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Sample records for polar bear densities

  1. Polar Bears

    Science.gov (United States)

    Amstrup, Steven C.; Douglas, David C.; Reynolds, Patricia E.; Rhode, E.B.

    2002-01-01

    Polar bears (Ursus maritimus) are hunted throughout most of their range. In addition to hunting polar bears of the Beaufort Sea region are exposed to mineral and petroleum extraction and related human activities such as shipping road-building, and seismic testing (Stirling 1990).Little was known at the start of this project about how polar bears move about in their environment, and although it was understood that many bears travel across political borders, the boundaries of populations had not been delineated (Amstrup 1986, Amstrup et al. 1986, Amstrup and DeMaster 1988, Garner et al. 1994, Amstrup 1995, Amstrup et al. 1995, Amstrup 2000).As human populations increase and demands for polar bears and other arctic resources escalate, managers must know the sizes and distributions of the polar bear populations. Resource managers also need reliable estimates of breeding rates, reproductive intervals, litter sizes, and survival of young and adults.Our objectives for this research were 1) to determine the seasonal and annual movements of polar bears in the Beaufort Sea, 2) to define the boundaries of the population(s) using this region, 3) to determine the size and status of the Beaufort Sea polar bear population, and 4) to establish reproduction and survival rates (Amstrup 2000).

  2. Penile density and globally used chemicals in Canadian and Greenland polar bears

    DEFF Research Database (Denmark)

    Sonne, Christian; Dyck, Markus; Rigét, Frank F

    2015-01-01

    -range dispersed and to biomagnify to very high concentrations in the tissues of Arctic apex predators such as polar bears (Ursus maritimus). A major concern relating to EDCs is their effects on vital organ-tissues such as bone and it is possible that EDCs represent a more serious challenge to the species......' survival than the more conventionally proposed prey reductions linked to climate change. We therefore analyzed penile bone mineral density (BMD) as a key phenotype for reproductive success in 279 polar bear samples born 1990-2000 representing eight polar bear subpopulations. Since EDC concentrations were...... not available from the same specimens, we compared BMD with published literature information on EDC concentrations. Latitudinal and longitudinal BMD and EDC gradients were clearly observed, with Western Hudson bears having the highest BMD and lowest EDCs, and North East Greenland polar bears carrying the lowest...

  3. Size and density of East Greenland polar bear (Ursus maritimus) skulls

    DEFF Research Database (Denmark)

    Sonne, Christian; Bechshoft, Thea Ø.; Rigét, Frank F.

    2013-01-01

    density (BMD) in 87 East Greenland male polar bears (Ursus maritimus) sampled in the time period of 1892-2010. The purpose of the study was to investigate if these measures are potential candidates as indicators for stress associated with climate change and long-range transported toxic industrial...... polar bear skulls continue in order to further explore how CBL and BMD reflect individual and population response upon exposure to environmental stress. (C) 2013 Elsevier Ltd. All rights reserved....

  4. Individual effects of seasonal changes, visitor density, and concurrent bear behavior on stereotypical behaviors in captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Kelly, Krista R; Harrison, Michelle L; Size, Daniele D; MacDonald, Suzanne E

    2015-01-01

    Stereotypical behaviors in captive polar bears (Ursus maritimus) can be detrimental to their welfare. These behaviors can be reduced through enrichment programs but are often not completely eliminated, so identifying potential triggers is important. The present study investigated the influences of seasonal changes, visitor density, and concurrent bear activity on stereotypical behaviors exhibited by 3 captive polar bears at the Toronto Zoo. All bears exhibited these behaviors; however, individual differences were found in duration and form. The male exhibited less stereotypical behavior during spring, and the females exhibited less stereotypical behavior during winter. An increase in visitor density was associated with more stereotypical behavior in 1 female but less stereotypical behavior in the other 2 bears. All bears engaged in more stereotypical behaviors when the other bears were inactive, and 1 female engaged in more stereotypical behaviors when the other bears were out of sight. Further, when conspecifics were active, all bears engaged in less stereotypical behaviors. Given the variability among individual bears, future enrichment programs must be tailored to the needs of individuals to maximize efficacy.

  5. Penile density and globally used chemicals in Canadian and Greenland polar bears.

    Science.gov (United States)

    Sonne, Christian; Dyck, Markus; Rigét, Frank F; Beck Jensen, Jens-Erik; Hyldstrup, Lars; Letcher, Robert J; Gustavson, Kim; Gilbert, M Thomas P; Dietz, Rune

    2015-02-01

    Industrially produced chemicals have been a major environmental concern across our entire Globe since the onset of rapid industrial development around the early 1900. Many of the substances being used are known to be endocrine disrupting chemicals (EDCs) and are also known to be long-range dispersed and to biomagnify to very high concentrations in the tissues of Arctic apex predators such as polar bears (Ursus maritimus). A major concern relating to EDCs is their effects on vital organ-tissues such as bone and it is possible that EDCs represent a more serious challenge to the species' survival than the more conventionally proposed prey reductions linked to climate change. We therefore analyzed penile bone mineral density (BMD) as a key phenotype for reproductive success in 279 polar bear samples born 1990-2000 representing eight polar bear subpopulations. Since EDC concentrations were not available from the same specimens, we compared BMD with published literature information on EDC concentrations. Latitudinal and longitudinal BMD and EDC gradients were clearly observed, with Western Hudson bears having the highest BMD and lowest EDCs, and North East Greenland polar bears carrying the lowest BMD and highest EDCs. A BMD vs. polychlorinated biphenyls (PCB) regression analysis showed that BMD decreased as a function of the eight subpopulations' PCB concentrations and this relationship was close to being significant (p=0.10, R(2)=0.39). Risk quotient (RQ) estimation demonstrated that PCBs could be in a range that may lead to disruption of normal reproduction and development. It is therefore likely that EDCs directly affect development and bone density in polar bears. Canadian bears had in general the best health and the North East Greenland subpopulation being at the highest risk of having negative health effects. While reductions in BMD is in general unhealthy, reductions in penile BMD could lead to increased risk of species extinction because of mating and subsequent

  6. Polar bears, Ursus maritimus

    Science.gov (United States)

    Rode, Karyn D.; Stirling, Ian

    2017-01-01

    Polar bears are the largest of the eight species of bears found worldwide and are covered in a pigment-free fur giving them the appearance of being white. They are the most carnivorous of bear species consuming a high-fat diet, primarily of ice-associated seals and other marine mammals. They range throughout the circumpolar Arctic to the southernmost extent of seasonal pack ice.

  7. Climate Drives Polar Bear Origins

    Science.gov (United States)

    In their provocative analysis of northern bears (“Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage,” Reports, 20 April, p. 344), F. Hailer et al. use independent nuclear loci to show that polar bears originated during the middle Pleistocene, rather than during t...

  8. Persistent organic pollutants and penile bone mineral density in East Greenland and Canadian polar bears (Ursus maritimus) during 1996-2015

    DEFF Research Database (Denmark)

    Daugaard-Petersen, Tobias; Langebæk, Rikke; Rigét, Frank F

    2018-01-01

    Persistent organic pollutants (POPs) are long-range transported to the Arctic via atmospheric and oceanic currents, where they biomagnify to high concentrations in the tissues of apex predators such as polar bears (Ursus maritimus). A major concern of POP exposure is their physiological effects...... on vital organ-tissues posing a threat to the health and survival of polar bears. Here we examined the relationship between selected POPs and baculum bone mineral density (BMD) in the East Greenland and seven Canadian subpopulations of polar bears. BMD was examined in 471 bacula collected between years...... 1996-2015 while POP concentrations in adipose tissue were determined in 67-192 of these individuals collected from 1999 to -2015. A geographical comparison showed that baculum BMD was significantly lowest in polar bears from East Greenland (EG) when compared to Gulf of Boothia (GB), Southern Hudson (SH...

  9. Persistent organic pollutants and penile bone mineral density in East Greenland and Canadian polar bears (Ursus maritimus) during 1996-2015.

    Science.gov (United States)

    Daugaard-Petersen, Tobias; Langebæk, Rikke; Rigét, Frank F; Dyck, Markus; Letcher, Robert J; Hyldstrup, Lars; Jensen, Jens-Erik Bech; Dietz, Rune; Sonne, Christian

    2018-03-06

    Persistent organic pollutants (POPs) are long-range transported to the Arctic via atmospheric and oceanic currents, where they biomagnify to high concentrations in the tissues of apex predators such as polar bears (Ursus maritimus). A major concern of POP exposure is their physiological effects on vital organ-tissues posing a threat to the health and survival of polar bears. Here we examined the relationship between selected POPs and baculum bone mineral density (BMD) in the East Greenland and seven Canadian subpopulations of polar bears. BMD was examined in 471 bacula collected between years 1996-2015 while POP concentrations in adipose tissue were determined in 67-192 of these individuals collected from 1999 to -2015. A geographical comparison showed that baculum BMD was significantly lowest in polar bears from East Greenland (EG) when compared to Gulf of Boothia (GB), Southern Hudson (SH) and Western Hudson (WH) Bay subpopulations (all p bears as a reference group gave a T-score of -1.44 which indicate risk of osteopenia. Concentrations of ΣPCB 74 (polychlorinated biphenyls), ΣDDT 3 (dichlorodiphenyltrichloroethanes), p,p'-DDE (dichlorodiphenyldichloroethylene), ΣHCH 3 (hexachlorohexane) and α-HCH was significantly highest in EG bears while ΣPBDE (polybrominated diphenyl ethers), BDE-47 and BDE-153 was significantly highest in SH bears (all p polar bears despite the positive statistical correlations of BMD vs. POPs. Other important factors such as nutritional status, body mass and body condition was not available for the statistical modelling. Since on-going environmental changes are known to affect these, future studies need to incorporate nutritional, endocrine and genetic parameters to further understand how POP exposure may disrupt bone homeostasis and affect baculum BMD across polar bear subpopulations. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Persistent organic pollutants, skull size and bone density of polar bears (Ursus maritimus) from East Greenland 1892-2015 and Svalbard 1964-2004

    DEFF Research Database (Denmark)

    Daugaard-Petersen, Tobias; Langebæk, Rikke; Rigét, Frank F

    2018-01-01

    We investigated skull size (condylobasal length; CBL) and bone mineral density (BMD) in polar bears (Ursus maritimus) from East Greenland (n = 307) and Svalbard (n = 173) sampled during the period 1892–2015 in East Greenland and 1964–2004 at Svalbard. Adult males from East Greenland showed...... that the skull size of adult East Greenland females was negatively correlated with collection year 1892–2015 (linear regression: p = 0.06). No temporal change was found for BMD or skull size in Svalbard polar bears (ANOVA: all p > 0.05) nor was there any significant difference in BMD between Svalbard and East...... Greenland subpopulations. Skull size was larger in polar bears from Svalbard than from East Greenland (two-way ANOVA: p = 0.003). T-scores reflecting risk of osteoporosis showed that adult males from both East Greenland and Svalbard are at risk of developing osteopenia. Finally, when correcting for age...

  11. Persistent organic pollutants, skull size and bone density of polar bears (Ursus maritimus) from East Greenland 1892-2015 and Svalbard 1964-2004.

    Science.gov (United States)

    Daugaard-Petersen, Tobias; Langebæk, Rikke; Rigét, Frank F; Letcher, Robert J; Hyldstrup, Lars; Jensen, Jens-Erik Bech; Bechshoft, Thea; Wiig, Øystein; Jenssen, Bjørn Munro; Pertoldi, Cino; Lorenzen, Eline D; Dietz, Rune; Sonne, Christian

    2018-04-01

    We investigated skull size (condylobasal length; CBL) and bone mineral density (BMD) in polar bears (Ursus maritimus) from East Greenland (n = 307) and Svalbard (n = 173) sampled during the period 1892-2015 in East Greenland and 1964-2004 at Svalbard. Adult males from East Greenland showed a continuous decrease in BMD from 1892 to 2015 (linear regression: p 0.05) nor was there any significant difference in BMD between Svalbard and East Greenland subpopulations. Skull size was larger in polar bears from Svalbard than from East Greenland (two-way ANOVA: p = 0.003). T-scores reflecting risk of osteoporosis showed that adult males from both East Greenland and Svalbard are at risk of developing osteopenia. Finally, when correcting for age and sex, BMD in East Greenland polar bears increased with increasing concentrations of persistent organic pollutants (POPs) i.e. ΣPCB (polychlorinated biphenyls), ΣHCH (hexachlorohexane), HCB (hexachlorobenzene) and ΣPBDE (polybrominated diphenyl ethers) while skull size increased with ΣHCH concentrations all in the period 1999-2014 (multiple linear regression: all p < 0.05, n = 175). The results suggest that environmental changes over time, including exposure to POPs, may affect bone density and size of polar bears. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Climate Change, Polar Bears and their management

    OpenAIRE

    Derenchenko, Liza

    2010-01-01

    This is a literature study of polar bears in the context of climate change: what kind of creatures are polar bears, what are the main interpretations of current climate change, how might the polar bear adapt to these changes (feeding strategies) and how are the bears being managed (hunting)? These are relevant questions , since climate change is on the agenda, and polar bears being the apex predators of the Arctic are a key representation of the wildlife there. The third element of polar bear...

  13. Fractal analysis of polar bear hairs

    Directory of Open Access Journals (Sweden)

    Wang Qing-Li

    2015-01-01

    Full Text Available Hairs of a polar bear (Ursus maritimus are of superior properties such as the excellent thermal protection. Why do polar bears can resist such cold environment? The paper concludes that its fractal porosity plays an important role, and its fractal dimensions are very close to the golden mean, 1.618, revealing the possible optimal structure of polar bear hair.

  14. Can polar bear hairs absorb environmental energy?

    OpenAIRE

    He Ji-Huan; Wang Qing-Li; Sun Jie

    2011-01-01

    A polar bear (Ursus maritimus) has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  15. Can polar bear hairs absorb environmental energy?

    Directory of Open Access Journals (Sweden)

    He Ji-Huan

    2011-01-01

    Full Text Available A polar bear (Ursus maritimus has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

  16. Cool Polar Bears: Dabbing on the Texture

    Science.gov (United States)

    O'Connell, Jean

    2011-01-01

    In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

  17. Introgressive hybridization: brown bears as vectors for polar bear alleles.

    Science.gov (United States)

    Hailer, Frank

    2015-03-01

    The dynamics and consequences of introgression can inform about numerous evolutionary processes. Biologists have therefore long been interested in hybridization. One challenge, however, lies in the identification of nonadmixed genotypes that can serve as a baseline for accurate quantification of admixture. In this issue of Molecular Ecology, Cahill et al. (2015) analyse a genomic data set of 28 polar bears, eight brown bears and one American black bear. Polar bear alleles are found to be introgressed into brown bears not only near a previously identified admixture zone on the Alaskan Admiralty, Baranof and Chichagof (ABC) Islands, but also far into the North American mainland. Elegantly contrasting admixture levels at autosomal and X chromosomal markers, Cahill and colleagues infer that male-biased dispersal has spread these introgressed alleles away from the Late Pleistocene contact zone. Compared to a previous study on the ABC Island population in which an Alaskan brown bear served as a putatively admixture-free reference, Cahill et al. (2015) utilize a newly sequenced Swedish brown bear as admixture baseline. This approach reveals that brown bears have been impacted by introgression from polar bears to a larger extent (up to 8.8% of their genome), than previously known, including the bear that had previously served as admixture baseline. No evidence for introgression of brown bear into polar bear is found, which the authors argue could be a consequence of selection. Besides adding new exciting pieces to the puzzle of polar/brown bear evolutionary history, the study by Cahill and colleagues highlights that wildlife genomics is moving from analysing single genomes towards a landscape genomics approach. © 2015 John Wiley & Sons Ltd.

  18. Mercury in polar bears from Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Lentfer, J.W.; Galster, W.A.

    1987-04-01

    Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

  19. Polar bears and sea ice habitat change

    Science.gov (United States)

    Durner, George M.; Atwood, Todd C.; Butterworth, Andy

    2017-01-01

    The polar bear (Ursus maritimus) is an obligate apex predator of Arctic sea ice and as such can be affected by climate warming-induced changes in the extent and composition of pack ice and its impacts on their seal prey. Sea ice declines have negatively impacted some polar bear subpopulations through reduced energy input because of loss of hunting habitats, higher energy costs due to greater ice drift, ice fracturing and open water, and ultimately greater challenges to recruit young. Projections made from the output of global climate models suggest that polar bears in peripheral Arctic and sub-Arctic seas will be reduced in numbers or become extirpated by the end of the twenty-first century if the rate of climate warming continues on its present trajectory. The same projections also suggest that polar bears may persist in the high-latitude Arctic where heavy multiyear sea ice that has been typical in that region is being replaced by thinner annual ice. Underlying physical and biological oceanography provides clues as to why polar bear in some regions are negatively impacted, while bears in other regions have shown no apparent changes. However, continued declines in sea ice will eventually challenge the survival of polar bears and efforts to conserve them in all regions of the Arctic.

  20. Mercury biomagnification in polar bears ( Ursus maritimus)

    Science.gov (United States)

    Horton, T. W.; Blum, J. D.; Xie, Z.; Hren, M.; Chamberlain, C. P.

    2007-12-01

    Mercury biomagnification occurs in a variety of ecosystems resulting in greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different foodweb channels are not well known, particularly in high-latitude systems affected by atmospheric Hg deposition associated with snow and ice. Stable carbon and nitrogen isotope ratios and Hg concentrations determined for 26 late 19th and early 20th century polar bear hair specimens collected from cataloged museum collections elucidate relationships between high latitude marine foodweb structure and Hg transport pathways. Nitrogen and carbon isotopic compositions suggest that polar bears derive nutrition from both open water (pelagic) and ice associated (sympagic) foodweb channels. Correlation between Hg concentrations and nitrogen isotope compositions indicate mercury biomagnification occurred in most of the polar bears investigated. Interpretation of stable isotope based foodweb structure in concert with Hg concentrations further suggests that Hg biomagnification occurred to a greater degree in polar bears participating in pelagic foodweb channels.

  1. Is Polar Bear Hair Fiber Optic?

    Science.gov (United States)

    Koon, Daniel W.

    1998-05-01

    New direct measurement of high optical attenuation rates in polar bear hairs 2 8 dB mm in the visible and reanalysis of the data of Tributsch et al . Sol. Energy Mater. 21, 219 (1990) seem to rule out the UV waveguiding proposed by Grojean et al . Appl. Opt. 19, 339 (1980) . The case against fiber-optic polar bear hairs is summarized, and four conditions are given that any variation of the model of Grojean et al . would have to satisfy.

  2. Mass Loss Rates of Fasting Polar Bears.

    Science.gov (United States)

    Pilfold, Nicholas W; Hedman, Daryll; Stirling, Ian; Derocher, Andrew E; Lunn, Nicholas J; Richardson, Evan

    2016-01-01

    Polar bears (Ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the Arctic. As a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased. To date, there is limited empirical data with which to evaluate the potential energetic capacity of polar bears to withstand longer fasts. We measured the incoming and outgoing mass of inactive polar bears (n = 142) that were temporarily detained by Manitoba Conservation and Water Stewardship during the open-water period near the town of Churchill, Manitoba, Canada, in 2009-2014. Polar bears were given access to water but not food and held for a median length of 17 d. Median mass loss rates were 1.0 kg/d, while median mass-specific loss rates were 0.5%/d, similar to other species with high adiposity and prolonged fasting capacities. Mass loss by unfed captive adult males was identical to that lost by free-ranging individuals, suggesting that terrestrial feeding contributes little to offset mass loss. The inferred metabolic rate was comparable to a basal mammalian rate, suggesting that while on land, polar bears can maintain a depressed metabolic rate to conserve energy. Finally, we estimated time to starvation for subadults and adult males for the on-land period. Results suggest that at 180 d of fasting, 56%-63% of subadults and 18%-24% of adult males in this study would die of starvation. Results corroborate previous assessments on the limits of polar bear capacity to withstand lengthening ice-free seasons and emphasize the greater sensitivity of subadults to changes in sea ice phenology.

  3. A circumpolar monitoring framework for polar bears

    Science.gov (United States)

    Vongraven, Dag; Aars, Jon; Amstrup, Steven C.; Atkinson, Stephen N.; Belikov, Stanislav; Born, Erik W.; DeBruyn, T.D.; Derocher, Andrew E.; Durner, George M.; Gill, Michael J.; Lunn, Nicholas J.; Obbard, Martyn E.; Omelak, Jack; Ovsyanikov, Nikita; Peacock, Elizabeth; Richardson, E.E.; Sahanatien, Vicki; Stirling, Ian; Wiig, Øystein

    2012-01-01

    Polar bears (Ursus maritimus) occupy remote regions that are characterized by harsh weather and limited access. Polar bear populations can only persist where temporal and spatial availability of sea ice provides adequate access to their marine mammal prey. Observed declines in sea ice availability will continue as long as greenhouse gas concentrations rise. At the same time, human intrusion and pollution levels in the Arctic are expected to increase. A circumpolar understanding of the cumulative impacts of current and future stressors is lacking, long-term trends are known from only a few subpopulations, and there is no globally coordinated effort to monitor effects of stressors. Here, we describe a framework for an integrated circumpolar monitoring plan to detect ongoing patterns, predict future trends, and identify the most vulnerable polar bear subpopulations. We recommend strategies for monitoring subpopulation abundance and trends, reproduction, survival, ecosystem change, human-caused mortality, human–bear conflict, prey availability, health, stature, distribution, behavioral change, and the effects that monitoring itself may have on polar bears. We assign monitoring intensity for each subpopulation through adaptive assessment of the quality of existing baseline data and research accessibility. A global perspective is achieved by recommending high intensity monitoring for at least one subpopulation in each of four major polar bear ecoregions. Collection of data on harvest, where it occurs, and remote sensing of habitat, should occur with the same intensity for all subpopulations. We outline how local traditional knowledge may most effectively be combined with the best scientific methods to provide comparable and complementary lines of evidence. We also outline how previously collected intensive monitoring data may be sub-sampled to guide future sampling frequencies and develop indirect estimates or indices of subpopulation status. Adoption of this framework

  4. Polar bears: the fate of an icon.

    Science.gov (United States)

    Fitzgerald, Kevin T

    2013-11-01

    Polar bears are one of the most iconic animals on our planet. Worldwide, even people who would never see one are drawn to these charismatic arctic ice hunters. They are the world's largest terrestrial carnivore, and despite being born on land, they spend most of their lives out on the sea ice and are considered a marine mammal. Current global studies estimate there are around 20,000 animals in some 19 discrete circumpolar populations. Aside from pregnant females denning in the winter months to give birth, the white bears do not hibernate. They spend their winters on the sea ice hunting seals, an activity they are spectacularly adapted for. Research on these animals is incredibly difficult because of the inhospitable surroundings they inhabit and how inaccessible they make the bears. For many years, the sum of our understanding of the natural history of polar bears came from tracks, scats, the remains of their kills, abandoned dens, and anecdotal observations of native hunters, explorers, and early biologists. Nonetheless, the last 40 years have seen a much better picture of their biology emerge thanks to, first, dedicated Canadian researchers and, later, truly international efforts of workers from many countries. Veterinarians have contributed to our knowledge of the bears by delivering and monitoring anesthesia, obtaining blood samples, performing necropsies, investigating their reproduction, conducting radiotelemetry studies, and examining their behavior. Recently, new technologies have been developed that revolutionize the study of the lives and natural history of undisturbed polar bears. These advances include better satellite radiotelemetry equipment and the development of remote-controlled miniature devices equipped with high-definition cameras. Such new modalities provide dramatic new insights into the life of polar bears. The remarkable degree of specialized adaptation to life on the sea ice that allowed the bears to be successful is the very reason that

  5. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears

    OpenAIRE

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-01-01

    © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd. Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we...

  6. Is bone mineral composition disrupted by organochlorines in east Greenland polar bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Born, Erik W

    2004-01-01

    We analyzed bone mineral density (BMD) in skulls of polar bears (Ursus maritimus) (n = 139) from East Greenland sampled during 1892-2002. Our primary goal was to detect possible changes in bone mineral content (osteopenia) due to elevated exposure to organochlorine [polychlorinated biphenyls (PCBs.......04) and SigmaCHL (p polar...... bears may have been caused by organochlorine exposure. Udgivelsesdato: 2004-Dec...

  7. Can polar bears use terrestrial foods to offset lost ice-based hunting opportunities?

    Science.gov (United States)

    Rode, Karyn D.; Robbins, Charles T.; Nelson, Lynne; Amstrup, Steven C.

    2015-01-01

    Increased land use by polar bears (Ursus maritimus) due to climate-change-induced reduction of their sea-ice habitat illustrates the impact of climate change on species distributions and the difficulty of conserving a large, highly specialized carnivore in the face of this global threat. Some authors have suggested that terrestrial food consumption by polar bears will help them withstand sea-ice loss as they are forced to spend increasing amounts of time on land. Here, we evaluate the nutritional needs of polar bears as well as the physiological and environmental constraints that shape their use of terrestrial ecosystems. Only small numbers of polar bears have been documented consuming terrestrial foods even in modest quantities. Over much of the polar bear's range, limited terrestrial food availability supports only low densities of much smaller, resident brown bears (Ursus arctos), which use low-quality resources more efficiently and may compete with polar bears in these areas. Where consumption of terrestrial foods has been documented, polar bear body condition and survival rates have declined even as land use has increased. Thus far, observed consumption of terrestrial food by polar bears has been insufficient to offset lost ice-based hunting opportunities but can have ecological consequences for other species. Warming-induced loss of sea ice remains the primary threat faced by polar bears.

  8. Genomic evidence of geographically widespread effect of gene flow from polar bears into brown bears.

    Science.gov (United States)

    Cahill, James A; Stirling, Ian; Kistler, Logan; Salamzade, Rauf; Ersmark, Erik; Fulton, Tara L; Stiller, Mathias; Green, Richard E; Shapiro, Beth

    2015-03-01

    Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction. © 2014 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  9. Population genomics reveal recent speciation and rapid evolutionary adaptation in polar bears

    DEFF Research Database (Denmark)

    Liu, Shiping; Lorenzen, Eline D.; Fumagalli, Matteo

    2014-01-01

    Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyperlipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show...... that the species diverged only 479-343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization...... of the cardiovascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk...

  10. Polar bear attacks on humans: Implications of a changing climate

    Science.gov (United States)

    Wilder, James; Vongraven, Dag; Atwood, Todd C.; Hansen, Bob; Jessen, Amalie; Kochnev, Anatoly A.; York, Geoff; Vallender, Rachel; Hedman, Daryll; Gibbons, Melissa

    2017-01-01

    Understanding causes of polar bear (Ursus maritimus) attacks on humans is critical to ensuring both human safety and polar bear conservation. Although considerable attention has been focused on understanding black (U. americanus) and grizzly (U. arctos) bear conflicts with humans, there have been few attempts to systematically collect, analyze, and interpret available information on human-polar bear conflicts across their range. To help fill this knowledge gap, a database was developed (Polar Bear-Human Information Management System [PBHIMS]) to facilitate the range-wide collection and analysis of human-polar bear conflict data. We populated the PBHIMS with data collected throughout the polar bear range, analyzed polar bear attacks on people, and found that reported attacks have been extremely rare. From 1870–2014, we documented 73 attacks by wild polar bears, distributed among the 5 polar bear Range States (Canada, Greenland, Norway, Russia, and United States), which resulted in 20 human fatalities and 63 human injuries. We found that nutritionally stressed adult male polar bears were the most likely to pose threats to human safety. Attacks by adult females were rare, and most were attributed to defense of cubs. We judged that bears acted as a predator in most attacks, and that nearly all attacks involved ≤2 people. Increased concern for both human and bear safety is warranted in light of predictions of increased numbers of nutritionally stressed bears spending longer amounts of time on land near people because of the loss of their sea ice habitat. Improved conflict investigation is needed to collect accurate and relevant data and communicate accurate bear safety messages and mitigation strategies to the public. With better information, people can take proactive measures in polar bear habitat to ensure their safety and prevent conflicts with polar bears. This work represents an important first step towards improving our understanding of factors influencing

  11. Trichinella and polar bears: a limited risk for humans.

    Science.gov (United States)

    Dupouy-Camet, J; Bourée, P; Yera, H

    2017-07-01

    In this review, we identified 63 cases reported since World War II of human trichinellosis linked to the consumption of parasitized polar bear (Ursus maritimus) meat. This low number contrasts to the numerous cases of human trichinellosis related to consumption of the meat of black (U. americanus) or brown bears (U. arctos). The prevalence of Trichinella infection is high in bears, but larval muscular burden is usually lower in polar bears compared to other bear species. Polar bears, therefore, seem to play a limited role in the transmission of trichinellosis to humans, as native residents living in the Arctic traditionally consume well-cooked bear meat, and travellers and foreign hunters have only limited access to this protected species due to the declining polar bear population.

  12. Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.

    Science.gov (United States)

    Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Klassert, Denise; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

    2012-04-20

    Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.

  13. The Polar BEAR magnetic field experiment

    Science.gov (United States)

    Bythrow, P. F.; Potemra, T. A.; Zanetti, L. J.; Mobley, F. F.; Scheer, L.; Radford, W. E.

    1987-09-01

    The objectives and the instrumentation of the Polar BEAR magnetic field experiment are described along with the preliminary results from simultaneous measurements of Birkeland currents and UV auroral emissions. The experiment consists of an integrated sensor head, analog electronics, and digital electronics. The sensor head is a single unit containing sensor windings for each of the three orthogonal axes, oriented parrallel to the spacecraft coordinates; to minimize interference from spacecraft-generated magnetic fields, the sensor unit is located at the end of the +y solar panel. The digital electronics package is essentially identical to that flown on HILAT. A signal processor digitizes the analog outputs of the three orthogonal axes of the flux-gate magnetometer to a 13-bit resolution, yielding a magnetic field range of + or - 63,000 nT and a resolution of 15.2 nT. The full-resolution magnetic field values are recovered by data processing techniques on the ground.

  14. Is bone mineral composition disrupted by organochlorines in east Greenland polar bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Born, Erik W

    2004-01-01

    We analyzed bone mineral density (BMD) in skulls of polar bears (Ursus maritimus) (n = 139) from East Greenland sampled during 1892-2002. Our primary goal was to detect possible changes in bone mineral content (osteopenia) due to elevated exposure to organochlorine [polychlorinated biphenyls (PCBs...... bears may have been caused by organochlorine exposure. Udgivelsesdato: 2004-Dec...

  15. Gene transcription in polar bears (Ursus maritimus) from disparate populations

    Science.gov (United States)

    Bowen, Lizabeth; Miles, A. Keith; Waters, Shannon C.; Meyerson, Randi; Rode, Karyn D.; Atwood, Todd C.

    2015-01-01

    Polar bears in the Beaufort (SB) and Chukchi (CS) Seas experience different environments due primarily to a longer history of sea ice loss in the Beaufort Sea. Ecological differences have been identified as a possible reason for the generally poorer body condition and reproduction of Beaufort polar bears compared to those from the Chukchi, but the influence of exposure to other stressors remains unknown. We use molecular technology, quantitative PCR, to identify gene transcription differences among polar bears from the Beaufort and Chukchi Seas as well as captive healthy polar bears. We identified significant transcriptional differences among a priori groups (i.e., captive bears, SB 2012, SB 2013, CS 2013) for ten of the 14 genes of interest (i.e., CaM, HSP70, CCR3, TGFβ, COX2, THRα, T-bet, Gata3, CD69, and IL17); transcription levels of DRβ, IL1β, AHR, and Mx1 did not differ among groups. Multivariate analysis also demonstrated separation among the groups of polar bears. Specifically, we detected transcript profiles consistent with immune function impairment in polar bears from the Beaufort Sea, when compared with Chukchi and captive polar bears. Although there is no strong indication of differential exposure to contaminants or pathogens between CS and SB bears, there are clearly differences in important transcriptional responses between populations. Further investigation is warranted to refine interpretation of potential effects of described stress-related conditions for the SB population.

  16. Sex identification of polar bears from blood and tissue samples

    Science.gov (United States)

    Amstrup, Steven C.; Garner, G.W.; Cronin, M.A.; Patton, J.C.

    1993-01-01

    Polar bears (Ursus maritimus) can be adversely affected by hunting and other human perturbations because of low population densities and low reproduction rates. The sustainable take of adult females may be as low as 1.5% of the population. Females and accompanying young are most vulnerable to hunting, and hunters have not consistently reported the sex composition of the harvest, therefore a method to confirm the sexes of polar bears harvested in Alaska is needed. Evidence of the sex of harvested animals is often not available, but blood or other tissue samples often are. We extracted DNA from tissue and blood samples, and amplified segments of zinc finger (ZFX and ZFY) genes from both X and Y chromosomes with the polymerase chain reaction. Digestion of amplified portions of the X chromosome with the restriction enzyme HaeIII resulted in subdivision of the original amplified segment into four smaller fragments. Digestion with HaeIII did not subdivide the original segment amplified from the Y chromosome. The differing fragment sizes produced patterns in gel electrophoresis that distinguished samples from male and female bears 100% of the time. This technique is applicable to the investigation of many wildlife management and research questions.

  17. Steroid hormone profile in female polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Gustavson, Lisa; Jenssen, Bjorn Munro; Bytingsvik, Jenny

    2015-01-01

    -4 pathway in polar bears, similar to rodents. The large individual variability in steroid levels reported here most likely reflects the differences in reproductive status of the female polar bears during mating season. The steroid data establish reference values of steroid hormones and may...... is the first study to report circulating concentrations of nine steroid hormones (i.e., estrogens, androgens and progestagens) in female polar bears (Ursus maritimus). The aim of the study was to investigate the effects of age, condition, location and reproductive status on steroid profile in female polar...... bears. Levels of pregnenolone (PRE), progesterone, androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone, dihydrotestosterone, estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in blood (serum) of free-living female polar bears (n = 15) from Svalbard, Norway, by gas...

  18. Steroid hormone profile in female polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Gustavson, Lisa; Jenssen, Bjørn Munro; Bytingsvik, Jenny

    2015-01-01

    The polar bear is an iconic Arctic species, threatened by anthropogenic impacts such as pollution and climate change. Successful reproduction of polar bears depends on a functioning steroid hormone system, which is susceptible to effects of persistent organic pollutants. The present study...... is the first study to report circulating concentrations of nine steroid hormones (i.e., estrogens, androgens and progestagens) in female polar bears (Ursus maritimus). The aim of the study was to investigate the effects of age, condition, location and reproductive status on steroid profile in female polar...... bears. Levels of pregnenolone (PRE), progesterone, androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone, dihydrotestosterone, estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in blood (serum) of free-living female polar bears (n = 15) from Svalbard, Norway, by gas...

  19. Polar Bears from Space: Assessing Satellite Imagery as a Tool to Track Arctic Wildlife

    OpenAIRE

    Stapleton, Seth; LaRue, Michelle; Lecomte, Nicolas; Atkinson, Stephen; Garshelis, David; Porter, Claire; Atwood, Todd

    2014-01-01

    Development of efficient techniques for monitoring wildlife is a priority in the Arctic, where the impacts of climate change are acute and remoteness and logistical constraints hinder access. We evaluated high resolution satellite imagery as a tool to track the distribution and abundance of polar bears. We examined satellite images of a small island in Foxe Basin, Canada, occupied by a high density of bears during the summer ice-free season. Bears were distinguished from other light-colored s...

  20. East Greenland and Barents Sea polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Pertoldi, Cino; Sonne, Christian; Wiig, Øystein

    2012-01-01

    A morphometric study was conducted on four skull traits of 37 male and 18 female adult East Greenland polar bears (Ursus maritimus) collected 18921968, and on 54 male and 44 female adult Barents Sea polar bears collected 19501969. The aim was to compare differences in size and shape of the bear...... and three clusters for Barents Sea females. East Greenland consisted of one female and one male cluster. A principal component analysis (PCA) conducted on the clusters defined by the mixture analysis, showed that East Greenland and Barents Sea polar bear populations overlapped to a large degree, especially...... and genetic factors seem to have contributed to the observed skull differences between the two populations. Overall, results indicate that many Barents Sea polar bears are morphometrically similar to the East Greenland ones, suggesting an exchange of individuals between the two populations. Furthermore...

  1. Human disturbances of denning polar bears in Alaska

    Energy Technology Data Exchange (ETDEWEB)

    Amstrup, S.C. (Alaska Fish and Wildlife Research Center, Anchorage, AK (United States))

    1993-09-01

    Polar bears (Ursus maritimus) give birth in dens of snow and ice. The altricial neonates cannot leave the den for >2 months post-partum and are potentially vulnerable to disturbances near dens. The coastal plain (1002) area of Alaska's Arctic National Wildlife Refuge (ANWR) lies in a region of known polar bear denning and also may contain >9 billion barrels of recoverable oil. Polar bears in dens could be affected in many ways by hydrocarbon development. The distribution of dens on ANWR was documented between 1981 and 1992 and responses of bears in dens to various anthropogenic disturbances were observed. Of 44 dens located by radiotelemetry on the mainland coast of Alaska and Canada, 20 (45%) were on ANWR and 15 (34%) were within the 1002 area. Thus, development of ANWR will increase the potential that denning polar bears are disturbed by human activities. However, perturbations resulting from capture, marking, and radiotracking maternal bears did not affect litter sizes or stature of cubs produced. Likewise, 10 of 12 denned polar bears tolerated exposure to exceptional levels of activity. This tolerance and the fact that investment in the denning effort increases through the winter indicated that spatial and temporal restrictions on developments could prevent the potential for many disruptions of denned bears from being realized. 16 refs., 1 fig., 2 tabs.

  2. Biomechanical consequences of rapid evolution in the polar bear lineage.

    Directory of Open Access Journals (Sweden)

    Graham J Slater

    2010-11-01

    Full Text Available The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we used phylogenetic tests to estimate the rate of morphological specialization in polar bears. We then used finite element analysis (FEA to compare the limits of feeding performance in the polar bear skull to that of the phylogenetically and geographically close brown bear. Results indicate that extremely rapid evolution of semi-aquatic adaptations and dietary specialization in the polar bear lineage produced a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Our results suggest that continuation of current climate trends could affect polar bears by not only eliminating their primary food source, but also through competition with northward advancing, generalized brown populations for resources that they are ill-equipped to utilize.

  3. Biomechanical consequences of rapid evolution in the polar bear lineage.

    Science.gov (United States)

    Slater, Graham J; Figueirido, Borja; Louis, Leeann; Yang, Paul; Van Valkenburgh, Blaire

    2010-11-05

    The polar bear is the only living ursid with a fully carnivorous diet. Despite a number of well-documented craniodental adaptations for a diet of seal flesh and blubber, molecular and paleontological data indicate that this morphologically distinct species evolved less than a million years ago from the omnivorous brown bear. To better understand the evolution of this dietary specialization, we used phylogenetic tests to estimate the rate of morphological specialization in polar bears. We then used finite element analysis (FEA) to compare the limits of feeding performance in the polar bear skull to that of the phylogenetically and geographically close brown bear. Results indicate that extremely rapid evolution of semi-aquatic adaptations and dietary specialization in the polar bear lineage produced a cranial morphology that is weaker than that of brown bears and less suited to processing tough omnivorous or herbivorous diets. Our results suggest that continuation of current climate trends could affect polar bears by not only eliminating their primary food source, but also through competition with northward advancing, generalized brown populations for resources that they are ill-equipped to utilize.

  4. Human disturbances of denning polar bears in Alaska

    International Nuclear Information System (INIS)

    Amstrup, S.C.

    1993-01-01

    Polar bears (Ursus maritimus) give birth in dens of snow and ice. The altricial neonates cannot leave the den for >2 months post-partum and are potentially vulnerable to disturbances near dens. The coastal plain (1002) area of Alaska's Arctic National Wildlife Refuge (ANWR) lies in a region of known polar bear denning and also may contain >9 billion barrels of recoverable oil. Polar bears in dens could be affected in many ways by hydrocarbon development. The distribution of dens on ANWR was documented between 1981 and 1992 and responses of bears in dens to various anthropogenic disturbances were observed. Of 44 dens located by radiotelemetry on the mainland coast of Alaska and Canada, 20 (45%) were on ANWR and 15 (34%) were within the 1002 area. Thus, development of ANWR will increase the potential that denning polar bears are disturbed by human activities. However, perturbations resulting from capture, marking, and radiotracking maternal bears did not affect litter sizes or stature of cubs produced. Likewise, 10 of 12 denned polar bears tolerated exposure to exceptional levels of activity. This tolerance and the fact that investment in the denning effort increases through the winter indicated that spatial and temporal restrictions on developments could prevent the potential for many disruptions of denned bears from being realized. 16 refs., 1 fig., 2 tabs

  5. Population ecology of polar bears in Davis Strait, Canada and Greenland

    Science.gov (United States)

    Peacock, Elizabeth; Taylor, Mitchell K.; Laake, Jeffrey L.; Stirling, Ian

    2013-01-01

    Until recently, the sea ice habitat of polar bears was understood to be variable, but environmental variability was considered to be cyclic or random, rather than progressive. Harvested populations were believed to be at levels where density effects were considered not significant. However, because we now understand that polar bear demography can also be influenced by progressive change in the environment, and some populations have increased to greater densities than historically lower numbers, a broader suite of factors should be considered in demographic studies and management. We analyzed 35 years of capture and harvest data from the polar bear (Ursus maritimus) subpopulation in Davis Strait, including data from a new study (2005–2007), to quantify its current demography. We estimated the population size in 2007 to be 2,158 ± 180 (SE), a likely increase from the 1970s. We detected variation in survival, reproductive rates, and age-structure of polar bears from geographic sub-regions. Survival and reproduction of bears in southern Davis Strait was greater than in the north and tied to a concurrent dramatic increase in breeding harp seals (Pagophilus groenlandicus) in Labrador. The most supported survival models contained geographic and temporal variables. Harp seal abundance was significantly related to polar bear survival. Our estimates of declining harvest recovery rate, and increasing total survival, suggest that the rate of harvest declined over time. Low recruitment rates, average adult survival rates, and high population density, in an environment of high prey density, but deteriorating and variable ice conditions, currently characterize the Davis Strait polar bears. Low reproductive rates may reflect negative effects of greater densities or worsening ice conditions.

  6. Acquired umbilical hernias in four captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Velguth, Karen E; Rochat, Mark C; Langan, Jennifer N; Backues, Kay

    2009-12-01

    Umbilical hernias are a common occurrence in domestic animals and humans but have not been well documented in polar bears. Surgical reduction and herniorrhaphies were performed to correct acquired hernias in the region of the umbilicus in four adult captive polar bears (Ursus maritimus) housed in North American zoos. Two of the four bears were clinically unaffected by their hernias prior to surgery. One bear showed signs of severe discomfort following acute enlargement of the hernia. In another bear, re-herniation led to acute abdominal pain due to gastric entrapment and strangulation. The hernias in three bears were surgically repaired by debridement of the hernia ring and direct apposition of the abdominal wall, while the large defect in the most severely affected bear was closed using polypropylene mesh to prevent excessive tension. The cases in this series demonstrate that while small hernias may remain clinically inconsequential for long periods of time, enlargement or recurrence of the defect can lead to incarceration and acute abdominal crisis. Umbilical herniation has not been reported in free-ranging polar bears, and it is suspected that factors such as body condition, limited exercise, or enclosure design potentially contribute to the development of umbilical hernias in captive polar bears.

  7. Genomic evidence of widespread admixture from polar bears into brown bears during the last ice age.

    Science.gov (United States)

    Cahill, James A; Heintzman, Peter D; Harris, Kelley; Teasdale, Matthew D; Kapp, Joshua; Soares, André E Rodrigues; Stirling, Ian; Bradley, Daniel; Edwards, Ceiridwen J; Graim, Kiley; Kisleika, Aliaksandr A; Malev, Alexander V; Monaghan, Nigel; Green, Richard E; Shapiro, Beth

    2018-02-20

    Recent genomic analyses have provided substantial evidence for past periods of gene flow from polar bears (Ursus maritimus) into Alaskan brown bears (Ursus arctos), with some analyses suggesting a link between climate change and genomic introgression. However, because it has mainly been possible to sample bears from the present day, the timing, frequency, and evolutionary significance of this admixture remains unknown. Here, we analyze genomic DNA from three additional and geographically distinct brown bear populations, including two that lived temporally close to the peak of the last ice age. We find evidence of admixture in all three populations, suggesting that admixture between these species has been common in their recent evolutionary history. In addition, analyses of ten fossil bears from the now-extinct Irish population indicate that admixture peaked during the last ice age, when brown bear and polar bear ranges overlapped. Following this peak, the proportion of polar bear ancestry in Irish brown bears declined rapidly until their extinction. Our results support a model in which ice age climate change created geographically widespread conditions conducive to admixture between polar bears and brown bears, as is again occurring today. We postulate that this model will be informative for many admixing species pairs impacted by climate change. Our results highlight the power of paleogenomics to reveal patterns of evolutionary change that are otherwise masked in contemporary data.

  8. Testing methods for using high-resolution satellite imagery to monitor polar bear abundance and distribution

    Science.gov (United States)

    LaRue, Michelle A.; Stapleton, Seth P.; Porter, Claire; Atkinson, Stephen N.; Atwood, Todd C.; Dyck, Markus; Lecomte, Nicolas

    2015-01-01

    High-resolution satellite imagery is a promising tool for providing coarse information about polar species abundance and distribution, but current applications are limited. With polar bears (Ursus maritimus), the technique has only proven effective on landscapes with little topographic relief that are devoid of snow and ice, and time-consuming manual review of imagery is required to identify bears. Here, we evaluated mechanisms to further develop methods for satellite imagery by examining data from Rowley Island, Canada. We attempted to automate and expedite detection via a supervised spectral classification and image differencing to expedite image review. We also assessed what proportion of a region should be sampled to obtain reliable estimates of density and abundance. Although the spectral signature of polar bears differed from nontarget objects, these differences were insufficient to yield useful results via a supervised classification process. Conversely, automated image differencing—or subtracting one image from another—correctly identified nearly 90% of polar bear locations. This technique, however, also yielded false positives, suggesting that manual review will still be required to confirm polar bear locations. On Rowley Island, bear distribution approximated a Poisson distribution across a range of plot sizes, and resampling suggests that sampling >50% of the site facilitates reliable estimation of density (CV in certain areas, but large-scale applications remain limited because of the challenges in automation and the limited environments in which the method can be effectively applied. Improvements in resolution may expand opportunities for its future uses.

  9. Genetic relationships of extant brown bears (Ursus arctos) and polar bears (Ursus maritimus).

    Science.gov (United States)

    Cronin, Matthew A; MacNeil, Michael D

    2012-01-01

    Polar bears (Ursus maritimus) and brown bears (Ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic comparisons have been made. We used previously published genotype data for 8 microsatellite DNA loci from 930 brown bears in 19 populations and 473 polar bears in 16 populations to compare the population genetic relationships of extant populations of the species. Genetic distances (Nei standard distance = 1.157), the proportion of private alleles (52% of alleles are not shared by the species), and Bayesian cluster analysis are consistent with morphological and life-history characteristics that distinguish polar bears and brown bears as different species with little or no gene flow among extant populations.

  10. Polar bear maternity denning in the Beaufort Sea

    Science.gov (United States)

    Amstrup, Steven C.; Gardner, Craig L.

    1994-01-01

    The distribution of polar bears (Ursus maritimus) is circumpolar in the NOrthern Hemisphere, but known locations of maternal dens are concentrated in relatively few, widely scattered locations. Denning is either uncommon or unknown within gaps. To understand effects of industrial development and propose increases in hunting, the temporal and spatial distribution of denning in the Beaufort Sea must be known. We caputred and radiocollared polar bears between 1981 and 1991 and determined tht denning in the Beaufort Sea region was sufficient to account for the estimated population there. Of 90 dend, 48 were on drifting pack ice, 38 on land, and 4 on land-fast ice. The portions of dens on land was higher (P= 0.029) in later compared with earlier years of the study. Bears denning on pack ice drifting as far as 997 km (x=385km) while in dens. there was no difference in cun production by bears denning on land and pack ice (P =0.66). Mean entry and exit dates were 11 November and 5 April for land dens and 22 November and 26 March for pack-ice dens. Female polar bears captured in the Beaufort Sea appeared to be isolated from those caught eat of Cape Bathurst in Canada. Of 35 polar bears that denned along the mainland coast of Alaska and Canada 80% denned between 137 00'W snf 146 59'W. Bears followed to >1 den did not reuse sites and consecutive dens were 20-1,304 km apart. However radio-collared bears are largely faithful to substrate (pack-ice, land, and land-fast ice) and the general geographic area of previous dens. Bears denning on land may be vunerable to human activities such as hunting and industrial development. However, predictable denning chronology and alck of site fidelity indicate that many potential impacts on denning polar bears could be mitigated.

  11. Predicting 21st-century polar bear habitat distribution from global climate models

    Science.gov (United States)

    Durner, G.M.; Douglas, D.C.; Nielson, R.M.; Amstrup, Steven C.; McDonald, T.L.; Stirling, I.; Mauritzen, Mette; Born, E.W.; Wiig, O.; Deweaver, E.; Serreze, Mark C.; Belikov, Stanislav; Holland, M.M.; Maslanik, J.; Aars, Jon; Bailey, D.A.; Derocher, A.E.

    2009-01-01

    Projections of polar bear (Ursus maritimus) sea ice habitat distribution in the polar basin during the 21st century were developed to understand the consequences of anticipated sea ice reductions on polar bear populations. We used location data from satellitecollared polar bears and environmental data (e.g., bathymetry, distance to coastlines, and sea ice) collected from 1985 to 1995 to build resource selection functions (RSFs). RSFs described habitats that polar bears preferred in summer, autumn, winter, and spring. When applied to independent data from 1996 to 2006, the RSFs consistently identified habitats most frequently used by polar bears. We applied the RSFs to monthly maps of 21st-century sea ice concentration projected by 10 general circulation models (GCMs) used in the Intergovernmental Panel of Climate Change Fourth Assessment Report, under the A1B greenhouse gas forcing scenario. Despite variation in their projections, all GCMs indicated habitat losses in the polar basin during the 21st century. Losses in the highest-valued RSF habitat (optimal habitat) were greatest in the southern seas of the polar basin, especially the Chukchi and Barents seas, and least along the Arctic Ocean shores of Banks Island to northern Greenland. Mean loss of optimal polar bear habitat was greatest during summer; from an observed 1.0 million km2 in 1985-1995 (baseline) to a projected multi-model mean of 0.32 million km2 in 2090-2099 (-68% change). Projected winter losses of polar bear habitat were less: from 1.7 million km2 in 1985-1995 to 1.4 million km2 in 2090-2099 (-17% change). Habitat losses based on GCM multi-model means may be conservative; simulated rates of habitat loss during 1985-2006 from many GCMs were less than the actual observed rates of loss. Although a reduction in the total amount of optimal habitat will likely reduce polar bear populations, exact relationships between habitat losses and population demographics remain unknown. Density and energetic

  12. Dietary biomagnification of organochlorine contaminants in Alaskan polar bears

    Science.gov (United States)

    Bentzen, T.W.; Follmann, Erich H.; Amstrup, Steven C.; York, G.S.; Wooller, M.J.; Muir, D.C.G.; O'Hara, T. M.

    2008-01-01

    Concentrations of organochlorine contaminants in the adipose tissue of polar bears (Ursus maritimus Phipps, 1774) vary throughout the Arctic. The range in concentrations has not been explained fully by bear age, sex, condition, location, or reproductive status. Dietary pathways expose polar bears to a variety of contaminant profiles and concentrations. Prey range from lower trophic level bowhead whales (Balaena mysticetus L., 1758), one of the least contaminated marine mammals, to highly contaminated upper trophic level ringed seals (Phoca hispida (Schreber, 1775)). We used ??15N and ??13C signatures to estimate the trophic status of 42 polar bears sampled along Alaska's Beaufort Sea coast to determine the relationship between organochlorine concentration and trophic level. The ?? 15N values in the cellular portions of blood ranged from 18.2% to 20.7%. We found strong positive relationships between concentrations of the most recalcitrant polychlorinated biphenyls (PCBs) and ??15N values in models incorporating age, lipid content, and ??13C value. Specifically these models accounted for 67% and 76% of the variation in PCB153 and oxychlordane concentration in male polar bears and 85% and 93% in females, respectively. These results are strong indicators of variation in diet and biomagnification of organochlorines among polar bears related to their sex, age, and trophic position. ?? 2008 NRC.

  13. Omental torsion in a captive polar bear (Ursus maritimus).

    Science.gov (United States)

    Mendez-Angulo, Jose L; Funes, Francisco J; Trent, Ava M; Willette, Michelle; Woodhouse, Kerry; Renier, Anna C

    2014-03-01

    This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2-day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen.

  14. Polar bear Ursus maritimus hearing measured with auditory evoked potentials.

    Science.gov (United States)

    Nachtigall, Paul E; Supin, Alexander Y; Amundin, Mats; Röken, Bengt; Møller, Thorsten; Mooney, T Aran; Taylor, Kristen A; Yuen, Michelle

    2007-04-01

    While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.

  15. Organohalogen concentrations and a gross and histologic assessment of multiple organ systems in East Greenland polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Sonne, C.

    To investigate the relation between biological parameters, not earlier investigated in the polar bear, and organohalogen pollution in East Greenland polar bears, we initiated a sampling of adipose tissue, internal organs and skulls from more than 100 free-ranging polar bears killed by local...... in the adipose tissue and pathological changes in skulls and internal organs. Our results suggested a decrease in adipose tissue concentrations of organohalogens in East Greenland polar bears from 1990 to 1999-2001. Two of the biological effect parameters (FA and enlarged clitoris) did not indicate a link......, infectious agents, season and meaby chronic exposure to organohalogens. These result fill out an existing knowledge gap in potential effects of environmental, organic contaminants on fluctuating asymmetry, bone mineral density and functional anatomy (histology) in the polar bear. In addition, the results may...

  16. Is bone mineral composition disrupted by organochlorines in east Greenland polar bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Born, Erik W

    2004-01-01

    We analyzed bone mineral density (BMD) in skulls of polar bears (Ursus maritimus) (n = 139) from East Greenland sampled during 1892-2002. Our primary goal was to detect possible changes in bone mineral content (osteopenia) due to elevated exposure to organochlorine [polychlorinated biphenyls (PCBs...

  17. Lumbar laminectomy in a captive, adult polar bear (Ursus maritimus).

    Science.gov (United States)

    Morrison, John F; Vakharia, Kunal; Moreland, Douglas B

    2017-01-01

    Animals held in captivity tend to live longer than do their wild counterparts, and as such, are prone to developing age-related degenerative injuries. Here, we present a case of an adult female polar bear with symptomatic lumbar stenosis. There is a paucity of literature on large mammalian spine surgery, and anatomical differences between humans and other vertebrates must be taken into consideration. A 24-year-old female polar bear residing at the zoo was found to have decreased motor function in her hind legs. Diagnostic myelography performed at the L7/S1 level demonstrated lumbar stenosis at L5/6 for which a laminectomy was performed. Postoperatively, she returned to premorbid functional level, with no apparent associated adverse sequelae. To our knowledge, this is the first reported case of spine surgery in a polar bear and demonstrates that neurosurgical diagnostic and operative techniques developed for humans can also be applied to large mammals with successful results.

  18. Remote biopsy darting and marking of polar bears

    Science.gov (United States)

    Pagano, Anthony M.; Peacock, Elizabeth; McKinney, Melissa A.

    2014-01-01

    Remote biopsy darting of polar bears (Ursus maritimus) is less invasive and time intensive than physical capture and is therefore useful when capture is challenging or unsafe. We worked with two manufacturers to develop a combination biopsy and marking dart for use on polar bears. We had an 80% success rate of collecting a tissue sample with a single biopsy dart and collected tissue samples from 143 polar bears on land, in water, and on sea ice. Dye marks ensured that 96% of the bears were not resampled during the same sampling period, and we recovered 96% of the darts fired. Biopsy heads with 5 mm diameters collected an average of 0.12 g of fur, tissue, and subcutaneous adipose tissue, while biopsy heads with 7 mm diameters collected an average of 0.32 g. Tissue samples were 99.3% successful (142 of 143 samples) in providing a genetic and sex identification of individuals. We had a 64% success rate collecting adipose tissue and we successfully examined fatty acid signatures in all adipose samples. Adipose lipid content values were lower compared to values from immobilized or harvested polar bears, indicating that our method was not suitable for quantifying adipose lipid content.

  19. Population genomics reveal recent speciation and rapid evolutionary adaptation in polar bears.

    Science.gov (United States)

    Liu, Shiping; Lorenzen, Eline D; Fumagalli, Matteo; Li, Bo; Harris, Kelley; Xiong, Zijun; Zhou, Long; Korneliussen, Thorfinn Sand; Somel, Mehmet; Babbitt, Courtney; Wray, Greg; Li, Jianwen; He, Weiming; Wang, Zhuo; Fu, Wenjing; Xiang, Xueyan; Morgan, Claire C; Doherty, Aoife; O'Connell, Mary J; McInerney, James O; Born, Erik W; Dalén, Love; Dietz, Rune; Orlando, Ludovic; Sonne, Christian; Zhang, Guojie; Nielsen, Rasmus; Willerslev, Eske; Wang, Jun

    2014-05-08

    Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyper-lipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479-343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization of the cardiovascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk of heart disease in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. A tale of two polar bear populations: Ice habitat, harvest, and body condition

    Science.gov (United States)

    Rode, K.D.; Peacock, E.; Taylor, M.; Stirling, I.; Born, E.W.; Laidre, K.L.; Wiig, O.

    2012-01-01

    One of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977-1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition. ?? 2011 The Society of Population Ecology and Springer.

  1. Organophosphate esters in East Greenland polar bears and ringed seals

    DEFF Research Database (Denmark)

    Strobel, Adelle; Willmore, William G; Sonne, Christian

    2018-01-01

    influenced by biotransformation. In the present study, the hepatic in vitro metabolism of six environmentally relevant organophosphate (OP) triesters and corresponding OP diester formation were investigated in East Greenland polar bears (PBs) and ringed seals (RSs). The in vitro metabolism assay results were...

  2. Cortisol levels in hair of East Greenland polar bears.

    Science.gov (United States)

    Bechshøft, T Ø; Sonne, C; Dietz, R; Born, E W; Novak, M A; Henchey, E; Meyer, J S

    2011-01-15

    To demonstrate the ability to assess long-term hypothalamic-pituitary-adrenocortical (HPA) axis activity in polar bears (Ursus maritimus), a pilot study was conducted in which cortisol concentrations was analyzed in hair from 7 female (3-19 years) and 10 male (6-19 years) East Greenland polar bears sampled in 1994-2006. The hair was chosen as matrix as it is non-invasive, seasonally harmonized, and has been validated as an index of long-term changes in cortisol levels. The samples were categorized according to contamination: eight were clean (2 females, 6 males), 5 had been contaminated with bear blood (2 F, 3 M), and 4 with bear fat (3 F, 1 M). There was no significant difference in cortisol concentration between the three categories after external contamination was removed. However, contaminated hair samples should be cleaned before cortisol determination. Average hair cortisol concentration was 8.90 pg/mg (range: 5.5 to 16.4 pg/mg). There was no significant correlation between cortisol concentration and age (p=0.81) or sampling year (p=0.11). However, females had higher mean cortisol concentration than males (females mean: 11.0 pg/mg, males: 7.3 pg/mg; p=0.01). The study showed that polar bear hair contains measurable amounts of cortisol and that cortisol in hair may be used in studies of long-term stress in polar bears. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Molecular phylogeny and SNP variation of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) derived from genome sequences.

    Science.gov (United States)

    Cronin, Matthew A; Rincon, Gonzalo; Meredith, Robert W; MacNeil, Michael D; Islas-Trejo, Alma; Cánovas, Angela; Medrano, Juan F

    2014-01-01

    We assessed the relationships of polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus) with high throughput genomic sequencing data with an average coverage of 25× for each species. A total of 1.4 billion 100-bp paired-end reads were assembled using the polar bear and annotated giant panda (Ailuropoda melanoleuca) genome sequences as references. We identified 13.8 million single nucleotide polymorphisms (SNP) in the 3 species aligned to the polar bear genome. These data indicate that polar bears and brown bears share more SNP with each other than either does with black bears. Concatenation and coalescence-based analysis of consensus sequences of approximately 1 million base pairs of ultraconserved elements in the nuclear genome resulted in a phylogeny with black bears as the sister group to brown and polar bears, and all brown bears are in a separate clade from polar bears. Genotypes for 162 SNP loci of 336 bears from Alaska and Montana showed that the species are genetically differentiated and there is geographic population structure of brown and black bears but not polar bears.

  4. Genomic evidence for island population conversion resolves conflicting theories of polar bear evolution.

    Directory of Open Access Journals (Sweden)

    James A Cahill

    Full Text Available Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus and brown bears (U. arctos remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus, plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed <1% of the autosomal genome of the ABC Islands brown bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize.

  5. Genomic evidence for island population conversion resolves conflicting theories of polar bear evolution.

    Science.gov (United States)

    Cahill, James A; Green, Richard E; Fulton, Tara L; Stiller, Mathias; Jay, Flora; Ovsyanikov, Nikita; Salamzade, Rauf; St John, John; Stirling, Ian; Slatkin, Montgomery; Shapiro, Beth

    2013-01-01

    Despite extensive genetic analysis, the evolutionary relationship between polar bears (Ursus maritimus) and brown bears (U. arctos) remains unclear. The two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. At the center of this controversy are the Alaskan ABC Islands brown bears that show evidence of shared ancestry with polar bears. We present an analysis of genome-wide sequence data for seven polar bears, one ABC Islands brown bear, one mainland Alaskan brown bear, and a black bear (U. americanus), plus recently published datasets from other bears. Surprisingly, we find clear evidence for gene flow from polar bears into ABC Islands brown bears but no evidence of gene flow from brown bears into polar bears. Importantly, while polar bears contributed bear, they contributed 6.5% of the X chromosome. The magnitude of sex-biased polar bear ancestry and the clear direction of gene flow suggest a model wherein the enigmatic ABC Island brown bears are the descendants of a polar bear population that was gradually converted into brown bears via male-dominated brown bear admixture. We present a model that reconciles heretofore conflicting genetic observations. We posit that the enigmatic ABC Islands brown bears derive from a population of polar bears likely stranded by the receding ice at the end of the last glacial period. Since then, male brown bear migration onto the island has gradually converted these bears into an admixed population whose phenotype and genotype are principally brown bear, except at mtDNA and X-linked loci. This process of genome erosion and conversion may be a common outcome when climate change or other forces cause a population to become isolated and then overrun by species with which it can hybridize.

  6. An experimental investigation of chemical communication in the polar bear

    Science.gov (United States)

    Owen, Megan A.; Swaisgood, Ronald R.; Slocomb, C.; Amstrup, Steven C.; Durner, George M.; Simac, Kristin S.; Pessier, Allan P.

    2015-01-01

    The polar bear (Ursus maritimus), with its wide-ranging movements, solitary existence and seasonal reproduction, is expected to favor chemosignaling over other communication modalities. However, the topography of its Arctic sea ice habitat is generally lacking in stationary vertical substrates routinely used for targeted scent marking in other bears. These environmental constraints may have shaped a marking strategy, unique to polar bears, for widely dispersed continuous dissemination of scent via foot pads. To investigate the role of chemical communication, pedal scents were collected from free-ranging polar bears of different sex and reproductive classes captured on spring sea ice in the Beaufort and Chukchi seas, and presented in a controlled fashion to 26 bears in zoos. Results from behavioral bioassays indicated that bears, especially females, were more likely to approach conspecific scent during the spring than the fall. Male flehmen behavior, indicative of chemosignal delivery to the vomeronasal organ, differentiated scent donor by sex and reproductive condition. Histologic examination of pedal skin collected from two females indicated prominent and profuse apocrine glands in association with large compound hair follicles, suggesting that they may produce scents that function as chemosignals. These results suggest that pedal scent, regardless of origin, conveys information to conspecifics that may facilitate social and reproductive behavior, and that chemical communication in this species has been adaptively shaped by environmental constraints of its habitat. However, continuously distributed scent signals necessary for breeding behavior may prove less effective if current and future environmental conditions cause disruption of scent trails due to increased fracturing of sea ice.

  7. Lactational transfer of mercury and polychlorinated biphenyls in polar bears.

    Science.gov (United States)

    Knott, Katrina K; Boyd, Daryle; Ylitalo, Gina M; O'Hara, Todd M

    2012-07-01

    We examined concentrations of total mercury (tHg, inorganic and methylated forms) and polychlorinated biphenyls (PCBs) in blood and milk from free-ranging Southern Beaufort-Chukchi Sea polar bears (Ursus maritimus) to assess maternal transfer of contaminants during lactation and the potential health risk to nursing young. Concentrations of contaminants in the blood of dependent and juvenile animals (ages 1-5 years) ranged from 35.9 to 52.2 μg kg(-1) ww for tHg and 13.9 to 52.2 μg kg(-1) ww (3255.81-11067.79 μg kg(-1) lw) for ΣPCB(7)s, similar to those of adult females, but greater than adult males. Contaminant concentrations in milk ranged from 5.7 to 71.8 μg tHg kg(-1)ww and 160 to 690 μg ΣPCB(11)s kg(-1) ww (547-5190 μg kg(-1) lw). The daily intake levels for tHg by milk consumption estimated for dependent young were below the tolerable daily intake level (TDIL) of tHg established for adult humans. Although the daily intake levels of PCBs through milk consumption for cubs of the year exceeded the TDIL thresholds, calculated dioxin equivalents for PCBs in milk were below adverse physiological thresholds for aquatic mammals. Relatively high concentrations of non-dioxin like PCBs in polar bear milk and blood could impact endocrine function of Southern Beaufort-Chukchi Sea polar bears, but this is uncertain. Transfer of contaminants during mid to late lactation likely limits bioaccumulation of dietary contaminants in female polar bears during spring. As polar bears respond to changes in their arctic sea ice habitat, the adverse health impacts associated with nutritional stress may be exacerbated by tHg and PCBs exposure, especially in ecologically and toxicologically sensitive polar bear cohorts such as reproductive females and young. Copyright © 2012. Published by Elsevier Ltd.

  8. Habitat degradation affects the summer activity of polar bears.

    Science.gov (United States)

    Ware, Jasmine V; Rode, Karyn D; Bromaghin, Jeffrey F; Douglas, David C; Wilson, Ryan R; Regehr, Eric V; Amstrup, Steven C; Durner, George M; Pagano, Anthony M; Olson, Jay; Robbins, Charles T; Jansen, Heiko T

    2017-05-01

    Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species' distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two adjacent subpopulations to changes in habitat availability during the annual sea ice minimum using activity data. Location and activity sensor data collected from 1989 to 2014 for 202 adult female polar bears in the Southern Beaufort Sea (SB) and Chukchi Sea (CS) subpopulations were used to compare activity in three habitat types varying in prey availability: (1) land; (2) ice over shallow, biologically productive waters; and (3) ice over deeper, less productive waters. Bears varied activity across and within habitats with the highest activity at 50-75% sea ice concentration over shallow waters. On land, SB bears exhibited variable but relatively high activity associated with the use of subsistence-harvested bowhead whale carcasses, whereas CS bears exhibited low activity consistent with minimal feeding. Both subpopulations had fewer observations in their preferred shallow-water sea ice habitats in recent years, corresponding with declines in availability of this substrate. The substantially higher use of marginal habitats by SB bears is an additional mechanism potentially explaining why this subpopulation has experienced negative effects of sea ice loss compared to the still-productive CS subpopulation. Variability in activity among, and within, habitats suggests that bears alter their behavior in response to habitat conditions, presumably in an attempt to balance prey availability with energy costs.

