seen for BDE-47 (5.0–29) and HBCDD (2.4–13). Ratios for individual HFRs (0.010–37) and PFAS (0.15–47) were, however, of the same order of magnitude as seen for p,p′-DDE (4.7–66) and CB-153 (31–190), indicating biomagnification potential for many of the emerging contaminants. Lack of toxicity data, including for complex mixtures, makes it difficult to assess the risks emerging contaminants pose. Their occurence and biomagnification potential should trigger risk management measures, particularly for MCCPs, HFRs and PFAS.

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.

Here we review contaminant exposure and related health effects in six selected Baltic key species. Sentinel species included are common eider, white-tailed eagle, harbour porpoise, harbour seal, ringed seal and grey seal. The review represents the first attempt of summarizing available information and baseline data for these biomonitoring key species exposed to industrial hazardous substances focusing on anthropogenic persistent organic pollutants (POPs). There was only limited information available for white-tailed eagles and common eider while extensive information exist on POP exposure and health effects in the four marine mammal species. Here we report organ-tissue endpoints (pathologies) and multiple biomarkers used to evaluate health and exposure of key species to POPs, respectively, over the past several decades during which episodes of significant population declines have been reported. Our review shows that POP exposure affects the reproductive system and survival through immune suppression and endocrine disruption, which have led to population-level effects on seals and white-tailed eagles in the Baltic. It is notable that many legacy contaminants, which have been banned for decades, still appear to affect Baltic wildlife. With respect to common eiders, changes in food composition, quality and contaminant exposure seem to have population effects which need to be investigated further, especially during the incubation period where the birds fast. Since new industrial contaminants continuously leak into the environment, we recommend continued monitoring of them in sentinel species in the Baltic, identifying possible effects linked to climate change, and modelling of population level effects of contaminants and climate change.

Temporal trends of total mercury (THg) were examined in female polar bear (Ursus maritimus) hair (n = 199) from the Barents Sea in 1995-2016. In addition, hair values of stable isotopes (n = 190-197) of carbon (δ13C), sulfur (δ34S), and nitrogen (δ15N) and information on breeding status, body condition, and age were obtained. Stable isotope values of carbon and sulfur reflect dietary source (e.g., marine vs terrestrial) and the nitrogen trophic level. Values for δ13C and δ34S declined by -1.62 and -1.18‰ over the time of the study period, respectively, while values for δ15N showed no trend. Total Hg concentrations were positively related to both δ13C and δ34S. Yearly median THg concentrations ranged from 1.61 to 2.75 μg/g and increased nonlinearly by 0.86 μg/g in total over the study. Correcting THg concentrations for stable isotope values of carbon and sulfur and additionally breeding status and age slightly accelerated the increase in THg concentrations; however, confidence intervals of the raw THg trend and the corrected THg trend had substantial overlap. The rise in THg concentrations in the polar bear food web was possibly related to climate-related re-emissions of previously stored Hg from thawing sea-ice, glaciers, and permafrost.

Temporal trends of total mercury (THg) were examined in female polar bear (

Naturally occurring radionuclides, in particular, polonium-210 (210Po), have a greater contribution than anthropogenic radionuclides to the annual effective dose received by the general public due to consumption of seafood. Knowledge of potential trophic sources and transfer of 210Po to seabird species and subsequently to the Greenlandic people is, however, still poor. Here, we assess the transfer of 210Po and 210Pb to seabirds sampled during autumn and winter 2017 and 2018 in Greenland and provide a dose assessment. The activity concentrations of 210Po in muscle and liver, respectively, ranged from 0.2 ± 0.1 Bq kg−1 w.w. in glaucous gull (Larus hyperboreus) to 21.2 ± 22.6 Bq kg−1 w.w. in thick-billed murre (Uria lomvia) and from 32.0 ± 9.4 Bq kg−1 w.w. in common eider (Somateria mollissima) to 40.5 ± 49.0 Bq kg−1 w.w. in thick-billed murre. 210Po was non-uniformly distributed in the body of thick-billed murre. Kidneys and feathers showed higher 210Po activity concentrations than heart and bone. The 210Po/210Pb activity concentration ratios are higher than unity, indicating that 210Po is preferentially taken up by seabirds compared to its progenitor 210Pb. The derived annual absorbed dose from 210Po to the whole body of thick-billed murre was 6.4 × 102 ± 3.0 × 102 μGy. The annual effective dose to the average adult and representative person in Greenland due to ingestion of 210Po in seabirds was estimated to 13.0 μSv and 57.0 μSv, respectively. This derived dose is low and poses a slight risk, and risk communication is therefore deemed unnecessary.

