51
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Hauser DDW, Laidre KL, Stern HL, Suydam RS, Richard PR. Indirect effects of sea ice loss on summer‐fall habitat and behaviour for sympatric populations of an Arctic marine predator. DIVERS DISTRIB 2018. [DOI: 10.1111/ddi.12722] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Donna D. W. Hauser
- School of Aquatic & Fishery Sciences University of Washington Seattle WA USA
- Polar Science Center Applied Physics Laboratory University of Washington Seattle WA USA
| | - Kristin L. Laidre
- School of Aquatic & Fishery Sciences University of Washington Seattle WA USA
- Polar Science Center Applied Physics Laboratory University of Washington Seattle WA USA
| | - Harry L. Stern
- Polar Science Center Applied Physics Laboratory University of Washington Seattle WA USA
| | - Robert S. Suydam
- Department of Wildlife Management North Slope Borough Barrow AK USA
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52
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Rode KD, Olson J, Eggett D, Douglas DC, Durner GM, Atwood TC, Regehr EV, Wilson RR, Smith T, St. Martin M. Den phenology and reproductive success of polar bears in a changing climate. J Mammal 2018. [DOI: 10.1093/jmammal/gyx181] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Jay Olson
- Brigham Young University, Plant and Wildlife Sciences, Provo, UT, USA
| | - Dennis Eggett
- Center for Collaborative Research and Statistical Consulting, Department of Statistics, Brigham Young University, Provo, UT, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Tom Smith
- Brigham Young University, Plant and Wildlife Sciences, Provo, UT, USA
| | - Michelle St. Martin
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
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53
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Rode KD, Wilson RR, Douglas DC, Muhlenbruch V, Atwood TC, Regehr EV, Richardson ES, Pilfold NW, Derocher AE, Durner GM, Stirling I, Amstrup SC, St Martin M, Pagano AM, Simac K. Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity. GLOBAL CHANGE BIOLOGY 2018; 24:410-423. [PMID: 28994242 DOI: 10.1111/gcb.13933] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 08/02/2017] [Indexed: 05/27/2023]
Abstract
The effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter-specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic-feeding ice-associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (≥7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983-1999 and 2000-2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic-level productivity in these marine ecosystems.
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Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | | | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Evan S Richardson
- Wildlife Research Division, Science and Technology Branch, Environment Canada, Edmonton, AB, Canada
| | - Nicholas W Pilfold
- Institute for Conservation Research, San Diego Zoo Global, Escondido, CA, USA
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Ian Stirling
- Wildlife Research Division, Science and Technology Branch, Environment Canada, Edmonton, AB, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Steven C Amstrup
- Polar Bears International, Bozeman, MT, USA
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Michelle St Martin
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Anthony M Pagano
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - Kristin Simac
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
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54
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Pavlova V, Nabe-Nielsen J, Dietz R, Sonne C, Grimm V. Allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination. Proc Biol Sci 2017; 283:rspb.2016.1883. [PMID: 27903868 DOI: 10.1098/rspb.2016.1883] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/02/2016] [Indexed: 11/12/2022] Open
Abstract
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.
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Affiliation(s)
- Viola Pavlova
- Biology Centre of the AS CR, v.v.i., Institute of Hydrobiology, Na Sádkách 7, České Budějovice 370 05, Czech Republic .,Arctic Research Centre, Aarhus University, C.F. Møllers Allé 8, Aarhus C 8000, Denmark.,Department of Bioscience, Aarhus University, Frederiksborgvej 399, Roskilde 4000, Denmark
| | - Jacob Nabe-Nielsen
- Arctic Research Centre, Aarhus University, C.F. Møllers Allé 8, Aarhus C 8000, Denmark.,Department of Bioscience, Aarhus University, Frederiksborgvej 399, Roskilde 4000, Denmark
| | - Rune Dietz
- Arctic Research Centre, Aarhus University, C.F. Møllers Allé 8, Aarhus C 8000, Denmark.,Department of Bioscience, Aarhus University, Frederiksborgvej 399, Roskilde 4000, Denmark
| | - Christian Sonne
- Arctic Research Centre, Aarhus University, C.F. Møllers Allé 8, Aarhus C 8000, Denmark.,Department of Bioscience, Aarhus University, Frederiksborgvej 399, Roskilde 4000, Denmark
| | - Volker Grimm
- Department of Ecological Modelling, Helmholtz Center for Environmental Research-UFZ, Permoserstraße 15, Leipzig 04318, Germany
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55
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Wilson RR, Regehr EV, Rode KD, St Martin M. Invariant polar bear habitat selection during a period of sea ice loss. Proc Biol Sci 2017; 283:rspb.2016.0380. [PMID: 27534959 DOI: 10.1098/rspb.2016.0380] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 07/26/2016] [Indexed: 11/12/2022] Open
Abstract
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.
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Affiliation(s)
- Ryan R Wilson
- US Fish and Wildlife Service, 1011 E Tudor Road, Anchorage, AK 99503, USA
| | - Eric V Regehr
- US Fish and Wildlife Service, 1011 E Tudor Road, Anchorage, AK 99503, USA
| | - Karyn D Rode
- US Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Michelle St Martin
- US Fish and Wildlife Service, 1011 E Tudor Road, Anchorage, AK 99503, USA
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56
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Multiple-stressor effects in an apex predator: combined influence of pollutants and sea ice decline on lipid metabolism in polar bears. Sci Rep 2017; 7:16487. [PMID: 29184161 PMCID: PMC5705648 DOI: 10.1038/s41598-017-16820-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 11/17/2017] [Indexed: 12/14/2022] Open
Abstract
There is growing evidence from experimental and human epidemiological studies that many pollutants can disrupt lipid metabolism. In Arctic wildlife, the occurrence of such compounds could have serious consequences for seasonal feeders. We set out to study whether organohalogenated compounds (OHCs) could cause disruption of energy metabolism in female polar bears (Ursus maritimus) from Svalbard, Norway (n = 112). We analyzed biomarkers of energy metabolism including the abundance profiles of nine lipid-related genes, fatty acid (FA) synthesis and elongation indices in adipose tissue, and concentrations of lipid-related variables in plasma (cholesterol, high-density lipoprotein, triglycerides). Furthermore, the plasma metabolome and lipidome were characterized by low molecular weight metabolites and lipid fingerprinting, respectively. Polychlorinated biphenyls, chlordanes, brominated diphenyl ethers and perfluoroalkyl substances were significantly related to biomarkers involved in lipid accumulation, FA metabolism, insulin utilization, and cholesterol homeostasis. Moreover, the effects of pollutants were measurable at the metabolome and lipidome levels. Our results indicate that several OHCs affect lipid biosynthesis and catabolism in female polar bears. Furthermore, these effects were more pronounced when combined with reduced sea ice extent and thickness, suggesting that climate-driven sea ice decline and OHCs have synergistic negative effects on polar bears.
