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range contraction and increasing isolation of a polar bear subpopulation in an era of sea-ice loss.climate change is expected to result in range shifts and habitat fragmentation for many species. in the arctic, loss of sea ice will reduce barriers to dispersal or eliminate movement corridors, resulting in increased connectivity or geographic isolation with sweeping implications for conservation. we used satellite telemetry, data from individually marked animals (research and harvest), and microsatellite genetic data to examine changes in geographic range, emigration, and interpopulation conne ...201829468025
a thermally insulating textile inspired by polar bear hair.animals living in the extremely cold environment, such as polar bears, have shown amazing capability to keep warm, benefiting from their hollow hairs. mimicking such a strategy in synthetic fibers would stimulate smart textiles for efficient personal thermal management, which plays an important role in preventing heat loss and improving efficiency in house warming energy consumption. here, a "freeze-spinning" technique is used to realize continuous and large-scale fabrication of fibers with alig ...201829443435
high-energy, high-fat lifestyle challenges an arctic apex predator, the polar bear.regional declines in polar bear (ursus maritimus) populations have been attributed to changing sea ice conditions, but with limited information on the causative mechanisms. by simultaneously measuring field metabolic rates, daily activity patterns, body condition, and foraging success of polar bears moving on the spring sea ice, we found that high metabolic rates (1.6 times greater than previously assumed) coupled with low intake of fat-rich marine mammal prey resulted in an energy deficit for m ...201829420288
choose your poison-space-use strategy influences pollutant exposure in barents sea polar bears.variation in space-use is common within mammal populations. in polar bears, ursus maritimus, some individuals follow the sea ice (offshore bears) whereas others remain nearshore yearlong (coastal bears). we studied pollutant exposure in relation to space-use patterns (offshore vs coastal) in adult female polar bears from the barents sea equipped with satellite collars (2000-2014, n = 152). first, we examined the differences in home range (hr) size and position, body condition, and diet proxies ( ...201829363970
high contributions of sea ice derived carbon in polar bear (ursus maritimus) tissue.polar bears (ursus maritimus) rely upon arctic sea ice as a physical habitat. consequently, conservation assessments of polar bears identify the ongoing reduction in sea ice to represent a significant threat to their survival. however, the additional role of sea ice as a potential, indirect, source of energy to bears has been overlooked. here we used the highly branched isoprenoid lipid biomarker-based index (h-print) approach in combination with quantitative fatty acid signature analysis to sho ...201829360849
optimal marine mammal welfare under human care: current efforts and future directions.marine mammals include cetaceans, pinnipeds, sirenians, sea otters and polar bears, many of which are charismatic and popular species commonly kept under human care in zoos and aquaria. however, in comparison with their fully terrestrial counterparts their welfare has been less intensively studied, and their partial or full reliance on the aquatic environment leads to unique welfare challenges. in this paper we attempt to collate and review the research undertaken thus far on marine mammal welfa ...201828927965
heritability of body size in the polar bears of western hudson bay.among polar bears (ursus maritimus), fitness is dependent on body size through males' abilities to win mates, females' abilities to provide for their young and all bears' abilities to survive increasingly longer fasting periods caused by climate change. in the western hudson bay subpopulation (near churchill, manitoba, canada), polar bears have declined in body size and condition, but nothing is known about the genetic underpinnings of body size variation, which may be subject to natural selecti ...201829667364
targeting acceptance in the management of food craving: the mediating roles of eating styles and thought suppression.food craving is now widely considered to be a cognitively motivated state. acceptance-based treatments are effective in reducing the adverse impact of food cravings on consumption, via a hypothesized decrease in experiential avoidance. the mechanisms that drive the success of acceptance-based management of craving remain to be empirically tested. this study examined the role of eating styles and thought suppression as mediators in the relationship between experiential avoidance and craving. part ...201829665461
corrigendum: internet blogs, polar bears, and climate-change denial by proxy.[this corrects the article doi: 10.1093/biosci/bix133.].201829664475
phenotypic plasticity and climate change: can polar bears respond to longer arctic summers with an adaptive fast?plasticity in the physiological and behavioural responses of animals to prolonged food shortages may determine the persistence of species under climate warming. this is particularly applicable for species that can "adaptively fast" by conserving protein to protect organ function while catabolizing endogenous tissues. some ursids, including polar bears (ursus maritimus), adaptively fast during winter hibernation-and it has been suggested that polar bears also employ this strategy during summer. w ...201829197040
potential impacts of offshore oil spills on polar bears in the chukchi sea.sea ice decline is anticipated to increase human access to the arctic ocean allowing for offshore oil and gas development in once inaccessible areas. given the potential negative consequences of an oil spill on marine wildlife populations in the arctic, it is important to understand the magnitude of impact a large spill could have on wildlife to inform response planning efforts. in this study we simulated oil spills that released 25,000 barrels of oil for 30 days in autumn originating from two s ...201829339335
