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Anderson MA, Fisk AT, Laing R, Noël M, Angnatok J, Kirk J, Evans M, Pijogge L, Brown TM. Changing environmental conditions have altered the feeding ecology of two keystone Arctic marine predators. Sci Rep 2023; 13:14056. [PMID: 37640733 PMCID: PMC10462653 DOI: 10.1038/s41598-023-39091-9] [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] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 07/20/2023] [Indexed: 08/31/2023] Open
Abstract
Environmental change in the Arctic has impacted the composition and structure of marine food webs. Tracking feeding ecology changes of culturally-valued Arctic char (Salvelinus alpinus) and ringed seals (Pusa hispida) can provide an indication of the ecological significance of climate change in a vulnerable region. We characterized how changes in sea ice conditions, sea surface temperature (SST), and primary productivity affected the feeding ecology of these two keystone species over a 13- and 18-year period, respectively, in northern Labrador, Canada. Arctic char fed consistently on pelagic resources (δ13C) but shifted over time to feeding at a higher trophic level (δ15N) and on more marine/offshore resources (δ34S), which correlated with decreases in chlorophyll a concentration. A reduction in Arctic char condition factor and lipid content was associated with higher trophic position. Ringed seals also shifted to feeding at a higher trophic level, but on more pelagic resources, which was associated with lower SST and higher chlorophyll a concentrations. Years with abnormally high SSTs and reduced sea ice concentrations resulted in large isotopic niche sizes for both species, suggesting abrupt change can result in more variable feeding. Changes in abundance and distribution of species long valued by the Inuit of Labrador could diminish food security.
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Affiliation(s)
| | - Aaron T Fisk
- School of the Environment, University of Windsor, Windsor, ON, Canada
| | - Rodd Laing
- Nunatsiavut Government, Nain, NL, Canada
| | | | | | - Jane Kirk
- Environment and Climate Change Canada, Burlington, ON, Canada
| | - Marlene Evans
- Environment and Climate Change Canada, Saskatoon, SK, Canada
| | | | - Tanya M Brown
- School of the Environment, University of Windsor, Windsor, ON, Canada.
- Fisheries and Oceans Canada, West Vancouver, BC, Canada.
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Crain DD, Karpovich SA, Quakenbush L, Polasek L. Using claws to compare reproduction, stress and diet of female bearded and ringed seals in the Bering and Chukchi seas, Alaska, between 1953-1968 and 1998-2014. CONSERVATION PHYSIOLOGY 2021; 9:coaa115. [PMID: 33442472 PMCID: PMC7786451 DOI: 10.1093/conphys/coaa115] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/27/2020] [Accepted: 11/20/2020] [Indexed: 05/08/2023]
Abstract
Rapid climate warming is decreasing sea ice thickness, extent and duration. Marine mammals such as bearded (Erignathus barbatus) and ringed (Pusa hispida) seals, which use sea ice for pupping, molting and resting, may be negatively affected. Claws from bearded and ringed seals store up to 14 and 12 years of sequential analyte data, respectively. These data can be used to compare reproduction, stress and diet across decades. In this study, we compare progesterone, cortisol and carbon and nitrogen stable isotopes in female bearded and ringed seals during 1953-1968 (pre-1968, a period prior to sea ice decline) to 1998-2014 (post-1998, a period during sea ice decline). When comparing these periods, bearded seals had statistically higher cortisol concentrations post-1998, and for both species δ13C was more negative post-1998, while progesterone and δ15N did not change. There was a positive relationship between progesterone and cortisol Z-scores for both species, except for ringed seals post-1998. There was a negative relationship between cortisol Z-scores and δ13C for bearded seals evident in post-1998 indicating that higher cortisol Z-scores are associated with more negative δ13C in bearded seals in recent years. This negative relationship between cortisol and δ13C in bearded seals suggests a shift to higher prey diversity, possibly due to changes in sea ice in the Pacific Arctic evident post 1998. Progesterone Z-scores corresponded to expected differences among non-pregnant, unimplanted, implanted and post-partum individuals. Using these data, pregnancy history was determined for reproductive years for each individual female sampled, which could allow for yearly pregnancy rates to be calculated given a large enough representative sample of the population. These results combine decades of observational studies with hormones and stable isotopes to infer changes in reproduction, stress and diet, as well as the connection between these life history parameters.