The white-tailed eagle (

The biogeochemistry of deep-sea trenches is strongly influenced by their V-shape topography and tectonic position in the ocean, leading to a focusing effect of sediment and organic matter into the trench centre. Recent findings showed elevated mineralization rates in trench sediments, suggesting both high carbon turnover and organic matter degradation rates. As persistent organic pollutants (POPs) favourably partition to organic matter, deep-sea trenches act as a sink for these substances. Composition, source and age of the organic matter have been shown to have a significant influence on contaminant dynamics in sediment from more shallow regions. Also, the trophic status of marine systems plays a significant role in transport of POPs from air to water and to sediment. However, knowledge about organic pollutants in deep-sea environments is scarce. In the present study, sediment samples from two deep-sea trenches with different trophic states and deposition regimes are analysed for POPs with a wide range of physicochemical properties. Concentrations will be compared between the semi-eutrophic Atacama and the oligotrophic Kermadec Trench. Sampling of sediment cores was performed at the slope, abyssal plain and trench at Atacama (depth between 2,500 and 8,000m) and at the abyssal plain and trench at Kermadec (depth of 6,000 and 9,600m). The total organic carbon content largely varied between 0.3 and 2.1% at different sites at the Atacama Trench, while values were more homogeneous at the Kermadec Trench (around 0.3%). Preliminary results from the Atacama samples demonstrate concentrations of PCBs at the pg g-1 dw level, and indicate highest concentrations to occur at the highest depth in the trench. Low sedimentation- and high mineralization rates in the trench centre, as well as the funnel-effect from the topology may explain these differences.

Understanding the spatiotemporal patterns of legacy organochlorines (OCs) is often difficult because monitoring practices differ among studies, fragmented study periods, and unaccounted confounding by ecological variables. We therefore reconstructed long-term (1939–2015) and large-scale (West Greenland, Norway, and central Sweden) trends of major legacy OCs using white-tailed eagle (Haliaeetus albicilla) body feathers, to understand the exposure dynamics in regions with different contamination sources and concentrations, as well as the effectiveness of legislations. We included dietary proxies (δ13C and δ15N) in temporal trend models to control for potential dietary plasticity. Consistent with the hypothesised high local pollution sources, levels of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and hexachlorocyclohexanes (HCHs) in the Swedish subpopulation exceeded those in the other subpopulations. In contrast, chlordanes (CHLs) and hexachlorobenzene (HCB) showed higher concentrations in Greenland, suggesting the importance of long-range transport. The models showed significantly decreasing trends for all OCs in Sweden in 1968–2011 except for CHLs, which only decreased since the 1980s. Nevertheless, median concentrations of DDTs and PCBs remained elevated in the Swedish subpopulation throughout the 1970s, suggesting that the decreases only commenced after the implementation of regulations during the 1970s. We observed significant trends of increasing concentrations of PCBs, CHLs and HCB in Norway from the 1930s to the 1970s/1980s and decreasing concentrations thereafter. All OC concentrations, except those of PCBs were generally significantly decreasing in the Greenland subpopulation in 1985-2013. All three subpopulations showed generally increasing proportions of the more persistent compounds (CB 153, p.p′-DDE and β-HCH) and decreasing proportions of the less persistent ones (CB 52, p.p′-DDT, α- and γ-HCH). Declining trends of OC concentrations may imply the decreasing influence of legacy OCs in these subpopulations. Finally, our results demonstrate the usefulness of archived museum feathers in retrospective monitoring of spatiotemporal trends of legacy OCs using birds of prey as sentinels. This article is available under the Creative Commons CC-BY-NC-ND license and permits non-commercial use of the work as published, without adaptation or alteration provided the work is fully attributed.

The white-tailed eagle (Haliaeetus albicilla) in Scandinavia has suffered from impaired reproduction due to high exposure to industrial pollution between the 1960s and 1980s. While population numbers are rising again, new contaminants, such as per- and polyfluoroalkyl substances (PFAS), are increasingly found in high trophic avifauna and are of concern to potentially impact once again on population health. In the present study, we examined PFAS levels in plasma of white-tailed eagle nestlings from northern Norway over the last decade (2008-2017). While PFOA and PFNA exposure did not follow a significant time trend, PFOS and PFHxS concentrations decreased over time, and ≥C11 perfluorinated carboxylic acids only seem to level off during the last four years. This may in fact be the first evidence for a change in the trend for some of these compounds. Furthermore, since several PFAS are expected to be highly present in aqueous film-forming foams used at airports, we also investigate the potential of the two main airports in the region to act as hotspots for PFAS. Our results indeed show decreasing exposure to PFOA with distance to the airports. Altogether, our results seem to show that legislation actions are effective, and continued concern for PFAS exposure of high trophic wildlife is still warranted, even in the northern environment.

In this study, we analyzed biochemical parameters and the body masses of 14 incubating Common Eiders (Somateria mollissima) breeding on Christiansø in the Baltic Sea from April to May 2015. The eiders were examined and sampled on days 4 and 24, corresponding to early and late incubation. In comparison to reference values, concentrations of alkaline phosphatase (161%), phosphorus (33%), and calcium (44%) were all significantly increased on day 4 by 33–161% due to egg production (p < 0.05). On day 24, we observed a significant loss of body mass (28%) compared to day 4 (p < 0.05). The average plasma concentrations of fructosamine (1-amino-1-deoxy-d-fructose, 21%), amylase (54%), albumin (30%), and total protein declined significantly (all p < 0.05). These declines resemble those seen for other avian species in which the female is the sole incubator, suggesting reduced food intake during the incubation period. A decline in total protein and albumin from day 4 to day 24 (18–30%) is indicative of stage III protein metabolism. Nonetheless, stable concentrations of urea, sodium, and potassium suggest that the incubating females were significantly hydrated. The change in the plasma albumin:globulin ratio from day 4 (0.82) to day 24 (0.57) may imply slight immune suppression, which is supported by the observation of a mass mortality incident shortly after the studied incubation period. These biochemical observations may add to our understanding of the recurrent mortality events that strike without warning in the declining Baltic eider population.