  9. 50 CFR 18.30 - Polar bear sport-hunted trophy import permits.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 6 2010-10-01 2010-10-01 false Polar bear sport-hunted trophy import... IMPORTATION OF WILDLIFE AND PLANTS (CONTINUED) MARINE MAMMALS Special Exceptions § 18.30 Polar bear sport... estate, must submit an application for a permit to import a trophy of a polar bear taken in Canada to the...

  10. 77 FR 23432 - Endangered and Threatened Wildlife and Plants; Special Rule for the Polar Bear

    Science.gov (United States)

    2012-04-19

    ... Polar Bear AGENCY: Fish and Wildlife Service, Interior. ACTION: Proposed rule; availability of draft... and advisable to provide for the conservation of the polar bear (Ursus maritimus). The Secretary has the discretion to prohibit by regulation with respect to the polar bear any act prohibited by section...

  11. One-dimensional heat conduction equation of the polar bear hair

    Directory of Open Access Journals (Sweden)

    Zhu Wei-Hong

    2015-01-01

    Full Text Available Hairs of a polar bear (Ursus maritimus possess special membrane-pore structure. The structure enables the polar bear to survive in the harsh Arctic regions. In this paper, the membrane-pore structure be approximately considered as fractal space, 1-D heat conduction equation of the polar bear hair is established and the solution of the equation is obtained.

  12. Fractional model for heat conduction in polar bear hairs

    Directory of Open Access Journals (Sweden)

    Wang Qing-Li

    2012-01-01

    Full Text Available Time-fractional differential equations can accurately describe heat conduction in fractal media, such as wool fibers, goose down and polar bear hair. The fractional complex transform is used to convert time-fractional heat conduction equations with the modified Riemann-Liouville derivative into ordinary differential equations, and exact solutions can be easily obtained. The solution process is straightforward and concise.

  13. Polar Bears Exhibit Genome-Wide Signatures of Bioenergetic Adaptation to Life in the Arctic Environment

    OpenAIRE

    Welch, Andreanna J.; Bedoya-Reina, Oscar C.; Carretero-Paulet, Lorenzo; Miller, Webb; Rode, Karyn D.; Lindqvist, Charlotte

    2014-01-01

    Polar bears (Ursus maritimus) face extremely cold temperatures and periods of fasting, which might result in more severe energetic challenges than those experienced by their sister species, the brown bear (U. arctos). We have examined the mitochondrial and nuclear genomes of polar and brown bears to investigate whether polar bears demonstrate lineage-specific signals of molecular adaptation in genes associated with cellular respiration/energy production. We observed increased evolutionary rat...

  14. Polar bear hepatic cytochrome P450: Immunochemical quantitation, EROD/PROD activity and organochlorines

    Energy Technology Data Exchange (ETDEWEB)

    Letcher, R.J.; Norstrom, R.J. [Carleton Univ., Ottawa, Ontario (Canada). Centre for Analytical and Environmental Chemistry]|[Environment Canada, Ottawa, Ontario (Canada). Canadian Wildlife Service

    1994-12-31

    Polar bears (Ursus maritimus) are an ubiquitous mammal atop the arctic marine food chain and bioaccumulate lipophilic environmental contaminants. Antibodies prepared against purified rat liver cytochrome P450-1 Al, -1 A2, -2Bl and -3Al enzymes have been found to cross-react with structurally-related orthologues present in the hepatic microsomes of wild polar bears, immunochemically determined levels of P450-1 A and -2B proteins in polar bear liver relative to liver of untreated rats suggested enzyme induction, probably as a result of exposure to xenobiotic contaminants. Optical density quantitation of the most immunochemically responsive isozymes P450-I Al, -IA2 and -2Bi to polygonal rabbit anti-rat P450-IA/IA2 sera and -2BI antibodies in hepatic microsomes of 13 adult male polar bars from the Resolute Bay area of the Canadian Arctic is presented. Correlations with EROD and PROD catalytic activities and levels of organochlorines, such as polychlorinated biphenyls (PCBs), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (p,p-DDE) and their methyl sulfone (MeSO2-) metabolites are made to determine if compound-specific enzyme induction linkages exist. Inter-species immunochemical quantitation of isozymic P450 cytochromes can serve as an indicator of exposure to biologically active contaminant.

  15. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, I. [Canadian Wildlife Service, Edmonton, AB (Canada); Oritsland, N.A. [Norsk Polarinstitutt, Oslo (Norway)

    1995-12-01

    Biological studies were conducted in arctic marine areas to assess the possible impacts of industrial development and to identify areas of critical habitat that might warrant some degree of protection. Ringed seals were studied since polar bears depend on them for food and both species are of cultural and economic importance to the Inuit. The number of seals needed to support a population of polar bears was estimated independently using both behavioral and energetic data. Predation and energy matrices indicated that high levels of predation on seals were sustainable only if most animals killed were young-of-the-year. Densities of seals and the productivity of bears appeared to vary in direct proportion to each other, indicating a high level of sensitivity of relationship between ringed seals and polar bears, at the population level. 86 refs., 6 tabs., 5 figs.

  16. Polar bears from space: assessing satellite imagery as a tool to track Arctic wildlife.

    Directory of Open Access Journals (Sweden)

    Seth Stapleton

    Full Text Available Development of efficient techniques for monitoring wildlife is a priority in the Arctic, where the impacts of climate change are acute and remoteness and logistical constraints hinder access. We evaluated high resolution satellite imagery as a tool to track the distribution and abundance of polar bears. We examined satellite images of a small island in Foxe Basin, Canada, occupied by a high density of bears during the summer ice-free season. Bears were distinguished from other light-colored spots by comparing images collected on different dates. A sample of ground-truthed points demonstrated that we accurately classified bears. Independent observers reviewed images and a population estimate was obtained using mark-recapture models. This estimate (N: 94; 95% Confidence Interval: 92-105 was remarkably similar to an abundance estimate derived from a line transect aerial survey conducted a few days earlier (N: 102; 95% CI: 69-152. Our findings suggest that satellite imagery is a promising tool for monitoring polar bears on land, with implications for use with other Arctic wildlife. Large scale applications may require development of automated detection processes to expedite review and analysis. Future research should assess the utility of multi-spectral imagery and examine sites with different environmental characteristics.

  17. Polar bears from space: assessing satellite imagery as a tool to track Arctic wildlife.

    Science.gov (United States)

    Stapleton, Seth; LaRue, Michelle; Lecomte, Nicolas; Atkinson, Stephen; Garshelis, David; Porter, Claire; Atwood, Todd

    2014-01-01

    Development of efficient techniques for monitoring wildlife is a priority in the Arctic, where the impacts of climate change are acute and remoteness and logistical constraints hinder access. We evaluated high resolution satellite imagery as a tool to track the distribution and abundance of polar bears. We examined satellite images of a small island in Foxe Basin, Canada, occupied by a high density of bears during the summer ice-free season. Bears were distinguished from other light-colored spots by comparing images collected on different dates. A sample of ground-truthed points demonstrated that we accurately classified bears. Independent observers reviewed images and a population estimate was obtained using mark-recapture models. This estimate (N: 94; 95% Confidence Interval: 92-105) was remarkably similar to an abundance estimate derived from a line transect aerial survey conducted a few days earlier (N: 102; 95% CI: 69-152). Our findings suggest that satellite imagery is a promising tool for monitoring polar bears on land, with implications for use with other Arctic wildlife. Large scale applications may require development of automated detection processes to expedite review and analysis. Future research should assess the utility of multi-spectral imagery and examine sites with different environmental characteristics.

  18. Serosurvey of selected zoonotic agents in polar bears (Ursus maritimus)

    Science.gov (United States)

    Rah, H.; Chomel, B.B.; Follmann, E.H.; Kasten, R.W.; Hew, C.H.; Farver, T.B.; Garner, G.W.; Amstrup, Steven C.

    2005-01-01

    Between 1982 and 1999 blood samples were collected from 500 polar bears (Ursus maritimus) captured in the Beaufort and Chukchi seas, to determine the seroprevalence of Brucella species, Toxoplasma gondii, and Trichinella species infections. The bears were classified into four age groups, cubs, yearlings, subadults and adults. Brucella and Toxoplasma antibodies were detected by agglutination (a buffered acidified card antigen and rapid automated presumptive test for brucellosis and a commercial latex agglutination test for toxoplasmosis); an ELISA was used to detect Thichinella antibodies. The overall seroprevalence of Brucella species was 5 per cent, and subadults and yearlings were 2.62 times (95 per cent confidence interval 1-02 to 6-82) more likely to be seropositive for Brucella species than adults and their cubs. The antibody prevalence for Toxoplasma gondii was 6 per cent, and for Trichinella species 55.6 per cent. The prevalence of antibodies to Trichinella species increased with age (P<0.001).

  19. Climate change threatens polar bear populations: A stochastic demographic analysis

    Science.gov (United States)

    Hunter, C.M.; Caswell, H.; Runge, M.C.; Regehr, E.V.; Amstrup, Steven C.; Stirling, I.

    2010-01-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in ?? in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log ??s, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log ??s ' - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic

  20. Climate change threatens polar bear populations: a stochastic demographic analysis.

    Science.gov (United States)

    Hunter, Christine M; Caswell, Hal; Runge, Michael C; Regehr, Eric V; Amstrup, Steve C; Stirling, Ian

    2010-10-01

    The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population

  1. Demography and population status of polar bears in western Hudson Bay

    Science.gov (United States)

    Lunn, Nicholas J.; Regher, Eric V; Servanty, Sabrina; Converse, Sarah J.; Richardson, Evan S.; Stirling, Ian

    2013-01-01

    We evaluated the demography and population status of the Western Hudson Bay (WH) polar bear subpopulation for the period 1984-2011, using live-recapture data from research studies and management actions, and dead-recovery data from polar bears harvested for subsistence purposes or removed during human-bear conflicts.

  2. A Thermally Insulating Textile Inspired by Polar Bear Hair.

    Science.gov (United States)

    Cui, Ying; Gong, Huaxin; Wang, Yujie; Li, Dewen; Bai, Hao

    2018-04-01

    Animals living in the extremely cold environment, such as polar bears, have shown amazing capability to keep warm, benefiting from their hollow hairs. Mimicking such a strategy in synthetic fibers would stimulate smart textiles for efficient personal thermal management, which plays an important role in preventing heat loss and improving efficiency in house warming energy consumption. Here, a "freeze-spinning" technique is used to realize continuous and large-scale fabrication of fibers with aligned porous structure, mimicking polar bear hairs, which is difficult to achieve by other methods. A textile woven with such biomimetic fibers shows an excellent thermal insulation property as well as good breathability and wearability. In addition to passively insulating heat loss, the textile can also function as a wearable heater, when doped with electroheating materials such as carbon nanotubes, to induce fast thermal response and uniform electroheating while maintaining its soft and porous nature for comfortable wearing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Ancestral polymorphisms and sex-biased migration shaped the demographic history of brown bears and polar bears.

    Science.gov (United States)

    Nakagome, Shigeki; Mano, Shuhei; Hasegawa, Masami

    2013-01-01

    Recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA) and matrilineal mitochondrial DNA (mtDNA). Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (aDNA) or more than 14 times (mtDNA) larger population sizes than polar bears and that polar bear lineage is derived from within brown bear diversity. In brown bears, the effective population size ratio of mtDNA to aDNA was at least 0.62, which deviated from the expected value of 0.25, suggesting matriarchal population due to female philopatry and male-biased migration. These results emphasize that ancestral polymorphisms and sex-biased migration may have contributed to conflicting branching patterns in brown and polar bears across aDNA genes and mtDNA.

  4. Ancestral polymorphisms and sex-biased migration shaped the demographic history of brown bears and polar bears.

    Directory of Open Access Journals (Sweden)

    Shigeki Nakagome

    Full Text Available Recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. Genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal DNA (aDNA and matrilineal mitochondrial DNA (mtDNA. Based on multi-locus genomic sequences from aDNA and mtDNA, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (aDNA or more than 14 times (mtDNA larger population sizes than polar bears and that polar bear lineage is derived from within brown bear diversity. In brown bears, the effective population size ratio of mtDNA to aDNA was at least 0.62, which deviated from the expected value of 0.25, suggesting matriarchal population due to female philopatry and male-biased migration. These results emphasize that ancestral polymorphisms and sex-biased migration may have contributed to conflicting branching patterns in brown and polar bears across aDNA genes and mtDNA.

  5. Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear.

    Science.gov (United States)

    Lindqvist, Charlotte; Schuster, Stephan C; Sun, Yazhou; Talbot, Sandra L; Qi, Ji; Ratan, Aakrosh; Tomsho, Lynn P; Kasson, Lindsay; Zeyl, Eve; Aars, Jon; Miller, Webb; Ingólfsson, Olafur; Bachmann, Lutz; Wiig, Oystein

    2010-03-16

    The polar bear has become the flagship species in the climate-change discussion. However, little is known about how past climate impacted its evolution and persistence, given an extremely poor fossil record. Although it is undisputed from analyses of mitochondrial (mt) DNA that polar bears constitute a lineage within the genetic diversity of brown bears, timing estimates of their divergence have differed considerably. Using next-generation sequencing technology, we have generated a complete, high-quality mt genome from a stratigraphically validated 130,000- to 110,000-year-old polar bear jawbone. In addition, six mt genomes were generated of extant polar bears from Alaska and brown bears from the Admiralty and Baranof islands of the Alexander Archipelago of southeastern Alaska and Kodiak Island. We show that the phylogenetic position of the ancient polar bear lies almost directly at the branching point between polar bears and brown bears, elucidating a unique morphologically and molecularly documented fossil link between living mammal species. Molecular dating and stable isotope analyses also show that by very early in their evolutionary history, polar bears were already inhabitants of the Artic sea ice and had adapted very rapidly to their current and unique ecology at the top of the Arctic marine food chain. As such, polar bears provide an excellent example of evolutionary opportunism within a widespread mammalian lineage.

  6. Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear

    Science.gov (United States)

    Lindqvist, Charlotte; Schuster, Stephan C.; Sun, Yazhou; Talbot, Sandra L.; Qi, Ji; Ratan, Aakrosh; Tomsho, Lynn P.; Kasson, Lindsay; Zeyl, Eve; Aars, Jon; Miller, Webb; Ingólfsson, Ólafur; Bachmann, Lutz; Wiig, Øystein

    2010-01-01

    The polar bear has become the flagship species in the climate-change discussion. However, little is known about how past climate impacted its evolution and persistence, given an extremely poor fossil record. Although it is undisputed from analyses of mitochondrial (mt) DNA that polar bears constitute a lineage within the genetic diversity of brown bears, timing estimates of their divergence have differed considerably. Using next-generation sequencing technology, we have generated a complete, high-quality mt genome from a stratigraphically validated 130,000- to 110,000-year-old polar bear jawbone. In addition, six mt genomes were generated of extant polar bears from Alaska and brown bears from the Admiralty and Baranof islands of the Alexander Archipelago of southeastern Alaska and Kodiak Island. We show that the phylogenetic position of the ancient polar bear lies almost directly at the branching point between polar bears and brown bears, elucidating a unique morphologically and molecularly documented fossil link between living mammal species. Molecular dating and stable isotope analyses also show that by very early in their evolutionary history, polar bears were already inhabitants of the Artic sea ice and had adapted very rapidly to their current and unique ecology at the top of the Arctic marine food chain. As such, polar bears provide an excellent example of evolutionary opportunism within a widespread mammalian lineage. PMID:20194737

  7. Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear

    Science.gov (United States)

    Lindqvist, Charlotte; Schuster, Stephan C.; Sun, Yazhou; Talbot, Sandra L.; Qi, Ji; Ratan, Aakrosh; Tomsho, Lynn P.; Kasson, Lindsay; Zeyl, Eve; Aars, Jon; Miller, Webb; Ingólfsson, Ólafur; Bachmann, Lutz; Wiig, Øystein

    2010-01-01

    The polar bear has become the flagship species in the climate-change discussion. However, little is known about how past climate impacted its evolution and persistence, given an extremely poor fossil record. Although it is undisputed from analyses of mitochondrial (mt) DNA that polar bears constitute a lineage within the genetic diversity of brown bears, timing estimates of their divergence have differed considerably. Using next-generation sequencing technology, we have generated a complete, high-quality mt genome from a stratigraphically validated 130,000- to 110,000-year-old polar bear jawbone. In addition, six mt genomes were generated of extant polar bears from Alaska and brown bears from the Admiralty and Baranof islands of the Alexander Archipelago of southeastern Alaska and Kodiak Island. We show that the phylogenetic position of the ancient polar bear lies almost directly at the branching point between polar bears and brown bears, elucidating a unique morphologically and molecularly documented fossil link between living mammal species. Molecular dating and stable isotope analyses also show that by very early in their evolutionary history, polar bears were already inhabitants of the Artic sea ice and had adapted very rapidly to their current and unique ecology at the top of the Arctic marine food chain. As such, polar bears provide an excellent example of evolutionary opportunism within a widespread mammalian lineage.

  8. Black bear density in Glacier National Park, Montana

    Science.gov (United States)

    Stetz, Jeff B.; Kendall, Katherine C.; Macleod, Amy C.

    2013-01-01

    We report the first abundance and density estimates for American black bears (Ursus americanus) in Glacier National Park (NP),Montana, USA.We used data from 2 independent and concurrent noninvasive genetic sampling methods—hair traps and bear rubs—collected during 2004 to generate individual black bear encounter histories for use in closed population mark–recapture models. We improved the precision of our abundance estimate by using noninvasive genetic detection events to develop individual-level covariates of sampling effort within the full and one-half mean maximum distance moved (MMDM) from each bear’s estimated activity center to explain capture probability heterogeneity and inform our estimate of the effective sampling area.Models including the one-halfMMDMcovariate received overwhelming Akaike’s Information Criterion support suggesting that buffering our study area by this distance would be more appropriate than no buffer or the full MMDM buffer for estimating the effectively sampled area and thereby density. Our modelaveraged super-population abundance estimate was 603 (95% CI¼522–684) black bears for Glacier NP. Our black bear density estimate (11.4 bears/100 km2, 95% CI¼9.9–13.0) was consistent with published estimates for populations that are sympatric with grizzly bears (U. arctos) and without access to spawning salmonids. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  9. Do organohalogen contaminants contribute to histopathology in liver from East Greenland polar bears (Ursus maritimus)?

    Science.gov (United States)

    Sonne, Christian; Dietz, Rune; Leifsson, Pall S; Born, Erik W; Letcher, Robert J; Kirkegaard, Maja; Muir, Derek C G; Riget, Frank F; Hyldstrup, Lars

    2005-11-01

    In East Greenland polar bears (Ursus maritimus), anthropogenic organohalogen compounds (OHCs) (e.g., polychlorinated biphenyls, dichlorodiphenyltrichloroethane, and polybrominated diphenyl ethers) contributed to renal lesions and are believed to reduce bone mineral density. Because OHCs are also hepatotoxic, we investigated liver histology of 32 subadult, 24 adult female, and 23 adult male East Greenland polar bears sampled during 1999-2002. Light microscopic changes consisted of nuclear displacement from the normal central cytoplasmic location in parenchymal cells, mononuclear cell infiltrations (mainly portally and as lipid granulomas), mild bile duct proliferation accompanied by fibrosis, and fat accumulation in hepatocytes and pluripotent Ito cells. Lipid accumulation in Ito cells and bile duct hyperplasia accompanied by portal fibrosis were correlated to age, whereas no changes were associated with either sex or season (summer vs. winter). For adult females, hepatocytic intracellular fat increased significantly with concentrations of the sum of hexachlorocyclohexanes, as was the case for lipid granulomas and hexachlorobenzene in adult males. Based on these relationships and the nature of the chronic inflammation, we suggest that these findings were caused by aging and long-term exposure to OHCs. Therefore, these changes may be used as biomarkers for OHC exposure in wildlife and humans. To our knowledge, this is the first time liver histology has been evaluated in relation to OHC concentrations in a mammalian wildlife species, and the information is important to future polar bear conservation strategies and health assessments of humans relying on OHC-contaminated food resources.

  10. Polarization Charge Density in Strained Graphene

    Science.gov (United States)

    Wilson, Noah

    Graphene, the world's first truly two-dimensional material, is unique for having an electronic structure described by an effective Lorentz invariant theory. One important consequence is that the ratio or Coulomb energy to kinetic energy is a constant, depending only on conditions within the lattice rather than on the average charge density as in a typical Galilean invariant material. Given this unusual property, a natural question would be how do phenomena, such as screening of a Coulomb impurity, happen in graphene? Moreover, how does the addition of uniaxial strain enhance or diminish this behavior? Here I discuss our work to calculate the charge density distribution in a lattice of strained graphene under the effect of an external Coulomb impurity. Graphene can have its band structure significantly altered by the application of uniaxial strain. Two cases are here explored: relatively weak strain at some finite chemical potential, and extreme strain with zero chemical potential. In the first system, the strain induces elliptic Dirac cones, engendering some inherent directionality to graphene's electronic properties that did not exist before. This anisotropy manifests itself in the polarization function, and so too in the screening charge density. A finite chemical potential in this case is necessary for any screening to take place in graphene since, without it, there are no electron states near the Fermi level to polarize. Both in the strained and unstrained case, decaying oscillations known as Friedel oscillations are observed. The result of strain is a multifaceted anisotropy of the charge distribution: the amplitude, frequency, and the position of the first peak in the oscillations are each varied depending on the direction one observes. In the second system, extreme strain in graphene leads to a merging of Dirac cones, yielding a transition to a new energy spectrum. This band structure is unusual in that it becomes quadratic along the direction of strain

  11. Using tri-axial accelerometers to identify wild polar bear behaviors

    Science.gov (United States)

    Pagano, Anthony M.; Rode, Karyn D.; Cutting, A.; Owen, M.A.; Jensen, S.; Ware, J.V.; Robbins, C.T.; Durner, George M.; Atwood, Todd C.; Obbard, M.E.; Middel, K.R.; Thiemann, G.W.; Williams, T.M.

    2017-01-01

    Tri-axial accelerometers have been used to remotely identify the behaviors of a wide range of taxa. Assigning behaviors to accelerometer data often involves the use of captive animals or surrogate species, as their accelerometer signatures are generally assumed to be similar to those of their wild counterparts. However, this has rarely been tested. Validated accelerometer data are needed for polar bears Ursus maritimus to understand how habitat conditions may influence behavior and energy demands. We used accelerometer and water conductivity data to remotely distinguish 10 polar bear behaviors. We calibrated accelerometer and conductivity data collected from collars with behaviors observed from video-recorded captive polar bears and brown bears U. arctos, and with video from camera collars deployed on free-ranging polar bears on sea ice and on land. We used random forest models to predict behaviors and found strong ability to discriminate the most common wild polar bear behaviors using a combination of accelerometer and conductivity sensor data from captive or wild polar bears. In contrast, models using data from captive brown bears failed to reliably distinguish most active behaviors in wild polar bears. Our ability to discriminate behavior was greatest when species- and habitat-specific data from wild individuals were used to train models. Data from captive individuals may be suitable for calibrating accelerometers, but may provide reduced ability to discriminate some behaviors. The accelerometer calibrations developed here provide a method to quantify polar bear behaviors to evaluate the impacts of declines in Arctic sea ice.

  12. An analysis of heat conduction in polar bear hairs using one-dimensional fractional model

    Directory of Open Access Journals (Sweden)

    Zhu Wei-Hong

    2016-01-01

    Full Text Available Hairs of a polar bear are of superior properties such as the excellent thermal protection. The polar bears can perennially live in an extremely cold environment and can maintain body temperature at around 37 °C. Why do polar bears can resist such cold environment? Its membrane-pore structure plays an important role. In the previous work, we established a 1-D fractional heat conduction equation to reveal the hidden mechanism for the hairs. In this paper, we further discuss solutions and parameters of the equation established and analyze heat conduction in polar bear hairs.

  13. Sea-ice indicators of polar bear habitat

    Directory of Open Access Journals (Sweden)

    H. L. Stern

    2016-09-01

    Full Text Available Nineteen subpopulations of polar bears (Ursus maritimus are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology – the cycle of biological events – is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat on its way to the summer minimum or rises above the threshold (advance on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979–2014 mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from −3 to −9 days decade−1 in spring and from +3 to +9 days decade−1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of −7 to −19 days decade−1, with larger trends in the Barents Sea and central Arctic Basin. The June–October sea-ice concentration is declining in all regions at rates ranging from −1 to −9 percent decade−1. These sea-ice metrics (or indicators of habitat change were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in

  14. Sea-ice indicators of polar bear habitat

    Science.gov (United States)

    Stern, Harry L.; Laidre, Kristin L.

    2016-09-01

    Nineteen subpopulations of polar bears (Ursus maritimus) are found throughout the circumpolar Arctic, and in all regions they depend on sea ice as a platform for traveling, hunting, and breeding. Therefore polar bear phenology - the cycle of biological events - is linked to the timing of sea-ice retreat in spring and advance in fall. We analyzed the dates of sea-ice retreat and advance in all 19 polar bear subpopulation regions from 1979 to 2014, using daily sea-ice concentration data from satellite passive microwave instruments. We define the dates of sea-ice retreat and advance in a region as the dates when the area of sea ice drops below a certain threshold (retreat) on its way to the summer minimum or rises above the threshold (advance) on its way to the winter maximum. The threshold is chosen to be halfway between the historical (1979-2014) mean September and mean March sea-ice areas. In all 19 regions there is a trend toward earlier sea-ice retreat and later sea-ice advance. Trends generally range from -3 to -9 days decade-1 in spring and from +3 to +9 days decade-1 in fall, with larger trends in the Barents Sea and central Arctic Basin. The trends are not sensitive to the threshold. We also calculated the number of days per year that the sea-ice area exceeded the threshold (termed ice-covered days) and the average sea-ice concentration from 1 June through 31 October. The number of ice-covered days is declining in all regions at the rate of -7 to -19 days decade-1, with larger trends in the Barents Sea and central Arctic Basin. The June-October sea-ice concentration is declining in all regions at rates ranging from -1 to -9 percent decade-1. These sea-ice metrics (or indicators of habitat change) were designed to be useful for management agencies and for comparative purposes among subpopulations. We recommend that the National Climate Assessment include the timing of sea-ice retreat and advance in future reports.

  15. Crescentic glomerulonephritis in a polar bear (Ursus maritimus).

    Science.gov (United States)

    Baba, Hiroshi; Kudo, Tomoo; Makino, Yoshinori; Mochizuki, Yasumasa; Takagi, Takayo; Une, Yumi

    2013-11-01

    Spontaneous crescentic glomerulonephritis (CrGN) in animals has only been reported in dog and sheep. We report the pathological features of CrGN in a 17-year-old male polar bear that died due to renal failure. Histologically, the lesions were characterized by fibrocellular crescents, adhesion between Bowman's capsule and the glomerular capillary tuft and an increase in the mesangial matrix in glomeruli. The proliferating cells in the crescent were partly immunopositive for cytokeratin and intensely positive for vimentin, WT-1 and α-smooth muscle actin, suggesting they originated from parietal epithelial cells. Ultrastructually, thickening of the glomerular basement membrane and loss of epithelial cell foot processes were observed with electron-dense deposits.

  16. Crescentic Glomerulonephritis in a Polar Bear (Ursus maritimus)

    Science.gov (United States)

    BABA, Hiroshi; KUDO, Tomoo; MAKINO, Yoshinori; MOCHIZUKI, Yasumasa; TAKAGI, Takayo; UNE, Yumi

    2013-01-01

    ABSTRACT Spontaneous crescentic glomerulonephritis (CrGN) in animals has only been reported in dog and sheep. We report the pathological features of CrGN in a 17-year-old male polar bear that died due to renal failure. Histologically, the lesions were characterized by fibrocellular crescents, adhesion between Bowman’s capsule and the glomerular capillary tuft and an increase in the mesangial matrix in glomeruli. The proliferating cells in the crescent were partly immunopositive for cytokeratin and intensely positive for vimentin, WT-1 and α-smooth muscle actin, suggesting they originated from parietal epithelial cells. Ultrastructually, thickening of the glomerular basement membrane and loss of epithelial cell foot processes were observed with electron-dense deposits. PMID:23856758

  17. Polar bears exhibit genome-wide signatures of bioenergetic adaptation to life in the arctic environment.

    Science.gov (United States)

    Welch, Andreanna J; Bedoya-Reina, Oscar C; Carretero-Paulet, Lorenzo; Miller, Webb; Rode, Karyn D; Lindqvist, Charlotte

    2014-02-01

    Polar bears (Ursus maritimus) face extremely cold temperatures and periods of fasting, which might result in more severe energetic challenges than those experienced by their sister species, the brown bear (U. arctos). We have examined the mitochondrial and nuclear genomes of polar and brown bears to investigate whether polar bears demonstrate lineage-specific signals of molecular adaptation in genes associated with cellular respiration/energy production. We observed increased evolutionary rates in the mitochondrial cytochrome c oxidase I gene in polar but not brown bears. An amino acid substitution occurred near the interaction site with a nuclear-encoded subunit of the cytochrome c oxidase complex and was predicted to lead to a functional change, although the significance of this remains unclear. The nuclear genomes of brown and polar bears demonstrate different adaptations related to cellular respiration. Analyses of the genomes of brown bears exhibited substitutions that may alter the function of proteins that regulate glucose uptake, which could be beneficial when feeding on carbohydrate-dominated diets during hyperphagia, followed by fasting during hibernation. In polar bears, genes demonstrating signatures of functional divergence and those potentially under positive selection were enriched in functions related to production of nitric oxide (NO), which can regulate energy production in several different ways. This suggests that polar bears may be able to fine-tune intracellular levels of NO as an adaptive response to control trade-offs between energy production in the form of adenosine triphosphate versus generation of heat (thermogenesis).

  18. Polar bears exhibit genome-wide signatures of bioenergetic adaptation to life in the Arctic environment

    Science.gov (United States)

    Welch, Andreanna J.; Bedoya-Reina, Oscar C.; Carretero-Paulet, Lorenzo; Miller, Webb; Rode, Karyn D.; Lindqvist, Charlotte

    2014-01-01

    Polar bears (Ursus maritimus) face extremely cold temperatures and periods of fasting, which might result in more severe energetic challenges than those experienced by their sister species, the brown bear (U. arctos). We have examined the mitochondrial and nuclear genomes of polar and brown bears to investigate if polar bears demonstrate lineage-specific signals of molecular adaptation in genes associated with cellular respiration/energy production. We observed increased evolutionary rates in the mitochondrial cytochrome c oxidase I gene in polar but not brown bears. An amino acid substitution occurred near the interaction site with a nuclear-encoded subunit of the cytochrome c oxidase complex, and was predicted to lead to a functional change, although the significance of this remains unclear. The nuclear genomes of brown and polar bears demonstrate different adaptations related to cellular respiration. Analyses of the genomes of brown bears exhibited substitutions that may alter the function of proteins that regulate glucose uptake, which could be beneficial when feeding on carbohydrate-dominated diets during hyperphagia, followed by fasting during hibernation. In polar bears, genes demonstrating signatures of functional divergence and those potentially under positive selection were enriched in functions related to production of nitric oxide, which can regulate energy production in several different ways. This suggests that polar bears may be able to fine-tune intracellular levels of nitric oxide as an adaptive response to control trade-offs between energy production in the form of ATP versus generation of heat (thermogenesis).

  19. Rebuttal of "Polar bear population forecasts: a public-policy forecasting audit"

    Science.gov (United States)

    Steven C. Amstrup; Hal Caswell; Eric DeWeaver; Ian Stirling; David C. Douglas; Bruce G. Marcot; Christine M. Hunter

    2009-01-01

    Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears (Ursus maritimus). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior...

  20. Circumpolar contaminant concentrations in polar bears (Ursus maritimus) and potential population-level effects

    NARCIS (Netherlands)

    Nuijten, R.J.M.; Hendriks, A.J.; Jenssen, B.M.; Schipper, A.M.

    2016-01-01

    Abstract Polar bears (Ursus maritimus) currently receive much attention in the context of global climate change. However, there are other stressors that might threaten the viability of polar bear populations as well, such as exposure to anthropogenic pollutants. Lipophilic organic compounds

  1. A new fractional derivative and its application to explanation of polar bear hairs

    Directory of Open Access Journals (Sweden)

    Ji-Huan He

    2016-04-01

    Full Text Available A new fractional derivative is defined through the variational iteration method, and its application in explaining the excellent thermal protection of polar bear hairs is elucidated. The fractal porosity of its inner structure makes a polar bear mathematically adapted for living in a harsh Arctic region.

  2. PREVALENCE OF ANTIBODIES AGAINST TOXOPLASMA GONDII IN POLAR BEARS (URSUS MARITIMUS) FROM SVALBARD AND EAST GREENLAND

    Science.gov (United States)

    Serum samples from 419 polar bears (Ursus maritimus) from Svalbard and the Barents Sea (collected 1990 - 2000) and 108 polar bears from East Greenland (collected 1999 - 2004) were assayed for antibodies against Toxoplasma gondii using the modified agglutination test (MAT). Antibody prevalences were ...

  3. Fault diagnosis of rolling bearing based on cyclic spectrum density

    International Nuclear Information System (INIS)

    Shi Qingfeng; Yan Junming; Zhang Yanhong

    2009-01-01

    The paper considered the vibration signals of rotating equipment as cyclo stationary signals through analyzing the features of this kind of signals. Based on the analytic method of cyclic spectrum density, the paper pointed out that the impact frequency could be extracted effectively with the help of scanning cyclic frequency domain. The validity of the method of cyclic spectrum density is proved by simulating signals and the method is applied to the diagnosis of rolling bearings. (authors)

  4. Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline

    Science.gov (United States)

    Edwards, Ceiridwen J.; Suchard, Marc A.; Lemey, Philippe; Welch, John J.; Barnes, Ian; Fulton, Tara L.; Barnett, Ross; O’Connell, Tamsin C.; Coxon, Peter; Monaghan, Nigel; Valdiosera, Cristina E.; Lorenzen, Eline D.; Willerslev, Eske; Baryshnikov, Gennady F.; Rambaut, Andrew; Thomas, Mark G.; Bradley, Daniel G.; Shapiro, Beth

    2015-01-01

    Summary Background Polar bears (Ursus maritimus) are among those species most susceptible to the rapidly changing arctic climate, and their survival is of global concern. Despite this, little is known about polar bear species history. Future conservation strategies would significantly benefit from an understanding of basic evolutionary information, such as the timing and conditions of their initial divergence from brown bears (U. arctos) or their response to previous environmental change. Results We used a spatially explicit phylogeographic model to estimate the dynamics of 242 brown bear and polar bear matrilines sampled throughout the last 120,000 years and across their present and past geographic ranges. Our results show that the present distribution of these matrilines was shaped by a combination of regional stability and rapid, long-distance dispersal from ice-age refugia. In addition, hybridization between polar bears and brown bears may have occurred multiple times throughout the Late Pleistocene. Conclusions The reconstructed matrilineal history of brown and polar bears has two striking features. First, it is punctuated by dramatic and discrete climate-driven dispersal events. Second, opportunistic mating between these two species as their ranges overlapped has left a strong genetic imprint. In particular, a likely genetic exchange with extinct Irish brown bears forms the origin of the modern polar bear matriline. This suggests that interspecific hybridization not only may be more common than previously considered but may be a mechanism by which species deal with marginal habitats during periods of environmental deterioration. PMID:21737280

  5. Estimating Allee dynamics before they can be observed: polar bears as a case study.

    Directory of Open Access Journals (Sweden)

    Péter K Molnár

    Full Text Available Allee effects are an important component in the population dynamics of numerous species. Accounting for these Allee effects in population viability analyses generally requires estimates of low-density population growth rates, but such data are unavailable for most species and particularly difficult to obtain for large mammals. Here, we present a mechanistic modeling framework that allows estimating the expected low-density growth rates under a mate-finding Allee effect before the Allee effect occurs or can be observed. The approach relies on representing the mechanisms causing the Allee effect in a process-based model, which can be parameterized and validated from data on the mechanisms rather than data on population growth. We illustrate the approach using polar bears (Ursus maritimus, and estimate their expected low-density growth by linking a mating dynamics model to a matrix projection model. The Allee threshold, defined as the population density below which growth becomes negative, is shown to depend on age-structure, sex ratio, and the life history parameters determining reproduction and survival. The Allee threshold is thus both density- and frequency-dependent. Sensitivity analyses of the Allee threshold show that different combinations of the parameters determining reproduction and survival can lead to differing Allee thresholds, even if these differing combinations imply the same stable-stage population growth rate. The approach further shows how mate-limitation can induce long transient dynamics, even in populations that eventually grow to carrying capacity. Applying the models to the overharvested low-density polar bear population of Viscount Melville Sound, Canada, shows that a mate-finding Allee effect is a plausible mechanism for slow recovery of this population. Our approach is generalizable to any mating system and life cycle, and could aid proactive management and conservation strategies, for example, by providing a priori

  6. Estimating Allee dynamics before they can be observed: polar bears as a case study.

    Science.gov (United States)

    Molnár, Péter K; Lewis, Mark A; Derocher, Andrew E

    2014-01-01

    Allee effects are an important component in the population dynamics of numerous species. Accounting for these Allee effects in population viability analyses generally requires estimates of low-density population growth rates, but such data are unavailable for most species and particularly difficult to obtain for large mammals. Here, we present a mechanistic modeling framework that allows estimating the expected low-density growth rates under a mate-finding Allee effect before the Allee effect occurs or can be observed. The approach relies on representing the mechanisms causing the Allee effect in a process-based model, which can be parameterized and validated from data on the mechanisms rather than data on population growth. We illustrate the approach using polar bears (Ursus maritimus), and estimate their expected low-density growth by linking a mating dynamics model to a matrix projection model. The Allee threshold, defined as the population density below which growth becomes negative, is shown to depend on age-structure, sex ratio, and the life history parameters determining reproduction and survival. The Allee threshold is thus both density- and frequency-dependent. Sensitivity analyses of the Allee threshold show that different combinations of the parameters determining reproduction and survival can lead to differing Allee thresholds, even if these differing combinations imply the same stable-stage population growth rate. The approach further shows how mate-limitation can induce long transient dynamics, even in populations that eventually grow to carrying capacity. Applying the models to the overharvested low-density polar bear population of Viscount Melville Sound, Canada, shows that a mate-finding Allee effect is a plausible mechanism for slow recovery of this population. Our approach is generalizable to any mating system and life cycle, and could aid proactive management and conservation strategies, for example, by providing a priori estimates of minimum

  7. Characterization of blood lipoproteins and validation of cholesterol and triacylglycerol assays for free-ranging polar bears (Ursus maritimus).

    Science.gov (United States)

    Whiteman, John P; Frank, Nicholas; Greller, Katie A; Harlow, Henry J; Ben-David, Merav

    2013-05-01

    Blood triacylglycerol (TG) and lipoproteins are important variables for evaluating nutritional status of wildlife, but measurements are often expensive and difficult. Performance of a small, portable blood analyzer intended for human medical diagnostics was evaluated in measuring these variables in plasma and serum from free-ranging polar bears (Ursus maritimus), which are experiencing nutritional stress related to sea ice loss. The analyzer accurately tracked changes in concentration of total cholesterol (Ctotal), cholesterol associated with high-density lipoprotein (CHDL), and TG during a validation protocol of diluting samples and spiking them with exogenous cholesterol and glycerol. Values of Ctotal and TG agreed well with values obtained by other methods (ultracentrifugation followed by colorimetric assays); agreement was variable for values of cholesterol associated with specific lipoproteins. Similar to a study of captive polar bears, ultracentrifugation methods revealed greater TG in very low-density lipoproteins than in low-density lipoprotein, which is unusual and merits additional study.

  8. Complete mitochondrial genome of a Pleistocene jawbone unveils the origin of polar bear

    OpenAIRE

    Lindqvist, Charlotte; Schuster, Stephan C.; Sun, Yazhou; Talbot, Sandra L.; Qi, Ji; Ratan, Aakrosh; Tomsho, Lynn P.; Kasson, Lindsay; Zeyl, Eve; Aars, Jon; Miller, Webb; Ingólfsson, Ólafur; Bachmann, Lutz; Wiig, Øystein

    2010-01-01

    The polar bear has become the flagship species in the climate-change discussion. However, little is known about how past climate impacted its evolution and persistence, given an extremely poor fossil record. Although it is undisputed from analyses of mitochondrial (mt) DNA that polar bears constitute a lineage within the genetic diversity of brown bears, timing estimates of their divergence have differed considerably. Using next-generation sequencing technology, we have generated a complete, ...

  9. Ancient hybridization and an Irish origin for the modern polar bear matriline

    DEFF Research Database (Denmark)

    Edwards, Ceiridwen J.; Suchard, Marc A.; Lemey, Philippe

    2011-01-01

    Polar bears (Ursus maritimus) are among those species most susceptible to the rapidly changing arctic climate, and their survival is of global concern. Despite this, little is known about polar bear species history. Future conservation strategies would significantly benefit from an understanding...... of basic evolutionary information, such as the timing and conditions of their initial divergence from brown bears (U. arctos) or their response to previous environmental change....

  10. High contributions of sea ice derived carbon in polar bear (Ursus maritimus) tissue.

    OpenAIRE

    Brown, TA; Galicia, MP; Thiemann, GW; Belt, ST; Yurkowski, DJ; Dyck, MG

    2018-01-01

    Polar bears (Ursus maritimus) rely upon Arctic sea ice as a physical habitat. Consequently, conservation assessments of polar bears identify the ongoing reduction in sea ice to represent a significant threat to their survival. However, the additional role of sea ice as a potential, indirect, source of energy to bears has been overlooked. Here we used the highly branched isoprenoid lipid biomarker-based index (H-Print) approach in combination with quantitative fatty acid signature analysis to ...

  11. 75 FR 65507 - U.S.-Russia Polar Bear Commission Adopts an Annual Taking Limit for the Alaska-Chukotka Polar...

    Science.gov (United States)

    2010-10-25

    ...-FY10] U.S.-Russia Polar Bear Commission Adopts an Annual Taking Limit for the Alaska-Chukotka Polar Bear Population AGENCY: Fish and Wildlife Service, Interior. ACTION: Notice. SUMMARY: On June 9, 2010, by unanimous vote, the U.S.-Russia Polar Bear Commission established by the ``Agreement Between the...

  12. Variation in winter diet of southern Beaufort Sea polar bears inferred from stable isotope analysis

    Science.gov (United States)

    Bentzen, T.W.; Follmann, Erich H.; Amstrup, Steven C.; York, G.S.; Wooller, M.J.; O'Hara, T. M.

    2007-01-01

    Ringed seals (Phoca hispida Schreber, 1775 = Pusa hispida (Schreber, 1775)) and bearded seals (Erignathus barbatus (Erxleben, 1777)) represent the majority of the polar bear (Ursus maritimus Phipps, 1774) annual diet. However, remains of lower trophic level bowhead whales (Balaena mysticetus L., 1758) are available in the southern Beaufort Sea and their dietary contribution to polar bears has been unknown. We used stable isotope (13C/12C, δ13C, 15N/14N, and δ15N) analysis to determine the diet composition of polar bears sampled along Alaska’s Beaufort Sea coast in March and April 2003 and 2004. The mean δ15N values of polar bear blood cells were 19.5‰ (SD = 0.7‰) in 2003 and 19.9‰ (SD = 0.7‰) in 2004. Mixing models indicated bowhead whales composed 11%–26% (95% CI) of the diets of sampled polar bears in 2003, and 0%–14% (95% CI) in 2004. This suggests significant variability in the proportion of lower trophic level prey in polar bear diets among individuals and between years. Polar bears depend on sea ice for hunting seals, and the temporal and spatial availabilities of sea ice are projected to decline. Consumption of low trophic level foods documented here suggests bears may increasingly scavenge such foods in the future.

  13. Harvesting wildlife affected by climate change: a modelling and management approach for polar bears

    Science.gov (United States)

    Regehr, Eric V.; Wilson, Ryan R.; Rode, Karyn D.; Runge, Michael C.; Stern, Harry

    2017-01-01

    The conservation of many wildlife species requires understanding the demographic effects of climate change, including interactions between climate change and harvest, which can provide cultural, nutritional or economic value to humans.We present a demographic model that is based on the polar bear Ursus maritimus life cycle and includes density-dependent relationships linking vital rates to environmental carrying capacity (K). Using this model, we develop a state-dependent management framework to calculate a harvest level that (i) maintains a population above its maximum net productivity level (MNPL; the population size that produces the greatest net increment in abundance) relative to a changing K, and (ii) has a limited negative effect on population persistence.Our density-dependent relationships suggest that MNPL for polar bears occurs at approximately 0·69 (95% CI = 0·63–0·74) of K. Population growth rate at MNPL was approximately 0·82 (95% CI = 0·79–0·84) of the maximum intrinsic growth rate, suggesting relatively strong compensation for human-caused mortality.Our findings indicate that it is possible to minimize the demographic risks of harvest under climate change, including the risk that harvest will accelerate population declines driven by loss of the polar bear's sea-ice habitat. This requires that (i) the harvest rate – which could be 0 in some situations – accounts for a population's intrinsic growth rate, (ii) the harvest rate accounts for the quality of population data (e.g. lower harvest when uncertainty is large), and (iii) the harvest level is obtained by multiplying the harvest rate by an updated estimate of population size. Environmental variability, the sex and age of removed animals and risk tolerance can also affect the harvest rate.Synthesis and applications. We present a coupled modelling and management approach for wildlife that accounts for climate change and can be used to balance trade-offs among multiple

  14. Harvesting wildlife affected by climate change: a modelling and management approach for polar bears.

    Science.gov (United States)

    Regehr, Eric V; Wilson, Ryan R; Rode, Karyn D; Runge, Michael C; Stern, Harry L

    2017-10-01

    The conservation of many wildlife species requires understanding the demographic effects of climate change, including interactions between climate change and harvest, which can provide cultural, nutritional or economic value to humans.We present a demographic model that is based on the polar bear Ursus maritimus life cycle and includes density-dependent relationships linking vital rates to environmental carrying capacity ( K ). Using this model, we develop a state-dependent management framework to calculate a harvest level that (i) maintains a population above its maximum net productivity level (MNPL; the population size that produces the greatest net increment in abundance) relative to a changing K , and (ii) has a limited negative effect on population persistence.Our density-dependent relationships suggest that MNPL for polar bears occurs at approximately 0·69 (95% CI = 0·63-0·74) of K . Population growth rate at MNPL was approximately 0·82 (95% CI = 0·79-0·84) of the maximum intrinsic growth rate, suggesting relatively strong compensation for human-caused mortality.Our findings indicate that it is possible to minimize the demographic risks of harvest under climate change, including the risk that harvest will accelerate population declines driven by loss of the polar bear's sea-ice habitat. This requires that (i) the harvest rate - which could be 0 in some situations - accounts for a population's intrinsic growth rate, (ii) the harvest rate accounts for the quality of population data (e.g. lower harvest when uncertainty is large), and (iii) the harvest level is obtained by multiplying the harvest rate by an updated estimate of population size. Environmental variability, the sex and age of removed animals and risk tolerance can also affect the harvest rate. Synthesis and applications . We present a coupled modelling and management approach for wildlife that accounts for climate change and can be used to balance trade-offs among multiple conservation

  15. DISTRIBUTION AND MIGRATION OF POLAR BEARS, PACIFIC WALRUSES AND GRAY WHALES DEPENDING ON ICE CONDITIONS IN THE RUSSIAN ARCTIC (17th Symposium on Polar Biology)

    OpenAIRE

    Stanislav, BELIKOV; Andrei, BOLTUNOV; Yuri, GORBUNOV

    1996-01-01

    This report presents a review of available data concerning the influence of ice cover on distribution, density and migration of three species of marine mammals inhabiting the Russian Arctic. Association of marine mammals with ice cover is as follows: (1) the polar bear is distributed in ice zone in the whole year, (2) the walrus is associated with the ice zone only in summer, and (3) the gray whale inhabits the southern area of the ice zone.

  16. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Science.gov (United States)

    Rode, Karyn D; Wilson, Ryan R; Regehr, Eric V; St Martin, Michelle; Douglas, David C; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  17. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    Directory of Open Access Journals (Sweden)

    Karyn D Rode

    Full Text Available Recent observations suggest that polar bears (Ursus maritimus are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013 when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia, highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  18. Climate change and the increasing impact of polar bears on bird populations

    Directory of Open Access Journals (Sweden)

    Jouke eProp

    2015-03-01

    Full Text Available The Arctic is becoming warmer at a high rate, and contractions in the extent of sea ice are currently changing the habitats of marine top-predators dependent on ice. Polar bears (Ursus maritimus depend on sea ice for hunting seals. For these top-predators, longer ice-free seasons are hypothesized to force the bears to hunt for alternative terrestrial food, such as eggs from colonial breeding birds. We analyzed time-series of polar bear observations at four locations on Spitsbergen (Svalbard and one in east Greenland. Summer occurrence of polar bears, measured as the probability of encountering bears and the number of days with bear presence, has increased significantly from the 1970/80s to the present. The shifts in polar bear occurrence coincided with trends for shorter sea ice seasons and less sea ice during the spring in the study area. This resulted in a strong inverse relationship between the probability of bear encounters on land and the length of the sea ice season. Within ten years after their first appearance on land, polar bears had advanced their arrival dates by almost 30 days. Direct observations of nest predation showed that polar bears may severely affect reproductive success of the barnacle goose (Branta leucopsis, common eider (Somateria mollissima and glaucous gull (Larus hyperboreus. Nest predation was strongest in years when the polar bears arrived well before hatch, with more than 90% of all nests being predated. The results are similar to findings from Canada, and large-scale processes, such as climate and subsequent habitat changes, are pinpointed as the most likely drivers in various parts of the Arctic. We suggest that the increasing, earlier appearance of bears on land in summer reflects behavioral adaptations by a small segment of the population to cope with a reduced hunting range on sea ice. This exemplifies how behavioral adaptations may contribute to the cascading effects of climate change.

  19. Is the polar bear (Ursus maritimus) a hibernator? Continued studies on opioids and hibernation

    Science.gov (United States)

    Bruce, David S.; Darling, Nancy K.; Seeland, Katheleen J.; Oeltgen, Peter R.; Nilekani, Sita P.; Amstrup, Steven C.

    1990-01-01

    Polar bear behavior and biochemistry suggest they may have the ability to hibernate year-round, even though this species is not considered to be a true hibernator. This observation, plus the discovery of a hibernation-induced trigger (HIT) in the blood of black bears, prompted the examination of polar bear blood collected thoughout the year for evidence ofr HIT, and to determine if it displayed opioid activity, as black bear blood does. A bioassay was conducted by injected summer 13-lined ground squirrels with serum collected from polar bears at different seasons. One group of squirrels was previously implanted with osmotic pumps containing naloxone. The rest had pumps containing saline. Squirrels with saline pumps all hibernated significantly more than those with naloxone, except the group receiving blood from a November polar bear, observed to be highly active and hyperphagic. An in vitro study, using guinea pig ileum, showed that 400 nM morphine inhibited induced contractions and 100 nM naloxone reversed the inhibition. Ten mg of winter polar bear serum albumin fraction (to which HIT binds in ground squirrels and woodchucks) had a similar inhibiting effect, but naloxone, even at 4,000 nM, didn't reverse it. It is concluded that polar bear contains HIT, that it has an opioid effct, but may not itself be an opioid.

  20. Estimating black bear density using DNA data from hair snares

    Science.gov (United States)

    Gardner, B.; Royle, J. Andrew; Wegan, M.T.; Rainbolt, R.E.; Curtis, P.D.

    2010-01-01

    DNA-based mark-recapture has become a methodological cornerstone of research focused on bear species. The objective of such studies is often to estimate population size; however, doing so is frequently complicated by movement of individual bears. Movement affects the probability of detection and the assumption of closure of the population required in most models. To mitigate the bias caused by movement of individuals, population size and density estimates are often adjusted using ad hoc methods, including buffering the minimum polygon of the trapping array. We used a hierarchical, spatial capturerecapture model that contains explicit components for the spatial-point process that governs the distribution of individuals and their exposure to (via movement), and detection by, traps. We modeled detection probability as a function of each individual's distance to the trap and an indicator variable for previous capture to account for possible behavioral responses. We applied our model to a 2006 hair-snare study of a black bear (Ursus americanus) population in northern New York, USA. Based on the microsatellite marker analysis of collected hair samples, 47 individuals were identified. We estimated mean density at 0.20 bears/km2. A positive estimate of the indicator variable suggests that bears are attracted to baited sites; therefore, including a trap-dependence covariate is important when using bait to attract individuals. Bayesian analysis of the model was implemented in WinBUGS, and we provide the model specification. The model can be applied to any spatially organized trapping array (hair snares, camera traps, mist nests, etc.) to estimate density and can also account for heterogeneity and covariate information at the trap or individual level. ?? The Wildlife Society.

  1. Polychlorinated biphenyls and reproductive hormones in female polar bears at Svalbard.

    Science.gov (United States)

    Haave, Marte; Ropstad, Erik; Derocher, Andrew E; Lie, Elisabeth; Dahl, Ellen; Wiig, Øystein; Skaare, Janneche U; Jenssen, Bjørn Munro

    2003-04-01

    High concentrations of polychlorinated biphenyls (PCBs) in polar bears from Svalbard have increased concern for that population's reproductive health. We examined whether there were associations between the plasma concentrations of PCBs and reproductive hormones [progesterone (P4)] and 17 beta-estradiol (E2)] in free-living female polar bears from Svalbard. Concentrations of P4 depended on reproductive status, and concentrations were lowest in females with offspring--females with cubs and females with yearlings. In these females, the P4 concentrations were positively correlated with plasma sigma PCBs (sum of all analyzed polychlorinated biphenyl congeners) concentrations. The sigma PCBs concentrations explained 27% of the variation in the P4 concentrations. There were no correlations between sigma PCBs and E2 and cortisol in any of the groups of polar bears, or between sigma PCBs and P4 in single polar bears. Although the sigma PCBs-P4 relationship in female polar bears with offspring is not evidence per se of a direct cause-effect association, the results indicate that PCBs may affect levels of P4 in polar bear females. There is a clear need to further assess the hormone balance and population health of polar bears at Svalbard.

  2. Establishing a definition of polar bear (Ursus maritimus) health: A guide to research and management activities

    Science.gov (United States)

    Patyk, Kelly A.; Duncan, Colleen G.; Nol, Pauline; Sonne, C.; Laidre, Kristin L.; Obbard, Martyn E.; Wiig, Øystein; Aars, Jon; Regehr, Eric V.; Gustafson, L.; Atwood, Todd C.

    2015-01-01

    The meaning of health for wildlife and perspectives on how to assess and measure health, are not well characterized. For wildlife at risk, such as some polar bear (Ursus maritimus) subpopulations, establishing comprehensive monitoring programs that include health status is an emerging need. Environmental changes, especially loss of sea ice habitat, have raised concern about polar bear health. Effective and consistent monitoring of polar bear health requires an unambiguous definition of health. We used the Delphi method of soliciting and interpreting expert knowledge to propose a working definition of polar bear health and to identify current concerns regarding health, challenges in measuring health, and important metrics for monitoring health. The expert opinion elicited through the exercise agreed that polar bear health is defined by characteristics and knowledge at the individual, population, and ecosystem level. The most important threats identified were in decreasing order: climate change, increased nutritional stress, chronic physiological stress, harvest management, increased exposure to contaminants, increased frequency of human interaction, diseases and parasites, and increased exposure to competitors. Fifteen metrics were identified to monitor polar bear health. Of these, indicators of body condition, disease and parasite exposure, contaminant exposure, and reproductive success were ranked as most important. We suggest that a cumulative effects approach to research and monitoring will improve the ability to assess the biological, ecological, and social determinants of polar bear health and provide measurable objectives for conservation goals and priorities and to evaluate progress.

  3. Establishing a definition of polar bear (Ursus maritimus) health: a guide to research and management activities.

    Science.gov (United States)

    Patyk, Kelly A; Duncan, Colleen; Nol, Pauline; Sonne, Christian; Laidre, Kristin; Obbard, Martyn; Wiig, Øystein; Aars, Jon; Regehr, Eric; Gustafson, Lori L; Atwood, Todd

    2015-05-01

    The meaning of health for wildlife and perspectives on how to assess and measure health, are not well characterized. For wildlife at risk, such as some polar bear (Ursus maritimus) subpopulations, establishing comprehensive monitoring programs that include health status is an emerging need. Environmental changes, especially loss of sea ice habitat, have raised concern about polar bear health. Effective and consistent monitoring of polar bear health requires an unambiguous definition of health. We used the Delphi method of soliciting and interpreting expert knowledge to propose a working definition of polar bear health and to identify current concerns regarding health, challenges in measuring health, and important metrics for monitoring health. The expert opinion elicited through the exercise agreed that polar bear health is defined by characteristics and knowledge at the individual, population, and ecosystem level. The most important threats identified were in decreasing order: climate change, increased nutritional stress, chronic physiological stress, harvest management, increased exposure to contaminants, increased frequency of human interaction, diseases and parasites, and increased exposure to competitors. Fifteen metrics were identified to monitor polar bear health. Of these, indicators of body condition, disease and parasite exposure, contaminant exposure, and reproductive success were ranked as most important. We suggest that a cumulative effects approach to research and monitoring will improve the ability to assess the biological, ecological, and social determinants of polar bear health and provide measurable objectives for conservation goals and priorities and to evaluate progress. Published by Elsevier B.V.

  4. Projected polar bear sea ice habitat in the Canadian Arctic Archipelago.

    Science.gov (United States)

    Hamilton, Stephen G; Castro de la Guardia, Laura; Derocher, Andrew E; Sahanatien, Vicki; Tremblay, Bruno; Huard, David

    2014-01-01

    Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus) have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 - 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling. Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands. Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

  5. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines

    Science.gov (United States)

    Laidre, K. L.; Regehr, E. V.; Akcakaya, H. R.; Amstrup, S. C.; Atwood, T.; Lunn, N.; Obbard, M.; Stern, H. L., III; Thiemann, G.; Wiig, O.

    2016-12-01

    Loss of Arctic sea ice due to climate change is the most serious threat to polar bears (Ursus maritimus) throughout their circumpolar range. We performed a data-based sensitivity analysis with respect to this threat by evaluating the potential response of the global polar bear population to projected sea-ice conditions. We conducted 1) an assessment of generation length for polar bears, 2) developed of a standardized sea-ice metric representing important habitat characteristics for the species; and 3) performed population projections over three generations, using computer simulation and statistical models representing alternative relationships between sea ice and polar bear abundance. Using three separate approaches, the median percent change in mean global population size for polar bears between 2015 and 2050 ranged from -4% (95% CI = -62%, 50%) to -43% (95% CI = -76%, -20%). Results highlight the potential for large reductions in the global population if sea-ice loss continues. They also highlight the large amount of uncertainty in statistical projections of polar bear abundance and the sensitivity of projections to plausible alternative assumptions. The median probability of a reduction in the mean global population size of polar bears greater than 30% over three generations was approximately 0.71 (range 0.20-0.95. The median probability of a reduction greater than 50% was approximately 0.07 (range 0-0.35), and the probability of a reduction greater than 80% was negligible.

  6. Projected polar bear sea ice habitat in the Canadian Arctic Archipelago.

    Directory of Open Access Journals (Sweden)

    Stephen G Hamilton

    Full Text Available Sea ice across the Arctic is declining and altering physical characteristics of marine ecosystems. Polar bears (Ursus maritimus have been identified as vulnerable to changes in sea ice conditions. We use sea ice projections for the Canadian Arctic Archipelago from 2006 - 2100 to gain insight into the conservation challenges for polar bears with respect to habitat loss using metrics developed from polar bear energetics modeling.Shifts away from multiyear ice to annual ice cover throughout the region, as well as lengthening ice-free periods, may become critical for polar bears before the end of the 21st century with projected warming. Each polar bear population in the Archipelago may undergo 2-5 months of ice-free conditions, where no such conditions exist presently. We identify spatially and temporally explicit ice-free periods that extend beyond what polar bears require for nutritional and reproductive demands.Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.

  7. Potential Arctic sea ice refuge for sustaining a remnant polar bear population (Invited)

    Science.gov (United States)

    Durner, G. M.; Amstrup, S. C.; Douglas, D. C.; Gautier, D. L.

    2010-12-01

    Polar bears depend on sea ice as a platform from which they capture seals. Sea ice availability must be spatially and temporally adequate for birth and weaning of seal pups, and to maximize seal hunting opportunities for polar bears. Projected declines in the spatial and temporal extent of summer and autumn sea ice could potentially limit the ability of polar bears to build up body stores sufficient to maintain reproductive fitness. General circulation models, however, suggest that summer and autumn sea ice may persist in the shelf waters of the Canadian Archipelago and northern Greenland adjacent to the Arctic basin. While winter-formed ice is important, a primary mechanism for sea ice accumulation in this region is by mechanical thickening of the sea ice facilitated by convergent forces from the Beaufort Gyre and the Transpolar Drift Stream. Collectively these areas could provide a polar bear refugium when other regions have lost the sea ice necessary to support viable populations. The potential for a polar bear refugium, however, must include other resource considerations. Projected declines of sea ice in the Northwest Passage may expose polar bears to hazards related to increase shipping and other commerce. Increasing global demands and limited opportunities elsewhere make the Arctic an increasingly attractive area for petroleum exploration. The Canadian Archipelago coincides with the Sverdrup basin, where petroleum accumulations have already been discovered but as yet are undeveloped. The Lincoln Sea Basin offshore of northern Greenland has the geological possibility of significant petroleum accumulations, and northeastern Greenland is one of the most prospective areas in the Arctic for undiscovered oil. Activities associated with commerce and petroleum development could reduce the potential viability of the region as a polar bear refugium. Hence, if the goal is a sustainable (albeit reduced) polar bear population, important considerations include commerce

  8. Behavioral decisions for managing social distance and aggression in captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Renner, Michael J; Kelly, Aislinn L

    2006-01-01

    The polar bear (Ursus maritimus) in most zoos attracts high levels of public attention and can play an important role in conservation education. Polar bears in the wild are typically solitary; bears in captivity often house socially. This study reported behavioral evidence on how bears manage this situation and whether proximity leads to aggression. The study recorded location and behavior once per minute for 106 hr for 2 female polar bears at the Philadelphia Zoo; the samples represented all times of day bears spent in the enclosure (off-exhibit time spent in separate, indoor dens). When changing locations, 1 bear more frequently moved away from the other, effecting a net increase in interindividual distance. When either bear moved into an adjacent zone, 1 typically moved away. The bears occupied the same enclosure zone for a low proportion of time; proximity did not routinely lead to overt aggression. These data indicate polar bears make behavioral decisions, minimizing aggression, to manage social distance and that enclosure designers for solitary species--to facilitate social avoidance--should consider using topographical complexity and multiple pathways throughout.

  9. 77 FR 4492 - Endangered and Threatened Wildlife and Plants; Reissuance of Interim Special Rule for the Polar Bear

    Science.gov (United States)

    2012-01-30

    ... Special Rule for the Polar Bear AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule. SUMMARY... order in regard to Misc. No. 08- 764 (EGS) MDL Docket No. 1993 IN RE: POLAR BEAR ENDANGERED SPECIES ACT... December 16, 2008, final special rule for the polar bear (73 FR 76249). The Court further ordered that in...

  10. 75 FR 76085 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Polar Bear...

    Science.gov (United States)

    2010-12-07

    ... Threatened Wildlife and Plants; Designation of Critical Habitat for the Polar Bear (Ursus maritimus) in the... Wildlife and Plants; Designation of Critical Habitat for the Polar Bear (Ursus maritimus) in the United... Wildlife Service (Service), designate critical habitat for polar bear (Ursus maritimus) populations in the...

  11. 75 FR 24545 - Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Polar Bear...

    Science.gov (United States)

    2010-05-05

    ... Critical Habitat for the Polar Bear in the United States AGENCY: Fish and Wildlife Service, Interior... designation of critical habitat for the polar bear (Ursus maritimus) under the Endangered Species Act of 1973... for the polar bear and on the DEA, and an amended required determinations section of the proposal. We...

  12. 78 FR 11766 - Endangered and Threatened Wildlife and Plants; Special Rule for the Polar Bear Under Section 4(d...

    Science.gov (United States)

    2013-02-20

    ...'' definition requires evidence of demonstrable injury or death to polar bears. The breadth of the MMPA... Polar Bear Under Section 4(d) of the Endangered Species Act AGENCY: Fish and Wildlife Service, Interior... polar bear (Ursus maritimus), while also including appropriate prohibitions from section 9(a)(1) of the...

  13. Xenoendocrine pollutants may reduce size of sexual organs in East Greenland polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Sonne, Christian; Leifsson, Páll Skuli; Dietz, Rune

    2006-01-01

    Reproductive organs from 55 male and 44 female East Greenland polar bears were examined to investigate the potential negative impact from organohalogen pollutants (OHCs). Multiple regressions normalizing for age showed a significant inverse relationship between OHCs and testis length and baculum.......01) and uterine horn length and HCB (p = 0.02). The study suggests thatthere is an impact from xenoendocrine pollutants on the size of East Greenland polar bear genitalia. This may pose a riskto this polar bear subpopulation in the future because of reduced sperm and egg quality/quantity and uterus and penis size...

  14. Zinc, cadmium, mercury and selenium in polar bears (Ursus maritimus) from Central East Greenland

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, R. [Greenland Environmental Research Institute, Copenhagen (Denmark); Born, E.W. [Greenland Fisheries Research Institute, Copenhagen (Denmark); Agger, C.T. [National Environmental Research Institute, Roskilde (Denmark); Nielsen, C.O. [Ravnsnaesvej, Birkerod (Denmark)

    1995-02-01

    Muscle, liver, and kidney tissues from 38 polar bears (Ursus maritimus) caught in the Scoresby Sound area, Central East Greenland, were analysed for zinc, cadmium, mercury and selenium. In general, cadmium concentrations were low in muscle, liver and kidney tissue. This finding can be explained by low cadmium levels in the blubber of ringed seals. The concentration of mercury in muscle tissue was low, whereas concentrations in liver and kidney tissue were relatively high. Mercury and cadmium were positively correlated with age in liver and kidney. Zinc was positively correlated with in kidney, and selenium was correlated with age in liver. Contrary to other marine mammals, polar bears had higher mercury levels in the kidneys than in the liver. In all three tissues polar bears had significantly lower cadmium levels than ringed seals from the same area. Mercury levels were significantly lower in the muscle tissue of polar bears than in ringed seals, where-as levels in the liver and kidney were significantly higher. The previous geographic trend for cadmium and mercury found in Canadian polar bears could be extended to cover East Greenland as well. Hence cadmium levels were higher in Greenland than in Canada, while the opposite was the case for mercury. Greenland polar bears had higher mercury and cadmium contents in livers and kidneys than polar bears from Svalbard. The mercury levels in muscle and liver tissue from polar bears from East Greenland were twice as high as found in bears from western Alaska, but half the levels found in northern Alaska. Cadmium and zinc were partially correlated in kidney tissue, and this was found for mercury and selenium as well. Cadmium and zinc showed molar ratios close to unity with the highest concentrations occurring in kidney tissue, while the levels of zinc exceeded cadmium in muscle and liver tissue by up to several decades. Mercury and selenium showed molar ratios close to unity in liver and kidneys. 56 refs., 5 figs., 6 tabs.

