1
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Gissi E, Schiebinger L, Hadly EA, Crowder LB, Santoleri R, Micheli F. Exploring climate-induced sex-based differences in aquatic and terrestrial ecosystems to mitigate biodiversity loss. Nat Commun 2023; 14:4787. [PMID: 37587108 PMCID: PMC10432542 DOI: 10.1038/s41467-023-40316-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 07/14/2023] [Indexed: 08/18/2023] Open
Affiliation(s)
- Elena Gissi
- Oceans Department, Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, 93950, USA.
- National Research Council, Institute of Marine Science, CNR ISMAR, Arsenale, Tesa 104 - Castello 2737/F, 30122, Venice, Italy.
- National Biodiversity Future Center, Palermo, 90133, Italy.
| | - Londa Schiebinger
- History of Science, Gendered Innovations in Science, Health & Medicine, Engineering and Environment, Stanford University, Stanford, CA, 94305, USA
| | - Elizabeth A Hadly
- Department of Biology, Stanford University, Stanford, 94305, CA, USA
- Stanford Woods Institute for The Environment, Stanford University, Stanford, 94305, CA, USA
- Center for Innovation in Global Health, Stanford University, Stanford, 94305, CA, USA
| | - Larry B Crowder
- Oceans Department, Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, 93950, USA
- Stanford Woods Institute for The Environment, Stanford University, Stanford, 94305, CA, USA
| | - Rosalia Santoleri
- National Research Council, Institute of Marine Science, CNR ISMAR, Arsenale, Tesa 104 - Castello 2737/F, 30122, Venice, Italy
| | - Fiorenza Micheli
- Oceans Department, Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, 93950, USA
- Stanford Woods Institute for The Environment, Stanford University, Stanford, 94305, CA, USA
- Stanford Center for Ocean Solutions, 120 Ocean View Blvd, Pacific Grove, CA, 93950, USA
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2
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Robeck T, Katsumata E, Arai K, Montano G, Schmitt T, DiRocco S, Steinman KJ. Growth, maturity, reproduction, and life expectancy in ex-situ pacific walruses (Odobenus rosmarus divergens). BMC ZOOL 2022; 7:57. [PMID: 37170158 PMCID: PMC10127427 DOI: 10.1186/s40850-022-00158-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 11/13/2022] [Indexed: 12/09/2022] Open
Abstract
Abstract
Background
Pacific walruses are found in Arctic regions of the Chukchi and Bering Sea where rapid changes in environmental conditions resulting in loss of sea ice are occurring. Therefore, accurate life history data are crucial for species management plans and longitudinal data collected over the lives of individual walruses housed in zoos and aquaria provide otherwise difficult to obtain biological information.
Results
While similar at birth, Gompertz regression curves indicated that males grew faster than females (p < 0.0001) in weight (99 kg vs 57.6 kg/y) and length (26.9 cm vs 26.3 cm/y) with physical differences being detected by age 3 for weight and age 7 for length. Males reached adult weight at 13.5 ± 3.3 y and females by age 12.3 ± 2.3 y. The mean age at first ovulation and at first conception occurred at 8.8 y and 9.6 y. Greater than 75% of all conceptions and calving occurred between February and March and from May to June, respectively. Mean gestation lasted 423 d and false pregnancies lasted at least 169 d with a decrease (p < 0.05) in serum progesterone concentration between false pregnancy and pregnancy occurring within 6 months after ovulation. Based on these results, we estimated embryonic diapause to last from 120 to 139 days, and fetal growth last ~ 284 days. All males older than 8 y had an increase in serum testosterone and body weight that was highest in February and lowest in July. Overall, no differences were observed between male and female survival, with a mean (± SEM) life expectancy of 19.5 ± 1.5 y, respectively. Currently, the oldest male and female captive walruses are 40 and 43 y, respectively.
Conclusions
Data provided herein include details of life history characteristics of zoo and aquaria housed walruses that are useful for wild population recovery models. In particular, results on survivorship and the identification of the most vulnerable period for calf survival can help with model development and suggests that for recovery to occur birthing locations for this species must be protected.
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3
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Koch CW, Cooper LW, Woodland RJ, Grebmeier JM, Frey KE, Stimmelmayr R, Magen C, Brown TA. Female Pacific walruses (Odobenus rosmarus divergens) show greater partitioning of sea ice organic carbon than males: Evidence from ice algae trophic markers. PLoS One 2021; 16:e0255686. [PMID: 34411125 PMCID: PMC8376070 DOI: 10.1371/journal.pone.0255686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 07/21/2021] [Indexed: 11/25/2022] Open
Abstract
The expected reduction of ice algae with declining sea ice may prove to be detrimental to the Pacific Arctic ecosystem. Benthic organisms that rely on sea ice organic carbon (iPOC) sustain benthic predators such as the Pacific walrus (Odobenus rosmarus divergens). The ability to track the trophic transfer of iPOC is critical to understanding its value in the food web, but prior methods have lacked the required source specificity. We analyzed the H-Print index, based on biomarkers of ice algae versus phytoplankton contributions to organic carbon in marine predators, in Pacific walrus livers collected in 2012, 2014 and 2016 from the Northern Bering Sea (NBS) and Chukchi Sea. We paired these measurements with stable nitrogen isotopes (δ15N) to estimate trophic position. We observed differences in the contribution of iPOC in Pacific walrus diet between regions, sexes, and age classes. Specifically, the contribution of iPOC to the diet of Pacific walruses was higher in the Chukchi Sea (52%) compared to the NBS (30%). This regional difference is consistent with longer annual sea ice persistence in the Chukchi Sea. Within the NBS, the contribution of iPOC to walrus spring diet was higher in females (~45%) compared to males (~30%) for each year (p < 0.001), likely due to specific foraging behavior of females to support energetic demands associated with pregnancy and lactation. Within the Chukchi Sea, the iPOC contribution was similar between males and females, yet higher in juveniles than in adults. Despite differences in the origin of organic carbon fueling the system (sea ice versus pelagic derived carbon), the trophic position of adult female Pacific walruses was similar between the NBS and Chukchi Sea (3.2 and 3.5, respectively), supporting similar diets (i.e. clams). Given the higher quality of organic carbon from ice algae, the retreat of seasonal sea ice in recent decades may create an additional vulnerability for female and juvenile Pacific walruses and should be considered in management of the species.