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57
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Pagano AM, Rode KD, Atkinson SN. Evaluating methods to assess the body condition of female polar bears. URSUS 2017. [DOI: 10.2192/ursu-d-16-00029.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Anthony M. Pagano
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
- Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Karyn D. Rode
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
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58
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Durner GM, Douglas DC, Albeke SE, Whiteman JP, Amstrup SC, Richardson E, Wilson RR, Ben-David M. Increased Arctic sea ice drift alters adult female polar bear movements and energetics. GLOBAL CHANGE BIOLOGY 2017; 23:3460-3473. [PMID: 28586523 DOI: 10.1111/gcb.13746] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 03/17/2017] [Accepted: 04/13/2017] [Indexed: 06/07/2023]
Abstract
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.
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Affiliation(s)
- George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA
| | - David C Douglas
- U.S. Geological Survey, Alaska Science Center, Juneau, AK, USA
| | - Shannon E Albeke
- Wyoming Geographic Information Science Center, University of Wyoming, Laramie, WY, USA
| | - John P Whiteman
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | | | - Evan Richardson
- Environment and Climate Change Canada, University of Alberta, Edmonton, AB, Canada
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Merav Ben-David
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
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59
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Bromaghin JF, Budge SM, Thiemann GW. Detect and exploit hidden structure in fatty acid signature data. Ecosphere 2017. [DOI: 10.1002/ecs2.1896] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Jeffrey F. Bromaghin
- Alaska Science Center; U.S. Geological Survey; 4210 University Drive Anchorage Alaska 99508 USA
| | - Suzanne M. Budge
- Process Engineering and Applied Science; Dalhousie University; Halifax Nova Scotia B3H 4R2 Canada
| | - Gregory W. Thiemann
- Faculty of Environmental Studies; York University; 4700 Keele Street Toronto Ontario M3J 1P3 Canada
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60
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McKinney MA, Atwood TC, Pedro S, Peacock E. Ecological Change Drives a Decline in Mercury Concentrations in Southern Beaufort Sea Polar Bears. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:7814-7822. [PMID: 28612610 DOI: 10.1021/acs.est.7b00812] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
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.
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Affiliation(s)
- Melissa A McKinney
- Wildlife and Fisheries Conservation Center, Department of Natural Resources and the Environment and Center for Environmental Sciences and Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Todd C Atwood
- United States Geological Survey, Alaska Science Center , Anchorage, Alaska 99508, United States
| | - Sara Pedro
- Wildlife and Fisheries Conservation Center, Department of Natural Resources and the Environment and Center for Environmental Sciences and Engineering, University of Connecticut , Storrs, Connecticut 06269, United States
| | - Elizabeth Peacock
- United States Geological Survey, Alaska Science Center , Anchorage, Alaska 99508, United States
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61
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Identifying shifts in maternity den phenology and habitat characteristics of polar bears (Ursus maritimus) in Baffin Bay and Kane Basin. Polar Biol 2017. [DOI: 10.1007/s00300-017-2172-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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62
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Bromaghin JF, Budge SM, Thiemann GW, Rode KD. Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data. Ecol Evol 2017; 7:6103-6113. [PMID: 28861216 PMCID: PMC5574754 DOI: 10.1002/ece3.3179] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/05/2017] [Accepted: 05/26/2017] [Indexed: 11/08/2022] Open
Abstract
Knowledge of animal diets provides essential insights into their life history and ecology, although diet estimation is challenging and remains an active area of research. Quantitative fatty acid signature analysis (QFASA) has become a popular method of estimating diet composition, especially for marine species. A primary assumption of QFASA is that constants called calibration coefficients, which account for the differential metabolism of individual fatty acids, are known. In practice, however, calibration coefficients are not known, but rather have been estimated in feeding trials with captive animals of a limited number of model species. The impossibility of verifying the accuracy of feeding trial derived calibration coefficients to estimate the diets of wild animals is a foundational problem with QFASA that has generated considerable criticism. We present a new model that allows simultaneous estimation of diet composition and calibration coefficients based only on fatty acid signature samples from wild predators and potential prey. Our model performed almost flawlessly in four tests with constructed examples, estimating both diet proportions and calibration coefficients with essentially no error. We also applied the model to data from Chukchi Sea polar bears, obtaining diet estimates that were more diverse than estimates conditioned on feeding trial calibration coefficients. Our model avoids bias in diet estimates caused by conditioning on inaccurate calibration coefficients, invalidates the primary criticism of QFASA, eliminates the need to conduct feeding trials solely for diet estimation, and consequently expands the utility of fatty acid data to investigate aspects of ecology linked to animal diets.
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Affiliation(s)
| | - Suzanne M Budge
- Process Engineering and Applied Science Dalhousie University Halifax NS Canada
| | | | - Karyn D Rode
- Alaska Science Center U.S. Geological Survey Anchorage AK USA
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63
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Hauser DDW, Laidre KL, Stafford KM, Stern HL, Suydam RS, Richard PR. Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation. GLOBAL CHANGE BIOLOGY 2017; 23:2206-2217. [PMID: 28001336 DOI: 10.1111/gcb.13564] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 10/20/2016] [Accepted: 11/07/2016] [Indexed: 05/08/2023]
Abstract
Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993-2002) and 'late' (2004-2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr-1 ) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how belugas may fare in the future.