  15. Increased Arctic Sea Ice Drift Alters Polar Bear Movements and Energetics

    Science.gov (United States)

    Douglas, D. C.; Durner, G. M.; Albeke, S. E.; Whiteman, J. P.; Amstrup, S. C.; Richardson, E.; Wilson, R. R.; Ben-David, M.

    2015-12-01

    Recent thinning of Arctic sea ice has increased its drift from currents and winds. Increased ice drift could affect movements and energy balance of polar bears (Ursus maritimus) which rely, almost exclusively, on this substrate for hunting seals. Foraging by polar bears is a relatively sedentary behavior, as they typically capture their main prey by waiting at breathing holes, where seals haul-out along leads, or by short-distance stalking. We examined the response of polar bears to ice drift in the Beaufort (BS) and Chukchi (CS) seas, and between two periods with different sea ice characteristics: 1987-1998 and 1999-2013. We used satellite-tracked adult female polar bear locations, standardized by a continuous-time correlated random walk, coupled with modeled ice drift, to estimate displacement and drift-corrected bear movements along east-west and north-south axes. Sea ice drift in both regions increased with greater westward and more extreme northward and southward rates from 1987-1998 to 1999-2013. Polar bears responded with greater eastward movements and, in the CS greater movements north and south. We show that efforts by polar bears to compensate for greater westward ice drift in recent years translated into a model-derived estimate of 5.7-7.2% increase in energy expenditure. We also estimated that polar bears increased their travel time 18-20% between the two time periods, suggesting time allocated to foraging was reduced. Increased energetic costs and travel time resulting from greater ice drift, in conjunction with ongoing habitat loss, suggest that recent changes to Arctic sea ice may affect movements and energy balance of polar bears.

  16. Recent observations of intraspecific predation and cannibalism among polar bears in the southern Beaufort Sea

    Science.gov (United States)

    Amstrup, Steven C.; Stirling, I.; Smith, T.S.; Perham, C.; Thiemann, G.W.

    2006-01-01

    Intraspecific killing has been reported among polar bears (Ursus maritimus), brown bears (U. arctos), and black bears (U. americanus). Although cannibalism is one motivation for such killings, the ecological factors mediating such events are poorly understood. Between 24 January and 10 April 2004, we confirmed three instances of intraspecific predation and cannibalism in the Beaufort Sea. One of these, the first of this type ever reported for polar bears, was a parturient female killed at her maternal den. The predating bear was hunting in a known maternal denning area and apparently discovered the den by scent. A second predation event involved an adult female and cub recently emerged from their den, and the third involved a yearling male. During 24 years of research on polar bears in the southern Beaufort Sea region of northern Alaska and 34 years in northwestern Canada, we have not seen other incidents of polar bears stalking, killing, and eating other polar bears. We hypothesize that nutritional stresses related to the longer ice-free seasons that have occurred in the Beaufort Sea in recent years may have led to the cannibalism incidents we observed in 2004. ?? Springer-Verlag 2006.

  17. Correlation between the Flux Density and Polarization for Flat ...

    Indian Academy of Sciences (India)

    In this paper, using the preliminary database of the University of Michigan Radio Astronomy Observatory (UMRAO) at the radio frequencies, we calculated the weighted polarization at 8 GHz and investigated the correlation between the polarization and the flux density for 92 flat spectrum radio quasars (FSRQs). We found ...

  18. Current density functional theory for optical spectra : A polarization functional

    NARCIS (Netherlands)

    Boeij, P.L. de; Kootstra, F.; Berger, J.A.; Leeuwen, R. van; Snijders, J.G.

    2001-01-01

    In this paper we present a new approach to calculate optical spectra, which for the first time uses a polarization dependent functional within current density functional theory (CDFT), which was proposed by Vignale and Kohn. This polarization dependent functional includes exchange-correlation (xc)

  19. Femoral fracture repair using a locking plate technique in an adult captive polar bear (Ursus maritimus).

    Science.gov (United States)

    Zimmerman, Dawn M; Dew, Terry; Douglass, Michael; Perez, Edward

    2010-02-01

    To report successful femoral fracture repair in a polar bear. Case report. Female polar bear (Ursus maritimus) 5 years and approximately 250 kg. A closed, complete, comminuted fracture of the distal midshaft femur was successfully reduced and stabilized using a compression plating technique with 2 specialized human femur plates offering axial, rotational, and bending support, and allowing the bone to share loads with the implant. Postoperative radiographs were obtained at 11.5 weeks, 11 months, and 24 months. Bone healing characterized by marked periosteal reaction was evident at 11 months with extensive remodeling evident at 24 months. No complications were noted. Distal mid shaft femoral fracture was reduced, stabilized, and healed in an adult polar bear with a locking plate technique using 2 plates. Previously, femoral fractures in polar bears were considered irreparable. Use of 2 plates applied with a locking plate technique can result in successful fracture repair despite large body weight and inability to restrict postoperative activity.

  20. Enlarged clitoris in wild polar bears (Ursus maritimus) can be misdiagnosed as pseudohermaphroditism

    DEFF Research Database (Denmark)

    Sonne, C.; Leifsson, Páll Skuli; Dietz, R.

    2005-01-01

    A 23-year-old female polar bear (Ursus maritimus) killed in an Inuit hunt in East Greenland on July 9, 1999 had a significantly enlarged clitoris resembling, in size, form and colour, those of previously reported 'pseudohermaphroditic' polar bears from Svalbard. It has been suggested that an enzyme...... defect (21-hydroxylase deficiency), androgen producing tumour or high exposure to organochlorines during the foetal stage or early development could be the reason for the supposed pseudohermaphroditism observed for Svalbard bears. Except for the enlarged clitoris, all dimensions of the external...... and internal reproductive organs of the present were similar to a reference group of 23 normal adult female polar bears from East Greenland collected in 1999-2002. The aberrant bear was a female genotype, and macroscopic examination of her internal reproductive organs indicated that she was reproductively...

  1. Molecular density functional theory of water including density-polarization coupling.

    Science.gov (United States)

    Jeanmairet, Guillaume; Levy, Nicolas; Levesque, Maximilien; Borgis, Daniel

    2016-06-22

    We present a three-dimensional molecular density functional theory of water derived from first-principles that relies on the particle's density and multipolar polarization density and includes the density-polarization coupling. This brings two main benefits: (i) scalar density and vectorial multipolar polarization density fields are much more tractable and give more physical insight than the full position and orientation densities, and (ii) it includes the full density-polarization coupling of water, that is known to be non-vanishing but has never been taken into account. Furthermore, the theory requires only the partial charge distribution of a water molecule and three measurable bulk properties, namely the structure factor and the Fourier components of the longitudinal and transverse dielectric susceptibilities.

  2. Is the polar bear (Ursus maritimus) a hibernator? Continued studies on opioids and hibernation.

    Science.gov (United States)

    Bruce, D S; Darling, N K; Seeland, K J; Oeltgen, P R; Nilekani, S P; Amstrup, S C

    1990-03-01

    Polar bear behavior and biochemistry suggest they may have the ability to hibernate year-round, even though this species is not considered to be a true hibernator. This observation, plus the discovery of a hibernation-induction trigger (HIT) in the blood of black bears, prompted the examination of polar bear blood collected throughout the year for evidence of HIT, and to determine if it displayed opioid activity, as black bear blood does. A bioassay was conducted by injecting summer 13-lined ground squirrels with serum collected from polar bears at different seasons. One group of squirrels was previously implanted with osmotic pumps containing naloxone. The rest had pumps containing saline. Squirrels with saline pumps all hibernated significantly more than those with naloxone, except the group receiving blood from a November polar bear, observed to be highly active and hyperphagic. An in vitro study, using guinea pig ileum, showed that 400 nM morphine inhibited induced contractions and 100 nM naloxone reversed the inhibition. Ten mg of winter polar bear serum albumin fraction (to which HIT binds in ground squirrels and woodchucks) had a similar inhibiting effect, but naloxone, even at 4,000 nM, didn't reverse it. It is concluded that polar bear blood contains HIT, that it has an inhibiting effect, but naloxone, even at 4,000 nM, didn't reverse it. It is concluded that polar bear blood contains HIT, that it has an opioid effect, but may not itself be an opioid.

  3. Polychlorinated biphenyls and reproductive hormones in female polar bears at Svalbard.

    OpenAIRE

    Haave, Marte; Ropstad, Erik; Derocher, Andrew E; Lie, Elisabeth; Dahl, Ellen; Wiig, Øystein; Skaare, Janneche U; Jenssen, Bjørn Munro

    2003-01-01

    High concentrations of polychlorinated biphenyls (PCBs) in polar bears from Svalbard have increased concern for that population's reproductive health. We examined whether there were associations between the plasma concentrations of PCBs and reproductive hormones [progesterone (P4)] and 17 beta-estradiol (E2)] in free-living female polar bears from Svalbard. Concentrations of P4 depended on reproductive status, and concentrations were lowest in females with offspring--females with cubs and fem...

  4. The polar bear Ursus maritimus feeding in a seabird colony in Frans Josef Land

    OpenAIRE

    Stempniewicz, Lech

    1993-01-01

    During the second half of August 1992 polar bears were observed feeding intensively in the little auk Alle alle colony on Rubini Rock, Hooker Island, Frans Josef Land. They dug out nests eating eggs, chicks and adult birds. Their activity results in both worsening the breeding conditions and decreasing the breeding success of the little auks. The polar bear has not earlier been known as a little auk predator.

  5. Relative influences of climate change and human activity on the onshore distribution of polar bears

    Science.gov (United States)

    Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Atwood, Todd C.; Peacock, Elizabeth; Miller, Susanne; Divoky, George J.

    2017-01-01

    Climate change is altering habitat for many species, leading to shifts in distributions that can increase levels of human-wildlife conflict. To develop effective strategies for minimizing human-wildlife conflict, we must understand the relative influences that climate change and other factors have on wildlife distributions. Polar bears (Ursus maritimus) are increasingly using land during summer and autumn due to sea ice loss, leading to higher incidents of conflict and concerns for human safety. We sought to understand the relative influence of sea ice conditions, onshore habitat characteristics, and human-provisioned food attractants on the distribution and abundance of polar bears while on shore. We also wanted to determine how mitigation measures might reduce human-polar bear conflict associated with an anthropogenic food source. We built a Bayesian hierarchical model based on 14 years of aerial survey data to estimate the weekly number and distribution of polar bears on the coast of northern Alaska in autumn. We then used the model to predict how effective two management options for handling subsistence-harvested whale remains in the community of Kaktovik, Alaska might be. The distribution of bears on shore was most strongly influenced by the presence of whale carcasses and to a lesser extent sea ice and onshore habitat conditions. The numbers of bears on shore were related to sea ice conditions. The two management strategies for handling the whale carcasses reduced the estimated number of bears near Kaktovik by > 75%. By considering multiple factors associated with the onshore distribution and abundance of polar bears we discerned what role human activities played in where bears occur and how successful efforts to manage the whale carcasses might be for reducing human-polar bear conflict.

  6. Animal physiology. Summer declines in activity and body temperature offer polar bears limited energy savings.

    Science.gov (United States)

    Whiteman, J P; Harlow, H J; Durner, G M; Anderson-Sprecher, R; Albeke, S E; Regehr, E V; Amstrup, S C; Ben-David, M

    2015-07-17

    Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of "ice" bears in summer is unknown, "shore" bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation. Copyright © 2015, American Association for the Advancement of Science.

  7. Summer declines in activity and body temperature offer polar bears limited energy savings

    Science.gov (United States)

    Whiteman, J.P.; Harlow, H.J.; Durner, George M.; Anderson-Sprecher, R.; Albeke, Shannon E.; Regehr, Eric V.; Amstrup, Steven C.; Ben-David, M.

    2015-01-01

    Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of “ice” bears in summer is unknown, “shore” bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation.

  8. Is bone mineral composition disrupted by organochlorines in east Greenland polar bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Born, Erik W

    2004-01-01

    We analyzed bone mineral density (BMD) in skulls of polar bears (Ursus maritimus) (n = 139) from East Greenland sampled during 1892-2002. Our primary goal was to detect possible changes in bone mineral content (osteopenia) due to elevated exposure to organochlorine [polychlorinated biphenyls (PCBs......), dichlorodiphenyl trichloroethane (DDT) and its metabolites, chlordanes (CHLs), dieldrin, hexacyclohexanes, hexachlorobenzene] and polybrominated diphenyl ether (PBDE) compounds. To ensure that the BMD value in skull represented the mineral status of the skeletal system in general, we compared BMD values in femur...... and three lumbar vertebrae with skull in a subsample. We detected highly significant correlations between BMD in skull and femur (r = 0.99; p sampled in the supposed pre-organochlorine/PBDE period (1892...

  9. Identifying polar bear resource selection patterns to inform offshore development in a dynamic and changing Arctic

    Science.gov (United States)

    Wilson, Ryan R.; Horne, Jon S.; Rode, Karyn D.; Regehr, Eric V.; Durner, George M.

    2014-01-01

    Although sea ice loss is the primary threat to polar bears (Ursus maritimus), little can be done to mitigate its effects without global efforts to reduce greenhouse gas emissions. Other factors, however, could exacerbate the impacts of sea ice loss on polar bears, such as exposure to increased industrial activity. The Arctic Ocean has enormous oil and gas potential, and its development is expected to increase in the coming decades. Estimates of polar bear resource selection will inform managers how bears use areas slated for oil development and to help guide conservation planning. We estimated temporally-varying resource selection patterns for non-denning adult female polar bears in the Chukchi Sea population (2008–2012) at two scales (i.e., home range and weekly steps) to identify factors predictive of polar bear use throughout the year, before any offshore development. From the best models at each scale, we estimated scale-integrated resource selection functions to predict polar bear space use across the population's range and determined when bears were most likely to use the region where offshore oil and gas development in the United States is slated to occur. Polar bears exhibited significant intra-annual variation in selection patterns at both scales but the strength and annual patterns of selection differed between scales for most variables. Bears were most likely to use the offshore oil and gas planning area during ice retreat and growth with the highest predicted use occurring in the southern portion of the planning area. The average proportion of predicted high-value habitat in the planning area was >15% of the total high-value habitat for the population during sea ice retreat and growth and reached a high of 50% during November 2010. Our results provide a baseline on which to judge future changes to non-denning adult female polar bear resource selection in the Chukchi Sea and help guide offshore development in the region. Lastly, our study provides a

  10. High contributions of sea ice derived carbon in polar bear (Ursus maritimus) tissue.

    Science.gov (United States)

    Brown, Thomas A; Galicia, Melissa P; Thiemann, Gregory W; Belt, Simon T; Yurkowski, David J; Dyck, Markus G

    2018-01-01

    Polar bears (Ursus maritimus) rely upon Arctic sea ice as a physical habitat. Consequently, conservation assessments of polar bears identify the ongoing reduction in sea ice to represent a significant threat to their survival. However, the additional role of sea ice as a potential, indirect, source of energy to bears has been overlooked. Here we used the highly branched isoprenoid lipid biomarker-based index (H-Print) approach in combination with quantitative fatty acid signature analysis to show that sympagic (sea ice-associated), rather than pelagic, carbon contributions dominated the marine component of polar bear diet (72-100%; 99% CI, n = 55), irrespective of differences in diet composition. The lowest mean estimates of sympagic carbon were found in Baffin Bay bears, which were also exposed to the most rapidly increasing open water season. Therefore, our data illustrate that for future Arctic ecosystems that are likely to be characterised by reduced sea ice cover, polar bears will not only be impacted by a change in their physical habitat, but also potentially in the supply of energy to the ecosystems upon which they depend. This data represents the first quantifiable baseline that is critical for the assessment of likely ongoing changes in energy supply to Arctic predators as we move into an increasingly uncertain future for polar ecosystems.

  11. White-beaked dolphins trapped in the ice and eaten by polar bears

    Directory of Open Access Journals (Sweden)

    Jon Aars

    2015-06-01

    Full Text Available Polar bears (Ursus maritimus depend on sea ice, where they hunt ice-associated seals. However, they are opportunistic predators and scavengers with a long list of known prey species. Here we report from a small fjord in Svalbard, Norwegian High Arctic, a sighting of an adult male polar bear preying on two white-beaked dolphins (Lagenorhynchus albirostris on 23 April 2014. This is the first record of this species as polar bear prey. White-beaked dolphins are frequent visitors to Svalbard waters in summer, but have not previously been reported this far north in early spring. We suggest they were trapped in the ice after strong northerly winds the days before, and possibly killed when forced to surface for air at a small opening in the ice. The bear had consumed most parts of one dolphin. When observed he was in the process of covering the mostly intact second dolphin with snow. Such caching behaviour is generally considered untypical of polar bears. During the following ice-free summer and autumn, at least seven different white-beaked dolphin carcasses were observed in or near the same area. We suggest, based on the area and the degree to which these dolphins had decayed, that they were likely from the same pod and also suffered death due to entrapment in the ice in April. At least six different polar bears were seen scavenging on the carcasses.

  12. Serum corticosteroid binding globulin expression is modulated by fasting in polar bears (Ursus maritimus).

    Science.gov (United States)

    Chow, Brian A; Hamilton, Jason; Cattet, Marc R L; Stenhouse, Gordon; Obbard, Martyn E; Vijayan, Mathilakath M

    2011-01-01

    Polar bears (Ursus maritimus) from several subpopulations undergo extended fasting during the ice-free season. However, the animals appear to conserve protein despite the prolonged fasting, though the mechanisms involved are poorly understood. We hypothesized that elevated concentrations of corticosteroid binding globulin (CBG), the primary cortisol binding protein in circulation, lead to cortisol resistance and provide a mechanism for protein conservation during extended fasting. The metabolic state (feeding vs. fasting) of 16 field sampled male polar bears was determined based on their serum urea to creatinine ratio (>25 for feeding vs. polar bears sampled. Serum CBG expression was greater in lactating females relative to non-lactating females and males. CBG expression was significantly higher in fasting males when compared to non-fasting males. This leads us to suggest that CBG expression may serve as a mechanism to conserve protein during extended fasting in polar bears by reducing systemic free cortisol concentrations. This was further supported by a lower serum glucose concentration in the fasting bears. As well, a lack of an enhanced adrenocortical response to acute capture stress supports our hypothesis that chronic hunger is not a stressor in this species. Overall, our results suggest that elevated serum CBG expression may be an important adaptation to spare proteins by limiting cortisol bioavailability during extended fasting in polar bears. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. High contributions of sea ice derived carbon in polar bear (Ursus maritimus tissue.

    Directory of Open Access Journals (Sweden)

    Thomas A Brown

    Full Text Available Polar bears (Ursus maritimus rely upon Arctic sea ice as a physical habitat. Consequently, conservation assessments of polar bears identify the ongoing reduction in sea ice to represent a significant threat to their survival. However, the additional role of sea ice as a potential, indirect, source of energy to bears has been overlooked. Here we used the highly branched isoprenoid lipid biomarker-based index (H-Print approach in combination with quantitative fatty acid signature analysis to show that sympagic (sea ice-associated, rather than pelagic, carbon contributions dominated the marine component of polar bear diet (72-100%; 99% CI, n = 55, irrespective of differences in diet composition. The lowest mean estimates of sympagic carbon were found in Baffin Bay bears, which were also exposed to the most rapidly increasing open water season. Therefore, our data illustrate that for future Arctic ecosystems that are likely to be characterised by reduced sea ice cover, polar bears will not only be impacted by a change in their physical habitat, but also potentially in the supply of energy to the ecosystems upon which they depend. This data represents the first quantifiable baseline that is critical for the assessment of likely ongoing changes in energy supply to Arctic predators as we move into an increasingly uncertain future for polar ecosystems.

  14. High contributions of sea ice derived carbon in polar bear (Ursus maritimus) tissue

    Science.gov (United States)

    Galicia, Melissa P.; Thiemann, Gregory W.; Belt, Simon T.; Yurkowski, David J.; Dyck, Markus G.

    2018-01-01

    Polar bears (Ursus maritimus) rely upon Arctic sea ice as a physical habitat. Consequently, conservation assessments of polar bears identify the ongoing reduction in sea ice to represent a significant threat to their survival. However, the additional role of sea ice as a potential, indirect, source of energy to bears has been overlooked. Here we used the highly branched isoprenoid lipid biomarker-based index (H-Print) approach in combination with quantitative fatty acid signature analysis to show that sympagic (sea ice-associated), rather than pelagic, carbon contributions dominated the marine component of polar bear diet (72–100%; 99% CI, n = 55), irrespective of differences in diet composition. The lowest mean estimates of sympagic carbon were found in Baffin Bay bears, which were also exposed to the most rapidly increasing open water season. Therefore, our data illustrate that for future Arctic ecosystems that are likely to be characterised by reduced sea ice cover, polar bears will not only be impacted by a change in their physical habitat, but also potentially in the supply of energy to the ecosystems upon which they depend. This data represents the first quantifiable baseline that is critical for the assessment of likely ongoing changes in energy supply to Arctic predators as we move into an increasingly uncertain future for polar ecosystems. PMID:29360849

  15. Ovulation induction and artificial insemination of a captive polar bear (Ursus maritimus) using fresh semen.

    Science.gov (United States)

    Curry, Erin; Wyatt, Jeff; Sorel, Lawrence J; MacKinnon, Katherine M; Roth, Terri L

    2014-09-01

    In 2008, polar bears were listed as a species threatened with extinction by the U.S. Endangered Species Act. Unfortunately, reproductive success has been poor despite breeding recommendations for almost every reproductively viable bear by the Species Survival Plan. Assisted reproductive technologies could complement breeding efforts by overcoming the challenges of behavioral incompatibilities and deficiencies, facilitating genetic management and increasing cub production. The goal of this study was to artificially inseminate a female polar bear after inducing ovarian activity and ovulation with exogenous hormones (equine chorionic gonadotropin and porcine luteinizing hormone). Fresh semen collected from an adult male via electroejaculation/urethral catheterization was used for the insemination. Fecal steroid monitoring indicated that the female ovulated following the exogenous hormone treatment. Progestin concentrations increased in late summer, at the time implantation was expected to occur; however, no cubs were produced. To the authors' knowledge, this is the first report of ovulation induction and artificial insemination in a polar bear.

  16. Acute gastric dilatation and volvulus in a free-living polar bear

    Science.gov (United States)

    Amstrup, Steven C.; Nielsen, Carol A.

    1989-01-01

    A large, adult male polar bear (Ursus maritimus) was found dead on a barrier island north of Prudhoe Bay, Alaska (USA), in June 1987. There were no external signs of trauma. A twisted distended stomach, distinctive parenchymal and fascial congestion, and significant difficulty in repositioning the anterior abdominal organs, indicated that gastric dilatation-volvulus (GDV) was the proximate cause of death. Polar bears frequently consume large quantities of food at one time and have large stomachs that are well adapted to periodic gorging. The scarcity of food in winter and early spring, combined with voluntary fasting and protracted vigorous activity during the breeding season in late spring may have predisposed this bear to GDV. The relationship between GDV and postprandial exercise emphasizes the need for a better understanding of how the present human invasion of arctic habitats may influence polar bear activities.

  17. Temporal Trends and Future Predictions of Mercury Concentrations in Northwest Greenland Polar Bear (Ursus maritimus) Hair

    DEFF Research Database (Denmark)

    Dietz, Rune; Born, E.W.; Riget, Frank Farsø

    2011-01-01

    Hair samples from 117 Northwest Greenland polar bears (Ursus maritimus) were taken during 1892-2008 and analyzed for total mercury (hereafterHg). The sample represented 28 independent years and the aim of the study was to analyze for temporal Hg trends. Mercury concentrations showed yearly...... significant increases of 1.6-1.7% (p bear......-2008 concentrations ofHg in Northwest Greenland polar bear hair exceeded the general guideline values of 20-30 μg/g dry weight for terrestrial wildlife, whereas the neurochemical effect level of 5.4 μg Hg/g dry weight proposed for East Greenland polar bears was exceeded in 93.5% of the cases. These results call...

  18. Xenoestrogenic and dioxin-like activity in blood of East Greenland polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Erdmann, Simon Erik; Dietz, Rune; Sonne, Christian

    2013-01-01

    The aims of the project were to (i) extract the lipophilic persistent organic pollutants (POPs) from the blood of 99 East Greenland polar bears and assess the combined mixture effect on the estrogen receptor (ER) and the aryl hydrocarbon receptor (AhR) mediated transactivity; (ii) To evaluate...... whether the receptor transactivities were associated with selected POP markers, and (iii) compare the receptor transactivities in polar bears with earlier studies on Greenlandic Inuit. Lipophilic POPs were extracted using a combination of solid-phase extraction (SPE) and high performance liquid...... induced ER response. Positive correlations were found in subadult bears between XER and several POP biomarkers. XER and XERcomp correlated positively to each other. A total of 91% of the polar bear blood extracts elicited agonistic AhR transactivity. The AhR-TCDD equivalent (AhR-TEQ) median levels were...

  19. A retrospective study of end-stage renal disease in captive polar bears (Ursus maritimus).

    Science.gov (United States)

    LaDouceur, Elise E B; Davis, Barbara; Tseng, Flo

    2014-03-01

    This retrospective study summarizes 11 cases of end-stage renal disease (ESRD) in captive polar bears (Ursus maritimus) from eight zoologic institutions across the United States and Canada. Ten bears were female, one was male, and the mean age at the time of death was 24 yr old. The most common clinical signs were lethargy, inappetence, and polyuria-polydipsia. Biochemical findings included azotemia, anemia, hyperphosphatemia, and isosthenuria. Histologic examination commonly showed glomerulonephropathies and interstitial fibrosis. Based on submissions to a private diagnostic institution over a 16-yr period, ESRD was the most commonly diagnosed cause of death or euthanasia in captive polar bears in the United States, with an estimated prevalence of over 20%. Further research is needed to discern the etiology of this apparently common disease of captive polar bears.

  20. Human-polar bear interactions in a changing Arctic: Existing and emerging concerns

    Science.gov (United States)

    Atwood, Todd C.; Simac, Kristin; Breck, Stewart; York, Geoff; Wilder, James

    2017-01-01

    The behavior and sociality of polar bears (Ursus maritimus) have been shaped by evolved preferences for sea ice habitat and preying on marine mammals. However, human behavior is causing changes to the Arctic marine ecosystem through the influence of greenhouse gas emissions that drive long-term change in ecosystem processes and via the presence of in situ stressors associated with increasing human activities. These changes are making it more difficult for polar bears to reliably use their traditional habitats and maintain fitness. Here, we provide an overview of how human activities in the Arctic are likely to change a polar bear’s behavior and to influence their resilience to environmental change. Developing a more thorough understanding of polar bear behavior and their capacity for flexibility in response to anthropogenic disturbances and subsequent mitigations may lead to successful near-term management interventions.

  1. Spin polarization in high density quark matter

    DEFF Research Database (Denmark)

    Bohr, Henrik; Panda, Prafulla K.; Providênci, Constanca

    2013-01-01

    We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu-Jona-Lasinio model...... the so-called 2 flavor super-conducting phase to the ferromagnetic phase arises. The color-flavor-locked phase may be completely hidden by the FP....

  2. Potential impacts of offshore oil spills on polar bears in the Chukchi Sea.

    Science.gov (United States)

    Wilson, Ryan R; Perham, Craig; French-McCay, Deborah P; Balouskus, Richard

    2018-04-01

    Sea ice decline is anticipated to increase human access to the Arctic Ocean allowing for offshore oil and gas development in once inaccessible areas. Given the potential negative consequences of an oil spill on marine wildlife populations in the Arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. In this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two sites in the Chukchi Sea (one in Russia and one in the U.S.) and tracked the distribution of oil for 76 days. We then determined the potential impact such a spill might have on polar bears (Ursus maritimus) and their habitat by overlapping spills with maps of polar bear habitat and movement trajectories. Only a small proportion (1-10%) of high-value polar bear sea ice habitat was directly affected by oil sufficient to impact bears. However, 27-38% of polar bears in the region were potentially exposed to oil. Oil consistently had the highest probability of reaching Wrangel and Herald islands, important areas of denning and summer terrestrial habitat. Oil did not reach polar bears until approximately 3 weeks after the spills. Our study found the potential for significant impacts to polar bears under a worst case discharge scenario, but suggests that there is a window of time where effective containment efforts could minimize exposure to bears. Our study provides a framework for wildlife managers and planners to assess the level of response that would be required to treat exposed wildlife and where spill response equipment might be best stationed. While the size of spill we simulated has a low probability of occurring, it provides an upper limit for planners to consider when crafting response plans. Published by Elsevier Ltd.

  3. Age and sex composition of seals killed by polar bears in the eastern Beaufort Sea.

    Directory of Open Access Journals (Sweden)

    Nicholas W Pilfold

    Full Text Available BACKGROUND: Polar bears (Ursus maritimus of the Beaufort Sea enter hyperphagia in spring and gain fat reserves to survive periods of low prey availability. We collected information on seals killed by polar bears (n=650 and hunting attempts on ringed seal (Pusa hispida lairs (n=1396 observed from a helicopter during polar bear mark-recapture studies in the eastern Beaufort Sea in spring in 1985-2011. We investigated how temporal shifts in ringed seal reproduction affect kill composition and the intraspecific vulnerabilities of ringed seals to polar bear predation. PRINCIPAL FINDINGS: Polar bears primarily preyed on ringed seals (90.2% while bearded seals (Erignathus barbatus only comprised 9.8% of the kills, but 33% of the biomass. Adults comprised 43.6% (150/344 of the ringed seals killed, while their pups comprised 38.4% (132/344. Juvenile ringed seals were killed at the lowest proportion, comprising 18.0% (62/344 of the ringed seal kills. The proportion of ringed seal pups was highest between 2007-2011, in association with high ringed seal productivity. Half of the adult ringed seal kills were ≥ 21 years (60/121, and kill rates of adults increased following the peak of parturition. Determination of sex from DNA revealed that polar bears killed adult male and adult female ringed seals equally (0.50, n=78. The number of hunting attempts at ringed seal subnivean lair sites was positively correlated with the number of pup kills (r(2 =0.30, P=0.04, but was not correlated with the number of adult kills (P=0.37. CONCLUSIONS/SIGNIFICANCE: Results are consistent with decadal trends in ringed seal productivity, with low numbers of pups killed by polar bears in spring in years of low pup productivity, and conversely when pup productivity was high. Vulnerability of adult ringed seals to predation increased in relation to reproductive activities and age, but not gender.

  4. Age and sex composition of seals killed by polar bears in the eastern Beaufort Sea.

    Science.gov (United States)

    Pilfold, Nicholas W; Derocher, Andrew E; Stirling, Ian; Richardson, Evan; Andriashek, Dennis

    2012-01-01

    Polar bears (Ursus maritimus) of the Beaufort Sea enter hyperphagia in spring and gain fat reserves to survive periods of low prey availability. We collected information on seals killed by polar bears (n=650) and hunting attempts on ringed seal (Pusa hispida) lairs (n=1396) observed from a helicopter during polar bear mark-recapture studies in the eastern Beaufort Sea in spring in 1985-2011. We investigated how temporal shifts in ringed seal reproduction affect kill composition and the intraspecific vulnerabilities of ringed seals to polar bear predation. Polar bears primarily preyed on ringed seals (90.2%) while bearded seals (Erignathus barbatus) only comprised 9.8% of the kills, but 33% of the biomass. Adults comprised 43.6% (150/344) of the ringed seals killed, while their pups comprised 38.4% (132/344). Juvenile ringed seals were killed at the lowest proportion, comprising 18.0% (62/344) of the ringed seal kills. The proportion of ringed seal pups was highest between 2007-2011, in association with high ringed seal productivity. Half of the adult ringed seal kills were ≥ 21 years (60/121), and kill rates of adults increased following the peak of parturition. Determination of sex from DNA revealed that polar bears killed adult male and adult female ringed seals equally (0.50, n=78). The number of hunting attempts at ringed seal subnivean lair sites was positively correlated with the number of pup kills (r(2) =0.30, P=0.04), but was not correlated with the number of adult kills (P=0.37). Results are consistent with decadal trends in ringed seal productivity, with low numbers of pups killed by polar bears in spring in years of low pup productivity, and conversely when pup productivity was high. Vulnerability of adult ringed seals to predation increased in relation to reproductive activities and age, but not gender.

  5. Use of hyaluronidase to improve chemical immobilization of free-ranging polar bears (Ursus maritimus).

    Science.gov (United States)

    Cattet, Marc R L; Obbard, Martyn E

    2010-01-01

    We assessed the efficacy and safety of hyaluronidase to improve chemical immobilization of free-ranging polar bears (Ursus maritimus) captured from helicopter by remote drug delivery along the Ontario coast line of northwestern James Bay and southern Hudson Bay during September 2005 and October 2007. We used a single blind study design in which one person prepared and loaded all darts without the shooter knowing whether hyaluronidase (150 IU per dart) or sterile water was added to the immobilizing drug mixture of xylazine and zolazepam-tiletamine (XZT). We found that we often required more than one dart to immobilize bears in the control group (XZT+sterile water; >1 dart for 15 of 28 captures) versus the treatment group (XZT+hyaluronidase; >1 dart for seven of 26 captures). As a consequence, treatment bears were generally immobilized with smaller XZT dosages (7.9 vs. 9.4 mg/kg; P = 0.08) and shorter induction (10 vs. 15 min; P = 0.004) than control bears. We found no differences in vital rates and serum biochemistry results between control and treatment bears. We did find, however, that induction times correlated directly with rectal temperature at bears. Overall we found hyaluronidase to be effective and safe for capture of polar bears. We recommend further study to determine whether effects of hyaluronidase are dose dependent and recommend that others involved with capture of seasonally fat species such as polar bears consider use of hyaluronidase to improve chemical immobilization.

  6. Field metabolic rate and PCB adipose tissue deposition efficiency in East Greenland polar bears derived from contaminant monitoring data.

    Science.gov (United States)

    Pavlova, Viola; Nabe-Nielsen, Jacob; Dietz, Rune; Svenning, Jens-Christian; Vorkamp, Katrin; Rigét, Frank Farsø; Sonne, Christian; Letcher, Robert J; Grimm, Volker

    2014-01-01

    Climate change will increasingly affect the natural habitat and diet of polar bears (Ursus maritimus). Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB) congener, 2,2',4,4',55-hexaCB (CB153) in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR) and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.

  7. Field metabolic rate and PCB adipose tissue deposition efficiency in East Greenland polar bears derived from contaminant monitoring data.

    Directory of Open Access Journals (Sweden)

    Viola Pavlova

    Full Text Available Climate change will increasingly affect the natural habitat and diet of polar bears (Ursus maritimus. Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB congener, 2,2',4,4',55-hexaCB (CB153 in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.

  8. Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice

    Science.gov (United States)

    Regehr, E.V.; Hunter, C.M.; Caswell, H.; Amstrup, Steven C.; Stirling, I.

    2010-01-01

    1. Observed and predicted declines in Arctic sea ice have raised concerns about marine mammals. In May 2008, the US Fish and Wildlife Service listed polar bears (Ursus maritimus) - one of the most ice-dependent marine mammals - as threatened under the US Endangered Species Act. 2. We evaluated the effects of sea ice conditions on vital rates (survival and breeding probabilities) for polar bears in the southern Beaufort Sea. Although sea ice declines in this and other regions of the polar basin have been among the greatest in the Arctic, to date population-level effects of sea ice loss on polar bears have only been identified in western Hudson Bay, near the southern limit of the species' range. 3. We estimated vital rates using multistate capture-recapture models that classified individuals by sex, age and reproductive category. We used multimodel inference to evaluate a range of statistical models, all of which were structurally based on the polar bear life cycle. We estimated parameters by model averaging, and developed a parametric bootstrap procedure to quantify parameter uncertainty. 4. In the most supported models, polar bear survival declined with an increasing number of days per year that waters over the continental shelf were ice free. In 2001-2003, the ice-free period was relatively short (mean 101 days) and adult female survival was high (0 ∙ 96-0 ∙ 99, depending on reproductive state). In 2004 and 2005, the ice-free period was longer (mean 135 days) and adult female survival was low (0 ∙ 73-0 ∙ 79, depending on reproductive state). Breeding rates and cub litter survival also declined with increasing duration of the ice-free period. Confidence intervals on vital rate estimates were wide. 5. The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines. Our findings

  9. Survival and breeding of polar bears in the southern Beaufort Sea in relation to sea ice.

    Science.gov (United States)

    Regehr, Eric V; Hunter, Christine M; Caswell, Hal; Amstrup, Steven C; Stirling, Ian

    2010-01-01

    1. Observed and predicted declines in Arctic sea ice have raised concerns about marine mammals. In May 2008, the US Fish and Wildlife Service listed polar bears (Ursus maritimus) - one of the most ice-dependent marine mammals - as threatened under the US Endangered Species Act. 2. We evaluated the effects of sea ice conditions on vital rates (survival and breeding probabilities) for polar bears in the southern Beaufort Sea. Although sea ice declines in this and other regions of the polar basin have been among the greatest in the Arctic, to date population-level effects of sea ice loss on polar bears have only been identified in western Hudson Bay, near the southern limit of the species' range. 3. We estimated vital rates using multistate capture-recapture models that classified individuals by sex, age and reproductive category. We used multimodel inference to evaluate a range of statistical models, all of which were structurally based on the polar bear life cycle. We estimated parameters by model averaging, and developed a parametric bootstrap procedure to quantify parameter uncertainty. 4. In the most supported models, polar bear survival declined with an increasing number of days per year that waters over the continental shelf were ice free. In 2001-2003, the ice-free period was relatively short (mean 101 days) and adult female survival was high (0.96-0.99, depending on reproductive state). In 2004 and 2005, the ice-free period was longer (mean 135 days) and adult female survival was low (0.73-0.79, depending on reproductive state). Breeding rates and cub litter survival also declined with increasing duration of the ice-free period. Confidence intervals on vital rate estimates were wide. 5. The effects of sea ice loss on polar bears in the southern Beaufort Sea may apply to polar bear populations in other portions of the polar basin that have similar sea ice dynamics and have experienced similar, or more severe, sea ice declines. Our findings therefore are

  10. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines.

    Science.gov (United States)

    Regehr, Eric V; Laidre, Kristin L; Akçakaya, H Resit; Amstrup, Steven C; Atwood, Todd C; Lunn, Nicholas J; Obbard, Martyn; Stern, Harry; Thiemann, Gregory W; Wiig, Øystein

    2016-12-01

    Loss of Arctic sea ice owing to climate change is the primary threat to polar bears throughout their range. We evaluated the potential response of polar bears to sea-ice declines by (i) calculating generation length (GL) for the species, which determines the timeframe for conservation assessments; (ii) developing a standardized sea-ice metric representing important habitat; and (iii) using statistical models and computer simulation to project changes in the global population under three approaches relating polar bear abundance to sea ice. Mean GL was 11.5 years. Ice-covered days declined in all subpopulation areas during 1979-2014 (median -1.26 days year -1 ). The estimated probabilities that reductions in the mean global population size of polar bears will be greater than 30%, 50% and 80% over three generations (35-41 years) were 0.71 (range 0.20-0.95), 0.07 (range 0-0.35) and less than 0.01 (range 0-0.02), respectively. According to IUCN Red List reduction thresholds, which provide a common measure of extinction risk across taxa, these results are consistent with listing the species as vulnerable. Our findings support the potential for large declines in polar bear numbers owing to sea-ice loss, and highlight near-term uncertainty in statistical projections as well as the sensitivity of projections to different plausible assumptions. © 2016 The Authors.

  11. Anthropogenic flank attack on polar bears: Interacting consequences of climate warming and pollutant exposure

    Directory of Open Access Journals (Sweden)

    Bjørn Munro Jenssen

    2015-02-01

    Full Text Available Polar bears (Ursus maritimus are subjected to several anthropogenic threats, climate warming and exposure to pollutants being two of these. For polar bears, one of the main effects of climate warming is limited access to prey, due to loss of their sea ice habitat. This will result in prolonged fasting periods and emaciation and condition related negative effects on survival and reproduction success. Prolonged fasting will result in increases of the tissue concentrations of persistent organic pollutants (POPs in polar bears, and thus increase the probability for POP levels to exceed threshold levels for effects on health, and thus on reproductive success and survival. There are clear potentials for interactions between impacts of climate warming and impacts of pollutant exposure on polar bears. It is likely that that fasting-induced increases of POPs will add to mortality rates and decrease reproductive success beyond effects caused by loss of habitat alone. However, there is a lack of studies that have addressed this. Thus, there is a need to focus on population effects of POP exposure in polar bears, and to consider such effects in relation to the effects of climate induced habitat loss.

  12. Polar bear maternal den habitat in the Arctic National Wildlife Refuge, Alaska

    Science.gov (United States)

    Durner, George M.; Amstrup, Steven C.; Ambrosius, Ken J.

    2006-01-01

    Polar bears (Ursus maritimus) give birth during mid-winter in dens of ice and snow. Denning polar bears subjected to human disturbances may abandon dens before their altricial young can survive the rigors of the Arctic winter. Because the Arctic coastal plain of Alaska is an area of high petroleum potential and contains existing and planned oil field developments, the distribution of polar bear dens on the plain is of interest to land managers. Therefore, as part of a study of denning habitats along the entire Arctic coast of Alaska, we examined high-resolution aerial photographs (n = 1655) of the 7994 km2 coastal plain included in the Arctic National Wildlife Refuge (ANWR) and mapped 3621 km of bank habitat suitable for denning by polar bears. Such habitats were distributed uniformly and comprised 0.29% (23.2 km2) of the coastal plain between the Canning River and the Canadian border. Ground-truth sampling suggested that we had correctly identified 91.5% of bank denning habitats on the ANWR coastal plain. Knowledge of the distribution of these habitats will help facilitate informed management of human activities and minimize disruption of polar bears in maternal dens.

  13. Mercury speciation in brain tissue of polar bears (Ursus maritimus) from the Canadian Arctic.

    Science.gov (United States)

    Krey, Anke; Kwan, Michael; Chan, Hing Man

    2012-04-01

    Methylmercury (MeHg) is a neurotoxicant that has been found at elevated concentrations in the Arctic ecosystem. Little is known about its internal dose in wildlife such as polar bears. We measured concentrations of mercury (Hg) in three different brain regions (cerebellum, frontal lobe and brain stem) of 24 polar bears collected from the Nunavik, Canada between 2000 and 2003. Speciation of Hg was measured by High Performance Liquid Chromatography coupled to Inductively Coupled Plasma Mass Spectroscopy (HPLC-ICP-MS). Concentrations of mean total Hg in brain tissue were up to 625 times lower (0.28 ± 0.07 mg kg(-1) dry weight (dw) in frontal lobe, 0.23 ± 0.07 mg kg(-1) dw in cerebellum and 0.12 ± 0.0 3mg kg(-1) dw in brain stem) than the mean total Hg concentration previously reported in polar bear liver collected from Eastern Baffin Island. Methylmercury (MeHg) accounted for 100% of the Hg found in all three brain regions analyzed. These results suggest that polar bear might reduce the toxic effects of Hg by limiting the uptake into the brain and/or decrease the rate of demethylation so that Hg can be excreted from the brain more easily. The toxicokinetics and the blood-brain-barrier mechanisms of polar bears are still unknown and further research is required. Copyright © 2012 Elsevier Inc. All rights reserved.

  14. Invariant polar bear habitat selection during a period of sea ice loss

    Science.gov (United States)

    Wilson, Ryan R.; Regehr, Eric V.; Rode, Karyn D.; St Martin, Michelle

    2016-01-01

    Climate change is expected to alter many species' habitat. A species' ability to adjust to these changes is partially determined by their ability to adjust habitat selection preferences to new environmental conditions. Sea ice loss has forced polar bears (Ursus maritimus) to spend longer periods annually over less productive waters, which may be a primary driver of population declines. A negative population response to greater time spent over less productive water implies, however, that prey are not also shifting their space use in response to sea ice loss. We show that polar bear habitat selection in the Chukchi Sea has not changed between periods before and after significant sea ice loss, leading to a 75% reduction of highly selected habitat in summer. Summer was the only period with loss of highly selected habitat, supporting the contention that summer will be a critical period for polar bears as sea ice loss continues. Our results indicate that bears are either unable to shift selection patterns to reflect new prey use patterns or that there has not been a shift towards polar basin waters becoming more productive for prey. Continued sea ice loss is likely to further reduce habitat with population-level consequences for polar bears.

  15. Increased Arctic sea ice drift alters adult female polar bear movements and energetics.

    Science.gov (United States)

    Durner, George M; Douglas, David C; Albeke, Shannon E; Whiteman, John P; Amstrup, Steven C; Richardson, Evan; Wilson, Ryan R; Ben-David, Merav

    2017-09-01

    Recent reductions in thickness and extent have increased drift rates of Arctic sea ice. Increased ice drift could significantly affect the movements and the energy balance of polar bears (Ursus maritimus) which forage, nearly exclusively, on this substrate. We used radio-tracking and ice drift data to quantify the influence of increased drift on bear movements, and we modeled the consequences for energy demands of adult females in the Beaufort and Chukchi seas during two periods with different sea ice characteristics. Westward and northward drift of the sea ice used by polar bears in both regions increased between 1987-1998 and 1999-2013. To remain within their home ranges, polar bears responded to the higher westward ice drift with greater eastward movements, while their movements north in the spring and south in fall were frequently aided by ice motion. To compensate for more rapid westward ice drift in recent years, polar bears covered greater daily distances either by increasing their time spent active (7.6%-9.6%) or by increasing their travel speed (8.5%-8.9%). This increased their calculated annual energy expenditure by 1.8%-3.6% (depending on region and reproductive status), a cost that could be met by capturing an additional 1-3 seals/year. Polar bears selected similar habitats in both periods, indicating that faster drift did not alter habitat preferences. Compounding reduced foraging opportunities that result from habitat loss; changes in ice drift, and associated activity increases, likely exacerbate the physiological stress experienced by polar bears in a warming Arctic. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  16. A Review of Infectious Agents in Polar Bears (Ursus maritimus) and Their Long-Term Ecological Relevance.

    Science.gov (United States)

    Fagre, Anna C; Patyk, Kelly A; Nol, Pauline; Atwood, Todd; Hueffer, Karsten; Duncan, Colleen

    2015-09-01

    Disease was a listing criterion for the polar bear (Ursus maritimus) as threatened under the Endangered Species Act in 2008; it is therefore important to evaluate the current state of knowledge and identify any information gaps pertaining to diseases in polar bears. We conducted a systematic literature review focused on infectious agents and associated health impacts identified in polar bears. Overall, the majority of reports in free-ranging bears concerned serosurveys or fecal examinations with little to no information on associated health effects. In contrast, most reports documenting illness or pathology referenced captive animals and diseases caused by etiologic agents not representative of exposure opportunities in wild bears. As such, most of the available infectious disease literature has limited utility as a basis for development of future health assessment and management plans. Given that ecological change is a considerable risk facing polar bear populations, future work should focus on cumulative effects of multiple stressors that could impact polar bear population dynamics.

  17. Estimating the abundance of the Southern Hudson Bay polar bear subpopulation with aerial surveys

    Science.gov (United States)

    Obbard, Martyn E.; Stapleton, Seth P.; Middel, Kevin R.; Thibault, Isabelle; Brodeur, Vincent; Jutras, Charles

    2015-01-01

    The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture–recapture studies indicate abundance was likely unchanged between 1986 and 2005, declines in body condition and survival occurred during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted a comprehensive line transect aerial survey of SH during 2011–2012. We stratified the study site by anticipated densities and flew coastal contour transects and systematically spaced inland transects in Ontario and on Akimiski Island and large offshore islands in 2011. Data were collected with double-observer and distance sampling protocols. We surveyed small islands in James Bay and eastern Hudson Bay and flew a comprehensive transect along the Québec coastline in 2012. We observed 667 bears in Ontario and on Akimiski Island and nearby islands in 2011, and we sighted 80 bears on offshore islands during 2012. Mark–recapture distance sampling and sight–resight models yielded an estimate of 860 (SE = 174) for the 2011 study area. Our estimate of abundance for the entire SH subpopulation (943; SE = 174) suggests that abundance is unlikely to have changed significantly since 1986. However, this result should be interpreted cautiously because of the methodological differences between historical studies (physical capture–recapture) and this survey. A conservative management approach is warranted given previous increases in duration of the ice-free season, which are predicted to continue in the future, and previously documented declines in body condition and vital rates.

  18. Estimating abundance of the Southern Hudson Bay polar bear subpopulation using aerial surveys, 2011 and 2012

    Science.gov (United States)

    Obbard, Martyn E.; Middel, Kevin R.; Stapleton, Seth P.; Thibault, Isabelle; Brodeur, Vincent; Jutras, Charles

    2013-01-01

    The Southern Hudson Bay (SH) polar bear subpopulation occurs at the southern extent of the species’ range. Although capture-recapture studies indicate that abundance remained stable between 1986 and 2005, declines in body condition and survival were documented during the period, possibly foreshadowing a future decrease in abundance. To obtain a current estimate of abundance, we conducted a comprehensive line transect aerial survey of SH during 2011–2012. We stratified the study site by anticipated densities and flew coastal contour transects and systematically spaced inland transects in Ontario and on Akimiski Island and large offshore islands in 2011. Data were collected with double observer and distance sampling protocols. We also surveyed small islands in Hudson Bay and James Bay and flew a comprehensive transect along the Québec coastline in 2012. We observed 667 bears in Ontario and on Akimiski Island and nearby islands in 2011, and we sighted 80 bears on offshore islands during 2012. Mark-recapture distance sampling and sightresight models yielded a model-averaged estimate of 868 (SE: 177) for the 2011 study area. Our estimate of abundance for the entire SH subpopulation (951; SE: 177) suggests that abundance has remained unchanged. However, this result should be interpreted cautiously because of the methodological differences between historical studies (physical capture) and this survey. A conservative management approach is warranted given the previous increases in the duration of the ice-free season, which are predicted to continue in the future, and previously documented declines in body condition and vital rates.

  19. Development of a pan-Arctic monitoring plan for polar bears: Background paper

    Science.gov (United States)

    Vongraven, Dag; Peacock, Lily

    2011-01-01

    Polar bears (Ursus maritimus), by their very nature, and the extreme, remote environment in which they live, are inherently difficult to study and monitor. Monitoring polar bear populations is both arduous and costly and, to be effective, must be a long-term commitment. There are few jurisdictional governments and management boards with a mandate for polar bear research and management, and many have limited resources. Although population monitoring of polar bears has been a focus to some degree within most jurisdictions around the Arctic, of the 19 subpopulations recognised by the IUCN/Species Survival Commission Polar Bear Specialist Group (PBSG), adequate scientific trend data exist for only three of the subpopulations, fair trend data for five and poor or no trend data for the remaining 11 subpopulations (PBSG 2010a). There are especially critical knowledge gaps for the subpopulations in East Greenland, in the Russian Kara and Laptev seas, and in the Chukchi Sea, which is shared between Russia and the United States. The range covered by these subpopulations represents a third of the total area (approx. 23 million km2) of polar bears’ current range, and more than half if the Arctic Basin is included. If we use popular terms, we know close to nothing about polar bears in this portion of their range.As summer sea-ice extent, and to a lesser degree, spring-time extent, continues to retreat, outpacing model forecasts (Stroeve et al. 2007, Pedersen et al. 2009), polar bears face the challenge of adapting to rapidly changing habitats. There is a need to use current and synthesised information across the Arctic, and to develop new methods that will facilitate monitoring to generate new knowledge at a pan-Arctic scale. The circumpolar dimension can be lost when efforts are channelled into regional monitoring. Developing and implementing a plan that harmonises local, regional and global efforts will increase our power to detect and understand important trends for polar

  20. Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change

    Science.gov (United States)

    Miller, Webb; Schuster, Stephan C.; Welch, Andreanna J.; Ratan, Aakrosh; Bedoya-Reina, Oscar C.; Zhao, Fangqing; Kim, Hie Lim; Burhans, Richard C.; Drautz, Daniela I.; Wittekindt, Nicola E.; Tomsho, Lynn P.; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Peacock, Elizabeth; Farley, Sean; Sage, George K.; Rode, Karyn D.; Obbard, Martyn E.; Montiel, Rafael; Bachmann, Lutz; Ingólfsson, Ólafur; Aars, Jon; Mailund, Thomas; Wiig, Øystein; Talbot, Sandra L.; Lindqvist, Charlotte

    2012-01-01

    Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. However, for the enigmatic brown bears native to Alaska's Alexander Archipelago, we estimate that not only their mitochondrial genome, but also 5–10% of their nuclear genome, is most closely related to PBs, indicating ancient admixture between the two species. Explicit admixture analyses are consistent with ancient splits among PBs, brown bears and black bears that were later followed by occasional admixture. We also provide paleodemographic estimates that suggest bear evolution has tracked key climate events, and that PB in particular experienced a prolonged and dramatic decline in its effective population size during the last ca. 500,000 years. We demonstrate that brown bears and PBs have had sufficiently independent evolutionary histories over the last 4–5 million years to leave imprints in the PB nuclear genome that likely are associated with ecological adaptation to the Arctic environment.

  1. Polar and brown bear genomes reveal ancient admixture and demographic footprints of past climate change.

    Science.gov (United States)

    Miller, Webb; Schuster, Stephan C; Welch, Andreanna J; Ratan, Aakrosh; Bedoya-Reina, Oscar C; Zhao, Fangqing; Kim, Hie Lim; Burhans, Richard C; Drautz, Daniela I; Wittekindt, Nicola E; Tomsho, Lynn P; Ibarra-Laclette, Enrique; Herrera-Estrella, Luis; Peacock, Elizabeth; Farley, Sean; Sage, George K; Rode, Karyn; Obbard, Martyn; Montiel, Rafael; Bachmann, Lutz; Ingólfsson, Olafur; Aars, Jon; Mailund, Thomas; Wiig, Oystein; Talbot, Sandra L; Lindqvist, Charlotte

    2012-09-04

    Polar bears (PBs) are superbly adapted to the extreme Arctic environment and have become emblematic of the threat to biodiversity from global climate change. Their divergence from the lower-latitude brown bear provides a textbook example of rapid evolution of distinct phenotypes. However, limited mitochondrial and nuclear DNA evidence conflicts in the timing of PB origin as well as placement of the species within versus sister to the brown bear lineage. We gathered extensive genomic sequence data from contemporary polar, brown, and American black bear samples, in addition to a 130,000- to 110,000-y old PB, to examine this problem from a genome-wide perspective. Nuclear DNA markers reflect a species tree consistent with expectation, showing polar and brown bears to be sister species. However, for the enigmatic brown bears native to Alaska's Alexander Archipelago, we estimate that not only their mitochondrial genome, but also 5-10% of their nuclear genome, is most closely related to PBs, indicating ancient admixture between the two species. Explicit admixture analyses are consistent with ancient splits among PBs, brown bears and black bears that were later followed by occasional admixture. We also provide paleodemographic estimates that suggest bear evolution has tracked key climate events, and that PB in particular experienced a prolonged and dramatic decline in its effective population size during the last ca. 500,000 years. We demonstrate that brown bears and PBs have had sufficiently independent evolutionary histories over the last 4-5 million years to leave imprints in the PB nuclear genome that likely are associated with ecological adaptation to the Arctic environment.

  2. Prevalence of antibodies against Toxoplasma gondii in polar bears (Ursus maritimus) from Svalbard and East Greenland.

    Science.gov (United States)

    Oksanen, A; Asbakk, K; Prestrud, K W; Aars, J; Derocher, A E; Tryland, M; Wiig, O; Dubey, J P; Sonne, C; Dietz, R; Andersen, M; Born, E W

    2009-02-01

    Serum samples from 419 polar bears (Ursus maritimus) from Svalbard and the Barents Sea (collected 1990-2000) and 108 polar bears from East Greenland (collected 1999-2004) were assayed for antibodies against Toxoplasma gondii using the modified agglutination test. Antibody prevalences were 3.6% among cubs dependent on their mothers and 21.4% among subadults and adults. Among subadults and adults there was an interaction between population and sex, with similar prevalences among females (Svalbard = 19.5%, Greenland = 18.0%), but a high frequency among Svalbard males (28.7%) as compared to Greenland males (5.8%). The pattern was also significant after correcting for differences in age distribution. The sex-population interaction term is believed to be connected to area- and sex-specific feeding ecology. The prevalences of antibodies against T. gondii in Svalbard and Greenland were high compared to previously reported findings in polar bears from Russian and Alaskan areas.

  3. Hydroxylated polychlorinated biphenyls decrease circulating steroids in female polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Gustavson, Lisa; Ciesielski, Tomasz M.; Bytingsvik, Jenny

    2015-01-01

    As a top predator in the Arctic food chain, polar bears (Ursus maritimus) are exposed to high levels of persistent organic pollutants (POPs). Because several of these compounds have been reported to alter endocrine pathways, such as the steroidogenesis, potential disruption of the sex steroid...... synthesis by POPs may cause implications for reproduction by interfering with ovulation, implantation and fertility. Blood samples were collected from 15 female polar bears in Svalbard (Norway) in April 2008. The concentrations of nine circulating steroid hormones; dehydroepiandrosterone (DHEA......-metabolites (hydroxylated PCBs [OH-PCBs] and hydroxylated PBDEs [OH-PBDEs]), steroid hormones, biological and capture variables in female polar bears. Inverse correlations were found between circulating levels of PRE and AN, and circulating levels of OH-PCBs. There were no significant relationships between the steroid...

  4. Relationships between POPs, biometrics and circulating steroids in male polar bears (Ursus maritimus) from Svalbard

    DEFF Research Database (Denmark)

    Ciesielski, Tomasz M; Hansen, Ingunn Tjelta; Bytingsvik, Jenny

    2017-01-01

    The aim of this study was to determine the effects of persistent organic pollutants (POPs) and biometric variables on circulating levels of steroid hormones (androgens, estrogens and progestagens) in male polar bears (Ursus maritimus) from Svalbard, Norway (n = 23). Levels of pregnenolone (PRE......), progesterone (PRO), androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in polar bear serum by gas chromatography tandem mass spectrometry (GC-MS/MS), while POPs were measured in plasma.......57-12.4 for subadults, 1.02-83.7 for adults), 0.09-2.69 and 0.57-2.44 nmol/L, respectively. The steroid profiles suggest that sex steroids were mainly synthesized through the Δ-4 pathway in male polar bears. The ratio between androgens and estrogens significantly depended on sexual maturity with androgen...

  5. Polar bear and walrus response to the rapid decline in Arctic sea ice

    Science.gov (United States)

    Oakley, K.; Whalen, M.; Douglas, D.; Udevitz, Mark S.; Atwood, Todd C.; Jay, C.

    2012-01-01

    The Arctic is warming faster than other regions of the world due to positive climate feedbacks associated with loss of snow and ice. One highly visible consequence has been a rapid decline in Arctic sea ice over the past 3 decades - a decline projected to continue and result in ice-free summers likely as soon as 2030. The polar bear (Ursus maritimus) and the Pacific walrus (Odobenus rosmarus divergens) are dependent on sea ice over the continental shelves of the Arctic Ocean's marginal seas. The continental shelves are shallow regions with high biological productivity, supporting abundant marine life within the water column and on the sea floor. Polar bears use sea ice as a platform for hunting ice seals; walruses use sea ice as a resting platform between dives to forage for clams and other bottom-dwelling invertebrates. How have sea ice changes affected polar bears and walruses? How will anticipated changes affect them in the future?

  6. Polar bears (Ursus maritimus mating during late June on the pack ice of northern Svalbard, Norway

    Directory of Open Access Journals (Sweden)

    Thomas G. Smith

    2015-03-01

    Full Text Available Polar bears are seasonal breeders and typically mate from late March to early May. Implantation is, however, delayed until autumn, which can allow plasticity in the date of mating. As for other seasonal breeders, a rapid return to estrus after the loss of dependent offspring can be expected, even into the summer. A few earlier observations and dissections of dead animals suggest that polar bears are able to mate in summer. We report on a mating incident on 29 June 2014, the first documented mating this late in the season among wild polar bears. The female had lost her dependent cub during the period prior to the mating event. We speculate that she lost this cub late in the mating season, entered estrus and successfully mated in late June.

  7. Xenoendocrine pollutants May Reduce Size of Sexual Organs in East Greenland Polar Bears (Ursus Maritimus)

    DEFF Research Database (Denmark)

    Sonne, Christian; Leifsson, Pall S.; Dietz, Rune

    2006-01-01

    .01) and uterine horn length and HCB (p = 0.02). The study suggests thatthere is an impact from xenoendocrine pollutants on the size of East Greenland polar bear genitalia. This may pose a riskto this polar bear subpopulation in the future because of reduced sperm and egg quality/quantity and uterus and penis size......Reproductive organs from 55 male and 44 female East Greenland polar bears were examined to investigate the potential negative impact from organohalogen pollutants (OHCs). Multiple regressions normalizing for age showed a significant inverse relationship between OHCs and testis length and baculum...... length and weight, respectively, and was found in both subadults (dichlorodiphenyl trichloroethanes, dieldrin, chlordanes, hexacyclohexanes, polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs)) and adults (hexachlorobenzene [HCB]) (all p

  8. Factors influencing annual fecal testosterone metabolite profiles in captive male polar bears (Ursus maritimus).

    Science.gov (United States)

    Curry, E; Roth, T L; MacKinnon, K M; Stoops, M A

    2012-12-01

    The objectives of this study were to assess the effects of season, breeding activity, age and latitude on fecal testosterone metabolite concentrations in captive, adult male polar bears (Ursus maritimus). Fourteen polar bears from 13 North American zoos were monitored for 12-36 months, producing 25-year-long testosterone profiles. Results indicated that testosterone was significantly higher during the breeding season (early January through the end of May) compared with the non-breeding season with the highest concentrations excreted from early January through late March. Variations in excretion patterns were observed among individuals and also between years within an individual, with testosterone peaks closely associated with breeding activity. Results indicate that fecal testosterone concentrations are influenced by season, breeding activity and age, but not by latitude. This is the first report describing longitudinal fecal testosterone metabolite concentrations in individual adult male polar bears. © 2012 Blackwell Verlag GmbH.

  9. Movements of female polar bears (Usrus maritimus) in the East Greenland pack ice

    DEFF Research Database (Denmark)

    Wiig, Øystein; Born, Erik W.; Pedersen, Leif Toudal

    2003-01-01

    The movements of two adult female polar bears (Ursus maritimus) in East Greenland and the Greenland Sea area were studied by use of satellite telemetry between the fall of 1994 and the summer of 1998. One female was tracked for 621 days, the other for 1,415 days. During this time the females used...... for a closer monitoring of the effects of this change on the East Greenland polar bear population....... movement rates varied between 0.32 and 0.76km/h. Both bears had very large home ranges (242,000 and 468,000 km(2)) within the dynamic pack ice of the Greenland Sea. The facts that the bears made extensive use of the offshore sea ice and that there is a marked reduction of the Greenland Sea ice call...

  10. Prevalence of antibodies against Brucella spp. in West Greenland polar bears (Ursus maritimus) and East Greenland muskoxen (Ovibos moschatus)

    DEFF Research Database (Denmark)

    Sonne, Christian; Andersen-Ranberg, Emilie; Rajala, Elisabeth L.

    2018-01-01

    impact on human health due to consumption of raw meat or otherwise contact with tissues and fluids of infected game species such as muskoxen and polar bears. Here, we present serological results for Baffin Bay polar bears (Ursus maritimus) (n = 96) and North East Greenland muskoxen (Ovibos moschatus) (n...... in six polar bears (6.25%) rendering a seroprevalence in line with previous findings in other Arctic regions. Seropositivity was not related to sex, age or biometrics i.e. size and body condition. Whether Brucella spp. antibodies found in polar bears were due to either prey spill over or true recurrent...

  11. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

    Science.gov (United States)

    Amstrup, Steven C.; Deweaver, E.T.; Douglas, D.C.; Marcot, B.G.; Durner, G.M.; Bitz, C.M.; Bailey, D.A.

    2010-01-01

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the worlds polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

  12. Evaluation of hepatic biotransformation of polybrominated diphenyl ethers in the polar bear (Ursus maritimus).

    Science.gov (United States)

    Krieger, Lisa K; Szeitz, András; Bandiera, Stelvio M

    2016-03-01

    Polar bears are at the top of the Arctic marine food chain and are subject to exposure and bioaccumulation of environmental chemicals of concern such as polybrominated diphenyl ethers (PBDEs), which were widely used as flame retardants. The aim of the present study was to evaluate the in vitro oxidative metabolism of 2,2',4,4'-tetrabrominated diphenyl ether (BDE-47) and 2,2',4,4',5-pentabrominated diphenyl ether (BDE-99) by polar bear liver microsomes. The identification and quantification of the hydroxy-brominated diphenyl ethers formed were assessed using an ultra-high performance liquid chromatography-tandem mass spectrometry-based method. Incubation of BDE-47 with archived individual liver microsomes, prepared from fifteen polar bears from northern Canada, produced a total of eleven hydroxylated metabolites, eight of which were identified using authentic standards. The major metabolites were 4'-hydroxy-2,2',4,5'-tetrabromodiphenyl ether and 5'-hydroxy-2,2',4,4'-tetrabromodiphenyl ether. Incubation of BDE-99 with polar bear liver microsomes produced a total of eleven hydroxylated metabolites, seven of which were identified using authentic standards. The major metabolites were 2,4,5-tribromophenol and 4-hydroxy-2,2',3,4',5-pentabromodiphenyl ether. Among the CYP specific antibodies tested, anti-rat CYP2B was found to be the most active in inhibiting the formation of hydroxylated metabolites of both BDE-47 and BDE-99, indicating that CYP2B was the major CYP enzyme involved in the oxidative biotransformation of these two congeners. Our study shows that polar bears are capable of forming multiple hydroxylated metabolites of BDE-47 and BDE-99 in vitro and demonstrates the role of CYP2B in the biotransformation and possibly in the toxicity of BDE-47 and BDE-99 in polar bears. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Uncertainties in forecasting the response of polar bears to global climate change

    Science.gov (United States)

    Douglas, David C.; Atwood, Todd C.; Butterworth, Andy

    2017-01-01

    Several sources of uncertainty affect how precisely the future status of polar bears (Ursus maritimus) can be forecasted. Foremost are unknowns about the future levels of global greenhouse gas emissions, which could range from an unabated increase to an aggressively mitigated reduction. Uncertainties also arise because different climate models project different amounts and rates of future warming (and sea ice loss)—even for the same emission scenario. There are also uncertainties about how global warming could affect the Arctic Ocean’s food web, so even if climate models project the presence of sea ice in the future, the availability of polar bear prey is not guaranteed. Under a worst-case emission scenario in which rates of greenhouse gas emissions continue to rise unabated to century’s end, the uncertainties about polar bear status center on a potential for extinction. If the species were to persist, it would likely be restricted to a high-latitude refugium in northern Canada and Greenland—assuming a food web also existed with enough accessible prey to fuel weight gains for surviving onshore during the most extreme years of summer ice melt. On the other hand, if emissions were to be aggressively mitigated at the levels proposed in the Paris Climate Agreement, healthy polar bear populations would probably continue to occupy all but the most southern areas of their contemporary summer range. While polar bears have survived previous warming phases—which indicate some resiliency to the loss of sea ice habitat—what is certain is that the present pace of warming is unprecedented and will increasingly expose polar bears to historically novel stressors.