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Affiliation(s)
- Chelsea W. Koch
- University of Maryland Center for Environmental Science, Solomons, Maryland, United States of America
- * E-mail:
| | - Lee W. Cooper
- University of Maryland Center for Environmental Science, Solomons, Maryland, United States of America
| | - Ryan J. Woodland
- University of Maryland Center for Environmental Science, Solomons, Maryland, United States of America
| | - Jacqueline M. Grebmeier
- University of Maryland Center for Environmental Science, Solomons, Maryland, United States of America
| | - Karen E. Frey
- Graduate School of Geography, Clark University, Worcester, Massachusetts, United States of America
| | - Raphaela Stimmelmayr
- North Slope Borough Department of Wildlife Management, Utqiaġvik, Alaska, United States of America
- Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, United States of America
| | - Cédric Magen
- University of Maryland Center for Environmental Science, Solomons, Maryland, United States of America
| | - Thomas A. Brown
- Scottish Association for Marine Science, Oban, Scotland, United Kingdom
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4
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Clark CT, Horstmann L, Misarti N. Evaluating tooth strontium and barium as indicators of weaning age in Pacific walruses. Methods Ecol Evol 2020; 11:1626-1638. [PMID: 33381293 PMCID: PMC7756818 DOI: 10.1111/2041-210x.13482] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 08/20/2020] [Indexed: 11/30/2022]
Abstract
Lactation length and weaning age provide important information about maternal investment, which can reflect the health and nutritional status of the mother, as well as broader reproductive strategies in mammals. Calcium-normalized strontium (Sr) and barium (Ba) concentrations in the growth layers of mammalian teeth differ for nursing animals and those consuming non-milk foods, thus can be used to estimate age-at-weaning. To date, this approach has been used only for terrestrial animals, and almost exclusively for primates.The goal of this study was to determine whether Sr and Ba concentrations in the cementum of Pacific walrus Odobenus rosmarus divergens teeth can be used to estimate weaning age. Teeth from 107 walruses were analysed using laser ablation inductively coupled plasma mass spectrometry, and calcium-normalized 88Sr and 137Ba concentrations were quantified.For most walruses, both Sr and Ba concentrations exhibited rapid changes in early life. Ba concentrations matched closely with expected patterns in the published literature, rapidly declining from high to low concentrations (typically from ~10 ppm to ~5 ppm). In contrast, Sr exhibited a pattern opposite to that presented in studies of terrestrial mammals, appearing nearly identical to Ba (typically declining from ~400 ppm to ~200 ppm). To explain these findings, we present conceptual models of the factors generating weaning signals in Sr and Ba for terrestrial mammals, as well as a new, hypothetical model for walruses. Both a visual and mathematical approach to weaning age estimation indicated a median weaning age of walruses at the end of the second year of life (in the second dark layer of the tooth cementum), with many walruses estimated to have weaned in their third year of life, and a smaller group weaning in their fourth or fifth year. This is later than expected, given a published estimate of walrus weaning at 18-24 months.These results do not conclusively support the use of tooth Sr and Ba for estimating weaning age in walruses, and further research is warranted to better understand the drivers of the observed patterns of Ba and Sr accumulation in walrus teeth.
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Affiliation(s)
- Casey T. Clark
- Joint Institute for the Study of Atmosphere and OceanUniversity of WashingtonSeattleWAUSA
- Cooperative Institute for Climate, Ocean, and Ecosystem StudiesUniversity of WashingtonSeattleWAUSA
| | - Lara Horstmann
- College of Fisheries and Ocean SciencesUniversity of Alaska FairbanksFairbanksAKUSA
| | - Nicole Misarti
- Water and Environmental Research CenterUniversity of Alaska FairbanksFairbanksAKUSA
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5
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A little SNP of this, a little SNP of that: The discovery of 116 single nucleotide polymorphism markers to enable the rapid identification of individual Pacific walrus (Odobenus rosmarus divergens). CONSERV GENET RESOUR 2020. [DOI: 10.1007/s12686-020-01156-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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6
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Beatty WS, Lemons PR, Sethi SA, Everett JP, Lewis CJ, Lynn RJ, Cook GM, Garlich-Miller JL, Wenburg JK. Panmixia in a sea ice-associated marine mammal: evaluating genetic structure of the Pacific walrus (Odobenus rosmarus divergens) at multiple spatial scales. J Mammal 2020. [DOI: 10.1093/jmammal/gyaa050] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AbstractThe kin structure of a species at relatively fine spatial scales impacts broad-scale patterns in genetic structure at the population level. However, kin structure rarely has been elucidated for migratory marine mammals. The Pacific walrus (Odobenus rosmarus divergens) exhibits migratory behavior linked to seasonal patterns in sea ice dynamics. Consequently, information on the spatial genetic structure of the subspecies, including kin structure, could aid wildlife managers in designing future studies to evaluate the impacts of sea ice loss on the subspecies. We sampled 8,303 individual walruses over a 5-year period and used 114 single-nucleotide polymorphisms to examine both broad-scale patterns in genetic structure and fine-scale patterns in relatedness. We did not detect any evidence of genetic structure at broad spatial scales, with low FST values (≤ 0.001) across all pairs of putative aggregations. To evaluate kin structure at fine spatial scales, we defined a walrus group as a cluster of resting individuals that were less than one walrus body length apart. We found weak evidence of kin structure at fine spatial scales, with 3.72% of groups exhibiting mean relatedness values greater than expected by chance, and a significantly higher overall observed mean value of relatedness within groups than expected by chance. Thus, the high spatiotemporal variation in the distribution of resources in the Pacific Arctic environment likely has favored a gregarious social system in Pacific walruses, with unrelated animals forming temporary associations.
