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Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century.

https://arctichealth.org/en/permalink/ahliterature270034
Source
Conserv Biol. 2015 Jun;29(3):724-37
Publication Type
Article
Date
Jun-2015
Author
Kristin L Laidre
Harry Stern
Kit M Kovacs
Lloyd Lowry
Sue E Moore
Eric V Regehr
Steven H Ferguson
Øystein Wiig
Peter Boveng
Robyn P Angliss
Erik W Born
Dennis Litovka
Lori Quakenbush
Christian Lydersen
Dag Vongraven
Fernando Ugarte
Source
Conserv Biol. 2015 Jun;29(3):724-37
Date
Jun-2015
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Cetacea - physiology
Climate change
Conservation of Natural Resources
Ecosystem
Ice Cover
Pinnipedia - physiology
Population Density
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.
PubMed ID
25783745 View in PubMed
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Climate change threatens polar bear populations: a stochastic demographic analysis.

https://arctichealth.org/en/permalink/ahliterature100110
Source
Ecology. 2010 Oct;91(10):2883-97
Publication Type
Article
Date
Oct-2010
Author
Christine M Hunter
Hal Caswell
Michael C Runge
Eric V Regehr
Steve C Amstrup
Ian Stirling
Author Affiliation
Department of Biology and Wildlife, Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska 99775, USA. christine.hunter@alaska.edu
Source
Ecology. 2010 Oct;91(10):2883-97
Date
Oct-2010
Language
English
Publication Type
Article
Keywords
Animals
Arctic Regions
Canada
Climate change
Ecosystem
Endangered Species
Models, Biological
Population Dynamics
Stochastic Processes
Time Factors
Uncertainty
United States
Ursidae - physiology
Abstract
The polar bear (Ursus maritimus) depends on sea ice for feeding, breeding, and movement. Significant reductions in Arctic sea ice are forecast to continue because of climate warming. We evaluated the impacts of climate change on polar bears in the southern Beaufort Sea by means of a demographic analysis, combining deterministic, stochastic, environment-dependent matrix population models with forecasts of future sea ice conditions from IPCC general circulation models (GCMs). The matrix population models classified individuals by age and breeding status; mothers and dependent cubs were treated as units. Parameter estimates were obtained from a capture-recapture study conducted from 2001 to 2006. Candidate statistical models allowed vital rates to vary with time and as functions of a sea ice covariate. Model averaging was used to produce the vital rate estimates, and a parametric bootstrap procedure was used to quantify model selection and parameter estimation uncertainty. Deterministic models projected population growth in years with more extensive ice coverage (2001-2003) and population decline in years with less ice coverage (2004-2005). LTRE (life table response experiment) analysis showed that the reduction in lambda in years with low sea ice was due primarily to reduced adult female survival, and secondarily to reduced breeding. A stochastic model with two environmental states, good and poor sea ice conditions, projected a declining stochastic growth rate, log lambdas, as the frequency of poor ice years increased. The observed frequency of poor ice years since 1979 would imply log lambdas approximately - 0.01, which agrees with available (albeit crude) observations of population size. The stochastic model was linked to a set of 10 GCMs compiled by the IPCC; the models were chosen for their ability to reproduce historical observations of sea ice and were forced with "business as usual" (A1B) greenhouse gas emissions. The resulting stochastic population projections showed drastic declines in the polar bear population by the end of the 21st century. These projections were instrumental in the decision to list the polar bear as a threatened species under the U.S. Endangered Species Act.
PubMed ID
21058549 View in PubMed
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Field metabolic rate and PCB adipose tissue deposition efficiency in East Greenland polar bears derived from contaminant monitoring data.

