1
|
Jongsomjit D, Lescroël A, Schmidt AE, Lisovski S, Ainley DG, Hines E, Elrod M, Dugger KM, Ballard G. Going with the floe: Sea-ice movement affects distance and destination during Adélie penguin winter movements. Ecology 2024; 105:e4196. [PMID: 37885122 DOI: 10.1002/ecy.4196] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 08/22/2023] [Accepted: 09/19/2023] [Indexed: 10/28/2023]
Abstract
Seasonal migration, driven by shifts in annual climate cycles and resources, is a key part of the life history and ecology of species across taxonomic groups. By influencing the amount of energy needed to move, external forces such as wind and ocean currents are often key drivers of migratory pathways exposing individuals to varying resources, environmental conditions, and competition pressures impacting individual fitness and population dynamics. Although wildlife movements in connection with wind and ocean currents are relatively well understood, movements within sea-ice fields have been much less studied, despite sea ice being an integral part of polar ecology. Adélie penguins (Pygoscelis adeliae) in the southern Ross Sea, Antarctica, currently exist at the southernmost edge of their range and undergo the longest (~12,000 km) winter migration known for the species. Within and north of the Ross Sea, the Ross Gyre drives ocean circulation and the large-scale movement of sea ice. We used remotely sensed sea-ice movement data together with geolocation-based penguin movement data to test the hypothesis that penguins use gyre-driven sea-ice movement to aid their migration. We found that penguins traveled greater distances when their movement vectors were aligned with those of sea ice (i.e., ice support) and the amount of ice support received depended on which route a penguin took. We also found that birds that took an eastern route traveled significantly further north in two of the 3 years we examined, coinciding with higher velocities of sea ice in those years. We compare our findings to patterns observed in migrating species that utilize air or water currents for their travel and with other studies showing the importance of ocean/sea-ice circulation patterns to wildlife movement and life history patterns within the Ross Sea. Changes in sea ice may have consequences not only for energy expenditure but, by altering migration and movement pathways, to the ecological interactions that exist in this region.
Collapse
Affiliation(s)
- Dennis Jongsomjit
- Point Blue Conservation Science, Petaluma, California, USA
- Department of Geography and Environment, San Francisco State University, San Francisco, California, USA
| | | | | | - Simeon Lisovski
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany
| | | | - Ellen Hines
- Department of Geography and Environment, San Francisco State University, San Francisco, California, USA
- Estuary & Ocean Science Center, San Francisco State University, Tiburon, California, USA
| | - Megan Elrod
- Point Blue Conservation Science, Petaluma, California, USA
| | - Katie M Dugger
- US Geological Survey, Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Grant Ballard
- Point Blue Conservation Science, Petaluma, California, USA
| |
Collapse
|
2
|
Rode KD, Taras BD, Stricker CA, Atwood TC, Boucher NP, Durner GM, Derocher AE, Richardson ES, Cherry SG, Quakenbush L, Horstmann L, Bromaghin JF. Diet energy density estimated from isotopes in predator hair associated with survival, habitat, and population dynamics. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2023; 33:e2751. [PMID: 36151883 DOI: 10.1002/eap.2751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 07/29/2022] [Accepted: 08/30/2022] [Indexed: 06/16/2023]
Abstract
Sea ice loss is fundamentally altering the Arctic marine environment. Yet there is a paucity of data on the adaptability of food webs to ecosystem change, including predator-prey interactions. Polar bears (Ursus maritimus) are an important subsistence resource for Indigenous people and an apex predator that relies entirely on the under-ice food web to meet its energy needs. In this study, we assessed whether polar bears maintained dietary energy density by prey switching in response to spatiotemporal variation in prey availability. We compared the macronutrient composition of diets inferred from stable carbon and nitrogen isotopes in polar bear guard hair (primarily representing summer/fall diet) during periods when bears had low and high survival (2004-2016), between bears that summered on land versus pack ice, and between bears occupying different regions of the Alaskan and Canadian Beaufort Sea. Polar bears consumed diets with lower energy density during periods of low survival, suggesting that concurrent increased dietary proportions of beluga whales (Delphinapterus leucas) did not offset reduced proportions of ringed seals (Pusa hispida). Diets with the lowest energy density and proportions from ringed seal blubber were consumed by bears in the western Beaufort Sea (Alaska) during a period when polar bear abundance declined. Intake required to meet energy requirements of an average free-ranging adult female polar bear was 2.1 kg/day on diets consumed during years with high survival but rose to 3.0 kg/day when survival was low. Although bears that summered onshore in the Alaskan Beaufort Sea had higher-fat diets than bears that summered on the pack ice, access to the remains of subsistence-harvested bowhead whales (Balaena mysticetus) contributed little to improving diet energy density. Because most bears in this region remain with the sea ice year round, prey switching and consumption of whale carcasses onshore appear insufficient to augment diets when availability of their primary prey, ringed seals, is reduced. Our results show that a strong predator-prey relationship between polar bears and ringed seals continues in the Beaufort Sea. The method of estimating dietary blubber using predator hair, demonstrated here, provides a new metric to monitor predator-prey relationships that affect individual health and population demographics.
Collapse
Affiliation(s)
- Karyn D Rode
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Brian D Taras
- Alaska Department of Fish and Game, Fairbanks, Alaska, USA
| | - Craig A Stricker
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA
| | - Todd C Atwood
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | - Nicole P Boucher
- University of Alberta, Edmonton, Alberta, Canada
- School of Environmental Studies, University of Victoria, Victoria, British Columbia, Canada
| | - George M Durner
- U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA
| | | | - Evan S Richardson
- Environment and Climate Change Canada, Science and Technology Branch, Winnipeg, Manitoba, Canada
| | - Seth G Cherry
- University of Alberta, Edmonton, Alberta, Canada
- Parks Canada, East Kootenay, British Columbia, Canada
| | | | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | | |
Collapse
|
3
|
Togunov RR, Derocher AE, Lunn NJ, Auger-Méthé M. Drivers of polar bear behavior and the possible effects of prey availability on foraging strategy. MOVEMENT ECOLOGY 2022; 10:50. [PMID: 36384775 PMCID: PMC9670556 DOI: 10.1186/s40462-022-00351-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/09/2022] [Indexed: 06/05/2023]
Abstract
BACKGROUND Change in behavior is one of the earliest responses to variation in habitat suitability. It is therefore important to understand the conditions that promote different behaviors, particularly in areas undergoing environmental change. Animal movement is tightly linked to behavior and remote tracking can be used to study ethology when direct observation is not possible. METHODS We used movement data from 14 polar bears (Ursus maritimus) in Hudson Bay, Canada, during the foraging season (January-June), when bears inhabit the sea ice. We developed an error-tolerant method to correct for sea ice drift in tracking data. Next, we used hidden Markov models with movement and orientation relative to wind to study three behaviors (stationary, area-restricted search, and olfactory search) and examine effects of 11 covariates on behavior. RESULTS Polar bears spent approximately 47% of their time in the stationary drift state, 29% in olfactory search, and 24% in area-restricted search. High energy behaviors occurred later in the day (around 20:00) compared to other populations. Second, olfactory search increased as the season progressed, which may reflect a shift in foraging strategy from still-hunting to active search linked to a shift in seal availability (i.e., increase in haul-outs from winter to the spring pupping and molting seasons). Last, we found spatial patterns of distribution linked to season, ice concentration, and bear age that may be tied to habitat quality and competitive exclusion. CONCLUSIONS Our observations were generally consistent with predictions of the marginal value theorem, and differences between our findings and other populations could be explained by regional or temporal variation in resource availability. Our novel movement analyses and finding can help identify periods, regions, and conditions of critical habitat.