  14. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence.

    Science.gov (United States)

    Amstrup, Steven C; Deweaver, Eric T; Douglas, David C; Marcot, Bruce G; Durner, George M; Bitz, Cecilia M; Bailey, David A

    2010-12-16

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold. Such a tipping point would mean future greenhouse gas mitigation would confer no conservation benefits to polar bears. Here we show, using a general circulation model, that substantially more sea-ice habitat would be retained if greenhouse gas rise is mitigated. We also show, with Bayesian network model outcomes, that increased habitat retention under greenhouse gas mitigation means that polar bears could persist throughout the century in greater numbers and more areas than in the business-as-usual case. Our general circulation model outcomes did not reveal thresholds leading to irreversible loss of ice; instead, a linear relationship between global mean surface air temperature and sea-ice habitat substantiated the hypothesis that sea-ice thermodynamics can overcome albedo feedbacks proposed to cause sea-ice tipping points. Our outcomes indicate that rapid summer ice losses in models and observations represent increased volatility of a thinning sea-ice cover, rather than tipping-point behaviour. Mitigation-driven Bayesian network outcomes show that previously predicted declines in polar bear distribution and numbers are not unavoidable. Because polar bears are sentinels of the Arctic marine ecosystem and trends in their sea-ice habitats foreshadow future global changes, mitigating greenhouse gas emissions to improve polar bear status would have conservation benefits throughout

  15. Trends of perfluorochemicals in Greenland ringed seals and polar bears: indications of shifts to decreasing trends.

    Science.gov (United States)

    Rigét, Frank; Bossi, Rossana; Sonne, Christian; Vorkamp, Katrin; Dietz, Rune

    2013-11-01

    Time-series of perfluorinated alkylated substances (PFASs) in East Greenland polar bears and East and West Greenland ringed seals were updated in order to deduce whether a response to the major reduction in perfluoroalkyl production in the early 2000s had occurred. Previous studies had documented an exponential increase of perfluorooctane sulphonate (PFOS) in liver tissue from both species. In the present study, PFOS was still the far most dominant compound constituting 92% (West Greenland ringed seals), 88% (East Greenland ringed seals) and 85% (East Greenland polar bears). The PFOS concentrations increased up to 2006 with doubling times of approximately 6 years for the ringed seal populations and 14 years in case of polar bears. Since then a rapid decrease has occurred with clearing half-lives of approximately 1, 2 and 4 years, respectively. In polar bears perfluorohexane sulphonate (PFHxS) and perfluorooctane sulphonamide (PFOSA) also showed decreasing trends in recent years as do perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnA). For the West Greenland ringed seal population perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), PFDA and PFUnA peaked in the mid 2000s, whereas PFNA, PFDA and PFUnA in the East Greenland population have been stable or increasing in recent years. The peak of PFASs in Greenland ringed seals and polar bears occurred at a later time than in Canadian seals and polar bears and considerably later than observed in seal species from more southern latitudes. We suggest that this could be explained by the distance to emission hot-spots and differences in long-range transport to the Arctic. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Polar Bear Conservation Status in Relation to Projected Sea-ice Conditions

    Science.gov (United States)

    Regehr, E. V.

    2015-12-01

    The status of the world's 19 subpopulations of polar bears (Ursus maritimus) varies as a function of sea-ice conditions, ecology, management, and other factors. Previous methods to project the response of polar bears to loss of Arctic sea ice—the primary threat to the species—include expert opinion surveys, Bayesian Networks providing qualitative stressor assessments, and subpopulations-specific demographic analyses. Here, we evaluated the global conservation status of polar bears using a data-based sensitivity analysis. First, we estimated generation length for subpopulations with available data (n=11). Second, we developed standardized sea-ice metrics representing habitat availability. Third, we projected global population size under alternative assumptions for relationships between sea ice and subpopulation abundance. Estimated generation length (median = 11.4 years; 95%CI = 9.8 to 13.6) and sea-ice change (median = loss of 1.26 ice-covered days per year; 95%CI = 0.70 to 3.37) varied across subpopulations. Assuming a one-to-one proportional relationship between sea ice and abundance, the median percent change in global population size over three polar bear generations was -30% (95%CI = -35% to -25%). Assuming a linear relationship between sea ice and normalized estimates of subpopulation abundance, median percent change was -4% (95% CI = -62% to +50%) or -43% (95% CI = -76% to -20%), depending on how subpopulations were grouped and how inference was extended from relatively well-studied subpopulations (n=7) to those with little or no data. Our findings suggest the potential for large reductions in polar bear numbers over the next three polar bear generations if sea-ice loss due to climate change continues as forecasted.

  17. Methyl sulfone PCB and DDE metabolites in the polar bear (Ursus maritimus) food chain

    Energy Technology Data Exchange (ETDEWEB)

    Letcher, R.J. [Carleton Univ., Ottawa, Ontario (Canada); Norstrom, R.J. [Environment Canada, Hull, Quebec (Canada); Muir, D.C.G. [Dept. of Fisheries and Oceans, Winnipeg, Manitoba (Canada)

    1995-12-31

    An important Arctic marine food chain is polar bear, ringed seal (Phoca hispida) and Arctic cod (Boreogadus saida). The Arctic is relatively uncontaminated by chlorinated hydrocarbon contaminants (CHCs). However, high levels of CHCs are bioaccumulated through the marine food web. Methyl sulfone (MeSO{sub 2})-PCB and -DDE metabolites are major CHCs in polar bear, although the proportion of MeSO{sub 2}-PCBs derived from PCB metabolism and/or MeSO{sub 2}-PCB bioaccumulation from the diet is unknown. For this reason, the structure and concentration of MeSO{sup 2}-PCB and -DDE metabolites, PCBs and DDE were determined in whole body Arctic cod, the liver, adipose, lung and muscle of ringed seal and ten tissues of polar bear from the Resolute Bay area of the Canadian Arctic. Preliminary analysis of the ratios of MeSO{sub 2}-PCBs in bear fat and liver to their parent PCBs in seal blubber suggested that CB-49 and CB-87 result in a higher proportion of metabolites in bear than the other PCB congeners, assuming that the MeSO{sup 2}-PCBs are not themselves accumulated from the diet. Bio-availability of the precursor PCBs for subsequent metabolism may also be a factor. The absence in bears of MeSO{sub 2}-metabolites of other metabolizable PCBs in seal may indicate that some MeSO{sub 2}-PCBs are not formed or that they are formed and further metabolized. The MeSO{sub 2}-PCB and -DDE levels and congener patterns among seal and bear tissues and the difference in tissue distribution between species will also be compared. In polar bear, the s-MeSO{sub 2}-PCB to S-PCB and s-MeSO{sub 2}-DDE to DDE ratios were highest in liver, indicating preferred storage.

  18. Fossil Find on Svalbard Highlights the Natural History of the Polar Bear (Ursus maritimus)

    Science.gov (United States)

    Ingolfsson, O.; Wiig, O.

    2007-12-01

    During recent fieldwork on Svalbard a well preserved subfossil left ramus of a polar bear (Ursus maritimus) mandible was discovered. A 14C age determination shows that it is older than 45 ka (kilo-years), and an OSL (Optical Stimulated Luminescence) age determination together with the stratigraphic position of the bone suggests that it is of Eemian-Early Weichselian/Wisconsinan age, 150-80 ka old. This puts the find among the oldest fossil remains of a polar bear ever discovered. Osteological study of the mandible suggests that it comes from a fully grown female. The fossil record suggests that polar bears may have developed from brown bears during the early part of the last glacial cycle, some 100 ka ago. The present interglacial might be the first such that the species has to endure. This underlines the potential status of the polar bears as an endangered species if the current warming trend and diminishing of sea ice cover in the Arctic continues.

  19. Temporal trends and future predictions of mercury concentrations in Northwest Greenland polar bear (Ursus maritimus) hair.

    Science.gov (United States)

    Dietz, R; Born, E W; Rigét, F; Aubail, A; Sonne, C; Drimmie, R; Basu, N

    2011-02-15

    Hair samples from 117 Northwest Greenland polar bears (Ursus maritimus) were taken during 1892-2008 and analyzed for total mercury (hereafter Hg). The sample represented 28 independent years and the aim of the study was to analyze for temporal Hg trends. Mercury concentrations showed yearly significant increases of 1.6-1.7% (p bear Hg exposure is 95.6-96.2% anthropogenic in its origin. Assuming a continued anthropogenic increase, this model estimated concentrations in 2050 and 2100 will be 40- and 92-fold the baseline concentration, respectively, which is equivalent to a 97.5 and 98.9% man-made contribution. None of the 2001-2008 concentrations of Hg in Northwest Greenland polar bear hair exceeded the general guideline values of 20-30 μg/g dry weight for terrestrial wildlife, whereas the neurochemical effect level of 5.4 μg Hg/g dry weight proposed for East Greenland polar bears was exceeded in 93.5% of the cases. These results call for detailed effect studies in main target organs such as brain, liver, kidney, and sexual organs in the Northwest Greenland polar bears.

  20. Comparative analysis of fecal microbiota and intestinal microbial metabolic activity in captive polar bears.

    Science.gov (United States)

    Schwab, Clarissa; Gänzle, Michael

    2011-03-01

    The composition of the intestinal microbiota depends on gut physiology and diet. Ursidae possess a simple gastrointestinal system composed of a stomach, small intestine, and indistinct hindgut. This study determined the composition and stability of fecal microbiota of 3 captive polar bears by group-specific quantitative PCR and PCR-DGGE (denaturing gradient gel electrophoresis) using the 16S rRNA gene as target. Intestinal metabolic activity was determined by analysis of short-chain fatty acids in feces. For comparison, other Carnivora and mammals were included in this study. Total bacterial abundance was approximately log 8.5 DNA gene copies·(g feces)-1 in all 3 polar bears. Fecal polar bear microbiota was dominated by the facultative anaerobes Enterobacteriaceae and enterococci, and the Clostridium cluster I. The detection of the Clostridium perfringens α-toxin gene verified the presence of C. perfringens. Composition of the fecal bacterial population was stable on a genus level; according to results obtained by PCR-DGGE, dominant bacterial species fluctuated. The total short-chain fatty acid content of Carnivora and other mammals analysed was comparable; lactate was detected in feces of all carnivora but present only in trace amounts in other mammals. In comparison, the fecal microbiota and metabolic activity of captive polar bears mostly resembled the closely related grizzly and black bears.

  1. Correlation between the Flux Density and Polarization for Flat ...

    Indian Academy of Sciences (India)

    blazars, which show high and variable polarization, rapid variable flux density over different time scales (Fan 2005). Blazars consist of flat spectrum radio quasars. (FSRQs) and BL Lacertae objects (BLs). FSRQs are quite similar to BLs except for their emission line feature with FSRQs showing strong emission lines while.

  2. Correlation between the Flux Density and Polarization for Flat ...

    Indian Academy of Sciences (India)

    3Guangzhou Vocational College of Technology & Business, Guangzhou, China. 4Center for Astrophysics ... blazars, which show high and variable polarization, rapid variable flux density over different time scales (Fan ... emission lines while. BLs show very weak emission line feature or have only non-emission lines. The.

  3. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions

    OpenAIRE

    Rode, Karyn D.; Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Douglas, David C.; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013) when substantial summer sea-ice loss occurred. In bo...

  4. Resilience and risk: a demographic model to inform conservation planning for polar bears

    Science.gov (United States)

    Regehr, Eric V.; Wilson, Ryan R.; Rode, Karyn D.; Runge, Michael C.

    2015-01-01

    Climate change is having widespread ecological effects, including loss of Arctic sea ice. This has led to listing of the polar bear (Ursus maritimus) and other ice-dependent marine mammals under the U.S. Endangered Species Act (ESA). Methods are needed to evaluate the effects of climate change on population persistence to inform recovery planning for listed species. For polar bears, this includes understanding interactions between climate and secondary factors, such as subsistence harvest, which provide economic, nutritional, or cultural value to humans.

  5. Families in space: relatedness in the Barents Sea population of polar bears (Ursus maritimus).

    Science.gov (United States)

    Zeyl, E; Aars, J; Ehrich, D; Wiig, O

    2009-02-01

    The kin structure and dispersal pattern of polar bears (Ursus maritimus) of the Barents Sea was investigated during the spring mating season using two complementary approaches. First, individual genotypes based on the analyses of 27 microsatellite loci of 583 polar bears were related to field information gathered from 1146 bears in order to reconstruct the animals' pedigrees and to infer geographical distances between adult bears of different relatedness categories. According to the data, the median natal dispersal distance of the male animals was 52 km while that of the females was 93 km. Second, the relatedness of pairs of adult bears was estimated and correlated to the geographical distance between them. The female dyads had a much stronger kin structure than the male dyads. The 'pedigree approach' revealed a male kin structure which could not be detected using the 'relatedness approach'. This suggests that, on a broader scale, effective dispersal is slightly male biased. Despite fidelity to natal areas, male-mediated gene flow may nevertheless prevent genetic differentiation. Males might occasionally shift their home range which could therefore lead to a male-biased breeding dispersal. Our results showed that a nonterritorial species such as the polar bear that has a high dispersal potential, lives in a highly unstable environment and migrates seasonally is still able to exhibit a distinct kin structure during the mating season.

  6. An Evolutionarily Young Polar Bear (Ursus maritimus Endogenous Retrovirus Identified from Next Generation Sequence Data

    Directory of Open Access Journals (Sweden)

    Kyriakos Tsangaras

    2015-11-01

    Full Text Available Transcriptome analysis of polar bear (Ursus maritimus tissues identified sequences with similarity to Porcine Endogenous Retroviruses (PERV. Based on these sequences, four proviral copies and 15 solo long terminal repeats (LTRs of a newly described endogenous retrovirus were characterized from the polar bear draft genome sequence. Closely related sequences were identified by PCR analysis of brown bear (Ursus arctos and black bear (Ursus americanus but were absent in non-Ursinae bear species. The virus was therefore designated UrsusERV. Two distinct groups of LTRs were observed including a recombinant ERV that contained one LTR belonging to each group indicating that genomic invasions by at least two UrsusERV variants have recently occurred. Age estimates based on proviral LTR divergence and conservation of integration sites among ursids suggest the viral group is only a few million years old. The youngest provirus was polar bear specific, had intact open reading frames (ORFs and could potentially encode functional proteins. Phylogenetic analyses of UrsusERV consensus protein sequences suggest that it is part of a pig, gibbon and koala retrovirus clade. The young age estimates and lineage specificity of the virus suggests UrsusERV is a recent cross species transmission from an unknown reservoir and places the viral group among the youngest of ERVs identified in mammals.

  7. An Evolutionarily Young Polar Bear (Ursus maritimus) Endogenous Retrovirus Identified from Next Generation Sequence Data.

    Science.gov (United States)

    Tsangaras, Kyriakos; Mayer, Jens; Alquezar-Planas, David E; Greenwood, Alex D

    2015-11-24

    Transcriptome analysis of polar bear (Ursus maritimus) tissues identified sequences with similarity to Porcine Endogenous Retroviruses (PERV). Based on these sequences, four proviral copies and 15 solo long terminal repeats (LTRs) of a newly described endogenous retrovirus were characterized from the polar bear draft genome sequence. Closely related sequences were identified by PCR analysis of brown bear (Ursus arctos) and black bear (Ursus americanus) but were absent in non-Ursinae bear species. The virus was therefore designated UrsusERV. Two distinct groups of LTRs were observed including a recombinant ERV that contained one LTR belonging to each group indicating that genomic invasions by at least two UrsusERV variants have recently occurred. Age estimates based on proviral LTR divergence and conservation of integration sites among ursids suggest the viral group is only a few million years old. The youngest provirus was polar bear specific, had intact open reading frames (ORFs) and could potentially encode functional proteins. Phylogenetic analyses of UrsusERV consensus protein sequences suggest that it is part of a pig, gibbon and koala retrovirus clade. The young age estimates and lineage specificity of the virus suggests UrsusERV is a recent cross species transmission from an unknown reservoir and places the viral group among the youngest of ERVs identified in mammals.

  8. An Evolutionarily Young Polar Bear (Ursus maritimus) Endogenous Retrovirus Identified from Next Generation Sequence Data

    Science.gov (United States)

    Tsangaras, Kyriakos; Mayer, Jens; Alquezar-Planas, David E.; Greenwood, Alex D.

    2015-01-01

    Transcriptome analysis of polar bear (Ursus maritimus) tissues identified sequences with similarity to Porcine Endogenous Retroviruses (PERV). Based on these sequences, four proviral copies and 15 solo long terminal repeats (LTRs) of a newly described endogenous retrovirus were characterized from the polar bear draft genome sequence. Closely related sequences were identified by PCR analysis of brown bear (Ursus arctos) and black bear (Ursus americanus) but were absent in non-Ursinae bear species. The virus was therefore designated UrsusERV. Two distinct groups of LTRs were observed including a recombinant ERV that contained one LTR belonging to each group indicating that genomic invasions by at least two UrsusERV variants have recently occurred. Age estimates based on proviral LTR divergence and conservation of integration sites among ursids suggest the viral group is only a few million years old. The youngest provirus was polar bear specific, had intact open reading frames (ORFs) and could potentially encode functional proteins. Phylogenetic analyses of UrsusERV consensus protein sequences suggest that it is part of a pig, gibbon and koala retrovirus clade. The young age estimates and lineage specificity of the virus suggests UrsusERV is a recent cross species transmission from an unknown reservoir and places the viral group among the youngest of ERVs identified in mammals. PMID:26610552

  9. A novel endogenous betaretrovirus group characterized from polar bears (Ursus maritimus) and giant pandas (Ailuropoda melanoleuca)

    DEFF Research Database (Denmark)

    Mayer, Jens; Tsangaras, Kyriakos; Heeger, Felix

    2013-01-01

    . Molecular dating indicates the group originated before the divergence of bears from a common ancestor but is not present in all carnivores. Closely related sequences were identified in the giant panda (Ailuropoda melanoleuca) and characterized from its genome. We have designated the polar bear and giant...... panda sequences U. maritimus endogenous retrovirus (UmaERV) and A. melanoleuca endogenous retrovirus (AmeERV), respectively. Phylogenetic analysis demonstrated that the bear virus group is nested within the HERV-K supergroup among bovine and bat endogenous retroviruses suggesting a complex evolutionary...

  10. Evaluating and ranking threats to the long-term persistence of polar bears

    Science.gov (United States)

    Atwood, Todd C.; Marcot, Bruce G.; Douglas, David C.; Amstrup, Steven C.; Rode, Karyn D.; Durner, George M.; Bromaghin, Jeffrey F.

    2015-01-01

    The polar bear (Ursus maritimus) was listed as a globally threatened species under the U.S. Endangered Species Act (ESA) in 2008, mostly due to the significant threat to their future population viability from rapidly declining Arctic sea ice. A core mandate of the ESA is the development of a recovery plan that identifies steps to maintain viable populations of a listed species. A substantive evaluation of the relative influence of putative threats to population persistence is helpful to recovery planning. Because management actions must often be taken in the face of substantial information gaps, a formalized evaluation hypothesizing potential stressors and their relationships with population persistence can improve identification of relevant conservation actions. To this end, we updated a Bayesian network model previously used to forecast the future status of polar bears worldwide. We used new information on actual and predicted sea ice loss and polar bear responses to evaluate the relative influence of plausible threats and their mitigation through management actions on the persistence of polar bears in four ecoregions. We found that polar bear outcomes worsened over time through the end of the century under both stabilized and unabated greenhouse gas (GHG) emission pathways. Under the unabated pathway (i.e., RCP 8.5), the time it took for polar bear populations in two of four ecoregions to reach a dominant probability of greatly decreased was hastened by about 25 years. Under the stabilized GHG emission pathway (i.e., RCP 4.5), where GHG emissions peak around the year 2040, the polar bear population in the Archipelago Ecoregion of High Arctic Canada never reached a dominant probability of greatly decreased, reinforcing earlier suggestions of this ecoregion’s potential to serve as a long-term refugium. The most influential drivers of adverse polar bear outcomes were declines to overall sea ice conditions and to the marine prey base. Improved sea ice conditions

  11. Demography and behavior of polar bears summering on land in Alaska

    Science.gov (United States)

    Peacock, Lily

    2014-01-01

    Polar bears (Ursus maritimus) in the southern Beaufort Sea population (SB) are spending increased time on the coastal North Slope of Alaska between July and October (Gleason and Rode 2010). The duration spent on land by polar bears, satellite collared on the sea-ice in the spring, during the summer and fall has also increased (USGS, unpublished data; Figure 1). This change in polar bear ecology has relevance for human-bear interactions, subsistence harvest, prevalence of defense kills, and disturbance associated with existing land-based development [e.g., National Petroleum Reserve of Alaska (NPRA), Arctic National Wildlife Refuge (ANWR)], Native Alaskan communities, recreation (ANWR) and tourism (e.g., bear viewing in Kaktovik, AK). These activities have the potential to impact, in new ways, the status of the entire SB population. Concomitantly, the change in polar bear ecology will impact these human activities, and a base-line characterization of this phenomenon can better inform mitigation (e.g., industry permitting under the Endangered Species Act and Marine Mammal Protection Act). In this study we aim to characterize the demography, habitat-use, and aspects of foraging ecology and health of polar bears spending fall on land. The SB population is characterized by a divergent-sea ice ecology, where polar bears typically spend most of the year on the sea-ice, even as the pack ice retreats northward, away from the coast, to its minimal extent in September (Amstrup et al. 2008; Durner et al. 2009). From 2000 – 2005, using coastal aerial surveys, Schliebe et al. (2008) observed between 3.7 and 8% of polar bears from SB (~ 60 – 120 of 1526, Regher et al. 2006) on land during the autumn. Sighting probability was not estimated in these surveys, and therefore the numbers represent minimum numbers of bears on land. Our analysis of USGS data suggest an annual average of 15% (± 3%, SE) of polar bears satellite-tagged on the spring-time sea ice (total n = 18 of 124

  12. Brown and polar bear Y chromosomes reveal extensive male-biased gene flow within brother lineages.

    Science.gov (United States)

    Bidon, Tobias; Janke, Axel; Fain, Steven R; Eiken, Hans Geir; Hagen, Snorre B; Saarma, Urmas; Hallström, Björn M; Lecomte, Nicolas; Hailer, Frank

    2014-06-01

    Brown and polar bears have become prominent examples in phylogeography, but previous phylogeographic studies relied largely on maternally inherited mitochondrial DNA (mtDNA) or were geographically restricted. The male-specific Y chromosome, a natural counterpart to mtDNA, has remained underexplored. Although this paternally inherited chromosome is indispensable for comprehensive analyses of phylogeographic patterns, technical difficulties and low variability have hampered its application in most mammals. We developed 13 novel Y-chromosomal sequence and microsatellite markers from the polar bear genome and screened these in a broad geographic sample of 130 brown and polar bears. We also analyzed a 390-kb-long Y-chromosomal scaffold using sequencing data from published male ursine genomes. Y chromosome evidence support the emerging understanding that brown and polar bears started to diverge no later than the Middle Pleistocene. Contrary to mtDNA patterns, we found 1) brown and polar bears to be reciprocally monophyletic sister (or rather brother) lineages, without signals of introgression, 2) male-biased gene flow across continents and on phylogeographic time scales, and 3) male dispersal that links the Alaskan ABC islands population to mainland brown bears. Due to female philopatry, mtDNA provides a highly structured estimate of population differentiation, while male-biased gene flow is a homogenizing force for nuclear genetic variation. Our findings highlight the importance of analyzing both maternally and paternally inherited loci for a comprehensive view of phylogeographic history, and that mtDNA-based phylogeographic studies of many mammals should be reevaluated. Recent advances in sequencing technology render the analysis of Y-chromosomal variation feasible, even in nonmodel organisms. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e

  13. Post-den emergence behavior of polar bears (Ursus maritimus) in Northern Alaska

    Science.gov (United States)

    Smith, T.S.; Partridge, Steven T.; Amstrup, Steven C.; Schliebe, S.

    2007-01-01

    We observed polar bear (Ursus maritimus) maternity den sites on Alaska’s North Slope in March 2002 and 2003 in an effort to describe bears’ post-den emergence behavior. During 40 sessions spanning 459 h, we observed 8 adults and 14 dependent cubs outside dens for 37.5 h (8.2% of total observation time). There was no significant difference between den emergence dates in 2002 (mean = 15 Mar ± 4.1 d) and 2003 (mean = 21 Mar ± 2.1 d). Following initial den breakout, polar bears remained at their den sites for 1.5 to 14 days (mean = 8.1 ± 5.1 d). The average length of stay in dens between emergent periods was significantly shorter in 2002 (1.79 h) than in 2003 (4.82 h). While outside, adult bears were inactive 49.5% of the time, whereas cubs were inactive 13.4% of the time. We found no significant relationships between den emergence activity and weather. Adult polar bears at den sites subjected to industrial activity exhibited significantly fewer bouts of vigilance than denned bears in undisturbed areas (t = -5.5164, df = 4, p= 0.00). However, the duration of vigilance behaviors at sites near industrial activity was not significantly shorter than at the other sites studied (t = -1.8902, df = 4, p = 0.07). Results for these bears were within the range of findings in other studies of denned polar bears.

  14. Longitudinal fecal hormone analysis for monitoring reproductive activity in the female polar bear (Ursus maritimus).

    Science.gov (United States)

    Stoops, M A; MacKinnon, K M; Roth, T L

    2012-12-01

    The objective was to identify suitable enzyme immunoassays to monitor gonadal and placental function in the female polar bear. Immunoreactive progesterone, progesterone metabolite (PdG), estrogen, and androgen metabolite (T) concentrations were measured in fecal samples collected over 24 mo from captive female bears (N = 20). Whereas fecal extracts produced displacement curves parallel to the standard curve for each respective steroid, T and PdG more accurately reflected reproductive events. Concentrations of fecal T increased (P < 0.05) during the breeding season, and brief spikes were associated with estrus and mating. A postovulatory increase in PdG was not always detected, but sustained baseline T after mating appeared consistent with ovulation. Parturient bears excreted higher PdG concentrations (P < 0.05) during expected time of embryo implantation in Fall, and a late gestational rise in fecal T occurred 30 days prepartum. Many nonparturient bears also had a PdG rise in the Fall, suggesting they experienced either pregnancy loss or a pseudopregnancy. Differentiating pregnant and pseudopregnant states was not achieved using fecal PdG alone, but when combined with fecal T, comprehensive diagnoses could be made. Nonparturient bears demonstrated elevated (P < 0.05) fecal T during summer months, whereas parturient bears did not. In summary, noninvasive hormone monitoring techniques were established for the female polar bear. Although this study was directed at facilitating management and breeding efforts of captive polar bears, the methods could be applied to studies of reproductive function in wild populations. Copyright © 2012 Elsevier Inc. All rights reserved.

  15. Use of spatial capture–recapture to estimate density of Andean bears in northern Ecuador

    Science.gov (United States)

    Molina, Santiago; Fuller, Angela K.; Morin, Dana J.; Royle, J. Andrew

    2017-01-01

    The Andean bear (Tremarctos ornatus) is the only extant species of bear in South America and is considered threatened across its range and endangered in Ecuador. Habitat loss and fragmentation is considered a critical threat to the species, and there is a lack of knowledge regarding its distribution and abundance. The species is thought to occur at low densities, making field studies designed to estimate abundance or density challenging. We conducted a pilot camera-trap study to estimate Andean bear density in a recently identified population of Andean bears northwest of Quito, Ecuador, during 2012. We compared 12 candidate spatial capture–recapture models including covariates on encounter probability and density and estimated a density of 7.45 bears/100 km2 within the region. In addition, we estimated that approximately 40 bears used a recently named Andean bear corridor established by the Secretary of Environment, and we produced a density map for this area. Use of a rub-post with vanilla scent attractant allowed us to capture numerous photographs for each event, improving our ability to identify individual bears by unique facial markings. This study provides the first empirically derived density estimate for Andean bears in Ecuador and should provide direction for future landscape-scale studies interested in conservation initiatives requiring spatially explicit estimates of density.

  16. Xenoestrogenic and dioxin-like activity in blood of East Greenland polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Erdmann, Simon Erik; Dietz, Rune; Sonne, Christian

    2013-01-01

    The aims of the project were to (i) extract the lipophilic persistent organic pollutants (POPs) from the blood of 99 East Greenland polar bears and assess the combined mixture effect on the estrogen receptor (ER) and the aryl hydrocarbon receptor (AhR) mediated transactivity; (ii) To evaluate whe...

  17. Polar Bear UV Imaging of Airglow and Aurora - Image Processing and Results

    Science.gov (United States)

    1989-09-24

    L., Huffman, R. E., Rich, F. J., Meng, C. - I., Potocki , K. A., Potemra, T. A., Hanson, W. B., Heelis, R. A., and Wittwer, L. A., The HILAT program...0177, ADA214203 [13) Osnovich, I., and Tur, M., Stabilising the Polar BEAR Retrospectively, Research Progress and Forecast Report to AFGL, Jan . 1989

  18. Allee effect in polar bears: A potential consequence of polychlorinated biphenyl contamination.

    Czech Academy of Sciences Publication Activity Database

    Pavlová, Viola; Nabe-Nielsen, J.; Dietz, R.; Sonne, C.; Grimm, V.

    2016-01-01

    Roč. 283, č. 1843 (2016), č. článku 20161883. ISSN 0962-8452 Institutional support: RVO:60077344 Keywords : allee effect * polychlorinated biphenyls * polar bear s * male reproduction Subject RIV: EH - Ecology, Behaviour Impact factor: 4.940, year: 2016

  19. Greenhouse gas mitigation can reduce sea-ice loss and increase polar bear persistence

    Science.gov (United States)

    Steven C. Amstrup; Eric T. DeWeaver; David C. Douglas; Bruce G. Marcot; George M. Durner; Cecilia M. Bitz; David A. Bailey

    2010-01-01

    On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible...

  20. Experiencing polar bears in the zoo: feelings and cognitions in relation to a visitor's conservation attitude

    NARCIS (Netherlands)

    Marseille, M.M.; Elands, B.H.M.; Brink, van den M.L.

    2012-01-01

    This article explores which feelings and cognitions are involved in visitor experiences of zoo polar bears and how this experience relates to a visitor's conservation attitude. Data were collected through qualitative interviews with 30 visitors in two Dutch zoos. Most respondents believed that a

  1. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears

    Science.gov (United States)

    Todd C. Atwood; Bruce G. Marcot; David C. Douglas; Steven C. Amstrup; Karyn D. Rode; George M. Durner; Jeffrey F. Bromaghin

    2016-01-01

    Effective conservation planning requires understanding and ranking threats to wildlife populations. We developed a Bayesian network model to evaluate the relative influence of environmental and anthropogenic stressors, and their mitigation, on the persistence of polar bears (Ursus maritimus). Overall sea ice conditions, affected by rising global...

  2. High‐frequency induced polarization measurements of hydrocarbon‐bearing rocks

    DEFF Research Database (Denmark)

    Burtman, Vladimir; Endo, Masashi; Zhdanov, Michael S.

    2011-01-01

    We have investigated induced polarization (IP) effects in hydrocarbon‐bearing artificial rocks at frequencies greater than 100 Hz. We have examined the instrumental and electrode phase responses of Zonge International's complex resistivity (CR) system, and optimized the performance of the Zonge s......, and suggest the necessity to account for IP effects in the interpretations of electromagnetic data, particularly in induction logging data....

  3. Transthyretin-Binding Activity of Contaminants in Blood from Polar Bear (Ursus maritimus) Cubs

    NARCIS (Netherlands)

    Bytingsvik, J.; Simon, E.; Leonards, P.E.G.; Lamoree, M.H.; Lie, E.; Aars, J.; Derocher, A. E.; Wiig, O.; Jenssen, B.M.; Hamers, T.

    2013-01-01

    We determined the transthyretin (TTR)-binding activity of blood-accumulating contaminants in blood plasma samples of approximately 4-months-old polar bear (Ursus maritimus) cubs from Svalbard sampled in 1998 and 2008. The TTR-binding activity was measured as thyroxine (T4)-like equivalents (T4-EQ

  4. Breeding facilities for polar bears, Thalarctos maritimus (Phipps, 1774), in captivity

    NARCIS (Netherlands)

    Jacobi, E.F.

    1968-01-01

    The breeding results of Polar Bears in captivity are in general very disappointing. Unsuitable maternity dens are the main cause. These should be completely closed, very quiet without outside disturbances and should have connection with a run and thus with an outside enclosure. The female should be

  5. A novel endogenous betaretrovirus group characterized from polar bears (Ursus maritimus) and giant pandas (Ailuropoda melanoleuca).

    Science.gov (United States)

    Mayer, Jens; Tsangaras, Kyriakos; Heeger, Felix; Avila-Arcos, María; Stenglein, Mark D; Chen, Wei; Sun, Wei; Mazzoni, Camila J; Osterrieder, Nikolaus; Greenwood, Alex D

    2013-08-15

    Transcriptome analysis of polar bears (Ursus maritimus) yielded sequences with highest similarity to the human endogenous retrovirus group HERV-K(HML-2). Further analysis of the polar bear draft genome identified an endogenous betaretrovirus group comprising 26 proviral copies and 231 solo LTRs. Molecular dating indicates the group originated before the divergence of bears from a common ancestor but is not present in all carnivores. Closely related sequences were identified in the giant panda (Ailuropoda melanoleuca) and characterized from its genome. We have designated the polar bear and giant panda sequences U. maritimus endogenous retrovirus (UmaERV) and A. melanoleuca endogenous retrovirus (AmeERV), respectively. Phylogenetic analysis demonstrated that the bear virus group is nested within the HERV-K supergroup among bovine and bat endogenous retroviruses suggesting a complex evolutionary history within the HERV-K group. All individual remnants of proviral sequences contain numerous frameshifts and stop codons and thus, the virus is likely non-infectious. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Effect-Directed Analysis to Explore the Polar Bear Exposome: the Identification of Thyroid Hormone Disrupting Compounds in Plasma

    NARCIS (Netherlands)

    Simon, E.; van Velzen, M.J.M.; Brandsma, S.H.; Lie, E.; Loken, K.; de Boer, J.; Bytingsvik, J.; Jenssen, B.M.; Aars, J.; Hamers, T.; Lamoree, M.H.

    2013-01-01

    Compounds with transthyretin (TTR)-binding potency in the blood plasma of polar bear cubs were identified with effect-directed analysis (EDA). This approach contributes to the understanding of the thyroid disrupting exposome of polar bears. The selection of these samples for in-depth EDA was based

  7. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear.

    Science.gov (United States)

    Pagano, A M; Durner, G M; Rode, K D; Atwood, T C; Atkinson, S N; Peacock, E; Costa, D P; Owen, M A; Williams, T M

    2018-02-02

    Regional declines in polar bear ( Ursus maritimus ) populations have been attributed to changing sea ice conditions, but with limited information on the causative mechanisms. By simultaneously measuring field metabolic rates, daily activity patterns, body condition, and foraging success of polar bears moving on the spring sea ice, we found that high metabolic rates (1.6 times greater than previously assumed) coupled with low intake of fat-rich marine mammal prey resulted in an energy deficit for more than half of the bears examined. Activity and movement on the sea ice strongly influenced metabolic demands. Consequently, increases in mobility resulting from ongoing and forecasted declines in and fragmentation of sea ice are likely to increase energy demands and may be an important factor explaining observed declines in body condition and survival. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  8. Polar bear population dynamics in the southern Beaufort Sea during a period of sea ice decline

    Science.gov (United States)

    Bromaghin, Jeffrey F.; McDonald, Trent L.; Stirling, Ian; Derocher, Andrew E.; Richardson, Evan S.; Regehr, Eric V.; Douglas, David C.; Durner, George M.; Atwood, Todd C.; Amstrup, Steven C.

    2015-01-01

    In the southern Beaufort Sea of the United States and Canada, prior investigations have linked declines in summer sea ice to reduced physical condition, growth, and survival of polar bears (Ursus maritimus). Combined with projections of population decline due to continued climate warming and the ensuing loss of sea ice habitat, those findings contributed to the 2008 decision to list the species as threatened under the U.S. Endangered Species Act. Here, we used mark–recapture models to investigate the population dynamics of polar bears in the southern Beaufort Sea from 2001 to 2010, years during which the spatial and temporal extent of summer sea ice generally declined. Low survival from 2004 through 2006 led to a 25–50% decline in abundance. We hypothesize that low survival during this period resulted from (1) unfavorable ice conditions that limited access to prey during multiple seasons; and possibly, (2) low prey abundance. For reasons that are not clear, survival of adults and cubs began to improve in 2007 and abundance was comparatively stable from 2008 to 2010, with ~900 bears in 2010 (90% CI 606–1212). However, survival of subadult bears declined throughout the entire period. Reduced spatial and temporal availability of sea ice is expected to increasingly force population dynamics of polar bears as the climate continues to warm. However, in the short term, our findings suggest that factors other than sea ice can influence survival. A refined understanding of the ecological mechanisms underlying polar bear population dynamics is necessary to improve projections of their future status and facilitate development of management strategies.

  9. Polar bears (Ursus maritimus), the most evolutionary advanced hibernators, avoid significant bone loss during hibernation.

    Science.gov (United States)

    Lennox, Alanda R; Goodship, Allen E

    2008-02-01

    Some hibernating animals are known to reduce muscle and bone loss associated with mechanical unloading during prolonged immobilisation,compared to humans. However, here we show that wild pregnant polar bears (Ursus maritimus) are the first known animals to avoid significant bone loss altogether, despite six months of continuous hibernation. Using serum biochemical markers of bone turnover, we showed that concentrations for bone resorption are not significantly increased as a consequence of hibernation in wild polar bears. This is in sharp contrast to previous studies on other hibernating species, where for example, black bears (Ursus americanus), show a 3-4 fold increase in serum bone resorption concentrations posthibernation,and must compensate for this loss through rapid bone recovery on remobilisation, to avoid the risk of fracture. In further contrast to black bears, serum concentrations of bone formation markers were highly significantly increased in pregnant female polar bears compared to non-pregnant,thus non-hibernating females both prior to and after hibernation. However, bone formation concentrations in new mothers were significantly reduced compared to pre-hibernation concentrations. The de-coupling of bone turnover in favour of bone formation prior to hibernation, suggests that wild polar bears may posses a unique physiological mechanism for building bone in protective preparation against expected osteopenia associated with disuse,starvation, and hormonal drives to mobilise calcium for reproduction, during hibernation. Understanding this physiological mechanism could have profound implications for a natural solution for the prevention of osteoporosis in animals subjected to captivity with inadequate space for exercise,humans subjected to prolonged bed rest while recovering from illness, or astronauts exposed to antigravity during spaceflight.© 2008 Elsevier Inc. All rights reserved.

  10. Circumpolar Genetic Structure and Recent Gene Flow of Polar Bears: A Reanalysis.

    Science.gov (United States)

    Malenfant, René M; Davis, Corey S; Cullingham, Catherine I; Coltman, David W

    2016-01-01

    Recently, an extensive study of 2,748 polar bears (Ursus maritimus) from across their circumpolar range was published in PLOS ONE, which used microsatellites and mitochondrial haplotypes to apparently show altered population structure and a dramatic change in directional gene flow towards the Canadian Archipelago-an area believed to be a future refugium for polar bears as their southernmost habitats decline under climate change. Although this study represents a major international collaborative effort and promised to be a baseline for future genetics work, methodological shortcomings and errors of interpretation undermine some of the study's main conclusions. Here, we present a reanalysis of this data in which we address some of these issues, including: (1) highly unbalanced sample sizes and large amounts of systematically missing data; (2) incorrect calculation of FST and of significance levels; (3) misleading estimates of recent gene flow resulting from non-convergence of the program BayesAss. In contrast to the original findings, in our reanalysis we find six genetic clusters of polar bears worldwide: the Hudson Bay Complex, the Western and Eastern Canadian Arctic Archipelago, the Western and Eastern Polar Basin, and-importantly-we reconfirm the presence of a unique and possibly endangered cluster of bears in Norwegian Bay near Canada's expected last sea-ice refugium. Although polar bears' abundance, distribution, and population structure will certainly be negatively affected by ongoing-and increasingly rapid-loss of Arctic sea ice, these genetic data provide no evidence of strong directional gene flow in response to recent climate change.

  11. Relationships between POPs, biometrics and circulating steroids in male polar bears (Ursus maritimus) from Svalbard.

    Science.gov (United States)

    Ciesielski, Tomasz M; Hansen, Ingunn Tjelta; Bytingsvik, Jenny; Hansen, Martin; Lie, Elisabeth; Aars, Jon; Jenssen, Bjørn M; Styrishave, Bjarne

    2017-11-01

    The aim of this study was to determine the effects of persistent organic pollutants (POPs) and biometric variables on circulating levels of steroid hormones (androgens, estrogens and progestagens) in male polar bears (Ursus maritimus) from Svalbard, Norway (n = 23). Levels of pregnenolone (PRE), progesterone (PRO), androstenedione (AN), dehydroepiandrosterone (DHEA), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2) and 17β-estradiol (βE2) were quantified in polar bear serum by gas chromatography tandem mass spectrometry (GC-MS/MS), while POPs were measured in plasma. Subsequently, associations between hormone concentrations (9 steroids), POPs (21 polychlorinated biphenyls (PCBs), 8 OH-PCBs, 8 organochlorine pesticides (OCPs) and OCP metabolites, and 2 polybrominated diphenyl ethers (PBDEs)) and biological variables (age, head length, body mass, girth, body condition index), capture date, location (latitude and longitude), lipid content and cholesterol levels were examined using principal component analysis (PCA) and orthogonal projections to latent structures (OPLS) modelling. Average concentrations of androgens, estrogens and progestagens were in the range of 0.57-83.7 (0.57-12.4 for subadults, 1.02-83.7 for adults), 0.09-2.69 and 0.57-2.44 nmol/L, respectively. The steroid profiles suggest that sex steroids were mainly synthesized through the Δ-4 pathway in male polar bears. The ratio between androgens and estrogens significantly depended on sexual maturity with androgen/estrogen ratios being approximately 60 times higher in adult males than in subadult males. PCA plots and OPLS models indicated that TS was positively related to biometrics, such as body condition index in male polar bears. A negative relationship was also observed between POPs and DHT. Consequently, POPs and body condition may potentially affect the endocrinological function of steroids, including development of reproductive tissues and sex organs and the

  12. Hydroxylated polychlorinated biphenyls decrease circulating steroids in female polar bears (Ursus maritimus).

    Science.gov (United States)

    Gustavson, Lisa; Ciesielski, Tomasz M; Bytingsvik, Jenny; Styrishave, Bjarne; Hansen, Martin; Lie, Elisabeth; Aars, Jon; Jenssen, Bjørn M

    2015-04-01

    As a top predator in the Arctic food chain, polar bears (Ursus maritimus) are exposed to high levels of persistent organic pollutants (POPs). Because several of these compounds have been reported to alter endocrine pathways, such as the steroidogenesis, potential disruption of the sex steroid synthesis by POPs may cause implications for reproduction by interfering with ovulation, implantation and fertility. Blood samples were collected from 15 female polar bears in Svalbard (Norway) in April 2008. The concentrations of nine circulating steroid hormones; dehydroepiandrosterone (DHEA), androstenedione (AN), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), 17α-estradiol (αE2), 17β-estradiol (βE2), pregnenolone (PRE) and progesterone (PRO) were determined. The aim of the study was to investigate associations among circulating levels of specific POP compounds and POP-metabolites (hydroxylated PCBs [OH-PCBs] and hydroxylated PBDEs [OH-PBDEs]), steroid hormones, biological and capture variables in female polar bears. Inverse correlations were found between circulating levels of PRE and AN, and circulating levels of OH-PCBs. There were no significant relationships between the steroid concentrations and other analyzed POPs or the variables capture date and capture location (latitude and longitude), lipid content, condition and body mass. Although statistical associations do not necessarily represent direct cause-effect relationships, the present study indicate that OH-PCBs may affect the circulating levels of AN and PRE in female polar bears and that OH-PCBs thus may interfere with the steroid homeostasis. Increase in PRO and a decrease in AN concentrations suggest that the enzyme CYP17 may be a potential target for OH-PCBs. In combination with natural stressors, ongoing climate change and contaminant exposure, it is possible that OH-PCBs may disturb the reproductive potential of polar bears. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Circumpolar Genetic Structure and Recent Gene Flow of Polar Bears: A Reanalysis.

    Directory of Open Access Journals (Sweden)

    René M Malenfant

    Full Text Available Recently, an extensive study of 2,748 polar bears (Ursus maritimus from across their circumpolar range was published in PLOS ONE, which used microsatellites and mitochondrial haplotypes to apparently show altered population structure and a dramatic change in directional gene flow towards the Canadian Archipelago-an area believed to be a future refugium for polar bears as their southernmost habitats decline under climate change. Although this study represents a major international collaborative effort and promised to be a baseline for future genetics work, methodological shortcomings and errors of interpretation undermine some of the study's main conclusions. Here, we present a reanalysis of this data in which we address some of these issues, including: (1 highly unbalanced sample sizes and large amounts of systematically missing data; (2 incorrect calculation of FST and of significance levels; (3 misleading estimates of recent gene flow resulting from non-convergence of the program BayesAss. In contrast to the original findings, in our reanalysis we find six genetic clusters of polar bears worldwide: the Hudson Bay Complex, the Western and Eastern Canadian Arctic Archipelago, the Western and Eastern Polar Basin, and-importantly-we reconfirm the presence of a unique and possibly endangered cluster of bears in Norwegian Bay near Canada's expected last sea-ice refugium. Although polar bears' abundance, distribution, and population structure will certainly be negatively affected by ongoing-and increasingly rapid-loss of Arctic sea ice, these genetic data provide no evidence of strong directional gene flow in response to recent climate change.

  14. Polar bear population status in the northern Beaufort Sea, Canada, 1971-2006.

    Science.gov (United States)

    Stirling, Ian; McDonald, Trent L; Richardson, E S; Regehr, Eric V; Amstrup, Steven C

    2011-04-01

    Polar bears (Ursus maritimus) of the northern Beaufort Sea (NB) population occur on the perimeter of the polar basin adjacent to the northwestern islands of the Canadian Arctic Archipelago. Sea ice converges on the islands through most of the year. We used open-population capture-recapture models to estimate population size and vital rates of polar bears between 1971 and 2006 to: (1) assess relationships between survival, sex and age, and time period; (2) evaluate the long-term importance of sea ice quality and availability in relation to climate warming; and (3) note future management and conservation concerns. The highest-ranking models suggested that survival of polar bears varied by age class and with changes in the sea ice habitat. Model-averaged estimates of survival (which include harvest mortality) for senescent adults ranged from 0.37 to 0.62, from 0.22 to 0.68 for cubs of the year (COY) and yearlings, and from 0.77 to 0.92 for 2-4 year-olds and adults. Horvtiz-Thompson (HT) estimates of population size were not significantly different among the decades of our study. The population size estimated for the 2000s was 980 +/- 155 (mean and 95% CI). These estimates apply primarily to that segment of the NB population residing west and south of Banks Island. The NB polar bear population appears to have been stable or possibly increasing slightly during the period of our study. This suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels. However, the amount of ice remaining in the study area at the end of summer, and the proportion that continues to lie over the biologically productive continental shelf (polar bear population in the northern Beaufort Sea will eventually decline. Management and conservation practices for polar bears in relation to both aboriginal harvesting and offshore industrial activity will need to

  15. Characterization of a pancreatic islet cell tumor in a polar bear (Ursus maritimus).

    Science.gov (United States)

    Fortin, Jessica S; Benoit-Biancamano, Marie-Odile

    2014-01-01

    Herein, we report a 25-year-old male polar bear suffering from a pancreatic islet cell tumor. The aim of this report is to present a case of this rare tumor in a captive polar bear. The implication of potential risk factors such as high carbohydrate diet or the presence of amyloid fibril deposits was assessed. Necropsy examination revealed several other changes, including nodules observed in the liver, spleen, pancreas, intestine, and thyroid glands that were submitted for histopathologic analysis. Interestingly, the multiple neoplastic nodules were unrelated and included a pancreatic islet cell tumor. Immunohistochemistry of the pancreas confirmed the presence of insulin and islet amyloid polypeptide (IAPP) within the pancreatic islet cells. The IAPP gene was extracted from the paraffin-embedded liver tissue and sequenced. IAPP cDNA from the polar bear exhibits some differences as compared to the sequence published for several other species. Different factors responsible for neoplasms in bears such as diet, infectious agents, and industrial chemical exposure are reviewed. This case report raised several issues that further studies may address by evaluating the prevalence of cancers in captive or wild animals. © 2014 Wiley Periodicals, Inc.

  16. Reduced body size and cub recruitment in polar bears associated with sea ice decline

    Science.gov (United States)

    Rode, K.D.; Amstrup, Steven C.; Regehr, E.V.

    2010-01-01

    Rates of reproduction and survival are dependent upon adequate body size and condition of individuals. Declines in size and condition have provided early indicators of population decline in polar bears (Ursus maritimus) near the southern extreme of their range. We tested whether patterns in body size, condition, and cub recruitment of polar bears in the southern Beaufort Sea of Alaska were related to the availability of preferred sea ice habitats and whether these measures and habitat availability exhibited trends over time, between 1982 and 2006. The mean skull size and body length of all polar bears over three years of age declined over time, corresponding with long-term declines in the spatial and temporal availability of sea ice habitat. Body size of young, growing bears declined over time and was smaller after years when sea ice availability was reduced. Reduced litter mass and numbers of yearlings per female following years with lower availability of optimal sea ice habitat, suggest reduced reproductive output and juvenile survival. These results, based on analysis of a longterm data set, suggest that declining sea ice is associated with nutritional limitations that reduced body size and reproduction in this population. ?? 2010 by the Ecological Society of America.

  17. Bacterial diversity in faeces from polar bear (Ursus maritimus) in Arctic Svalbard.

    Science.gov (United States)

    Glad, Trine; Bernhardsen, Pål; Nielsen, Kaare M; Brusetti, Lorenzo; Andersen, Magnus; Aars, Jon; Sundset, Monica A

    2010-01-14

    Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81 degrees N, 10-33 degrees E). In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006. A 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70%) were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 x 10(4) to 1.6 x 10(6) colony forming units (cfu)/ml for the rectum swabs and 4.0 x 10(3) to 1.0 x 10(5) cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic beta-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears. The bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations.

  18. Bacterial diversity in faeces from polar bear (Ursus maritimus) in Arctic Svalbard

    Science.gov (United States)

    2010-01-01

    Background Polar bears (Ursus maritimus) are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81°N, 10-33°E). In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr) were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006. Results A 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70%) were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 × 104 to 1.6 × 106 colony forming units (cfu)/ml for the rectum swabs and 4.0 × 103 to 1.0 × 105 cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic β-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears. Conclusion The bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations. PMID:20074323

  19. Bacterial diversity in faeces from polar bear (Ursus maritimus in Arctic Svalbard

    Directory of Open Access Journals (Sweden)

    Brusetti Lorenzo

    2010-01-01

    Full Text Available Abstract Background Polar bears (Ursus maritimus are major predators in the Arctic marine ecosystem, feeding mainly on seals, and living closely associated with sea ice. Little is known of their gut microbial ecology and the main purpose of this study was to investigate the microbial diversity in faeces of polar bears in Svalbard, Norway (74-81°N, 10-33°E. In addition the level of blaTEM alleles, encoding ampicillin resistance (ampr were determined. In total, ten samples were collected from ten individual bears, rectum swabs from five individuals in 2004 and faeces samples from five individuals in 2006. Results A 16S rRNA gene clone library was constructed, and all sequences obtained from 161 clones showed affiliation with the phylum Firmicutes, with 160 sequences identified as Clostridiales and one sequence identified as unclassified Firmicutes. The majority of the sequences (70% were affiliated with the genus Clostridium. Aerobic heterotrophic cell counts on chocolate agar ranged between 5.0 × 104 to 1.6 × 106 colony forming units (cfu/ml for the rectum swabs and 4.0 × 103 to 1.0 × 105 cfu/g for the faeces samples. The proportion of ampr bacteria ranged from 0% to 44%. All of 144 randomly selected ampr isolates tested positive for enzymatic β-lactamase activity. Three % of the ampr isolates from the rectal samples yielded positive results when screened for the presence of blaTEM genes by PCR. BlaTEM alleles were also detected by PCR in two out of three total faecal DNA samples from polar bears. Conclusion The bacterial diversity in faeces from polar bears in their natural environment in Svalbard is low compared to other animal species, with all obtained clones affiliating to Firmicutes. Furthermore, only low levels of blaTEM alleles were detected in contrast to their increasing prevalence in some clinical and commensal bacterial populations.

  20. Barents Sea polar bears (Ursus maritimus: population biology and anthropogenic threats

    Directory of Open Access Journals (Sweden)

    Magnus Andersen

    2016-07-01

    Full Text Available This paper examines how anthropogenic threats, such as disturbance, pollution and climate change, are linked to polar bear (Ursus maritimus population biology in the Svalbard and Barents Sea area, with the aim to increase our understanding of how human activity may impact the population. Overharvesting drastically reduced the population of polar bears in the Barents Sea region from about 1870 to 1970. After harvesting was stopped—in 1956 in Russia and 1973 in Norway—the population grew to an estimated 2650 individuals (95% confidence interval 1900–3600 in 2004, and maternity denning in the Svalbard Archipelago became more widely distributed. During recent decades, the population has faced challenges from a variety of new anthropogenic impacts: a range of pollutants, an increasing level of human presence and activity as well as changes in ice conditions. Contaminants bioaccumulate up through the marine food web, culminating in this top predator that consumes ringed, bearded and harp seals. Females with small cubs use land-fast sea ice for hunting and are therefore vulnerable to disturbance by snowmobile drivers. Sea-ice diminution, associated with climate change, reduces polar bears’ access to denning areas and could negatively affect the survival of cubs. There are clear linkages between population biology and current anthropogenic threats, and we suggest that future research and management should focus on and take into consideration the combined effects of several stressors on polar bears.

  1. Xenoestrogenic and dioxin-like activity in blood of East Greenland polar bears (Ursus maritimus).

    Science.gov (United States)

    Erdmann, Simon E; Dietz, Rune; Sonne, Christian; Bechshøft, Thea Ø; Vorkamp, Katrin; Letcher, Robert J; Long, Manhai; Bonefeld-Jørgensen, Eva C

    2013-07-01

    The aims of the project were to (i) extract the lipophilic persistent organic pollutants (POPs) from the blood of 99 East Greenland polar bears and assess the combined mixture effect on the estrogen receptor (ER) and the aryl hydrocarbon receptor (AhR) mediated transactivity; (ii) To evaluate whether the receptor transactivities were associated with selected POP markers, and (iii) compare the receptor transactivities in polar bears with earlier studies on Greenlandic Inuit. Lipophilic POPs were extracted using a combination of solid-phase extraction (SPE) and high performance liquid chromatography (HPLC). ER mediated transactivity was determined using the ER luciferase reporter MVLN cell assay. The extracts were tested alone (XER) and together with 17β-estradiol (E2) as a physiological mimic (XERcomp). Dioxins and dioxin-like (DL) compounds were extracted by a combination of SPE and the Supelco Dioxin Prep System®. AhR mediated dioxin-like transactivity was determined using the AhR luciferase reporter Hepa 1.12cR cell assay. Agonistic ER transactivity was elicited by 19% of the samples, and a further increased E2 induced ER response was found for 52%, whereas 17% antagonized the E2 induced ER response. Positive correlations were found in subadult bears between XER and several POP biomarkers. XER and XERcomp correlated positively to each other. A total of 91% of the polar bear blood extracts elicited agonistic AhR transactivity. The AhR-TCDD equivalent (AhR-TEQ) median levels were higher among adult bears compared to subadult bears, but not significantly. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Rebuttal of "Polar bear population forecasts: a public-policy forecasting audit"

    Science.gov (United States)

    Amstrup, Steven C.; Caswell, Hal; DeWeaver, Eric; Stirling, Ian; Douglas, David C.; Marcot, Bruce G.; Hunter, Christine M.

    2009-01-01

    Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears (Ursus maritimus). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior's listing-decision process, the US Geological Survey (USGS) produced a series of nine research reports evaluating the present and future status of polar bears throughout their range. In response, Armstrong et al. [Armstrong, J. S., K. C. Green, W. Soon. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38(5) 382–405], which we will refer to as AGS, performed an audit of two of these nine reports. AGS claimed that the general circulation models upon which the USGS reports relied were not valid forecasting tools, that USGS researchers were not objective or lacked independence from policy decisions, that they did not utilize all available information in constructing their forecasts, and that they violated numerous principles of forecasting espoused by AGS. AGS (p. 382) concluded that the two USGS reports were "unscientific and inconsequential to decision makers." We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim. We provide evidence that general circulation models are useful in forecasting future climate conditions and that corporate and government leaders are relying on these models to do so. We clarify the strict independence of the USGS from the listing decision. We show that the allegations of failure to follow the principles of forecasting espoused by AGS are either incorrect or are based on misconceptions about the Arctic environment, polar bear biology, or statistical and mathematical methods. We conclude by showing that the AGS principles of forecasting are too ambiguous and subjective to be used as a reliable basis for auditing scientific

  3. Health effects from long-range transported contaminants in Arctic top predators: An integrated review based on studies of polar bears and relevant model species.

    Science.gov (United States)

    Sonne, Christian

    2010-07-01

    The aim of this review is to provide a thorough overview of the health effects from the complexed biomagnified mixture of long-range transported industrial organochlorines (OCs), polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs) and mercury (Hg) on polar bear (Ursus maritimus) health. Multiple scientific studies of polar bears indicate negative relationships between exposure to these contaminants and health parameters; however, these are all of a correlative nature and do not represent true cause-and-effects. Therefore, information from controlled studies of farmed Norwegian Arctic foxes (Vulpes lagopus) and housed East and West Greenland sledge dogs (Canis familiaris) were included as supportive weight of evidence in the clarification of contaminant exposure and health effects in polar bears. The review showed that hormone and vitamin concentrations, liver, kidney and thyroid gland morphology as well as reproductive and immune systems of polar bears are likely to be influenced by contaminant exposure. Furthermore, exclusively based on polar bear contaminant studies, bone density reduction and neurochemical disruption and DNA hypomethylation of the brain stem seemed to occur. The range of tissue concentration, at which these alterations were observed in polar bears, were ca. 1-70,000 ng/g lw for OCs (blood plasma concentrations of some PCB metabolites even higher), ca. 1-1000 ng/g lw for PBDEs and for PFCs and Hg 114-3052 ng/g ww and 0.1-50 microg/g ww, respectively. Similar concentrations were found in farmed foxes and housed sledge dogs while the lack of dose response designs did not allow an estimation of threshold levels for oral exposure and accumulated tissue concentrations. Nor was it possible to pinpoint a specific group of contaminants being more important than others nor analyze their interactions. For East Greenland polar bears the corresponding daily SigmaOC and SigmaPBDE oral exposure was estimated to be 35 and 0.34 microg/kg body

  4. Are organohalogen contaminants a cofactor in the development of renal lesions in east Greenland polar bears (Ursus maritimus)?

    Science.gov (United States)

    Sonne, Christian; Dietz, Rune; Leifsson, Pall S; Born, Erik W; Kirkegaard, Maja; Letcher, Robert J; Muir, Derek C G; Riget, Frank E; Hyldstrup, Lars

    2006-06-01

    Tissues of polar bears (Ursus maritimus) from East Greenland contain the highest concentrations of organohalogen contaminants (OHCs) among subpopulations of any mammalian species in the Arctic. Negative associations also have been found between OHC concentrations and bone mineral density and liver histology parameters for this subpopulation of polar bears. The present study examined the OHC concentrations and adverse effects on renal tissue for 75 polar bears collected during 1999 to 2002. Specific lesions were diffuse glomerular capillary wall thickening, mesangial glomerular deposits, tubular epithelial cell hyperplasia, hyalinization of the tubular basement membrane, tubular dilatation, atrophy and necrosis, tubular medullary hyalin casts, interstitial fibrosis, and mononuclear cell infiltration. With the exception of mononuclear cell infiltrations, all these parameters were correlated with age, whereas none was associated with the sex of the animals. In an age-controlled statistical analysis of covariance, increases in glomerular mesangial deposits and interstitial fibrosis were significantly (p < 0.05) correlated with polybrominated diphenyl ether (sigmaPBDE) concentrations in subadults. In adult males, statistically significant (p < 0.05) positive correlations were found for tubular epithelial cell hyperplasia and dieldrin concentration; diffuse glomerular capillary wall thickening and chlordane (sigmaCHL) concentrations, and tubular medullary hyalin casts and sigmaCHL, sigmaPBDE, polychlorinated biphenyl, and hexachlorocyclohexane concentrations. The lesions were consistent with those reported previously in highly OHC-contaminated Baltic seal populations and exposed laboratory animals. The renal lesions were a result of aging. However, based on the above statistical findings as well as the nature of the findings, we suggest that long-term exposure to OHCs may be a cofactor in renal lesion occurrence, although other cofactors, such as exposure to heavy metals

  5. The influence of climate variability on polar bear (Ursus maritimus) and ringed seal (Pusa hispida) population dynamics

    DEFF Research Database (Denmark)

    Rosing-Asvid, A.

    2006-01-01

    Unusually high polar bear (Ursus maritimus Phipps, 1774) predation on ringed seal (Pusa hispida (Schreber, 1775)) pups and increased survival of polar bear cubs during mild springs is documented in published articles. Strong predation on newborn ringed seal pups in early spring, however, is likely...... to lower the overall energy intake of polar bears if ringed seal pups are their main food, because the energetic value of ringed seal pups increases 7-8 times during the 6 week lactation period. So although hunting success in early spring increases cub survival during the period after den emergence......,when they are most vulnerable, it is likely to increase the number of starving bears later in the season. This negative-feedback effect of strong spring predation will not occur in areas where other seal species are abundant during summer, and polar bears in such areas are likely to exhibit population growth during...

  6. Geographical distribution of organochlorine pesticides (OCPs) in polar bears (Ursus maritimus) in the Norwegian and Russian Arctic.

    Science.gov (United States)

    Lie, E; Bernhoft, A; Riget, F; Belikov, S E; Boltunov, A N; Derocher, A E; Garner, G W; Wiig, Ø; Skaare, J U

    2003-05-01

    Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, alpha-HCH, beta-HCH and p,p'-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of alpha- and beta-HCH. The lowest alpha-HCH concentration was found in bears from Kara Sea. In all the bears, summation operator HCHs was dominated by beta-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p'-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research.

  7. Geographical distribution of organochlorine pesticides (OCPs) in polar bears (Ursus maritimus) in the Norwegian and Russian Arctic

    Science.gov (United States)

    Lie, E.; Bernhoft, A.; Riget, F.; Belikov, Stanislav; Boltunov, Andrei N.; Derocher, A.E.; Garner, G.W.; Wiig, O.; Skaare, J.U.

    2003-01-01

    Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, ??-HCH, ??-HCH and p,p???-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of ??- and ??-HCH. The lowest ??-HCH concentration was found in bears from Kara Sea. In all the bears, ???HCHs was dominated by ??-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p???-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research. ?? 2002 Elsevier Science B.V. All rights reserved.

  8. Hematology of southern Beaufort Sea polar bears (2005-2007): Biomarker for an arctic ecosystem health sentinel

    Science.gov (United States)

    Kirk, Cassandra M.; Amstrup, Steven C.; Swor, Rhonda; Holcomb, Darce; O'Hara, T. M.

    2010-01-01

    Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ???5, than lactating adult females ages ???5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel. ?? 2010 International Association for Ecology and Health.

  9. Environmental contaminants activate human and polar bear (Ursus maritimus) pregnane X receptors (PXR, NR1I2) differently

    International Nuclear Information System (INIS)

    Lille-Langøy, Roger; Goldstone, Jared V.; Rusten, Marte; Milnes, Matthew R.; Male, Rune; Stegeman, John J.; Blumberg, Bruce; Goksøyr, Anders

    2015-01-01

    Background: Many persistent organic pollutants (POPs) accumulate readily in polar bears because of their position as apex predators in Arctic food webs. The pregnane X receptor (PXR, formally NR1I2, here proposed to be named promiscuous xenobiotic receptor) is a xenobiotic sensor that is directly involved in metabolizing pathways of a wide range of environmental contaminants. Objectives: In the present study, we comparably assess the ability of 51 selected pharmaceuticals, pesticides and emerging contaminants to activate PXRs from polar bears and humans using an in vitro luciferase reporter gene assay. Results: We found that polar bear PXR is activated by a wide range of our test compounds (68%) but has a slightly more narrow ligand specificity than human PXR that was activated by 86% of the 51 test compounds. The majority of the agonists identified (70%) produces a stronger induction of the reporter gene via human PXR than via polar bear PXR, however with some notable and environmentally relevant exceptions. Conclusions: Due to the observed differences in activation of polar bear and human PXRs, exposure of each species to environmental agents is likely to induce biotransformation differently in the two species. Bioinformatics analyses and structural modeling studies suggest that amino acids that are not part of the ligand-binding domain and do not interact with the ligand can modulate receptor activation. - Highlights: • Comparative study of ligand activation of human and polar bear PXRs. • Polar bear PXR is a promiscuous ligand-activated nuclear receptor but less so than human PXR. • Environmental contaminants activate human and polar bear PXRs differently. • Expression and ligand promiscuity indicate that PXR is a xenosensor in polar bears

  10. Hematology of southern Beaufort Sea polar bears (2005-2007): biomarker for an Arctic ecosystem health sentinel.

    Science.gov (United States)

    Kirk, Cassandra M; Amstrup, Steven; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M

    2010-09-01

    Declines in sea-ice habitats have resulted in declining stature, productivity, and survival of polar bears in some regions. With continuing sea-ice declines, negative population effects are projected to expand throughout the polar bear's range. Precise causes of diminished polar bear life history performance are unknown, however, climate and sea-ice condition change are expected to adversely impact polar bear (Ursus maritimus) health and population dynamics. As apex predators in the Arctic, polar bears integrate the status of lower trophic levels and are therefore sentinels of ecosystem health. Arctic residents feed at the apex of the ecosystem, thus polar bears can serve as indicators of human health in the Arctic. Despite their value as indicators of ecosystem welfare, population-level health data for U.S. polar bears are lacking. We present hematological reference ranges for southern Beaufort Sea polar bears. Hematological parameters in southern Beaufort Sea polar bears varied by age, geographic location, and reproductive status. Total leukocytes, lymphocytes, monocytes, eosinophils, and serum immunoglobulin G were significantly greater in males than females. These measures were greater in nonlactating females ages ≥5, than lactating adult females ages ≥5, suggesting that females encumbered by young may be less resilient to new immune system challenges that may accompany ongoing climate change. Hematological values established here provide a necessary baseline for anticipated changes in health as arctic temperatures warm and sea-ice declines accelerate. Data suggest that females with dependent young may be most vulnerable to these changes and should therefore be a targeted cohort for monitoring in this sentinel.