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Affiliation(s)
- Donna D W Hauser
- School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98105, USA
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA
| | - Kristin L Laidre
- School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98105, USA
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA
| | - Kathleen M Stafford
- Applied Physics Laboratory, University of Washington, Seattle, WA, 98105, USA
| | - Harry L Stern
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA
| | - Robert S Suydam
- North Slope Borough, Department of Wildlife Management, PO Box 69, Barrow, AK, 99723, USA
| | - Pierre R Richard
- Freshwater Institute, Fisheries & Oceans Canada, 501 University Crescent, Winnipeg, MB, R3T 2N6, Canada
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64
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Hamilton CD, Kovacs KM, Ims RA, Aars J, Lydersen C. An Arctic predator-prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals. J Anim Ecol 2017; 86:1054-1064. [PMID: 28415134 DOI: 10.1111/1365-2656.12685] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 04/06/2017] [Indexed: 01/30/2023]
Abstract
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 interactions are likely to become more widespread in many ecosystems as both predators and prey respond to changing environmental conditions induced by global warming, highlighting the importance of multi-species studies.
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Affiliation(s)
- Charmain D Hamilton
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway.,Department of Arctic and Marine Biology, Arctic University of Norway, Tromsø, Norway
| | - Kit M Kovacs
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
| | - Rolf A Ims
- Department of Arctic and Marine Biology, Arctic University of Norway, Tromsø, Norway
| | - Jon Aars
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
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65
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Knott KK, Mastromonaco GF, Owen MA, Kouba AJ. Urinary profiles of progestin and androgen metabolites in female polar bears during parturient and non-parturient cycles. CONSERVATION PHYSIOLOGY 2017; 5:cox023. [PMID: 28458884 PMCID: PMC5402292 DOI: 10.1093/conphys/cox023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 03/21/2017] [Accepted: 04/11/2017] [Indexed: 06/07/2023]
Abstract
Due to the environmental and anthropogenic impacts that continue to threaten the reproductive success of polar bears, a more detailed understanding of their reproductive cycle is needed. Captive populations of polar bears provide an excellent opportunity to learn more about the reproductive physiology of the species. Progestin (P4) and androgen (T) metabolites in urine, and their ratio (P4:T), were examined during 11 reproductive cycles of captive female polar bears (n = 4) to characterize the steroid hormone profile during pregnancy and determine possible variations related to reproductive failure. The concentration of hormone metabolites in urine were determined through enzyme immunoassay. Reproductive cycles were classified as pregnant (n = 3), anovulatory (n = 4) and ovulatory-non-parturient (n = 4) based on the changes in urinary hormone metabolite values and cub production. In the absence of a lactational suppression of estrus, elevated androgen concentrations suggested resumption of follicular development within 3 weeks of parturition. Breeding behaviours were most often observed when androgen values were at their highest or in decline. Ovulation was identified by a return to basal androgen concentration and elevation of progestins within 1-4 weeks after breeding. As a result, urinary concentrations of progestins were greater than androgens (P4:T ratio ≥ 1.0) during ovulatory cycles whereas the P4:T ratio was <1.0 when females were anovulatory. Progestins and the P4:T ratio of parturient cycles were greatest beginning in June/July (17-20 weeks after breeding) and reached a peak at 24-37 weeks (mid-October/mid-November, 4-9 weeks before birth of cubs). Non-invasive monitoring of hormone metabolites in urine provided a rapid determination of endocrine function for improved husbandry and reproductive management of polar bears in captivity. Further research is warranted to understand the reproductive endocrinology of polar bears and its impact on conservation and management of this species in captivity and the wild.
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Affiliation(s)
- Katrina K. Knott
- Conservation and Research Department, Memphis Zoo, 2000 Prentiss Place, Memphis, TN 38112,USA
| | | | - Megan A. Owen
- Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, CA 92027,USA
| | - Andrew J. Kouba
- Conservation and Research Department, Memphis Zoo, 2000 Prentiss Place, Memphis, TN 38112,USA
- Department of Wildlife, Fisheries and Aquaculture, A205 Thompson Hall, Box 9690, Mississippi State University, MS 39762,USA
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66
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Regehr EV, Wilson RR, Rode KD, Runge MC, Stern HL. Harvesting wildlife affected by climate change: a modelling and management approach for polar bears. J Appl Ecol 2017; 54:1534-1543. [PMID: 29081540 PMCID: PMC5637955 DOI: 10.1111/1365-2664.12864] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2016] [Accepted: 12/22/2016] [Indexed: 11/29/2022]
Abstract
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 goals. In our example application to polar bears experiencing sea-ice loss, the goals are to maintain population viability while providing continued opportunities for subsistence harvest. Our approach may be relevant to other species for which near-term management is focused on human factors that directly influence population dynamics within the broader context of climate-induced habitat degradation.
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Affiliation(s)
- Eric V Regehr
- U.S. Fish and Wildlife Service Anchorage AK USA.,Present address: University of Washington Seattle WA USA
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67
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Ware JV, Rode KD, Bromaghin JF, Douglas DC, Wilson RR, Regehr EV, Amstrup SC, Durner GM, Pagano AM, Olson J, Robbins CT, Jansen HT. Habitat degradation affects the summer activity of polar bears. Oecologia 2017; 184:87-99. [PMID: 28247129 DOI: 10.1007/s00442-017-3839-y] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 02/09/2017] [Indexed: 01/24/2023]
Abstract
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.