Collapse
Affiliation(s)
- Ron R. Togunov
- Institute for the Oceans and Fisheries, The University of British Columbia, V6T 1Z4 Vancouver, Canada
- Department of Zoology, The University of British Columbia, Vancouver, V6T 1Z4 Canada
| | - Andrew E. Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, T6G 2E9 Canada
| | - Nicholas J. Lunn
- Wildlife Research Division, Science and Technology Branch, Environment and Climate Change Canada, Edmonton, T6G 2E9 Canada
| | - Marie Auger-Méthé
- Institute for the Oceans and Fisheries, The University of British Columbia, V6T 1Z4 Vancouver, Canada
- Department of Statistics, The University of British Columbia, Vancouver, V6T 1Z4 Canada
| |
Collapse
|
4
|
Patil VP, Durner GM, Douglas DC, Atwood TC. Modeling the spatial and temporal dynamics of land‐based polar bear denning in Alaska. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Vijay P. Patil
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage AK 99508 USA
| | - George M. Durner
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage AK 99508 USA
| | - David C. Douglas
- Alaska Science Center U.S. Geological Survey 250 Egan Drive Juneau AK 99801 USA
| | - Todd C. Atwood
- Alaska Science Center U.S. Geological Survey 4210 University Drive Anchorage AK 99508 USA
| |
Collapse
|
5
|
Griffen BD, Whiteman JP, Pullan S. Significance of autumn and winter food consumption for reproduction by Southern Beaufort Sea polar bears, Ursus maritimus. Polar Biol 2022. [DOI: 10.1007/s00300-022-03066-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
AbstractPolar bears (Ursus maritimus) in the southern Beaufort Sea experience long annual periods when preferred seal prey are scarce or are unavailable. Consumption of bowhead whale (Balaena mysticetus) carcasses from native Alaskan subsistence hunting is increasingly common for onshore polar bears, yet the energetic consequences of this consumption remain unclear. We use data on bears captured repeatedly over periods that encompassed autumn and winter, combined with calculations, to show that adult female bears likely consume an average of at least 4 seal equivalents during both autumn and winter periods and that considerable variation in energy intake exists across individual bears. We further show that subsistence-caught whale carcasses provide an upper threshold of > 4000 seal equivalents, which could potentially meet mean consumption needs of ~ 80% of the southern Beaufort Sea bear subpopulation during autumn and winter periods. Finally, we modify an existing model to show that observed mass changes over autumn and winter could substantially alter spring foraging habitat choice by females with cubs and the chance that a female with reduced energy reserves would abort a pregnancy or abandon cubs in favor of increasing her own survival; these behaviors could potentially influence population vital rates. Our study highlights the importance of mass dynamics over the autumn and winter months, points to the need for additional data on foraging and energetics over this period, and indicates that the recent declines in polar bear body condition in some subpopulations could have complex effects on reproduction.
Collapse
|
6
|
Klappstein NJ, Potts JR, Michelot T, Börger L, Pilfold NW, Lewis MA, Derocher AE. Energy‐based step selection analysis: modelling the energetic drivers of animal movement and habitat use. J Anim Ecol 2022; 91:946-957. [DOI: 10.1111/1365-2656.13687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 02/17/2022] [Indexed: 11/30/2022]
Affiliation(s)
| | - Jonathan R. Potts
- School of Mathematics and Statistics University of Sheffield, Hicks Building, Hounsfield Road Sheffield UK
| | - Théo Michelot
- Centre for Research into Ecological and Environmental Modelling University of St Andrews St Andrews UK
| | - Luca Börger
- Department of Biosciences Swansea University Swansea UK
- Centre for Biomathematics, College of Science Swansea University Swansea UK
| | - Nicholas W. Pilfold
- Conservation Science and Wildlife Health, San Diego Zoo Wildlife Alliance San Diego USA
| | - Mark A. Lewis
- Department of Biological Sciences University of Alberta Edmonton Canada
- Department of Mathematical and Statistical Sciences University of Alberta Edmonton Canada
| | | |
Collapse
|
7
|
Atwood TC, Rode KD, Douglas DC, Simac K, Pagano AM, Bromaghin JF. Long-term variation in polar bear body condition and maternal investment relative to a changing environment. Glob Ecol Conserv 2021. [DOI: 10.1016/j.gecco.2021.e01925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
8
|
Pagano AM, Durner GM, Atwood TC, Douglas DC. Effects of sea ice decline and summer land use on polar bear home range size in the Beaufort Sea. Ecosphere 2021. [DOI: 10.1002/ecs2.3768] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Anthony M. Pagano
- U.S. Geological Survey Alaska Science Center Anchorage Alaska 99508 USA
| | - George M. Durner
- U.S. Geological Survey Alaska Science Center Anchorage Alaska 99508 USA
| | - Todd C. Atwood
- U.S. Geological Survey Alaska Science Center Anchorage Alaska 99508 USA
| | - David C. Douglas
- U.S. Geological Survey Alaska Science Center Juneau Alaska 99801 USA
| |
Collapse
|
9
|
Bromaghin JF, Douglas DC, Durner GM, Simac KS, Atwood TC. Survival and abundance of polar bears in Alaska's Beaufort Sea, 2001-2016. Ecol Evol 2021; 11:14250-14267. [PMID: 34707852 PMCID: PMC8525099 DOI: 10.1002/ece3.8139] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/02/2021] [Accepted: 09/06/2021] [Indexed: 12/20/2022] Open
Abstract
The Arctic Ocean is undergoing rapid transformation toward a seasonally ice-free ecosystem. As ice-adapted apex predators, polar bears (Ursus maritimus) are challenged to cope with ongoing habitat degradation and changes in their prey base driven by food-web response to climate warming. Knowledge of polar bear response to environmental change is necessary to understand ecosystem dynamics and inform conservation decisions. In the southern Beaufort Sea (SBS) of Alaska and western Canada, sea ice extent has declined since satellite observations began in 1979 and available evidence suggests that the carrying capacity of the SBS for polar bears has trended lower for nearly two decades. In this study, we investigated the population dynamics of polar bears in Alaska's SBS from 2001 to 2016 using a multistate Cormack-Jolly-Seber mark-recapture model. States were defined as geographic regions, and we used location data from mark-recapture observations and satellite-telemetered bears to model transitions between states and thereby explain heterogeneity in recapture probabilities. Our results corroborate prior findings that the SBS subpopulation experienced low survival from 2003 to 2006. Survival improved modestly from 2006 to 2008 and afterward rebounded to comparatively high levels for the remainder of the study, except in 2012. Abundance moved in concert with survival throughout the study period, declining substantially from 2003 and 2006 and afterward fluctuating with lower variation around an average of 565 bears (95% Bayesian credible interval [340, 920]) through 2015. Even though abundance was comparatively stable and without sustained trend from 2006 to 2015, polar bears in the Alaska SBS were less abundant over that period than at any time since passage of the U.S. Marine Mammal Protection Act. The potential for recovery is likely limited by the degree of habitat degradation the subpopulation has experienced, and future reductions in carrying capacity are expected given current projections for continued climate warming.
