Toxicology Laboratory, Section of Advanced Drug Analysis, Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen Ø, Denmark. Electronic address: email@example.com.
This review addresses biological effects of anthropogenic organohalogenated compounds in the arctic fox (Vulpes lagopus). When considering the current levels, spatial and tissue distributions of selected organic pollutants in arctic fox subpopulations, especially the Svalbard based populations accumulate high levels. The dominating contaminant groups are the polychlorinated biphenyls (PCBs) and chlordanes (CHLs), which reach high levels in adipose tissues, adrenals and liver. Recent controlled exposure studies on domesticated arctic fox and Greenland sledge dogs, show adverse health effects associated with OC concentrations lower than those measured in free-ranging populations. This indicates that especially populations at Svalbard may be at risk of experiencing OC related effects. The arctic fox as such may be an overlooked species in the Arctic Monitoring and Assessment Programs and it would add further information about pollution in the Arctic to include this species in the monitoring program.
Persistent organic pollutants (POPs) are found in high concentrations in the Artic. Polar bears (Ursus maritimus) are one of the most exposed mammals in the Arctic and are thereby vulnerable to reproductive disruption. The aim of this study was to investigate male polar bear reproduction based on a detailed evaluation of testis histology and to assess possible effects of environmental chemicals on male polar bear reproduction. Reproductive groups that were identified based on histology were as follows: actively reproductive (REP), non-reproductive either with degenerated testes (DEG), undeveloped seminiferous tubules (UND), or morphology in-transition (INT). Categorization into these groups was supported by significant differences in testis and baculum measurements among REP, DEG, and UND, as well as differences in the area and diameter of seminiferous tubules among REP, DEG, and UND. These results show that it is possible to identify the reproductive stage in polar bears even if capture date and or age is lacking. Based on testis morphology we suggest that adult male polar bears from East Greenland have active spermatogenesis in February to June, and inactive degenerated testes in August to January. January to February was the main period of reproductive transition, characterised by a shift between inactive and active spermatogenesis. Baculum and testis size measurements decreased significantly with increasing concentrations of the chlordane metabolite oxychlordane, suggesting a potential impact on male reproductive success. Half of the investigated polar bears in REP group displayed signs of disorganization of the spermatogenesis which might be a sign of disrupted reproduction. However, no correlations with levels of the investigated POPs were detected. Reproductive organ measurements in polar bears differed significantly between REP and DEG groups, which cannot be explained by age, and therefore should be considered when investigating the effect of POPs on male reproduction.
Polar bears (Ursus maritimus) from East Greenland and Svalbard exhibited very high concentrations of polychlorinated biphenyls (PCBs) in the 1980s and 1990s. In Svalbard, slow population growth during that period was suspected to be linked to PCB contamination. In this case study, we explored how PCBs could have impacted polar bear population growth and/or male reproductive success in Svalbard during the mid-1990s by reducing the fertility of contaminated males. A dose-response relationship linking the effects of PCBs to male polar bear fertility was extrapolated from studies of the effects of PCBs on sperm quality in rodents. Based on this relationship, an individual-based model of bear interactions during the breeding season predicted fertilization success under alternative assumptions regarding male-male competition for females. Contamination reduced pregnancy rates by decreasing the availability of fertile males, thus triggering a mate-finding Allee effect, particularly when male-male competition for females was limited or when infertile males were able to compete with fertile males for females. Comparisons of our model predictions on age-dependent reproductive success of males with published empirical observations revealed that the low representation of 10-14-year-old males among breeding males documented in Svalbard in mid-1990s could have resulted from PCB contamination. We conclude that contamination-related male infertility may lead to a reduction in population growth via an Allee effect. The magnitude of the effect is largely dependent on the population-specific mating system. In eco-toxicological risk assessments, appropriate consideration should therefore be given to negative effects of contaminants on male fertility and male mating behaviour.
As a model of high trophic level carnivores, sledge dogs were fed from 2 to 18 months of age with minke whale blubber containing organohalogen compounds (OHC) corresponding to 128 µg PCB/day. Controls were fed uncontaminated porcine fat. Thyroid hormone levels were assessed in 7 exposed and 7 control sister bitches (sampled at age 6-18 months) and 4 exposed and 4 control pups, fed the same diet as their mothers (sampled age 3-12 months). Lower free and total T3 and T4 were seen in exposed vs. control bitches beyond 10 months of age, and total T3 was lower through 3-12 months of age in exposed pups. A negative correlation with thyroid gland weight was significant for SDDT, as was a positive association with total T3 for dieldrin. This study therefore supports observational data that OHCs may adversely affect thyroid functions, and it suggests that OHC exposure duration of 10 months or more may be required for current OHC contamination levels to result in detectable adverse effects on thyroid hormone dynamics.