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Affiliation(s)
| | - Shawna A Karpovich
- Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701, USA
| | - Lori Quakenbush
- Alaska Department of Fish and Game, 1300 College Road, Fairbanks, AK 99701, USA
| | - Lori Polasek
- Alaska Department of Fish and Game, 1255 W 8 St, Juneau, AK 99802, USA
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3
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Thometz NM, Hermann-Sorensen H, Russell B, Rosen DAS, Reichmuth C. Molting strategies of Arctic seals drive annual patterns in metabolism. CONSERVATION PHYSIOLOGY 2021; 9:coaa112. [PMID: 33659059 PMCID: PMC7905162 DOI: 10.1093/conphys/coaa112] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 09/30/2020] [Accepted: 11/09/2020] [Indexed: 06/12/2023]
Abstract
Arctic seals, including spotted (Phoca largha), ringed (Pusa hispida) and bearded (Erignathus barbatus) seals, are directly affected by sea ice loss. These species use sea ice as a haul-out substrate for various critical functions, including their annual molt. Continued environmental warming will inevitably alter the routine behavior and overall energy budgets of Arctic seals, but it is difficult to quantify these impacts as their metabolic requirements are not well known-due in part to the difficulty of studying wild individuals. Thus, data pertaining to species-specific energy demands are urgently needed to better understand the physiological consequences of rapid environmental change. We used open-flow respirometry over a four-year period to track fine-scale, longitudinal changes in the resting metabolic rate (RMR) of four spotted seals, three ringed seals and one bearded seal trained to participate in research. Simultaneously, we collected complementary physiological and environmental data. Species-specific metabolic demands followed expected patterns based on body size, with the largest species, the bearded seal, exhibiting the highest absolute RMR (0.48 ± 0.04 L O2 min-1) and the lowest mass-specific RMR (4.10 ± 0.47 ml O2 min-1 kg-1), followed by spotted (absolute: 0.33 ± 0.07 L O2 min-1; mass-specific: 6.13 ± 0.73 ml O2 min-1 kg-1) and ringed (absolute: 0.20 ± 0.04 L O2 min-1; mass-specific: 7.01 ± 1.38 ml O2 min-1 kg-1) seals. Further, we observed clear and consistent annual patterns in RMR that related to the distinct molting strategies of each species. For species that molted over relatively short intervals-spotted (33 ± 4 days) and ringed (28 ± 6 days) seals-metabolic demands increased markedly in association with molt. In contrast, the bearded seal exhibited a prolonged molting strategy (119 ± 2 days), which appeared to limit the overall cost of molting as indicated by a relatively stable annual RMR. These findings highlight energetic trade-offs associated with different molting strategies and provide quantitative data that can be used to assess species-specific vulnerabilities to changing conditions.