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Affiliation(s)
- William S Beatty
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Patrick R Lemons
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Suresh A Sethi
- U.S. Geological Survey, New York Cooperative Fish and Wildlife Research Unit, Ithaca, NY, USA
| | - Jason P Everett
- U.S. Fish and Wildlife Service, Conservation Genetics Laboratory, Anchorage, AK, USA
| | - Cara J Lewis
- U.S. Fish and Wildlife Service, Conservation Genetics Laboratory, Anchorage, AK, USA
| | - Robert J Lynn
- U.S. Fish and Wildlife Service, Marine Mammals Management, Anchorage, AK, USA
| | - Geoffrey M Cook
- U.S. Fish and Wildlife Service, Conservation Genetics Laboratory, Anchorage, AK, USA
| | | | - John K Wenburg
- U.S. Fish and Wildlife Service, Conservation Genetics Laboratory, Anchorage, AK, USA
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7
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Clark CT, Horstmann L, Misarti N. Zinc concentrations in teeth of female walruses reflect the onset of reproductive maturity. CONSERVATION PHYSIOLOGY 2020; 8:coaa029. [PMID: 32308984 PMCID: PMC7154182 DOI: 10.1093/conphys/coaa029] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 02/26/2020] [Accepted: 03/06/2020] [Indexed: 05/27/2023]
Abstract
Age at maturity is an important parameter in many demographic models and, for some species, can be difficult to obtain using traditional methods. Incremental growth structures act as biological archives, recording information throughout an organism's life and possibly allowing for the reconstruction of life history events. Concentrations of zinc (Zn) in animal tissues are known to be linked to life history, physiology and reproduction and may be retained in incremental growth structures. This study reconstructed lifetime Zn concentrations in teeth (n = 93) of female Pacific walruses (Odobenus rosmarus divergens) collected from 1932-2016. Zn displayed a characteristic pattern of accumulation, with a change point marking the beginning of a lifelong, linear increase in Zn concentrations. We hypothesized that this change point marks the onset of reproductive maturity. The age at which the change point occurred (agecp) was estimated by counting tooth cementum growth layers. These estimates closely matched literature values of timing of first ovulation in female walruses. Total number of ovulations (estimated from ovary corpora counts from paired tooth/ovary specimens) was closely related to reproductive lifespan (total lifespan - agecp; R2 = 0.70). Further, agecp tracked changes in Pacific walrus population size as a proportion of carrying capacity, decreasing when the population was depleted by commercial hunting and peaking when carrying capacity was exceeded. This novel approach will aid walrus management, and is likely applicable to other species, offering a potentially powerful tool for research, management and conservation of wildlife populations.
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Affiliation(s)
- Casey T Clark
- Water and Environmental Research Center, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, AK 99775-5860, USA
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 2150 Koyukuk Drive, Fairbanks, AK 99775-7220, USA
- Joint Institute for the Study of Atmosphere and Ocean, University of Washington, 3737 Brooklyn Ave NE, Seattle, WA 98105
| | - Lara Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 2150 Koyukuk Drive, Fairbanks, AK 99775-7220, USA
| | - Nicole Misarti
- Water and Environmental Research Center, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, AK 99775-5860, USA
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8
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Mascarenhas R, Ruziska FM, Moreira EF, Campos AB, Loiola M, Reis K, Trindade-Silva AE, Barbosa FAS, Salles L, Menezes R, Veiga R, Coutinho FH, Dutilh BE, Guimarães PR, Assis APA, Ara A, Miranda JGV, Andrade RFS, Vilela B, Meirelles PM. Integrating Computational Methods to Investigate the Macroecology of Microbiomes. Front Genet 2020; 10:1344. [PMID: 32010196 PMCID: PMC6979972 DOI: 10.3389/fgene.2019.01344] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 12/09/2019] [Indexed: 12/15/2022] Open
Abstract
Studies in microbiology have long been mostly restricted to small spatial scales. However, recent technological advances, such as new sequencing methodologies, have ushered an era of large-scale sequencing of environmental DNA data from multiple biomes worldwide. These global datasets can now be used to explore long standing questions of microbial ecology. New methodological approaches and concepts are being developed to study such large-scale patterns in microbial communities, resulting in new perspectives that represent a significant advances for both microbiology and macroecology. Here, we identify and review important conceptual, computational, and methodological challenges and opportunities in microbial macroecology. Specifically, we discuss the challenges of handling and analyzing large amounts of microbiome data to understand taxa distribution and co-occurrence patterns. We also discuss approaches for modeling microbial communities based on environmental data, including information on biological interactions to make full use of available Big Data. Finally, we summarize the methods presented in a general approach aimed to aid microbiologists in addressing fundamental questions in microbial macroecology, including classical propositions (such as “everything is everywhere, but the environment selects”) as well as applied ecological problems, such as those posed by human induced global environmental changes.