  11. Environmental contaminants activate human and polar bear (Ursus maritimus) pregnane X receptors (PXR, NR1I2) differently

    Energy Technology Data Exchange (ETDEWEB)

    Lille-Langøy, Roger, E-mail: Roger.lille-langoy@bio.uib.no [University of Bergen, Department of Biology, P.O. Box 7803, N-5020 Bergen (Norway); Goldstone, Jared V. [Woods Hole Oceanographic Institution, 266 Woods Hole Road, 02543-1050 Woods Hole, MA (United States); Rusten, Marte [University of Bergen, Department of Molecular Biology, P.O. Box 7803, N-5020 Bergen (Norway); Milnes, Matthew R. [Mars Hill University, 100 Athletic Street, Box 6671, Mars Hill, 28754 NC (United States); Male, Rune [University of Bergen, Department of Molecular Biology, P.O. Box 7803, N-5020 Bergen (Norway); Stegeman, John J. [Woods Hole Oceanographic Institution, 266 Woods Hole Road, 02543-1050 Woods Hole, MA (United States); Blumberg, Bruce [University of California, Irvine, 92697 CA (United States); Goksøyr, Anders [University of Bergen, Department of Biology, P.O. Box 7803, N-5020 Bergen (Norway)

    2015-04-01

    Background: Many persistent organic pollutants (POPs) accumulate readily in polar bears because of their position as apex predators in Arctic food webs. The pregnane X receptor (PXR, formally NR1I2, here proposed to be named promiscuous xenobiotic receptor) is a xenobiotic sensor that is directly involved in metabolizing pathways of a wide range of environmental contaminants. Objectives: In the present study, we comparably assess the ability of 51 selected pharmaceuticals, pesticides and emerging contaminants to activate PXRs from polar bears and humans using an in vitro luciferase reporter gene assay. Results: We found that polar bear PXR is activated by a wide range of our test compounds (68%) but has a slightly more narrow ligand specificity than human PXR that was activated by 86% of the 51 test compounds. The majority of the agonists identified (70%) produces a stronger induction of the reporter gene via human PXR than via polar bear PXR, however with some notable and environmentally relevant exceptions. Conclusions: Due to the observed differences in activation of polar bear and human PXRs, exposure of each species to environmental agents is likely to induce biotransformation differently in the two species. Bioinformatics analyses and structural modeling studies suggest that amino acids that are not part of the ligand-binding domain and do not interact with the ligand can modulate receptor activation. - Highlights: • Comparative study of ligand activation of human and polar bear PXRs. • Polar bear PXR is a promiscuous ligand-activated nuclear receptor but less so than human PXR. • Environmental contaminants activate human and polar bear PXRs differently. • Expression and ligand promiscuity indicate that PXR is a xenosensor in polar bears.

  12. Per- and polyfluoroalkyl substances (PFASs) – New endocrine disruptors in polar bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Pedersen, Kathrine Eggers; Letcher, Robert J.; Sonne, Christian

    2016-01-01

    Per- and polyfluoroalkyl substances (PFASs) are emerging in the Arctic and accumulate in brain tissues of East Greenland (EG) polar bears. In vitro studies have shown that PFASs might possess endocrine disrupting abilities and therefore the present study was conducted to investigate potential PFAS...... induced alterations in brain steroid concentrations. The concentrations of eleven steroid hormones were determined in eight brain regions from ten EG polar bears. Pregnenolone (PRE), the dominant progestagen, was found in mean concentrations of 5-47ng/g (ww) depending on brain region. PRE showed...... significantly (pbears. Dehydroepiandrosterone (DHEA) found in mean concentrations 0.67-4.58ng/g (ww) was the androgen found in highest concentrations. Among the estrogens estrone (E1) showed mean concentrations of 0.90-2.21ng/g (ww) and was the most...

  13. Monitoring the welfare of polar bear populations in a rapidly changing Arctic

    Science.gov (United States)

    Atwood, Todd C.; Duncan, Colleen G.; Patyk, Kelly A.; Sonsthagen, Sarah A.

    2017-01-01

    Most programs for monitoring the welfare of wildlife populations support efforts aimed at reaching discrete management objectives, like mitigating conflict with humans. While such programs can be effective, their limited scope may preclude systemic evaluations needed for large-scale conservation initiatives, like the recovery of at-risk species. We discuss select categories of metrics that can be used to monitor how polar bears (Ursus maritimus) are responding to the primary threat to their long-term persistence—loss of sea ice habitat due to the unabated rise in atmospheric greenhouse gas (GHG; e.g., CO2) concentrations—that can also provide information on ecosystem function and health. Monitoring key aspects of polar bear population dynamics, spatial behavior, health and resiliency can provide valuable insight into ecosystem state and function, and could be a powerful tool for achieving Arctic conservation objectives, particularly those that have transnational policy implications.

  14. Polar bear population status in the northern Beaufort Sea, Canada, 1971-2006

    Science.gov (United States)

    Stirling, I.; McDonald, T.L.; Richardson, E.S.; Regehr, E.V.; Amstrup, Steven C.

    2011-01-01

    Polar bears (Ursus maritimus) of the northern Beaufort Sea (NB) population occur on the perimeter of the polar basin adjacent to the northwestern islands of the Canadian Arctic Archipelago. Sea ice converges on the islands through most of the year. We used open-population capture–recapture models to estimate population size and vital rates of polar bears between 1971 and 2006 to: (1) assess relationships between survival, sex and age, and time period; (2) evaluate the long-term importance of sea ice quality and availability in relation to climate warming; and (3) note future management and conservation concerns. The highest-ranking models suggested that survival of polar bears varied by age class and with changes in the sea ice habitat. Model-averaged estimates of survival (which include harvest mortality) for senescent adults ranged from 0.37 to 0.62, from 0.22 to 0.68 for cubs of the year (COY) and yearlings, and from 0.77 to 0.92 for 2–4 year-olds and adults. Horvtiz-Thompson (HT) estimates of population size were not significantly different among the decades of our study. The population size estimated for the 2000s was 980 ± 155 (mean and 95% CI). These estimates apply primarily to that segment of the NB population residing west and south of Banks Island. The NB polar bear population appears to have been stable or possibly increasing slightly during the period of our study. This suggests that ice conditions have remained suitable and similar for feeding in summer and fall during most years and that the traditional and legal Inuvialuit harvest has not exceeded sustainable levels. However, the amount of ice remaining in the study area at the end of summer, and the proportion that continues to lie over the biologically productive continental shelf (Sea will eventually decline. Management and conservation practices for polar bears in relation to both aboriginal harvesting and offshore industrial activity will need to adapt.

  15. Tracheitis associated with Bordetella bronchiseptica in a polar bear (Ursus maritimus).

    Science.gov (United States)

    Lacasse, Claude; Gamble, Kathryn C

    2006-06-01

    A male polar bear (Ursus maritimus) was diagnosed with tracheitis associated with Bordetella bronchiseptica that was cultured from an endotracheal sample of thick mucopurulent exudate. The condition responded to oral amoxicillin/clavulanic acid, and clinical signs of inappetence, depression, dysphagia, and tussis were resolved. One week after this presentation, a female conspecific presented with similar clinical signs, suggesting a transmissible nature of the disease or the same source of infection. The source of infection remains unknown.

  16. Brucella species survey in polar bears (ursus maritimus) of northern Alaska.

    Science.gov (United States)

    O'Hara, Todd M; Holcomb, Darce; Elzer, Philip; Estepp, Jessica; Perry, Quinesha; Hagius, Sue; Kirk, Cassandra

    2010-07-01

    We report on the presence of specific antibodies to Brucella spp. and Yersinia enterocolitica in polar bears (Ursus maritimus) from northern Alaska (southern Beaufort Sea) during 2003-2006. Based on numerous known stressors (e.g., climate change and loss of sea ice habitat, contaminants), there is increased concern regarding the status of polar bears. Considering these changes, it is important to assess exposure to potentially pathogenic organisms and to improve understanding of transmission pathways. Brucella or specific antibodies to Brucella spp. has been reported in marine mammals. Various assays were used to elucidate the pathway or source of exposure (e.g., "marine" vs. "terrestrial" Brucella spp.) of northern Alaska polar bears to Brucella spp. The standard plate test (SPT) and the buffered Brucella antigen card test (BBA) were used for initial screening for antibodies specific to Brucella. We then evaluated positive reactors (presence of serum antibody specific for Brucella spp.) using immunoblots and competitive enzyme-linked immunosorbent assay (cELISA; based on pinniped-derived Brucella spp. antigen). Annual prevalence of antibody (BBA and SPT) for Brucella spp. ranged from 6.8% to 18.5% over 2003-2006, with an overall prevalence of 10.2%. Prevalence of Brucella spp. antibody did vary by age class. Western blot analyses indicated 17 samples were positive for Brucella spp. antibody; of these, 13 were negative by marine (pinniped) derived Brucella antigen cELISA and four were positive by marine cELISA. Of the four samples positive for Brucella antibody by marine cELISA, three cross-reacted with Y. enterocolitica and Brucella spp. (one sample was Brucella negative and Y. enterocolitica positive). It appears the polar bear antibody does not react with the antigens used on the marine cELISA assay, potentially indicating a terrestrial (nonpinniped) source of Brucella spp.

  17. Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy

    OpenAIRE

    Harvey, Jeffrey A.; van den Berg, Daphne; Ellers, Jacintha; Kampen, Remko; Crowther, Thomas W.; Roessingh, Peter; Verheggen, Bart; Nuijten, Rascha J. M.; Post, Eric; Lewandowsky, Stephan; Stirling, Ian; Balgopal, Meena; Amstrup, Steven C.; Mann, Michael E.

    2017-01-01

    Increasing surface temperatures, Arctic sea-ice loss, and other evidence of anthropogenic global warming (AGW) are acknowledged by every major scientific organization in the world. However, there is a wide gap between this broad scientific consensus and public opinion. Internet blogs have strongly contributed to this consensus gap by fomenting misunderstandings of AGW causes and consequences. Polar bears (Ursus maritimus) have become a “poster species” for AGW, making them a target of those d...

  18. Demographic and traditional knowledge perspectives on the current status of Canadian polar bear subpopulations.

    Science.gov (United States)

    York, Jordan; Dowsley, Martha; Cornwell, Adam; Kuc, Miroslaw; Taylor, Mitchell

    2016-05-01

    Subpopulation growth rates and the probability of decline at current harvest levels were determined for 13 subpopulations of polar bears (Ursus maritimus) that are within or shared with Canada based on mark-recapture estimates of population numbers and vital rates, and harvest statistics using population viability analyses (PVA). Aboriginal traditional ecological knowledge (TEK) on subpopulation trend agreed with the seven stable/increasing results and one of the declining results, but disagreed with PVA status of five other declining subpopulations. The decline in the Baffin Bay subpopulation appeared to be due to over-reporting of harvested numbers from outside Canada. The remaining four disputed subpopulations (Southern Beaufort Sea, Northern Beaufort Sea, Southern Hudson Bay, and Western Hudson Bay) were all incompletely mark-recapture (M-R) sampled, which may have biased their survival and subpopulation estimates. Three of the four incompletely sampled subpopulations were PVA identified as nonviable (i.e., declining even with zero harvest mortality). TEK disagreement was nonrandom with respect to M-R sampling protocols. Cluster analysis also grouped subpopulations with ambiguous demographic and harvest rate estimates separately from those with apparently reliable demographic estimates based on PVA probability of decline and unharvested subpopulation growth rate criteria. We suggest that the correspondence between TEK and scientific results can be used to improve the reliability of information on natural systems and thus improve resource management. Considering both TEK and scientific information, we suggest that the current status of Canadian polar bear subpopulations in 2013 was 12 stable/increasing and one declining (Kane Basin). We do not find support for the perspective that polar bears within or shared with Canada are currently in any sort of climate crisis. We suggest that monitoring the impacts of climate change (including sea ice decline) on polar bear

  19. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears

    Science.gov (United States)

    Atwood, Todd C.; Marcot, Bruce G.; Douglas, David C.; Amstrup, Steven C.; Rode, Karyn D.; Durner, George M.; Bromaghin, Jeffrey F.

    2016-01-01

    Effective conservation planning requires understanding and ranking threats to wildlife populations. We developed a Bayesian network model to evaluate the relative influence of environmental and anthropogenic stressors, and their mitigation, on the persistence of polar bears (Ursus maritimus). Overall sea ice conditions, affected by rising global temperatures, were the most influential determinant of population outcomes. Accordingly, unabated rise in atmospheric greenhouse gas (GHG) concentrations was the dominant influence leading to worsened population outcomes, with polar bears in three of four ecoregions reaching a dominant probability of decreased or greatly decreased by the latter part of this century. Stabilization of atmospheric GHG concentrations by mid-century delayed the greatly reduced state by ≈25 yr in two ecoregions. Prompt and aggressive mitigation of emissions reduced the probability of any regional population becoming greatly reduced by up to 25%. Marine prey availability, linked closely to sea ice trend, had slightly less influence on outcome state than sea ice availability itself. Reduced mortality from hunting and defense of life and property interactions resulted in modest declines in the probability of a decreased or greatly decreased population outcome. Minimizing other stressors such as trans-Arctic shipping, oil and gas exploration, and contaminants had a negligible effect on polar bear outcomes, although the model was not well-informed with respect to the potential influence of these stressors. Adverse consequences of loss of sea ice habitat became more pronounced as the summer ice-free period lengthened beyond four months, which could occur in most of the Arctic basin after mid-century if GHG emissions are not promptly reduced. Long-term conservation of polar bears would be best supported by holding global mean temperature to ≤ 2°C above preindustrial levels. Until further sea ice loss is stopped, management of other stressors may

  20. Assessing polar bear (Ursus maritimus) population structure in the Hudson Bay region using SNPs.

    Science.gov (United States)

    Viengkone, Michelle; Derocher, Andrew Edward; Richardson, Evan Shaun; Malenfant, René Michael; Miller, Joshua Moses; Obbard, Martyn E; Dyck, Markus G; Lunn, Nick J; Sahanatien, Vicki; Davis, Corey S

    2016-12-01

    Defining subpopulations using genetics has traditionally used data from microsatellite markers to investigate population structure; however, single-nucleotide polymorphisms (SNPs) have emerged as a tool for detection of fine-scale structure. In Hudson Bay, Canada, three polar bear ( Ursus maritimus ) subpopulations (Foxe Basin (FB), Southern Hudson Bay (SH), and Western Hudson Bay (WH)) have been delineated based on mark-recapture studies, radiotelemetry and satellite telemetry, return of marked animals in the subsistence harvest, and population genetics using microsatellites. We used SNPs to detect fine-scale population structure in polar bears from the Hudson Bay region and compared our results to the current designations using 414 individuals genotyped at 2,603 SNPs. Analyses based on discriminant analysis of principal components (DAPC) and STRUCTURE support the presence of four genetic clusters: (i) Western-including individuals sampled in WH, SH (excluding Akimiski Island in James Bay), and southern FB (south of Southampton Island); (ii) Northern-individuals sampled in northern FB (Baffin Island) and Davis Strait (DS) (Labrador coast); (iii) Southeast-individuals from SH (Akimiski Island in James Bay); and (iv) Northeast-individuals from DS (Baffin Island). Population structure differed from microsatellite studies and current management designations demonstrating the value of using SNPs for fine-scale population delineation in polar bears.

  1. Remote identification of maternal polar bear (Ursus maritimus) denning habitat on the Colville River Delta, Alaska

    Science.gov (United States)

    Blank, Justin J.

    High resolution digital aerial photographs (1 foot pixel size) of the Colville River Delta, Alaska were examined in 3D, with the use of a digital photogrammetric workstation. Topographic features meeting the criteria required for adequate snow accumulation, and subsequent construction of terrestrial polar bear maternal dens, were identified and digitized into an ArcGIS line shapefile. Effectiveness, efficiency, and accuracy were improved when compared to previous polar bear denning habitat efforts which utilized contact photo prints and a pocket stereoscope in other geographic areas of northern Alaska. Accuracy of photograph interpretation was systematically evaluated visually from the air with the use of a helicopter and physically on the ground. Results show that the mapping efforts were successful in identifying den habitat 91.3% of the time. Knowledge denning habitat can improve and inform decision making by managers and regulators when considering travel and development in the study area. An understanding of polar bear denning habitat extent and location will be a crucial tool for planning activities within the study area in a way that minimizes conflicts with maternal dens.

  2. Using simulation to evaluate wildlife survey designs: polar bears and seals in the Chukchi Sea.

    Science.gov (United States)

    Conn, Paul B; Moreland, Erin E; Regehr, Eric V; Richmond, Erin L; Cameron, Michael F; Boveng, Peter L

    2016-01-01

    Logistically demanding and expensive wildlife surveys should ideally yield defensible estimates. Here, we show how simulation can be used to evaluate alternative survey designs for estimating wildlife abundance. Specifically, we evaluate the potential of instrument-based aerial surveys (combining infrared imagery with high-resolution digital photography to detect and identify species) for estimating abundance of polar bears and seals in the Chukchi Sea. We investigate the consequences of different levels of survey effort, flight track allocation and model configuration on bias and precision of abundance estimators. For bearded seals (0.07 animals km(-2)) and ringed seals (1.29 animals km(-2)), we find that eight flights traversing ≈7840 km are sufficient to achieve target precision levels (coefficient of variation (CV)polar bears (provisionally, 0.003 animals km(-2)), 12 flights traversing ≈11 760 km resulted in CVs ranging from 28 to 35%. Estimators were relatively unbiased with similar precision over different flight track allocation strategies and estimation models, although some combinations had superior performance. These findings suggest that instrument-based aerial surveys may provide a viable means for monitoring seal and polar bear populations on the surface of the sea ice over large Arctic regions. More broadly, our simulation-based approach to evaluating survey designs can serve as a template for biologists designing their own surveys.

  3. Thermospheric density structures over the polar regions observed with CHAMP

    Directory of Open Access Journals (Sweden)

    K. Schlegel

    2005-07-01

    Full Text Available We report on the unexpected detection of considerable structure in high latitude thermospheric densities, as derived from an accelerometer onboard the CHAMP satellite. The width of the structures, which can either be maxima or minima, varies between a few hundred km and 2000 km. The amplitudes of these density extrema can reach 50% of ambient. Maxima cluster around 75° (N and S, while minima are found closer to the poles. In a magnetic latitude-magnetic local time frame the maxima are found mainly around the cusp region. Overall, the observed structures somewhat resemble so-called density cells previously found in model calculations. However the models generate their cells around 140–300 km altitude and show little, if any remnant at 400 km or above. This has to be contrasted with the fact that the CHAMP observations were obtained near 430 km altitude. We have explored Joule heating as a possible mechanism for the generation of the structures, at least in density enhancement regions, using Hall currents measured on CHAMP and simultaneous incoherent scatter measurements with EISCAT. However, the electric fields were usually quite small during the period of observation, making the quest for an explanation for the structures all the more challenging. Keywords. Meteorology and atmospheric dynamics (Thermospheric dynamics – Magnetospheric physics (Polar cap phenomena – Atmospheric composition and structure (Pressure, density, and temperature

  4. Serosurvey for Trichinella in polar bears (Ursus maritimus) from Svalbard and the Barents Sea.

    Science.gov (United States)

    Asbakk, Kjetil; Aars, Jon; Derocher, Andrew E; Wiig, Oystein; Oksanen, Antti; Born, Erik W; Dietz, Rune; Sonne, Christian; Godfroid, Jacques; Kapel, Christian M O

    2010-09-20

    Blood samples of live-caught polar bears (Ursus maritimus) from Svalbard collected 1991-2000 (Period 1) and 2006-2008 (Period 2) and from the pack ice of the Barents Sea collected in Period 1, were assayed for antibodies against Trichinella spp. by ELISA. Of 54 cubs-of-the-year included in the Period 1 sample, 53 were seronegative, indicating that exposure to Trichinella infected meat is uncommon during the first months of life for polar bears in the Svalbard region. Of 30 mother-offspring pairs, 18 mothers were seropositive with seronegative offspring (n=27), suggesting (1) that maternal antibodies had dropped to levels below detection limit by the time of capture in April (offspring approximately 4 months old), and (2) supporting experimental studies in other animal models showing that vertical transmission of Trichinella spp. is uncommon. Bear 1 year and older had higher prevalence in Svalbard (78%) than in the Barents Sea (51%). There was no temporal change in prevalence for bears from Svalbard during the time between the two periods. The prevalence increased with age in both sexes. A positive correlation was found between anti-Toxoplasma gondii and anti-Trichinella spp. antibodies.

  5. Molecular density functional theory of water including density–polarization coupling

    OpenAIRE

    Jeanmairet, Guillaume; Lévy, Nicolas; Levesque, Maximilien; Borgis, Daniel

    2016-01-01

    International audience; We present a three-dimensional molecular density functional theory of water derived fromfirst-principles that relies on the particle’s density and multipolar polarization density andincludes the density–polarization coupling. This brings two main benefits: (i) scalar densityand vectorial multipolar polarization density fields are much more tractable and give morephysical insight than the full position and orientation densities, and (ii) it includes the fulldensity–pola...

  6. Influence of carbon and lipid sources on variation of mercury and other trace elements in polar bears (Ursus maritimus).

    Science.gov (United States)

    Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; McKinney, Melissa A; Peacock, Elizabeth; Sonne, Christian

    2012-12-01

    In the present study, the authors investigated the influence of carbon and lipid sources on regional differences in liver trace element (As, Cd, Cu, total Hg, Mn, Pb, Rb, Se, and Zn) concentrations measured in polar bears (Ursus maritimus) (n = 121) from 10 Alaskan, Canadian Arctic, and East Greenland subpopulations. Carbon and lipid sources were assessed using δ(13) C in muscle tissue and fatty acid (FA) profiles in subcutaneous adipose tissue as chemical tracers. A negative relationship between total Hg and δ(13) C suggested that polar bears feeding in areas with higher riverine inputs of terrestrial carbon accumulate more Hg than bears feeding in areas with lower freshwater input. Mercury concentrations were also positively related to the FA 20:1n-9, which is biosynthesized in large amounts in Calanus copepods. This result raises the hypothesis that Calanus glacialis are an important link in the uptake of Hg in the marine food web and ultimately in polar bears. Unadjusted total Hg, Se, and As concentrations showed greater geographical variation among polar bear subpopulations compared with concentrations adjusted for carbon and lipid sources. The Hg concentrations adjusted for carbon and lipid sources in Bering-Chukchi Sea polar bear liver tissue remained the lowest among subpopulations. Based on these findings, the authors suggest that carbon and lipid sources for polar bears should be taken into account when one is assessing spatial and temporal trends of long-range transported trace elements. Copyright © 2012 SETAC.

  7. Costs of locomotion in polar bears: when do the costs outweigh the benefits of chasing down terrestrial prey?

    Science.gov (United States)

    Gormezano, Linda J; McWilliams, Scott R; Iles, David T; Rockwell, Robert F

    2016-01-01

    Trade-offs between locomotory costs and foraging gains are key elements in determining constraints on predator-prey interactions. One intriguing example involves polar bears pursuing snow geese on land. As climate change forces polar bears to spend more time ashore, they may need to expend more energy to obtain land-based food. Given that polar bears are inefficient at terrestrial locomotion, any extra energy expended to pursue prey could negatively impact survival. However, polar bears have been regularly observed engaging in long pursuits of geese and other land animals, and the energetic worth of such behaviour has been repeatedly questioned. We use data-driven energetic models to examine how energy expenditures vary across polar bear mass and speed. For the first time, we show that polar bears in the 125-235 kg size range can profitably pursue geese, especially at slower speeds. We caution, however, that heat build-up may be the ultimate limiting factor in terrestrial chases, especially for larger bears, and this limit would be reached more quickly with warmer environmental temperatures.

  8. Dietary composition and spatial patterns of polar bear foraging on land in western Hudson Bay.

    Science.gov (United States)

    Gormezano, Linda J; Rockwell, Robert F

    2013-12-21

    Flexible foraging strategies, such as prey switching, omnivory and food mixing, are key to surviving in a labile and changing environment. Polar bears (Ursus maritimus) in western Hudson Bay are versatile predators that use all of these strategies as they seasonally exploit resources across trophic levels. Climate warming is reducing availability of their ice habitat, especially in spring when polar bears gain most of their annual fat reserves by consuming seal pups before coming ashore in summer. How polar bears combine these flexible foraging strategies to obtain and utilize terrestrial food will become increasingly important in compensating for energy deficits from lost seal hunting opportunities. We evaluated patterns in the composition of foods in scat to characterize the foraging behaviors that underpin the diet mixing and omnivory observed in polar bears on land in western Hudson Bay. Specifically, we measured diet richness, proportions of plant and animal foods, patterns in co-occurrence of foods, spatial composition and an index of temporal composition. Scats contained between 1 and 6 foods, with an average of 2.11 (SE = 0.04). Most scats (84.9%) contained at least one type of plant, but animals (35.4% of scats) and both plants and animals occurring together (34.4% of scats) were also common. Certain foods, such as Lyme grass seed heads (Leymus arenarius), berries and marine algae, were consumed in relatively higher proportions, sometimes to the exclusion of others, both where and when they occurred most abundantly. The predominance of localized vegetation in scats suggests little movement among habitat types between feeding sessions. Unlike the case for plants, no spatial patterns were found for animal remains, likely due the animals' more vagile and ubiquitous distribution. Our results suggest that polar bears are foraging opportunistically in a manner consistent with maximizing intake while minimizing energy expenditure associated with movement. The

  9. Dental and Temporomandibular Joint Pathology of the Polar Bear (Ursus maritimus).

    Science.gov (United States)

    Winer, J N; Arzi, B; Leale, D M; Kass, P H; Verstraete, F J M

    2016-01-01

    Museum specimens (maxillae and/or mandibles) from 317 polar bears (Ursus maritimus) were examined macroscopically according to predefined criteria and 249 specimens were included in this study. The specimens were acquired between 1906 and 2011. There were 126 specimens (50.6%) from male animals, 93 (37.3%) from female animals and 30 (12.1%) from animals of unknown sex. The ages of the animals ranged from neonate to adult, with 125 adults (50.2%) and 124 young adults (49.8%) included and neonates/juveniles excluded from the study. The number of teeth available for examination was 7,638 (73.5%); 12.3% of teeth were absent artefactually, 0.8% were deemed absent due to acquired tooth loss and 13.4% were absent congenitally. With respect to tooth morphology, 20 teeth (0.26% of available teeth) in 18 specimens (7.2% of available specimens) were small vestigial structures with crowns that were flush with the level of surrounding alveolar bone. One supernumerary tooth and one tooth with enamel hypoplasia were encountered. Persistent deciduous teeth and teeth with an aberrant number of roots were not found. Relatively few teeth (3.7%) displayed attrition/abrasion, 90% of which were the maxillary and mandibular incisor teeth, in 41 polar bears (16.5%). Nearly twice as many adult specimens exhibited attrition/abrasion as those from young adults; significantly more males were affected than females. Dental fractures were noted in 52 polar bears, affecting 20.9% of specimens and 1.3% of the total number of teeth present. More adult polar bears had dental fractures than young adults. There were 21 specimens (8.4%) that displayed overt periapical disease, affecting a total of 24 dental alveoli (0.23%). Some degree of periodontitis was seen in 199 specimens (79.9%); however, only 12.6% of dental alveoli had bony changes indicative of periodontitis. Lesions consistent with temporomandibular joint osteoarthritis (TMJ-OA) were found in 23 specimens (9.2%). TMJ-OA was significantly

  10. DNA-based population density estimation of black bear at northern ...

    African Journals Online (AJOL)

    The analysis of deoxyribonucleic acid (DNA) microsatellites from hair samples obtained by the non-invasive method of traps was used to estimate the population density of black bears (Ursus americanus eremicus) in a mountain located at the county of Lampazos, Nuevo Leon, Mexico. The genotyping of bears was ...

  11. DNA-based population density estimation of black bear at northern ...

    African Journals Online (AJOL)

    UANL

    Studies performed in this place from 1991 to. 1994 indicate that the subspecies eremicus is very abundant and the estimated population density was as high as 0.72 bears /km2, although other studies using a different methodology calculated this value in 0.31 bears/km2 (Doan-Crider, 1995; Doan-Crider and Hewitt, ...

  12. A novel method for analysing key corticosteroids in polar bear (Ursus maritimus) hair using liquid chromatography tandem mass spectrometry

    DEFF Research Database (Denmark)

    Weisser, Johan; Hansen, Martin; Björklund, Erland

    2016-01-01

    This paper presents the development and evaluation of a methodology for extraction, clean-up and analysis of three key corticosteroids (aldosterone, cortisol and corticosterone) in polar bear hair. Such a methodology can be used to monitor stress biomarkers in polar bears and may provide....... This procedure allows for the simultaneous determination of multiple steroids, which is in contrast to previous polar bear studies based on ELISA techniques. Absolute method recoveries were 81%, 75% and 60% for cortisol, corticosterone and aldosterone, respectively. We applied the developed method on a hair...... sample pooled from four East Greenland polar bears. Herein cortisol and corticosterone were successfully determined in levels of 0.32±0.02ng/g hair and 0.13±0.02ng/g hair, respectively. Aldosterone was below limit of detection (LOD

  13. Possible effects of climate warming on selected populations of polar bears (Ursus maritimus) in the Canadian Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, I. [Canadian Wildlife Service, Edmonton, AB (Canada); Parkinson, C.L. [NASA Goddard Space Flight Center, Greenbelt, MD (United States). Cryospheric Sciences Branch

    2006-09-15

    Climate warming in the Arctic has caused declines in the total cover and thickness of sea ice. Intuit hunters in the areas of some polar bear populations in the eastern Canadian Arctic have noted that more bears have approached human settlements during open-water periods in recent years. The observations have been interpreted as evidence of increasing polar bear population size, and have resulted in increases in hunting quotas. However, research on 2 polar bear populations in Western Hudson Bay and Baffin Bay suggest that their numbers are declining. This paper evaluated patterns of sea-ice breakup and freeze-up in 5 regions to test the hypothesis that sightings of more polar bears are due in part to changes in sea ice. The regions were based on the accepted boundaries of the polar bear management zones used by government agencies in Canada and Greenland. Areas included Foxe Basin; Baffin Bay; Davis Strait; Hudson Strait; and Eastern Hudson Bay. Analysis of passive-microwave satellite imagery beginning in the 1970s has indicated that sea ice is breaking up at progressively earlier dates, so that bears must fast for longer periods during the open-water periods. This paper suggested that polar bears are being observed close to human settlements as they are searching for alternative food sources in years when their stored body fat is depleted before freeze-up, when they can return to the sea ice to hunt for seals. It was suggested that if the climate continues to warm as projected by the Intergovernmental Panel on Climate Change, polar bears in all 5 populations discussed in the paper will become increasingly food-stressed, and that their numbers are likely to decline. It was suggested that problem interactions between bears and humans will also increase as the bears seek alternative food sources. It was concluded that a precautionary approach should be taken to the harvesting of polar bears. The potential effects of climate warming should be incorporated into

  14. Simulating polar bear energetics during a seasonal fast using a mechanistic model.

    Directory of Open Access Journals (Sweden)

    Paul D Mathewson

    Full Text Available In this study we tested the ability of a mechanistic model (Niche Mapper™ to accurately model adult, non-denning polar bear (Ursus maritimus energetics while fasting during the ice-free season in the western Hudson Bay. The model uses a steady state heat balance approach, which calculates the metabolic rate that will allow an animal to maintain its core temperature in its particular microclimate conditions. Predicted weight loss for a 120 day fast typical of the 1990s was comparable to empirical studies of the population, and the model was able to reach a heat balance at the target metabolic rate for the entire fast, supporting use of the model to explore the impacts of climate change on polar bears. Niche Mapper predicted that all but the poorest condition bears would survive a 120 day fast under current climate conditions. When the fast extended to 180 days, Niche Mapper predicted mortality of up to 18% for males. Our results illustrate how environmental conditions, variation in animal properties, and thermoregulation processes may impact survival during extended fasts because polar bears were predicted to require additional energetic expenditure for thermoregulation during a 180 day fast. A uniform 3°C temperature increase reduced male mortality during a 180 day fast from 18% to 15%. Niche Mapper explicitly links an animal's energetics to environmental conditions and thus can be a valuable tool to help inform predictions of climate-related population changes. Since Niche Mapper is a generic model, it can make energetic predictions for other species threatened by climate change.

  15. The utility of harvest recoveries of marked individuals to assess polar bear (Ursus maritimus) survival

    Science.gov (United States)

    Peacock, Elizabeth; Laake, Jeff; Laidre, Kristin L.; Born, Erik W.; Atkinson, Stephen N.

    2012-01-01

    Management of polar bear (Ursus maritimus) populations requires the periodic assessment of life history metrics such as survival rate. This information is frequently obtained during short-term capture and marking efforts (e.g., over the course of three years) that result in hundreds of marked bears remaining in the population after active marking is finished. Using 10 additional years of harvest recovery subsequent to a period of active marking, we provide updated estimates of annual survival for polar bears in the Baffin Bay population of Greenland and Canada. Our analysis suggests a decline in survival of polar bears since the period of active marking that ended in 1997; some of the decline in survival can likely be attributed to a decline in springtime ice concentration over the continental shelf of Baffin Island. The variance around the survival estimates is comparatively high because of the declining number of marks available; therefore, results must be interpreted with caution. The variance of the estimates of survival increased most substantially in the sixth year post-marking. When survival estimates calculated with recovery-only and recapture-recovery data sets from the period of active marking were compared, survival rates were indistinguishable. However, for the period when fewer marks were available, survival estimates were lower using the recovery-only data set, which indicates that part of the decline we detected for 2003 – 09 may be due to using only harvest recovery data. Nevertheless, the decline in the estimates of survival is consistent with population projections derived from harvest numbers and earlier vital rates, as well as with an observed decline in the extent of sea ice habitat.

  16. Simulating polar bear energetics during a seasonal fast using a mechanistic model.

    Science.gov (United States)

    Mathewson, Paul D; Porter, Warren P

    2013-01-01

    In this study we tested the ability of a mechanistic model (Niche Mapper™) to accurately model adult, non-denning polar bear (Ursus maritimus) energetics while fasting during the ice-free season in the western Hudson Bay. The model uses a steady state heat balance approach, which calculates the metabolic rate that will allow an animal to maintain its core temperature in its particular microclimate conditions. Predicted weight loss for a 120 day fast typical of the 1990s was comparable to empirical studies of the population, and the model was able to reach a heat balance at the target metabolic rate for the entire fast, supporting use of the model to explore the impacts of climate change on polar bears. Niche Mapper predicted that all but the poorest condition bears would survive a 120 day fast under current climate conditions. When the fast extended to 180 days, Niche Mapper predicted mortality of up to 18% for males. Our results illustrate how environmental conditions, variation in animal properties, and thermoregulation processes may impact survival during extended fasts because polar bears were predicted to require additional energetic expenditure for thermoregulation during a 180 day fast. A uniform 3°C temperature increase reduced male mortality during a 180 day fast from 18% to 15%. Niche Mapper explicitly links an animal's energetics to environmental conditions and thus can be a valuable tool to help inform predictions of climate-related population changes. Since Niche Mapper is a generic model, it can make energetic predictions for other species threatened by climate change.

  17. Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination.

    Science.gov (United States)

    Pavlova, Viola; Nabe-Nielsen, Jacob; Dietz, Rune; Sonne, Christian; Grimm, Volker

    2016-11-30

    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. © 2016 The Author(s).

  18. Increasing nest predation will be insufficient to maintain polar bear body condition in the face of sea ice loss.

    Science.gov (United States)

    Dey, Cody J; Richardson, Evan; McGeachy, David; Iverson, Samuel A; Gilchrist, Hugh G; Semeniuk, Christina A D

    2017-05-01

    Climate change can influence interspecific interactions by differentially affecting species-specific phenology. In seasonal ice environments, there is evidence that polar bear predation of Arctic bird eggs is increasing because of earlier sea ice breakup, which forces polar bears into nearshore terrestrial environments where Arctic birds are nesting. Because polar bears can consume a large number of nests before becoming satiated, and because they can swim between island colonies, they could have dramatic influences on seabird and sea duck reproductive success. However, it is unclear whether nest foraging can provide an energetic benefit to polar bear populations, especially given the capacity of bird populations to redistribute in response to increasing predation pressure. In this study, we develop a spatially explicit agent-based model of the predator-prey relationship between polar bears and common eiders, a common and culturally important bird species for northern peoples. Our model is composed of two types of agents (polar bear agents and common eider hen agents) whose movements and decision heuristics are based on species-specific bioenergetic and behavioral ecological principles, and are influenced by historical and extrapolated sea ice conditions. Our model reproduces empirical findings that polar bear predation of bird nests is increasing and predicts an accelerating relationship between advancing ice breakup dates and the number of nests depredated. Despite increases in nest predation, our model predicts that polar bear body condition during the ice-free period will continue to decline. Finally, our model predicts that common eider nests will become more dispersed and will move closer to the mainland in response to increasing predation, possibly increasing their exposure to land-based predators and influencing the livelihood of local people that collect eider eggs and down. These results show that predator-prey interactions can have nonlinear responses to

  19. Three decades (1983-2010) of contaminant trends in East Greenland polar bears (Ursus maritimus). Part 1

    DEFF Research Database (Denmark)

    Dietz, Rune; Rigét, Frank F; Sonne, Christian

    2013-01-01

    Legacy organochlorine contaminants were determined in adipose tissues from 294 polar bears (Ursus maritimus) sampled in East Greenland in 23 of the 28years between 1983 and 2010. Of 19 major legacy contaminants and congeners (ΣPCB, 4 PCB congeners (CB153, 180, 170/190), ΣDDT, p,p'-DDE, p,p' -DDD...... bears (i.e. females...

  20. Polar bear use of a persistent food subsidy: insights from non-invasive genetic sampling in Alaska

    Science.gov (United States)

    Peacock, Elizabeth; Herreman, Jason

    2013-01-01

    Remains of bowhead whales (Balaena mysticetus) harvested by Iñupiat whalers are deposited in bone piles along the coast of Alaska and have become persistent and reliable food sources for polar bears (Ursus maritimus). The importance of bone piles to individuals and the population, the patterns of use, and the number, sex, and age of bears using these resources are poorly understood. We implemented barbed-wire hair snaring to obtain genetic identities from bears using the Point Barrow bone pile in winter 2010–11. Eighty-three percent of genotyped samples produced individual and sex identification. We identified 97 bears from 200 samples. Using genetic mark–recapture techniques, we estimated that 228 bears used the bone pile during November to February, which would represent approximately 15% of the Southern Beaufort Sea polar bear subpopulation, if all bears were from this subpopulation. We found that polar bears of all age and sex classes simultaneously used the bone pile. More males than females used the bone pile, and males predominated in February, likely because 1/3 of adult females would be denning during this period. On average, bears spent 10 days at the bone pile (median  =  5 days); the probability that an individual bear remained at the bone pile from week to week was 63% for females and 45% for males. Most bears in the sample were detected visiting the bone pile once or twice. We found some evidence of matrilineal fidelity to the bone pile, but the group of animals visiting the bone pile did not differ genetically from the Southern Beaufort Sea subpopulation, nor did patterns of relatedness. We demonstrate that bowhead whale bone piles may be an influential food subsidy for polar bears in the Barrow region in autumn and winter for all sex and age classes.

  1. Organochlorine contaminants in arctic marine food chains: identification, geographical distribution, and temporal trends in polar bears

    Energy Technology Data Exchange (ETDEWEB)

    Norstrom, R.J.; Simon, M.; Muir, D.C.G.; Schweinsburg, R.E.

    1988-09-01

    Contamination of Canadian arctic and subarctic marine ecosystems by organochlorine (OC) compounds was measured by analysis of polar bear (Ursus maritimus) tissues collected from 12 zones between 1982 and 1984. PCB congeners (S-PCB), chlordanes, DDT and metabolites, chlorobenzenes (S-CBz), hexachlorocyclohexane isomers (S-HC-H), and dieldrin were identified by high-resolution gas chromatography-mass spectrometry. Nonachlor-III, a nonachlor isomer in technical chlordane, was positively identified for the first time as an environmental contaminant. S-PCB and S-CHLOR accounted for >80% of the total organochlorines in adipose tissue. Six PCB congeners constituted approximately 93% of S-PCB in polar bears. Levels of most OCs were lowest in the high Arctic, intermediate in Baffin Bay, and highest in Hudson Bay. Levels of ..cap alpha..-HCH were evaluated in zones influenced by surface runoff. Levels of S-CHLOR were four times higher and levels of the other OCs were two times higher in adipose tissue of bears from Hudson Bay and Baffin Bay in 1984 than in adipose tissue archived since 1969 from these areas; levels of S-DDT did not change.

  2. Morphology of the lingual papillae of the polar bear (Ursus maritimus).

    Science.gov (United States)

    Emura, Shoichi; Sugiyama, Kazue; Kusuda, Satoshi

    2017-01-01

    We examined the dorsal lingual surfaces of a newborn and an old polar bears by using scanning electron microscopy. In the newborn polar bear, the filiform papilla on the lingual apex was cylindrical in shape. The connective tissue core of the filiform papillae was needle-shaped and that of the fungiform papillae was funnel-shaped. The filiform papillae on the lingual body was dome-shaped. The connective tissue core of the filiform papillae was U-shaped and that of the fungiform papillae was column-shaped. On the lingual apex and body, there could not distinguish the filiform from fungiform papillae. The connective tissue core of the filiform papilla was different from the fungiform papilla. The vallate papillae were surrounded by a groove and pad and the surface was smooth. In the old bear, the filiform papilla on the lingual apex had several pointed processes. The processes of the filiform papilla on the lingual body were larger than those of the lingual apex. The vallate papillae were surrounded by a groove and pad and the surface was rough. There are no foliate papillae.

  3. Arctic Forecasts Available from Polar Bear Exhibit as an Example of Formal/Informal Collaboration

    Science.gov (United States)

    Landis, C. E.; Cervenec, J.

    2012-12-01

    A subset of the general population enjoys and frequents informal education venues, offering an opportunity for lifelong learning that also enhances and supports formal education efforts. The Byrd Polar Research Center (BPRC) at The Ohio State University collaborated with the Columbus Zoo & Aquarium (CZA) in the development of their Polar Frontier exhibit, from its initial planning to the Grand Opening of the exhibit, through the present. Of course, the addition to the Zoo of polar bears and Arctic fox in the Polar Frontier has been very popular, with almost a 7% increase in visitors in 2010 when the exhibit opened. The CZA and BPRC are now investigating ways to increase the climate literacy impact of the exhibit, and to increase engagement with the topics through follow-on activities. For example, individuals or classes anywhere in the world can check forecasts from the Polar Weather and Research Forecasting model and compare them to observed conditions-- allowing deep investigation into changes in the Arctic. In addition, opportunities exist to adapt the Zoo School experience (affecting several Central Ohio school districts) and/or to enable regular participation through social media such as Facebook, Twitter, and other forms of digital communication. BPRC's sustained engagement with the CZA is an example of a trusted and meaningful partnership where open dialogue exists about providing the best learning experience for visitors. This presentation will share some of the lessons learned from this unique partnership, and strategies that are adopted to move it forward.

  4. Exposure to mixtures of organohalogen contaminants and associative interactions with thyroid hormones in East Greenland polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Villanger, Gro D.; Jenssen, Bjørn M.; Fjeldberg, Rita R.

    2011-01-01

    associations are not evidence per se of biological cause– effect relationships. Still, the results of the present study indicate that OHCs may affect circulating TH levels in East Greenland polar bears, adding to the “weight of evidence” suggesting that OHCs might interfere with thyroid homeostasis in polar...

  5. Temporal monitoring of liver and kidney lesions in contaminated East Greenland polar bears (Ursus maritimus) during 1999-2010.

    Science.gov (United States)

    Sonne, Christian; Letcher, Robert J; Leifsson, Pall S; Rigét, Frank F; Bechshøft, Thea Ø; Bossi, Rossana; Asmund, Gert; Dietz, Rune

    2012-11-01

    Organohalogen contaminants bioaccumulate to high concentrations in tissues of polar bears (Ursus maritimus). The exposure levels are in the order to be toxic to inner organs like liver and kidney. We therefore investigated the temporal development of lesions in liver (n=115) and kidney (n=122) samples from East Greenland polar bears taken over the 12 year period from 1999 to 2010. Seven liver and seven kidney lesions were observed of which six were age-related. Controlling for this, the analyses showed that hepatic steatosis and renal cell infiltrations, glomerular sclerosis and tubular hyperplasia decreased over the investigated time period (all ppolar bears. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. Assessment of the amount of polar bears ( Ursus maritimus) on the basis of perennial vessel counts

    Science.gov (United States)

    Matishov, G. G.; Chelintsev, N. G.; Goryaev, Yu. I.; Makarevich, P. R.; Ishkulov, D. G.

    2014-10-01

    This article presents a method of assessment of the amount of polar bears on the basis of data on vessel counts. The results of 32 vessel transect counts in the southern part of the Kara Sea are used as the primary data. They are processed in an original program using separate extrapolation by sectors and summarizing of data of several different counts. In recent years, the calculated amount of bears in the studied region has varied from 3300 to 3100 individuals (3200, on average). The relative statistical error of estimations smoothly decreases from 8 to 7%. The confidence interval of the estimation at statistical error of 7% and probability level of 95% is 2700-3500 individuals.

  7. Differences in mercury bioaccumulation between polar bears (Ursus maritimus) from the Canadian high- and sub-Arctic.

    Science.gov (United States)

    St Louis, Vincent L; Derocher, Andrew E; Stirling, Ian; Graydon, Jennifer A; Lee, Caroline; Jocksch, Erin; Richardson, Evan; Ghorpade, Sarah; Kwan, Alvin K; Kirk, Jane L; Lehnherr, Igor; Swanson, Heidi K

    2011-07-15

    Polar bears (Ursus maritimus) are being impacted by climate change and increased exposure to pollutants throughout their northern circumpolar range. In this study, we quantified concentrations of total mercury (THg) in the hair of polar bears from Canadian high- (southern Beaufort Sea, SBS) and sub- (western Hudson Bay, WHB) Arctic populations. Concentrations of THg in polar bears from the SBS population (14.8 ± 6.6 μg g(-1)) were significantly higher than in polar bears from WHB (4.1 ± 1.0 μg g(-1)). On the basis of δ(15)N signatures in hair, in conjunction with published δ(15)N signatures in particulate organic matter and sediments, we estimated that the pelagic and benthic food webs in the SBS are ∼ 4.7 and ∼ 4.0 trophic levels long, whereas in WHB they are only ∼ 3.6 and ∼ 3.3 trophic levels long. Furthermore, the more depleted δ(13)C ratios in hair from SBS polar bears relative to those from WHB suggests that SBS polar bears feed on food webs that are relatively more pelagic (and longer), whereas polar bears from WHB feed on those that are relatively more benthic (and shorter). Food web length and structure accounted for ∼ 67% of the variation we found in THg concentrations among all polar bears across both populations. The regional difference in polar bear hair THg concentrations was also likely due to regional differences in water-column concentrations of methyl Hg (the toxic form of Hg that biomagnifies through food webs) available for bioaccumulation at the base of the food webs. For example, concentrations of methylated Hg at mid-depths in the marine water column of the northern Canadian Arctic Archipelago were 79.8 ± 37.3 pg L(-1), whereas, in HB, they averaged only 38.3 ± 16.6 pg L(-1). We conclude that a longer food web and higher pelagic concentrations of methylated Hg available to initiate bioaccumulation in the BS resulted in higher concentrations of THg in polar bears from the SBS region compared to those inhabiting the western

  8. Enhanced biological processes associated with alopecia in polar bears (Ursus maritimus)

    Science.gov (United States)

    Bowen, Lizabeth; Miles, A. Keith; Stott, Jeffrey L.; Waters, Shannon C.; Atwood, Todd C.

    2015-01-01

    Populations of wildlife species worldwide experience incidents of mass morbidity and mortality. Primary or secondary drivers of these events may escape classical detection methods for identifying microbial insults, toxin exposure, or additional stressors. In 2012, 28% of polar bears sampled in a study in the southern Beaufort Sea region of Alaska had varying degrees of alopecia that was concomitant with reduced body condition. Concurrently, elevated numbers of sick or dead ringed seals were detected in the southern Beaufort, Chukchi, and Bering seas in 2012, resulting in the declaration of an unusual mortality event (UME) by the National Oceanic and Atmospheric Administration (NOAA). The primary and possible ancillary causative stressors of these events are unknown, and related physiological changes within individual animals have been undetectable using classical diagnostic methods. Here we present an emerging technology as a potentially guiding investigative approach aimed at elucidating the circumstances responsible for the susceptibility of certain polar bears to observed conditions. Using transcriptomic analysis we identified enhanced biological processes including immune response, viral defense, and response to stress in polar bears with alopecia. Our results support an alternative mechanism of investigation into the causative agents that, when used proactively, could serve as an early indicator for populations and species at risk. We suggest that current or classical methods for investigation into events of unusual morbidity and mortality can be costly, sometimes unfocused, and often inconclusive. Advances in technology allow for implementation of a holistic system of surveillance and investigation that could provide early warning of health concerns in wildlife species important to humans.

  9. Per- and polyfluoroalkyl substances (PFASs) - New endocrine disruptors in polar bears (Ursus maritimus)?

    Science.gov (United States)

    Pedersen, Kathrine Eggers; Letcher, Robert J; Sonne, Christian; Dietz, Rune; Styrishave, Bjarne

    2016-11-01

    Per- and polyfluoroalkyl substances (PFASs) are emerging in the Arctic and accumulate in brain tissues of East Greenland (EG) polar bears. In vitro studies have shown that PFASs might possess endocrine disrupting abilities and therefore the present study was conducted to investigate potential PFAS induced alterations in brain steroid concentrations. The concentrations of eleven steroid hormones were determined in eight brain regions from ten EG polar bears. Pregnenolone (PRE), the dominant progestagen, was found in mean concentrations of 5-47ng/g (ww) depending on brain region. PRE showed significantly (pbears. Dehydroepiandrosterone (DHEA) found in mean concentrations 0.67-4.58ng/g (ww) was the androgen found in highest concentrations. Among the estrogens estrone (E1) showed mean concentrations of 0.90-2.21ng/g (ww) and was the most abundant. Remaining steroid hormones were generally present in concentrations below 2ng/g (ww). Steroid levels in brain tissue could not be explained by steroid levels in plasma. There was however a trend towards increasing estrogen levels in plasma resulting in increasing levels of androgens in brain tissue. Correlative analyses showed positive associations between PFASs and 17α-hydroxypregnenolone (OH-PRE) (e.g. perflouroalkyl sulfonates (∑PFSA): pbears. It is, however, not possible to determine whether alterations in brain steroid concentrations arise from interference with de novo steroid synthesis or via disruption of peripheral steroidogenic tissues mainly in gonads and feedback mechanisms. Steroids are important for brain plasticity and gender specific behavior as well as postnatal development and sexually dimorph brain function. The present work indicates an urgent need for a better mechanistic understanding of how PFASs may affect the endocrine system of polar bears and potentially other mammal species. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Enhanced biological processes associated with alopecia in polar bears (Ursus maritimus).

    Science.gov (United States)

    Bowen, Lizabeth; Miles, A Keith; Stott, Jeffrey; Waters, Shannon; Atwood, Todd

    2015-10-01

    Populations of wildlife species worldwide experience incidents of mass morbidity and mortality. Primary or secondary drivers of these events may escape classical detection methods for identifying microbial insults, toxin exposure, or additional stressors. In 2012, 28% of polar bears sampled in a study in the southern Beaufort Sea region of Alaska had varying degrees of alopecia that was concomitant with reduced body condition. Concurrently, elevated numbers of sick or dead ringed seals were detected in the southern Beaufort, Chukchi, and Bering seas in 2012, resulting in the declaration of an unusual mortality event (UME) by the National Oceanic and Atmospheric Administration (NOAA). The primary and possible ancillary causative stressors of these events are unknown, and related physiological changes within individual animals have been undetectable using classical diagnostic methods. Here we present an emerging technology as a potentially guiding investigative approach aimed at elucidating the circumstances responsible for the susceptibility of certain polar bears to observed conditions. Using transcriptomic analysis we identified enhanced biological processes including immune response, viral defense, and response to stress in polar bears with alopecia. Our results support an alternative mechanism of investigation into the causative agents that, when used proactively, could serve as an early indicator for populations and species at risk. We suggest that current or classical methods for investigation into events of unusual morbidity and mortality can be costly, sometimes unfocused, and often inconclusive. Advances in technology allow for implementation of a holistic system of surveillance and investigation that could provide early warning of health concerns in wildlife species important to humans. Published by Elsevier B.V.

  11. Modeling Population-Level Consequences of Polychlorinated Biphenyl Exposure in East Greenland Polar Bears.

    Science.gov (United States)

    Pavlova, Viola; Grimm, Volker; Dietz, Rune; Sonne, Christian; Vorkamp, Katrin; Rigét, Frank F; Letcher, Robert J; Gustavson, Kim; Desforges, Jean-Pierre; Nabe-Nielsen, Jacob

    2016-01-01

    Polychlorinated biphenyls (PCBs) can cause endocrine disruption, cancer, immunosuppression, or reproductive failure in animals. We used an individual-based model to explore whether and how PCB-associated reproductive failure could affect the dynamics of a hypothetical polar bear (Ursus maritimus) population exposed to PCBs to the same degree as the East Greenland subpopulation. Dose-response data from experimental studies on a surrogate species, the mink (Mustela vision), were used in the absence of similar data for polar bears. Two alternative types of reproductive failure in relation to maternal sum-PCB concentrations were considered: increased abortion rate and increased cub mortality. We found that the quantitative impact of PCB-induced reproductive failure on population growth rate depended largely on the actual type of reproductive failure involved. Critical potencies of the dose-response relationship for decreasing the population growth rate were established for both modeled types of reproductive failure. Comparing the model predictions of the age-dependent trend of sum-PCBs concentrations in females with actual field measurements from East Greenland indicated that it was unlikely that PCB exposure caused a high incidence of abortions in the subpopulation. However, on the basis of this analysis, it could not be excluded that PCB exposure contributes to higher cub mortality. Our results highlight the necessity for further research on the possible influence of PCBs on polar bear reproduction regarding their physiological pathway. This includes determining the exact cause of reproductive failure, i.e., in utero exposure versus lactational exposure of offspring; the timing of offspring death; and establishing the most relevant reference metrics for the dose-response relationship.

  12. What to eat now? Shifts in polar bear diet during the ice-free season in western Hudson Bay

    Science.gov (United States)

    Gormezano, Linda J; Rockwell, Robert F

    2013-01-01

    Under current climate trends, spring ice breakup in Hudson Bay is advancing rapidly, leaving polar bears (Ursus maritimus) less time to hunt seals during the spring when they accumulate the majority of their annual fat reserves. For this reason, foods that polar bears consume during the ice-free season may become increasingly important in alleviating nutritional stress from lost seal hunting opportunities. Defining how the terrestrial diet might have changed since the onset of rapid climate change is an important step in understanding how polar bears may be reacting to climate change. We characterized the current terrestrial diet of polar bears in western Hudson Bay by evaluating the contents of passively sampled scat and comparing it to a similar study conducted 40 years ago. While the two terrestrial diets broadly overlap, polar bears currently appear to be exploiting increasingly abundant resources such as caribou (Rangifer tarandus) and snow geese (Chen caerulescens caerulescens) and newly available resources such as eggs. This opportunistic shift is similar to the diet mixing strategy common among other Arctic predators and bear species. We discuss whether the observed diet shift is solely a response to a nutritional stress or is an expression of plastic foraging behavior. PMID:24223286

  13. Textile solar light collectors based on models for polar bear hair

    Energy Technology Data Exchange (ETDEWEB)

    Bahners, Thomas; Schlosser, Uwe; Schollmeyer, Eckhard [Deutsches Textilforschungszentrum Nord-West e.V., Adlerstr. 1, D-47798 Krefeld (Germany); Gutmann, Rainer [Institut fuer Textilchemie und Chemiefasern, Koerschtalstr. 26, D-73770 Denkendorf (Germany)

    2008-12-15

    Concepts of technical fibers following models for the polar bear hair to be used for textile solar collectors are discussed. The approach to coat fibers with a thin layer into which fluorescent dyestuff was dispersed was studied experimentally. Modified fibers made of different polymers were characterized with respect to optical properties relevant for the bionic model. In the case of poly(methylmethacrylate) fibers, the envisaged effect could be achieved to high efficiency. The optical performance could be enhanced by ultrasonic dispersion of the dyestuff in the coating matrix. The effect is less significant in semi-crystalline fibers such as poly(ethylene terephthalate), which is attributed to diffuse scattering. (author)

  14. Sulfonation of environmental chemicals and their metabolites in the polar bear (Ursus maritimus).

    Science.gov (United States)

    Sacco, James C; James, Margaret O

    2005-09-01

    Although its habitat comprises mostly remote regions of the Arctic, the polar bear is subject to bioaccumulation of persistent environmental pollutants. Along with their phase I metabolites, they are potential substrates for detoxification via sulfonation and glucuronidation. The capability of polar bear liver to sulfonate a structurally diverse group of environmental chemicals, that is, 3-hydroxybenzo[a]pyrene (3-OH-B[a]P), triclosan, 4'-hydroxy-3,3',4,5'-tetrachlorobiphenyl (4'OH-PCB79), 4'-hydroxy-2,3,3',4,5,5'-hexachlorobiphenyl (4'-OH-PCB159), 4'-hydroxy-2,3,3',5,5',6-hexachlorobiphenyl (4'-OH-PCB165), the methoxychlor metabolite 2-(4-methoxyphenyl)-2-(4-hydroxyphenyl)-1,1,1-trichloroethane (OHMXC), tris(4-chlorophenyl)-methanol (TCPM), and pentachlorophenol (PCP) was investigated. The glucuronidation of 3-OH-B[a]P was also studied. Enzyme activity was assayed by incubation of liver cytosol or microsomes derived from three adult male polar bears with 3'-phosphoadenosine-5'-phosphosulfate or uridine 5'-diphosphoglucuronic acid and substrate, followed by fluorometric or radiochemical thin-layer chromatographic analysis. The efficiency of sulfonation decreased in the order 3-OH-B[a]P > triclosan > 4'-OH-PCB79 > OHMXC > 4'-OH-PCB165 > TCPM > 4'-OH-PCB159 > PCP, all of which produced detectable sulfate conjugates. The 3-OH-B[a]P substrate was readily sulfonated and glucuronidated (apparent K(m) 0.41, 1.4 microM, and apparent V(max) 0.50, 3.00 nmol/min/mg, respectively). UDP-glucuronic acid kinetics suggested the presence of multiple enzymes glucuronidating 3-OH-B[a]P. Substrate inhibition was observed for the sulfonation of 3-OH-B[a]P and 4'OH-PCB79 (K(i) 1.0 and 217 microM, respectively). Triclosan was the most rapidly sulfated (apparent V(max) 1008 pmol/min/mg) of the substrates tested. Since sulfonation of an acyclic tertiary alcoholic group, as in TCPM, has not previously been reported, we also examined TCPM conjugation in humans and catfish, both of which

  15. Using satellite telemetry to define spatial population structure in polar bears in the Norwegian and western Russian Arctic

    Science.gov (United States)

    Mauritzen, Mette; Derocher, Andrew E.; Wiig, Øystein; Belikov, Stanislav; Boltunov, Andrei N.; Garner, Gerald W.

    2002-01-01

    1. Animal populations, defined by geographical areas within a species’ distribution where population dynamics are largely regulated by births and deaths rather than by migration from surrounding areas, may be the correct unit for wildlife management. However, in heterogeneous landscapes varying habitat quality may yield subpopulations with distinct patterns in resource use and demography significant to the dynamics of populations.2. To define the spatial population structure of polar bears Ursus maritimus in the Norwegian and western Russian Arctic, and to assess the existence of a shared population between the two countries, we analysed satellite telemetry data obtained from 105 female polar bears over 12 years.3. Using both cluster analyses and home-range estimation methods, we identified five population units inhabiting areas with different sea-ice characteristics and prey availability.4. The continuous distribution of polar bear positions indicated that the different subpopulations formed one continuous polar bear population in the Norwegian and western Russian Arctic. Hence, Norway and Russia have a shared management responsibility.5. The spatial population structure identified will provide a guide for evaluating geographical patterns in polar bear ecology, the dynamics of polar bear–seal relationships and the effects of habitat alteration due to climate change. The work illustrates the importance of defining population borders and subpopulation structure in understanding the dynamics and management of larger animals.

  16. Flame retardants and methoxylated and hydroxylated polybrominated diphenyl ethers in two Norwegian Arctic top predators: glaucous gulls and polar bears.

    Science.gov (United States)

    Verreault, Jonathan; Gabrielsen, Geir W; Chu, Shaogang; Muir, Derek C G; Andersen, Magnus; Hamaed, Ahmad; Letcher, Robert J

    2005-08-15

    The brominated flame retardants have been subject of a particular environmental focus in the Arctic. The present study investigated the congener patterns and levels of total hexabromocyclododecane (HBCD), polybrominated biphenyls, polybrominated diphenyl ethers (PBDEs), as well as methoxylated (MeO) and hydroxylated (OH) PBDEs in plasma samples of glaucous gulls (Larus hyperboreus) and polar bears (Ursus maritimus) from the Norwegian Arctic. The analyses revealed the presence of total HBCD (0.07-1.24 ng/g wet wt) and brominated biphenyl 101 (polar bears. Sum (sigma) concentrations of the 12 PBDEs monitored in glaucous gulls (range: 8.23-67.5 ng/g wet wt) surpassed largely those of polar bears (range: 2.65-9.72 ng/g wet wt). Two higher brominated PBDEs, BDE183 and BDE209, were detected, and thus bioaccumulated to a limited degree, in glaucous gulls with concentrations ranging from polar bear plasma, BDE183 was polar bears (sigmaMeO-PBDE up to 0.17 ng/g wet wt), followed by 4'-MeO-BDE49 and 6-MeO-BDE47. The 3-OH-BDE47, 4'-OH-BDE49, and 6-OH-BDE47 congeners were also detected in glaucous gulls (sigmaOH-PBDE up to 1.05 ng/g wet wt), although in polar bears 4'-OH-BDE49 was the only congener quantifiable in 13% of the samples. The presence of MeO- and OH-PBDEs in plasma of both species suggests possible dietary uptake from naturally occurring sources (e.g., marine sponges and green algae), but also metabolically derived biotransformation of PBDEs such as BDE47 could be a contributing factor. Our findings suggest that there are dissimilar biochemical mechanisms involved in PCB and PBDE metabolism and accumulation/elimination and/or OH-PBDE accumulation and retention in glaucous gulls and polar bears.

  17. Effects of earlier sea ice breakup on survival and population size of polar bears in western Hudson Bay

    Science.gov (United States)

    Regehr, E.V.; Lunn, N.J.; Amstrup, Steven C.; Stirling, I.

    2007-01-01

    Some of the most pronounced ecological responses to climatic warming are expected to occur in polar marine regions, where temperature increases have been the greatest and sea ice provides a sensitive mechanism by which climatic conditions affect sympagic (i.e., with ice) species. Population-level effects of climatic change, however, remain difficult to quantify. We used a flexible extension of Cormack-Jolly-Seber capture-recapture models to estimate population size and survival for polar bears (Ursus maritimus), one of the most ice-dependent of Arctic marine mammals. We analyzed data for polar bears captured from 1984 to 2004 along the western coast of Hudson Bay and in the community of Churchill, Manitoba, Canada. The Western Hudson Bay polar bear population declined from 1,194 (95% CI = 1,020-1,368) in 1987 to 935 (95% CI = 794-1,076) in 2004. Total apparent survival of prime-adult polar bears (5-19 yr) was stable for females (0.93; 95% CI = 0.91-0.94) and males (0.90; 95% CI = 0.88-0.91). Survival of juvenile, subadult, and senescent-adult polar bears was correlated with spring sea ice breakup date, which was variable among years and occurred approximately 3 weeks earlier in 2004 than in 1984. We propose that this correlation provides evidence for a causal association between earlier sea ice breakup (due to climatic warming) and decreased polar bear survival. It may also explain why Churchill, like other communities along the western coast of Hudson Bay, has experienced an increase in human-polar bear interactions in recent years. Earlier sea ice breakup may have resulted in a larger number of nutritionally stressed polar bears, which are encroaching on human habitations in search of supplemental food. Because western Hudson Bay is near the southern limit of the species' range, our findings may foreshadow the demographic responses and management challenges that more northerly polar bear populations will experience if climatic warming in the Arctic continues as

  18. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic.

    Science.gov (United States)

    Peacock, Elizabeth; Sonsthagen, Sarah A; Obbard, Martyn E; Boltunov, Andrei; Regehr, Eric V; Ovsyanikov, Nikita; Aars, Jon; Atkinson, Stephen N; Sage, George K; Hope, Andrew G; Zeyl, Eve; Bachmann, Lutz; Ehrich, Dorothee; Scribner, Kim T; Amstrup, Steven C; Belikov, Stanislav; Born, Erik W; Derocher, Andrew E; Stirling, Ian; Taylor, Mitchell K; Wiig, Øystein; Paetkau, David; Talbot, Sandra L

    2015-01-01

    We provide an expansive analysis of polar bear (Ursus maritimus) circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1-3 generations) directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (U. arctos) uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation connectivity will allow

  19. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic

    Science.gov (United States)

    Peacock, Elizabeth; Sonsthagen, Sarah A.; Obbard, Martyn E.; Boltunov, Andrei N.; Regehr, Eric V.; Ovsyanikov, Nikita; Aars, Jon; Atkinson, Stephen N.; Sage, George K.; Hope, Andrew G.; Zeyl, Eve; Bachmann, Lutz; Ehrich, Dorothee; Scribner, Kim T.; Amstrup, Steven C.; Belikov, Stanislav; Born, Erik W.; Derocher, Andrew E.; Stirling, Ian; Taylor, Mitchell K.; Wiig, Øystein; Paetkau, David; Talbot, Sandra L.

    2015-01-01

    We provide an expansive analysis of polar bear (Ursus maritimus) circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1–3 generations) directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (U. arctos) uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation connectivity will

  20. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic.

    Directory of Open Access Journals (Sweden)

    Elizabeth Peacock

    Full Text Available We provide an expansive analysis of polar bear (Ursus maritimus circumpolar genetic variation during the last two decades of decline in their sea-ice habitat. We sought to evaluate whether their genetic diversity and structure have changed over this period of habitat decline, how their current genetic patterns compare with past patterns, and how genetic demography changed with ancient fluctuations in climate. Characterizing their circumpolar genetic structure using microsatellite data, we defined four clusters that largely correspond to current ecological and oceanographic factors: Eastern Polar Basin, Western Polar Basin, Canadian Archipelago and Southern Canada. We document evidence for recent (ca. last 1-3 generations directional gene flow from Southern Canada and the Eastern Polar Basin towards the Canadian Archipelago, an area hypothesized to be a future refugium for polar bears as climate-induced habitat decline continues. Our data provide empirical evidence in support of this hypothesis. The direction of current gene flow differs from earlier patterns of gene flow in the Holocene. From analyses of mitochondrial DNA, the Canadian Archipelago cluster and the Barents Sea subpopulation within the Eastern Polar Basin cluster did not show signals of population expansion, suggesting these areas may have served also as past interglacial refugia. Mismatch analyses of mitochondrial DNA data from polar and the paraphyletic brown bear (U. arctos uncovered offset signals in timing of population expansion between the two species, that are attributed to differential demographic responses to past climate cycling. Mitogenomic structure of polar bears was shallow and developed recently, in contrast to the multiple clades of brown bears. We found no genetic signatures of recent hybridization between the species in our large, circumpolar sample, suggesting that recently observed hybrids represent localized events. Documenting changes in subpopulation

  1. Tasmanian tigers and polar bears: The documentary moving image and (species loss

    Directory of Open Access Journals (Sweden)

    Belinda Smaill

    2015-04-01

    Full Text Available In this essay I explore how two divergent examples of the nonfiction moving image can be understood in relation to the problem of representing species loss. The species that provide the platform for this consideration are the thylacine, better known as the Tasmanian tiger, and the polar bear. They represent the two contingencies of species loss: endangerment and extinction. My analysis is structured around moving images from the 1930s of the last known thylacine and the very different example of Arctic Tale (Adam Ravetch, Sarah Robertson, 2007, a ‘Disneyfied’ film that dramatises climate change and its impact on the polar bear. Species loss is frequently perceived in a humanist sense, reflecting how we ‘imagine ourselves’ or anthropocentric charactersations of non-human others. I offer a close analysis of the two films, examining the problem of representing extinction through a consideration of the play of absence and presence, vitality and extinguishment, that characterises both the ontology of cinema and narratives about species loss.