Collapse
Affiliation(s)
| | | | | | | | - Todd C. Atwood
- U.S. Geological SurveyAlaska Science CenterAnchorageAKUSA
| |
Collapse
|
10
|
Galicia MP, Thiemann GW, Dyck MG, Ferguson SH. Are tissue samples obtained via remote biopsy useful for fatty acid-based diet analyses in a free-ranging carnivore? J Mammal 2021. [DOI: 10.1093/jmammal/gyab041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Fundamental knowledge on free-ranging animals has been obtained through capture-based studies; however, these may be logistically intensive, financially expensive, and potentially inconsistent with local cultural values. Genetic mark–recapture using remote tissue sampling has emerged as a less invasive alternative to capture-based population surveys but provides fewer opportunities to collect samples and measurements for broader ecological studies. We compared lipid content, fatty acid (FA) composition, and diet estimates from adipose tissue of polar bears (Ursus maritimus) obtained from two collection methods: remote biopsies (n = 138) sampled from helicopters and hunter-collected tissue (n = 499) from bears harvested in Davis Strait and Gulf of Boothia, Nunavut, 2010 – 2018. Lipid content of adipose tissue was lower in remote biopsies than harvest samples likely because remote biopsies removed only the outermost layer of subcutaneous tissue, rather than the more metabolically dynamic innermost tissue obtained from harvest samples. In contrast, FA composition was similar between the two collection methods with relatively small proportional differences in individual FAs. For diet estimates in Davis Strait, collection method was not a predictor of prey contribution to diet. In Gulf of Boothia, collection method was a predictor for some prey types, but the differences were relatively minor; the rank order of prey types was similar (e.g., ringed seal; Pusa hispida was consistently the primary prey in diets) and prey proportions differed by < 6% between the collection methods. Results from both methods showed that diets varied by geographic area, season, year, age class, and sex. Our study demonstrates that adipose tissue from remote biopsy provides reliable estimates of polar bear diet based on FA analysis and can be used to monitor underlying ecological changes in Arctic marine food webs.
Collapse
Affiliation(s)
| | - Gregory W Thiemann
- Faculty of Environmental and Urban Change, York University, Toronto, Ontario, Canada
| | - Markus G Dyck
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, Nunavut, Canada
| | - Steven H Ferguson
- Fisheries and Oceans Canada, Central and Arctic Region, Winnipeg, Manitoba, Canada
| |
Collapse
|
11
|
Pagano AM, Williams TM. Physiological consequences of Arctic sea ice loss on large marine carnivores: unique responses by polar bears and narwhals. J Exp Biol 2021; 224:224/Suppl_1/jeb228049. [PMID: 33627459 DOI: 10.1242/jeb.228049] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Rapid environmental changes in the Arctic are threatening the survival of marine species that rely on the predictable presence of the sea ice. Two Arctic marine mammal specialists, the polar bear (Ursus maritimus) and narwhal (Monodon monoceros), appear especially vulnerable to the speed and capriciousness of sea ice deterioration as a consequence of their unique hunting behaviors and diet, as well as their physiological adaptations for slow-aerobic exercise. These intrinsic characteristics limit the ability of these species to respond to extrinsic threats associated with environmental change and increased industrial activity in a warming Arctic. In assessing how sea ice loss may differentially affect polar bears that hunt on the ice surface and narwhals that hunt at extreme depths below, we found that major ice loss translated into elevated locomotor costs that range from 3- to 4-fold greater than expected for both species. For polar bears this instigates an energy imbalance from the combined effects of reduced caloric intake and increased energy expenditure. For narwhals, high locomotor costs during diving increase the risk of ice entrapment due to the unreliability of breathing holes. These species-specific physiological constraints and extreme reliance on the polar sea ice conspire to make these two marine mammal specialists sentinels of climate change within the Arctic marine ecosystem that may foreshadow rapid changes to the marine ecosystem.