organophosphate esters in east greenland polar bears and ringed seals: adipose tissue concentrations and in vitro depletion and metabolite formation.east greenland is a contamination "hot spot" for long-range transported anthropogenic chemicals, including organophosphate esters (opes). high concentrations of opes have been reported in arctic air while very little is known for wildlife where ope tissue residues levels appear to be strongly influenced by biotransformation. in the present study, the hepatic in vitro metabolism of six environmentally relevant organophosphate (op) triesters and corresponding op diester formation were investigated ...201829306196
the distribution and trends of persistent organic pollutants and mercury in marine mammals from canada's eastern arctic.arctic contaminant research in the marine environment has focused on organohalogen compounds and mercury mainly because they are bioaccumulative, persistent and toxic. this review summarizes and discusses the patterns and trends of persistent organic pollutants (pops) and mercury in ringed seals (pusa hispida) and polar bears (ursus maritimus) in the eastern canadian arctic relative to the rest of the canadian arctic. the review provides explanations for these trends and looks at the implication ...201829145101
survey for equine herpesviruses in polar bears ( ursus maritimus) and exotic equids housed in us aza institutions.infection by equine herpesvirus (ehv) strains (ehv-1, ehv-9) in ursid species, including polar bears ( ursus maritimus), has been associated with neurological disease and death. a serosurvey of captive exotic equid and polar bear populations in us association of zoos and aquaria institutions was performed to determine the prevalence of ehv strains using quantitative polymerase chain reaction (qpcr) and enzyme-linked immunosorbent assay (elisa) tests. equid species surveyed included zebra ( equus ...201830212313
spring fasting behavior in a marine apex predator provides an index of ecosystem productivity.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 con ...201828994242
discrimination factors of carbon and nitrogen stable isotopes from diet to hair in captive large arctic carnivores of conservation concern.stable isotope analysis is widely used to reconstruct diet, delineate trophic interactions, and determine energy pathways. such ecological inferences are based on the idea that animals are, isotopically, what they eat but with a predictable difference between the isotopic ratio of a consumer and that of its diet, coined as the discrimination factor. providing correct estimates of diet-consumer isotopic discrimination in controlled conditions is key for a robust application of the stable isotopes ...201830030922
hundreds of unrecognized halogenated contaminants discovered in polar bear serum.exposure of polar bears (ursus maritimus) to persistent organic pollutants was discovered in the 1970s, but recent evidence suggests the presence of unknown toxic chemicals in their blood. protein and phospholipid depleted serum was stirred with polyethersulfone capillaries to extract a broad range of analytes, and nontarget mass spectrometry with "fragmentation flagging" was used for detection. hundreds of analytes were discovered belonging to 13 classes, including novel polychlorinated bipheny ...201830376612
polar bears turn to whale meat as their hunting grounds melt. 201830327510
tracking arctic marine mammal resilience in an era of rapid ecosystem alteration.global warming is significantly altering arctic marine ecosystems. specifically, the precipitous loss of sea ice is creating a dichotomy between ice-dependent polar bears and pinnipeds that are losing habitat and some cetaceans that are gaining habitat. while final outcomes are hard to predict for the many and varied marine mammal populations that rely on arctic habitats, we suggest a simplified framework to assess status, based upon ranking a population's size, range, behavior, and health. this ...201830300350
effects of tanning on the stable isotopic compositions of hair.we investigated the effect of tanning on the stable isotopic compositions (cnhos) of hair keratin. samples of hair from polar bear (ursus maritimus) hides were collected before and after the tanning process from a commercial tannery. with the exception of sulphur isotopes, tanning did not alter the stable isotopic compositions of hair. δ34s values were slightly more positive (1 per mil) in hair that had gone through the tanning process, likely as a result of the tanning agent, alum (al2(so4)3) o ...201830286339
development of on-shore behavior among polar bears (ursus maritimus) in the southern beaufort sea: inherited or learned?polar bears (ursus maritimus) are experiencing rapid and substantial changes to their environment due to global climate change. polar bears of the southern beaufort sea (sb) have historically spent most of the year on the sea ice. however, recent reports from alaska indicate that the proportion of the sb subpopulation observed on-shore during late summer and early fall has increased. our objective was to investigate whether this on-shore behavior has developed through genetic inheritance, asocia ...201830250663
polar bear health in environmental science and translational medicine. 201830227316
metagenomic composition analysis of an ancient sequenced polar bear jawbone from svalbard.the sequencing of ancient dna samples provides a novel way to find, characterize, and distinguish exogenous genomes of endogenous targets. after sequencing, computational composition analysis enables filtering of undesired sources in the focal organism, with the purpose of improving the quality of assemblies and subsequent data analysis. more importantly, such analysis allows extinct and extant species to be identified without requiring a specific or new sequencing run. however, the identificati ...201830200636
thermodynamics of the hard-disk fluid at a planar hard wall: generalized scaled-particle theory and monte carlo simulation.a generalized scaled-particle theory for the uniform hard-disk mixture is derived in the spirit of the white bear ii free energy of the hard-sphere fluid [h. hansen-goos and r. roth, j. phys. c: condens. matter 18, 8413 (2006)]. the theory provides a very simple result for the interfacial free energy γ of the hard-disk fluid at a planar hard wall (which in d = 2 is a line) in terms of the equation of state. to complement and assess the theory, we perform monte carlo simulations from which we obt ...201830193513
evidence for ussurian tube-nosed bats (murina ussuriensis) hibernating in snow.surviving winter is a challenge for endothermic animals living at high latitudes. in bats, some species migrate to milder climates in winter, but others presumably stay and hibernate in thermally buffered roosts. however, we know little about where, or in what roosts bats hibernate. ussurian tube-nosed bats (murina ussuriensis) have occasionally been observed under or near the surface of snow. we collected the details of those accounts and used our own observations to conclude that these bats hi ...201830104736