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Affiliation(s)
- Jasmine V Ware
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA.
| | - Karyn D Rode
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Jeffrey F Bromaghin
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - David C Douglas
- Alaska Science Center, U.S. Geological Survey, 250 Egan Drive, Juneau, AK, 99801, USA
| | - Ryan R Wilson
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, MS 341, Anchorage, AK, 99503, USA
| | | | - George M Durner
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Anthony M Pagano
- Alaska Science Center, U.S. Geological Survey, 4210 University Dr., Anchorage, AK, 99508, USA
| | - Jay Olson
- Department of Plant and Wildlife Sciences, Brigham Young University, 5049 LSB, Provo, UT, 84602, USA
| | - Charles T Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA
| | - Heiko T Jansen
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, 99164-7620, USA
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68
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Hauser DDW, Laidre KL, Stern HL, Moore SE, Suydam RS, Richard PR. Habitat selection by two beluga whale populations in the Chukchi and Beaufort seas. PLoS One 2017; 12:e0172755. [PMID: 28235041 PMCID: PMC5325469 DOI: 10.1371/journal.pone.0172755] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 02/09/2017] [Indexed: 11/18/2022] Open
Abstract
There has been extensive sea ice loss in the Chukchi and Beaufort seas where two beluga whale (Delphinapterus leucas) populations occur between July-November. Our goal was to develop population-specific beluga habitat selection models that quantify relative use of sea ice and bathymetric features related to oceanographic processes, which can provide context to the importance of changing sea ice conditions. We established habitat selection models that incorporated daily sea ice measures (sea ice concentration, proximity to ice edge and dense ice) and bathymetric features (slope, depth, proximity to the continental slope, Barrow Canyon, and shore) to establish quantitative estimates of habitat use for the Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') populations. We applied 'used v. available' resource selection functions to locations of 65 whales tagged from 1993-2012, revealing large variations in seasonal habitat selection that were distinct between sex and population groups. Chukchi whales of both sexes were predicted to use areas in close proximity to Barrow Canyon (typically <200 km) as well as the continental slope in summer, although deeper water and denser ice were stronger predictors for males than females. Habitat selection differed more between sexes for Beaufort belugas. Beaufort males selected higher ice concentrations (≥40%) than females (0-40%) in July-August. Proximity to shore (<200 km) strongly predicted summer habitat of Beaufort females, while distance to the ice edge was important for male habitat selection, especially during westward migration in September. Overall, our results indicate that sea ice variables were rarely the primary drivers of beluga summer-fall habitat selection. While diminished sea ice may indirectly affect belugas through changes in the ecosystem, associations with bathymetric features that affect prey availability seemed key to habitat selection during summer and fall. These results provide a benchmark by which to assess future changes in beluga habitat use of the Pacific Arctic.
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Affiliation(s)
- Donna D. W. Hauser
- School of Aquatic & Fishery Sciences, University of Washington, Seattle, WA, United States of America
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, United States of America
- * E-mail:
| | - Kristin L. Laidre
- School of Aquatic & Fishery Sciences, University of Washington, Seattle, WA, United States of America
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, United States of America
| | - Harry L. Stern
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, United States of America
| | - Sue E. Moore
- Office of Science & Technology, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way NE, Seattle, WA, United States of America
| | - Robert S. Suydam
- North Slope Borough, Department of Wildlife Management, Barrow, AK, United States of America
| | - Pierre R. Richard
- Freshwater Institute, Fisheries & Oceans Canada, 501 University Crescent, Winnipeg, Canada
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69
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Affiliation(s)
- Jeffrey F. Bromaghin
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage AK 99508 USA
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70
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Implications of Rapid Environmental Change for Polar Bear Behavior and Sociality. MARINE MAMMAL WELFARE 2017. [DOI: 10.1007/978-3-319-46994-2_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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71
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Regehr EV, Laidre KL, Akçakaya HR, Amstrup SC, Atwood TC, Lunn NJ, Obbard M, Stern H, Thiemann GW, Wiig Ø. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biol Lett 2016; 12:20160556. [PMID: 27928000 PMCID: PMC5206583 DOI: 10.1098/rsbl.2016.0556] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/21/2016] [Indexed: 11/12/2022] Open
Abstract
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.
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Affiliation(s)
- Eric V Regehr
- Marine Mammals Management, US Fish and Wildlife Service, Anchorage, AK 99503, USA
| | - Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - H Resit Akçakaya
- Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY 11794, USA
| | | | - Todd C Atwood
- Alaska Science Center, US Geological Survey, Anchorage, AK 99508, USA
| | - Nicholas J Lunn
- Environment and Climate Change Canada, Edmonton, Alberta, Canada T6G 2E9
| | - Martyn Obbard
- Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario, Canada K9J 7B8
| | - Harry Stern
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA 98105, USA
| | - Gregory W Thiemann
- Faculty of Environmental Studies, York University, Toronto, Ontario, Canada M3J 1P3
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Oslo 0318, Norway
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72
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Nuijten RJM, Hendriks AJ, Jenssen BM, Schipper AM. Circumpolar contaminant concentrations in polar bears (Ursus maritimus) and potential population-level effects. ENVIRONMENTAL RESEARCH 2016; 151:50-57. [PMID: 27450999 DOI: 10.1016/j.envres.2016.07.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/08/2016] [Accepted: 07/15/2016] [Indexed: 06/06/2023]
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 bio-accumulate and bio-magnify in the food chain, leading to high concentrations at the level of top-predators. In Arctic wildlife, including the polar bear, various adverse health effects have been related to internal concentrations of commercially used anthropogenic chemicals like PCB and DDT. The extent to which these individual health effects are associated to population-level effects is, however, unknown. In this study we assembled data on adipose tissue concentrations of ∑PCB, ∑DDT, dieldrin and ∑PBDE in individual polar bears from peer-reviewed scientific literature. Data were available for 14 out of the 19 subpopulations. We found that internal concentrations of these contaminants exceed threshold values for adverse individual health effects in several subpopulations. In an exploratory regression analysis we identified a clear negative correlation between polar bear population density and sub-population specific contaminant concentrations in adipose tissue. The results suggest that adverse health effects of contaminants in individual polar bears may scale up to population-level consequences. Our study highlights the need to consider contaminant exposure along with other threats in polar bear population viability analyses.