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Affiliation(s)
| | - Flávia M Ruziska
- Institute of Biology, Federal University of Bahia, Salvador, Brazil
| | | | - Amanda B Campos
- Institute of Biology, Federal University of Bahia, Salvador, Brazil
| | - Miguel Loiola
- Institute of Biology, Federal University of Bahia, Salvador, Brazil
| | - Kaike Reis
- Chemical Engineering Department, Polytechnic School of Federal University of Bahia, Salvador, Brazil
| | - Amaro E Trindade-Silva
- Institute of Biology, Federal University of Bahia, Salvador, Brazil.,Department of Ecology, Biosciences Institute, University of Sao Paulo, Sao Paulo, Brazil
| | | | - Lucas Salles
- Institute of Geology, Federal University of Bahia, Salvador, Brazil
| | - Rafael Menezes
- Department of Ecology, Biosciences Institute, University of Sao Paulo, Sao Paulo, Brazil.,Institute of Physics, Federal University of Bahia, Salvador, Brazil
| | - Rafael Veiga
- Center of Data and Knowledge Integration for Health (CIDACS), Instituto Gonçalo Muniz, Fundação Oswaldo Cruz, Brazil
| | - Felipe H Coutinho
- Evolutionary Genomics Group, Departamento de Producción Vegetal y Microbiología, Universidad Miguel Hernández de Elche, San Juan de Alicante, Spain
| | - Bas E Dutilh
- Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, Netherlands.,Centre for Molecular and Biomolecular Informatics, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Paulo R Guimarães
- Department of Ecology, Biosciences Institute, University of Sao Paulo, Butantã, Brazil
| | - Ana Paula A Assis
- Department of Ecology, Biosciences Institute, University of Sao Paulo, Butantã, Brazil
| | - Anderson Ara
- Institute of Mathematics, Federal University of Bahia, Salvador, Brazil
| | - José G V Miranda
- Institute of Physics, Federal University of Bahia, Salvador, Brazil
| | - Roberto F S Andrade
- Institute of Physics, Federal University of Bahia, Salvador, Brazil.,Center of Data and Knowledge Integration for Health (CIDACS), Instituto Gonçalo Muniz, Fundação Oswaldo Cruz, Brazil
| | - Bruno Vilela
- Institute of Biology, Federal University of Bahia, Salvador, Brazil
| | - Pedro Milet Meirelles
- Institute of Biology, Federal University of Bahia, Salvador, Brazil.,Department of Ecology, Biosciences Institute, University of Sao Paulo, Sao Paulo, Brazil
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9
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Sipunculan fauna in the Pacific Arctic region: a significant component of benthic infaunal communities. Polar Biol 2018. [DOI: 10.1007/s00300-017-2179-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Udevitz MS, Jay CV, Taylor RL, Fischbach AS, Beatty WS, Noren SR. Forecasting consequences of changing sea ice availability for Pacific walruses. Ecosphere 2017. [DOI: 10.1002/ecs2.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Mark S. Udevitz
- Alaska Science Center, U.S. Geological Survey 4210 University Drive Anchorage Alaska 99508 USA
| | - Chadwick V. Jay
- Alaska Science Center, U.S. Geological Survey 4210 University Drive Anchorage Alaska 99508 USA
| | - Rebecca L. Taylor
- Alaska Science Center, U.S. Geological Survey 4210 University Drive Anchorage Alaska 99508 USA
| | - Anthony S. Fischbach
- Alaska Science Center, U.S. Geological Survey 4210 University Drive Anchorage Alaska 99508 USA
| | - William S. Beatty
- U.S. Fish and Wildlife Service, Marine Mammals Management 1011 East Tudor Road Anchorage Alaska 99503 USA
| | - Shawn R. Noren
- Institute of Marine Science University of California, Santa Cruz 100 Shaffer Road Santa Cruz California 95060 USA
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11
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Evaluation of a method using survey counts and tag data to estimate the number of Pacific walruses (Odobenus rosmarus divergens) using a coastal haulout in northwestern Alaska. Polar Biol 2017. [DOI: 10.1007/s00300-016-2060-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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12
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Jay CV, Taylor RL, Fischbach AS, Udevitz MS, Beatty WS. Walrus haul-out and in water activity levels relative to sea ice availability in the Chukchi Sea. J Mammal 2017. [DOI: 10.1093/jmammal/gyw195] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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13
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Hinke JT, Trivelpiece SG, Trivelpiece WZ. Variable vital rates and the risk of population declines in Adélie penguins from the Antarctic Peninsula region. Ecosphere 2017. [DOI: 10.1002/ecs2.1666] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Jefferson T. Hinke
- Antarctic Ecosystem Research Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California 92037 USA
| | - Susan G. Trivelpiece
- Antarctic Ecosystem Research Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California 92037 USA
| | - Wayne Z. Trivelpiece
- Antarctic Ecosystem Research Division Southwest Fisheries Science Center National Marine Fisheries Service National Oceanic and Atmospheric Administration La Jolla California 92037 USA
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14
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15
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Winer JN, Arzi B, Leale DM, Kass PH, Verstraete FJM. Dental and Temporomandibular Joint Pathology of the Walrus (Odobenus rosmarus). J Comp Pathol 2016; 155:242-253. [PMID: 27530539 DOI: 10.1016/j.jcpa.2016.07.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 06/28/2016] [Accepted: 07/03/2016] [Indexed: 11/19/2022]
Abstract
Maxillae and/or mandibles from 76 walruses (Odobenus rosmarus) were examined macroscopically according to predefined criteria. The museum specimens were acquired between 1932 and 2014. Forty-five specimens (59.2%) were from male animals, 29 (38.2%) from female animals and two (2.6%) from animals of unknown sex, with 58 adults (76.3%) and 18 young adults (23.7%) included in this study. The number of teeth available for examination was 830 (33.6%); 18.5% of teeth were absent artefactually, 3.3% were deemed to be absent due to acquired tooth loss and 44.5% were absent congenitally. The theoretical complete dental formula was confirmed to be I 3/3, C 1/1, P 4/3, M 2/2, while the most probable dental formula is I 1/0, C 1/1, P 3/3, M 0/0; none of the specimens in this study possessed a full complement of theoretically possible teeth. The majority of teeth were normal in morphology; only five teeth (0.6% of available teeth) were malformed. Only one tooth had an aberrant number of roots and only one supernumerary tooth was encountered. No persistent deciduous teeth were found in any of the young adult or adult specimens, nor were any specimens affected by enamel hypoplasia. The majority of teeth (85.5%) displayed attrition/abrasion. Of the adult and young adult specimens, 90.8% showed some degree of attrition/abrasion on at least one tooth. Tooth fractures were noted in eight walruses, affecting 10.5% of specimens and 1.3% of the total number of teeth, nearly three-quarters of which were maxillary canine teeth (tusks). Three specimens (3.9%), all adult males, displayed overt periapical disease. The majority (99.2%) of dental alveoli did not have bony changes indicative of periodontitis, with only five specimens (6.6%) affected by periodontitis. Lesions consistent with temporomandibular joint osteoarthritis (TMJ-OA) were found in 46 specimens (60.5%) and TMJ-OA was significantly more common in adults than young adults and males than females. Although the clinical significance of dental and TMJ pathology in the walrus remains unknown, the occurrence and severity of these lesions may play an important role in the morbidity and mortality of this species.