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Affiliation(s)
- Nicole M Thometz
- Department of Biology, University of San Francisco, 2130 Fulton St, San Francisco, 94117 CA, USA
- Institute of Marine Sciences, University of California Santa Cruz, Long Marine Laboratory, 115 McAllister Way, Santa Cruz, 95060 CA, USA
| | - Holly Hermann-Sorensen
- Institute of Marine Sciences, University of California Santa Cruz, Long Marine Laboratory, 115 McAllister Way, Santa Cruz, 95060 CA, USA
| | - Brandon Russell
- Alaska SeaLife Center, 301 Railway Ave, Seward, 99664 AK, USA
| | - David A S Rosen
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, The University of British Columbia, 2202 Main Mall, Vancouver, BC V6T 1Z4, Canada
| | - Colleen Reichmuth
- Institute of Marine Sciences, University of California Santa Cruz, Long Marine Laboratory, 115 McAllister Way, Santa Cruz, 95060 CA, USA
- Alaska SeaLife Center, 301 Railway Ave, Seward, 99664 AK, USA
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4
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Boucher NP, Derocher AE, Richardson ES. Spatial and temporal variability in ringed seal ( Pusa hispida) stable isotopes in the Beaufort Sea. Ecol Evol 2020; 10:4178-4192. [PMID: 32489588 PMCID: PMC7246210 DOI: 10.1002/ece3.6186] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/02/2022] Open
Abstract
Arctic ecosystem dynamics are shifting in response to warming temperatures and sea ice loss. Such ecosystems may be monitored by examining the diet of upper trophic level species, which varies with prey availability. To assess interannual variation in the Beaufort Sea ecosystem, we examined spatial and temporal trends in ringed seal (Pusa hispida) δ13C and δ15N in claw growth layers grown from 1964 to 2011. Stable isotopes were correlated with climate indices, environmental conditions, seal population productivity, and geographic location. Sex and age did not influence stable isotopes. Enriched 13C was linked to cyclonic circulation regimes, seal productivity, and westward sampling locations. Higher δ15N was linked to lower sea surface temperatures, a higher percentage of pups in the subsistence harvest, and sample locations that were eastward and further from shore. From the 1960s to 2000s, ringed seal niche width expanded, suggesting a diversification of diet due to expansion of prey and/or seal space use. Overall, trends in ringed seal stable isotopes indicate changes within the Beaufort Sea ecosystem affected by water temperatures and circulation regimes. We suggest that continued monitoring of upper trophic level species will yield insights into changing ecosystem structure with climate change.
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Affiliation(s)
- Nicole P. Boucher
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
| | | | - Evan S. Richardson
- Wildlife Research Division, Science and Technology BranchEnvironment and Climate Change CanadaWinnipegMBCanada
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5
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Chételat J, Ackerman JT, Eagles-Smith CA, Hebert CE. Methylmercury exposure in wildlife: A review of the ecological and physiological processes affecting contaminant concentrations and their interpretation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 711:135117. [PMID: 31831233 DOI: 10.1016/j.scitotenv.2019.135117] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/15/2019] [Accepted: 10/21/2019] [Indexed: 05/12/2023]
Abstract
Exposure to methylmercury (MeHg) can result in detrimental health effects in wildlife. With advances in ecological indicators and analytical techniques for measurement of MeHg in a variety of tissues, numerous processes have been identified that can influence MeHg concentrations in wildlife. This review presents a synthesis of theoretical principals and applied information for measuring MeHg exposure and interpreting MeHg concentrations in wildlife. Mercury concentrations in wildlife are the net result of ecological processes influencing dietary exposure combined with physiological processes that regulate assimilation, transformation, and elimination. Therefore, consideration of both physiological and ecological processes should be integrated when formulating biomonitoring strategies. Ecological indicators, particularly stable isotopes of carbon, nitrogen, and sulfur, compound-specific stable isotopes, and fatty acids, can be effective tools to evaluate dietary MeHg exposure. Animal species differ in their physiological capacity for MeHg elimination, and animal tissues can be inert or physiologically active, act as sites of storage, transformation, or excretion of MeHg, and vary in the timing of MeHg exposure they represent. Biological influences such as age, sex, maternal transfer, and growth or fasting are also relevant for interpretation of tissue MeHg concentrations. Wildlife tissues that represent current or near-term bioaccumulation and in which MeHg is the predominant mercury species (such as blood and eggs) are most effective for biomonitoring ecosystems and understanding landscape drivers of MeHg exposure. Further research is suggested to critically evaluate the use of keratinized external tissues to measure MeHg bioaccumulation, particularly for less-well studied wildlife such as reptiles and terrestrial mammals. Suggested methods are provided to effectively use wildlife for quantifying patterns and drivers of MeHg bioaccumulation over time and space, as well as for assessing the potential risk and toxicological effects of MeHg on wildlife.