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Affiliation(s)
- R J M Nuijten
- Department of Environmental Science, Institute for Water and Wetland Research (IWWR), Radboud University (RU), NL-6500 GL Nijmegen, The Netherlands; Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), 7608 PB Wageningen, The Netherlands.
| | - A J Hendriks
- Department of Environmental Science, Institute for Water and Wetland Research (IWWR), Radboud University (RU), NL-6500 GL Nijmegen, The Netherlands
| | - B M Jenssen
- Department of Biology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway; Department of Arctic Technology, The University Centre in Svalbard, Longyearbyen, Norway
| | - A M Schipper
- Department of Environmental Science, Institute for Water and Wetland Research (IWWR), Radboud University (RU), NL-6500 GL Nijmegen, The Netherlands; PBL Netherlands Environmental Assessment Agency, PO Box 303, 3720 AH Bilthoven, The Netherlands
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73
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Galicia MP, Thiemann GW, Dyck MG, Ferguson SH, Higdon JW. Dietary habits of polar bears in Foxe Basin, Canada: possible evidence of a trophic regime shift mediated by a new top predator. Ecol Evol 2016; 6:6005-18. [PMID: 27547372 PMCID: PMC4983609 DOI: 10.1002/ece3.2173] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 04/05/2016] [Accepted: 04/13/2016] [Indexed: 11/09/2022] Open
Abstract
Polar bear (Ursus maritimus) subpopulations in several areas with seasonal sea ice regimes have shown declines in body condition, reproductive rates, or abundance as a result of declining sea ice habitat. In the Foxe Basin region of Nunavut, Canada, the size of the polar bear subpopulation has remained largely stable over the past 20 years, despite concurrent declines in sea ice habitat. We used fatty acid analysis to examine polar bear feeding habits in Foxe Basin and thus potentially identify ecological factors contributing to population stability. Adipose tissue samples were collected from 103 polar bears harvested during 2010-2012. Polar bear diet composition varied spatially within the region with ringed seal (Pusa hispida) comprising the primary prey in northern and southern Foxe Basin, whereas polar bears in Hudson Strait consumed equal proportions of ringed seal and harp seal (Pagophilus groenlandicus). Walrus (Odobenus rosmarus) consumption was highest in northern Foxe Basin, a trend driven by the ability of adult male bears to capture large-bodied prey. Importantly, bowhead whale (Balaena mysticetus) contributed to polar bear diets in all areas and all age and sex classes. Bowhead carcasses resulting from killer whale (Orcinus orca) predation and subsistence harvest potentially provide an important supplementary food source for polar bears during the ice-free period. Our results suggest that the increasing abundance of killer whales and bowhead whales in the region could be indirectly contributing to improved polar bear foraging success despite declining sea ice habitat. However, this indirect interaction between top predators may be temporary if continued sea ice declines eventually severely limit on-ice feeding opportunities for polar bears.
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Affiliation(s)
- Melissa P Galicia
- Department of Biology York University Toronto Ontario M3J 1P3 Canada
| | - Gregory W Thiemann
- Faculty of Environmental Studies York University Toronto Ontario M3J 1P3 Canada
| | - Markus G Dyck
- Wildlife Research Section Department of Environment Government of Nunavut P.O. Box 209 Igloolik Nunavut X0A 0L0 Canada
| | - Steven H Ferguson
- Fisheries and Oceans Canada 501 University Crescent Winnipeg Manitoba R3T 2N6 Canada
| | - Jeff W Higdon
- Higdon Wildlife Consulting 912 Ashburn Street Winnipeg Manitoba R3G 3C9 Canada
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74
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Lunn NJ, Servanty S, Regehr EV, Converse SJ, Richardson E, Stirling I. Demography of an apex predator at the edge of its range: impacts of changing sea ice on polar bears in Hudson Bay. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:1302-1320. [PMID: 27755745 DOI: 10.1890/15-1256] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 11/30/2015] [Accepted: 12/01/2015] [Indexed: 05/25/2023]
Abstract
Changes in the abundance and distribution of wildlife populations are common consequences of historic and contemporary climate change. Some Arctic marine mammals, such as the polar bear (Ursus maritimus), may be particularly vulnerable to such changes due to the loss of Arctic sea ice. We evaluated the impacts of environmental variation on demographic rates for the Western Hudson Bay (WH), polar bear subpopulation from 1984 to 2011 using live-recapture and dead-recovery data in a Bayesian implementation of multistate capture-recapture models. We found that survival of female polar bears was related to the annual timing of sea ice break-up and formation. Using estimated vital rates (e.g., survival and reproduction) in matrix projection models, we calculated the growth rate of the WH subpopulation and projected population responses under different environmental scenarios while accounting for parametric uncertainty, temporal variation, and demographic stochasticity. Our analysis suggested a long-term decline in the number of bears from 1185 (95% Bayesian credible interval [BCI] = 993-1411) in 1987 to 806 (95% BCI = 653-984) in 2011. In the last 10 yr of the study, the number of bears appeared stable due to temporary stability in sea ice conditions (mean population growth rate for the period 2001-2010 = 1.02, 95% BCI = 0.98-1.06). Looking forward, we estimated long-term growth rates for the WH subpopulation of ~1.02 (95% BCI = 1.00-1.05) and 0.97 (95% BCI = 0.92-1.01) under hypothetical high and low sea ice conditions, respectively. Our findings support previous evidence for a demographic linkage between sea ice conditions and polar bear population dynamics. Furthermore, we present a robust framework for sensitivity analysis with respect to continued climate change (e.g., to inform scenario planning) and for evaluating the combined effects of climate change and management actions on the status of wildlife populations.