  2. Ecological change drives a decline in mercury concentrations in southern Beaufort Sea polar bears

    Science.gov (United States)

    McKinney, Melissa A.; Atwood, Todd C.; Pedro, Sara; Peacock, Elizabeth

    2017-01-01

    We evaluated total mercury (THg) concentrations and trends in polar bears from the southern Beaufort Sea subpopulation from 2004 to 2011. Hair THg concentrations ranged widely among individuals from 0.6 to 13.3 μg g–1 dry weight (mean: 3.5 ± 0.2 μg g–1). Concentrations differed among sex and age classes: solitary adult females ≈ adult females with cubs ≈ subadults > adult males ≈ yearlings > cubs-of-the-year ≈ 2 year old dependent cubs. No variation was observed between spring and fall samples. For spring-sampled adults, THg concentrations declined by 13% per year, contrasting recent trends observed for other Western Hemispheric Arctic biota. Concentrations also declined by 15% per year considering adult males only, while a slower, nonsignificant decrease of 4.4% per year was found for adult females. Lower THg concentrations were associated with higher body mass index (BMI) and higher proportions of lower trophic position food resources consumed. Because BMI and diet were related, and the relationship to THg was strongest for BMI, trends were re-evaluated adjusting for BMI as the covariate. The adjusted annual decline was not significant. These findings indicate that changes in foraging ecology, not declining environmental concentrations of mercury, are driving short-term declines in THg concentrations in southern Beaufort Sea polar bears.

  3. Organohalogen concentrations in blood and adipose tissue of Southern Beaufort Sea polar bears

    Science.gov (United States)

    Bentzen, T.W.; Muir, D.C.G.; Amstrup, Steven C.; O'Hara, T. M.

    2008-01-01

    We analyzed 151 organohalogen chemicals (OHCs) in whole blood and subcutaneous fat of 57 polar bears sampled along the Alaskan Beaufort Sea coast in spring, 2003. All major organochlorine pesticides, PCBs, PBDEs and their congeners were assessed. Concentrations of most OHCs continue to be lower among Southern Beaufort Sea polar bears than reported for other populations. Additionally, toxaphenes and related compounds were assessed in adipose tissue, and 8 perflourinated compounds (PFCs) were examined in blood. Perfluorooctane sulfonate (PFOS) concentrations exceeded those of any other contaminant measured in blood. ??Chlordane concentrations were higher in females, and both ??PCBs and ??Chlordane concentrations in adipose tissue decreased significantly with age. The rank order of OHC mean concentrations; ??PCB > ??10PCB > PCB153 > ??Chlordane > Oxychlordane > PCB180 > ??HCH > ??-HCH > ??DDT > p,p-DDE > ??PBDE > HCB > Toxaphene was similar for compounds above detection limits in both fat and blood. Although correlation between OHC concentrations in blood and adipose tissue was examined, the predictability of concentrations in one matrix for the other was limited. ?? 2008 Elsevier B.V.

  4. Ecological Change Drives a Decline in Mercury Concentrations in Southern Beaufort Sea Polar Bears.

    Science.gov (United States)

    McKinney, Melissa A; Atwood, Todd C; Pedro, Sara; Peacock, Elizabeth

    2017-07-18

    We evaluated total mercury (THg) concentrations and trends in polar bears from the southern Beaufort Sea subpopulation from 2004 to 2011. Hair THg concentrations ranged widely among individuals from 0.6 to 13.3 μg g -1 dry weight (mean: 3.5 ± 0.2 μg g -1 ). Concentrations differed among sex and age classes: solitary adult females ≈ adult females with cubs ≈ subadults > adult males ≈ yearlings > cubs-of-the-year ≈ 2 year old dependent cubs. No variation was observed between spring and fall samples. For spring-sampled adults, THg concentrations declined by 13% per year, contrasting recent trends observed for other Western Hemispheric Arctic biota. Concentrations also declined by 15% per year considering adult males only, while a slower, nonsignificant decrease of 4.4% per year was found for adult females. Lower THg concentrations were associated with higher body mass index (BMI) and higher proportions of lower trophic position food resources consumed. Because BMI and diet were related, and the relationship to THg was strongest for BMI, trends were re-evaluated adjusting for BMI as the covariate. The adjusted annual decline was not significant. These findings indicate that changes in foraging ecology, not declining environmental concentrations of mercury, are driving short-term declines in THg concentrations in southern Beaufort Sea polar bears.

  5. Tissue-specific concentrations and patterns of perfluoroalkyl carboxylates and sulfonates in East Greenland polar bears.

    Science.gov (United States)

    Greaves, Alana K; Letcher, Robert J; Sonne, Christian; Dietz, Rune; Born, Erik W

    2012-11-06

    Several perfluoroalkyl carboxylates (PFCAs) and perfluoroalkyl sulfonates (PFSAs) of varying chain length are bioaccumulative in biota. However, wildlife reports have focused on liver and with very little examination of other tissues, and thus there is a limited understanding of their distribution and potential effects in the mammalian body. In the present study, the comparative accumulation of C(6) to C(15) PFCAs, C(4), C(6), C(8) and C(10) PFSAs, and select precursors were examined in the liver, blood, muscle, adipose, and brain of 20 polar bears (Ursus maritimus) from Scoresby Sound, Central East Greenland. Overall, PFSA and PFCA concentrations were highest in liver followed by blood > brain > muscle ≈ adipose. Liver and blood samples contained proportionally more of the shorter/medium chain length (C(6) to C(11)) PFCAs, whereas adipose and brain samples were dominated by longer chain (C(13) to C(15)) PFCAs. PFCAs with lower lipophilicities accumulated more in the liver, whereas the brain accumulated PFCAs with higher lipophilicities. The concentration ratios (±SE) between perfluorooctane sulfonate and its precursor perfluorooctane sulfonamide varied among tissues from 9 (±1):1 (muscle) to 36 (±7):1 (liver). PFCA and PFSA patterns in polar bears indicate that the pharmacokinetics of these compounds are to some extent tissue-specific, and are the result of several factors that may include differing protein interactions throughout the body.

  6. Associations between complex OHC mixtures and thyroid and cortisol hormone levels in East Greenland polar bears.

    Science.gov (United States)

    Bechshøft, T Ø; Sonne, C; Dietz, R; Born, E W; Muir, D C G; Letcher, R J; Novak, M A; Henchey, E; Meyer, J S; Jenssen, B M; Villanger, G D

    2012-07-01

    The multivariate relationship between hair cortisol, whole blood thyroid hormones, and the complex mixtures of organohalogen contaminant (OHC) levels measured in subcutaneous adipose of 23 East Greenland polar bears (eight males and 15 females, all sampled between the years 1999 and 2001) was analyzed using projection to latent structure (PLS) regression modeling. In the resulting PLS model, most important variables with a negative influence on cortisol levels were particularly BDE-99, but also CB-180, -201, BDE-153, and CB-170/190. The most important variables with a positive influence on cortisol were CB-66/95, α-HCH, TT3, as well as heptachlor epoxide, dieldrin, BDE-47, p,p'-DDD. Although statistical modeling does not necessarily fully explain biological cause-effect relationships, relationships indicate that (1) the hypothalamic-pituitary-adrenal (HPA) axis in East Greenland polar bears is likely to be affected by OHC-contaminants and (2) the association between OHCs and cortisol may be linked with the hypothalamus-pituitary-thyroid (HPT) axis. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. A novel method for analysing key corticosteroids in polar bear (Ursus maritimus) hair using liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Weisser, Johan J; Hansen, Martin; Björklund, Erland; Sonne, Christian; Dietz, Rune; Styrishave, Bjarne

    2016-04-01

    This paper presents the development and evaluation of a methodology for extraction, clean-up and analysis of three key corticosteroids (aldosterone, cortisol and corticosterone) in polar bear hair. Such a methodology can be used to monitor stress biomarkers in polar bears and may provide as a useful tool for long-term and retrospective information. We developed a combined pressurized liquid extraction (PLE)-solid phase extraction (SPE) procedure for corticosteroid extraction and clean-up followed by high pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis. This procedure allows for the simultaneous determination of multiple steroids, which is in contrast to previous polar bear studies based on ELISA techniques. Absolute method recoveries were 81%, 75% and 60% for cortisol, corticosterone and aldosterone, respectively. We applied the developed method on a hair sample pooled from four East Greenland polar bears. Herein cortisol and corticosterone were successfully determined in levels of 0.32±0.02ng/g hair and 0.13±0.02ng/g hair, respectively. Aldosterone was below limit of detection (LOD<0.17ng/g). The cortisol hair concentration found in these East Greenland polar bears was consistent with cortisol levels previously determined in the Southern Hudson Bay and James Bay in Canada using ELISA kits. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Environmental contaminants activate human and polar bear (Ursus maritimus) pregnane X receptors (PXR, NR1I2) differently.

    Science.gov (United States)

    Lille-Langøy, Roger; Goldstone, Jared V; Rusten, Marte; Milnes, Matthew R; Male, Rune; Stegeman, John J; Blumberg, Bruce; Goksøyr, Anders

    2015-04-01

    Many persistent organic pollutants (POPs) accumulate readily in polar bears because of their position as apex predators in Arctic food webs. The pregnane X receptor (PXR, formally NR1I2, here proposed to be named promiscuous xenobiotic receptor) is a xenobiotic sensor that is directly involved in metabolizing pathways of a wide range of environmental contaminants. In the present study, we comparably assess the ability of 51 selected pharmaceuticals, pesticides and emerging contaminants to activate PXRs from polar bears and humans using an in vitro luciferase reporter gene assay. We found that polar bear PXR is activated by a wide range of our test compounds (68%) but has a slightly more narrow ligand specificity than human PXR that was activated by 86% of the 51 test compounds. The majority of the agonists identified (70%) produces a stronger induction of the reporter gene via human PXR than via polar bear PXR, however with some notable and environmentally relevant exceptions. Due to the observed differences in activation of polar bear and human PXRs, exposure of each species to environmental agents is likely to induce biotransformation differently in the two species. Bioinformatics analyses and structural modeling studies suggest that amino acids that are not part of the ligand-binding domain and do not interact with the ligand can modulate receptor activation. Copyright © 2015. Published by Elsevier Inc.

  9. Polar Bear Optimization Algorithm: Meta-Heuristic with Fast Population Movement and Dynamic Birth and Death Mechanism

    Directory of Open Access Journals (Sweden)

    Dawid Połap

    2017-09-01

    Full Text Available In the proposed article, we present a nature-inspired optimization algorithm, which we called Polar Bear Optimization Algorithm (PBO. The inspiration to develop the algorithm comes from the way polar bears hunt to survive in harsh arctic conditions. These carnivorous mammals are active all year round. Frosty climate, unfavorable to other animals, has made polar bears adapt to the specific mode of exploration and hunting in large areas, not only over ice but also water. The proposed novel mathematical model of the way polar bears move in the search for food and hunt can be a valuable method of optimization for various theoretical and practical problems. Optimization is very similar to nature, similarly to search for optimal solutions for mathematical models animals search for optimal conditions to develop in their natural environments. In this method. we have used a model of polar bear behaviors as a search engine for optimal solutions. Proposed simulated adaptation to harsh winter conditions is an advantage for local and global search, while birth and death mechanism controls the population. Proposed PBO was evaluated and compared to other meta-heuristic algorithms using sample test functions and some classical engineering problems. Experimental research results were compared to other algorithms and analyzed using various parameters. The analysis allowed us to identify the leading advantages which are rapid recognition of the area by the relevant population and efficient birth and death mechanism to improve global and local search within the solution space.

  10. Catalogue of polar bear (Ursus maritimus) maternal den locations in the Beaufort Sea and neighboring regions, Alaska, 1910-2010

    Science.gov (United States)

    Durner, George M.; Fischbach, Anthony S.; Amstrup, Steven C.; Douglas, David C.

    2010-01-01

    This report presents data on the approximate locations and methods of discovery of 392 polar bear (Ursus maritimus) maternal dens found in the Beaufort Sea and neighboring regions between 1910 and 2010 that are archived by the U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska. A description of data collection methods, biases associated with collection method, primary time periods, and spatial resolution are provided. Polar bears in the Beaufort Sea and nearby regions den on both the sea ice and on land. Standardized VHF surveys and satellite radio telemetry data provide a general understanding of where polar bears have denned in this region over the past 3 decades. Den observations made during other research activities and anecdotal reports from other government agencies, coastal residents, and industry personnel also are reported. Data on past polar bear maternal den locations are provided to inform the public and to provide information for natural resource agencies in planning activities to avoid or minimize interference with polar bear maternity dens.

  11. Mercury concentrations in Southern Beaufort Sea polar bears: variation based on stable isotopes of carbon and nitrogen.

    Science.gov (United States)

    Cardona-Marek, Tamara; Knott, Katrina K; Meyer, Benjamin E; O'Hara, Todd M

    2009-07-01

    Total Hg concentration was measured in hair and whole blood of 52 adult Southern Beaufort Sea polar bears (Ursus maritimus) captured in the spring of 2005. Stable isotopic signatures (i.e., 13C/12C, delta13C; 15N/14N, delta15N) in hair and two blood compartments (packed blood cells/clot and serum) were determined to assess the variation of Hg concentrations among polar bears in relation to their feeding ecology and other biological factors. Concentrations of Hg in hair and blood (2.2-23.9 microg/g dry wt and 0.007-0.213 microg/g wet wt, respectively) were within the range of values previously reported for polar bears in Canada and East Greenland. Mercury concentration in hair from females was higher than that in hair from males, and concentration was related to interactions between delta13C, delta15N, and longitude of capture location. Mercury concentrations in hair were inversely correlated to delta13C in hair and blood, suggesting that polar bears with greater total Hg concentrations fed more on pelagic prey, such as ringed seals or beluga whale, than on benthic prey. Variability in Hg concentrations in polar bear hair and blood may be the result of intraspecific or regional variation in prey selection rather than strictly trophic level interactions.

  12. Skull pathology in East Greenland and Svalbard polar bears (Ursus maritimus) during 1892 to 2002 in relation to organochlorine pollution

    International Nuclear Information System (INIS)

    Sonne, Christian; Riget, Frank F.; Dietz, Rune; Wiig, Oystein; Kirkegaard, Maja; Born, Erik W.

    2007-01-01

    East Greenland and Svalbard polar bears (Ursus maritimus) are heavily polluted with long-range transported organochlorines such as PCBs (polychlorinated biphenyls). To investigate the negative health impacts, a time-trend study of skull pathology was conducted on 269 East Greenland and 241 Svalbard polar bears. The skulls were sampled during 1892-2002 and 1964-1992, respectively. Seven different pathological changes were found: adonti, displacement of teeth, caries, osseous proliferations, exostosis, tooth wear and periodontitis. Only tooth wear and periodontitis was in a prevalence that allowed statistical treatment. The most severe cases of tooth wear and periodontitis were accompanied by a substantial loss of alveolar bone structure. The prevalence of tooth wear and periodontitis increased significantly with age (p < 0.001) with incisor wear being more severe than in canines, premolars and molars (p < 0.001). No sex difference was found for tooth wear (p = 0.22) while a significant difference between sexes was found for periodontitis (p = 0.01) with males having higher prevalence than females (odds ratio of 2.5 for males:females). In East Greenland, the prevalence of tooth wear was significantly higher in polar bears collected in the pre pollution period (< 1960) than in bears sampled during polluted periods (1960-1980 and 1981-2002) (p < 0.001). Regarding periodontitis, the prevalence was not significantly different between pre-pollution and pollution periods (p = 0.309). Polar bears from Svalbard had significantly higher prevalence of tooth wear (p < 0.001) and periodontitis (p = 0.02) than polar bears from East Greenland. The tooth wear and periodontitis odds ratios for Svalbard:East Greenland were 135 and 2.6, respectively. Hence, we found a clear age/sex link and geographical difference but no evidence for an association between skull pathology and exposure to organochlorines in East Greenland and Svalbard polar bears

  13. Skull pathology in East Greenland and Svalbard polar bears (Ursus maritimus) during 1892 to 2002 in relation to organochlorine pollution

    Energy Technology Data Exchange (ETDEWEB)

    Sonne, Christian [National Environmental Research Institute, Department of Arctic Environment, Frederiksborgvej 399, DK-4000 Roskilde (Denmark) and Department of Veterinary Basic Sciences, Royal Veterinary and Agricultural University, Buelowsvej 17, DK-1870 Frederiksberg C (Denmark)]. E-mail: csh@dmu.dk; Riget, Frank F. [National Environmental Research Institute, Department of Arctic Environment, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Dietz, Rune [National Environmental Research Institute, Department of Arctic Environment, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Wiig, Oystein [Natural History Museum, University of Oslo, PO Box 1172 Blindern, N-0562 Oslo (Norway); Kirkegaard, Maja [National Environmental Research Institute, Department of Arctic Environment, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Born, Erik W. [Greenland Institute of Natural Resources, PO Box 570, DK-3900 Nuuk, Greenland (Denmark)

    2007-01-01

    East Greenland and Svalbard polar bears (Ursus maritimus) are heavily polluted with long-range transported organochlorines such as PCBs (polychlorinated biphenyls). To investigate the negative health impacts, a time-trend study of skull pathology was conducted on 269 East Greenland and 241 Svalbard polar bears. The skulls were sampled during 1892-2002 and 1964-1992, respectively. Seven different pathological changes were found: adonti, displacement of teeth, caries, osseous proliferations, exostosis, tooth wear and periodontitis. Only tooth wear and periodontitis was in a prevalence that allowed statistical treatment. The most severe cases of tooth wear and periodontitis were accompanied by a substantial loss of alveolar bone structure. The prevalence of tooth wear and periodontitis increased significantly with age (p < 0.001) with incisor wear being more severe than in canines, premolars and molars (p < 0.001). No sex difference was found for tooth wear (p = 0.22) while a significant difference between sexes was found for periodontitis (p = 0.01) with males having higher prevalence than females (odds ratio of 2.5 for males:females). In East Greenland, the prevalence of tooth wear was significantly higher in polar bears collected in the pre pollution period (< 1960) than in bears sampled during polluted periods (1960-1980 and 1981-2002) (p < 0.001). Regarding periodontitis, the prevalence was not significantly different between pre-pollution and pollution periods (p = 0.309). Polar bears from Svalbard had significantly higher prevalence of tooth wear (p < 0.001) and periodontitis (p = 0.02) than polar bears from East Greenland. The tooth wear and periodontitis odds ratios for Svalbard:East Greenland were 135 and 2.6, respectively. Hence, we found a clear age/sex link and geographical difference but no evidence for an association between skull pathology and exposure to organochlorines in East Greenland and Svalbard polar bears.

  14. Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century.

    Science.gov (United States)

    Castro de la Guardia, Laura; Derocher, Andrew E; Myers, Paul G; Terwisscha van Scheltinga, Arjen D; Lunn, Nick J

    2013-09-01

    The primary habitat of polar bears is sea ice, but in Western Hudson Bay (WH), the seasonal ice cycle forces polar bears ashore each summer. Survival of bears on land in WH is correlated with breakup and the ice-free season length, and studies suggest that exceeding thresholds in these variables will lead to large declines in the WH population. To estimate when anthropogenic warming may have progressed sufficiently to threaten the persistence of polar bears in WH, we predict changes in the ice cycle and the sea ice concentration (SIC) in spring (the primary feeding period of polar bears) with a high-resolution sea ice-ocean model and warming forced with 21st century IPCC greenhouse gas (GHG) emission scenarios: B1 (low), A1B (medium), and A2 (high). We define critical years for polar bears based on proposed thresholds in breakup and ice-free season and we assess when ice-cycle conditions cross these thresholds. In the three scenarios, critical years occur more commonly after 2050. From 2001 to 2050, 2 critical years occur under B1 and A2, and 4 under A1B; from 2051 to 2100, 8 critical years occur under B1, 35 under A1B and 41 under A2. Spring SIC in WH is high (>90%) in all three scenarios between 2001 and 2050, but declines rapidly after 2050 in A1B and A2. From 2090 to 2100, the mean spring SIC is 84 (±7)% in B1, 56 (±26)% in A1B and 20 (±13)% in A2. Our predictions suggest that the habitat of polar bears in WH will deteriorate in the 21st century. Ice predictions in A1B and A2 suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century. © 2013 John Wiley & Sons Ltd.

  15. Performance and utility of satellite telemetry during field studies of free-ranging polar bears in Alaska

    Science.gov (United States)

    Garner, Gerald W.; Amstrup, Steven C.; Douglas, David C.; Gardner, Craig L.; Amlaner, Charles J.

    1989-01-01

    Satellite telemetry technology has been used during field studies of polar bears in Alaska since 1985. A total of 109 Platform Transmitter Terminals (PTT) have been deployed on free-ranging female polar bears that seasonally inhabit waters adjacent to the Alaskan coast. The PTTs transmitted locational and sensor data to TIROS-N polar-orbiting satellites during a duty cycle of 12 hours on/60 hours off in 1985, 1986, and 1987. Expected battery life was 13.8 months, and collars were normally removed and replaced with new or refurbished PTTs at 11-13 month intervals. Duty cycles were altered to 7-8 hours on/64-65 hours off in 1988 to prolong expected battery life to 19-21 months. Sensor data transmitted included PTT internal temperature, short term activity counts recorded at 60 second intervals, and long term activity counts for the preceding 24 or 72-hour period. Early failures of PTTs to fix location (less than 75% of expected battery life) were as high as 53% during 198501986. Subsequent improvements in battery design, including better shock insulation, improved electronic, and an improved battery system have reduced early failures to 27% in 1987-1988. The harsh environment and the degree of abuse observed in recovered collars indicate that an unavoidable failure rate of 8-10% is inherent within 60 days after deployment on polar bears. A total of 18,000 locations and 201,000 sensor messages were received from female polar bears between May 1985 and June 1988. Polar bears that were marked in Alaskan waters have been located as far south as 60°N 168°W, and as far east as 70°N 127°W in the Beaufort Sea. Polar bears in the Beaufort Sea are shared with Canada, while polar bears in the Chukchi and Bering seas are shared with the Soviet Union. The international ranges of the two hypothesized populations have been documented. Satellite telemetry has detailed the large movement patterns of polar bear over these vast areas that were previously not available using other

  16. “It's Just a Matter of Time:” Lessons from Agency and Community Responses to Polar Bear-inflicted Human Injury

    OpenAIRE

    Aimee L Schmidt; Douglas A Clark

    2018-01-01

    Bear-inflicted human injuries or deaths are often widely publicised, controversial, and evoke substantial social responses that articulate public expectations about bear management. In this paper, we examine how local people and management agencies (i.e. Manitoba Conservation, Parks Canada, and the Town of Churchill) responded to a polar bear-inflicted human injury in Churchill, Manitoba, Canada. On November 1st, 2013, two people in Churchill were badly mauled by a polar bear. The incident sh...

  17. Exposure to mixtures of organohalogen contaminants and associative interactions with thyroid hormones in East Greenland polar bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Villanger, Gro D.; Jenssen, Bjørn M.; Fjeldberg, Rita R.

    2011-01-01

    We investigated the multivariate relationships between adipose tissue residue levels of 48 individual organohalogen contaminants (OHCs) and circulating thyroid hormone (TH) levels in polar bears (Ursus maritimus) from East Greenland (1999–2001, n=62), using projection to latent structure (PLS......) regression for four groupings of polar bears; subadults (SubA), adult females with cubs (AdF_N), adult females without cubs (AdF_S) and adult males (AdM). In the resulting significant PLS models for SubA, AdF_N and AdF_S, some OHCs were especially important in explaining variations in circulating TH levels...... that influenced TH levels in the significant PLS models may potentially act through similar mechanisms on the hypothalamic–pituitary–thyroid (HPT) axis, suggesting that both combined effects by dose and response addition and perhaps synergistic potentiation may be a possibility in these polar bears. Statistical...

  18. Changing Arctic Ecosystems: Updated forecast: Reducing carbon dioxide (CO2) emissions required to improve polar bear outlook

    Science.gov (United States)

    Oakley, Karen L.; Atwood, Todd C.; Mugel, Douglas N.; Rode, Karyn D.; Whalen, Mary E.

    2015-01-01

    The Arctic is warming faster than other regions of the world due to the loss of snow and ice, which increases the amount of solar energy absorbed by the region. The most visible consequence has been the rapid decline in sea ice over the last 3 decades-a decline projected to bring long ice-free summers if greenhouse gas (GHG) emissions are not significantly reduced. The polar bear (Ursus maritimus) depends on sea ice over the biologically productive continental shelves of the Arctic Ocean as a platform for hunting seals. In 2008, the U.S. Fish and Wildlife Service listed the polar bear as threatened under the Endangered Species Act (ESA) due to the threat posed by sea ice loss. The polar bear was the first species to be listed due to forecasted population declines from climate change.

  19. Temporal trend of mercury in polar bears (Ursus maritimus) from Svalbard using teeth as a biomonitoring tissue.

    Science.gov (United States)

    Aubail, Aurore; Dietz, Rune; Rigét, Frank; Sonne, Christian; Wiig, Øystein; Caurant, Florence

    2012-01-01

    We examined the use of mercury (Hg) and nitrogen and carbon stable isotopes in teeth of polar bear (Ursus maritimus) from Svalbard as biotracers of temporal changes in Hg pollution exposure between 1964 and 2003. Teeth were regarded as a good matrix of the Hg exposure, and in total 87 teeth of polar bears were analysed. Dental Hg levels ranged from 0.6 to 72.3 ng g(-1) dry weight and increased with age during the first 10 years of life. A decreasing time trend in Hg concentrations was observed over the recent four decades while no temporal changes were found in the stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C). This suggests that the decrease of Hg concentrations over time was more likely due to a lower environmental Hg exposure in this region rather than a shift in the feeding habits of Svalbard polar bears.

  20. “It's Just a Matter of Time:” Lessons from Agency and Community Responses to Polar Bear-inflicted Human Injury

    Directory of Open Access Journals (Sweden)

    Aimee L Schmidt

    2018-01-01

    Full Text Available Bear-inflicted human injuries or deaths are often widely publicised, controversial, and evoke substantial social responses that articulate public expectations about bear management. In this paper, we examine how local people and management agencies (i.e. Manitoba Conservation, Parks Canada, and the Town of Churchill responded to a polar bear-inflicted human injury in Churchill, Manitoba, Canada. On November 1st, 2013, two people in Churchill were badly mauled by a polar bear. The incident shocked the community, highlighted problems such as a lack of bear safety education, and led to reviews of institutional policies for preventing polar bear-human conflicts. We used qualitative analysis methods to describe what is said (about polar bears, about people, and about management and what is done (changes in behaviours and changes in policies/practices when someone is attacked by a polar bear in Churchill. Results show that polar bear management agencies in Churchill respond remarkably well to errors in procedure, but are often unable to address the many underlying systematic drivers of polar bear-human conflict. Hence, managerial reactions to bear-human conflicts are successful at addressing the proximate cause of the problem, but offer few long-term solutions.

  1. Movement of a female polar bear (Ursus maritimus) in the Kara Sea during the summer sea-ice break-up.

    Science.gov (United States)

    Rozhnov, V V; Platonov, N G; Naidenko, S V; Mordvintsev, I N; Ivanov, E A

    2017-01-01

    The polar bear movement trajectory in relation to onset date of the sea-ice break-up was studied in the coastal zone of the Taimyr Peninsula, eastern part of the Kara Sea, using as an example a female polar bear tagged by a radio collar with an Argos satellite transmitter. Analysis of the long-term pattern of ice melting and tracking, by means of satellite telemetry, of the female polar bear who followed the ice-edge outgoing in the north-eastern direction (in summer 2012) suggests that direction of the polar bear movement depends precisely on the direction of the sea-ice cover break-up.

  2. Genome-Wide Search Identifies 1.9 Mb from the Polar Bear Y Chromosome for Evolutionary Analyses.

    Science.gov (United States)

    Bidon, Tobias; Schreck, Nancy; Hailer, Frank; Nilsson, Maria A; Janke, Axel

    2015-05-27

    The male-inherited Y chromosome is the major haploid fraction of the mammalian genome, rendering Y-linked sequences an indispensable resource for evolutionary research. However, despite recent large-scale genome sequencing approaches, only a handful of Y chromosome sequences have been characterized to date, mainly in model organisms. Using polar bear (Ursus maritimus) genomes, we compare two different in silico approaches to identify Y-linked sequences: 1) Similarity to known Y-linked genes and 2) difference in the average read depth of autosomal versus sex chromosomal scaffolds. Specifically, we mapped available genomic sequencing short reads from a male and a female polar bear against the reference genome and identify 112 Y-chromosomal scaffolds with a combined length of 1.9 Mb. We verified the in silico findings for the longer polar bear scaffolds by male-specific in vitro amplification, demonstrating the reliability of the average read depth approach. The obtained Y chromosome sequences contain protein-coding sequences, single nucleotide polymorphisms, microsatellites, and transposable elements that are useful for evolutionary studies. A high-resolution phylogeny of the polar bear patriline shows two highly divergent Y chromosome lineages, obtained from analysis of the identified Y scaffolds in 12 previously published male polar bear genomes. Moreover, we find evidence of gene conversion among ZFX and ZFY sequences in the giant panda lineage and in the ancestor of ursine and tremarctine bears. Thus, the identification of Y-linked scaffold sequences from unordered genome sequences yields valuable data to infer phylogenomic and population-genomic patterns in bears. © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  3. Genome-Wide Search Identifies 1.9 Mb from the Polar Bear Y Chromosome for Evolutionary Analyses

    Science.gov (United States)

    Bidon, Tobias; Schreck, Nancy; Hailer, Frank; Nilsson, Maria A.; Janke, Axel

    2015-01-01

    The male-inherited Y chromosome is the major haploid fraction of the mammalian genome, rendering Y-linked sequences an indispensable resource for evolutionary research. However, despite recent large-scale genome sequencing approaches, only a handful of Y chromosome sequences have been characterized to date, mainly in model organisms. Using polar bear (Ursus maritimus) genomes, we compare two different in silico approaches to identify Y-linked sequences: 1) Similarity to known Y-linked genes and 2) difference in the average read depth of autosomal versus sex chromosomal scaffolds. Specifically, we mapped available genomic sequencing short reads from a male and a female polar bear against the reference genome and identify 112 Y-chromosomal scaffolds with a combined length of 1.9 Mb. We verified the in silico findings for the longer polar bear scaffolds by male-specific in vitro amplification, demonstrating the reliability of the average read depth approach. The obtained Y chromosome sequences contain protein-coding sequences, single nucleotide polymorphisms, microsatellites, and transposable elements that are useful for evolutionary studies. A high-resolution phylogeny of the polar bear patriline shows two highly divergent Y chromosome lineages, obtained from analysis of the identified Y scaffolds in 12 previously published male polar bear genomes. Moreover, we find evidence of gene conversion among ZFX and ZFY sequences in the giant panda lineage and in the ancestor of ursine and tremarctine bears. Thus, the identification of Y-linked scaffold sequences from unordered genome sequences yields valuable data to infer phylogenomic and population-genomic patterns in bears. PMID:26019166

  4. Seasonal and annual movements of radio-collared polar bears ( Ursus maritimus) in northeast Greenland

    Science.gov (United States)

    Born, E. W.; Wiig, Ø.; Thomassen, J.

    1997-01-01

    The distribution and movements of polar bears ( Ursus maritimus) in the Northeast Water (NEW) area (NE Greenland) were studied from 28 May 1993 to 31 May 1995, using satellite telemetry. Between 28 May and 17 June 1993 satellite-linked radio transmitters were attached to eight adult females in the NEW area between approximately 79° and approximately 80°30'N. By 31 May 1995 the mean duration of transmission (excluding one radio that quit on day of attachment) was 688.4 days (SD = 65.1, range: 541-718 days). These seven females generally showed a high degree of fidelity to the area between 78° and 81°N and 10°W and the northeast Greenland coast. The average distance between capture site in 1993 and spring relocation site in 1994 and 1995 was 116.5 km (SD = 81.9, range: 3.8-210.7 km, N = 7) and 85.4 km (SD = 35.4, range: 38.7-121.8 km, N = 5), respectively. The minimum polygon home range estimates averaged 72,263 km 2 (SD = 71,059, range: 5,567-195,648 km 2, N = 7). Relocations were concentrated on the shore-fast ice and on the pack ice over the continental shelf. This local movement pattern may be facilitated by an anticyclonal gyre of the surface water between 78° and 81°N, and a slowing of the south-flowing East Greenland current. A male bear marked in 1993 at the NEW was taken by hunters in Scoresby Sund (approximately 70°N) in February 1995, indicating that some exchange does occur with southern areas of eastern Greenland. Maternity and temporary dens were located on the coast close to the NEW. Apparently the NEW area is suitable polar bear habitat, in that the bears have access to ringed seals on the fast ice, and on pack ice adjacent to the polynya.

  5. Density, distribution, and genetic structure of grizzly bears in the Cabinet-Yaak Ecosystem

    Science.gov (United States)

    Macleod, Amy C.; Boyd, Kristina L.; Boulanger, John; Royle, J. Andrew; Kasworm, Wayne F.; Paetkau, David; Proctor, Michael F.; Annis, Kim; Graves, Tabitha A.

    2016-01-01

    The conservation status of the 2 threatened grizzly bear (Ursus arctos) populations in the Cabinet-Yaak Ecosystem (CYE) of northern Montana and Idaho had remained unchanged since designation in 1975; however, the current demographic status of these populations was uncertain. No rigorous data on population density and distribution or analysis of recent population genetic structure were available to measure the effectiveness of conservation efforts. We used genetic detection data from hair corral, bear rub, and opportunistic sampling in traditional and spatial capture–recapture models to generate estimates of abundance and density of grizzly bears in the CYE. We calculated mean bear residency on our sampling grid from telemetry data using Huggins and Pledger models to estimate the average number of bears present and to correct our superpopulation estimates for lack of geographic closure. Estimated grizzly bear abundance (all sex and age classes) in the CYE in 2012 was 48–50 bears, approximately half the population recovery goal. Grizzly bear density in the CYE (4.3–4.5 grizzly bears/1,000 km2) was among the lowest of interior North American populations. The sizes of the Cabinet (n = 22–24) and Yaak (n = 18–22) populations were similar. Spatial models produced similar estimates of abundance and density with comparable precision without requiring radio-telemetry data to address assumptions of geographic closure. The 2 populations in the CYE were demographically and reproductively isolated from each other and the Cabinet population was highly inbred. With parentage analysis, we documented natural migrants to the Cabinet and Yaak populations by bears born to parents in the Selkirk and Northern Continental Divide populations. These events supported data from other sources suggesting that the expansion of neighboring populations may eventually help sustain the CYE populations. However, the small size, isolation, and inbreeding documented by this study

  6. Microsatellite DNA and mitochondrial DNA variation in polar bears (Ursus maritimus) from the Beaufort and Chukchi seas, Alaska

    Science.gov (United States)

    Cronin, M.A.; Amstrup, Steven C.; Scribner, K.T.

    2006-01-01

    Radiotelemetry data have shown that polar bears (Ursus maritimus Phipps, 1774) occur in separate subpopulations in the Chukchi Sea and the southern Beaufort Sea. However, segregation is not absolute, and there is overlap of ranges of animals in each subpopulation. We used genetic variation at eight microsatellite DNA loci and mitochondrial DNA (mtDNA) to further assess the degree of spatial structure of polar bears from the Chukchi and southern Beaufort seas. Microsatellite allele frequencies and mtDNA haplotype frequencies of bears from the southern Beaufort and Chukchi seas did not differ significantly. Lack of differentiation at both maternally inherited mtDNA and bi-parentally inherited microsatellite loci suggests that gene flow between the two areas is mediated by both sexes. The genetic data indicate that polar bears in the southern Beaufort and Chukchi seas compose one interbreeding population. However, there is considerable fidelity to ranges in each area, particularly by adult females. The combined genetic and movement data suggest that polar bears could be managed as Beaufort Sea and Chukchi Sea subpopulations of a combined southern Beaufort Sea and Chukchi Sea population. ?? 2006 NRC.

  7. Long-distance swimming by polar bears (Ursus maritimus) of the southern Beaufort Sea during years of extensive open water

    Science.gov (United States)

    2014-01-01

    Polar bears (Ursus maritimus Phipps, 1774) depend on sea ice for catching marine mammal prey. Recent sea-ice declines have been linked to reductions in body condition, survival, and population size. Reduced foraging opportunity is hypothesized to be the primary cause of sea-ice-linked declines, but the costs of travel through a deteriorated sea-ice environment also may be a factor. We used movement data from 52 adult female polar bears wearing Global Positioning System (GPS) collars, including some with dependent young, to document long-distance swimming (>50 km) by polar bears in the southern Beaufort and Chukchi seas. During 6 years (2004-2009), we identified 50 long-distance swims by 20 bears. Swim duration and distance ranged from 0.7 to 9.7 days (mean = 3.4 days) and 53.7 to 687.1 km (mean = 154.2 km), respectively. Frequency of swimming appeared to increase over the course of the study. We show that adult female polar bears and their cubs are capable of swimming long distances during periods when extensive areas of open water are present. However, long-distance swimming appears to have higher energetic demands than moving over sea ice. Our observations suggest long-distance swimming is a behavioral response to declining summer sea-ice conditions.

  8. Non-invasive detection of candidate pregnancy protein biomarkers in the feces of captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Curry, E; Stoops, M A; Roth, T L

    2012-07-15

    Currently, there is no method of accurately and non-invasively diagnosing pregnancy in polar bears. Specific proteins may exhibit altered profiles in the feces of pregnant bears, but predicting appropriate candidate proteins to investigate is speculative at best. The objective of this study was to identify potential pregnancy biomarker proteins based on their increased abundance in the feces of pregnant polar bears compared to pseudopregnant females (controls) using two-dimensional in-gel electrophoresis (2D-DIGE) and mass spectrometry (MS). Three 2D-DIGE gels were performed to evaluate fecal protein profiles from controls (n=3) and pregnant polar bears (n=3). There were 2224.67±52.39 (mean±SEM) spots resolved per gel. Of these, only five proteins were elevated in the pregnant group (P99.9% confidence interval. The 11 spots represented seven distinct proteins, five of which were significantly more abundant in the pregnant group: IgGFc-binding protein, filamin-C, carboxypeptidase B, transthyretin, and immunoglobulin heavy chain variable region. To our knowledge, this was the first study that employed 2D-DIGE to identify differentially expressed proteins in fecal samples to characterize a physiological condition other than those related to gastrointestinal disorders. These promising results provided a strong foundation for ensuing efforts to develop a non-invasive pregnancy assay for use in both captive and wild polar bears. Copyright © 2012 Elsevier Inc. All rights reserved.

  9. Are organohalogen contaminants a bears (Ursus maritimus)?

    DEFF Research Database (Denmark)

    Sonne, Christian; Dietz, Rune; Leifsson, PS

    2006-01-01

    Tissues of polar bears (Ursus maritimus) from East Greenland contain the highest concentrations of organohalogen contaminants (OHCs) among subpopulations of any mammalian species in the Arctic. Negative associations also have been found between OHC concentrations and bone mineral density and liver...... histology parameters for this subpopulation of polar bears. The present study examined the OHC concentrations and adverse effects on renal tissue for 75 polar bears collected during 1999 to 2002. Specific lesions were diffuse glomerular capillary wall thickening, mesangial glomerular deposits, tubular...

  10. Anti-NMDA Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut.

    Science.gov (United States)

    Prüss, H; Leubner, J; Wenke, N K; Czirják, G Á; Szentiks, C A; Greenwood, A D

    2015-08-27

    Knut the polar bear of the Berlin Zoological Garden drowned in 2011 following seizures and was diagnosed as having suffered encephalitis of unknown etiology after exhaustive pathogen screening. Using the diagnostic criteria applied to human patients, we demonstrate that Knut's encephalitis is almost identical to anti-NMDA receptor encephalitis which is a severe autoimmune disease representing the most common non-infectious encephalitis in humans. High concentrations of antibodies specific against the NR1 subunit of the NMDA receptor were detected in Knut's cerebrospinal fluid. Histological examination demonstrated very similar patterns of plasma cell infiltration and minimal neuronal loss in affected brain areas. We conclude that Knut suffered anti-NMDA receptor encephalitis making his the first reported non-human case of this treatable disease. The results suggest that anti-NMDA receptor encephalitis may be a disease of broad relevance to mammals that until now has remained undiagnosed.

  11. Trap array configuration influences estimates and precision of black bear density and abundance.

    Directory of Open Access Journals (Sweden)

    Clay M Wilton

    Full Text Available Spatial capture-recapture (SCR models have advanced our ability to estimate population density for wide ranging animals by explicitly incorporating individual movement. Though these models are more robust to various spatial sampling designs, few studies have empirically tested different large-scale trap configurations using SCR models. We investigated how extent of trap coverage and trap spacing affects precision and accuracy of SCR parameters, implementing models using the R package secr. We tested two trapping scenarios, one spatially extensive and one intensive, using black bear (Ursus americanus DNA data from hair snare arrays in south-central Missouri, USA. We also examined the influence that adding a second, lower barbed-wire strand to snares had on quantity and spatial distribution of detections. We simulated trapping data to test bias in density estimates of each configuration under a range of density and detection parameter values. Field data showed that using multiple arrays with intensive snare coverage produced more detections of more individuals than extensive coverage. Consequently, density and detection parameters were more precise for the intensive design. Density was estimated as 1.7 bears per 100 km2 and was 5.5 times greater than that under extensive sampling. Abundance was 279 (95% CI = 193-406 bears in the 16,812 km2 study area. Excluding detections from the lower strand resulted in the loss of 35 detections, 14 unique bears, and the largest recorded movement between snares. All simulations showed low bias for density under both configurations. Results demonstrated that in low density populations with non-uniform distribution of population density, optimizing the tradeoff among snare spacing, coverage, and sample size is of critical importance to estimating parameters with high precision and accuracy. With limited resources, allocating available traps to multiple arrays with intensive trap spacing increased the amount of

  12. Trap array configuration influences estimates and precision of black bear density and abundance.

    Science.gov (United States)

    Wilton, Clay M; Puckett, Emily E; Beringer, Jeff; Gardner, Beth; Eggert, Lori S; Belant, Jerrold L

    2014-01-01

    Spatial capture-recapture (SCR) models have advanced our ability to estimate population density for wide ranging animals by explicitly incorporating individual movement. Though these models are more robust to various spatial sampling designs, few studies have empirically tested different large-scale trap configurations using SCR models. We investigated how extent of trap coverage and trap spacing affects precision and accuracy of SCR parameters, implementing models using the R package secr. We tested two trapping scenarios, one spatially extensive and one intensive, using black bear (Ursus americanus) DNA data from hair snare arrays in south-central Missouri, USA. We also examined the influence that adding a second, lower barbed-wire strand to snares had on quantity and spatial distribution of detections. We simulated trapping data to test bias in density estimates of each configuration under a range of density and detection parameter values. Field data showed that using multiple arrays with intensive snare coverage produced more detections of more individuals than extensive coverage. Consequently, density and detection parameters were more precise for the intensive design. Density was estimated as 1.7 bears per 100 km2 and was 5.5 times greater than that under extensive sampling. Abundance was 279 (95% CI = 193-406) bears in the 16,812 km2 study area. Excluding detections from the lower strand resulted in the loss of 35 detections, 14 unique bears, and the largest recorded movement between snares. All simulations showed low bias for density under both configurations. Results demonstrated that in low density populations with non-uniform distribution of population density, optimizing the tradeoff among snare spacing, coverage, and sample size is of critical importance to estimating parameters with high precision and accuracy. With limited resources, allocating available traps to multiple arrays with intensive trap spacing increased the amount of information

  13. Issues of choice and control in the behaviour of a pair of captive polar bears (Ursus maritimus).

    Science.gov (United States)

    Ross, Stephen R

    2006-07-01

    Stereotyped behaviour occurs in a wide variety of captive animals including ursids. The provision of animal control over aspects of their environment by providing choices is a critical element for improving welfare. The behaviour of two sibling polar bears at a metropolitan zoo was examined to investigate the effect of providing access to their indoor, off-exhibit holding space. Both bears demonstrated behavioural changes when given the choice to access their indoor dens including decreased stereotyped behaviours and increased social play. These results, although based on just two bears, provide additional support for the assertion that choice and control are closely tied to issues of well-being for captive animals.

  14. Paraparesis in a polar bear (Ursus maritimus) associated with West Nile virus infection.

    Science.gov (United States)

    Dutton, Christopher J; Quinnell, Mark; Lindsay, Robbin; DeLay, Josepha; Barker, Ian K

    2009-09-01

    A polar bear (Ursus maritimus) housed at the Toronto Zoo presented with acute-onset, nonambulatory paraparesis. Physical examination 24 hr after onset was otherwise unremarkable, spinal radiographs looked normal, and blood tests indicated mild dehydration. With continued deterioration in its general condition, euthanasia was elected a day later. Necropsy did not reveal a cause for the major presenting clinical signs. Serum collected at the time of initial examination was positive for West Nile virus (WNV) antibodies in a serum neutralization assay and at the time of euthanasia was positive in both a competitive enzyme-linked immunosorbent assay and in a plaque reduction neutralization assay. The major microscopic finding was a mild-to-moderate nonsuppurative meningoencephalomyelitis. WNV was not detected by immunohistochemistry in brain or spinal cord or by real-time reverse transcription-polymerase chain reaction (RT-PCR) and cell culture of brain and kidney, but it was isolated and identified by RT-PCR in second passage cell culture of spleen. Retrospective immunohistochemistry on spleen revealed rare antigen-positive cells, probably macrophages. Prevention of exposure to potentially WNV-infected mosquitoes or vaccination of captive bears against WNV should be considered.

  15. Polar bear mother-offspring interactions in maternity dens in captivity.

    Science.gov (United States)

    van Gessel, Chad

    2015-01-01

    Two female polar bears at Dierenrijk Zoo in the Netherlands were monitored at their maternity den one day before the birth of their cubs and three days postpartum. Each bear was monitored for 96 hr to document behaviour and vocalisations. The goal was to obtain insight into the differences between the mother that lost her litter and the other that successfully reared her cubs. Six groups of cub vocalisations were identified: Comfort, Discomfort, Distress, Nursing Attempts, Nursing, and No Vocalisation. Maternal vocalisations were split into three groups: Calm, Grooming, and Stress. Maternal behaviours were also split into three groups: Active, Rest, and Stress. The unsuccessful mother produced more stress vocalisations before and during the birth of her cub, whereas the successful mother appeared less stressed. Vocalisations indicate that the cub that died tried to nurse but was unsuccessful. The unsuccessful mother showed less stress as her cub got weaker and vocalised less. From this I suggest that maternal stress was a factor in cub mortality. © 2015 Wiley Periodicals, Inc.

  16. Genetic variation, relatedness, and effective population size of polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska

    Science.gov (United States)

    Cronin, Matthew A.; Amstrup, Steven C.; Talbot, Sandra L.; Sage, George K.; Amstrup, Kristin S.

    2009-01-01

    Polar bears (Ursus maritimus) are unique among bears in that they are adapted to the Arctic sea ice environment. Genetic data are useful for understanding their evolution and can contribute to management. We assessed parentage and relatedness of polar bears in the southern Beaufort Sea, Alaska, with genetic data and field observations of age, sex, and mother–offspring and sibling relationships. Genotypes at 14 microsatellite DNA loci for 226 bears indicate that genetic variation is comparable to other populations of polar bears with mean number of alleles per locus of 7.9 and observed and expected heterozygosity of 0.71. The genetic data verified 60 field-identified mother–offspring pairs and identified 10 additional mother–cub pairs and 48 father–offspring pairs. The entire sample of related and unrelated bears had a mean pairwise relatedness index (rxy) of approximately zero, parent–offspring and siblings had rxy of approximately 0.5, and 5.2% of the samples had rxy values within the range expected for parent-offspring. Effective population size (Ne= 277) and the ratio of Ne to total population size (Ne/N = 0.182) were estimated from the numbers of reproducing males and females. Ne estimates with genetic methods gave variable results. Our results verify and expand field data on reproduction by females and provide new data on reproduction by males and estimates of relatedness and Ne in a polar bear population.

  17. Genetic variation, relatedness, and effective population size of polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska.

    Science.gov (United States)

    Cronin, Matthew A; Amstrup, Steven C; Talbot, Sandra L; Sage, George K; Amstrup, Kristin S

    2009-01-01

    Polar bears (Ursus maritimus) are unique among bears in that they are adapted to the Arctic sea ice environment. Genetic data are useful for understanding their evolution and can contribute to management. We assessed parentage and relatedness of polar bears in the southern Beaufort Sea, Alaska, with genetic data and field observations of age, sex, and mother-offspring and sibling relationships. Genotypes at 14 microsatellite DNA loci for 226 bears indicate that genetic variation is comparable to other populations of polar bears with mean number of alleles per locus of 7.9 and observed and expected heterozygosity of 0.71. The genetic data verified 60 field-identified mother-offspring pairs and identified 10 additional mother-cub pairs and 48 father-offspring pairs. The entire sample of related and unrelated bears had a mean pairwise relatedness index (r(xy)) of approximately zero, parent-offspring and siblings had r(xy) of approximately 0.5, and 5.2% of the samples had r(xy) values within the range expected for parent-offspring. Effective population size (N(e) = 277) and the ratio of N(e) to total population size (N(e)/N = 0.182) were estimated from the numbers of reproducing males and females. N(e) estimates with genetic methods gave variable results. Our results verify and expand field data on reproduction by females and provide new data on reproduction by males and estimates of relatedness and N(e) in a polar bear population.

  18. Vibrational characteristics of a superconducting magnetic bearing employed for a prototype polarization modulator

    Science.gov (United States)

    Sakurai, Yuki; Matsumura, Tomotake; Sugai, Hajime; Katayama, Nobuhiko; Ohsaki, Hiroyuki; Terao, Yutaka; Terachi, Yusuke; Kataza, Hirokazu; Utsunomiya, Shin; Yamamoto, Ryo

    2017-07-01

    We present the vibrational characteristics of a levitating rotor in a superconducting magnetic bearing (SMB) system operating at below 10 K. We develop a polarization modulator that requires a continuously rotating optical element, called half-wave plate (HWP), for a cosmic microwave background polarization experiment. The HWP has to operate at the temperature below 10 K, and thus an SMB provides a smooth rotation of the HWP at the cryogenic temperature of about 10 K with minimal heat dissipation. In order to understand the potential interference to the cosmological observations due to the vibration of the HWP, it is essential to characterize the vibrational properties of the levitating rotor of the SMB. We constructed a prototype model that consists of an SMB with an array of high temperature superconductors, YBCO, and a permanent magnet ring, NdFeB. The rotor position is monitored by a laser displacement gauge, and a cryogenic Hall sensor via the magnetic field. In this presentation, we present the measurement results of the vibration characteristics using our prototype SMB system. We characterize the vibrational properties as the spring constant and the damping, and discuss the projected performance of this technology toward the use in future space missions.

  19. Acute Chagas' cardiopathy in a polar bear (Ursus maritimus in Guadalajara, Mexico

    Directory of Open Access Journals (Sweden)

    J. Jaime-Andrade G.

    1997-08-01

    Full Text Available We report a 24 year old female polar bear (Ursus maritimus who contracted Chagas' infection at the Guadalajara Zoo, in Jalisco, México, and died of acute Chagas' carditis 15 days later. The histopathological findings are described, as well as the presence of triatomines (Triatoma longipennis Usinger infected with Trypanosoma cruzi collected within 5 meters from the place where the animal lived in the city of Guadalajara.Relatamos o caso de uma ursa polar (Ursus maritimus de 24 anos de idade, que contraiu a infecção chagásica no Zoológico de Guadalajara, em Jalisco, no México, e morreu de cardite chagásica aguda 15 dias após o início da sintomatologia. Os achados histopatológicos são descritos, bem como a presença de triatomíneos (Triatoma longipennis Usinger infectados por Trypanosoma cruzi coletados a 5 metros do local onde o animal vivia, na cidade de Guadalajara.

  20. Mark-recapture using tetracycline and genetics reveal record-high bear density

    Science.gov (United States)

    Peacock, E.; Titus, K.; Garshelis, D.L.; Peacock, M.M.; Kuc, M.

    2011-01-01

    We used tetracycline biomarking, augmented with genetic methods to estimate the size of an American black bear (Ursus americanus) population on an island in Southeast Alaska. We marked 132 and 189 bears that consumed remote, tetracycline-laced baits in 2 different years, respectively, and observed 39 marks in 692 bone samples subsequently collected from hunters. We genetically analyzed hair samples from bait sites to determine the sex of marked bears, facilitating derivation of sex-specific population estimates. We obtained harvest samples from beyond the study area to correct for emigration. We estimated a density of 155 independent bears/100 km2, which is equivalent to the highest recorded for this species. This high density appears to be maintained by abundant, accessible natural food. Our population estimate (approx. 1,000 bears) could be used as a baseline and to set hunting quotas. The refined biomarking method for abundance estimation is a useful alternative where physical captures or DNA-based estimates are precluded by cost or logistics. Copyright ?? 2011 The Wildlife Society.

  1. Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer

    Science.gov (United States)

    Harlow, Henry J.; Durner, George M.; Regehr, Eric V.; Rourke, Bryan C.; Robles, Manuel; Amstrup, Steven C.; Ben-David, Merav

    2017-01-01

    Abstract When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions during hibernation. Polar bears may be food deprived and relatively inactive during winter (when pregnant females hibernate and hunting success declines for other demographic groups) as well as summer (when sea ice retreats from key foraging habitats). We investigated muscle atrophy in samples of biceps femoris collected from free-ranging polar bears in the Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced in April–May as a result of food deprivation during the previous winter, with muscles exhibiting reduced protein concentration, increased water content, and lower creatine kinase mRNA. These animals increased feeding and activity in spring (when seal prey becomes more available), initiating a period of muscle recovery. During the following ice melt of late summer, ~30% of SBS bears abandon retreating sea ice for land; in August, these ‘shore’ bears exhibited no muscle atrophy, indicating that they had fully recovered from winter food deprivation. These individuals subsequently scavenged whale carcasses deposited by humans and by October, had retained good muscle condition. In contrast, ~70% of SBS bears follow the ice north in late summer, into deep water with less prey. These ‘ice’ bears fast; by October, they exhibited muscle protein loss and rapid changes in myosin heavy-chain isoforms in response to reduced activity. These findings indicate that, unlike other bears during winter hibernation, polar bears without food in summer cannot mitigate atrophy. Consequently, prolonged summer fasting resulting from climate change-induced ice loss creates a risk of greater muscle atrophy and reduced abilities to travel and hunt. PMID:28835844

  2. Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer

    Science.gov (United States)

    Whiteman, John P.; Harlow, Henry J.; Durner, George M.; Regehr, Eric V.; Rourke, Bryan C.; Robles, Manuel; Amstrup, Steven C.; Ben-David, Merav

    2017-01-01

    When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions during hibernation. Polar bears may be food deprived and relatively inactive during winter (when pregnant females hibernate and hunting success declines for other demographic groups) as well as summer (when sea ice retreats from key foraging habitats). We investigated muscle atrophy in samples of biceps femoris collected from free-ranging polar bears in the Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced in April–May as a result of food deprivation during the previous winter, with muscles exhibiting reduced protein concentration, increased water content, and lower creatine kinase mRNA. These animals increased feeding and activity in spring (when seal prey becomes more available), initiating a period of muscle recovery. During the following ice melt of late summer, ~30% of SBS bears abandon retreating sea ice for land; in August, these ‘shore’ bears exhibited no muscle atrophy, indicating that they had fully recovered from winter food deprivation. These individuals subsequently scavenged whale carcasses deposited by humans and by October, had retained good muscle condition. In contrast, ~70% of SBS bears follow the ice north in late summer, into deep water with less prey. These ‘ice’ bears fast; by October, they exhibited muscle protein loss and rapid changes in myosin heavy-chain isoforms in response to reduced activity. These findings indicate that, unlike other bears during winter hibernation, polar bears without food in summer cannot mitigate atrophy. Consequently, prolonged summer fasting resulting from climate change-induced ice loss creates a risk of greater muscle atrophy and reduced abilities to travel and hunt.

  3. Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer.

    Science.gov (United States)

    Whiteman, John P; Harlow, Henry J; Durner, George M; Regehr, Eric V; Rourke, Bryan C; Robles, Manuel; Amstrup, Steven C; Ben-David, Merav

    2017-01-01

    When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions during hibernation. Polar bears may be food deprived and relatively inactive during winter (when pregnant females hibernate and hunting success declines for other demographic groups) as well as summer (when sea ice retreats from key foraging habitats). We investigated muscle atrophy in samples of biceps femoris collected from free-ranging polar bears in the Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced in April-May as a result of food deprivation during the previous winter, with muscles exhibiting reduced protein concentration, increased water content, and lower creatine kinase mRNA. These animals increased feeding and activity in spring (when seal prey becomes more available), initiating a period of muscle recovery. During the following ice melt of late summer, ~30% of SBS bears abandon retreating sea ice for land; in August, these 'shore' bears exhibited no muscle atrophy, indicating that they had fully recovered from winter food deprivation. These individuals subsequently scavenged whale carcasses deposited by humans and by October, had retained good muscle condition. In contrast, ~70% of SBS bears follow the ice north in late summer, into deep water with less prey. These 'ice' bears fast; by October, they exhibited muscle protein loss and rapid changes in myosin heavy-chain isoforms in response to reduced activity. These findings indicate that, unlike other bears during winter hibernation, polar bears without food in summer cannot mitigate atrophy. Consequently, prolonged summer fasting resulting from climate change-induced ice loss creates a risk of greater muscle atrophy and reduced abilities to travel and hunt.

  4. Interplay between spin polarization and color superconductivity in high density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança

    2013-01-01

    Here, it is suggested that a four-point interaction of the tensor type may lead to spin polarization in quark matter at high density. It is found that the two-flavor superconducting phase and the spin polarized phase correspond to distinct local minima of a certain generalized thermodynamical...... potential. It follows that a transition from one to the other phase occurs, passing through true minima with both a spin polarization and a color superconducting gap. It is shown that the quark spin polarized phase is realized at rather high density, while the two-flavor color superconducting phase...

  5. Population genetic studies of the polar bear (Ursus maritimus): A summary of available data and interpretation of results

    Science.gov (United States)

    Scribner, Kim T.; Garner, G.W.; Amstrup, Steven C.; Cronin, M.A.; Dizon, Andrew E.; Chivers, Susan J.; Perrin, William F.

    1997-01-01

    A summary of existing population genetics literature is presented for polar bears (Ursus maritimus) and interpreted in the context of the species' life-history characteristics and regional heterogeneity in environmental regimes and movement patterns. Several nongenetic data sets including morphology, contaminant levels, geographic variation in reproductive characteristics, and the location and distribution of open-water foraging habitat suggest some degree of spatial structuring. Eleven populations are recognized by the IUCN Polar Bear Specialist Group. Few genetics studies exist for polar bears. Interpretation and generalizations of regional variation in intra- and interpopulation levels of genetic variability are confounded by the paucity of data from many regions and by the fact that no single informative genetic marker has been employed in multiple regions. Early allozyme studies revealed comparatively low levels of genetic variability and no compelling evidence of spatial structuring. Studies employing mitochondrial DNA (mtDNA) also found low levels of genetic variation, a lack of phylogenetic structure, and no significant evidence for spatial variation in haplotype frequency. In contrast, microsatellite variable number of tandem repeat (VNTR) loci have revealed significant heterogeneity in allele frequency among populations in the Canadian Arctic. These regions are characterized by archipelgic patterns of sea-ice movements. Further studies using highly polymorphic loci are needed in regions characterized by greater polar bear dependency on pelagic sea-ice movements and in regions for which no data currently exist (i.e., Laptev and Novaya Zemlya/Franz Josef).

  6. Perfluoroalkyl substances in polar bear mother-cub pairs: A comparative study based on plasma levels from 1998 and 2008

    NARCIS (Netherlands)

    Bytingsvik, J.; Leeuwen, S.; Hamers, T.; Swart, C.P.; Aars, J.; Lie, E.; Espseth Nilsen, E.M.; Wiig, O.; Derocher, A. E.; Jenssen, B.M.

    2012-01-01

    Perfluoroalkyl substances (PFASs) are protein-binding blood-accumulating contaminants that may have detrimental toxicological effects on the early phases of mammalian development. To enable an evaluation of the potential health risks of PFAS exposure for polar bears (Ursus maritimus), an exposure

  7. Identification of 4-hydroxyheptachlorostyrene in polar bear plasma and its binding affinity to transthyretin : a metabolite of octachlorostyrene?

    NARCIS (Netherlands)

    Standau, C.D.; Meerts, I.A.T.M.; Letcher, R.J.; McAlees, A.J.; Chittim, B.; Brouwer, A.; Norstrom, R.J.

    2000-01-01

    A new compound, 4-hydroxyheptachlorostyrene (4-OH-HpCS), was identified as a major component in the chlorinated phenolic compound fraction of polar bear plasma. The structure was hypothesized to be 4-OH-HpCS based on mass spectral interpretation, the assumption that it was a metabolite of

  8. Identification of 4-hydroxyheptachlorostyrene in polar bear plasma and its binding affinity to transhyretin: a metabolite of octachlorostyrene

    NARCIS (Netherlands)

    Sandau, C.D.; Meerts, I.A.T.M.; Letcher, R.J.; McAlee, A.J.; Chittim, B.; Brouwer, A.; Norstrom, R.J.

    2000-01-01

    A new compound, 4-hydroxyheptachlorostyrene (4-OH-HpCS), was identified as a major component in the chlorinated phenolic compound fraction of polar bear plasma. The structure was hypothesized to be 4-OH-HpCS based on mass spectral interpretation, the assumption that it was a metabolite of

  9. Three decades (1983-2010) of contaminant trends in East Greenland polar bears (Ursus maritimus). Part 1: legacy organochlorine contaminants.

    Science.gov (United States)

    Dietz, Rune; Rigét, Frank F; Sonne, Christian; Born, Erik W; Bechshøft, Thea; McKinney, Melissa A; Letcher, Robert J

    2013-09-01

    Legacy organochlorine contaminants were determined in adipose tissues from 294 polar bears (Ursus maritimus) sampled in East Greenland in 23 of the 28years between 1983 and 2010. Of 19 major legacy contaminants and congeners (ΣPCB, 4 PCB congeners (CB153, 180, 170/190), ΣDDT, p,p'-DDE, p,p' -DDD and p,p'-DDT, α- and β-hexachlorocyclohexane (HCH), HCB, octachlorostyrene, dieldrin, oxychlordane, cis- and trans-chlordane, cis- and trans-nonachlor, heptachlor epoxide and BB-153), 18 showed statistically significant average yearly declines of -4.4% (range: -2.0 to -10.8%/year) among subadult polar bears (i.e. femalespolar bear tissues. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Mapping polar bear maternal denning habitat in the National Petroleum Reserve -- Alaska with an IfSAR digital terrain model

    Science.gov (United States)

    Durner, George M.; Simac, Kristin S.; Amstrup, Steven C.

    2013-01-01

    The National Petroleum Reserve–Alaska (NPR-A) in northeastern Alaska provides winter maternal denning habitat for polar bears (Ursus maritimus) and also has high potential for recoverable hydrocarbons. Denning polar bears exposed to human activities may abandon their dens before their young are able to survive the severity of Arctic winter weather. To ensure that wintertime petroleum activities do not threaten polar bears, managers need to know the distribution of landscape features in which maternal dens are likely to occur. Here, we present a map of potential denning habitat within the NPR-A. We used a fine-grain digital elevation model derived from Interferometric Synthetic Aperture Radar (IfSAR) to generate a map of putative denning habitat. We then tested the map’s ability to identify polar bear denning habitat on the landscape. Our final map correctly identified 82% of denning habitat estimated to be within the NPR-A. Mapped denning habitat comprised 19.7 km2 (0.1% of the study area) and was widely dispersed. Though mapping denning habitat with IfSAR data was as effective as mapping with the photogrammetric methods used for other regions of the Alaskan Arctic coastal plain, the use of GIS to analyze IfSAR data allowed greater objectivity and flexibility with less manual labor. Analytical advantages and performance equivalent to that of manual cartographic methods suggest that the use of IfSAR data to identify polar bear maternal denning habitat is a better management tool in the NPR-A and wherever such data may be available.

  11. Comparative fate of organohalogen contaminants in two top carnivores in Greenland: captive sledge dogs and wild polar bears.

    Science.gov (United States)

    Verreault, Jonathan; Dietz, Rune; Sonne, Christian; Gebbink, Wouter A; Shahmiri, Soheila; Letcher, Robert J

    2008-04-01

    The limited knowledge and/or the inability to control physiological condition parameters that influence the fate of organohalogen contaminants (OHCs) has been the foremost confounding aspect in monitoring programs and health risk assessments of wild top predators in the Arctic such as the polar bear (Ursus maritimus). In the present comparative study, we used a potential surrogate Canoidea species for the East Greenland polar bear, the captive sledge dog (Canis familiaris), to investigate some factors that may influence the bioaccumulation and biotransformation of major chlorinated and brominated OHCs in adipose tissue and blood (plasma) of control (fed commercial pork fat) and exposed (fed West Greenland minke whale (Balaenoptera acutorostrata) blubber) adult female sledge dogs. Furthermore, we compared the patterns and concentrations of OHCs and their known or suggested hydroxylated (OH) metabolites (e.g., OH-PCBs) in sledge dogs with those in adipose tissue and blood (plasma) of East Greenland adult female polar bears, and blubber of their main prey species, the ringed seal (Pusa hispida). The two-year feeding regime conducted with sledge dogs led to marked differences in overall adipose tissue (and plasma) OHC residue accumulation between the control and exposed groups. Characteristic prey-to-predator OHC bioaccumulation dynamics for major PCB and PBDE congeners (patterns and concentrations) and biotransformation capacity with respect to PCB metabolite formation and OH-PCB retention distinguished, to some extent, captive sledge dogs and wild polar bears. Based on the present findings, we conclude that the use of surrogate species in toxicological investigations for species in the Canoidea family should be done with great caution, although they remain essential in the context of contaminants research with sensitive arctic top carnivore species such as the polar bear.

  12. Spatial and temporal variation in size of polar bear (Ursus maritimus) sexual organs and its use in pollution and climate change studies.