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Affiliation(s)
- John Chételat
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada.
| | - Joshua T Ackerman
- U.S. Geological Survey, Western Ecological Research Center, Dixon Field Station, 800 Business Park Drive, Suite D, Dixon, CA 95620, United States
| | - Collin A Eagles-Smith
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, Oregon, 97331, United States
| | - Craig E Hebert
- Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, ON K1A 0H3, Canada
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6
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Karpovich SA, Horstmann LA, Polasek LK. Validation of a novel method to create temporal records of hormone concentrations from the claws of ringed and bearded seals. CONSERVATION PHYSIOLOGY 2020; 8:coaa073. [PMID: 32864135 PMCID: PMC7446537 DOI: 10.1093/conphys/coaa073] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 05/29/2020] [Accepted: 08/03/2020] [Indexed: 05/12/2023]
Abstract
Ringed (Pusa hispida) and bearded seals (Erignathus barbatus) inhabit vast and often remote areas in the Arctic, making it difficult to obtain long-term physiological information concerning health and reproduction. These seals are experiencing climate-driven changes in their habitat that could result in physiological stress. Chronic physiological stress can lead to immunosuppression, decreased reproduction and decreased growth. Recently, keratin has become a popular matrix to measure steroid hormones, such as stress-related cortisol and reproduction-related progesterone. We developed and validated methods to extract cortisol and progesterone from the claws of adult female ringed (n = 20) and bearded (n = 3) seals using enzyme immunosorbent assays. As ringed and bearded seal claws grow, a pair of dark- and light-colored bands of keratin is deposited annually providing a guide for sampling. Two processing methods were evaluated, removal of claw material with a grinding bit or grinding followed by mechanical pulverization (102 paired samples from six claws, two each from three seals). Adding the mechanical pulverization step resulted in a 1.5-fold increase in hormone extraction. Progesterone from the proximal claw band was evaluated to biologically validate claw material as a measure of pregnancy in ringed seals (n = 14). Claws from pregnant seals had significantly higher claw progesterone concentrations than from non-pregnant seals. This suggests that the elevated progesterone associated with gestation was reflected in the claws, and that the most proximal claw band was indicative of pregnancy status at time of death. Thus, although the sample size was low and the collection dates unbalanced, this study demonstrates the potential to use claws to examine an extended time series (up to 12 yrs) of cortisol and progesterone concentrations in ringed and bearded seal claws.
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Affiliation(s)
- Shawna A Karpovich
- Alaska Department of Fish and Game, Marine Mammal Program, Fairbanks, AK 99701, USA
- Corresponding author: Alaska Department of Fish and Game, Marine Mammal Program, Fairbanks, AK 99701, USA. Tel: 907 459 7322.
| | - Larissa A Horstmann
- College of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, AK 99775, USA
| | - Lori K Polasek
- Alaska Department of Fish and Game, Marine Mammal Program, Juneau, AK 99811, USA
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7
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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]
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Ferguson SH, Yurkowski DJ, Young BG, Willing C, Zhu X, Muir DCG, Fisk AT, Thiemann GW. Do intraspecific life history patterns follow interspecific predictions? A test using latitudinal variation in ringed seals. POPUL ECOL 2019. [DOI: 10.1002/1438-390x.12008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Steven H. Ferguson
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
| | - David J. Yurkowski
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
| | - Brent G. Young
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
| | - Cornelia Willing
- Department of Biological Sciences University of Manitoba Winnipeg Manitoba Canada
- Centre for Earth Observation Science University of Manitoba Winnipeg Manitoba Canada
| | - Xinhua Zhu
- Department of Fisheries and Oceans Canada Winnipeg Manitoba Canada
- Great Lakes Institute for Environmental Research University of Windsor Windsor Ontario Canada
| | - Derek C. G. Muir
- Environment and Climate Change Canada Aquatic Contaminants Research Division Burlington Ontario Canada
| | - Aaron T. Fisk
- Great Lakes Institute for Environmental Research University of Windsor Windsor Ontario Canada
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9