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Affiliation(s)
- Nicholas J Lunn
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Sabrina Servanty
- Colorado Cooperative Fish and Wildlife Research Unit, Colorado State University, Fort Collins, Colorado, 80523, USA
- Patuxent Wildlife Research Center, US Geological Survey, 12100 Beech Forest Road, Laurel, Maryland, 20708, USA
| | - Eric V Regehr
- Marine Mammals Management, US Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, Alaska, 99503, USA
| | - Sarah J Converse
- Patuxent Wildlife Research Center, US Geological Survey, 12100 Beech Forest Road, Laurel, Maryland, 20708, USA
| | - Evan Richardson
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
| | - Ian Stirling
- Wildlife Research Division, Science & Technology Branch, Environment and Climate Change Canada, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, T6G 2E9, Canada
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75
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Atwood TC, Marcot BG, Douglas DC, Amstrup SC, Rode KD, Durner GM, Bromaghin JF. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 2016. [DOI: 10.1002/ecs2.1370] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Todd C. Atwood
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - Bruce G. Marcot
- Pacific Northwest Research StationU.S.D.A. Forest Service Portland Oregon 97208 USA
| | - David C. Douglas
- Alaska Science CenterU.S. Geological Survey Juneau Alaska 99801 USA
| | | | - Karyn D. Rode
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - George M. Durner
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
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76
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Sciullo L, Thiemann GW, Lunn NJ. Comparative assessment of metrics for monitoring the body condition of polar bears in western Hudson Bay. J Zool (1987) 2016. [DOI: 10.1111/jzo.12354] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L. Sciullo
- Department of Biology; York University; Toronto Ontario M3J 1P3 Canada
| | - G. W. Thiemann
- Faculty of Environmental Studies; York University; Toronto Ontario M3J 1P3 Canada
| | - N. J. Lunn
- Wildlife Research Division; Science and Technology Branch; Environment and Climate Change Canada; University of Alberta; Edmonton Alberta T6G 2E9 Canada
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Tartu S, Bourgeon S, Aars J, Andersen M, Ehrich D, Thiemann GW, Welker JM, Routti H. Geographical Area and Life History Traits Influence Diet in an Arctic Marine Predator. PLoS One 2016; 11:e0155980. [PMID: 27196700 PMCID: PMC4873193 DOI: 10.1371/journal.pone.0155980] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 05/06/2016] [Indexed: 11/22/2022] Open
Abstract
Global changes are thought to affect most Arctic species, yet some populations are more at risk. Today, the Barents Sea ecoregion is suffering the strongest sea ice retreat ever measured; and these changes are suspected to modify food access and thus diet of several species. Biochemical diet tracers enable investigation of diet in species such as polar bears (Ursus maritimus). We examined individual diet variation of female polar bears in Svalbard, Norway, and related it to year, season (spring and autumn), sampling area and breeding status (solitary, with cubs of the year or yearlings). Sampling areas were split according to their ice cover: North-West (less sea ice cover), South-East (larger amplitude in sea ice extent) and North-East/South-West (NESW) as bears from that zone are more mobile among all regions of Svalbard. We measured fatty acid (FA) composition in adipose tissue and carbon (δ13C) and nitrogen (δ15N) stable isotopes in plasma and red blood cells. Females feeding in the North-West area had lower δ15N values than those from the NESW. In South-East females, δ13C values were lower in autumn compared to spring and females seemed less selective in their diet as depicted by large variances in stable isotope values. Considering the differences in FA composition and stable isotope values, we suggest that females from the North-West and South-East could ingest a higher proportion of avian prey. With regard to breeding status, solitary females had higher δ15N values and smaller variance in their stable isotopic values than females with cubs, suggesting that solitary females were more selective and prey on higher trophic level species (i.e. seals). Overall, our results indicate that prey availability for Svalbard polar bears varies according to geographical area and prey selectivity differs according to breeding status. Our findings suggest that complex changes in sea ice and prey availability will interact to affect Svalbard polar bear feeding patterns and associated nutrition.
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Affiliation(s)
- Sabrina Tartu
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
- * E-mail:
| | - Sophie Bourgeon
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
- UiT-The Arctic University of Norway, Department of Arctic and Marine Biology, Tromsø, Norway
| | - Jon Aars
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
| | | | - Dorothee Ehrich
- UiT-The Arctic University of Norway, Department of Arctic and Marine Biology, Tromsø, Norway
| | | | - Jeffrey M. Welker
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, Alaska, United States of America
- University Center in Svalbard, Longyearbyen, Svalbard, Norway
| | - Heli Routti
- Norwegian Polar Institute, Fram Centre, Tromsø, Norway
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York J, Dowsley M, Cornwell A, Kuc M, Taylor M. Demographic and traditional knowledge perspectives on the current status of Canadian polar bear subpopulations. Ecol Evol 2016; 6:2897-924. [PMID: 27069588 PMCID: PMC4804000 DOI: 10.1002/ece3.2030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Revised: 01/21/2016] [Accepted: 01/23/2016] [Indexed: 11/05/2022] Open
Abstract
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 subpopulations should be continued and enhanced and that adaptive management practices are warranted.
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Affiliation(s)
- Jordan York
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
| | - Martha Dowsley
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
| | - Adam Cornwell
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
| | - Miroslaw Kuc
- Miroslaw Kuc PH 205-942 Yonge Street Toronto ON M4W 3S8 Canada
| | - Mitchell Taylor
- Department of Geography and the Environment Lakehead University 955 Oliver Road Thunder Bay ON P7B 5E1 Canada
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Rode KD, Wilson RR, Regehr EV, St. Martin M, Douglas DC, Olson J. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions. PLoS One 2015; 10:e0142213. [PMID: 26580809 PMCID: PMC4651550 DOI: 10.1371/journal.pone.0142213] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 10/19/2015] [Indexed: 11/21/2022] Open
Abstract
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.