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Affiliation(s)
- J N Winer
- William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - B Arzi
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - D M Leale
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - P H Kass
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, USA
| | - F J M Verstraete
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
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16
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Atwood TC, Marcot BG, Douglas DC, Amstrup SC, Rode KD, Durner GM, Bromaghin JF. Forecasting the relative influence of environmental and anthropogenic stressors on polar bears. Ecosphere 2016. [DOI: 10.1002/ecs2.1370] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Todd C. Atwood
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - Bruce G. Marcot
- Pacific Northwest Research StationU.S.D.A. Forest Service Portland Oregon 97208 USA
| | - David C. Douglas
- Alaska Science CenterU.S. Geological Survey Juneau Alaska 99801 USA
| | | | - Karyn D. Rode
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
| | - George M. Durner
- Alaska Science CenterU.S. Geological Survey Anchorage Alaska 99508 USA
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17
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Noren SR, Udevitz MS, Jay CV. Sex-Specific Energetics of Pacific Walruses (Odobenus rosmarus divergens) during the Nursing Interval. Physiol Biochem Zool 2016; 89:93-109. [PMID: 27082720 DOI: 10.1086/685454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Habitat use and activity patterns of Pacific walruses (Odobenus rosmarus divergens) have changed with climate-induced reductions in sea ice. Increases in the time active in water could result in negative energy balance, precluding females from sustaining lactation, which could impact population demographics. Little is known about lactation costs in walruses. We examined the energetics of 0-2-yr-old walrus calves by using Bayesian hierarchical models based on longitudinal husbandry records of growth (n = 6 females and 7 males) and caloric intake (n = 5 females and 6 males) as a proxy for maternal lactation costs. Males and females had similar growth patterns; mean mass increased from 68 kg at birth to 301 kg by 2 yr. Females had a 2,000 kcal kg(-1) higher mass storage (growth) cost than males; females typically synthesize and deposit greater amounts of adipose, which is more energy dense than lean tissue. In contrast, males had higher metabolic (basal and activity) costs, ranging from 600 to 1,800 kcal d(-1) greater than similarly sized females; males are typically leaner, and muscle is more metabolically active than adipose. Yet total daily energy requirements (storage plus metabolic components) were similar across sexes, summing to approximately 190,000 kcal over the first month postpartum. Based on these estimates and assuming that 8,103 kcal is recovered from 1 kg of mass loss in adult female walruses, suckling calves could deplete 23 kg of their mother's body mass over the first month after parturition if none of the lactation costs is met through ingested prey.
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Ray GC, Hufford GL, Overland JE, Krupnik I, McCormick-Ray J, Frey K, Labunski E. Decadal Bering Sea seascape change: consequences for Pacific walruses and indigenous hunters. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:24-41. [PMID: 27039507 DOI: 10.1890/15-0430] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The most significant factors currently affecting the Pacific walrus (Odobenus rosmarus divergens) population are climate change and consequent changes in sea-ice morphology and dynamics. This paper integrates recent physical sea-ice change in the Bering Sea with biological and ecological conditions of walruses in their winter-spring reproductive habitat. Historically, walrus in winter-spring depended on a critical mass of sea-ice habitat to optimize social networking, reproductive fitness, feeding behavior, migration, and energetic efficiency. During 2003-2013, our cross-disciplinary, multiscale analysis from shipboard observations, satellite imagery, and ice-floe tracking, reinforced by information from indigenous subsistence hunters, documented change of sea-ice structure from a plastic continuum to a "mixing bowl" of ice floes moving more independently. This fragmentation of winter habitat preconditions the walrus population toward dispersal mortality and will also negatively affect the availability of resources for indigenous communities. We urge an expanded research and management agenda that integrates walrus natural history and habitat more completely with changing sea-ice morphology and dynamics at multiple scales, while also meeting the needs of local communities.
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Van Hemert C, Flint PL, Udevitz MS, Koch JC, Atwood TC, Oakley KL, Pearce JM. Forecasting Wildlife Response to Rapid Warming in the Alaskan Arctic. Bioscience 2015. [DOI: 10.1093/biosci/biv069] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Martin SL, Stohs SM, Moore JE. Bayesian inference and assessment for rare-event bycatch in marine fisheries: a drift gillnet fishery case study. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2015; 25:416-429. [PMID: 26263664 DOI: 10.1890/14-0059.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Fisheries bycatch is a global threat to marine megafauna. Environmental laws require bycatch assessment for protected species, but this is difficult when bycatch is rare. Low bycatch rates, combined with low observer coverage, may lead to biased, imprecise estimates when using standard ratio estimators. Bayesian model-based approaches incorporate uncertainty, produce less volatile estimates, and enable probabilistic evaluation of estimates relative to management thresholds. Here, we demonstrate a pragmatic decision-making process that uses Bayesian model-based inferences to estimate the probability of exceeding management thresholds for bycatch in fisheries with < 100% observer coverage. Using the California drift gillnet fishery as a case study, we (1) model rates of rare-event bycatch and mortality using Bayesian Markov chain Monte Carlo estimation methods and 20 years of observer data; (2) predict unobserved counts of bycatch and mortality; (3) infer expected annual mortality; (4) determine probabilities of mortality exceeding regulatory thresholds; and (5) classify the fishery as having low, medium, or high bycatch impact using those probabilities. We focused on leatherback sea turtles (Dermochelys coriacea) and humpback whales (Megaptera novaeangliae). Candidate models included Poisson or zero-inflated Poisson likelihood, fishing effort, and a bycatch rate that varied with area, time, or regulatory regime. Regulatory regime had the strongest effect on leatherback bycatch, with the highest levels occurring prior to a regulatory change. Area had the strongest effect on humpback bycatch. Cumulative bycatch estimates for the 20-year period were 104-242 leatherbacks (52-153 deaths) and 6-50 humpbacks (0-21 deaths). The probability of exceeding a regulatory threshold under the U.S. Marine Mammal Protection Act (Potential Biological Removal, PBR) of 0.113 humpback deaths was 0.58, warranting a "medium bycatch impact" classification of the fishery. No PBR thresholds exist for leatherbacks, but the probability of exceeding an anticipated level of two deaths per year, stated as part of a U.S. Endangered Species Act assessment process, was 0.0007. The approach demonstrated here would allow managers to objectively and probabilistically classify fisheries with respect to bycatch impacts on species that have population-relevant mortality reference points, and declare with a stipulated level of certainty that bycatch did or did not exceed estimated upper bounds.