the international mouse phenotyping consortium (impc): a functional catalogue of the mammalian genome that informs conservation.the international mouse phenotyping consortium (impc) is building a catalogue of mammalian gene function by producing and phenotyping a knockout mouse line for every protein-coding gene. to date, the impc has generated and characterised 5186 mutant lines. one-third of the lines have been found to be non-viable and over 300 new mouse models of human disease have been identified thus far. while current bioinformatics efforts are focused on translating results to better understand human disease pro ...201830100824
mean-field density functional theory of a nanoconfined classical, three-dimensional heisenberg fluid. ii. the interplay between molecular packing and orientational order.as in paper i of this series of papers [s. m. cattes et al., j. chem. phys. 144, 194704 (2016)], we study a heisenberg fluid confined to a nanoscopic slit pore with smooth walls. the pore walls can either energetically discriminate specific orientations of the molecules next to them or are indifferent to molecular orientations. unlike in paper i, we employ a version of classical density functional theory that allows us to explicitly account for the stratification of the fluid (i.e., the formatio ...201830089380
vulnerability of arctic marine mammals to vessel traffic in the increasingly ice-free northwest passage and northern sea route.the fabled northwest passage and northern sea route that were once the quests of early western explorers are now increasingly sea ice-free, with routine vessel transits expected by midcentury. the potential impacts of this novel vessel traffic on endemic arctic marine mammal (amm) species are unknown despite their critical social and ecological roles in the ecosystem and widely recognized susceptibility to ice loss. we developed a vulnerability assessment of 80 subpopulations of seven amm specie ...201829967138
foxes (vulpes vulpes) as sentinels for parasitic zoonoses, toxoplasma gondii and trichinella nativa, in the northeastern canadian arctic.outbreaks of toxoplasma gondii and trichinella spp. have been recurring for decades among inuit of nunavik, northeastern canada. contact with wildlife has been identified as a risk factor for inuit exposure to t. gondii, but reservoirs have yet to be confirmed based on direct detection of dna or organism. similarly, little is known about the occurrence of trichinella spp. in wildlife species of nunavik other than walrus (odobenus rosmarus) and bears (ursus americanus, ursus maritimus). foxes (vu ...201830370219
energetic costs of locomotion in bears: is plantigrade locomotion energetically economical?ursids are the largest mammals to retain a plantigrade posture. this primitive posture has been proposed to result in reduced locomotor speed and economy relative to digitigrade and unguligrade species, particularly at high speeds. previous energetics research on polar bears (ursus maritimus) found locomotor costs were more than double predictions for similarly sized quadrupedal mammals, which could be a result of their plantigrade posture or due to adaptations to their arctic marine existence. ...201829921569
cortical mechanisms of prioritizing selection for rejection in visual search.in visual search, the more one knows about a target, the faster one can find it. surprisingly, target identification is also faster with knowledge about distractor-features. the latter is paradoxical, as it implies that to avoid the selection of an item, the item must somehow be selected to some degree. this conundrum has been termed the "ignoring paradox", and, to date, little is known about how the brain resolves it. here, in data from four experiments using neuromagnetic brain recordings in m ...201829691330
genomic evidence of widespread admixture from polar bears into brown bears during the last ice age.recent genomic analyses have provided substantial evidence for past periods of gene flow from polar bears (ursus maritimus) into alaskan brown bears (ursus arctos), with some analyses suggesting a link between climate change and genomic introgression. however, because it has mainly been possible to sample bears from the present day, the timing, frequency, and evolutionary significance of this admixture remains unknown. here, we analyze genomic dna from three additional and geographically distinc ...201829471451
can-sine dynamics in the giant panda and three other caniformia genomes.although repeat sequences constitute about 37% of carnivore genomes, the characteristics and distribution of repeat sequences among carnivore genomes have not been fully investigated. based on the updated repbase library, we re-annotated transposable elements (tes) in four caniformia genomes (giant panda, polar bear, domestic dog, and domestic ferret) and performed a systematic, genome-wide comparison focusing on the carnivora-specific sine family, can-sines.201830455747
trichinella spiralis in a south american sea lion (otaria flavescens) from patagonia, argentina.trichinella spp. from a sylvatic cycle has been found in several animal species such as pumas (puma concolor), armadillos (chaetophractus villosus), rats (rattus norvegicus), and wild boars (sus scrofa) in argentina. moreover, trichinella infection has been detected in a wide range of marine mammals around the world, including polar bears (ursus maritimus) and walruses (odobenus rosmarus). until the present time, trichinella spp. infection has not been detected in marine mammals of south america ...201830334078
the genome of the north american brown bear or grizzly: ursus arctos ssp. horribilis.the grizzly bear (ursus arctos ssp. horribilis) represents the largest population of brown bears in north america. its genome was sequenced using a microfluidic partitioning library construction technique, and these data were supplemented with sequencing from a nanopore-based long read platform. the final assembly was 2.33 gb with a scaffold n50 of 36.7 mb, and the genome is of comparable size to that of its close relative the polar bear (2.30 gb). an analysis using 4104 highly conserved mammali ...201830513700