Collapse
Affiliation(s)
- Anthony M Pagano
- Institute for Conservation Research, San Diego Zoo Global, San Diego, CA 92027, USA
| | - Terrie M Williams
- University of California, Santa Cruz, Department of Ecology and Evolutionary Biology, Santa Cruz, CA 95060, USA
| |
Collapse
|
12
|
Johnson AC, Reimer JR, Lunn NJ, Stirling I, McGeachy D, Derocher AE. Influence of sea ice dynamics on population energetics of Western Hudson Bay polar bears. CONSERVATION PHYSIOLOGY 2020; 8:coaa132. [PMID: 33408870 PMCID: PMC7772618 DOI: 10.1093/conphys/coaa132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 10/23/2020] [Accepted: 12/07/2020] [Indexed: 05/27/2023]
Abstract
The Arctic marine ecosystem has experienced extensive changes in sea ice dynamics, with significant effects on ice-dependent species such as polar bears (Ursus maritimus). We used annual estimates of the numbers of bears onshore in the core summering area, age/sex structure and body condition data to estimate population energy density and storage energy in Western Hudson Bay polar bears from 1985 to 2018. We examined intra-population variation in energetic patterns, temporal energetic trends and the relationship between population energetics and sea ice conditions. Energy metrics for most demographic classes declined over time in relation to earlier sea ice breakup, most significantly for solitary adult females and subadult males, suggesting their greater vulnerability to nutritional stress than other age/sex classes. Temporal declines in population energy metrics were related to earlier breakup and longer lagged open-water periods, suggesting multi-year effects of sea ice decline. The length of the open-water period ranged from 102 to 166 days and increased significantly by 9.9 days/decade over the study period. Total population energy density and storage energy were significantly lower when sea ice breakup occurred earlier and the lagged open-water period was longer. At the earliest breakup and a lagged open-water period of 180 days, population energy density was predicted to be 33% lower than our minimum estimated energy density and population storage energy was predicted to be 40% lower than the minimum estimated storage energy. Consequently, over the study, the total population energy density declined by 53% (mean: 3668 ± 386 MJ kg-1/decade) and total population storage energy declined by 56% (mean: 435900 ± 46770 MJ/decade). This study provides insights into ecological mechanisms linking population responses to sea ice decline and highlights the significance of maintaining long-term research programs.
Collapse
Affiliation(s)
- Amy C Johnson
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Jody R Reimer
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA
| | - Nicholas J Lunn
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Ian Stirling
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - David McGeachy
- Environment and Climate Change Canada, CW-422 Biological Sciences Building, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| |
Collapse
|
13
|
Laidre KL, Atkinson SN, Regehr EV, Stern HL, Born EW, Wiig Ø, Lunn NJ, Dyck M, Heagerty P, Cohen BR. Transient benefits of climate change for a high-Arctic polar bear (Ursus maritimus) subpopulation. GLOBAL CHANGE BIOLOGY 2020; 26:6251-6265. [PMID: 32964662 DOI: 10.1111/gcb.15286] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
Kane Basin (KB) is one of the world's most northerly polar bear (Ursus maritimus) subpopulations, where bears have historically inhabited a mix of thick multiyear and annual sea ice year-round. Currently, KB is transitioning to a seasonally ice-free region because of climate change. This ecological shift has been hypothesized to benefit polar bears in the near-term due to thinner ice with increased biological production, although this has not been demonstrated empirically. We assess sea-ice changes in KB together with changes in polar bear movements, seasonal ranges, body condition, and reproductive metrics obtained from capture-recapture (physical and genetic) and satellite telemetry studies during two study periods (1993-1997 and 2012-2016). The annual cycle of sea-ice habitat in KB shifted from a year-round ice platform (~50% coverage in summer) in the 1990s to nearly complete melt-out in summer (<5% coverage) in the 2010s. The mean duration between sea-ice retreat and advance increased from 109 to 160 days (p = .004). Between the 1990s and 2010s, adult female (AF) seasonal ranges more than doubled in spring and summer and were significantly larger in all months. Body condition scores improved for all ages and both sexes. Mean litter sizes of cubs-of-the-year (C0s) and yearlings (C1s), and the number of C1s per AF, did not change between decades. The date of spring sea-ice retreat in the previous year was positively correlated with C1 litter size, suggesting smaller litters following years with earlier sea-ice breakup. Our study provides evidence for range expansion, improved body condition, and stable reproductive performance in the KB polar bear subpopulation. These changes, together with a likely increasing subpopulation abundance, may reflect the shift from thick, multiyear ice to thinner, seasonal ice with higher biological productivity. The duration of these benefits is unknown because, under unmitigated climate change, continued sea-ice loss is expected to eventually have negative demographic and ecological effects on all polar bears.
Collapse
Affiliation(s)
- Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
- Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Stephen N Atkinson
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU, Canada
| | - Eric V Regehr
- 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
| | - Erik W Born
- Greenland Institute of Natural Resources, Nuuk, Greenland
| | - Øystein Wiig
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Nicholas J Lunn
- Environment and Climate Change Canada, University of Alberta, Edmonton, AB, Canada
| | - Markus Dyck
- Wildlife Research Section, Department of Environment, Government of Nunavut, Igloolik, NU, Canada
| | - Patrick Heagerty
- Department of Biostatistics, University of Washington, Seattle, WA, USA
| | - Benjamin R Cohen
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
| |
Collapse
|
14
|
Florko KRN, Thiemann GW, Bromaghin JF. Drivers and consequences of apex predator diet composition in the Canadian Beaufort Sea. Oecologia 2020; 194:51-63. [PMID: 32897468 DOI: 10.1007/s00442-020-04747-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
Polar bears (Ursus maritimus) rely on annual sea ice as their primary habitat for hunting marine mammal prey. Given their long lifespan, wide geographic distribution, and position at the top of the Arctic marine food web, the diet composition of polar bears can provide insights into temporal and spatial ecosystem dynamics related to climate-mediated sea ice loss. Polar bears with the greatest ecological constraints on diet composition may be most vulnerable to climate-related changes in ice conditions and prey availability. We used quantitative fatty acid signature analysis (QFASA) to estimate the diets of polar bears (n = 419) in two western Canadian Arctic subpopulations (Northern Beaufort Sea and Southern Beaufort Sea) from 1999 to 2015. Polar bear diets were dominated by ringed seal (Pusa hispida), with interannual, seasonal, age- and sex-specific variation. Foraging area and sea ice conditions also affected polar bear diet composition. Most variation in bear diet was explained by longitude, reflecting spatial variation in prey availability. Sea ice conditions (extent, thickness, and seasonal duration) declined throughout the study period, and date of sea ice break-up in the preceding spring was positively correlated with female body condition and consumption of beluga whale (Delphinapterus leucas), suggesting that bears foraged on beluga whales during entrapment events. Female body condition was positively correlated with ringed seal consumption, and negatively correlated with bearded seal consumption. This study provides insights into the complex relationships between declining sea ice habitat and the diet composition and foraging success of a wide-ranging apex predator.