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Affiliation(s)
- Karyn D. Rode
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, Alaska, 99508, United States of America
- * E-mail:
| | - Ryan R. Wilson
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - Eric V. Regehr
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - Michelle St. Martin
- United States Fish and Wildlife Service, Marine Mammals Management, 1011 E Tudor Road, Anchorage, Alaska, 99503, United States of America
| | - David C. Douglas
- U.S. Geological Survey, Alaska Science Center, 250 Egan Drive, Juneau, Alaska, 99801, United States of America
| | - Jay Olson
- Brigham Young University, Plant and Wildlife Sciences, 5049 LSB, Provo, Utah, 84602, United States of America
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Miller S, Wilder J, Wilson RR. Polar bear–grizzly bear interactions during the autumn open-water period in Alaska. J Mammal 2015. [DOI: 10.1093/jmammal/gyv140] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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84
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Bromaghin JF, Budge SM, Thiemann GW, Rode KD. Assessing the robustness of quantitative fatty acid signature analysis to assumption violations. Methods Ecol Evol 2015. [DOI: 10.1111/2041-210x.12456] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Jeffrey F. Bromaghin
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage Alaska 99508 USA
| | - Suzanne M. Budge
- Process Engineering and Applied Science Dalhousie University Halifax NS B3H 4R2 Canada
| | - Gregory W. Thiemann
- Faculty of Environmental Studies York University 4700 Keele St. Toronto ON M3J 1P3 Canada
| | - Karyn D. Rode
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage Alaska 99508 USA
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85
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Galicia MP, Thiemann GW, Dyck MG, Ferguson SH. Characterization of polar bear (Ursus maritimus) diets in the Canadian High Arctic. Polar Biol 2015. [DOI: 10.1007/s00300-015-1757-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Laidre KL, Stern H, Kovacs KM, Lowry L, Moore SE, Regehr EV, Ferguson SH, Wiig Ø, Boveng P, Angliss RP, Born EW, Litovka D, Quakenbush L, Lydersen C, Vongraven D, Ugarte F. Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2015; 29:724-37. [PMID: 25783745 PMCID: PMC5008214 DOI: 10.1111/cobi.12474] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Revised: 11/18/2014] [Accepted: 12/06/2014] [Indexed: 05/05/2023]
Abstract
Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also examined species diversity, the extent of human use, and temporal trends in sea ice habitat for 12 regions of the Arctic by calculating the dates of spring sea ice retreat and fall sea ice advance from satellite data (1979-2013). Estimates of AMM abundance varied greatly in quality, and few studies were long enough for trend analysis. Of the AMM subpopulations, 78% (61 of 78) are legally harvested for subsistence purposes. Changes in sea ice phenology have been profound. In all regions except the Bering Sea, the duration of the summer (i.e., reduced ice) period increased by 5-10 weeks and by >20 weeks in the Barents Sea between 1979 and 2013. In light of generally poor data, the importance of human use, and forecasted environmental changes in the 21st century, we recommend the following for effective AMM conservation: maintain and improve comanagement by local, federal, and international partners; recognize spatial and temporal variability in AMM subpopulation response to climate change; implement monitoring programs with clear goals; mitigate cumulative impacts of increased human activity; and recognize the limits of current protected species legislation.
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Affiliation(s)
- Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, 1013 NE 40th Street, University of Washington, Seattle, WA, 98105, U.S.A
- Greenland Institute of Natural Resources, P.O. Box 570, 3900, Nuuk, Greenland
| | - Harry Stern
- Polar Science Center, Applied Physics Laboratory, 1013 NE 40th Street, University of Washington, Seattle, WA, 98105, U.S.A
| | - Kit M Kovacs
- Norwegian Polar Institute, Fram Centre, N-9296, Tromsø, Norway
| | - Lloyd Lowry
- School of Fisheries and Ocean Sciences, University of Alaska, 73-4388, Paiaha Street, Kailua Kona, HI 96740, U.S.A
| | - Sue E Moore
- National Marine Fisheries Service, National Oceanographic and Atmospheric Administration, 7600 Sand Point Way NE, Seattle, WA, 98115, U.S.A
| | - Eric V Regehr
- U.S. Fish and Wildlife Service, 1011 East Tudor Road, Anchorage, AK, 99503, U.S.A
| | - Steven H Ferguson
- Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg, MB, R3T 2N6, Canada
| | - Øystein Wiig
- Natural History Museum, University of Oslo, P.O. Box 1172, Blindern, N-0318, Oslo, Norway
| | - Peter Boveng
- National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, 7600, Sand Point Way NE, Seattle, WA 98115, U.S.A
| | - Robyn P Angliss
- National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, 7600, Sand Point Way NE, Seattle, WA 98115, U.S.A
| | - Erik W Born
- Greenland Institute of Natural Resources, P.O. Box 570, 3900, Nuuk, Greenland
| | - Dennis Litovka
- ChukotTINRO, P.O. Box 29, Str. Otke, 56, Anadyr, Chukotka, 689000, Russia
| | - Lori Quakenbush
- Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK, 99701, U.S.A
| | | | - Dag Vongraven
- Norwegian Polar Institute, Fram Centre, N-9296, Tromsø, Norway
| | - Fernando Ugarte
- Greenland Institute of Natural Resources, P.O. Box 570, 3900, Nuuk, Greenland
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87
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Patyk KA, Duncan C, Nol P, Sonne C, Laidre K, Obbard M, Wiig Ø, Aars J, Regehr E, Gustafson LL, Atwood T. Establishing a definition of polar bear (Ursus maritimus) health: a guide to research and management activities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 514:371-378. [PMID: 25679818 DOI: 10.1016/j.scitotenv.2015.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 06/04/2023]
Abstract
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.
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Affiliation(s)
- Kelly A Patyk
- Center for Epidemiology and Animal Health, Science Technology and Analysis Services, Veterinary Services, Animal and Plant Health Inspection Service, U.S. Department of Agriculture, USA.
| | - Colleen Duncan
- Colorado State University Veterinary Diagnostic Laboratory, Colorado State University, USA
| | - Pauline Nol
- National Wildlife Research Center, Veterinary Services, Animal and Plant Health Inspection Service, U.S. Department of Agriculture, USA
| | - Christian Sonne
- Aarhus University, Faculty of Science and Technology, Department of Bioscience, Arctic Research Centre (ARC), Denmark
| | - Kristin Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, USA
| | - Martyn Obbard
- Wildlife Research and Monitoring Section, Ontario Ministry of Natural Resources and Forestry, Canada
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Norway
| | - Jon Aars
- Norwegian Polar Institute, Norway
| | - Eric Regehr
- U.S. Fish and Wildlife Service, Marine Mammals Management Program, USA
| | - Lori L Gustafson
- Center for Epidemiology and Animal Health, Science Technology and Analysis Services, Veterinary Services, Animal and Plant Health Inspection Service, U.S. Department of Agriculture, USA
| | - Todd Atwood
- U.S. Geological Survey, Alaska Science Center, USA.