immune function in arctic mammals: natural killer (nk) cell-like activity in polar bear, muskox and reindeer.natural killer (nk) cells are a vital part of the rapid and non-specific immune defense against invading pathogens and tumor cells. this study evaluated nk cell-like activity by flow cytometry for the first time in three ecologically and culturally important arctic mammal species: polar bear (ursus maritimus), muskox (ovibos moschatus) and reindeer (rangifer tarandus). nk cell-like activity for all three species was most effective against the mouse lymphoma cell line yac-1, compared to the human ...201829249321
a brief review-epr dosimetry and the use of animal teeth as dosimeters.the technique of electron paramagnetic resonance dosimetry using tooth enamel was established in the late 1960s, and considerable research has been conducted to learn more about the benefits of using human teeth as dosimeters for the purpose of retrospective dose reconstruction. comparatively few studies have been done which have investigated animal teeth for the same purpose. the potential exists for utilizing animal teeth as dosimeters to reconstruct doses received by a species, as well as by ...201830260850
emission changes dwarf the influence of feeding habits on temporal trends of per- and polyfluoroalkyl substances in two arctic top predators.we monitored concentrations of per- and polyfluoroalkyl substances (pfass) in relation to climate-associated changes in feeding habits and food availability in polar bears (ursus maritimus) and arctic foxes (vulpes lagopus) (192 plasma and 113 liver samples, respectively) sampled from svalbard, norway, during 1997-2014. pfass concentrations became greater with increasing dietary trophic level, as bears and foxes consumed more marine as opposed to terrestrial food, and as the availability of sea ...201728918622
a veterinary perspective on one health in the arctic.exposure to long-range transported industrial chemicals, climate change and diseases is posing a risk to the overall health and populations of arctic wildlife. since local communities are relying on the same marine food web as marine mammals in the arctic, it requires a one health approach to understand the holistic ecosystem health including that of humans. here we collect and identify gaps in the current knowledge of health in the arctic and present the veterinary perspective of one health and ...201729246165
harvesting wildlife affected by climate change: a modelling and management approach for polar bears.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 bearursus maritimuslife 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 c ...201729081540
evolutionary history of enigmatic bears in the tibetan plateau-himalaya region and the identity of the yeti.although anecdotally associated with local bears (ursus arctos and u. thibetanus), the exact identity of 'hominid'-like creatures important to folklore and mythology in the tibetan plateau-himalaya region is still surrounded by mystery. recently, two purported yeti samples from the himalayas showed genetic affinity with an ancient polar bear, suggesting they may be from previously unrecognized, possibly hybrid, bear species, but this preliminary finding has been under question. we conducted a co ...201729187630
polar bears in the jungle: reflections on obesity and overeating. 201710614257
evolutionary adaptation and amyloid formation: does the reduced amyloidogenicity and cytotoxicity of ursine amylin contribute to the metabolic adaption of bears and polar bears?much of our knowledge of diabetes is derived from studies of rodent models. an alternative approach explores evolutionary solutions to physiological stress by studying organisms that face challenging metabolic environments. polar bears eat an enormously lipid-rich diet without deleterious metabolic consequences. in contrast, transgenic rodents expressing the human neuropancreatic polypeptide hormone amylin develop hyperglycemia and extensive pancreatic islet amyloid when fed a high fat diet. the ...201729955200
multiple-stressor effects in an apex predator: combined influence of pollutants and sea ice decline on lipid metabolism in polar bears.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 ...201729184161
environmental and behavioral changes may influence the exposure of an arctic apex predator to pathogens and contaminants.recent decline of sea ice habitat has coincided with increased use of land by polar bears (ursus maritimus) from the southern beaufort sea (sb), which may alter the risks of exposure to pathogens and contaminants. we assayed blood samples from sb polar bears to assess prior exposure to the pathogens brucella spp., toxoplasma gondii, coxiella burnetii, francisella tularensis, and neospora caninum, estimate concentrations of persistent organic pollutants (pops), and evaluate risk factors associate ...201729038498
sea-ice 'treadmill' speeds up for polar bears. 201732076341
demographic and temporal variations in immunity and condition of polar bears (ursus maritimus) from the southern beaufort sea.assessing the health and condition of animals in their natural environment can be problematic. many physiological metrics, including immunity, are highly influenced by specific context and recent events to which researchers may be unaware. thus, using a multifaceted physiological approach and a context-specific analysis encompassing multiple time scales can be highly informative. ecoimmunological tools in particular can provide important indications to the health of animals in the wild. we colle ...201729356384
morphology of the lingual papillae of the polar bear (ursus maritimus).we examined the dorsal lingual surfaces of a newborn and an old polar bears by using scanning electron microscopy. in the newborn polar bear, the filiform papilla on the lingual apex was cylindrical in shape. the connective tissue core of the filiform papillae was needle-shaped and that of the fungiform papillae was funnel-shaped. the filiform papillae on the lingual body was dome-shaped. the connective tissue core of the filiform papillae was u-shaped and that of the fungiform papillae was colu ...201729249734
a compendium and functional characterization of mammalian genes involved in adaptation to arctic or antarctic environments.many mammals are well adapted to surviving in extremely cold environments. these species have likely accumulated genetic changes that help them efficiently cope with low temperatures. it is not known whether the same genes related to cold adaptation in one species would be under selection in another species. the aims of this study therefore were: to create a compendium of mammalian genes related to adaptations to a low temperature environment; to identify genes related to cold tolerance that hav ...201729297313