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Wang SW, Springer AM, Budge SM, Horstmann L, Quakenbush LT, Wooller MJ. Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2016; 26:830-845. [PMID: 27411254 DOI: 10.1890/14-2421] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering-Chukchi continental shelf have occurred in this century, raising a pressing ecological question: Do such environmental changes alter marine production processes linking primary producers to upper trophic-level predators? We examined this question by comparing the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ¹³CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as "ice seals," sampled during an anomalously warm, low sea ice period in 2002-2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007-2010. δ¹³C(FA) values, used to estimate the contribution to seals of carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), indicated that during the cold period, sympagic production accounted for 62-80% of the FA in the blubber of bearded seals, 51-62% in spotted seals, and 21-60% in ringed seals. Moreover, the δ¹³CFA values of bearded seals indicated a greater incorporation of sympagic FAs during the cold period than the warm period. This result provides the first empirical evidence of an ecosystem-scale effect of a putative change in sympagic production in the Western Arctic. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. Despite interannual variability, the FA composition of ringed and bearded seals showed little evidence of differences in diet between the warm and cold periods. The findings that sympagic production contributes significantly to food webs supporting ice seals, and that the contribution apparently is less in warm years with low sea ice, raise an important concern: Will the projected warming and continuing loss of seasonal sea ice in the Arctic, and the associated decline of organic matter input from sympagic production, be compensated for by pelagic production to satisfy both pelagic and benthic carbon and energy needs?
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10
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Noël M, Jeffries S, Lambourn DM, Telmer K, Macdonald R, Ross PS. Mercury Accumulation in Harbour Seals from the Northeastern Pacific Ocean: The Role of Transplacental Transfer, Lactation, Age and Location. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2016; 70:56-66. [PMID: 26159879 DOI: 10.1007/s00244-015-0193-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 06/29/2015] [Indexed: 06/04/2023]
Abstract
Mercury (Hg) bioaccumulates in the aquatic food chain in the form of methylmercury, a compound well known for its neurotoxicity. We analyzed total mercury (THg) in hair collected from 209 harbour seals captured at 10 sites in British Columbia (Canada) and Washington State (USA) between 2003 and 2010. In addition, laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) allowed for a highly refined analysis of THg accumulation over time by examining nine whiskers taken from 4- to 6-week-old pups. We estimate that THg concentrations in pups increased sharply at a point corresponding to mid- to late gestation of their time in utero (4.7 ± 0.8 and 6.6 ± 1.3 µg/g dry weight (dw), respectively), and then again at the onset of nursing (8.1 ± 1.3 µg/g dw). These abrupt changes highlight the importance of both pre- and post-natal THg transfer from the mother to the growing fetus and the newborn pup. While THg levels varied among sites, hair analyses from seals collected at the same site demonstrated the influence of age in THg accumulation with pups (5.3 ± 0.3 µg/g) and juveniles (4.5 ± 0.5 µg/g) having lower levels than those in adults (8.3 ± 0.8 µg/g). Our results revealed that 33 % of the pups sampled (n = 167) had THg levels that surpassed a mammalian hair threshold for neurochemical alterations. This study suggests that Hg could represent a health concern to marine wildlife, especially as atmospheric emissions of this toxic element from human activities in the Pacific Rim and worldwide continue.
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Affiliation(s)
- Marie Noël
- School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, V8W 3P6, Canada
- Ocean Pollution Research Program, Coastal Ocean Research Institute, Vancouver Aquarium Marine Science Center, P.O. Box 3232, Vancouver, BC, V6B 3X8, Canada
| | - Steven Jeffries
- Washington Department of Fish and Wildlife, 7801 Philips Road, Lakewood, WA, 98498, USA
| | - Dyanna M Lambourn
- Washington Department of Fish and Wildlife, 7801 Philips Road, Lakewood, WA, 98498, USA
| | - Kevin Telmer
- School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, V8W 3P6, Canada
- Artisanal Gold Council, 101-732 Cormorant St., Victoria, BC, V8W 4A5, Canada
| | - Robie Macdonald
- Institute of Ocean Sciences, Fisheries and Oceans Canada, P.O. Box 6000, Sidney, BC, V8L 4B2, Canada
| | - Peter S Ross
- Ocean Pollution Research Program, Coastal Ocean Research Institute, Vancouver Aquarium Marine Science Center, P.O. Box 3232, Vancouver, BC, V6B 3X8, Canada.