https://arctichealth.org/en/permalink/ahliterature262154
Source
PLoS One. 2014;9(8):e104037
Publication Type
Article
Date
2014
Author
Viola Pavlova
Jacob Nabe-Nielsen
Rune Dietz
Jens-Christian Svenning
Katrin Vorkamp
Frank Farsø Rigét
Christian Sonne
Robert J Letcher
Volker Grimm
Source
PLoS One. 2014;9(8):e104037
Date
2014
Language
English
Publication Type
Article
Keywords
Adipose Tissue - metabolism
Animals
Basal Metabolism
Climate change
Conservation of Natural Resources
Eating
Environmental monitoring
Feeding Behavior
Greenland
Models, Theoretical
Polychlorinated Biphenyls - analysis - chemistry - metabolism
Ursidae - metabolism - physiology
Abstract
Climate change will increasingly affect the natural habitat and diet of polar bears (Ursus maritimus). Understanding the energetic needs of polar bears is therefore important. We developed a theoretical method for estimating polar bear food consumption based on using the highly recalcitrant polychlorinated biphenyl (PCB) congener, 2,2',4,4',55-hexaCB (CB153) in bear adipose tissue as an indicator of food intake. By comparing the CB153 tissue concentrations in wild polar bears with estimates from a purposely designed individual-based model, we identified the possible combinations of field metabolic rates (FMR) and CB153 deposition efficiencies in East Greenland polar bears. Our simulations indicate that if 30% of the CB153 consumed by polar bear individuals were deposited into their adipose tissue, the corresponding FMR would be only two times the basal metabolic rate. In contrast, if the modelled CB153 deposition efficiency were 10%, adult polar bears would require six times more energy than that needed to cover basal metabolism. This is considerably higher than what has been assumed for polar bears in previous studies though it is similar to FMRs found in other marine mammals. An implication of this result is that even relatively small reductions in future feeding opportunities could impact the survival of East Greenland polar bears.
Notes
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PubMed ID
25101837 View in PubMed
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Heightened Immune System Function in Polar Bears Using Terrestrial Habitats.

https://arctichealth.org/en/permalink/ahliterature298349
Source
Physiol Biochem Zool. 2019 Jan/Feb; 92(1):1-11
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Author
John P Whiteman
Henry J Harlow
George M Durner
Eric V Regehr
Steven C Amstrup
Merav Ben-David
Source
Physiol Biochem Zool. 2019 Jan/Feb; 92(1):1-11
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Keywords
Adaptive Immunity
Alaska
Animals
Arctic Regions
Body Weight
C-Reactive Protein - analysis
Climate change
Ecosystem
Female
Ice Cover
Immunity, Innate
Leukocyte Count
Serum globulins
Ursidae - blood - immunology
Abstract
Climate change is altering the distribution of some wildlife species while warming temperatures are facilitating the northward expansion of pathogens, potentially increasing disease risk. Melting of Arctic sea ice is increasingly causing polar bears (Ursus maritimus) of the southern Beaufort Sea (SBS) to spend summer on land, where they may encounter novel pathogens. Here, we tested whether SBS polar bears on shore during summer exhibited greater immune system activity than bears remaining on the sea ice. In addition, we tested whether the type of immune response correlated with body condition, because adaptive responses (slowly developing defenses against specific pathogens) often require less energy than innate responses (rapid defenses not based on pathogen identity). After accounting for body condition, we found that polar bears on shore exhibited higher total white blood cell counts, neutrophils, and monocytes than bears on the ice, suggesting more infections. Lymphocytes, eosinophils, basophils, and globulins did not differ. C-reactive protein, an indicator of inflammation, also did not differ between habitats. Body condition was associated with variables indicative of both innate and adaptive immunity, suggesting that neither response was uniquely limited by energy resources. Our data indicate that as more polar bears spend longer periods of time on shore, they may experience more infections. We encourage continued health monitoring of this species and studies of the long-term fitness consequences from disease.
PubMed ID
30403916 View in PubMed
Less detail

Spring fasting behavior in a marine apex predator provides an index of ecosystem productivity.

https://arctichealth.org/en/permalink/ahliterature295310
Source
Glob Chang Biol. 2018 01; 24(1):410-423
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Date
01-2018
Author
Karyn D Rode
Ryan R Wilson
David C Douglas
Vanessa Muhlenbruch
Todd C Atwood
Eric V Regehr
Evan S Richardson
Nicholas W Pilfold
Andrew E Derocher
George M Durner
Ian Stirling
Steven C Amstrup
Michelle St Martin
Anthony M Pagano
Kristin Simac
Author Affiliation
U.S. Geological Survey, Alaska Science Center, Anchorage, AK, USA.
Source
Glob Chang Biol. 2018 01; 24(1):410-423
Date
01-2018
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.
Keywords
Animals
Arctic Regions
Caniformia
Climate change
Diet
Food chain
Ice Cover
Population Dynamics
Reproduction
Seasons
Ursidae - blood
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.
PubMed ID
28994242 View in PubMed
Less detail

6 records – page 1 of 1.