Collapse
Affiliation(s)
- Katie R N Florko
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Gregory W Thiemann
- Faculty of Environmental Studies, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Jeffrey F Bromaghin
- Alaska Science Center, U.S. Geological Survey, 4210 University Drive, Anchorage, AK, 99508, USA
| |
Collapse
|
15
|
|
16
|
Pagano AM, Atwood TC, Durner GM, Williams TM. The seasonal energetic landscape of an apex marine carnivore, the polar bear. Ecology 2020; 101:e02959. [DOI: 10.1002/ecy.2959] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/22/2019] [Accepted: 11/12/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Anthony M. Pagano
- U.S. Geological SurveyAlaska Science Center4210 University Drive Anchorage Alaska99508USA
- Department of Ecology & Evolutionary Biology University of California Santa Cruz 130 McAllister Way Santa Cruz California95060USA
| | - Todd C. Atwood
- U.S. Geological SurveyAlaska Science Center4210 University Drive Anchorage Alaska99508USA
| | - George M. Durner
- U.S. Geological SurveyAlaska Science Center4210 University Drive Anchorage Alaska99508USA
| | - Terrie M. Williams
- Department of Ecology & Evolutionary Biology University of California Santa Cruz 130 McAllister Way Santa Cruz California95060USA
| |
Collapse
|
17
|
Blévin P, Aars J, Andersen M, Blanchet MA, Hanssen L, Herzke D, Jeffreys RM, Nordøy ES, Pinzone M, de la Vega C, Routti H. Pelagic vs Coastal-Key Drivers of Pollutant Levels in Barents Sea Polar Bears with Contrasted Space-Use Strategies. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:985-995. [PMID: 31823610 DOI: 10.1021/acs.est.9b04626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In the Barents Sea, pelagic and coastal polar bears are facing various ecological challenges that may explain the difference in their pollutant levels. We measured polychlorinated biphenyls, organochlorine pesticides, polybrominated diphenyl ethers in fat, and perfluoroalkyl substances in plasma in pelagic and coastal adult female polar bears with similar body condition. We studied polar bear feeding habits with bulk stable isotope ratios of carbon and nitrogen. Nitrogen isotopes of amino acids were used to investigate their trophic position. We studied energy expenditure by estimating field metabolic rate using telemetry data. Annual home range size was determined, and spatial gradients in pollutants were explored using latitude and longitude centroid positions of polar bears. Pollutant levels were measured in harp seals from the Greenland Sea and White Sea-Barents Sea as a proxy for a West-East gradient of pollutants in polar bear prey. We showed that pelagic bears had higher pollutant loads than coastal bears because (1) they feed on a higher proportion of marine and higher trophic level prey, (2) they have higher energy requirements and higher prey consumption, (3) they forage in the marginal ice zones, and (4) they feed on prey located closer to pollutant emission sources/transport pathways.
Collapse
Affiliation(s)
- Pierre Blévin
- Norwegian Polar Institute, Fram Centre , Tromsø 9296 , Norway
| | - Jon Aars
- Norwegian Polar Institute, Fram Centre , Tromsø 9296 , Norway
| | - Magnus Andersen
- Norwegian Polar Institute, Fram Centre , Tromsø 9296 , Norway
| | | | - Linda Hanssen
- Norwegian Institute for Air Research, Fram Centre , Tromsø 9296 , Norway
| | - Dorte Herzke
- Norwegian Institute for Air Research, Fram Centre , Tromsø 9296 , Norway
| | - Rachel M Jeffreys
- School of Environmental Science , University of Liverpool , Liverpool L69 7ZX , United Kingdom
| | | | - Marianna Pinzone
- Laboratory of Oceanology, Department of Biology, Ecology & Evolution , University of Liège , Liège B-4000 , Belgium
| | - Camille de la Vega
- School of Environmental Science , University of Liverpool , Liverpool L69 7ZX , United Kingdom
| | - Heli Routti
- Norwegian Polar Institute, Fram Centre , Tromsø 9296 , Norway
| |
Collapse
|
18
|
Sonne C, Alstrup AKO, Dietz R, Ok YS, Ciesielski TM, Jenssen BM. Aviation, melting sea-ice and polar bears. ENVIRONMENT INTERNATIONAL 2019; 133:105279. [PMID: 31671313 DOI: 10.1016/j.envint.2019.105279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 10/18/2019] [Accepted: 10/18/2019] [Indexed: 06/10/2023]
Abstract
On 11 May 2019, the Mauna Loa, Hawaii, Earth System Research Laboratory reported the highest CO2 concentration in human meteorological history. Continuing CO2 rise will devastate ecosystems, and ice dependent species like polar bears ultimately will disappear. Commercial aviation is presently a relatively small CO2 contributor, but this CO2 intensive mode of transportation is projected to increase greatly. Scientists and conservationists are often among the most frequent of flyers, despite their recognition that emissions must be reduced. Here we illustrate the carbon footprint of air travel in terms of its impact on the sea ice habitat necessary for polar bear persistence, and suggest our colleagues reduce their air travel where-ever possible. Each metric ton of CO2 emitted melts ~3 m2 of arctic summer sea ice, and current air travel melts over 5000 m2 each year. Each scientist making the short flight from Copenhagen to Oslo to join an IUCN polar bear meeting will melt ~1 m2 of Arctic summer sea-ice. Annually hundreds of scientists and conservationists make frequent flights of much greater distances for AMAP, CAFF, IUCN, and other conservation related meetings. Much of this travel could be avoided with better planning and employing internet linkages for remote participation. When air travel, such as for necessary fieldwork, cannot be easily substituted by Web linkage, we all should search for routes and carriers allowing the lowest CO2 emissions. We encourage all of our colleagues to join 'No Fly Climate Sci' to show their commitment to CO2 reduction and learn more about doing so. As scientists, if we are serious about preserving polar bears and their Arctic sea ice habitat, we need to walk the talk and show an example for the rest of society by significantly reducing our air travel.
Collapse
Affiliation(s)
- Christian Sonne
- Aarhus University, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark.
