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Franz M, Whyte L, Atwood TC, Laidre KL, Roy D, Watson SE, Góngora E, McKinney MA. Distinct gut microbiomes in two polar bear subpopulations inhabiting different sea ice ecoregions. Sci Rep 2022; 12:522. [PMID: 35017585 PMCID: PMC8752607 DOI: 10.1038/s41598-021-04340-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 12/13/2021] [Indexed: 11/09/2022] Open
Abstract
Gut microbiomes were analyzed by 16S rRNA gene metabarcoding for polar bears (Ursus maritimus) from the southern Beaufort Sea (SB), where sea ice loss has led to increased use of land-based food resources by bears, and from East Greenland (EG), where persistent sea ice has allowed hunting of ice-associated prey nearly year-round. SB polar bears showed a higher number of total (940 vs. 742) and unique (387 vs. 189) amplicon sequence variants and higher inter-individual variation compared to EG polar bears. Gut microbiome composition differed significantly between the two subpopulations and among sex/age classes, likely driven by diet variation and ontogenetic shifts in the gut microbiome. Dietary tracer analysis using fatty acid signatures for SB polar bears showed that diet explained more intrapopulation variation in gut microbiome composition and diversity than other tested variables, i.e., sex/age class, body condition, and capture year. Substantial differences in the SB gut microbiome relative to EG polar bears, and associations between SB gut microbiome and diet, suggest that the shifting foraging habits of SB polar bears tied to sea ice loss may be altering their gut microbiome, with potential consequences for nutrition and physiology.
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Affiliation(s)
- Megan Franz
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Lyle Whyte
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Todd C Atwood
- United States Geological Survey (USGS), Alaska Science Center, University Drive, Anchorage, AK, 99508, USA
| | - Kristin L Laidre
- Polar Science Center, Applied Physics Laboratory, University of Washington, Seattle, WA, USA
- Greenland Institute of Natural Resources, P.O. Box 570, Nuuk, Greenland
| | - Denis Roy
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Sophie E Watson
- School of Biosciences, Cardiff University, The Sir Martin Evans Building, Museum Avenue, Cardiff, UK
| | - Esteban Góngora
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Melissa A McKinney
- Department of Natural Resource Sciences, McGill University, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada.
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Diet composition and body condition of polar bears (Ursus maritimus) in relation to sea ice habitat in the Canadian High Arctic. Polar Biol 2021. [DOI: 10.1007/s00300-021-02891-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Florko KRN, Thiemann GW, Bromaghin JF. Drivers and consequences of apex predator diet composition in the Canadian Beaufort Sea. Oecologia 2020; 194:51-63. [PMID: 32897468 DOI: 10.1007/s00442-020-04747-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 08/28/2020] [Indexed: 10/23/2022]
Abstract
Polar bears (Ursus maritimus) rely on annual sea ice as their primary habitat for hunting marine mammal prey. Given their long lifespan, wide geographic distribution, and position at the top of the Arctic marine food web, the diet composition of polar bears can provide insights into temporal and spatial ecosystem dynamics related to climate-mediated sea ice loss. Polar bears with the greatest ecological constraints on diet composition may be most vulnerable to climate-related changes in ice conditions and prey availability. We used quantitative fatty acid signature analysis (QFASA) to estimate the diets of polar bears (n = 419) in two western Canadian Arctic subpopulations (Northern Beaufort Sea and Southern Beaufort Sea) from 1999 to 2015. Polar bear diets were dominated by ringed seal (Pusa hispida), with interannual, seasonal, age- and sex-specific variation. Foraging area and sea ice conditions also affected polar bear diet composition. Most variation in bear diet was explained by longitude, reflecting spatial variation in prey availability. Sea ice conditions (extent, thickness, and seasonal duration) declined throughout the study period, and date of sea ice break-up in the preceding spring was positively correlated with female body condition and consumption of beluga whale (Delphinapterus leucas), suggesting that bears foraged on beluga whales during entrapment events. Female body condition was positively correlated with ringed seal consumption, and negatively correlated with bearded seal consumption. This study provides insights into the complex relationships between declining sea ice habitat and the diet composition and foraging success of a wide-ranging apex predator.