ad-libs: inferring ancestry across hybrid genomes using low-coverage sequence data.inferring the ancestry of each region of admixed individuals' genomes is useful in studies ranging from disease gene mapping to speciation genetics. current methods require high-coverage genotype data and phased reference panels, and are therefore inappropriate for many data sets. we present a software application, ad-libs, that uses a hidden markov model to infer ancestry across hybrid genomes without requiring variant calling or phasing. this approach is useful for non-model organisms and in c ...201728376731
responses of urban crows to con- and hetero-specific alarm calls in predator and non-predator zoo enclosures.urban animals and birds in particular are able to cope with diverse novel threats in a city environment such as avoiding novel, unfamiliar predators. predator avoidance often includes alarm signals that can be used also by hetero-specifics, which is mainly the case in mixed-species flocks. it can also occur when species do not form flocks but co-occur together. in this study we tested whether urban crows use alarm calls of conspecifics and hetero-specifics (jackdaws, corvus monedula) differently ...201727796660
analysis of zp1 gene reveals differences in zona pellucida composition in carnivores.the zona pellucida (zp) is an extracellular envelope that surrounds mammalian oocytes. this coat participates in the interaction between gametes, induction of the acrosome reaction, block of polyspermy and protection of the oviductal embryo. previous studies suggested that carnivore zp was formed by three glycoproteins (zp2, zp3 and zp4), with zp1 being a pseudogene. however, a recent study in the cat found that all four proteins were expressed. in the present study, in silico and molecular anal ...201728679462
endosulfan, short-chain chlorinated paraffins (sccps) and octachlorostyrene in wildlife from greenland: levels, trends and methodological challenges.besides globally banned "legacy" persistent organic pollutants, other compounds might be present in arctic wildlife, for which regulation was introduced recently (the insecticide endosulfan), is considered (short-chain chlorinated paraffins, sccps) or does not exist (octachlorostyrene, ocs, a byproduct of manufacturing and combustion processes involving chlorine). the purpose of this study was to analyze the time trend of endosulfan (1986-2012) in ringed seals and to address the levels of sccps ...201728667423
habitat degradation affects the summer activity of polar bears.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 ...201728247129
increasing nest predation will be insufficient to maintain polar bear body condition in the face of sea ice loss.climate change can influence interspecific interactions by differentially affecting species-specific phenology. in seasonal ice environments, there is evidence that polar bear predation of arctic bird eggs is increasing because of earlier sea ice breakup, which forces polar bears into nearshore terrestrial environments where arctic birds are nesting. because polar bears can consume a large number of nests before becoming satiated, and because they can swim between island colonies, they could hav ...201727614094
a rapid analytical method to quantify complex organohalogen contaminant mixtures in large samples of high lipid mammalian tissues.in vitro investigations of the health impact of individual chemical compounds have traditionally been used in risk assessments. however, humans and wildlife are exposed to a plethora of potentially harmful chemicals, including organohalogen contaminants (ohcs). an alternative exposure approach to individual or simple mixtures of synthetic ohcs is to isolate the complex mixture present in free-ranging wildlife, often non-destructively sampled from lipid rich adipose. high concentration stock volu ...201728273531
effects of polar bear and killer whale derived contaminant cocktails on marine mammal immunity.most controlled toxicity studies use single chemical exposures that do not represent the real world situation of complex mixtures of known and unknown natural and anthropogenic substances. in the present study, complex contaminant cocktails derived from the blubber of polar bears (pb; ursus maritimus) and killer whales (kw; orcinus orca) were used for in vitro concentration-response experiments with pb, cetacean and seal spp. immune cells to evaluate the effect of realistic contaminant mixtures ...201728876915
an arctic predator-prey system in flux: climate change impacts on coastal space use by polar bears and ringed seals.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 occur ...201728415134
risk of pop mixtures on the arctic food chain.the exposure of the arctic ecosystem to persistent organic pollutants (pops) was assessed through a review of literature data. concentrations of 19 chemicals or congeneric groups were estimated for the highest levels of the arctic food chain (arctic cod, ringed seals, and polar bears). the ecotoxicological risk for seals, bears, and bear cubs was estimated by applying the concentration addition (ca) concept. the risk of pop mixtures was very low in seals. by contrast, the risk was 2 orders of ma ...201728054401
isotopic incorporation and the effects of fasting and dietary lipid content on isotopic discrimination in large carnivorous mammals.there has been considerable emphasis on understanding isotopic discrimination for diet estimation in omnivores. however, discrimination may differ for carnivores, particularly species that consume lipid-rich diets. here, we examined the potential implications of several factors when using stable isotopes to estimate the diets of bears, which can consume lipid-rich diets and, alternatively, fast for weeks to months. we conducted feeding trials with captive brown bears (ursus arctos) and polar bea ...201727153128
demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability.to assess whether demographic declines of arctic species at the southern limit of their range will be gradual or punctuated, we compared large-scale environmental patterns including sea ice dynamics to ringed seal (pusa hispida) reproduction, body condition, recruitment, and stress in hudson bay from 2003 to 2013. aerial surveys suggested a gradual decline in seal density from 1995 to 2013, with the lowest density occurring in 2013. body condition decreased and stress (cortisol) increased over t ...201728168119