| | - Aage K O Alstrup
- Aarhus University Hospital, Department of Nuclear Medicine and PET Center, Palle Juul-Jensens Boulevard 99, DK-8200 Aarhus N, Denmark
| | - Rune Dietz
- Aarhus University, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark
| | - Yong Sik Ok
- Korea Biochar Research Center, Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Tomasz Maciej Ciesielski
- Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, NO-7491 Trondheim, Norway
| | - Bjørn Munro Jenssen
- Aarhus University, Department of Bioscience, Arctic Research Centre (ARC), Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde, Denmark; Aarhus University Hospital, Department of Nuclear Medicine and PET Center, Palle Juul-Jensens Boulevard 99, DK-8200 Aarhus N, Denmark
| |
Collapse
|
19
|
Post E, Alley RB, Christensen TR, Macias-Fauria M, Forbes BC, Gooseff MN, Iler A, Kerby JT, Laidre KL, Mann ME, Olofsson J, Stroeve JC, Ulmer F, Virginia RA, Wang M. The polar regions in a 2°C warmer world. SCIENCE ADVANCES 2019; 5:eaaw9883. [PMID: 31840060 PMCID: PMC6892626 DOI: 10.1126/sciadv.aaw9883] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 09/26/2019] [Indexed: 05/21/2023]
Abstract
Over the past decade, the Arctic has warmed by 0.75°C, far outpacing the global average, while Antarctic temperatures have remained comparatively stable. As Earth approaches 2°C warming, the Arctic and Antarctic may reach 4°C and 2°C mean annual warming, and 7°C and 3°C winter warming, respectively. Expected consequences of increased Arctic warming include ongoing loss of land and sea ice, threats to wildlife and traditional human livelihoods, increased methane emissions, and extreme weather at lower latitudes. With low biodiversity, Antarctic ecosystems may be vulnerable to state shifts and species invasions. Land ice loss in both regions will contribute substantially to global sea level rise, with up to 3 m rise possible if certain thresholds are crossed. Mitigation efforts can slow or reduce warming, but without them northern high latitude warming may accelerate in the next two to four decades. International cooperation will be crucial to foreseeing and adapting to expected changes.
Collapse
Affiliation(s)
- Eric Post
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA 95616, USA
| | - Richard B. Alley
- Department of Geosciences, and Earth and Environmental Systems Institute, The Pennsylvania State University, University Park, PA 16802, USA
| | - Torben R. Christensen
- Department of Bioscience, Arctic Research Centre, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Marc Macias-Fauria
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
| | - Bruce C. Forbes
- Arctic Centre, University of Lapland, Box 122, FI-96101 Rovaniemi, Finland
| | - Michael N. Gooseff
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80303, USA
| | - Amy Iler
- Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL 60022, USA
| | - Jeffrey T. Kerby
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, Davis, CA 95616, USA
- Neukom Institute for Computational Science, Institute of Arctic Studies, and Environmental Studies Program, Dartmouth College, Hanover, NH 03755, USA
| | - Kristin L. Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105, USA
| | - Michael E. Mann
- Department of Meteorology and Atmospheric Science and Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA
| | - Johan Olofsson
- Department of Ecology and Environmental Science, Umeå University, S-901 87 Umeå, Sweden
| | - Julienne C. Stroeve
- University College London, Bloomsbury, London, UK
- National Snow and Ice Data Center, Boulder, CO 80303, USA
| | - Fran Ulmer
- Chair, U.S. Arctic Research Commission, 420 L Street, Suite 315 Anchorage, AK 99501, USA
- Chair, U.S. Artic Research Commission, 4350 N. Fairfax Drive, Suite 510, Arlington, VA 22203, USA
- Belfer Center for Science and International Affairs John F. Kennedy School of Government, Harvard University, Cambridge, MA 02138, USA
| | - Ross A. Virginia
- Institute of Arctic Studies, and Environmental Studies Program, Dartmouth College, Hanover, NH 03755, USA
| | - Muyin Wang
- Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA
- National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory, Seattle, WA 98115, USA
| |
Collapse
|
20
|
Reimer JR, Mangel M, Derocher AE, Lewis MA. Modeling optimal responses and fitness consequences in a changing Arctic. GLOBAL CHANGE BIOLOGY 2019; 25:3450-3461. [PMID: 31077520 DOI: 10.1111/gcb.14681] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 04/29/2019] [Indexed: 06/09/2023]
Abstract
Animals must balance a series of costs and benefits while trying to maximize their fitness. For example, an individual may need to choose how much energy to allocate to reproduction versus growth, or how much time to spend on vigilance versus foraging. Their decisions depend on complex interactions between environmental conditions, behavioral plasticity, reproductive biology, and energetic demands. As animals respond to novel environmental conditions caused by climate change, the optimal decisions may shift. Stochastic dynamic programming provides a flexible modeling framework with which to explore these trade-offs, but this method has not yet been used to study possible changes in optimal trade-offs caused by climate change. We created a stochastic dynamic programming model capturing trade-off decisions required by an individual adult female polar bear (Ursus maritimus) as well as the fitness consequences of her decisions. We predicted optimal foraging decisions throughout her lifetime as well as the energetic thresholds below which it is optimal for her to abandon a reproductive attempt. To explore the effects of climate change, we shortened the spring feeding period by up to 3 weeks, which led to predictions of riskier foraging behavior and higher reproductive thresholds. The resulting changes in fitness may be interpreted as a best-case scenario, where bears adapt instantaneously and optimally to new environmental conditions. If the spring feeding period was reduced by 1 week, her expected fitness declined by 15%, and if reduced by 3 weeks, expected fitness declined by 68%. This demonstrates an effective way to explore a species' optimal response to a changing landscape of costs and benefits and highlights the fact that small annual effects can result in large cumulative changes in expected lifetime fitness.
Collapse
Affiliation(s)
- Jody R Reimer
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
| | - Marc Mangel
- Institute of Marine Sciences and Department of Applied Mathematics and Statistics, University of California, Santa Cruz, Santa Cruz, California
- Department of Biology, University of Bergen, Bergen, Norway
| | - Andrew E Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Mark A Lewis
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Mathematical and Statistical Sciences, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
21
|
Durner GM, Douglas DC, Atwood TC. Are polar bear habitat resource selection functions developed from 1985-1995 data still useful? Ecol Evol 2019; 9:8625-8638. [PMID: 31410267 PMCID: PMC6686286 DOI: 10.1002/ece3.5401] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 05/20/2019] [Accepted: 05/28/2019] [Indexed: 02/04/2023] Open
Abstract
Greenhouse-gas-induced warming in the Arctic has caused declines in sea ice extent and changed its composition, raising concerns by all circumpolar nations for polar bear conservation.Negative impacts have been observed in three well-studied polar bear subpopulations. Most subpopulations, however, receive little or no direct monitoring, hence, resource selection functions (RSF) may provide a useful proxy of polar bear distributions. However, the efficacy of RSFs constructed from past data, that is, reference RSFs, may be degraded under contemporary conditions, especially in a rapidly changing environment.We assessed published Arctic-wide reference RSFs using tracking data from adult female polar bears captured in the Beaufort Sea. We compared telemetry-derived seasonal distributions of polar bears to RSF-defined optimal sea ice habitat during the period of RSF model development, 1985-1995, and two subsequent periods with diminished sea ice: 1996-2006 and 2007-2016. From these comparisons, we assessed the applicability of the reference RSFs for contemporary polar bear conservation.In the two decades following the 1985-1995 reference period, use and availability of optimal habitat by polar bears declined during the ice melt, ice minimum, and ice growth seasons. During the ice maximum season (i.e., winter), polar bears used the best habitat available, which changed relatively little across the three decades of study. During the ice melt, ice minimum, and ice growth seasons, optimal habitat in areas used by polar bears decreased and was displaced north and east of the Alaska Beaufort Sea coast. As optimal habitat diminished in these seasons, polar bears expanded their range and occupied greater areas of suboptimal habitat.Synthesis and applications: Sea ice declines due to climate change continue to challenge polar bears and their conservation. The distribution of Southern Beaufort Sea polar bears remained similar during the ice maximum season, so the reference RSFs developed from data collected >20 years ago continue to accurately model their winter distribution. In contrast, reference RSFs for the ice transitional and minimum seasons showed diminished predictive efficacy but were useful in revealing that contemporary polar bears have been increasingly forced to use suboptimal habitats during those seasons.