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Noren SR, Jay CV, Burns JM, Fischbach AS. Rapid maturation of the muscle biochemistry that supports diving in pacific walruses (Odobenus rosmarus divergens). J Exp Biol 2015; 218:3319-29. [PMID: 26347559 DOI: 10.1242/jeb.125757] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 08/24/2015] [Indexed: 11/20/2022]
Abstract
Physiological constraints dictate animals' abilities to exploit habitats. For marine mammals, it is important to quantify physiological limits that influence diving and their ability to alter foraging behaviors. We characterized age-specific dive limits of walruses by measuring anaerobic (acid buffering capacity) and aerobic (myoglobin content) capacities of the muscles that power hind (longissimus dorsi) and fore (supraspinatus) flipper propulsion. Mean buffering capacities were similar across muscles and age classes (a fetus, 5 neonatal calves, a 3-month old, and 20 adults), ranging from 41.31 – 54.14 slykes and 42.00 – 46.93 slykes in the longissimus and supraspinatus, respectively. Mean myoglobin in the fetus and neonatal calves fell within a narrow range (longissimus: 0.92 – 1.68 g 100 g wet muscle mass−1; supraspinatus: 0.88 – 1.64 g wet muscle mass−1). By 3 months postpartum, myoglobin in the longissimus increased by 79%, but levels in the supraspinatus remained unaltered. From 3-months postpartum to adulthood, myoglobin increased by an additional 26% in the longissimus and increased by 126% in the supraspinatus; myoglobin remained greater in the longissimus compared to the supraspinatus. Walruses are unique among marine mammals because they are born with mature muscle acid buffering capacity and attain mature myoglobin content early in life. Despite rapid physiological development, small body size limits the diving capacity of immature walruses and extreme sexual dimorphism reduces the diving capacity of adult females compared to adult males. Thus, free-ranging immature walruses likely exhibit the shortest foraging dives while adult males are capable of the longest foraging dives.
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Affiliation(s)
- Shawn R. Noren
- Institute of Marine Science, University of California, Santa Cruz, Center for Ocean Health, 100 Shaffer Road, Santa Cruz, CA 95060, USA
| | - Chadwick V. Jay
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Jennifer M. Burns
- University of Alaska, Anchorage, Department of Biological Sciences, CPSB 202C, 3101 Science Circle, University of Alaska, Anchorage, AK 99508, USA
| | - Anthony S. Fischbach
- U.S. Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
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Noren SR, Udevitz MS, Jay CV. Energy demands for maintenance, growth, pregnancy, and lactation of female Pacific walruses (Odobenus rosmarus divergens). Physiol Biochem Zool 2014; 87:837-54. [PMID: 25461648 DOI: 10.1086/678237] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Decreases in sea ice have altered habitat use and activity patterns of female Pacific walruses Odobenus rosmarus divergens and could affect their energetic demands, reproductive success, and population status. However, a lack of physiological data from walruses has hampered efforts to develop the bioenergetics models required for fully understanding potential population-level impacts. We analyzed long-term longitudinal data sets of caloric consumption and body mass from nine female Pacific walruses housed at six aquaria using a hierarchical Bayesian approach to quantify relative energetic demands for maintenance, growth, pregnancy, and lactation. By examining body mass fluctuations in response to food consumption, the model explicitly uncoupled caloric demand from caloric intake. This is important for pinnipeds because they sequester and deplete large quantities of lipids throughout their lifetimes. Model outputs were scaled to account for activity levels typical of free-ranging Pacific walruses, averaging 83% of the time active in water and 17% of the time hauled-out resting. Estimated caloric requirements ranged from 26,900 kcal d(-1) for 2-yr-olds to 93,370 kcal d(-1) for simultaneously lactating and pregnant walruses. Daily consumption requirements were higher for pregnancy than lactation, reflecting energetic demands of increasing body size and lipid deposition during pregnancy. Although walruses forage during lactation, fat sequestered during pregnancy sustained 27% of caloric requirements during the first month of lactation, suggesting that walruses use a mixed strategy of capital and income breeding. Ultimately, this model will aid in our understanding of the energetic and population consequences of sea ice loss.
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Affiliation(s)
- Shawn R Noren
- Institute of Marine Science, University of California, Santa Cruz, California 95060; 2US Geological Survey, Alaska Science Center, Anchorage, Alaska 99508
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Pacific walrus (Odobenus rosmarus divergens) resource selection in the Northern Bering Sea. PLoS One 2014; 9:e93035. [PMID: 24717979 PMCID: PMC3981674 DOI: 10.1371/journal.pone.0093035] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 02/28/2014] [Indexed: 11/19/2022] Open
Abstract
The Pacific walrus is a large benthivore with an annual range extending across the continental shelves of the Bering and Chukchi Seas. We used a discrete choice model to estimate site selection by adult radio-tagged walruses relative to the availability of the caloric biomass of benthic infauna and sea ice concentration in a prominent walrus wintering area in the northern Bering Sea (St. Lawrence Island polynya) in 2006, 2008, and 2009. At least 60% of the total caloric biomass of dominant macroinfauna in the study area was composed of members of the bivalve families Nuculidae, Tellinidae, and Nuculanidae. Model estimates indicated walrus site selection was related most strongly to tellinid bivalve caloric biomass distribution and that walruses selected lower ice concentrations from the mostly high ice concentrations that were available to them (quartiles: 76%, 93%, and 99%). Areas with high average predicted walrus site selection generally coincided with areas of high organic carbon input identified in other studies. Projected decreases in sea ice in the St. Lawrence Island polynya and the potential for a concomitant decline of bivalves in the region could result in a northward shift in the wintering grounds of walruses in the northern Bering Sea.