comparison of methanol and isopropanol as wash solvents for determination of hair cortisol concentration in grizzly bears and polar bears.methodological differences among laboratories are recognized as significant sources of variation in quantification of hair cortisol concentration (hcc). an important step in processing hair, particularly when collected from wildlife, is the choice of solvent used to remove or "wash" external hair shaft cortisol prior to quantification of hcc. the present study systematically compared methanol and isopropanol as wash solvents for their efficiency at removing external cortisol without extracting i ...201728203534
postlaparoscopic reduction of pain by combining intraperitoneal normal saline and the pulmonary recruitment maneuver (polar bear trial). rct to estimate reduction in pain after laparoscopic surgery when using a combination therapy of intraperitoneal normal saline and the pulmonary recruitment maneuver.shoulder pain and pain in the upper abdomen are common complaints after laparoscopy, sometimes surpassing the pain at incision sites. the incidence of shoulder pain ranges from 35 to 80%. post-laparoscopic pain is caused by retention of carbon dioxide in the abdomen, which irritates the phrenic nerve and diaphragm, causing referred pain in the shoulder and in the upper abdomen. a promising strategy to reduce this post-laparoscopic pain is the pulmonary recruitment maneuver, which indirectly incr ...201728610572
diet and metabolic state are the main factors determining concentrations of perfluoroalkyl substances in female polar bears from svalbard.perfluoroalkyl substances (pfass) have been detected in organisms worldwide, including polar regions. the polar bear (ursus maritimus), the top predator of arctic marine ecosystems, accumulates high concentrations of pfass, which may be harmful to their health. the aim of this study was to investigate which factors (habitat quality, season, year, diet, metabolic state [i.e. feeding/fasting], breeding status and age) predict pfas concentrations in female polar bears captured on svalbard (norway). ...201728587979
trichinella and polar bears: a limited risk for humans.in this review, we identified 63 cases reported since world war ii of human trichinellosis linked to the consumption of parasitized polar bear (ursus maritimus) meat. this low number contrasts to the numerous cases of human trichinellosis related to consumption of the meat of black (u. americanus) or brown bears (u. arctos). the prevalence of trichinella infection is high in bears, but larval muscular burden is usually lower in polar bears compared to other bear species. polar bears, therefore, ...201728372597
depressive symptomatology and priming effects among younger and older adults.background/study context: this study examined the potential impact of self-reported depressive symptoms on the age-related capacity for inhibition and suppression, utilizing a negative priming paradigm.201728067611
increased arctic sea ice drift alters adult female polar bear movements and energetics.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 s ...201728586523
variables affecting the manifestation of and intensity of pacing behavior: a preliminary case study in zoo-housed polar bears.high-speed video analysis was used to quantify two aspects of gait in 10 zoo-housed polar bears. these two variables were then examined as to how they differed in the conditions of pacing versus locomoting for each bear. percent difference calculations measured the difference between pacing and locomoting data for each bear. we inferred that the higher the percent difference between pacing and locomoting in a given subject, the more intense the pacing may be. the percent difference values were a ...201728901667
simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data.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, ...201728861216
polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer.when reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions during hibernation. polar bears may be food deprived and relatively inactive during winter (when pregnant females hibernate and hunting success declines for other demographic groups) as well as summer (when sea ice retreats from key foraging habitats). we investigated muscle a ...201728835844
urinary profiles of progestin and androgen metabolites in female polar bears during parturient and non-parturient cycles.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 s ...201728458884
relationships between pops, biometrics and circulating steroids in male polar bears (ursus maritimus) from svalbard.the aim of this study was to determine the effects of persistent organic pollutants (pops) and biometric variables on circulating levels of steroid hormones (androgens, estrogens and progestagens) in male polar bears (ursus maritimus) from svalbard, norway (n = 23). levels of pregnenolone (pre), progesterone (pro), androstenedione (an), dehydroepiandrosterone (dhea), testosterone (ts), dihydrotestosterone (dht), estrone (e1), 17α-estradiol (αe2) and 17β-estradiol (βe2) were quantified in polar b ...201728710978
analysis and characterization of polychlorinated hydroxybornanes as metabolites of toxaphene using a polar bear model.abiotic and biotic transformation of toxaphene (camphechlor) results in the selective enrichment of recalcitrant congeners while other, less persistent compounds of technical toxaphene (ctts) are degraded. until now, there has been little knowledge on oxidation transformation of toxaphene. for instance, the existence of hydroxylated ctts (oh-ctts) in authentic environmental and food samples has not been proven. for this reason, we synthesized a mixture consisting of tetra- to heptachlorinated oh ...201728686017
movement of a female polar bear (ursus maritimus) in the kara sea during the summer sea-ice break-up.the polar bear movement trajectory in relation to onset date of the sea-ice break-up was studied in the coastal zone of the taimyr peninsula, eastern part of the kara sea, using as an example a female polar bear tagged by a radio collar with an argos satellite transmitter. analysis of the long-term pattern of ice melting and tracking, by means of satellite telemetry, of the female polar bear who followed the ice-edge outgoing in the north-eastern direction (in summer 2012) suggests that directio ...201728429262