Collapse
Affiliation(s)
| | | | - Todd C. Atwood
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaskaUSA
| |
Collapse
|
22
|
Space use patterns affect stable isotopes of polar bears (Ursus maritimus) in the Beaufort Sea. Polar Biol 2019. [DOI: 10.1007/s00300-019-02546-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
23
|
Macias-Fauria M, Post E. Effects of sea ice on Arctic biota: an emerging crisis discipline. Biol Lett 2019; 14:rsbl.2017.0702. [PMID: 29563280 DOI: 10.1098/rsbl.2017.0702] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/22/2018] [Indexed: 11/12/2022] Open
Abstract
The rapid decline in Arctic sea ice (ASI) extent, area and volume during recent decades is occurring before we can understand many of the mechanisms through which ASI interacts with biological processes both at sea and on land. As a consequence, our ability to predict and manage the effects of this enormous environmental change is limited, making this a crisis discipline Here, we propose a framework to study these effects, defining direct effects as those acting on life-history events of Arctic biota, and indirect effects, where ASI acts upon biological systems through chains of events, normally involving other components of the physical system and/or biotic interactions. Given the breadth and complexity of ASI's effects on Arctic biota, Arctic research requires a truly multidisciplinary approach to address this issue. In the absence of effective global efforts to tackle anthropogenic global warming, ASI will likely continue to decrease, compromising the conservation of many ASI-related taxonomic groups and ecosystems. Mitigation actions will rely heavily on the knowledge acquired on the mechanisms and components involved with the biological effects of ASI.
Collapse
Affiliation(s)
- Marc Macias-Fauria
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
| | - Eric Post
- Department of Wildlife, Fish and Conservation Biology, University of California, Davis, CA 95616-8571, USA
| |
Collapse
|
24
|
Pagano AM, Williams TM. Estimating the energy expenditure of free-ranging polar bears using tri-axial accelerometers: A validation with doubly labeled water. Ecol Evol 2019; 9:4210-4219. [PMID: 31015999 PMCID: PMC6468055 DOI: 10.1002/ece3.5053] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Revised: 02/13/2019] [Accepted: 02/19/2019] [Indexed: 01/27/2023] Open
Abstract
Measures of energy expenditure can be used to inform animal conservation and management, but methods for measuring the energy expenditure of free-ranging animals have a variety of limitations. Advancements in biologging technologies have enabled the use of dynamic body acceleration derived from accelerometers as a proxy for energy expenditure. Although dynamic body acceleration has been shown to strongly correlate with oxygen consumption in captive animals, it has been validated in only a few studies on free-ranging animals. Here, we use relationships between oxygen consumption and overall dynamic body acceleration in resting and walking polar bears Ursus maritimus and published values for the costs of swimming in polar bears to estimate the total energy expenditure of 6 free-ranging polar bears that were primarily using the sea ice of the Beaufort Sea. Energetic models based on accelerometry were compared to models of energy expenditure on the same individuals derived from doubly labeled water methods. Accelerometer-based estimates of energy expenditure on average predicted total energy expenditure to be 30% less than estimates derived from doubly labeled water. Nevertheless, accelerometer-based measures of energy expenditure strongly correlated (r 2 = 0.70) with measures derived from doubly labeled water. Our findings highlight the strengths and limitations in dynamic body acceleration as a measure of total energy expenditure while also further supporting its use as a proxy for instantaneous, detailed energy expenditure in free-ranging animals.
Collapse
Affiliation(s)
- Anthony M. Pagano
- Alaska Science CenterU.S. Geological SurveyAnchorageAlaska
- Present address:
Institute for Conservation ResearchSan Diego Zoo GlobalSan DiegoCalifornia
| | - Terrie M. Williams
- Department of Ecology & Evolutionary BiologyUniversity of California, Santa CruzSanta CruzCalifornia
| |
Collapse
|
25
|
Pagano AM, Carnahan AM, Robbins CT, Owen MA, Batson T, Wagner N, Cutting A, Nicassio-Hiskey N, Hash A, Williams TM. Energetic costs of locomotion in bears: is plantigrade locomotion energetically economical? ACTA ACUST UNITED AC 2018; 221:221/12/jeb175372. [PMID: 29921569 DOI: 10.1242/jeb.175372] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 04/21/2018] [Indexed: 02/05/2023]
Abstract
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. To evaluate whether polar bears are representative of terrestrial ursids or distinctly uneconomical walkers, this study measured the mass-specific metabolism, overall dynamic body acceleration, and gait kinematics of polar bears and grizzly bears (Ursus arctos) trained to rest and walk on a treadmill. At routine walking speeds, we found polar bears and grizzly bears exhibited similar costs of locomotion and gait kinematics, but differing measures of overall dynamic body acceleration. Minimum cost of transport while walking in the two species (2.21 J kg-1 m-1) was comparable to predictions for similarly sized quadrupedal mammals, but these costs doubled (4.42 J kg-1 m-1) at speeds ≥5.4 km h-1 Similar to humans, another large plantigrade mammal, bears appear to exhibit a greater economy while moving at slow speeds.