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Lovvorn JR, Anderson EM, Rocha AR, Larned WW, Grebmeier JM, Cooper LW, Kolts JM, North CA. Variable wind, pack ice, and prey dispersion affect the long-term adequacy of protected areas for an Arctic sea duck. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2014; 24:396-412. [PMID: 24689150 DOI: 10.1890/13-0411.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
With changing climate, delineation of protected areas for sensitive species must account for long-term variability and geographic shifts of key habitat elements. Projecting the future adequacy of protected areas requires knowing major factors that drive such changes, and how readily the animals adjust to altered resources. In the Arctic, the viability of habitats for marine birds and mammals often depends on sea ice to dissipate storm waves and provide platforms for resting. However, some wind conditions (including weak winds during extreme cold) can consolidate pack ice into cover so dense that air-breathing divers are excluded from the better feeding areas. Spectacled Eiders (Somateria fischeri) winter among leads (openings) in pack ice in areas where densities of their bivalve prey are quite high. During winter 2009, however, prevailing winds created a large region of continuous ice with inadequate leads to allow access to areas of dense preferred prey. Stable isotope and fatty acid biomarkers indicated that, under these conditions, the eiders did not diversify their diet to include abundant non-bivalve taxa but did add a smaller, less preferred, bivalve species. Consistent with a computer model of eider energy balance, the body fat of adult eiders in 2009 was 33-35% lower than on the same date (19 March) in 2001 when ice conditions allowed access to higher bivalve densities. Ice cover data suggest that the eiders were mostly excluded from areas of high bivalve density from January to March in about 30% of 14 winters from 1998 to 2011. Thus, even without change in total extent of ice, shifts in prevailing winds can alter the areal density of ice to reduce access to important habitats. Because changes in wind-driven currents can also rearrange the dispersion of prey, the potential for altered wind patterns should be an important concern in projecting effects of climate change on the adequacy of marine protected areas for diving endotherms in the Arctic.
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Spatial variation and low diversity in the major histocompatibility complex in walrus (Odobenus rosmarus). Polar Biol 2014. [DOI: 10.1007/s00300-014-1450-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Monson DH, Udevitz MS, Jay CV. Estimating age ratios and size of pacific walrus herds on coastal haulouts using video imaging. PLoS One 2013; 8:e69806. [PMID: 23936106 PMCID: PMC3729469 DOI: 10.1371/journal.pone.0069806] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 06/12/2013] [Indexed: 11/18/2022] Open
Abstract
During Arctic summers, sea ice provides resting habitat for Pacific walruses as it drifts over foraging areas in the eastern Chukchi Sea. Climate-driven reductions in sea ice have recently created ice-free conditions in the Chukchi Sea by late summer causing walruses to rest at coastal haulouts along the Chukotka and Alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. Walrus age can be determined from the ratio of tusk length to snout dimensions. We evaluated use of images obtained from a gyro-stabilized video system mounted on a helicopter flying at high altitudes (to avoid disturbance) to classify the sex and age of walruses hauled out on Alaska beaches in 2010–2011. We were able to classify 95% of randomly selected individuals to either an 8- or 3-category age class, and we found measurement-based age classifications were more repeatable than visual classifications when using images presenting the correct head profile. Herd density at coastal haulouts averaged 0.88 walruses/m2 (std. err. = 0.02), herd size ranged from 8,300 to 19,400 (CV 0.03–0.06) and we documented ∼30,000 animals along ∼1 km of beach in 2011. Within the herds, dependent walruses (0–2 yr-olds) tended to be located closer to water, and this tendency became more pronounced as the herd spent more time on the beach. Therefore, unbiased estimation of herd age-ratios will require a sampling design that allows for spatial and temporal structuring. In addition, randomly sampling walruses available at the edge of the herd for other purposes (e.g., tagging, biopsying) will not sample walruses with an age structure representative of the herd. Sea ice losses are projected to continue, and population age structure data collected with aerial videography at coastal haulouts may provide demographic information vital to ongoing efforts to understand effects of climate change on this species.
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Affiliation(s)
- Daniel H Monson
- United States Geological Survey, Alaska Science Center, Anchorage, Alaska, USA.
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MacCracken JG, Garlich-Miller J, Snyder J, Meehan R. Bayesian belief network models for species assessments: An example with the Pacific walrus. WILDLIFE SOC B 2012. [DOI: 10.1002/wsb.229] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Sonsthagen SA, Jay CV, Fischbach AS, Sage GK, Talbot SL. Spatial genetic structure and asymmetrical gene flow within the Pacific walrus. J Mammal 2012. [DOI: 10.1644/11-mamm-a-344.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Abstract
Pacific walruses (Odobenus rosmarus divergens) occupying shelf waters of Pacific Arctic seas migrate during spring and summer from 3 breeding areas in the Bering Sea to form sexually segregated nonbreeding aggregations. We assessed genetic relationships among 2 putative breeding populations and 6 nonbreeding aggregations. Analyses of mitochondrial DNA (mtDNA) control region sequence data suggest that males are distinct among breeding populations (ΦST = 0.051), and between the eastern Chukchi and other nonbreeding aggregations (ΦST = 0.336–0.449). Nonbreeding female aggregations were genetically distinct across marker types (microsatellite FST = 0.019; mtDNA ΦST = 0.313), as was eastern Chukchi and all other nonbreeding aggregations (microsatellite FST = 0.019–0.035; mtDNA ΦST = 0.386–0.389). Gene flow estimates are asymmetrical from St. Lawrence Island into the southeastern Bering breeding population for both sexes. Partitioning of haplotype frequencies among breeding populations suggests that individuals exhibit some degree of philopatry, although weak. High levels of genetic differentiation among eastern Chukchi and all other nonbreeding aggregations, but considerably lower genetic differentiation between breeding populations, suggest that at least 1 genetically distinct breeding population remained unsampled. Limited genetic structure at microsatellite loci between assayed breeding areas can emerge from several processes, including male-mediated gene flow, or population admixture following a decrease in census size (i.e., due to commercial harvest during 1880–1950s) and subsequent recovery. Nevertheless, high levels of genetic diversity in the Pacific walrus, which withstood prolonged decreases in census numbers with little impact on neutral genetic diversity, may reflect resiliency in the face of past environmental challenges.