    Science.gov (United States)

    Sonne, Christian; Dietz, Rune; Born, Erik W; Riget, Frank F; Leifsson, Pall S; Bechshøft, Thea Ø; Kirkegaard, Maja

    2007-11-15

    Sexual organs and their development are susceptible to atmospheric transported environmental xenoendocrine pollutants and climate change (food availability). We therefore investigated sexual organs from 55 male and 44 female East Greenland polar bears (Ursus maritimus) to obtain information about growth/size and sexual maturity. Then, the genitalia size was compared with those previously reported from Canadian and Svalbard polar bears. Growth models showed that East Greenland male polar bears reached sexual maturity around 7 years of age and females around 4 years of age. When comparing East Greenland and Svalbard polar bears, the size of baculum and uterus were significantly lower in the East Greenland polar bears (ANOVA: all p bears, a similar baculum pattern was found for East Greenland vs. Canadian polar bears. It is speculated whether this could be a result of the general high variation in polar bear body size, temporal distribution patterns of anthropogenic long-range transported persistent organic pollutants or climate change (decreasing food availability). The present investigation represents conservation and background data for future spatial and temporal assessments of hunting, pollution and climate change scenarios.

  13. Polar cap hot patches: Enhanced density structures different from the classical patches in the ionosphere

    Science.gov (United States)

    Zhang, Q.-H.; Ma, Y.-Z.; Jayachandran, P. T.; Moen, J.; Lockwood, M.; Zhang, Y.-L.; Foster, J. C.; Zhang, S.-R.; Wang, Y.; Themens, D. R.; Zhang, B.-C.; Xing, Z. Y.

    2017-08-01

    Based on in situ and ground-based observations, a new type of "polar cap hot patch" has been identified that is different from the classical polar cap enhanced density structure (cold patches). Comparing with the classical polar cap patches, which are transported from the dayside sunlit region with dense and cold plasma, the polar cap hot patches are associated with particle precipitations (therefore field-aligned currents), ion upflows, and flow shears. The hot patches may have the same order of density enhancement as classical patches in the topside ionosphere, suggesting that the hot patches may be produced by transported photoionization plasma into flow channels. Within the flow channels, the hot patches have low-energy particle precipitation and/or ion upflows associated with field-aligned currents and flow shears. Corresponding Global Navigation Satellite System (GNSS) signal scintillation measurements indicate that hot patches may produce slightly stronger radio signal scintillation in the polar cap region than classical patches. A new type of polar cap patches, "polar cap hot patches," is identified to differentiate enhanced density structures from classical patches. Hot patches are associated with particle precipitations, ion upflows, field-aligned currents, and shear flows in the polar cap. Hot patches may lead to slightly stronger ionospheric scintillations of GNSS signals in the polar cap region than classical patches.

  14. On the theory of pyro- and ferroelectrics: Dipole moment density and polarization

    Science.gov (United States)

    Belyavskii, V. I.; Gorbatsevich, A. A.

    2017-04-01

    The physical origin of the ambiguity related to the dependence of the polarization on the choice of the unit cell in a crystal is established in the framework of classical electrodynamics. It is shown that the electric polarization of a crystal is determined not only by the charge distribution in the unit cell (dipole moment density) but also by the microscopic mechanism of symmetry breaking in the polar phase. An approach to the calculation of the polarization invariant with respect to the choice of the unit cell is suggested. It is demonstrated that the dependence of the polarization on the mechanism of formation of the polar phase exists in the "modern topological theory" of polarization too.

  15. Variables affecting the manifestation of and intensity of pacing behavior: A preliminary case study in zoo-housed polar bears.

    Science.gov (United States)

    Cless, Isabelle T; Lukas, Kristen E

    2017-09-01

    High-speed video analysis was used to quantify two aspects of gait in 10 zoo-housed polar bears. These two variables were then examined as to how they differed in the conditions of pacing versus locomoting for each bear. Percent difference calculations measured the difference between pacing and locomoting data for each bear. We inferred that the higher the percent difference between pacing and locomoting in a given subject, the more intense the pacing may be. The percent difference values were analyzed alongside caregiver survey data defining the locations, frequency, and anticipatory nature of pacing in each bear, as well as each bear's age and sex, to determine whether any variables were correlated. The frequency and intensity of pacing behavior were not correlated. However, location of pacing was significantly correlated both with the subjects' age and whether or not the subject was classified as an anticipatory pacer. Bears appeared to select specific spots within their exhibits to pace, and the location therefore seemed tied to underlying motivation for the behavior. Additionally, bears that were classified in the survey as pacing anticipatorily displayed significantly more intense pacing behavior as quantified by gait analysis. © 2017 Wiley Periodicals, Inc.

  16. Geographic variation of PCB congeners in polar bears (Ursus maritimus) from Svalbard east to the Chukchi Sea

    Science.gov (United States)

    Andersen, M.; Lie, E.; Derocher, A.E.; Belikov, S.E.; Bernhoft, A.; Boltunov, Andrei N.; Garner, G.W.; Skaare, J.U.; Wiig, Øystein

    2001-01-01

    We present data on geographic variation in polychlorinated biphenyl (PCB) congeners in adult female polar bears (Ursus maritimus) from Svalbard eastward to the Chukchi Sea. Blood samples from 90 free-living polar bears were collected in 1987–1995. Six PCB congeners, penta to octa chlorinated (PCB-99, -118, -153, -156, -180, -194), were selected for this study. Differences between areas were found in PCB levels and congener patterns. Bears from Franz Josef Land (11,194 ng/g lipid weight) and the Kara Sea (9,412 ng/g lw) had similar ΣPCB levels and were higher than all other populations (Svalbard 5,043 ng/g lw, East Siberian Sea 3,564 ng/g lw, Chukchi Sea 2,465 ng/g lw). Svalbard PCB levels were higher than those from the Chukchi Sea. Our results, combined with earlier findings, indicate that polar bears from Franz Josef Land and the Kara Sea have the highest PCB levels in the Arctic. Decreasing trends were seen eastwards and westwards from this region. Of the congeners investigated in the present study, the lower chlorinated PCBs are increasing and the high chlorinated PCBs are decreasing from Svalbard eastward to the Chukchi Sea. Different pollution sources, compound transport patterns and regional prey differences could explain the variation in PCB congener levels and patterns between regions.

  17. Geographic distribution of selected elements in the livers of polar bears from Greenland, Canada and the United States

    Energy Technology Data Exchange (ETDEWEB)

    Rush, Scott A. [University of Georgia, Warnell School of Forestry and Natural Resources, Athens, GA 30602-2152 (United States); Borga, Katrine [Norwegian Institute for Water Research, Gaustadalleen 21, 0349 Oslo (Norway); Dietz, Rune [National Environmental Research Institute, Department of Arctic Environment, Roskilde DK-4000 (Denmark); Born, Erik W. [Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland (Denmark); Sonne, Christian [National Environmental Research Institute, Department of Arctic Environment, Roskilde DK-4000 (Denmark); Evans, Thomas [United States Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK 99503 (United States); Muir, Derek C.G. [Environment Canada, Water Science and Technology Directorate, Burlington, ON L7R 4A6 (Canada); Letcher, Robert J. [Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON K1A 0H3 (Canada); Norstrom, Ross J. [Carleton University, Department of Chemistry, Ottawa, ON K1S 5B6 (Canada); Fisk, Aaron T. [University of Windsor, Great Lakes Institute for Environmental Research, Windsor, ON N9B 3P4 (Canada)], E-mail: afisk@uwindsor.ca

    2008-06-15

    To assess geographic distributions of elements in the Arctic we compared essential and non-essential elements in the livers of polar bears (Ursus maritimus) collected from five regions within Canada in 2002, in Alaska between 1994 and 1999 and from the northwest and east coasts of Greenland between 1988 and 2000. As, Hg, Pb and Se varied with age, and Co and Zn with gender, which limited spatial comparisons across all populations to Cd, which was highest in Greenland bears. Collectively, geographic relationships appeared similar to past studies with little change in concentration over time in Canada and Greenland for most elements; Hg and Se were higher in some Canadian populations in 2002 as compared to 1982 and 1984. Concentrations of most elements in the polar bears did not exceed toxicity thresholds, although Cd and Hg exceeded levels correlated with the formation of hepatic lesions in laboratory animals. - Geographical trends were observed for a number of elements in livers, including mercury, of polar bears collected across Alaska, Canada and Greenland and were similar to those observed in the early 1980s.

  18. Geographic distribution of selected elements in the livers of polar bears from Greenland, Canada and the United States

    International Nuclear Information System (INIS)

    Rush, Scott A.; Borga, Katrine; Dietz, Rune; Born, Erik W.; Sonne, Christian; Evans, Thomas; Muir, Derek C.G.; Letcher, Robert J.; Norstrom, Ross J.; Fisk, Aaron T.

    2008-01-01

    To assess geographic distributions of elements in the Arctic we compared essential and non-essential elements in the livers of polar bears (Ursus maritimus) collected from five regions within Canada in 2002, in Alaska between 1994 and 1999 and from the northwest and east coasts of Greenland between 1988 and 2000. As, Hg, Pb and Se varied with age, and Co and Zn with gender, which limited spatial comparisons across all populations to Cd, which was highest in Greenland bears. Collectively, geographic relationships appeared similar to past studies with little change in concentration over time in Canada and Greenland for most elements; Hg and Se were higher in some Canadian populations in 2002 as compared to 1982 and 1984. Concentrations of most elements in the polar bears did not exceed toxicity thresholds, although Cd and Hg exceeded levels correlated with the formation of hepatic lesions in laboratory animals. - Geographical trends were observed for a number of elements in livers, including mercury, of polar bears collected across Alaska, Canada and Greenland and were similar to those observed in the early 1980s

  19. Concentrations and interactions of selected essential and non-essential elements in ringed seals and polar bears of arctic Alaska.

    Science.gov (United States)

    Woshner, V M; O'Hara, T M; Bratton, G R; Beasley, V R

    2001-10-01

    In this study, we evaluated concentrations of twelve essential and non-essential elements (As, Cd, Co, Cu, Pb, Mg, Mn, Hg, Mo, Se, Ag, and Zn) in tissues of ringed seals (Phoca hispida) and polar bears (Ursus maritimus) of arctic Alaska (USA). All samples were collected between 1995-97 in conjunction with subsistence harvests. The essential elements are reported to help develop reference ranges for health status determination and to help assess known or suspected interactions affecting toxicoses of cadmium (Cd) and mercury (Hg). In some tissues, Cd, Hg, and selenium (Se) were present at concentrations that have been associated with toxicoses in some domestic animals. Nevertheless, tissue levels of all elements were within ranges that have been reported previously in other pinnipeds and polar bears. Significant associations included: Cd with Zn or Cu; Cu with Zn or Ag; and Hg with Se, Zn, or Cu. This study found hepatic Hg:Se molar ratios to be lower than unity and different between the two species. Based upon significant differences in mean tissue elemental concentrations for polar bear versus ringed seal, we concluded that biomagnification factors (bear/seal) were significant for: Cu in liver and muscle; Pb in kidney; Se in kidney and muscle; Zn in liver and muscle; and Hg in liver. Possible explanations for observed elemental correlations (i.e., interactions) and ancillary mechanisms of Cd and Hg detoxification are discussed.

  20. Noise and vibration levels in artificial polar bear dens as related to selected petroleum exploration and developmental activities

    International Nuclear Information System (INIS)

    Blix, A.S.; Lentfer, J.W.

    1992-01-01

    Petroleum exploration and development are occurring in various locations in the Arctic, where there are important denning sites for polar bears. Petroleum activities usually coincide with winter denning activities by bears, who may abandon dens if subject to prolonged annoyance. A study was carried out to measure noise and vibration levels in artificial polar bear dens at Prudhoe's Bar, Alaska, resulting from seismic testing, drilling and transport. A microphone and an accelerometer were frozen to the floor of the dens, with leads passed through a consolidated snow filled entrance to a truck, tent or helicopter. Tests were carried out on land, sea ice, and next to a drilling tower on an artificial island, which was also used to measure noise levels resulting from a helicopter taking off. It was concluded that the dry and wind-beaten arctic snow muffles both sound and vibration extremely well, and it is unlikely that polar bears in their dens will be disturbed by the type of petroleum-related activities measured, provided they do not take place within 100 m of the dens. 8 refs., 7 figs., 1 tab

  1. Phenotypic plasticity and climate change: can polar bears respond to longer Arctic summers with an adaptive fast?

    Science.gov (United States)

    Whiteman, John P; Harlow, Henry J; Durner, George M; Regehr, Eric V; Amstrup, Steven C; Ben-David, Merav

    2018-02-01

    Plasticity in the physiological and behavioural responses of animals to prolonged food shortages may determine the persistence of species under climate warming. This is particularly applicable for species that can "adaptively fast" by conserving protein to protect organ function while catabolizing endogenous tissues. Some Ursids, including polar bears (Ursus maritimus), adaptively fast during winter hibernation-and it has been suggested that polar bears also employ this strategy during summer. We captured 57 adult female polar bears in the Southern Beaufort Sea (SBS) during summer 2008 and 2009 and measured blood variables that indicate feeding, regular fasting, and adaptive fasting. We also assessed tissue δ 13 C and δ 15 N to infer diet, and body condition via mass and length. We found that bears on shore maintained lipid and protein stores by scavenging on bowhead whale (Balaena mysticetus) carcasses from human harvest, while those that followed the retreating sea ice beyond the continental shelf were food deprived. They had low ratios of blood urea to creatinine (U:C), normally associated with adaptive fasting. However, they also exhibited low albumin and glucose (indicative of protein loss) and elevated alanine aminotransferase and ghrelin (which fall during adaptive fasting). Thus, the ~ 70% of the SBS subpopulation that spends summer on the ice experiences more of a regular, rather than adaptive, fast. This fast will lengthen as summer ice declines. The resulting protein loss prior to winter could be a mechanism driving the reported correlation between summer ice and polar bear reproduction and survival in the SBS.

  2. Design of a 9K illumina BeadChip for polar bears (Ursus maritimus) from RAD and transcriptome sequencing.

    Science.gov (United States)

    Malenfant, René M; Coltman, David W; Davis, Corey S

    2015-05-01

    Single-nucleotide polymorphisms (SNPs) offer numerous advantages over anonymous markers such as microsatellites, including improved estimation of population parameters, finer-scale resolution of population structure and more precise genomic dissection of quantitative traits. However, many SNPs are needed to equal the resolution of a single microsatellite, and reliable large-scale genotyping of SNPs remains a challenge in nonmodel species. Here, we document the creation of a 9K Illumina Infinium BeadChip for polar bears (Ursus maritimus), which will be used to investigate: (i) the fine-scale population structure among Canadian polar bears and (ii) the genomic architecture of phenotypic traits in the Western Hudson Bay subpopulation. To this end, we used restriction-site associated DNA (RAD) sequencing from 38 bears across their circumpolar range, as well as blood/fat transcriptome sequencing of 10 individuals from Western Hudson Bay. Six-thousand RAD SNPs and 3000 transcriptomic SNPs were selected for the chip, based primarily on genomic spacing and gene function respectively. Of the 9000 SNPs ordered from Illumina, 8042 were successfully printed, and - after genotyping 1450 polar bears - 5441 of these SNPs were found to be well clustered and polymorphic. Using this array, we show rapid linkage disequilibrium decay among polar bears, we demonstrate that in a subsample of 78 individuals, our SNPs detect known genetic structure more clearly than 24 microsatellites genotyped for the same individuals and that these results are not driven by the SNP ascertainment scheme. Here, we present one of the first large-scale genotyping resources designed for a threatened species. © 2014 John Wiley & Sons Ltd.

  3. Solvent density mode instability in non-polar solutions

    Indian Academy of Sciences (India)

    1Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National. Centre for Basic Sciences, ... upon excitation mainly drives the solvent reorganization [12,13]. However, the. Stokes shifts ..... process [17] where a solvent density mode with momentum q is scattered to another density mode of ...

  4. Prevalence and spatio-temporal variation of an alopecia syndrome in polar bears (Ursus maritimus) of the southern Beaufort Sea

    Science.gov (United States)

    Atwood, Todd C.; Peacock, Elizabeth; Burek, K.A.; Shearn-Bochsler, Valerie I.; Bodenstein, Barbara L.; Beckmen, Kimberlee B.; Durner, George M.

    2015-01-01

    Alopecia (hair loss) has been observed in several marine mammal species and has potential energetic consequences for sustaining a normal core body temperature, especially for Arctic marine mammals routinely exposed to harsh environmental conditions. Polar bears (Ursus maritimus) rely on a thick layer of adipose tissue and a dense pelage to ameliorate convective heat loss while moving between sea ice and open water. From 1998 to 2012, we observed an alopecia syndrome in polar bears from the southern Beaufort Sea of Alaska that presented as bilaterally asymmetrical loss of guard hairs and thinning of the undercoat around the head, neck, and shoulders, which, in severe cases, was accompanied by exudation and crusted skin lesions. Alopecia was observed in 49 (3.45%) of the bears sampled during 1,421 captures, and the apparent prevalence varied by years with peaks occurring in 1999 (16%) and 2012 (28%). The probability that a bear had alopecia was greatest for subadults and for bears captured in the Prudhoe Bay region, and alopecic individuals had a lower body condition score than unaffected individuals. The cause of the syndrome remains unknown and future work should focus on identifying the causative agent and potential effects on population vital rates.

  5. Prevalence and spatio-temporal variation of an alopecia syndrome in polar bears (Ursus maritimus) of the southern Beaufort Sea.

    Science.gov (United States)

    Atwood, Todd; Peacock, Elizabeth; Burek-Huntington, Kathy; Shearn-Bochsler, Valerie; Bodenstein, Barbara; Beckmen, Kimberlee; Durner, George

    2015-01-01

    Alopecia (hair loss) has been observed in several marine mammal species and has potential energetic consequences for sustaining a normal core body temperature, especially for Arctic marine mammals routinely exposed to harsh environmental conditions. Polar bears (Ursus maritimus) rely on a thick layer of adipose tissue and a dense pelage to ameliorate convective heat loss while moving between sea ice and open water. From 1998 to 2012, we observed an alopecia syndrome in polar bears from the southern Beaufort Sea of Alaska that presented as bilaterally asymmetrical loss of guard hairs and thinning of the undercoat around the head, neck, and shoulders, which, in severe cases, was accompanied by exudation and crusted skin lesions. Alopecia was observed in 49 (3.45%) of the bears sampled during 1,421 captures, and the apparent prevalence varied by years with peaks occurring in 1999 (16%) and 2012 (28%). The probability that a bear had alopecia was greatest for subadults and for bears captured in the Prudhoe Bay region, and alopecic individuals had a lower body condition score than unaffected individuals. The cause of the syndrome remains unknown and future work should focus on identifying the causative agent and potential effects on population vital rates.

  6. Diet and metabolic state are the main factors determining concentrations of perfluoroalkyl substances in female polar bears from Svalbard.

    Science.gov (United States)

    Tartu, Sabrina; Bourgeon, Sophie; Aars, Jon; Andersen, Magnus; Lone, Karen; Jenssen, Bjørn Munro; Polder, Anuschka; Thiemann, Gregory W; Torget, Vidar; Welker, Jeffrey M; Routti, Heli

    2017-10-01

    Perfluoroalkyl substances (PFASs) have been detected in organisms worldwide, including Polar Regions. The polar bear (Ursus maritimus), the top predator of Arctic marine ecosystems, accumulates high concentrations of PFASs, which may be harmful to their health. The aim of this study was to investigate which factors (habitat quality, season, year, diet, metabolic state [i.e. feeding/fasting], breeding status and age) predict PFAS concentrations in female polar bears captured on Svalbard (Norway). We analysed two perfluoroalkyl sulfonates (PFSAs: PFHxS and PFOS) and C 8 -C 13 perfluoroalkyl carboxylates (PFCAs) in 112 plasma samples obtained in April and September 2012-2013. Nitrogen and carbon stable isotope ratios (δ 15 N, δ 13 C) in red blood cells and plasma, and fatty acid profiles in adipose tissue were used as proxies for diet. We determined habitat quality based on movement patterns, capture position and resource selection functions, which are models that predict the probability of use of a resource unit. Plasma urea to creatinine ratios were used as proxies for metabolic state (i.e. feeding or fasting state). Results were obtained from a conditional model averaging of 42 general linear mixed models. Diet was the most important predictor of PFAS concentrations. PFAS concentrations were positively related to trophic level and marine diet input. High PFAS concentrations in females feeding on the eastern part of Svalbard, where the habitat quality was higher than on the western coast, were likely related to diet and possibly to abiotic factors. Concentrations of PFSAs and C 8 -C 10 PFCAs were higher in fasting than in feeding polar bears and PFOS was higher in females with cubs of the year than in solitary females. Our findings suggest that female polar bears that are exposed to the highest levels of PFAS are those 1) feeding on high trophic level sea ice-associated prey, 2) fasting and 3) with small cubs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Validation of adipose lipid content as a body condition index for polar bears

    Science.gov (United States)

    McKinney, Melissa A.; Atwood, Todd; Dietz, Rune; Sonne, Christian; Iverson, Sara J.; Peacock, Elizabeth

    2014-01-01

    Body condition is a key indicator of individual and population health. Yet, there is little consensus as to the most appropriate condition index (CI), and most of the currently used CIs have not been thoroughly validated and are logistically challenging. Adipose samples from large datasets of capture biopsied, remote biopsied, and harvested polar bears were used to validate adipose lipid content as a CI via tests of accuracy, precision, sensitivity, biopsy depth, and storage conditions and comparisons to established CIs, to measures of health and to demographic and ecological parameters. The lipid content analyses of even very small biopsy samples were highly accurate and precise, but results were influenced by tissue depth at which the sample was taken. Lipid content of capture biopsies and samples from harvested adult females was correlated with established CIs and/or conformed to expected biological variation and ecological changes. However, lipid content of remote biopsies was lower than capture biopsies and harvested samples, possibly due to lipid loss during dart retrieval. Lipid content CI is a biologically relevant, relatively inexpensive and rapidly assessed CI and can be determined routinely for individuals and populations in order to infer large-scale spatial and long-term temporal trends. As it is possible to collect samples during routine harvesting or remotely using biopsy darts, monitoring and assessment of body condition can be accomplished without capture and handling procedures or noninvasively, which are methods that are preferred by local communities. However, further work is needed to apply the method to remote biopsies.

  8. Brain region-specific perfluoroalkylated sulfonate (PFSA) and carboxylic acid (PFCA) accumulation and neurochemical biomarker responses in east Greenland polar bears (Ursus maritimus).

    Science.gov (United States)

    Eggers Pedersen, Kathrine; Basu, Niladri; Letcher, Robert; Greaves, Alana K; Sonne, Christian; Dietz, Rune; Styrishave, Bjarne

    2015-04-01

    Perfluoroalkyl substances (PFASs) is a growing class of contaminants in the Arctic environment, and include the established perfluorinated sulfonates (PFSAs; especially perfluorooctane sulfonate (PFOS)) and carboxylic acids (PFCAs). PFSAs and PFCAs of varying chain length have been reported to bioaccumulate in lipid rich tissues of the brain among other tissues such as liver, and can reach high concentrations in top predators including the polar bear. PFCA and PFSA bioaccummulation in the brain has the potential to pose neurotoxic effects and therefore we conducted a study to investigate if variations in neurochemical transmitter systems i.e. the cholinergic, glutaminergic, dopaminergic and GABAergic, could be related to brain-specific bioaccumulation of PFASs in East Greenland polar bears. Nine brain regions from nine polar bears were analyzed for enzyme activity (monoamine oxidase (MAO), acetylcholinesterase (AChE) and glutamine synthetase (GS)) and receptor density (dopamine-2 (D2), muscarinic cholinergic (mAChR) and gamma-butyric acid type A (GABA-A)) along with PFSA and PFCA concentrations. Average brain ∑PFSA concentration was 25ng/g ww where PFOS accounted for 91%. Average ∑PFCA concentration was 88ng/g ww where PFUnDA, PFDoDA and PFTrDA combined accounted for 79%. The highest concentrations of PFASs were measured in brain stem, cerebellum and hippocampus. Correlative analyses were performed both across and within brain regions. Significant positive correlations were found between PFASs and MAO activity in occipital lobe (e.g. ∑PFCA; rp=0.83, p=0.041, n=6) and across brain regions (e.g. ∑PFCA; rp=0.47, p=0.001, ∑PFSA; rp=0.44, p>0.001; n=50). GABA-A receptor density was positively correlated with two PFASs across brain regions (PFOS; rp=0.33, p=0.02 and PFDoDA; rp=0.34, p=0.014; n=52). Significant negative correlations were found between mAChR density and PFASs in cerebellum (e.g. ∑PFCA; rp=-0.95, p=0.013, n=5) and across brain regions (e.g.

  9. An immunohistochemical study of retinol-binding protein (RBP) in livers of free-living polar bears (Ursus maritimus) from east Greenland.

    Science.gov (United States)

    Heier, Annabelle; Sonne, Christian; Gröne, Andrea; Leifsson, Pall S; Dietz, Rune; Born, Erik W; Bacciarini, Luca N

    2005-09-01

    From 1999 to 2002 samples from 114 free-ranging polar bears (Ursus maritimus) were collected in the municipality of Scoresby Sound, East Greenland, to detect levels of organochlorines and potential histopathologic changes. Livers of 16 female polar bears from this group were evaluated histologically and analyzed for hepatic retinol-binding protein by immunohistochemistry. Retinol-binding protein is the main transport protein for retinol, an important vitamin A metabolite in the polar bear. Only mild pathologic changes were noted on histologic evaluation of the livers. Small lymphocytic or lymphohistiocytic infiltrates were present in all the livers. Small lipid granulomas, mild periportal fibrosis, and bile duct proliferation were found in several cases. Immunohistochemistry for retinol-binding protein of hepatic tissue from free-ranging polar bears showed no distinct difference in staining intensity by a number of criteria: age, season (fasting and nonfasting), or lactation status. The staining was diffuse to finely stippled in the cytoplasm and showed very little variation among the animals. Because of the lack of macroscopic changes and the absence of severe histologic liver lesions, these polar bears were assumed to be healthy. The diffuse cytoplasmic retinol-binding protein staining in hepatocytes of free-ranging polar bears varies markedly from the prominent granular, less intense staining of captive polar bears investigated previously.

  10. Effects of capturing and collaring on polar bears: findings from long-term research on the southern Beaufort Sea population

    Science.gov (United States)

    Rode, Karyn D.; Pagano, Anthony M.; Bromaghin, Jeffrey F.; Atwood, Todd C.; Durner, George M.; Simac, Kristin S.; Amstrup, Steven C.

    2014-01-01

    Context: The potential for research methods to affect wildlife is an increasing concern among both scientists and the public. This topic has a particular urgency for polar bears because additional research is needed to monitor and understand population responses to rapid loss of sea ice habitat.Aims: This study used data collected from polar bears sampled in the Alaska portion of the southern Beaufort Sea to investigate the potential for capture to adversely affect behaviour and vital rates. We evaluated the extent to which capture, collaring and handling may influence activity and movement days to weeks post-capture, and body mass, body condition, reproduction and survival over 6 months or more.Methods: We compared post-capture activity and movement rates, and relationships between prior capture history and body mass, body condition and reproductive success. We also summarised data on capture-related mortality.Key results: Individual-based estimates of activity and movement rates reached near-normal levels within 2–3 days and fully normal levels within 5 days post-capture. Models of activity and movement rates among all bears had poor fit, but suggested potential for prolonged, lower-level rate reductions. Repeated captures was not related to negative effects on body condition, reproduction or cub growth or survival. Capture-related mortality was substantially reduced after 1986, when immobilisation drugs were changed, with only 3 mortalities in 2517 captures from 1987–2013.Conclusions: Polar bears in the southern Beaufort Sea exhibited the greatest reductions in activity and movement rates 3.5 days post-capture. These shorter-term, post-capture effects do not appear to have translated into any long-term effects on body condition, reproduction, or cub survival. Additionally, collaring had no effect on polar bear recovery rates, body condition, reproduction or cub survival.Implications: This study provides empirical evidence that current capture

  11. Identifying and managing an adverse food reaction in a polar bear (Ursus maritimus) by an elimination diet trial.

    Science.gov (United States)

    Monson, Sara; Minter, Larry J; Krouse, Marissa; De Voe, Ryan S

    2014-06-01

    A 16-yr-old polar bear (Ursus maritimus) presented with severe diarrhea shortly following transfer to the North Carolina Zoological Park. Multiple diagnostic procedures were performed over several months and the cause of the chronic diarrhea was inconclusive. Histologically, colonic mucosal biopsies were consistent with severe chronic eosinophilic and lymphoplasmacytic colitis with no evidence of etiologic agents present. A dietary elimination trial was conducted and an adverse food reaction to the dog chow in the diet was confirmed.

  12. Flame retardants and legacy contaminants in polar bears from Alaska, Canada, East Greenland and Svalbard, 2005-2008.

    Science.gov (United States)

    McKinney, Melissa A; Letcher, Robert J; Aars, Jon; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; Gabrielsen, Geir W; Peacock, Elizabeth; Sonne, Christian

    2011-02-01

    Flame retardants and legacy contaminants were analyzed in adipose tissue from 11 circumpolar polar bear (Ursus maritimus) subpopulations in 2005-2008 spanning Alaska east to Svalbard. Although 37 polybrominated diphenyl ethers (PBDEs), total-(α)-hexabromocyclododecane (HBCD), 2 polybrominated biphenyls (PBBs), pentabromotoluene, pentabromoethylbenzene, hexabromobenzene, 1,2-bis(2,4,6-tribromophenoxy(ethane) and decabromodiphenyl ethane were screened, only 4 PBDEs, total-(α-)HBCD and BB153 were consistently found. Geometric mean ΣPBDE (4.6-78.4 ng/g lipid weight (lw)) and BB153 (2.5-81.1 ng/g lw) levels were highest in East Greenland (43.2 and 39.2 ng/g lipid weight (lw), respectively), Svalbard (44.4 and 20.9 ng/g lw) and western (38.6 and 30.1 ng/g lw) and southern Hudson Bay (78.4 and 81.1 ng/g lw). Total-(α)-HBCD levels (polar bear studies, ΣPBDE, total-(α)-HBCD, p,p'-DDE and ΣCHL levels consistently declined, whereas levels of other legacy contaminants did not. International regulations have clearly been effective in reducing levels of several legacy contaminants in polar bears relative to historical levels. However, slow or stalling declines of certain historic pollutants like PCBs and a complex mixture of "new" chemicals continue to be of concern to polar bear health and that of their arctic marine ecosystems. Copyright © 2010 Elsevier Ltd. All rights reserved.

  13. Are liver and renal lesions in East Greenland polar bears (Ursus maritimus associated with high mercury levels?

    Directory of Open Access Journals (Sweden)

    Born Erik W

    2007-04-01

    Full Text Available Abstract Background In the Arctic, polar bears (Ursus maritimus bio-accumulate mercury as they prey on polluted ringed seals (Phoca hispida and bearded seals (Erignathus barbatus. Studies have shown that polar bears from East Greenland are among the most mercury polluted species in the Arctic. It is unknown whether these levels are toxic to liver and kidney tissue. Methods We investigated the histopathological impact from anthropogenic long-range transported mercury on East Greenland polar bear liver (n = 59 and kidney (n = 57 tissues. Results Liver mercury levels ranged from 1.1–35.6 μg/g wet weight and renal levels ranged from 1–50 μg/g wet weight, of which 2 liver values and 9 kidney values were above known toxic threshold level of 30 μg/g wet weight in terrestrial mammals. Evaluated from age-correcting ANCOVA analyses, liver mercury levels were significantly higher in individuals with visible Ito cells (p Conclusion Based on these relationships and the nature of the chronic inflammation we conclude that the lesions were likely a result of recurrent infections and ageing but that long-term exposure to mercury could not be excluded as a co-factor. The information is important as it is likely that tropospheric mercury depletion events will continue to increase the concentrations of this toxic heavy metal in the Sub Arctic and Arctic marine food webs.

  14. Patterns of faunal extinction and paleoclimatic change from mid-Holocene mammoth and polar bear remains, Pribilof Islands, Alaska

    Science.gov (United States)

    Veltre, Douglas W.; Yesner, David R.; Crossen, Kristine J.; Graham, Russell W.; Coltrain, Joan B.

    2008-07-01

    Qagnaxˆ Cave, a lava tube cave on St. Paul Island in the Pribilofs, has recently produced a mid-Holocene vertebrate faunal assemblage including woolly mammoth, polar bear, caribou, and Arctic fox. Several dates on the mammoth remains converge on 5700 14C yr BP. These dates, ~ 2300 yr younger than mammoth dates previously published from the Pribilof Islands, make these the youngest remains of proboscideans, and of non-extinct Quaternary megafauna, recovered from North America. Persistence of mammoths on the Pribilofs is most parsimoniously explained by the isolation of the Pribilofs and the lack of human presence in pre-Russian contact times, but an additional factor may have been the local existence of high-quality forage in the form of grasses enriched by nutrients derived from local Holocene tephras. This interpretation is reinforced by stable carbon and nitrogen isotope values obtained from the mammoth remains. The endpoint of mammoth survival in the Pribilofs is unknown, but maybe coterminous with the arrival of polar bears whose remains in the cave date to the Neoglacial cold period of ~ 4500 to 3500 14C yr BP. The polar bear record corroborates a widespread cooling of the Bering Sea region at that time.

  15. Tissue-specific congener composition of organohalogen and metabolite contaminants in East Greenland polar bears (Ursus maritimus)

    Energy Technology Data Exchange (ETDEWEB)

    Gebbink, Wouter A. [National Wildlife Research Centre, Science and Technology Branch, Environment Canada, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Sonne, Christian; Dietz, Rune; Kirkegaard, Maja; Riget, Frank F. [Department of Arctic Environment, National Environmental Research Institute, University of Aarhus, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Born, Erik W. [Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland (Denmark); Muir, Derek C.G. [Water Science and Technology Directorate, Environment Canada, Burlington, Ontario L7R 4A6 (Canada); Letcher, Robert J. [National Wildlife Research Centre, Science and Technology Branch, Environment Canada, Carleton University, Ottawa, Ontario K1S 5B6 (Canada); Department of Chemistry, Carleton University, Ottawa, Ontario K1S 5B6 (Canada)], E-mail: robert.letcher@ec.gc.ca

    2008-04-15

    Congener patterns of the major organohalogen contaminant classes of PCBs, PBDEs and their metabolites and/or by-products (OH-PCBs, MeSO{sub 2}-PCBs, OH-PBDEs and MeO-PBDEs) were examined in adipose tissue, liver, brain and blood of East Greenland polar bears (Ursus maritimus). PCB, OH-PCB, MeSO{sub 2}-PCB and PBDE congener patterns showed significant differences (p {<=} 0.05) mainly in the liver and the brain relative to the adipose tissue and the blood. OH-PBDEs and MeO-PBDEs were not detected in the brain and liver, but had different patterns in blood versus the adipose tissue. Novel OH-polybrominated biphenyls (OH-PBBs), one tri- and two tetra-brominated OH-PBBs were detected in all tissues and blood. Congener pattern differences among tissues and blood are likely due to a combination of factors, e.g., biotransformation and retention in the liver, retention in the blood and blood-brain barrier transport. Our findings suggest that different congener pattern exposures to these classes of contaminants should be considered with respect to potential target tissue-specific effects in East Greenland polar bears. - Tissues-specific (adipose tissue, liver, brain and blood) differences exist for the congener patterns of PCBs, PBDEs and their metabolites/degradation products in East Greenland polar bears.

  16. Three decades (1983-2010) of contaminant trends in East Greenland polar bears (Ursus maritimus). Part 2: brominated flame retardants.

    Science.gov (United States)

    Dietz, Rune; Rigét, Frank F; Sonne, Christian; Born, Erik W; Bechshøft, Thea; McKinney, Melissa A; Drimmie, Robert J; Muir, Derek C G; Letcher, Robert J

    2013-09-01

    Brominated flame retardants were determined in adipose tissues from 294 polar bears (Ursus maritimus) sampled in East Greenland in 23 of the 28years between 1983 and 2010. Significant linear increases were found for sum polybrominated diphenyl ether (ΣPBDE), BDE100, BDE153, and hexabromocyclododecane (HBCD). Average increases of 5.0% per year (range: 2.9-7.6%/year) were found for the subadult polar bears. BDE47 and BDE99 concentrations did not show a significant linear trend over time, but rather a significant non-linear trend peaking between 2000 and 2004. The average ΣPBDE concentrations increased 2.3 fold from 25.0ng/g lw (95% C.I.: 15.3-34.7ng/g lw) in 1983-1986 to 58.5ng/g lw (95% C.I.: 43.6-73.4ng/g lw) in 2006-2010. Similar but fewer statistically significant trends were found for adult females and adult males likely due to smaller sample size and years. Analyses of δ(15)N and δ(13)C stable isotopes in hair revealed no clear linear temporal trends in trophic level or carbon source, respectively, and non-linear trends differed among sex and age groups. These increasing concentrations of organobromine contaminants contribute to complex organohalogen mixture, already causing health effects to the East Greenland polar bears. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Tissue-specific congener composition of organohalogen and metabolite contaminants in East Greenland polar bears (Ursus maritimus)

    International Nuclear Information System (INIS)

    Gebbink, Wouter A.; Sonne, Christian; Dietz, Rune; Kirkegaard, Maja; Riget, Frank F.; Born, Erik W.; Muir, Derek C.G.; Letcher, Robert J.

    2008-01-01

    Congener patterns of the major organohalogen contaminant classes of PCBs, PBDEs and their metabolites and/or by-products (OH-PCBs, MeSO 2 -PCBs, OH-PBDEs and MeO-PBDEs) were examined in adipose tissue, liver, brain and blood of East Greenland polar bears (Ursus maritimus). PCB, OH-PCB, MeSO 2 -PCB and PBDE congener patterns showed significant differences (p ≤ 0.05) mainly in the liver and the brain relative to the adipose tissue and the blood. OH-PBDEs and MeO-PBDEs were not detected in the brain and liver, but had different patterns in blood versus the adipose tissue. Novel OH-polybrominated biphenyls (OH-PBBs), one tri- and two tetra-brominated OH-PBBs were detected in all tissues and blood. Congener pattern differences among tissues and blood are likely due to a combination of factors, e.g., biotransformation and retention in the liver, retention in the blood and blood-brain barrier transport. Our findings suggest that different congener pattern exposures to these classes of contaminants should be considered with respect to potential target tissue-specific effects in East Greenland polar bears. - Tissues-specific (adipose tissue, liver, brain and blood) differences exist for the congener patterns of PCBs, PBDEs and their metabolites/degradation products in East Greenland polar bears

  18. Effects of Polar Bear and Killer Whale Derived Contaminant Cocktails on Marine Mammal Immunity.

    Science.gov (United States)

    Desforges, Jean-Pierre; Levin, Milton; Jasperse, Lindsay; De Guise, Sylvain; Eulaers, Igor; Letcher, Robert J; Acquarone, Mario; Nordøy, Erling; Folkow, Lars P; Hammer Jensen, Trine; Grøndahl, Carsten; Bertelsen, Mads F; St Leger, Judy; Almunia, Javier; Sonne, Christian; Dietz, Rune

    2017-10-03

    Most controlled toxicity studies use single chemical exposures that do not represent the real world situation of complex mixtures of known and unknown natural and anthropogenic substances. In the present study, complex contaminant cocktails derived from the blubber of polar bears (PB; Ursus maritimus) and killer whales (KW; Orcinus orca) were used for in vitro concentration-response experiments with PB, cetacean and seal spp. immune cells to evaluate the effect of realistic contaminant mixtures on various immune functions. Cytotoxic effects of the PB cocktail occurred at lower concentrations than the KW cocktail (1 vs 16 μg/mL), likely due to differences in contaminant profiles in the mixtures derived from the adipose of each species. Similarly, significant reduction of lymphocyte proliferation occurred at much lower exposures in the PB cocktail (EC 50 : 0.94 vs 6.06 μg/mL; P < 0.01), whereas the KW cocktail caused a much faster decline in proliferation (slope: 2.9 vs 1.7; P = 0.04). Only the KW cocktail modulated natural killer (NK) cell activity and neutrophil and monocyte phagocytosis in a concentration- and species-dependent manner. No clear sensitivity differences emerged when comparing cetaceans, seals and PB. Our results showing lower effect levels for complex mixtures relative to single compounds suggest that previous risk assessments underestimate the effects of real world contaminant exposure on immunity. Our results using blubber-derived contaminant cocktails add realism to in vitro exposure experiments and confirm the immunotoxic risk marine mammals face from exposure to complex mixtures of environmental contaminants.

  19. Modeling optical and UV polarization of AGNs. III. From uniform-density to clumpy regions

    Science.gov (United States)

    Marin, F.; Goosmann, R. W.; Gaskell, C. M.

    2015-05-01

    Context. A growing body of evidence suggests that some, if not all, scattering regions of active galactic nuclei (AGNs) are clumpy. The inner AGN components cannot be spatially resolved with current instruments and must be studied by numerical simulations of observed spectroscopy and polarization data. Aims: We run radiative transfer models in the optical/UV for a variety of AGN reprocessing regions with different distributions of clumpy scattering media. We obtain geometry-sensitive polarization spectra and images to improve our previous AGN models and their comparison with the observations. Methods: We use the latest public version 1.2 of the Monte Carlo code stokes presented in the first two papers of this series to model AGN reprocessing regions of increasing morphological complexity. We replace previously uniform-density media with up to thousands of constant-density clumps. We couple a continuum source to fragmented equatorial scattering regions, polar outflows, and toroidal obscuring dust regions and investigate a wide range of geometries. We also consider different levels of fragmentation in each scattering region to evaluate the importance of fragmentation for the net polarization of the AGN. Results: In comparison with uniform-density models, equatorial distributions of gas and dust clouds result in grayer spectra and show a decrease in the net polarization percentage at all lines of sight. The resulting polarization position angle depends on the morphology of the clumpy structure, with extended tori favoring parallel polarization while compact tori produce orthogonal polarization position angles. In the case of polar scattering regions, fragmentation increases the net polarization unless the cloud filling factor is small. A complete AGN model constructed from the individual, fragmented regions can produce low polarization percentages (<2%), with a parallel polarization angle for observer inclinations up to 70° for a torus half opening angle of 60°. For

  20. Solvent density mode instability in non-polar solutions

    Indian Academy of Sciences (India)

    this region produces time scales, one in the range of 1–2 ps and the other in the range of ≥10 ps for f = 4 as reported earlier [17]. Note also that both the values of f (f = 4) and density for which these two time scales are predicted are very close to the solute–solvent systems for which the experiments have reported multiple ...

  1. Performance and retention of lightweight satellite radio tags applied to the ears of polar bears (Ursus maritimus)

    Science.gov (United States)

    Wiig, Øystein; Born, Erik W.; Laidre, Kristin L.; Dietz, Rune; Jensen, Mikkel Villum; Durner, George M.; Pagano, Anthony M.; Regehr, Eric V.; St. Martin, Michelle; Atkinson, Stephen N.; Dyck, Markus

    2017-01-01

    BackgroundSatellite telemetry studies provide information that is critical to the conservation and management of species affected by ecological change. Here we report on the performance and retention of two types (SPOT-227 and SPOT-305A) of ear-mounted Argos-linked satellite transmitters (i.e., platform transmitter terminal, or PTT) deployed on free-ranging polar bears in Eastern Greenland, Baffin Bay, Kane Basin, the southern Beaufort Sea, and the Chukchi Sea during 2007–2013.ResultsTransmissions from 142 out of 145 PTTs deployed on polar bears were received for an average of 69.3 days. The average functional longevity, defined as the number of days they transmitted while still attached to polar bears, for SPOT-227 was 56.8 days and for SPOT-305A was 48.6 days. Thirty-four of the 142 (24%) PTTs showed signs of being detached before they stopped transmitting, indicating that tag loss was an important aspect of tag failure. Furthermore, 10 of 26 (38%) bears that were re-observed following application of a PTT had a split ear pinna, suggesting that some transmitters were detached by force. All six PTTs that were still on bears upon recapture had lost the antenna, which indicates that antenna breakage was a significant contributor to PTT failure. Finally, only nine of the 142 (6%) PTTs—three of which were still attached to bears—had a final voltage reading close to the value indicating battery exhaustion. This suggests that battery exhaustion was not a major factor in tag performance.ConclusionsThe average functional longevity of approximately 2 months for ear-mounted PTTs (this study) is poor compared to PTT collars fitted to adult female polar bears, which can last for several years. Early failure of the ear-mounted PTTs appeared to be caused primarily by detachment from the ear or antenna breakage. We suggest that much smaller and lighter ear-mounted transmitters are necessary to reduce the risk of tissue irritation, tissue damage, and tag detachment, and

  2. Exposure to mixtures of organohalogen contaminants and associative interactions with thyroid hormones in East Greenland polar bears (Ursus maritimus).

    Science.gov (United States)

    Villanger, Gro D; Jenssen, Bjørn M; Fjeldberg, Rita R; Letcher, Robert J; Muir, Derek C G; Kirkegaard, Maja; Sonne, Christian; Dietz, Rune

    2011-05-01

    We investigated the multivariate relationships between adipose tissue residue levels of 48 individual organohalogen contaminants (OHCs) and circulating thyroid hormone (TH) levels in polar bears (Ursus maritimus) from East Greenland (1999-2001, n=62), using projection to latent structure (PLS) regression for four groupings of polar bears; subadults (SubA), adult females with cubs (AdF_N), adult females without cubs (AdF_S) and adult males (AdM). In the resulting significant PLS models for SubA, AdF_N and AdF_S, some OHCs were especially important in explaining variations in circulating TH levels: polybrominated diphenylether (PBDE)-99, PBDE-100, PBDE-153, polychlorinated biphenyl (PCB)-52, PCB-118, cis-nonachlor, trans-nonachlor, trichlorobenzene (TCB) and pentachlorobenzene (QCB), and both negative and positive relationships with THs were found. In addition, the models revealed that DDTs had a positive influence on total 3,5,3'-triiodothyronine (TT3) in AdF_S, and that a group of 17 higher chlorinated ortho-PCBs had a positive influence on total 3,5,3',5'-tetraiodothyronine (thyroxine, TT4) in AdF_N. TH levels in AdM seemed less influenced by OHCs because of non-significant PLS models. TH levels were also influenced by biological factors such as age, sex, body size, lipid content of adipose tissue and sampling date. When controlling for biological variables, the major relationships from the PLS models for SubA, AdF_N and AdF_S were found significant in partial correlations. The most important OHCs that influenced TH levels in the significant PLS models may potentially act through similar mechanisms on the hypothalamic-pituitary-thyroid (HPT) axis, suggesting that both combined effects by dose and response addition and perhaps synergistic potentiation may be a possibility in these polar bears. Statistical associations are not evidence per se of biological cause-effect relationships. Still, the results of the present study indicate that OHCs may affect circulating

  3. In vitro assay shows that PCB metabolites completely saturate thyroid hormone transport capacity in blood of wild polar bears (Ursus maritimus)

    NARCIS (Netherlands)

    Gutleb, A.C.; Cenijn, P.H.; van Velzen, P.; Lie, E.; Ropstad, E.; Skaare, J.U.; Malmberg, T.; Bergman, A.; Gabrielsen, G. W.; Legler, J.

    2010-01-01

    Persistent chemicals accumulate in the arctic environment due to their chemical reactivity and physicochemical properties and polychlorinated biphenyls (PCBs) are the most concentrated pollutant class in polar bears (Ursus maritimus). Metabolism of PCB and polybrominated biphenyl ether (PBDE)

  4. Nuclear reactivity indices in the context of spin polarized density functional theory

    International Nuclear Information System (INIS)

    Cardenas, Carlos; Lamsabhi, Al Mokhtar; Fuentealba, Patricio

    2006-01-01

    In this work, the nuclear reactivity indices of density functional theory have been generalized to the spin polarized case and their relationship to electron spin polarized indices has been established. In particular, the spin polarized version of the nuclear Fukui function has been proposed and a finite difference approximation has been used to evaluate it. Applications to a series of triatomic molecules demonstrate the ability of the new functions to predict the geometrical changes due to a change in the spin multiplicity. The main equations in the different ensembles have also been presented

  5. Effects of polarity, hydrophobicity, and density of ionic liquids on cellulose solubility.

    Science.gov (United States)

    Abe, Mitsuru; Kuroda, Kosuke; Sato, Daiki; Kunimura, Haruhito; Ohno, Hiroyuki

    2015-12-28

    We have synthesised novel ionic liquids (ILs) to show both cellulose dissolution ability and LCST-type phase transition after mixing with water. To realise both polar and hydrophobic properties, tetraalkylphosphonium cations and a series of carboxylate anions were employed to assume hydrophobic and highly polar properties, respectively. Effects of their alkyl chain length on the water compatibility and cellulose solubility of the corresponding ILs were systematically examined. We succeeded in synthesising novel ILs which dissolve cellulose and separable with water at moderate temperature. Through the present study, we have clarified that not only polarity but also density of ILs is an important factor in designing the ILs for cellulose dissolution.

  6. The Energetic Value of Land-Based Foods in Western Hudson Bay and Their Potential to Alleviate Energy Deficits of Starving Adult Male Polar Bears.

    Science.gov (United States)

    Gormezano, Linda J; Rockwell, Robert F

    2015-01-01

    Climate change is predicted to expand the ice-free season in western Hudson Bay and when it grows to 180 days, 28-48% of adult male polar bears are projected to starve unless nutritional deficits can be offset by foods consumed on land. We updated a dynamic energy budget model developed by Molnar et al. to allow influx of additional energy from novel terrestrial foods (lesser snow geese, eggs, caribou) that polar bears currently consume as part of a mixed diet while on land. We calculated the units of each prey, alone and in combination, needed to alleviate these lethal energy deficits under conditions of resting or limited movement (2 km d-1) prior to starvation. We further considered the total energy available from each sex and age class of each animal prey over the period they would overlap land-bound polar bears and calculated the maximum number of starving adult males that could be sustained on each food during the ice-free season. Our results suggest that the net energy from land-based food, after subtracting costs of limited movement to obtain it, could eliminate all projected nutritional deficits of starving adult male polar bears and likely other demographic groups as well. The hunting tactics employed, success rates as well as behavior and abundance of each prey will determine the realized energetic values for individual polar bears. Although climate change may cause a phenological mismatch between polar bears and their historical ice-based prey, it may simultaneously yield a new match with certain land-based foods. If polar bears can transition their foraging behavior to effectively exploit these resources, predictions for starvation-related mortality may be overestimated for western Hudson Bay. We also discuss potential complications with stable-carbon isotope studies to evaluate utilization of land-based foods by polar bears including metabolic effects of capture-related stress and consuming a mixed diet.

  7. The Energetic Value of Land-Based Foods in Western Hudson Bay and Their Potential to Alleviate Energy Deficits of Starving Adult Male Polar Bears.

    Directory of Open Access Journals (Sweden)

    Linda J Gormezano

    Full Text Available Climate change is predicted to expand the ice-free season in western Hudson Bay and when it grows to 180 days, 28-48% of adult male polar bears are projected to starve unless nutritional deficits can be offset by foods consumed on land. We updated a dynamic energy budget model developed by Molnar et al. to allow influx of additional energy from novel terrestrial foods (lesser snow geese, eggs, caribou that polar bears currently consume as part of a mixed diet while on land. We calculated the units of each prey, alone and in combination, needed to alleviate these lethal energy deficits under conditions of resting or limited movement (2 km d-1 prior to starvation. We further considered the total energy available from each sex and age class of each animal prey over the period they would overlap land-bound polar bears and calculated the maximum number of starving adult males that could be sustained on each food during the ice-free season. Our results suggest that the net energy from land-based food, after subtracting costs of limited movement to obtain it, could eliminate all projected nutritional deficits of starving adult male polar bears and likely other demographic groups as well. The hunting tactics employed, success rates as well as behavior and abundance of each prey will determine the realized energetic values for individual polar bears. Although climate change may cause a phenological mismatch between polar bears and their historical ice-based prey, it may simultaneously yield a new match with certain land-based foods. If polar bears can transition their foraging behavior to effectively exploit these resources, predictions for starvation-related mortality may be overestimated for western Hudson Bay. We also discuss potential complications with stable-carbon isotope studies to evaluate utilization of land-based foods by polar bears including metabolic effects of capture-related stress and consuming a mixed diet.

  8. Large plasma density enhancements occurring in the northern polar region during the 6 April 2000 superstorm

    Science.gov (United States)

    Horvath, Ildiko; Lovell, Brian C.

    2014-06-01

    We focus on the ionospheric response of northern high-latitude region to the 6 April 2000 superstorm and aim to investigate how the storm-enhanced density (SED) plume plasma became distributed in the regions of auroral zone and polar cap plus to study the resultant ionospheric features and their development. Multi-instrument observational results combined with model-generated, two-cell convection maps permitted identifying the high-density plasma's origin and the underlying plasma transportation processes. Results show the plasma density feature of polar cap enhancement (PCE; 600 × 103 i+/cm3) appearing for 7 h during the main phase and characterized by increases reaching up to 6 times of the quiet time values. Meanwhile, strong westward convections ( 17,500 m/s) created low plasma densities in a wider region of the dusk cell. Oppositely, small ( 750 m/s) but rigorous westward drifts drove the SED plume plasma through the auroral zone, wherein plasma densities doubled. As the SED plume plasma traveled along the convection streamlines and entered the polar cap, a continuous enhancement of the tongue of ionization (TOI) developed under steady convection conditions. However, convection changes caused slow convections and flow stagnations and thus segmented the TOI feature by locally depleting the plasma in the affected regions of the auroral zone and polar cap. From the strong correspondence of polar cap potential drop and subauroral polarization stream (SAPS), we conclude that the SAPS E-field strength remained strong, and under its prolonged influence, the SED plume provided a continuous supply of downward flowing high-density plasma for the development and maintenance of PCEs.

  9. Whitebark pine, population density, and home-range size of grizzly bears in the greater yellowstone ecosystem.

    Directory of Open Access Journals (Sweden)

    Daniel D Bjornlie

    Full Text Available Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos in the Greater Yellowstone Ecosystem (GYE, recent decline of whitebark pine (WBP; Pinus albicaulis, an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

  10. Whitebark pine, population density, and home-range size of grizzly bears in the greater yellowstone ecosystem.

    Science.gov (United States)

    Bjornlie, Daniel D; Van Manen, Frank T; Ebinger, Michael R; Haroldson, Mark A; Thompson, Daniel J; Costello, Cecily M

    2014-01-01

    Changes in life history traits of species can be an important indicator of potential factors influencing populations. For grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE), recent decline of whitebark pine (WBP; Pinus albicaulis), an important fall food resource, has been paired with a slowing of population growth following two decades of robust population increase. These observations have raised questions whether resource decline or density-dependent processes may be associated with changes in population growth. Distinguishing these effects based on changes in demographic rates can be difficult. However, unlike the parallel demographic responses expected from both decreasing food availability and increasing population density, we hypothesized opposing behavioral responses of grizzly bears with regard to changes in home-range size. We used the dynamic changes in food resources and population density of grizzly bears as a natural experiment to examine hypotheses regarding these potentially competing influences on grizzly bear home-range size. We found that home-range size did not increase during the period of whitebark pine decline and was not related to proportion of whitebark pine in home ranges. However, female home-range size was negatively associated with an index of population density. Our data indicate that home-range size of grizzly bears in the GYE is not associated with availability of WBP, and, for female grizzly bears, increasing population density may constrain home-range size.

  11. Remote identification of potential polar bear maternal denning habitat in northern Alaska using airborne LiDAR

    Science.gov (United States)

    Jones, B. M.; Durner, G. M.; Stoker, J.; Shideler, R.; Perham, C.; Liston, G. E.

    2013-12-01

    Polar bear (Ursus maritimus) populations throughout the Arctic are being threatened by reductions in critical sea ice habitat. Throughout much of their range, polar bears give birth to their young in winter dens that are excavated in snowdrifts. New-born cubs, which are unable to survive exposure to Arctic winter weather, require 2-3 months of the relatively warm, stable, and undisturbed environment of the den for their growth. In the southern Beaufort Sea (BS), polar bears may den on the Alaskan Arctic Coastal Plain (ACP).The proportion of dens occurring on land has increased because of reductions in stable multi-year ice, increases in unconsolidated ice, and lengthening of the fall open-water period. Large portions of the ACP are currently being used for oil and gas activities and proposed projects will likely expand this footprint in the near future. Since petroleum exploration and development activities increase during winter there is the potential for human activities to disturb polar bears in maternal dens. Thus, maps showing the potential distribution of terrestrial denning habitat can help to mitigate negative interactions. Prior remote sensing efforts have consisted of manual interpretation of vertical aerial photography and automated classification of Interferometric Synthetic Aperture (IfSAR) derived digital terrain models (DTM) (5-m spatial resolution) focused on the identification of snowdrift forming landscape features. In this study, we assess the feasibility of airborne Light Detection and Ranging (LiDAR) data (2-m spatial resolution) for the automated classification of potential polar bear maternal denning habitat in a 1,400 km2 area on the central portion of the ACP. The study region spans the BS coast from the Prudhoe Bay oilfield in the west to near Point Thompson in the east and extends inland from 10 to 30 km. Approximately 800 km2 of the study area contains 19 known den locations, 51 field survey sites with information on bank height and

  12. Are liver and renal lesions in East Greenland polar bears (Ursus maritimus) associated with high mercury levels?

    Science.gov (United States)

    Sonne, Christian; Dietz, Rune; Leifsson, Pall S; Asmund, Gert; Born, Erik W; Kirkegaard, Maja

    2007-04-17

    In the Arctic, polar bears (Ursus maritimus) bio-accumulate mercury as they prey on polluted ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). Studies have shown that polar bears from East Greenland are among the most mercury polluted species in the Arctic. It is unknown whether these levels are toxic to liver and kidney tissue. We investigated the histopathological impact from anthropogenic long-range transported mercury on East Greenland polar bear liver (n = 59) and kidney (n = 57) tissues. Liver mercury levels ranged from 1.1-35.6 microg/g wet weight and renal levels ranged from 1-50 microg/g wet weight, of which 2 liver values and 9 kidney values were above known toxic threshold level of 30 microg/g wet weight in terrestrial mammals. Evaluated from age-correcting ANCOVA analyses, liver mercury levels were significantly higher in individuals with visible Ito cells (p < 0.02) and a similar trend was found for lipid granulomas (p = 0.07). Liver mercury levels were significantly lower in individuals with portal bile duct proliferation/fibrosis (p = 0.007) and a similar trend was found for proximal convoluted tubular hyalinisation in renal tissue (p = 0.07). Based on these relationships and the nature of the chronic inflammation we conclude that the lesions were likely a result of recurrent infections and ageing but that long-term exposure to mercury could not be excluded as a co-factor. The information is important as it is likely that tropospheric mercury depletion events will continue to increase the concentrations of this toxic heavy metal in the Sub Arctic and Arctic marine food webs.

  13. Spin polarization versus color–flavor locking in high-density quark matter

    DEFF Research Database (Denmark)

    Tsue, Yasuhiko; da Providência, João; Providência, Constança

    2015-01-01

    It is shown that spin polarization with respect to each flavor in three-flavor quark matter occurs instead of color–flavor locking at high baryon density by using the Nambu–Jona-Lasinio model with four-point tensor-type interaction. Also, it is indicated that the order of phase transition between...... the color–flavor-locked phase and the spin-polarized phase is the first order by means of second-order perturbation theory.......It is shown that spin polarization with respect to each flavor in three-flavor quark matter occurs instead of color–flavor locking at high baryon density by using the Nambu–Jona-Lasinio model with four-point tensor-type interaction. Also, it is indicated that the order of phase transition between...

  14. Spin density measurement of water-bridged Co-dimer using polarized neutrons

    DEFF Research Database (Denmark)

    Damgaard-Møller, Emil; Overgaard, Jacob; Chilton, Nick

    present an experimentally determined spin density using polarized neutron diffraction in a simple water-bridged cobalt dimer [Co2(H2O)(piv)4(Hpiv)2(py)2] which is known to have a small ferromagnetic coupling between the spin centers. Visualizing the SDD could get us one step further in understanding...

  15. Spin-polarized versus chiral condensate in quark matter at finite temperature and density

    DEFF Research Database (Denmark)

    Matsuoka, Hiroaki; Tsue, Yasuhiko; da Providencia, Joao

    2016-01-01

    It is shown that the spin-polarized condensate appears in quark matter at high baryon density and low temperature due to the tensor-type four-point interaction in the Nambu-Jona-Lasiniotype model as a low-energy effective theory of quantum chromodynamics. It is indicated within this low...

  16. Isospin constraints between three cross sections and two polarization density matrices

    CERN Document Server

    Doncel, M G; Minnaert, P

    1972-01-01

    The authors give the relation which isospin conservation imposes between the three cross sections and two polarization density matrices, for three reactions related by two isospin channels. It is valid for arbitrary spin and for spin correlations. Its application to the most usual cases of spin 1 and /sup 3///sub 2/ is given. (6 refs).

  17. Regional contamination versus regional dietary differences: Understanding geographic variation in brominated and chlorinated contaminant levels in polar bears

    Science.gov (United States)

    McKinney, M.A.; Letcher, R.J.; Aars, Jon; Born, E.W.; Branigan, M.; Dietz, R.; Evans, T.J.; Gabrielsen, G.W.; Muir, D.C.G.; Peacock, E.; Sonne, C.

    2011-01-01

    The relative contribution of regional contamination versus dietary differences to geographic variation in polar bear (Ursus maritimus) contaminant levels is unknown. Dietary variation between Alaska Canada, East Greenland, and Svalbard subpopulations was assessed by muscle nitrogen and carbon stable isotope (?? 15N, ?? 13C) and adipose fatty acid (FA) signatures relative to their main prey (ringed seals). Western and southern Hudson Bay signatures were characterized by depleted ?? 15N and ??13C, lower proportions of C20 and C22 monounsaturated FAs and higher proportions of C18 and longer chain polyunsaturated FAs. East Greenland and Svalbard signatures were reversed relative to Hudson Bay. Alaskan ?? 2011 American Chemical Society.

  18. Evolution of Mars’ Northern Polar Seasonal CO2 deposits: variations in surface brightness and bulk density

    Science.gov (United States)

    Mount, Christopher P.; Titus, Timothy N.

    2015-01-01

    Small scale variations of seasonal ice are explored at different geomorphic units on the Northern Polar Seasonal Cap (NPSC). We use seasonal rock shadow measurements, combined with visible and thermal observations, to calculate density over time. The coupling of volume density and albedo allows us to determine the microphysical state of the seasonal CO2 ice. We find two distinct endmembers across the NPSC: 1) Snow deposits may anneal to form an overlying slab layer that fractures. These low density deposits maintain relatively constant densities over springtime. 2) Porous slab deposits likely anneal rapidly in early spring and fracture in late spring. These high density deposits dramatically increase in density over time. The endmembers appear to be correlated with latitude.

  19. Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic.

    Science.gov (United States)

    Iverson, Samuel A; Gilchrist, H Grant; Smith, Paul A; Gaston, Anthony J; Forbes, Mark R

    2014-03-22

    Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands. In this study, we examined polar bears' use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010-2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator-prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems.

  20. Comparing urban and wildland bear densities with a DNA-based capture-mark-recapture approach

    OpenAIRE

    Fusaro, Jonathan L.; Conner, Mary M.; Conover, Michael R.; Taylor, Timothy J.; Kenyon, Marc W., Jr.; Sherman, Jamie R.; Ernest, Holly B.

    2017-01-01

    California’s black bear (Ursus americanus) population has tripled over the last 3 decades, causing an increased incidence of human–bear conflicts, many of which now occur in urban areas. Consequently, it is imperative that bear managers have the ability to monitor population parameters in both wildland and urban environments to help manage bears. Capture-mark-recapture (CMR) methods using uniquely typed genetic samples (DNA) collected via hair-snares have been widely used to monitor bears in ...

  1. Estimating black bear density in New Mexico using noninvasive genetic sampling coupled with spatially explicit capture-recapture methods

    Science.gov (United States)

    Gould, Matthew J.; Cain, James W.; Roemer, Gary W.; Gould, William R.

    2016-01-01

    During the 2004–2005 to 2015–2016 hunting seasons, the New Mexico Department of Game and Fish (NMDGF) estimated black bear abundance (Ursus americanus) across the state by coupling density estimates with the distribution of primary habitat generated by Costello et al. (2001). These estimates have been used to set harvest limits. For example, a density of 17 bears/100 km2 for the Sangre de Cristo and Sacramento Mountains and 13.2 bears/100 km2 for the Sandia Mountains were used to set harvest levels. The advancement and widespread acceptance of non-invasive sampling and mark-recapture methods, prompted the NMDGF to collaborate with the New Mexico Cooperative Fish and Wildlife Research Unit and New Mexico State University to update their density estimates for black bear populations in select mountain ranges across the state.We established 5 study areas in 3 mountain ranges: the northern (NSC; sampled in 2012) and southern Sangre de Cristo Mountains (SSC; sampled in 2013), the Sandia Mountains (Sandias; sampled in 2014), and the northern (NSacs) and southern Sacramento Mountains (SSacs; both sampled in 2014). We collected hair samples from black bears using two concurrent non-invasive sampling methods, hair traps and bear rubs. We used a gender marker and a suite of microsatellite loci to determine the individual identification of hair samples that were suitable for genetic analysis. We used these data to generate mark-recapture encounter histories for each bear and estimated density in a spatially explicit capture-recapture framework (SECR). We constructed a suite of SECR candidate models using sex, elevation, land cover type, and time to model heterogeneity in detection probability and the spatial scale over which detection probability declines. We used Akaike’s Information Criterion corrected for small sample size (AICc) to rank and select the most supported model from which we estimated density.We set 554 hair traps, 117 bear rubs and collected 4,083 hair

  2. Black bears with longer disuse (hibernation) periods have lower femoral osteon population density and greater mineralization and intracortical porosity.

    Science.gov (United States)

    Wojda, Samantha J; Weyland, David R; Gray, Sarah K; McGee-Lawrence, Meghan E; Drummer, Thomas D; Donahue, Seth W

    2013-08-01

    Intracortical bone remodeling is persistent throughout life, leading to age related increases in osteon population density (OPD). Intracortical porosity also increases with age in many mammals including humans, contributing to bone fragility and fracture risk. Unbalanced bone resorption and formation during disuse (e.g., physical inactivity) also increases intracortical porosity. In contrast, hibernating bears are a naturally occurring model for the prevention of both age-related and disuse osteoporoses. Intracortical bone remodeling is decreased during hibernation, but resorption and formation remain balanced. Black bears spend 0.25-7 months in hibernation annually depending on climate and food availability. We found longer hibernating bears demonstrate lower OPD and higher cortical bone mineralization than bears with shorter hibernation durations, but we surprisingly found longer hibernating bears had higher intracortical porosity. However, bears from three different latitudes showed age-related decreases in intracortical porosity, indicating that regardless of hibernation duration, black bears do not show the disuse- or age-related increases in intracortical porosity which is typical of other animals. This ability to prevent increases in intracortical porosity likely contributes to their ability to maintain bone strength during prolonged periods of physical inactivity and throughout life. Improving our understanding of the unique bone metabolism in hibernating bears will potentially increase our ability to develop treatments for age- and disuse-related osteoporoses in humans. Copyright © 2013 Wiley Periodicals, Inc.