Collapse
Affiliation(s)
- Anthony M Pagano
- US Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, AK 99508, USA .,Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Anthony M Carnahan
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Charles T Robbins
- School of the Environment and School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Megan A Owen
- Institute for Conservation Research, San Diego Zoo Global, San Diego, CA 92027, USA
| | | | - Nate Wagner
- San Diego Zoo Global, San Diego, CA 92027, USA
| | | | | | - Amy Hash
- Oregon Zoo, Portland, OR 97221, USA
| | - Terrie M Williams
- Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| |
Collapse
|
26
|
Harvey JA, van den Berg D, Ellers J, Kampen R, Crowther TW, Roessingh P, Verheggen B, Nuijten RJM, Post E, Lewandowsky S, Stirling I, Balgopal M, Amstrup SC, Mann ME. Internet Blogs, Polar Bears, and Climate-Change Denial by Proxy. Bioscience 2018; 68:281-287. [PMID: 29662248 PMCID: PMC5894087 DOI: 10.1093/biosci/bix133] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Increasing surface temperatures, Arctic sea-ice loss, and other evidence of anthropogenic global warming (AGW) are acknowledged by every major scientific organization in the world. However, there is a wide gap between this broad scientific consensus and public opinion. Internet blogs have strongly contributed to this consensus gap by fomenting misunderstandings of AGW causes and consequences. Polar bears (Ursus maritimus) have become a "poster species" for AGW, making them a target of those denying AGW evidence. Here, focusing on Arctic sea ice and polar bears, we show that blogs that deny or downplay AGW disregard the overwhelming scientific evidence of Arctic sea-ice loss and polar bear vulnerability. By denying the impacts of AGW on polar bears, bloggers aim to cast doubt on other established ecological consequences of AGW, aggravating the consensus gap. To counter misinformation and reduce this gap, scientists should directly engage the public in the media and blogosphere.
Collapse
Affiliation(s)
- Jeffrey A Harvey
- Department of Terrestrial Ecology at the Netherlands Institute of Ecology, in Wageningen. JAH
| | - Daphne van den Berg
- Department of Ecological Sciences–Animal Ecology at the VU University Amsterdam, in The Netherlands
| | - Jacintha Ellers
- Department of Ecological Sciences–Animal Ecology at the VU University Amsterdam, in The Netherlands
| | | | - Thomas W Crowther
- Department of Terrestrial Ecology at the Netherlands Institute of Ecology, in Wageningen, and with the Institute of Integrative Biology, in Zürich, Switzerland
| | - Peter Roessingh
- Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam, in The Netherlands
| | | | - Rascha J M Nuijten
- Department of Animal Ecology at Netherlands Institute of Ecology, in Wageningen
| | - Eric Post
- Department of Wildlife, Fish, and Conservation Biology at the University of California, Davis
| | - Stephan Lewandowsky
- School of Experimental Psychology and Cabot Institute at the University of Bristol, in the United Kingdom, and with CSIRO Oceans and Atmosphere, in Hobart, Tasmania, Australia
| | - Ian Stirling
- Wildlife Research Division of Environment and Climate Change Canada, and with the Department of Biological Sciences at the University of Alberta, in Edmonton, Canada
| | - Meena Balgopal
- Department of Biology at Colorado State University, in Fort Collins
| | - Steven C Amstrup
- Polar Bears International, in Bozeman, Montana, and with the Department of Zoology and Physiology at the University of Wyoming, in Laramie
| | - Michael E Mann
- Department of Meteorology and Atmospheric Science at Pennsylvania State University, in University Park
| |
Collapse
|
27
|
Tartu S, Aars J, Andersen M, Polder A, Bourgeon S, Merkel B, Lowther AD, Bytingsvik J, Welker JM, Derocher AE, Jenssen BM, Routti H. Choose Your Poison-Space-Use Strategy Influences Pollutant Exposure in Barents Sea Polar Bears. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:3211-3221. [PMID: 29363970 DOI: 10.1021/acs.est.7b06137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
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 (nitrogen and carbon stable isotopes, n = 116) between offshore and coastal space-use. Second, we investigated how HR, space-use, body condition, and diet were related to plasma concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) ( n = 113), perfluoroalkyl substances (PFASs; n = 92), and hydroxylated-PCBs ( n = 109). Offshore females were in better condition and had a more specialized diet than did coastal females. PCBs, OCPs, and hydroxylated-PCB concentrations were not related to space-use strategy, yet PCB concentrations increased with increasing latitude, and hydroxylated-PCB concentrations were positively related to HR size. PFAS concentrations were 30-35% higher in offshore bears compared to coastal bears and also increased eastward. On the basis of the results we conclude that space-use of Barents Sea female polar bears influences their pollutant exposure, in particular plasma concentrations of PFAS.
Collapse
Affiliation(s)
- Sabrina Tartu
- Norwegian Polar Institute , Fram Centre , Tromsø NO-9296 , Norway
| | - Jon Aars
- Norwegian Polar Institute , Fram Centre , Tromsø NO-9296 , Norway
| | - Magnus Andersen
- Norwegian Polar Institute , Fram Centre , Tromsø NO-9296 , Norway
| | - Anuschka Polder
- Norwegian University of Life Science , Campus Adamstua , Oslo NO-1432 , Norway
| | - Sophie Bourgeon
- UiT-The Arctic University of Norway , Department of Arctic and Marine Biology , Tromsø NO-9010 , Norway
| | - Benjamin Merkel
- Norwegian Polar Institute , Fram Centre , Tromsø NO-9296 , Norway
| | - Andrew D Lowther
- Norwegian Polar Institute , Fram Centre , Tromsø NO-9296 , Norway
| | | | - Jeffrey M Welker
- Department of Biological Sciences , University of Alaska-Anchorage , Anchorage , Alaska 99508 , United States
- Department of Arctic Technology , University Center in Svalbard , Longyearbyen, Svalbard NO-9171 , Norway
| | - Andrew E Derocher
- Department of Biological Sciences , University of Alberta , Edmonton T6G 2R3 , Canada
| | - Bjørn Munro Jenssen
- Department of Arctic Technology , University Center in Svalbard , Longyearbyen, Svalbard NO-9171 , Norway
- Department of Biology , Norwegian University of Science and Technology , Trondheim NO-7491 , Norway
| | - Heli Routti
- Norwegian Polar Institute , Fram Centre , Tromsø NO-9296 , Norway
| |
Collapse
|
28
|
Affiliation(s)
- John P Whiteman
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA.
| |
Collapse
|
29
|
Pagano AM, Durner GM, Rode KD, Atwood TC, Atkinson SN, Peacock E, Costa DP, Owen MA, Williams TM. High-energy, high-fat lifestyle challenges an Arctic apex predator, the polar bear. Science 2018; 359:568-572. [DOI: 10.1126/science.aan8677] [Citation(s) in RCA: 92] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 12/19/2017] [Indexed: 11/02/2022]
|
30
|
Guglielmi G. Polar bears are wasting away in a changing climate. Nature 2018. [DOI: 10.1038/d41586-018-01501-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|