corrigendum to "sea ice-associated decline in body condition leads to increased concentrations of lipophilic pollutants in polar bears (ursus maritimus) from svalbard, norway" [sci. total environ. 576 (2017) 409-419]. 201728411564
windscapes and olfactory foraging in a large carnivore.the theoretical optimal olfactory search strategy is to move cross-wind. empirical evidence supporting wind-associated directionality among carnivores, however, is sparse. we examined satellite-linked telemetry movement data of adult female polar bears (ursus maritimus) from hudson bay, canada, in relation to modelled winds, in an effort to understand olfactory search for prey. in our results, the predicted cross-wind movement occurred most frequently at night during winter, the time when most h ...201728402340
predator-prey-subsidy population dynamics on stepping-stone domains.predator-prey-subsidy dynamics on stepping-stone domains are examined using a variety of network configurations. our problem is motivated by the interactions between arctic foxes (predator) and lemmings (prey) in the presence of seal carrion (subsidy) provided by polar bears. we use the n-patch model, which considers space explicitly as a "stepping stone" system. we consider the role that the carrying capacity, predator migration rate, input subsidy rate, predator mortality rate, and proportion ...201728322876
combined thin layer chromatography and gas chromatography with mass spectrometric analysis of lipid classes and fatty acids in malnourished polar bears (ursus maritimus) which swam to iceland.between 2008 and 2011, four polar bears (ursus maritimus) from the greenland population swam and/or drifted on ice to iceland where they arrived in very poor body condition. body fat resources in these animals were only between 0% and 10% of the body weight (usually 25%). here we studied the lipid composition in different tissues (adipose tissue if available, liver, kidney and muscle). lipid classes were determined by thin layer chromatography (tlc) and on-column gas chromatography with mass spe ...201728183043
legacy and new halogenated persistent organic pollutants in polar bears from a contamination hotspot in the arctic, hudson bay canada.a large and complex suite of 295 legacy and new halogenated persistent organic pollutants (pops) were investigated in fat or liver tissue samples of polar bears collected in 2013-2014 from southern (shb) and western (whb) subpopulations of the canadian arctic contaminants hotspot of hudson bay. a total of 210 pops were detected and/or quantifiable with some frequency in all fat or liver samples. pop profile and concentration differences were investigated both within (e.g. age and sex) and betwee ...201728803190
comparative genomics analyses of alpha-keratins reveal insights into evolutionary adaptation of marine mammals.diversity of hair in marine mammals was suggested as an evolutionary innovation to adapt aquatic environment, yet its genetic basis remained poorly explored. we scanned α-keratin genes, one major structural components of hair, in 16 genomes of mammalian species, including seven cetaceans, two pinnipeds, polar bear, manatee and five terrestrial species.201728785294
mass loss rates of fasting polar bears.polar bears (ursus maritimus) have adapted to an annual cyclic regime of feeding and fasting, which is extreme in seasonal sea ice regions of the arctic. as a consequence of climate change, sea ice breakup has become earlier and the duration of the open-water period through which polar bears must rely on fat reserves has increased. to date, there is limited empirical data with which to evaluate the potential energetic capacity of polar bears to withstand longer fasts. we measured the incoming an ...201727617359
dental and temporomandibular joint pathology of the polar bear (ursus maritimus).museum specimens (maxillae and/or mandibles) from 317 polar bears (ursus maritimus) were examined macroscopically according to predefined criteria and 249 specimens were included in this study. the specimens were acquired between 1906 and 2011. there were 126 specimens (50.6%) from male animals, 93 (37.3%) from female animals and 30 (12.1%) from animals of unknown sex. the ages of the animals ranged from neonate to adult, with 125 adults (50.2%) and 124 young adults (49.8%) included and neonates ...201727481648
lumbar laminectomy in a captive, adult polar bear (ursus maritimus).animals held in captivity tend to live longer than do their wild counterparts, and as such, are prone to developing age-related degenerative injuries. here, we present a case of an adult female polar bear with symptomatic lumbar stenosis. there is a paucity of literature on large mammalian spine surgery, and anatomical differences between humans and other vertebrates must be taken into consideration.201728680731
potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (ursus maritimus) from the barents sea.as apex predators, polar bears (ursus maritimus) are among the most heavily polluted organisms in the arctic. in addition to this anthropogenic stressor, climate warming has been shown to negatively affect their body condition, reproductive output and survival. among potential underlying physiological mechanisms, thyroid hormones (ths), which control thermoregulation, metabolism and reproduction, can be affected by a variety of both natural and anthropogenic factors. while ths have been extensiv ...201728614731
ecological change drives a decline in mercury concentrations in southern beaufort sea polar bears.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 sampl ...201728612610
sea ice-associated decline in body condition leads to increased concentrations of lipophilic pollutants in polar bears (ursus maritimus) from svalbard, norway.global climate changes are magnified in the arctic and are having an especially dramatic effect on the spatial and temporal distribution and the thickness traits of sea ice. decline of arctic sea ice may lead to qualitative and/or quantitative changes in diet and reduced body condition (i.e. adipose tissue stores) of ice-associated apex predators such as polar bears (ursus maritimus). this may further affect their tissue concentrations of lipophilic pollutants. we determined how variations in ad ...201727794227