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Rogers MC, Peacock E, Simac K, O’Dell MB, Welker JM. Diet of female polar bears in the southern Beaufort Sea of Alaska: evidence for an emerging alternative foraging strategy in response to environmental change. Polar Biol 2015. [DOI: 10.1007/s00300-015-1665-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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90
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Bromaghin JF, Rode KD, Budge SM, Thiemann GW. Distance measures and optimization spaces in quantitative fatty acid signature analysis. Ecol Evol 2015; 5:1249-62. [PMID: 25859330 PMCID: PMC4377268 DOI: 10.1002/ece3.1429] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 01/21/2015] [Accepted: 01/27/2015] [Indexed: 11/24/2022] Open
Abstract
Quantitative fatty acid signature analysis has become an important method of diet estimation in ecology, especially marine ecology. Controlled feeding trials to validate the method and estimate the calibration coefficients necessary to account for differential metabolism of individual fatty acids have been conducted with several species from diverse taxa. However, research into potential refinements of the estimation method has been limited. We compared the performance of the original method of estimating diet composition with that of five variants based on different combinations of distance measures and calibration-coefficient transformations between prey and predator fatty acid signature spaces. Fatty acid signatures of pseudopredators were constructed using known diet mixtures of two prey data sets previously used to estimate the diets of polar bears Ursus maritimus and gray seals Halichoerus grypus, and their diets were then estimated using all six variants. In addition, previously published diets of Chukchi Sea polar bears were re-estimated using all six methods. Our findings reveal that the selection of an estimation method can meaningfully influence estimates of diet composition. Among the pseudopredator results, which allowed evaluation of bias and precision, differences in estimator performance were rarely large, and no one estimator was universally preferred, although estimators based on the Aitchison distance measure tended to have modestly superior properties compared to estimators based on the Kullback–Leibler distance measure. However, greater differences were observed among estimated polar bear diets, most likely due to differential estimator sensitivity to assumption violations. Our results, particularly the polar bear example, suggest that additional research into estimator performance and model diagnostics is warranted.
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Affiliation(s)
- Jeffrey F Bromaghin
- U.S. Geological Survey, Alaska Science Center 4210 University Drive, Anchorage, Alaska, 99508
| | - Karyn D Rode
- U.S. Geological Survey, Alaska Science Center 4210 University Drive, Anchorage, Alaska, 99508
| | - Suzanne M Budge
- Process Engineering and Applied Science, Dalhousie University Halifax, Nova Scotia, B3H 4R2, Canada
| | - Gregory W Thiemann
- Faculty of Environmental Studies, York University 4700 Keele St., Toronto, Ontario, M3J 1P3, Canada
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91
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Peacock E, Sonsthagen SA, Obbard ME, Boltunov A, Regehr EV, Ovsyanikov N, Aars J, Atkinson SN, Sage GK, Hope AG, Zeyl E, Bachmann L, Ehrich D, Scribner KT, Amstrup SC, Belikov S, Born EW, Derocher AE, Stirling I, Taylor MK, Wiig Ø, Paetkau D, Talbot SL. Implications of the circumpolar genetic structure of polar bears for their conservation in a rapidly warming Arctic. PLoS One 2015; 10:e112021. [PMID: 25562525 PMCID: PMC4285400 DOI: 10.1371/journal.pone.0112021] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 09/19/2014] [Indexed: 11/18/2022] Open
Abstract
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 polar nations to proactively adjust conservation actions to continuing decline in sea-ice habitat.
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Affiliation(s)
- Elizabeth Peacock
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
- Department of Environment, Government of Nunavut, Igloolik, Nunavut, Canada
- * E-mail:
| | - Sarah A. Sonsthagen
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
| | - Martyn E. Obbard
- Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario, Canada
| | - Andrei Boltunov
- All-Russian Research Institute for Nature Protection, Moscow, Russian Federation
| | - Eric V. Regehr
- US Fish and Wildlife Service, Marine Mammals Management, Anchorage, Alaska, United States of America
| | | | - Jon Aars
- Norwegian Polar Institute, Tromsø, Norway
| | | | - George K. Sage
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
| | - Andrew G. Hope
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
| | - Eve Zeyl
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Lutz Bachmann
- Natural History Museum, University of Oslo, Oslo, Norway
| | | | - Kim T. Scribner
- Department of Zoology, Michigan State University, East Lansing, Michigan, United States of America
| | - Steven C. Amstrup
- Polar Bears International, Bozeman, Montana, United States of America
| | - Stanislav Belikov
- All-Russian Research Institute for Nature Protection, Moscow, Russian Federation
| | - Erik W. Born
- Greenland Institute of Natural Resources, Copenhagen, Denmark
| | - Andrew E. Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Ian Stirling
- Science & Technology Branch, Environment Canada, Edmonton, Alberta, Canada
| | - Mitchell K. Taylor
- Faculty of Science and Environmental Studies, Lakehead University, Thunder Bay, Ontario, Canada
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Oslo, Norway
| | - David Paetkau
- Wildlife Genetics International, Nelson, British Columbia, Canada
| | - Sandra L. Talbot
- Alaska Science Center, US Geological Survey, Anchorage, Alaska, United States of America
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92
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Projected polar bear sea ice habitat in the Canadian Arctic Archipelago. PLoS One 2014; 9:e113746. [PMID: 25426720 PMCID: PMC4245219 DOI: 10.1371/journal.pone.0113746] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/22/2014] [Indexed: 12/03/2022] Open
Abstract
Background 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. Principal Findings 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. Conclusions/Significance Under business-as-usual climate projections, polar bears may face starvation and reproductive failure across the entire Archipelago by the year 2100.
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93
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Wilson RR, Horne JS, Rode KD, Regehr EV, Durner GM. Identifying polar bear resource selection patterns to inform offshore development in a dynamic and changing Arctic. Ecosphere 2014. [DOI: 10.1890/es14-00193.1] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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