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Bechshoft T, Derocher AE, Richardson E, Mislan P, Lunn NJ, Sonne C, Dietz R, Janz DM, St Louis VL. Mercury and cortisol in Western Hudson Bay polar bear hair. ECOTOXICOLOGY (LONDON, ENGLAND) 2015; 24:1315-1321. [PMID: 26044932 DOI: 10.1007/s10646-015-1506-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/30/2015] [Indexed: 06/04/2023]
Abstract
Non-invasive methods of assessing animal health and life history are becoming increasingly popular in wildlife research; hair samples from polar bears (Ursus maritimus), are being used to study an ever broader range of anthropogenic and endocrine compounds. A number of contaminants are known to disrupt endocrine function in polar bears. However, the relationship between mercury and cortisol remains unknown, although mercury is an endocrine disruptor in other species. Here, we examine the relationship between concentrations of cortisol and total mercury (THg) analyzed in guard hair from 378 polar bears (184 females, 194 males) sampled in Western Hudson Bay, 2004-2012. The difference in mean cortisol concentration between female (0.8 ± 0.6 pg/mg) and male (0.7 ± 0.5 pg/mg) polar bears bordered on significance (p = 0.054). However, mean mercury concentration was significantly greater (p = 0.009) in females (4.7 ± 1.4 μg/g) than males (4.3 ± 1.2 μg/g). Hair cortisol in males was significantly influenced by mercury, age, and fatness, as well as interactions between mercury and year, mercury and fatness, and year and fatness (all: p < 0.03) (multiple regression analysis, whole model: r(2) = 0.14, F(7,185) = 4.43, p = 0.0001). Fatness was the only significant variable in the multiple regression analysis for females (r(2) = 0.06, F(1,182) = 13.0, p = 0.0004). In conclusion, a significant, but complex, relationship was found between mercury and cortisol concentrations in hair from male, but not female, polar bears.
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Affiliation(s)
- T Bechshoft
- Department of Biological Sciences, University of Alberta, Edmonton, AB, T6G 2E9, Canada,
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12
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Carroll SS, Horstmann-Dehn L, Norcross BL. Diet history of ice seals using stable isotope ratios in claw growth bands. CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0137] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Climate change and sea-ice reduction may lead to modifications of food-web structure in the Arctic, and this may impact foraging of ice-associated predators. We examined the dietary history recorded in cornified claw sheaths of ringed seals (Pusa hispida (Schreber, 1775)) and bearded seals (Erignathus barbatus (Erxleben, 1777)) to describe potential seasonal and interannual changes in their foraging. Seasonal layers of cornified cells deposited in claws can document trophic history up to about 10 years; thereafter, the claws start to wear at the distal end. A total of 38 claws were collected during Alaska Native subsistence harvests in 2008–2010 and seasonal growth bands were examined for stable nitrogen and carbon isotope ratios to assess long-term diet patterns. During 2007 (record ice minimum), proportionally more ringed seals fed at a lower trophic level. Bearded seals may have been foraging more pelagically from 2008 to 2010. Interannual variations and high variability between the two ice seal species and among individual diets illustrate the opportunistic nature and flexibility of ice seals to changes in prey.
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Affiliation(s)
- Sara S. Carroll
- University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, Fairbanks, AK 99775, USA
| | - Larissa Horstmann-Dehn
- University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, Fairbanks, AK 99775, USA
| | - Brenda L. Norcross
- University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, Fairbanks, AK 99775, USA
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13
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Gorlova EN, Krylovich OA, Savinetsky AB, Khasanov BF. Ecology of the ringed seal (Pusa hispida) from the Bering Strait in the late Holocene. BIOL BULL+ 2012. [DOI: 10.1134/s1062359012050056] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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