The ability of animals to respond to changes in their environment is critical to their persistence. In the Arctic, climate change and mercury exposure are two of the most important environmental threats for top predators.1-3 Rapid warming is causing precipitous sea-ice loss, with consequences on the distribution, composition, and dietary ecology of species4-7 and, thus, exposure to food-borne mercury.8 Current understanding of global change and pollution impacts on Arctic wildlife relies on single-time-point individual data representing a snapshot in time. These data often lack comprehensive temporal resolution and overlook the cumulative lifelong nature of stressors as well as individual variation. To overcome these challenges, we explore the unique capacity of narwhal tusks to characterize chronological lifetime biogeochemical profiles, allowing for investigations of climate-induced dietary changes and contaminant trends. Using temporal patterns of stable isotopes (d13C and d15N) and mercury concentrations in annually deposited dentine growth layer groups in 10 tusks from Northwest Greenland (1962-2010), we show surprising plasticity in narwhal feeding ecology likely resulting from climate-induced changes in sea-ice cover, biological communities, and narwhal migration. Dietary changes consequently impacted mercury exposure primarily through trophic magnification effects. Mercury increased log-linearly over the study period, albeit with an unexpected rise in recent years, likely caused by increased emissions and/or greater bioavailability in a warmer, ice-free Arctic. Our findings are consistent with an emerging pattern in the Arctic of reduced sea-ice leading to changes in the migration, habitat use, food web, and contaminant exposure in Arctic top predators.
Although sled dogs are one of the most specialized groups of dogs, their origin and evolution has received much less attention than many other dog groups. We applied a genomic approach to investigate their spatiotemporal emergence by sequencing the genomes of 10 modern Greenland sled dogs, an ~9500-year-old Siberian dog associated with archaeological evidence for sled technology, and an ~33,000-year-old Siberian wolf. We found noteworthy genetic similarity between the ancient dog and modern sled dogs. We detected gene flow from Pleistocene Siberian wolves, but not modern American wolves, to present-day sled dogs. The results indicate that the major ancestry of modern sled dogs traces back to Siberia, where sled dog-specific haplotypes of genes that potentially relate to Arctic adaptation were established by 9500 years ago.
On 11 May 2019, the Mauna Loa, Hawaii, Earth System Research Laboratory reported the highest CO2 concentration in human meteorological history. Continuing CO2 rise will devastate ecosystems, and ice dependent species like polar bears ultimately will disappear. Commercial aviation is presently a relatively small CO2 contributor, but this CO2 intensive mode of transportation is projected to increase greatly. Scientists and conservationists are often among the most frequent of flyers, despite their recognition that emissions must be reduced. Here we illustrate the carbon footprint of air travel in terms of its impact on the sea ice habitat necessary for polar bear persistence, and suggest our colleagues reduce their air travel where-ever possible. Each metric ton of CO2 emitted melts ~3?m2 of arctic summer sea ice, and current air travel melts over 5000?m2 each year. Each scientist making the short flight from Copenhagen to Oslo to join an IUCN polar bear meeting will melt ~1?m2 of Arctic summer sea-ice. Annually hundreds of scientists and conservationists make frequent flights of much greater distances for AMAP, CAFF, IUCN, and other conservation related meetings. Much of this travel could be avoided with better planning and employing internet linkages for remote participation. When air travel, such as for necessary fieldwork, cannot be easily substituted by Web linkage, we all should search for routes and carriers allowing the lowest CO2 emissions. We encourage all of our colleagues to join 'No Fly Climate Sci' to show their commitment to CO2 reduction and learn more about doing so. As scientists, if we are serious about preserving polar bears and their Arctic sea ice habitat, we need to walk the talk and show an example for the rest of society by significantly reducing our air travel.