conceptual and linguistic representations of kinds and classes.we investigate the hypothesis that our conceptual systems provide two formally distinct ways of representing categories by investigating the manner in which lexical nominals (e.g., tree, picnic table) and phrasal nominals (e.g., black bird, birds that like rice) are interpreted. four experiments found that lexical nominals may be mapped onto kind representations, whereas phrasal nominals map onto class representations but not kind representations. experiment 1 found that phrasal nominals, unlike ...201722671567
[the possibility of using high resolution satellite images for detection of marine mammals].the possibility of using modern systems of remote sensing in the optical range from high spatial resolution satellites for detection of marine mammals and traces of their activity is investigated. an image obtained by the geoeye satellite within the feac project was used for the analysis. the image covers herald island and adjacent waters, which are a part of the wrangel island reserve, during the seasonal thaw (june 2009). it is shown that marine mammals (polar bears, walruses, and whales) can ...201623789427
per- and polyfluoroalkyl substances (pfass) - new endocrine disruptors in polar bears (ursus maritimus)?per- and polyfluoroalkyl substances (pfass) are emerging in the arctic and accumulate in brain tissues of east greenland (eg) polar bears. in vitro studies have shown that pfass might possess endocrine disrupting abilities and therefore the present study was conducted to investigate potential pfas induced alterations in brain steroid concentrations. the concentrations of eleven steroid hormones were determined in eight brain regions from ten eg polar bears. pregnenolone (pre), the dominant proge ...201627692342
demographic and traditional knowledge perspectives on the current status of canadian polar bear subpopulations.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 ...201627069588
involuntary symbol manipulation (pig latin) from external control: implications for thought suppression.in ironic processing, one is more likely to think about something (e.g., white bears) when instructed to not think about that thing. entry into consciousness of such content may be automatic, reflecting the 'encapsulated' nature of the generation of conscious contents. based on this research, the reflexive imagery task (rit) reveals that, following the activation of action sets, conscious contents can arise involuntarily and systematically in response to external stimuli. in the most basic versi ...201627043254
costs of locomotion in polar bears: when do the costs outweigh the benefits of chasing down terrestrial prey?trade-offs between locomotory costs and foraging gains are key elements in determining constraints on predator-prey interactions. one intriguing example involves polar bears pursuing snow geese on land. as climate change forces polar bears to spend more time ashore, they may need to expend more energy to obtain land-based food. given that polar bears are inefficient at terrestrial locomotion, any extra energy expended to pursue prey could negatively impact survival. however, polar bears have bee ...201627757238
taming the white bear: initial costs and eventual benefits of distractor inhibition.previous research indicates that prior information about a target feature, such as its color, can speed search. can search also be speeded by knowing what a target willnotlook like? in the two experiments reported here, participants searched for target letters. prior to viewing search displays, participants were prompted either with the color in which one or more nontarget letters would appear (ignore trials) or with no information about the search display (neutral trials). critically, when part ...201626893292
distinct mechanisms for distractor suppression and target facilitation.it is well established that preparatory attention improves processing of task-relevant stimuli. although it is often more important to ignore task-irrelevant stimuli, comparatively little is known about preparatory attentional mechanisms for inhibiting expected distractions. here, we establish that distractor inhibition is not under the same top-down control as target facilitation. using a variant of the posner paradigm, participants were cued to either the location of a target stimulus, the loc ...201626865606
evaluation of hepatic biotransformation of polybrominated diphenyl ethers in the polar bear (ursus maritimus).polar bears are at the top of the arctic marine food chain and are subject to exposure and bioaccumulation of environmental chemicals of concern such as polybrominated diphenyl ethers (pbdes), which were widely used as flame retardants. the aim of the present study was to evaluate the in vitro oxidative metabolism of 2,2',4,4'-tetrabrominated diphenyl ether (bde-47) and 2,2',4,4',5-pentabrominated diphenyl ether (bde-99) by polar bear liver microsomes. the identification and quantification of th ...201626745384
immunotoxic effects of environmental pollutants in marine mammals.due to their marine ecology and life-history, marine mammals accumulate some of the highest levels of environmental contaminants of all wildlife. given the increasing prevalence and severity of diseases in marine wildlife, it is imperative to understand how pollutants affect the immune system and consequently disease susceptibility. advancements and adaptations of analytical techniques have facilitated marine mammal immunotoxicology research. field studies, captive-feeding experiments and in vit ...201626590481
conservation status of polar bears (ursus maritimus) in relation to projected sea-ice declines.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 approach ...201627928000
allee effect in polar bears: a potential consequence of polychlorinated biphenyl contamination.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 link ...201627903868
hair mercury concentrations in western hudson bay polar bear family groups.methylmercury is one of the more toxic forms of mercury (hg), the biomagnification of which is prevalent in the arctic where apex predators such as polar bears (ursus maritimus) can carry high loads. the maternal transfer of contaminants to offspring is a concern, as offspring may be particularly sensitive to the effects of environmental pollutants during early development. however, few studies of polar bears report on hg in dependent young. we examined hair total hg (thg) concentrations in 24 p ...201627095340
geographical area and life history traits influence diet in an arctic marine predator.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 ...201627196700
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