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Affiliation(s)
- Sarah A. Sonsthagen
- United States Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Chadwick V. Jay
- United States Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Anthony S. Fischbach
- United States Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - George K. Sage
- United States Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
| | - Sandra L. Talbot
- United States Geological Survey, Alaska Science Center, 4210 University Drive, Anchorage, AK 99508, USA
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Potential population-level effects of increased haulout-related mortality of Pacific walrus calves. Polar Biol 2012. [DOI: 10.1007/s00300-012-1259-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Maccracken JG. Pacific Walrus and climate change: observations and predictions. Ecol Evol 2012; 2:2072-90. [PMID: 22957206 PMCID: PMC3434008 DOI: 10.1002/ece3.317] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 11/11/2022] Open
Abstract
The extent and duration of sea-ice habitats used by Pacific walrus (Odobenus rosmarus divergens) are diminishing resulting in altered walrus behavior, mortality, and distribution. I document changes that have occurred over the past several decades and make predictions to the end of the 21st century. Climate models project that sea ice will monotonically decline resulting in more ice-free summers of longer duration. Several stressors that may impact walruses are directly influenced by sea ice. How these stressors materialize were modeled as most likely-case, worst-case, and best-case scenarios for the mid- and late-21st century, resulting in four comprehensive working hypotheses that can help identify and prioritize management and research projects, identify comprehensive mitigation actions, and guide monitoring programs to track future developments and adjust programs as needed. In the short term, the most plausible hypotheses predict a continuing northward shift in walrus distribution, increasing use of coastal haulouts in summer and fall, and a population reduction set by the carrying capacity of the near shore environment and subsistence hunting. Alternatively, under worst-case conditions, the population will decline to a level where the probability of extinction is high. In the long term, walrus may seasonally abandon the Bering and Chukchi Seas for sea-ice refugia to the northwest and northeast, ocean warming and pH decline alter walrus food resources, and subsistence hunting exacerbates a large population decline. However, conditions that reverse current trends in sea ice loss cannot be ruled out. Which hypothesis comes to fruition depends on how the stressors develop and the success of mitigation measures. Best-case scenarios indicate that successful mitigation of unsustainable harvests and terrestrial haulout-related mortalities can be effective. Management and research should focus on monitoring, elucidating effects, and mitigation, while ultimately, reductions in greenhouse gas emissions are needed to reduce sea-ice habitat losses.
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Affiliation(s)
- James G Maccracken
- U.S. Fish and Wildlife Service, Marine Mammals Management 1011 E. Tudor Rd, MS-341, Anchorage, Alaska, 99503
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Grebmeier JM. Shifting patterns of life in the Pacific Arctic and sub-Arctic seas. ANNUAL REVIEW OF MARINE SCIENCE 2012; 4:63-78. [PMID: 22457969 DOI: 10.1146/annurev-marine-120710-100926] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Recent changes in the timing of sea ice formation and retreat, along with increasing seawater temperatures, are driving shifts in marine species composition that may signal marine ecosystem reorganization in the Pacific Arctic sector. Interannual variability in seasonal sea ice retreat in the northern Bering Sea has been observed over the past decade; north of the Bering Strait, the Chukchi Sea ecosystem has had consistent earlier spring sea ice retreat and later fall sea ice formation. The latitudinal gradient in sea ice persistence, water column chlorophyll, and carbon export to the sediments has a direct impact on ecosystem structure in this Arctic/sub-Arctic complex. Large-scale decadal patterns in the benthic biological system are driven by sea ice extent, hydrographic forcing, and export production that influences benthic processes. Shifts in species composition and northward faunal range expansions indicate a changing system. The shifting patterns of life and change in key biological processes have the potential for a system-wide reorganization of the marine ecosystem.
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Affiliation(s)
- Jacqueline M Grebmeier
- Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomnons, Maryland 20688, USA.
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Vincent WF, Callaghan TV, Dahl-Jensen D, Johansson M, Kovacs KM, Michel C, Prowse T, Reist JD, Sharp M. Ecological Implications of Changes in the Arctic Cryosphere. AMBIO 2011; 40:87-99. [PMCID: PMC3357775 DOI: 10.1007/s13280-011-0218-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Snow, water, ice, and permafrost are showing evidence of substantial change in the Arctic, with large variations among different geographical areas. As a result of these changes, some habitats and their associated ecosystems are expanding, while others are undergoing rapid contraction. The warming of the Arctic cryosphere is limiting the range for cold-adapted biota, and less specialized taxa including invasive species from the south are likely to become increasingly common. Extreme climate events such as winter thawing are likely to become more frequent, and may accelerate shifts in community structure and processes. Many Arctic ecosystems are interdependent, and changes in the cryosphere are altering physical, biogeochemical, and biological linkages, as well as causing positive feedback effects on atmospheric warming. All of these climate-related effects are compounded by rapid socio-economic development in the North, creating additional challenges for northern communities and indigenous lifestyles that depend on Arctic ecosystem services.
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Affiliation(s)
- Warwick F. Vincent
- Département de Biologie & Centre d’Études Nordiques (CEN), Laval University, Québec City, QC G1V 0A6 Canada
| | | | - Dorthe Dahl-Jensen
- Niels Bohr Institutet, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Margareta Johansson
- Department of Earth and Ecosystem Sciences, Division of Physical Geography and Ecosystem Analyses, Lund University, Sölvegatan 12, 223 62 Lund, Sweden
| | | | - Christine Michel
- Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB R3T 2N6 Canada
| | - Terry Prowse
- Environment Canada, Department of Geography, University of Victoria, Victoria, BC V8P 5C2 Canada
| | - James D. Reist
- Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB R3T 2N6 Canada
| | - Martin Sharp
- Earth and Atmospheric Sciences, University of Alberta, Edmonton AB, T6G 2E3 Canada
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