  3. Polar-solvation classical density-functional theory for electrolyte aqueous solutions near a wall

    Science.gov (United States)

    Warshavsky, Vadim; Marucho, Marcelo

    2016-01-01

    A precise description of the structural and dielectric properties of liquid water is critical to understanding the physicochemical properties of solutes in electrolyte solutions. In this article, a mixture of ionic and dipolar hard spheres is considered to account for water crowding and polarization effects on ionic electrical double layers near a uniformly charged hard wall. As a unique feature, solvent hard spheres carrying a dipole at their centers were used to model water molecules at experimentally known concentration, molecule size, and dipolar moment. The equilibrium ionic and dipole density profiles of this electrolyte aqueous model were calculated using a polar-solvation classical density-functional theory (PSCDFT). These profiles were used to calculate the charge density distribution, water polarization, dielectric permittivity function, and mean electric potential profiles as well as differential capacitance, excess adsorptions, and wall-fluid surface tension. These results were compared with those corresponding to the pure dipolar model and unpolar primitive solvent model of electrolyte aqueous solutions to understand the role that water crowding and polarization effects play on the structural and thermodynamic properties of these systems. Overall, PSCDFT predictions are in agreement with available experimental data. PMID:27176352

  4. Metallicity at interphase boundaries due to polar catastrophe induced by charge density discontinuity

    KAUST Repository

    Albar, Arwa

    2018-02-09

    The electronic properties of interphase boundaries are of basic importance for most materials, particularly when those properties deviate strongly from the bulk behavior. We introduce a mechanism that can result in metallicity at stoichiometric interphase boundaries between semiconductors based on the idea of polar catastrophe, which is usually considered only in the context of heterostructures. To this end, we perform ab initio calculations within density functional theory to investigate the electronic states at stoichiometric SnO/SnO2 (110) interphase boundaries. In this system, one would not expect polar catastrophe to have a role according to state-of-the-art theory because the interface lacks formal charge discontinuity. However, we observe the formation of a hole gas between the semiconductors SnO and SnO2. To explain these findings, we provide a generalized theory based on the idea that the charge density discontinuity between SnO and SnO2, a consequence of lattice mismatch, drives a polar catastrophe scenario. As a result, SnO/SnO2 (110) interphase boundaries can develop metallicity depending on the grain size. The concept of metallicity due to polar catastrophe induced by charge density discontinuity is of general validity and applies to many interphase boundaries with lattice mismatch.

  5. Tissue-specific congener composition of organohalogen and metabolite contaminants in East Greenland polar bears (Ursus maritimus).

    Science.gov (United States)

    Gebbink, Wouter A; Sonne, Christian; Dietz, Rune; Kirkegaard, Maja; Riget, Frank F; Born, Erik W; Muir, Derek C G; Letcher, Robert J

    2008-04-01

    Congener patterns of the major organohalogen contaminant classes of PCBs, PBDEs and their metabolites and/or by-products (OH-PCBs, MeSO2-PCBs, OH-PBDEs and MeO-PBDEs) were examined in adipose tissue, liver, brain and blood of East Greenland polar bears (Ursus maritimus). PCB, OH-PCB, MeSO2-PCB and PBDE congener patterns showed significant differences (ppolar bears.

  6. Sea ice-associated diet change increases the levels of chlorinated and brominated contaminants in polar bears.

    Science.gov (United States)

    Mckinney, Melissa A; Peacock, Elizabeth; Letcher, Robert J

    2009-06-15

    Two global environmental issues, climate change and contamination by persistent organic pollutants, represent major concerns for arctic ecosystems. Yet, it is unclear how these two stressors interact in the Arctic. For instance, the influence of climate-associated changes in food web structure on exposure to pollutants within arctic ecosystems is presently unknown. Here, we report on recent changes in feeding ecology (1991-2007) in polar bears (Ursus maritimus) from the western Hudson Bay subpopulation that have resulted in increases in the tissue concentrations of several chlorinated and brominated contaminants. Differences in timing of the annual sea ice breakup explained a significant proportion of the diet variation among years. As expected from climate change predictions, this diet change was consistent with an increase in the consumed proportions of open water-associated seal species compared to ice-associated seal species in years of earlier sea ice breakup. Our results demonstrate that climate change is a modulating influence on contaminants in this polar bear subpopulation and may pose an additional and previously unidentified threat to northern ecosystems through altered exposures to contaminants.

  7. Age and seasonal variability of polybrominated diphenyl ethers in free-ranging East Greenland polar bears (Ursus maritimus)

    International Nuclear Information System (INIS)

    Dietz, Rune; Riget, Frank F.; Sonne, Christian; Letcher, Robert J.; Backus, Sean; Born, Erik W.; Kirkegaard, Maja; Muir, Derek C.G.

    2007-01-01

    Polybrominated diphenyl ethers (PBDEs) were analysed in adipose tissue from 92 East Greenland polar bears (Ursus maritimus) sampled during 1999-2001. Mean ΣPBDE concentrations were 70 ng/g lipid weight (lw) (range: 22-192 ng/g lw) and showed no relationship with age or sex. Of the 32 analysed PBDE congeners; BDE47, BDE153, BDE99 and BDE100 dominated, and comprised 99.6% of the ΣPBDE concentration. The ΣPBDE concentration had a highly significant correlation with ΣPCB, ΣCHL, dieldrin, HCB and ΣHCH concentrations. We found a seasonal pattern of median ΣPBDE concentration with 1.2 to 1.8 times higher concentrations in March to July than the rest of the year. The seasonal variation also provides a clue to the seasonal exposure, bio-availability, toxic exposure and degradation. We suggest that future geographical PBDE data comparisons may not need corrections for sex or age, but such data sets should be corrected for seasonal variability, using the presented correctional trigonometric regression. - Mean ΣPBDE concentrations of East Greenland polar bears (Ursus maritimus) were 69.5 ng/g lw (range: 21.7-192 ng/g lw) and showed a seasonal pattern with no relationship with age and sex

  8. Age and seasonal variability of polybrominated diphenyl ethers in free-ranging East Greenland polar bears (Ursus maritimus)

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, Rune [Department of Arctic Environment, National Environmental Research Institute, Frederiksborgvej 399, P.O. Box 358, DK-4000 Roskilde (Denmark)]. E-mail: rdi@dmu.dk; Riget, Frank F. [Department of Arctic Environment, National Environmental Research Institute, Frederiksborgvej 399, P.O. Box 358, DK-4000 Roskilde (Denmark); Sonne, Christian [Department of Arctic Environment, National Environmental Research Institute, Frederiksborgvej 399, P.O. Box 358, DK-4000 Roskilde (Denmark); Letcher, Robert J. [National Wildlife Research Centre, Science and Technology Branch, Environment Canada, Carleton University (Raven Road), Ottawa, ON, K1A 0H3 (Canada); Backus, Sean [Environment Canada, Water Science and Technology Directorate, Burlington, ON, L7R 4A6 (Canada); Born, Erik W. [Greenland Institute of Natural Resources, P.O. Box 570, DK-3900 Nuuk, Greenland (Denmark); Kirkegaard, Maja [Department of Arctic Environment, National Environmental Research Institute, Frederiksborgvej 399, P.O. Box 358, DK-4000 Roskilde (Denmark); Muir, Derek C.G. [Environment Canada, Water Science and Technology Directorate, Burlington, ON, L7R 4A6 (Canada)

    2007-03-15

    Polybrominated diphenyl ethers (PBDEs) were analysed in adipose tissue from 92 East Greenland polar bears (Ursus maritimus) sampled during 1999-2001. Mean {sigma}PBDE concentrations were 70 ng/g lipid weight (lw) (range: 22-192 ng/g lw) and showed no relationship with age or sex. Of the 32 analysed PBDE congeners; BDE47, BDE153, BDE99 and BDE100 dominated, and comprised 99.6% of the {sigma}PBDE concentration. The {sigma}PBDE concentration had a highly significant correlation with {sigma}PCB, {sigma}CHL, dieldrin, HCB and {sigma}HCH concentrations. We found a seasonal pattern of median {sigma}PBDE concentration with 1.2 to 1.8 times higher concentrations in March to July than the rest of the year. The seasonal variation also provides a clue to the seasonal exposure, bio-availability, toxic exposure and degradation. We suggest that future geographical PBDE data comparisons may not need corrections for sex or age, but such data sets should be corrected for seasonal variability, using the presented correctional trigonometric regression. - Mean {sigma}PBDE concentrations of East Greenland polar bears (Ursus maritimus) were 69.5 ng/g lw (range: 21.7-192 ng/g lw) and showed a seasonal pattern with no relationship with age and sex.

  9. Brain region distribution and patterns of bioaccumulative perfluoroalkyl carboxylates and sulfonates in east greenland polar bears (Ursus maritimus).

    Science.gov (United States)

    Greaves, Alana K; Letcher, Robert J; Sonne, Christian; Dietz, Rune

    2013-03-01

    The present study investigated the comparative accumulation of perfluoroalkyl acids (PFAAs) in eight brain regions of polar bears (Ursus maritimus, n = 19) collected in 2006 from Scoresby Sound, East Greenland. The PFAAs studied were perfluoroalkyl carboxylates (PFCAs, C(6) -C(15) chain lengths) and sulfonates (C(4) , C(6) , C(8) , and C(10) chain lengths) as well as selected precursors including perfluorooctane sulfonamide. On a wet-weight basis, blood-brain barrier transport of PFAAs occurred for all brain regions, although inner regions of the brain closer to incoming blood flow (pons/medulla, thalamus, and hypothalamus) contained consistently higher PFAA concentrations compared to outer brain regions (cerebellum, striatum, and frontal, occipital, and temporal cortices). For pons/medulla, thalamus, and hypothalamus, the most concentrated PFAAs were perfluorooctane sulfonate (PFOS), ranging from 47 to 58 ng/g wet weight, and perfluorotridecanoic acid, ranging from 43 to 49 ng/g wet weight. However, PFOS and the longer-chain PFCAs (C(10) -C(15) ) were significantly (p  0.05) different among brain regions. The burden of the sum of PFCAs, perfluoroalkyl sulfonates, and perfluorooctane sulfonamide in the brain (average mass, 392 g) was estimated to be 46 µg. The present study demonstrates that both PFCAs and perfluoroalkyl sulfonates cross the blood-brain barrier in polar bears and that wet-weight concentrations are brain region-specific. Copyright © 2012 SETAC.

  10. Hardness and softness reactivity kernels within the spin-polarized density-functional theory

    International Nuclear Information System (INIS)

    Chamorro, Eduardo; De Proft, Frank; Geerlings, Paul

    2005-01-01

    Generalized hardness and softness reactivity kernels are defined within a spin-polarized density-functional theory (SP-DFT) conceptual framework. These quantities constitute the basis for the global, local (i.e., r-position dependent), and nonlocal (i.e., r and r ' -position dependents) indices devoted to the treatment of both charge-transfer and spin-polarization processes in such a reactivity framework. The exact relationships between these descriptors within a SP-DFT framework are derived and the implications for chemical reactivity in such context are outlined

  11. Consequences of severe habitat fragmentation on density, genetics, and spatial capture-recapture analysis of a small bear population.

    Directory of Open Access Journals (Sweden)

    Sean M Murphy

    Full Text Available Loss and fragmentation of natural habitats caused by human land uses have subdivided several formerly contiguous large carnivore populations into multiple small and often isolated subpopulations, which can reduce genetic variation and lead to precipitous population declines. Substantial habitat loss and fragmentation from urban development and agriculture expansion relegated the Highlands-Glades subpopulation (HGS of Florida, USA, black bears (Ursus americanus floridanus to prolonged isolation; increasing human land development is projected to cause ≥ 50% loss of remaining natural habitats occupied by the HGS in coming decades. We conducted a noninvasive genetic spatial capture-recapture study to quantitatively describe the degree of contemporary habitat fragmentation and investigate the consequences of habitat fragmentation on population density and genetics of the HGS. Remaining natural habitats sustaining the HGS were significantly more fragmented and patchier than those supporting Florida's largest black bear subpopulation. Genetic diversity was low (AR = 3.57; HE = 0.49 and effective population size was small (NE = 25 bears, both of which remained unchanged over a period spanning one bear generation despite evidence of some immigration. Subpopulation density (0.054 bear/km2 was among the lowest reported for black bears, was significantly female-biased, and corresponded to a subpopulation size of 98 bears in available habitat. Conserving remaining natural habitats in the area occupied by the small, genetically depauperate HGS, possibly through conservation easements and government land acquisition, is likely the most important immediate step to ensuring continued persistence of bears in this area. Our study also provides evidence that preferentially placing detectors (e.g., hair traps or cameras primarily in quality habitat across fragmented landscapes poses a challenge to estimating density-habitat covariate relationships using spatial

  12. Consequences of severe habitat fragmentation on density, genetics, and spatial capture-recapture analysis of a small bear population.

    Science.gov (United States)

    Murphy, Sean M; Augustine, Ben C; Ulrey, Wade A; Guthrie, Joseph M; Scheick, Brian K; McCown, J Walter; Cox, John J

    2017-01-01

    Loss and fragmentation of natural habitats caused by human land uses have subdivided several formerly contiguous large carnivore populations into multiple small and often isolated subpopulations, which can reduce genetic variation and lead to precipitous population declines. Substantial habitat loss and fragmentation from urban development and agriculture expansion relegated the Highlands-Glades subpopulation (HGS) of Florida, USA, black bears (Ursus americanus floridanus) to prolonged isolation; increasing human land development is projected to cause ≥ 50% loss of remaining natural habitats occupied by the HGS in coming decades. We conducted a noninvasive genetic spatial capture-recapture study to quantitatively describe the degree of contemporary habitat fragmentation and investigate the consequences of habitat fragmentation on population density and genetics of the HGS. Remaining natural habitats sustaining the HGS were significantly more fragmented and patchier than those supporting Florida's largest black bear subpopulation. Genetic diversity was low (AR = 3.57; HE = 0.49) and effective population size was small (NE = 25 bears), both of which remained unchanged over a period spanning one bear generation despite evidence of some immigration. Subpopulation density (0.054 bear/km2) was among the lowest reported for black bears, was significantly female-biased, and corresponded to a subpopulation size of 98 bears in available habitat. Conserving remaining natural habitats in the area occupied by the small, genetically depauperate HGS, possibly through conservation easements and government land acquisition, is likely the most important immediate step to ensuring continued persistence of bears in this area. Our study also provides evidence that preferentially placing detectors (e.g., hair traps or cameras) primarily in quality habitat across fragmented landscapes poses a challenge to estimating density-habitat covariate relationships using spatial capture

  13. Consequences of long-distance swimming and travel over deep-water pack ice for a female polar bear during a year of extreme sea ice retreat

    Science.gov (United States)

    Durner, G.M.; Whiteman, J.P.; Harlow, H.J.; Amstrup, Steven C.; Regehr, E.V.; Ben-David, M.

    2011-01-01

    Polar bears (Ursus maritimus) prefer to live on Arctic sea ice but may swim between ice floes or between sea ice and land. Although anecdotal observations suggest that polar bears are capable of swimming long distances, no data have been available to describe in detail long distance swimming events or the physiological and reproductive consequences of such behavior. Between an initial capture in late August and a recapture in late October 2008, a radio-collared adult female polar bear in the Beaufort Sea made a continuous swim of 687 km over 9 days and then intermittently swam and walked on the sea ice surface an additional 1,800 km. Measures of movement rate, hourly activity, and subcutaneous and external temperature revealed distinct profiles of swimming and walking. Between captures, this polar bear lost 22% of her body mass and her yearling cub. The extraordinary long distance swimming ability of polar bears, which we confirm here, may help them cope with reduced Arctic sea ice. Our observation, however, indicates that long distance swimming in Arctic waters, and travel over deep water pack ice, may result in high energetic costs and compromise reproductive fitness. ?? 2011 US Government.

  14. The role of Pleistocene glaciations in shaping the evolution of polar and brown bears. Evidence from a critical review of mitochondrial and nuclear genome analyses.

    Science.gov (United States)

    Hassanin, Alexandre

    2015-07-01

    In this report, I review recent molecular studies dealing with the origin and evolution of polar bears (Ursus maritimus), with special emphasis on their relationships with brown bears (U. arctos). On the basis of mitochondrial and nuclear data, different hypotheses have been proposed, including rapid morphological differentiation of U. maritimus, genetic introgression from U. arctos into U. maritimus, or inversely from U. maritimus into U. arctos, involving either male- or female-mediated gene flow. In the light of available molecular and eco-ethological data, I suggest, firstly, that all divergences among major clades of large bears can be linked to glacial periods, secondly, that polar bears diverged from brown bears before 530 thousand years ago (ka), during one of the three glacial marine isotope stages (MIS) 14, 15.2 or 16, and, thirdly, that genetic introgression had occurred from female polar bears into brown bear populations during at least two glacial periods, at 340 ± 10 ka (MIS 10) in western Europe, and at 155 ± 5 ka (MIS 6) on the ABC islands of southeastern Alaska, and probably also in Beringia and Ireland based on ancient DNA sequences. Copyright © 2015 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  15. Variation in the response of an Arctic top predator experiencing habitat loss: feeding and reproductive ecology of two polar bear populations

    Science.gov (United States)

    Rode, Karyn D.; Regehr, Eric V.; Douglas, David C.; Durner, George; Derocher, Andrew E.; Thiemann, Gregory W.; Budge, Suzanne M.

    2014-01-01

    Polar bears (Ursus maritimus) have experienced substantial changes in the seasonal availability of sea ice habitat in parts of their range, including the Beaufort, Chukchi, and Bering Seas. In this study, we compared the body size, condition, and recruitment of polar bears captured in the Chukchi and Bering Seas (CS) between two periods (1986–1994 and 2008–2011) when declines in sea ice habitat occurred. In addition, we compared metrics for the CS population 2008–2011 with those of the adjacent southern Beaufort Sea (SB) population where loss in sea ice habitat has been associated with declines in body condition, size, recruitment, and survival. We evaluated how variation in body condition and recruitment were related to feeding ecology. Comparing habitat conditions between populations, there were twice as many reduced ice days over continental shelf waters per year during 2008–2011 in the SB than in the CS. CS polar bears were larger and in better condition, and appeared to have higher reproduction than SB bears. Although SB and CS bears had similar diets, twice as many bears were fasting in spring in the SB than in the CS. Between 1986–1994 and 2008–2011, body size, condition, and recruitment indices in the CS were not reduced despite a 44-day increase in the number of reduced ice days. Bears in the CS exhibited large body size, good body condition, and high indices of recruitment compared to most other populations measured to date. Higher biological productivity and prey availability in the CS relative to the SB, and a shorter recent history of reduced sea ice habitat, may explain the maintenance of condition and recruitment of CS bears. Geographic differences in the response of polar bears to climate change are relevant to range-wide forecasts for this and other ice-dependent species.

  16. Distribution of vitamins A (retinol) and E (α-tocopherol) in polar bear kidney: Implications for biomarker studies.

    Science.gov (United States)

    Bechshøft, T Ø; Jakobsen, J; Sonne, C; Dietz, R

    2011-08-15

    Vitamins A and E content of inner organs, among these the kidneys, are increasingly being used as an indicator of adverse effects caused to the organism by e.g. environmental contaminants. In general, only a renal sub sample is used for analyses, and it is thus essential to know which part of the organ to sample in order to get a representative value for this important biomarker. The aim here was to assess the distribution of vitamins A (retinol) and E (α-tocopherol) within the polar bear multireniculate kidney (i.e. polar vs. medial position) and also within the cortex vs. medulla of each separate renculi. The results showed no significant difference between the medial and polar renculi with regards to either retinol (p=0.44) or α-tocopherol (p=0.75). There were, however, significant differences between cortex and medulla for both vitamins (retinol, p=0.0003; α-tocopherol, pbear kidneys. Prior to analysis, the renculi should be separated into medulla and cortex. The results indicated no significant differences between renculi from different parts of the kidney. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Chlorinated hydrocarbon contaminants in polar bears from eastern Russia, North America, Greenland, and Svalbard: biomonitoring of Arctic pollution.

    Science.gov (United States)

    Norstrom, R J; Belikov, S E; Born, E W; Garner, G W; Malone, B; Olpinski, S; Ramsay, M A; Schliebe, S; Stirling, I; Stishov, M S; Taylor, M K; Wiig, O

    1998-08-01

    Adipose tissue samples from polar bears (Ursus maritimus) were obtained by necropsy or biopsy between the spring of 1989 to the spring of 1993 from Wrangel Island in Russia, most of the range of the bear in North America, eastern Greenland, and Svalbard. Samples were divided into 16 regions corresponding as much as possible to known stocks or management zones. Concentrations of dieldrin (DIEL), 4,4'-DDE (DDE), sum of 16 polychlorinated biphenyl congeners (sigma PCB), and sum of 11 chlordane-related compounds and metabolites (sigma CHL) were determined. In order to minimize the effect of age, only data for adults (320 bears age 5 years and older) was used to compare concentrations among regions. Concentrations of sigma PCB were 46% higher in adult males than females, and there was no significant trend with age. Concentrations of sigma CHL were 30% lower in adult males than females. Concentrations of sigma PCB, sigma CHL, and DDE in individual adult female bears were standardized to adult males using factors derived from the least-square means of each sex category, and geometric means of the standardized concentrations on a lipid weight basis were compared among regions. Median geometric mean standardized concentrations (lipid weight basis) and ranges among regions were as follows: sigma PCB, 5,942 (2,763-24,316) micrograms/kg; sigma CHL, 1,952 (727-4,632) micrograms/kg; DDE, 219 (52-560) micrograms/kg; DIEL, 157 (31-335) micrograms/kg. Geometric mean sigma PCB concentrations in bears from Svalbard, East Greenland, and the Arctic Ocean near Prince Patrick Island in Canada were similar (20,256-24,316 micrograms/kg) and significantly higher than most other areas. Atmospheric, oceanic, and ice transport, as well as ecological factors may contribute to these high concentrations of sigma PCB. sigma CHL was more uniformly distributed among regions than the other CHCs. Highest sigma CHL concentrations were found in southeastern Hudson Bay, which also had the highest DDE and

  18. Polarization Potential Has No Effect on Maximum Current Density Produced by Halotolerant Bioanodes

    Directory of Open Access Journals (Sweden)

    Muriel González-Muñoz

    2018-03-01

    Full Text Available Halotolerant bioanodes are considered an attractive alternative in microbial electrochemical systems, as they can operate under higher conductive electrolytes, in comparison with traditional wastewater and freshwater bioanodes. The dependency between energetic performance and polarization potential has been addressed in several works; however the vast majority discusses its effect when wastewater or freshwater inocula are employed, and fewer reports focus on inocula from highly-saline environments. Moreover, the effect of the polarization potential on current production is not fully understood. To determine if the polarization potential has a significant effect on current production, eight bioanodes were grown by chronoamperometry at positive and negative potentials relative to the reference electrode (+0.34 V/SHE and −0.16 V/SHE, in a three-electrode set-up employing sediments from a hyperhaline coastal lagoon. The maximum current density obtained was the same, despite the differences in the applied potential. Our findings indicate that even if differences in organic matter removal and coulombic efficiency are obtained, the polarization potential had no statistically significant effect on overall current density production.

  19. Thermal inertia and radar reflectivity of the Martian north polar ERG: Low-density aggregates

    Science.gov (United States)

    Herkenhoff, K. E.

    1993-01-01

    The north polar layered deposits on Mars appear to be the source of the dark material that comprises the north polar erg. The physical properties and chemical composition of the erg material therefore have important implications for the origin and evolution of the Martian layered deposits. Viking bistatic radar and infrared thermal mapping (IRTM) data indicate that the bulk density of the erg material is lower than that of the average Martian surface. These data are consistent with hypotheses involving formation of filamentary sublimation residue (FSR) particles from erosion of the layered deposits. The color and albedo of the erg and of the layered deposits, and the presence of magnetic material on Mars, suggest that the dark material is composed of low-density aggregates of magnetic dust grains, perhaps similar to FSR particles created in laboratory experiments.

  20. Brain region-specific perfluoroalkylated sulfonate (PFSA) and carboxylic acid (PFCA) accumulation and neurochemical biomarker Responses in east Greenland polar Bears (Ursus maritimus)

    DEFF Research Database (Denmark)

    Pedersen, Kathrine Eggers; Basu, Niladri; Letcher, Robert

    2015-01-01

    was 88ng/g ww where PFUnDA, PFDoDA and PFTrDA combined accounted for 79%. The highest concentrations of PFASs were measured in brain stem, cerebellum and hippocampus. Correlative analyses were performed both across and within brain regions. Significant positive correlations were found between PFASs...... to bioaccumulate in lipid rich tissues of the brain among other tissues such as liver, and can reach high concentrations in top predators including the polar bear. PFCA and PFSA bioaccummulation in the brain has the potential to pose neurotoxic effects and therefore we conducted a study to investigate...... if variations in neurochemical transmitter systems i.e. the cholinergic, glutaminergic, dopaminergic and GABAergic, could be related to brain-specific bioaccumulation of PFASs in East Greenland polar bears. Nine brain regions from nine polar bears were analyzed for enzyme activity (monoamine oxidase (MAO...

  1. Vitamins A and E in liver, kidney, and whole blood of East Greenland polar bears sampled 1994–2008: reference values and temporal trends

    DEFF Research Database (Denmark)

    Bechshoft, T.; Sonne, C.; Jakobsen, Jette

    2015-01-01

    that POPs could be disrupting polar bear vitamin status. However, while the observed temporal increases in vitamin concentrations were likely POP related, the question remains as to whether they stem from influence of contaminants only or also, e.g., changes in prey species. Further studies are needed......Vitamins A (retinol) and E (α-tocopherol) are dietary vitamins, essential for, e.g., growth and development, reproduction, and immune function. Persistent organic pollutants (POPs) have been found to be related to vitamin A and E metabolism. However, few investigations have been published...... on this health issue in polar bears (Ursus maritimus). The aim of this study was thus to provide reference values for concentrations of vitamin A in liver, kidney cortex, and whole blood and vitamin E in kidney cortex and whole blood from 166 East Greenland polar bears, as well as to assess the relationship...

  2. The endocrine disruption properties of an adipose contaminant mixture extracted from East Greenland polar bears studied in the H295R cell line

    DEFF Research Database (Denmark)

    Hjorth, R.; Letcher, R. J.; Blair, D.

    been well described and especially the polar bear (Ursus maritimus) is recognized as being one of the most contaminated species in the Arctic. The present study investigated the in vitro endocrine disruptive effects of the POP mixture found in adipose tissue from 10 East Greenland polar bears collected...... compounds, where some can be in the parts-perbillion (ppb) concentration range. However, most reported studies on endocrine disruption effects have been on single compounds at concentrations higher than environmentally relevant. The presence of persistent organic pollutants (POPs) in arctic wildlife has...... (dehydroepiandrosterone and androstenedione). These results demonstrated comprehensive in vitro effects of POPs extracted from polar bear adipose tissue on key elements in the steroidogenesis, and identifies disruption of CYP17 activity as a mode of action. A POP-induced interference with CYP17 can potentially explain...

  3. Polar Bears or People? Exploring Ways in Which Teachers Frame Climate Change in the Classroom

    Science.gov (United States)

    Busch, K. C.

    2016-01-01

    Not only will young adults bear the brunt of the effects of climate change, but they are also the ones who will be required to take action-to mitigate and to adapt. Framing, as both a theory and an analytic method, has been used to understand how language in the media can affect the audience's concern and intention to act. The theory and the…

  4. Reproductive performance in East Greenland polar bears (Ursus maritimus) may be affected by organohalogen contaminants as shown by physiologically-based pharmacokinetic (PBPK) modelling.

    Science.gov (United States)

    Sonne, Christian; Gustavson, Kim; Rigét, Frank F; Dietz, Rune; Birkved, Morten; Letcher, Robert J; Bossi, Rossana; Vorkamp, Katrin; Born, Erik W; Petersen, Gitte

    2009-12-01

    Polar bears (Ursus maritimus) feed mainly on ringed seal (Phoca hispida) and consume large quantities of blubber and consequently have one of the highest tissue concentrations of organohalogen contaminants (OHCs) worldwide. In East Greenland, studies of OHC time trends and organ system health effects, including reproductive, were conducted during 1990-2006. However, it has been difficult to determine the nature of the effects induced by OHC exposures on wild caught polar bears using body burden data and associated changes in reproductive organs and systems. We therefore conducted a risk quotient (RQ) evaluation to more quantitatively evaluate the effect risk on reproduction (embryotoxicity and teratogenicity) based on the critical body residue (CBR) concept and using a physiologically-based pharmacokinetic (PBPK) model. We applied modelling approaches to PCBs, p,p'-DDE, dieldrin, oxychlordane, HCHs, HCB, PBDEs and PFOS in East Greenland polar bears based on known OHC pharmacokinetics and dynamics in laboratory rats (Rattus rattus). The results showed that subcutaneous adipose tissue concentrations of dieldrin (range: 79-1271 ng g(-1) lw) and PCBs (range: 4128-53,923 ng g(-1) lw) reported in bears in the year 1990 were in the range to elicit possible adverse health effects on reproduction in polar bears in East Greenland (all RQs > or = 1). Similar results were found for PCBs (range: 1928-17,376 ng g(-1) lw) and PFOS (range: 104-2840 ng g(-1) ww) in the year 2000 and for dieldrin (range: 43-640 ng g(-1) lw), PCBs (range: 3491-13,243 ng g(-1) lw) and PFOS (range: 1332-6160 ng g(-1) ww) in the year 2006. The concentrations of oxychlordane, DDTs, HCB and HCHs in polar bears resulted in RQspolar bears correlated to OHC exposure are supported by the present study. This study also indicates that PBPK models may be a supportive tool in the evaluation of possible OHC-mediated health effects for Arctic wildlife.

  5. Global change effects on the long-term feeding ecology and contaminant exposures of East Greenland polar bears.

    Science.gov (United States)

    McKinney, Melissa A; Iverson, Sara J; Fisk, Aaron T; Sonne, Christian; Rigét, Frank F; Letcher, Robert J; Arts, Michael T; Born, Erik W; Rosing-Asvid, Aqqalu; Dietz, Rune

    2013-08-01

    Rapid climate changes are occurring in the Arctic, with substantial repercussions for arctic ecosystems. It is challenging to assess ecosystem changes in remote polar environments, but one successful approach has entailed monitoring the diets of upper trophic level consumers. Quantitative fatty acid signature analysis (QFASA) and fatty acid carbon isotope (δ(13) C-FA) patterns were used to assess diets of East Greenland (EG) polar bears (Ursus maritimus) (n = 310) over the past three decades. QFASA-generated diet estimates indicated that, on average, EG bears mainly consumed arctic ringed seals (47.5 ± 2.1%), migratory subarctic harp (30.6 ± 1.5%) and hooded (16.7 ± 1.3%) seals and rarely, if ever, consumed bearded seals, narwhals or walruses. Ringed seal consumption declined by 14%/decade over 28 years (90.1 ± 2.5% in 1984 to 33.9 ± 11.1% in 2011). Hooded seal consumption increased by 9.5%/decade (0.0 ± 0.0% in 1984 to 25.9 ± 9.1% in 2011). This increase may include harp seal, since hooded and harp seal FA signatures were not as well differentiated relative to other prey species. Declining δ(13) C-FA ratios supported shifts from more nearshore/benthic/ice-associated prey to more offshore/pelagic/open-water-associated prey, consistent with diet estimates. Increased hooded seal and decreased ringed seal consumption occurred during years when the North Atlantic Oscillation (NAO) was lower. Thus, periods with warmer temperatures and less sea ice were associated with more subarctic and less arctic seal species consumption. These changes in the relative abundance, accessibility, or distribution of arctic and subarctic marine mammals may have health consequences for EG polar bears. For example, the diet change resulted in consistently slower temporal declines in adipose levels of legacy persistent organic pollutants, as the subarctic seals have higher contaminant burdens than arctic seals. Overall, considerable changes are occurring in the EG

  6. Polyhalogenated compounds (PCBs, chlordanes, HCB and BFRs) in four polar bears (Ursus maritimus) that swam malnourished from East Greenland to Iceland.

    Science.gov (United States)

    Vetter, Walter; Gall, Vanessa; Skírnisson, Karl

    2015-11-15

    Levels of organohalogen compounds (PCBs, chlordane, PBB 153, PBDEs, HCB) were determined in adipose tissue, liver, kidney and muscle of four polar bears which swam and/or drifted to Iceland in extremely malnourished condition. Since the colonization in the 9th century polar bears have been repeatedly observed in Iceland. However, in recent years three of the animals have clearly left their natural habitat in poor condition in May or June, i.e. at the end of the major feeding season. The fourth bear is believed to have drifted with melting ice to North-Eastern Iceland in mid-winter. The concentrations of the POPs were within the range or higher than the typical concentrations measured in polar bears from the East Greenland population. In addition to the targeted compounds, we tentatively detected Dechlorane 602 and its potential hydrodechlorinated Cl11-metabolite in all samples. Moreover, a polychlorinated compound which partly co-eluted with PCB 209 was detected in all liver samples but not in adipose tissue, kidney or muscle. The mass spectrum of the potential metabolite did not allow determining its structure. Polar bears are good swimmers and can reach Iceland from the ice edge of East Greenland within a few days. Potential reasons for the swims are briefly discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Bioaccumulation and biotransformation of brominated and chlorinated contaminants and their metabolites in ringed seals (Pusa hispida) and polar bears (Ursus maritimus) from East Greenland.

    Science.gov (United States)

    Letcher, Robert J; Gebbink, Wouter A; Sonne, Christian; Born, Erik W; McKinney, Melissa A; Dietz, Rune

    2009-11-01

    We report on the comparative bioaccumulation, biotransformation and/or biomagnification from East Greenland ringed seal (Pusa hispida) blubber to polar bear (Ursus maritimus) tissues (adipose, liver and brain) of various classes and congeners of persistent chlorinated and brominated contaminants and metabolic by-products: polychlorinated biphenyls (PCBs), chlordanes (CHLs), hydroxyl (OH-) and methylsulfonyl (MeSO(2)-) PCBs, polybrominated biphenyls (PBBs), OH-PBBs, polybrominated diphenyl ether (PBDE) and hexabromocyclododecane (HBCD) flame retardants and OH- and methoxyl (MeO-) PBDEs, 2,2-dichloro-bis(4-chlorophenyl)ethene (p,p'-DDE), 3-MeSO(2)-p,p'-DDE, pentachlorophenol (PCP) and 4-OH-heptachlorostyrene (4-OH-HpCS). We detected all of the investigated contaminants in ringed seal blubber with high frequency, the main diet of East Greenland bears, with the exception of OH-PCBs and 4-OH-HpCS, which indicated that these phenolic contaminants were likely of metabolic origin and formed in the bears from accumulated PCBs and octachlorostyrene (OCS), respectively, rather than being bioaccumulated from a seal blubber diet. For all of the detectable sum of classes or individual organohalogens, in general, the ringed seal to polar bear mean BMFs for SigmaPCBs, p,p'-DDE, SigmaCHLs, SigmaMeSO(2)-PCBs, 3-MeSO(2)-p,p'-DDE, PCP, SigmaPBDEs, total-(alpha)-HBCD, SigmaOH-PBDEs, SigmaMeO-PBDEs and SigmaOH-PBBs indicated that these organohalogens bioaccumulate, and in some cases there was tissue-specific biomagnification, e.g., BMFs for bear adipose and liver ranged from 2 to 570. The blood-brain barrier appeared to be effective in minimizing brain accumulation as BMFs were bear tissues appeared to be mainly accumulated from the seal blubber rather than being metabolic formed from PBDEs in the bears. In vitro PBDE depletion assays using polar bear hepatic microsomes, wherein the rate of oxidative metabolism of PBDE congeners was very slow, supported the probability that accumulation

  8. Development of high-polarization Fe/Ge neutron polarizing supermirror: Possibility of fine-tuning of scattering length density in ion beam sputtering

    Science.gov (United States)

    Maruyama, R.; Yamazaki, D.; Akutsu, K.; Hanashima, T.; Miyata, N.; Aoki, H.; Takeda, M.; Soyama, K.

    2018-04-01

    The multilayer structure of Fe/Si and Fe/Ge systems fabricated by ion beam sputtering (IBS) was investigated using X-ray and polarized neutron reflectivity measurements and scanning transmission electron microscopy with energy-dispersive X-ray analysis. The obtained result revealed that the incorporation of sputtering gas particles (Ar) in the Ge layer gives rise to a marked reduction in the neutron scattering length density (SLD) and contributes to the SLD contrast between the Fe and Ge layers almost vanishing for spin-down neutrons. Bundesmann et al. (2015) have shown that the implantation of primary Ar ions backscattered at the target is responsible for the incorporation of Ar particles and that the fraction increases with increasing ion incidence angle and increasing polar emission angle. This leads to a possibility of fine-tuning of the SLD for the IBS, which is required to realize a high polarization efficiency of a neutron polarizing supermirror. Fe/Ge polarizing supermirror with m = 5 fabricated under the same condition showed a spin-up reflectivity of 0.70 at the critical momentum transfer. The polarization was higher than 0.985 for the qz range where the correction for the polarization inefficiencies of the beamline works properly. The result of the polarized neutron reflectivity measurement suggests that the "magnetically-dead" layers formed at both sides of the Fe layer, together with the SLD contrast, play a critical role in determining the polarization performance of a polarizing supermirror.

  9. Particle-bearing currents in uniform density and two-layer fluids

    Science.gov (United States)

    Sutherland, Bruce R.; Gingras, Murray K.; Knudson, Calla; Steverango, Luke; Surma, Christopher

    2018-02-01

    Lock-release gravity current experiments are performed to examine the evolution of a particle bearing flow that propagates either in a uniform-density fluid or in a two-layer fluid. In all cases, the current is composed of fresh water plus micrometer-scale particles, the ambient fluid is saline, and the current advances initially either over the surface as a hypopycnal current or at the interface of the two-layer fluid as a mesopycnal current. In most cases the tank is tilted so that the ambient fluid becomes deeper with distance from the lock. For hypopycnal currents advancing in a uniform density fluid, the current typically slows as particles rain out of the current. While the loss of particles alone from the current should increase the current's buoyancy and speed, in practice the current's speed decreases because the particles carry with them interstitial fluid from the current. Meanwhile, rather than settling on the sloping bottom of the tank, the particles form a hyperpycnal (turbidity) current that advances until enough particles rain out that the relatively less dense interstitial fluid returns to the surface, carrying some particles back upward. When a hypopycnal current runs over the surface of a two-layer fluid, the particles that rain out temporarily halt their descent as they reach the interface, eventually passing through it and again forming a hyperpycnal current. Dramatically, a mesopycnal current in a two-layer fluid first advances along the interface and then reverses direction as particles rain out below and fresh interstitial fluid rises above.

  10. Polar bear encephalitis: establishment of a comprehensive next-generation pathogen analysis pipeline for captive and free-living wildlife.

    Science.gov (United States)

    Szentiks, C A; Tsangaras, K; Abendroth, B; Scheuch, M; Stenglein, M D; Wohlsein, P; Heeger, F; Höveler, R; Chen, W; Sun, W; Damiani, A; Nikolin, V; Gruber, A D; Grobbel, M; Kalthoff, D; Höper, D; Czirják, G Á; Derisi, J; Mazzoni, C J; Schüle, A; Aue, A; East, M L; Hofer, H; Beer, M; Osterrieder, N; Greenwood, A D

    2014-05-01

    This report describes three possibly related incidences of encephalitis, two of them lethal, in captive polar bears (Ursus maritimus). Standard diagnostic methods failed to identify pathogens in any of these cases. A comprehensive, three-stage diagnostic 'pipeline' employing both standard serological methods and new DNA microarray and next generation sequencing-based diagnostics was developed, in part as a consequence of this initial failure. This pipeline approach illustrates the strengths, weaknesses and limitations of these tools in determining pathogen caused deaths in non-model organisms such as wildlife species and why the use of a limited number of diagnostic tools may fail to uncover important wildlife pathogens. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Images of Polar Bears and Penguins, Storms, Deforestation and More - Middle School Students Perceptions of Climate Change

    Science.gov (United States)

    Gopal, S.; Melaas, E. K.; Malmrose, M.; Mullokandov, A.

    2014-12-01

    Global change studies aim to foster a deeper understanding of the causes and consequences of global change on planet Earth. The study of global change presents a rich domain of inquiry, exploration, and discovery at all grade levels. The main objective of this exploratory study was to assess middle school students' perceptions of global change as part of their participation in the NSF GK12 program called GLACIER (Global Change Initiative - Education and Research) during the academic year 2012-13. The middle schools are located in the Metro Boston area. As part of the program, participating students were asked to draw pictures of their perceptions and ideas on global change. The drawings of 150 children, ages 11 to 13, were qualitatively analyzed. The analysis focused on (a) the type of concepts children chose to convey, (b) the specific context of the global change described (polar bears in floating glaciers), (c) students direct representation of anthropocentric impacts (such as pollution or deforestation), and (d) the match between students concepts and the recent IPCC reports. About 20% of the students focused on the iconic imagery of the melting glaciers and impact on animals such as penguins and polar bears, more than 25% focused on natural disasters (such as storms, sea level changes) while 30% focused on urban problems. These concepts are matched with the recent IPCC report. These results are notable and suggest students in middle schools understand the varied dimensions of global change and the role of human activities in bringing about change. Students' perspectives may help in developing a suitable curriculum using existing science standards to discuss this significant topic in middle school classrooms. In addition, students' drawings illustrate their perception of the coupled human and natural systems.

  12. Measuring environmental stress in East Greenland polar bears, 1892-1927 and 1988-2009: what does hair cortisol tell us?

    Science.gov (United States)

    Bechshøft, T Ø; Rigét, F F; Sonne, C; Letcher, R J; Muir, D C G; Novak, M A; Henchey, E; Meyer, J S; Eulaers, I; Jaspers, V L B; Eens, M; Covaci, A; Dietz, R

    2012-09-15

    Hair sampled from 96 East Greenland polar bears (Ursus maritimus) over the periods 1892-1927 and 1988-2009 was analyzed for cortisol as a proxy to investigate temporal patterns of environmental stress. Cortisol concentration was independent of sex and age, and was found at significantly higher (ppolar bear hair appears to be a relatively poor indicator of the animal's general POP load in adipose tissue. However, further investigations are warranted to explore the reasons for the temporal decrease found in the bears' hair cortisol levels. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Demographic and temporal variations in immunity and condition of polar bears (Ursus maritimus) from the southern Beaufort Sea.

    Science.gov (United States)

    Neuman-Lee, Lorin A; Terletzky, Patricia A; Atwood, Todd C; Gese, Eric M; Smith, Geoffrey D; Greenfield, Sydney; Pettit, John; French, Susannah S

    2017-06-01

    Assessing the health and condition of animals in their natural environment can be problematic. Many physiological metrics, including immunity, are highly influenced by specific context and recent events to which researchers may be unaware. Thus, using a multifaceted physiological approach and a context-specific analysis encompassing multiple time scales can be highly informative. Ecoimmunological tools in particular can provide important indications to the health of animals in the wild. We collected blood and hair samples from free-ranging polar bears (Ursus maritimus) in the southern Beaufort Sea and examined the influence of sex, age, and reproductive status on metrics of immunity, stress, and body condition during 2013-2015. We examined metrics of innate immunity (bactericidal ability and lysis) and stress (hair cortisol, reactive oxygen species, and oxidative barrier), in relation to indices of body condition considered to be short term (urea to creatinine ratio; UC ratio) and long term (storage energy and body mass index). We found the factors of sex, age, and reproductive status of the bear were critical for interpreting different physiological metrics. Additionally, the metrics of body condition were important predictors for stress indicators. Finally, many of these metrics differed between years, illustrating the need to examine populations on a longer time scale. Taken together, this study demonstrates the complex relationship between multiple facets of physiology and how interpretation requires us to examine individuals within a specific context. © 2017 Wiley Periodicals, Inc.

  14. Demographic and temporal variations in immunity and condition of polar bears (Ursus maritimus) from the southern Beaufort Sea

    Science.gov (United States)

    Neuman-Lee, Lorin; Terletzky, Patricia; Atwood, Todd C.; Gese, Eric; Smith, Geoffrey; Greenfield, Sydney; Pettit, John; French, Susannah

    2017-01-01

    Assessing the health and condition of animals in their natural environment can be problematic. Many physiological metrics, including immunity, are highly influenced by specific context and recent events to which researchers may be unaware. Thus, using a multifaceted physiological approach and a context-specific analysis encompassing multiple time scales can be highly informative. Ecoimmunological tools in particular can provide important indications to the health of animals in the wild. We collected blood and hair samples from free-ranging polar bears (Ursus maritimus) in the southern Beaufort Sea and examined the influence of sex, age, and reproductive status on metrics of immunity, stress, and body condition during 2013–2015. We examined metrics of innate immunity (bactericidal ability and lysis) and stress (hair cortisol, reactive oxygen species, and oxidative barrier), in relation to indices of body condition considered to be short term (urea to creatinine ratio; UC ratio) and long term (storage energy and body mass index). We found the factors of sex, age, and reproductive status of the bear were critical for interpreting different physiological metrics. Additionally, the metrics of body condition were important predictors for stress indicators. Finally, many of these metrics differed between years, illustrating the need to examine populations on a longer time scale. Taken together, this study demonstrates the complex relationship between multiple facets of physiology and how interpretation requires us to examine individuals within a specific context.

  15. An Arctic predator-prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals.

    Science.gov (United States)

    Hamilton, Charmain D; Kovacs, Kit M; Ims, Rolf A; Aars, Jon; Lydersen, Christian

    2017-09-01

    Climate change is impacting different species at different rates, leading to alterations in biological interactions with ramifications for wider ecosystem functioning. Understanding these alterations can help improve predictive capacity and inform management efforts designed to mitigate against negative impacts. We investigated how the movement and space use patterns of polar bears (Ursus maritimus) in coastal areas in Svalbard, Norway, have been altered by a sudden decline in sea ice that occurred in 2006. We also investigated whether the spatial overlap between polar bears and their traditionally most important prey, ringed seals (Pusa hispida), has been affected by the sea-ice decline, as polar bears are dependent on a sea-ice platform for hunting seals. We attached biotelemetry devices to ringed seals (n = 60, both sexes) and polar bears (n = 67, all females) before (2002-2004) and after (2010-2013) a sudden decline in sea ice in Svalbard. We used linear mixed-effects models to evaluate the association of these species to environmental features and an approach based on Time Spent in Area to investigate changes in spatial overlap between the two species. Following the sea-ice reduction, polar bears spent the same amount of time close to tidal glacier fronts in the spring but less time in these areas during the summer and autumn. However, ringed seals did not alter their association with glacier fronts during summer, leading to a major decrease in spatial overlap values between these species in Svalbard's coastal areas. Polar bears now move greater distances daily and spend more time close to ground-nesting bird colonies, where bear predation can have substantial local effects. Our results indicate that sea-ice declines have impacted the degree of spatial overlap and hence the strength of the predator-prey relationship between polar bears and ringed seals, with consequences for the wider Arctic marine and terrestrial ecosystems. Shifts in ecological

  16. Physiologically-based pharmacokinetic modelling of immune, reproductive and carcinogenic effects from contaminant exposure in polar bears (Ursus maritimus) across the Arctic.

    Science.gov (United States)

    Dietz, Rune; Gustavson, Kim; Sonne, Christian; Desforges, Jean-Pierre; Rigét, Frank F; Pavlova, Viola; McKinney, Melissa A; Letcher, Robert J

    2015-07-01

    Polar bears (Ursus maritimus) consume large quantities of seal blubber and other high trophic marine mammals and consequently have some of the highest tissue concentrations of organohalogen contaminants (OHCs) among Arctic biota. In the present paper we carried out a risk quotient (RQ) evaluation on OHC-exposed polar bears harvested from 1999 to 2008 and from 11 circumpolar subpopulations spanning from Alaska to Svalbard in order to evaluate the risk of OHC-mediated reproductive effects (embryotoxicity, teratogenicity), immunotoxicity and carcinogenicity (genotoxicity). This RQ evaluation was based on the Critical Body Residue (CBR) concept and a Physiologically-Based Pharmacokinetic Modelling (PBPK) approach using OHC concentrations measured in polar bear adipose or liver tissue. The range of OHC concentrations within polar bear populations were as follows for adipose, sum polychlorinated biphenyls ∑PCBs (1797-10,537 ng/g lw), sum methylsulphone-PCB ∑MeSO2-PCBs (110-672 ng/g lw), sum chlordanes ∑CHLs (765-3477 ng/g lw), α-hexachlorocyclohexane α-HCH (8.5-91.3 ng/g lw), β-hexachlorocyclohexane β-HCH (65.5-542 ng/g lw), sum chlorbenzenes ∑ClBzs (145-304 ng/g lw), dichlorodiphenyltrichloroethane ∑DDTs (31.5-206 ng/g lw), dieldrin (69-249 ng/g lw), polybrominated diphenyl ethers ∑PBDEs (4.6-78.4 ng/g lw). For liver, the perfluorooctanesulfonic acid (PFOS) concentrations ranged from 231-2792 ng/g ww. The total additive RQ from all OHCs ranged from 4.3 in Alaska to 28.6 in East Greenland bears for effects on reproduction, immune health and carcinogenicity, highlighting the important result that the toxic effect threshold (i.e. RQ>1) was exceeded for all polar bear populations assessed. PCBs were the main contributors for all three effect categories, contributing from 70.6% to 94.3% of the total risk and a RQ between 3.8-22.5. ∑MeSO2-PCBs were the second highest effect contributor for reproductive and immunological effects (0.17polar bears. We therefore

  17. Morbillivirus and Toxoplasma exposure and association with hematological parameters for southern Beaufort Sea polar bears: potential response to infectious agents in a sentinel species.

    Science.gov (United States)

    Kirk, Cassandra M; Amstrup, Steven; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M

    2010-09-01

    Arctic temperatures are increasing in response to greenhouse gas forcing and polar bears have already responded to changing conditions. Declines in body stature and vital rates have been linked to warming-induced loss of sea-ice. As food webs change and human activities respond to a milder Arctic, exposure of polar bears and other arctic marine organisms to infectious agents may increase. Because of the polar bear's status as arctic ecosystem sentinel, polar bear health could provide an index of changing pathogen occurrence throughout the Arctic, however, exposure and monitoring protocols have yet to be established. We examine prevalence of antibodies to Toxoplasma gondii, and four morbilliviruses (canine distemper [CDV], phocine distemper [PDV], dolphin morbillivirus [DMV], porpoise morbillivirus [PMV]) including risk factors for exposure. We also examine the relationships between antibody levels and hematologic values established in the previous companion article. Antibodies to Toxoplasma gondii and morbilliviruses were found in both sample years. We found a significant inverse relationship between CDV titer and total leukocytes, neutrophils, monocytes, and eosinophils, and a significant positive relationship between eosinophils and Toxoplasma gondii antibodies. Morbilliviral prevalence varied significantly among age cohorts, with 1-2 year olds least likely to be seropositive and bears aged 5-7 most likely. Data suggest that the presence of CDV and Toxoplasma gondii antibodies is associated with polar bear hematologic values. We conclude that exposure to CDV-like antigen is not randomly distributed among age classes and suggest that differing behaviors among life history stages may drive probability of specific antibody presence.

  18. Imaging of fast moving electron-density structures in the polar cap

    Directory of Open Access Journals (Sweden)

    C. N. Mitchell

    2007-06-01

    Full Text Available The imaging of fast-moving electron-density structures in the polar cap presents a unique set of challenges that are not encountered in other ionospheric imaging problems. GPS observations of total electron content in the polar cap are sparse compared to other regions in the Northern Hemisphere. Furthermore, the slow relative motion of the satellites across the sky complicates the problem since the velocity of the plasma can be large in comparison and traditional approaches could result in image blurring. This paper presents a Kalman-filter based method that incorporates a forward projection of the solution based on a model plasma drift velocity field. This is the first time that the plasma motion, rather than just integrations of electron density, has been used in an ionospheric imaging algorithm. The motion is derived from the Weimer model of the electric field. It is shown that this novel approach to the implementation of a Kalman filter provides a detailed view of the polar cap ionosphere under severe storm conditions. A case study is given for the October 2003 Halloween storm where verification is provided by incoherent scatter radars.

  19. Occurrence Locations, Dipole Tilt Angle Effects, and Plasma Cloud Drift Paths of Polar Cap Neutral Density Anomalies

    Science.gov (United States)

    Lin, C. S.; Sutton, E. K.; Huang, C. Y.; Cooke, D. L.

    2018-02-01

    Polar cap neutral density anomaly (PCNDA) with large mass density enhancements over the background has been frequently observed in the polar cap during magnetic storms. By tracing field lines to the magnetosphere from the polar ionosphere, we divide the polar cap into two regions, an open field line (OFL) region with field lines connecting to the magnetopause boundary and a distant tail field line (TFL) region threaded with magnetotail lobe field lines. A statistical study of neutral density observed by the Challenging Minisatellite Payload satellite during major magnetic storms with Dst atmospheric disturbance could be generated in the nightside polar cap. From the PCNDA size and speed of sound at 400 km, we derive an initial energy deposition duration for producing traveling atmospheric disturbance in the range from 0.5 to 2.5 hr.

  20. Reproductive performance in East Greenland polar bears (Ursus maritimus) may be affected by organohalogen contaminants as shown by physiologically-based pharmacokinetic (PBPK) modelling

    DEFF Research Database (Denmark)

    Sonne, Christian; Gustavson, Kim; Rigét, Frank F.

    2009-01-01

    Polar bears (Ursus maritimus) feed mainly on ringed seal (Phoca hispida) and consume large quantities of blubber and consequently have one of the highest tissue concentrations of organohalogen contaminants (OHCs) worldwide. In East Greenland, studies of OHC time trends and organ system health eff...

  1. Formal behavioral evaluation of enrichment programs on a zookeeper's schedule: a case study with a polar bear (Ursus Maritimus) at the Bronx Zoo.

    Science.gov (United States)

    Canino, Wendy; Powell, David

    2010-01-01

    We conducted a brief study of the effectiveness of environmental enrichment for a polar bear at the Bronx Zoo with two objectives in mind. First we wanted to determine if a novel method of collecting data that easily fits into a zookeeper's work routine would produce usable data and if so, we wanted to evaluate the effectiveness of some new items that had been purchased for enriching the polar bear in reducing his pacing behavior. Observations were recorded for 119 days over a period of 5 months from April 2007 through August 2007. Five new items and eight previously used items were rotated and presented to the polar bear in the morning and afternoon. We recorded the bear's behavior five times per day as we passed by his exhibit during our regular work routine. Predictably, we found that the newer enrichment items were more effective at increasing play and decreasing pacing, as well as other more subtle effects on his behavior that helped us to design a better enrichment routine. More importantly, we found that this method of "multi-point scan sampling" was effective at producing ample and reliable data that could be used to analyze the bear's behavior without adding significant work to the keepers' daily routine. (c) 2009 Wiley-Liss, Inc.

  2. Getting past the penguins and polar bears - comparing marine research in the Arctic and Antarctic

    Science.gov (United States)

    Stevenoski, S.; Lawver, L.; van Avendonk, H.

    2006-12-01

    The University of Texas Institute for Geophysics is actively involved in marine geophysics research in the Arctic and Antarctic. Over the past 11 years teachers have participated in a number of research cruises as part of their effort to do outreach and involve K-12 teachers directly in the science. This presentation will focus on comparing the differences in weather, ice, seafloor, and biology, observed by one teacher/researcher who participated in seismic cruises in western Arctic and the Bransfield Straight and the Ross Sea in Antarctica. The presentation will focus on how these differences and similarities affect the process of conducting science in these extreme environments. Attention will be placed on describing how aspects of this polar research can be incorporated into a K-12 science curriculum. A discussion of the continuing outreach by the scientists and university will also be included.

  3. Collar temperature sensor data reveal long-term patterns in southern Beaufort Sea polar bear den distribution on pack ice and land

    Science.gov (United States)

    Olson, Jay W; Rode, Karyn D.; Eggett, Dennis L.; Smith, T.S.; Wilson, R. R.; Durner, George M.; Fischbach, Anthony; Atwood, Todd C.; Douglas, David

    2017-01-01

    In response to a changing climate, many species alter habitat use. Polar bears Ursus maritimus in the southern Beaufort Sea have increasingly used land for maternal denning. To aid in detecting denning behavior, we developed an objective method to identify polar bear denning events using temperature sensor data collected by satellite-linked transmitters deployed on adult females between 1985 and 2013. We then applied this method to determine whether southern Beaufort Sea polar bears have continued to increase land denning with recent sea-ice loss and examined whether sea-ice conditions affect the distribution of dens between pack-ice and coastal substrates. Because land use in summer and autumn has also increased, we examined potential associations between summering substrate and denning substrate. Statistical process control methods applied to temperature-sensor data identified denning events with 94.5% accuracy in comparison to direct observations (n = 73) and 95.7% accuracy relative to subjective classifications based on temperature, location, and activity sensor data (n = 116). We found an increase in land-based denning during the study period. The frequency of land denning was directly related to the distance that sea ice retreated from the coast. Among females that denned, all 14 that summered on land subsequently denned there, whereas 29% of the 69 bears summering on ice denned on land. These results suggest that denning on land may continue to increase with further loss of sea ice. While the effects that den substrate have on nutrition, energetics, and reproduction are unclear, more polar bears denning onshore will likely increase human-bear interactions.

  4. East Greenland and Barents Sea polar bears (Ursus maritimus): adaptive variation between two populations using skull morphometrics as an indicator of environmental and genetic differences.

    Science.gov (United States)

    Pertoldi, Cino; Sonne, Christian; Wiig, Øystein; Baagøe, Hans J; Loeschcke, Volker; Bechshøft, Thea Østergaard

    2012-06-01

    A morphometric study was conducted on four skull traits of 37 male and 18 female adult East Greenland polar bears (Ursus maritimus) collected 1892-1968, and on 54 male and 44 female adult Barents Sea polar bears collected 1950-1969. The aim was to compare differences in size and shape of the bear skulls using a multivariate approach, characterizing the variation between the two populations using morphometric traits as an indicator of environmental and genetic differences. Mixture analysis testing for geographic differentiation within each population revealed three clusters for Barents Sea males and three clusters for Barents Sea females. East Greenland consisted of one female and one male cluster. A principal component analysis (PCA) conducted on the clusters defined by the mixture analysis, showed that East Greenland and Barents Sea polar bear populations overlapped to a large degree, especially with regards to females. Multivariate analyses of variance (MANOVA) showed no significant differences in morphometric means between the two populations, but differences were detected between clusters from each respective geographic locality. To estimate the importance of genetics and environment in the morphometric differences between the bears, a PCA was performed on the covariance matrix derived from the skull measurements. Skull trait size (PC1) explained approx. 80% of the morphometric variation, whereas shape (PC2) defined approx. 15%, indicating some genetic differentiation. Hence, both environmental and genetic factors seem to have contributed to the observed skull differences between the two populations. Overall, results indicate that many Barents Sea polar bears are morphometrically similar to the East Greenland ones, suggesting an exchange of individuals between the two populations. Furthermore, a subpopulation structure in the Barents Sea population was also indicated from the present analyses, which should be considered with regards to future management

  5. [Particle Size and Number Density Online Analysis for Particle Suspension with Polarization-Differentiation Elastic Light Scattering Spectroscopy].

    Science.gov (United States)

    Chen, Wei-kang; Fang, Hui

    2016-03-01

    The basic principle of polarization-differentiation elastic light scattering spectroscopy based techniques is that under the linear polarized light incidence, the singlely scattered light from the superficial biological tissue and diffusively scattered light from the deep tissue can be separated according to the difference of polarization characteristics. The novel point of the paper is to apply this method to the detection of particle suspension and, to realize the simultaneous measurement of its particle size and number density in its natural status. We design and build a coaxial cage optical system, and measure the backscatter signal at a specified angle from a polystyrene microsphere suspension. By controlling the polarization direction of incident light with a linear polarizer and adjusting the polarization direction of collected light with another linear polarizer, we obtain the parallel polarized elastic light scattering spectrum and cross polarized elastic light scattering spectrum. The difference between the two is the differential polarized elastic light scattering spectrum which include only the single scattering information of the particles. We thus compare this spectrum to the Mie scattering calculation and extract the particle size. We then also analyze the cross polarized elastic light scattering spectrum by applying the particle size already extracted. The analysis is based on the approximate expressions taking account of light diffusing, from which we are able to obtain the number density of the particle suspension. We compare our experimental outcomes with the manufacturer-provided values and further analyze the influence of the particle diameter standard deviation on the number density extraction, by which we finally verify the experimental method. The potential applications of the method include the on-line particle quality monitoring for particle manufacture as well as the fat and protein density detection of milk products.

  6. Morbillivirus and Toxoplasma exposure and association with hematological parameters for southern Beaufort Sea polar bears: potential response to infectious agents in a sentinel species

    Science.gov (United States)

    Kirk, Cassandra M.; Amstrup, Steven C.; Swor, Rhonda; Holcomb, Darce; O'Hara, Todd M.

    2010-01-01

    Arctic temperatures are increasing in response to greenhouse gas forcing and polar bears have already responded to changing conditions. Declines in body stature and vital rates have been linked to warming-induced loss of sea-ice. As food webs change and human activities respond to a milder Arctic, exposure of polar bears and other arctic marine organisms to infectious agents may increase. Because of the polar bear’s status as arctic ecosystem sentinel, polar bear health could provide an index of changing pathogen occurrence throughout the Arctic, however, exposure and monitoring protocols have yet to be established. We examine prevalence of antibodies to Toxoplasma gondii, and four morbilliviruses (canine distemper [CDV], phocine distemper [PDV], dolphin morbillivirus [DMV], porpoise morbillivirus [PMV]) including risk factors for exposure. We also examine the relationships between antibody levels and hematologic values established in the previous companion article. Antibodies to Toxoplasma gondii and morbilliviruses were found in both sample years. We found a significant inverse relationship between CDV titer and total leukocytes, neutrophils, monocytes, and eosinophils, and a significant positive relationship between eosinophils and Toxoplasma gondii antibodies. Morbilliviral prevalence varied significantly among age cohorts, with 1–2 year olds least likely to be seropositive and bears aged 5–7 most likely. Data suggest that the presence of CDV and Toxoplasma gondii antibodies is associated with polar bear hematologic values. We conclude that exposure to CDV-like antigen is not randomly distributed among age classes and suggest that differing behaviors among life history stages may drive probability of specific antibody presence.

  7. The Density of the North Polar Layered Deposit from Gravity and Topography

    Science.gov (United States)

    Ojha, L.; Lewis, K. W.

    2017-12-01

    The North Polar Layered Deposit (NPLD) of Mars is a vast reservoir of water ice with a volume of 1.14 million km3. Radar data indicates that the ice in the NPLD is extremely pure with dust content between 5 % to 10 %, however the radar data has not been able to put a direct constraint on the density of the NPLD. Here, we localize the gravity and topography signature of the NPLD and place a direct constraint on its density. We performed a grid search by generating admittance spectrum at each latitude and longitude between 75° N to 90° N and 0° E to 360° E, using a spherical cap of angular radius () of 7°, and a harmonic-bandwidth of the localization window Lwin of 37°. A region between Gemina Lingula and Planum Boreum was found to possesss an adequate correlation between gravity and topography. The estimated admittance spectra were compared with synthetic admittance spectra to constrain the load-density and the elastic thickness of the lithosphere. We constructed forward models by assuming that the lithosphere is a thin shell that deforms elastically in response to surface loads. We find that the bulk density of the NPLD ranges between 1000 to 1100 kg.m-3. Assuming a grain density of 3000 kg.m-3 for dust, the NPLD region within our localized window can contain dust content between 3 - 8 %, which is in an excellent agreement with the radar data.

  8. Magnetized Reverse Shock: Density-fluctuation-induced Field Distortion, Polarization Degree Reduction, and Application to GRBs

    Energy Technology Data Exchange (ETDEWEB)

    Deng Wei; Zhang Bing [Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States); Li Hui [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Stone, James M., E-mail: deng@physics.unlv.edu, E-mail: zhang@physics.unlv.edu, E-mail: hli@lanl.gov, E-mail: jstone@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544-1001 (United States)

    2017-08-10

    The early optical afterglow emission of several gamma-ray bursts (GRBs) shows a high linear polarization degree (PD) of tens of percent, suggesting an ordered magnetic field in the emission region. The light curves are consistent with being of a reverse shock (RS) origin. However, the magnetization parameter, σ , of the outflow is unknown. If σ is too small, an ordered field in the RS may be quickly randomized due to turbulence driven by various perturbations so that the PD may not be as high as observed. Here we use the “Athena++” relativistic MHD code to simulate a relativistic jet with an ordered magnetic field propagating into a clumpy ambient medium, with a focus on how density fluctuations may distort the ordered magnetic field and reduce PD in the RS emission for different σ values. For a given density fluctuation, we discover a clear power-law relationship between the relative PD reduction and the σ value of the outflow. Such a relation may be applied to estimate σ of the GRB outflows using the polarization data of early afterglows.

  9. In vivo and in vitro changes in neurochemical parameters related to mercury concentrations from specific brain regions of polar bears (Ursus maritimus).

    Science.gov (United States)

    Krey, Anke; Kwan, Michael; Chan, Hing Man

    2014-11-01

    Mercury (Hg) has been detected in polar bear brain tissue, but its biological effects are not well known. Relationships between Hg concentrations and neurochemical enzyme activities and receptor binding were assessed in the cerebellum, frontal lobes, and occipital lobes of 24 polar bears collected from Nunavik (Northern Quebec), Canada. The concentration-response relationship was further studied with in vitro experiments using pooled brain homogenate of 12 randomly chosen bears. In environmentally exposed brain samples, there was no correlative relationship between Hg concentration and cholinesterase (ChE) activity or muscarinic acetylcholine receptor (mAChR) binding in any of the 3 brain regions. Monoamine oxidase (MAO) activity in the occipital lobe showed a negative correlative relationship with total Hg concentration. In vitro experiments, however, demonstrated that Hg (mercuric chloride and methylmercury chloride) can inhibit ChE and MAO activities and muscarinic mAChR binding. These results show that Hg can alter neurobiochemical parameters but the current environmental Hg exposure level does have an effect on the neurochemistry of polar bears from northern Canada. © 2014 SETAC.

  10. Spatial and temporal trends of selected trace elements in liver tissue from polar bears (Ursus maritimus) from Alaska, Canada and Greenland.

    Science.gov (United States)

    Routti, Heli; Letcher, Robert J; Born, Erik W; Branigan, Marsha; Dietz, Rune; Evans, Thomas J; Fisk, Aaron T; Peacock, Elizabeth; Sonne, Christian

    2011-08-01

    Spatial trends and comparative changes in time of selected trace elements were studied in liver tissue from polar bears from ten different subpopulation locations in Alaska, Canadian Arctic and East Greenland. For nine of the trace elements (As, Cd, Cu, Hg, Mn, Pb, Rb, Se and Zn) spatial trends were investigated in 136 specimens sampled during 2005-2008 from bears from these ten subpopulations. Concentrations of Hg, Se and As were highest in the (northern and southern) Beaufort Sea area and lowest in (western and southern) Hudson Bay area and Chukchi/Bering Sea. In contrast, concentrations of Cd showed an increasing trend from east to west. Minor or no spatial trends were observed for Cu, Mn, Rb and Zn. Spatial trends were in agreement with previous studies, possibly explained by natural phenomena. To assess