The bioaccumulation and biomagnification of 22 major perfluoroalkyl substances (PFAS) were investigated in tissues of polar bears (Ursus maritimus) and their major prey species, the ringed seal (Pusa hispida), from the Scoresby Sound region of East Greenland. In polar bear liver the mean S4PFSA (perfluoroalkyl sulfonic acid) concentration (C4, C6, C8 and C10) was 2611?±?202?ng/g wet weight (ww; 99% perfluorooctane sulfonate (PFOS)) and two orders of magnitude higher than the 20?±?3?ng/g ww (89% PFOS) concentration in fat. The mean S4PFSAs in seal liver was 111?±?5?ng/g ww (98% PFOS) and three orders of magnitude higher relative to the 0.05?±?0.01?ng/g ww concentration in blubber (100% perfluorohexane sulfonate). Perfluoro-1-octane sulfonamide (FOSA) was quantifiable in bear (mean 10?±?1.4?ng/g ww) and seal (mean 0.6?±?0.1?ng/g ww) liver but not in fat or blubber. The mean S13PFCAs (C4-C18; perfluoroalkyl carboxylic acids) in bear liver (924?±?71?ng/g ww) was much greater than in seal liver (74?±?6?ng/g ww). In bear fat and seal blubber, the mean S13PFCAs were 15?±?1.9 and 0.9?±?0.1?ng/g ww, respectively. Longer chain C11 to C14 PFCAs dominated in bear fat and seal blubber (60-80% of S13PFCA), whereas shorter-chain C9 to C11 PFCAs dominated in the liver (85-90% of S13PFCA). Biomagnification factors (BMFs) were orders of magnitude greater for PFHxS and C9 to C13 PFCAs when based on bear liver to seal blubber rather than bear liver to seal liver, and PFCA (C9 to C13) BMFs decreased with increasing chain length. Seal blubber to bear liver BMFs better reflects the dietary exposure relationship of PFAS between bears and seals.
Mining activities can cause adverse and long-lasting environmental impacts and detailed monitoring is therefore essential to assess the pollution status of mining impacted areas. Here we evaluated the efficacy of two predatory fish species (Gadus ogac i.e. Greenland cod and Myoxocephalus scorpius i.e. shorthorn sculpin) as biomonitors of mining derived metals (Pb, Zn, Cd and Hg) by measuring concentrations in blood, liver, muscle and otoliths along a distance gradient near the former Black Angel Pb-Zn mine (West Greenland). We detected metals in all tissues (except Cd and Hg in otoliths) and sculpin generally displayed higher concentrations than cod. For both species, concentrations were generally highest closest to the dominant pollution source(s) and gradually decreased away from the mine. The clearest gradient was observed for Pb in blood and liver (both species), and for Pb in otoliths (sculpin only). Similar to dissolved concentrations in seawater (but in contrast to bottom sediment), no significant decrease was found for Zn, Cd and Hg in any of the tissues. This demonstrates that by including tissues of blood (representing recent accumulation) and otolith (representing more long-term exposure signals) in the sampling collection, the temporal information on contaminant exposure and accumulation can be extended. We therefore conclude that both fish species are suitable as biomonitors near Arctic mine sites and, moreover, that blood and otoliths can serve as important supplementary monitoring tissues (in addition to liver and muscle traditionally sampled) as they provide extended temporal information on recent to long-term contaminant exposure.
Aarhus University, Faculty of Science and Technology, Department of Bioscience, Arctic Research Centre, Frederiksborgvej 399, 4000 Roskilde, Denmark; Greenland Institute of Natural Resources, Department of Environment and Mineral Resources, Nuuk, Greenland. Electronic address: firstname.lastname@example.org.
Few ecotoxicological studies exist on the accumulation and effects of rare earth elements (REEs) in fish, particularly on Arctic species. In southwest Greenland, there are currently several advanced exploration REE mining projects. The aim of this study was to investigate accumulation of REEs in native fish species. Juvenile arctic chars, Salvelinus alpinus, were pulse-exposed to cerium (Ce), lanthanum (La) and yttrium (Y) using an in-situ flow-through system over a period of 15?days. Results showed that the arctic char accumulated most REEs in the gills > liver > muscle. We also demonstrated the ability of the arctic char to rapidly excrete the REEs throughout the experiment, where levels of post exposure accumulation also declined throughout the period. These results demonstrate the importance of further studies on accumulation of REE in the arctic char native to the site of future mining operations. Long-term exposure will most likely result in accumulation of REEs in arctic char, and the effects and accumulation patterns of this should be explored further.