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Affiliation(s)
- Katie R N Florko
- Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Gregory W Thiemann
- Faculty of Environmental Studies, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada
| | - Jeffrey F Bromaghin
- Alaska Science Center, U.S. Geological Survey, 4210 University Drive, Anchorage, AK, 99508, USA
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Vranković L, Delaš I, Reljić S, Huber Đ, Maltar-Strmečki N, Klobučar K, Krivić G, Stojević Z, Aladrović J. The Lipid Composition of Subcutaneous Adipose Tissue of Brown Bears (Ursus arctos) in Croatia. Physiol Biochem Zool 2017; 90:399-406. [PMID: 28384418 DOI: 10.1086/690913] [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
The composition of adipose tissue in brown bears (Ursus arctos) is highly variable and depends on an individual's feeding habits. Fatty acid composition of subcutaneous adipose tissue (SAT) may provide insight into brown bear feeding habits, for which data are scarce. The aim of this study was to determine the lipid composition of SAT and variations in the composition of fatty substances with regard to gender and to assess SAT relative to season and body mass (BM) of brown bears in Croatia. Seventy-six tissue samples of brown bear SAT were analyzed in this study. We found that gender, season, and BM significantly affected the lipid composition of SAT. Both females and males had higher percentages of saturated fatty acids and monounsaturated fatty acids (MUFAs) in SAT in spring than in autumn, while the percentage of polyunsaturated fatty acids (PUFAs) was higher in autumn. The prevalence of MUFAs in SAT and the greater presence of PUFAs in autumn, together with the presence of odd-chain saturated fatty acids, indicate the importance of these fatty acids in brown bear physiology. We suggest that the lipid content of adipose tissue may provide valuable information on changes in brown bear condition in response to feeding habits and the effects of supplemental feeding.
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Bromaghin JF, Budge SM, Thiemann GW, Rode KD. Assessing the robustness of quantitative fatty acid signature analysis to assumption violations. Methods Ecol Evol 2015. [DOI: 10.1111/2041-210x.12456] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Jeffrey F. Bromaghin
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage Alaska 99508 USA
| | - Suzanne M. Budge
- Process Engineering and Applied Science Dalhousie University Halifax NS B3H 4R2 Canada
| | - Gregory W. Thiemann
- Faculty of Environmental Studies York University 4700 Keele St. Toronto ON M3J 1P3 Canada
| | - Karyn D. Rode
- U.S. Geological Survey Alaska Science Center 4210 University Drive Anchorage Alaska 99508 USA
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Galicia MP, Thiemann GW, Dyck MG, Ferguson SH. Characterization of polar bear (Ursus maritimus) diets in the Canadian High Arctic. Polar Biol 2015. [DOI: 10.1007/s00300-015-1757-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bromaghin JF, Rode KD, Budge SM, Thiemann GW. Distance measures and optimization spaces in quantitative fatty acid signature analysis. Ecol Evol 2015; 5:1249-62. [PMID: 25859330 PMCID: PMC4377268 DOI: 10.1002/ece3.1429] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 01/21/2015] [Accepted: 01/27/2015] [Indexed: 11/24/2022] Open
Abstract
Quantitative fatty acid signature analysis has become an important method of diet estimation in ecology, especially marine ecology. Controlled feeding trials to validate the method and estimate the calibration coefficients necessary to account for differential metabolism of individual fatty acids have been conducted with several species from diverse taxa. However, research into potential refinements of the estimation method has been limited. We compared the performance of the original method of estimating diet composition with that of five variants based on different combinations of distance measures and calibration-coefficient transformations between prey and predator fatty acid signature spaces. Fatty acid signatures of pseudopredators were constructed using known diet mixtures of two prey data sets previously used to estimate the diets of polar bears Ursus maritimus and gray seals Halichoerus grypus, and their diets were then estimated using all six variants. In addition, previously published diets of Chukchi Sea polar bears were re-estimated using all six methods. Our findings reveal that the selection of an estimation method can meaningfully influence estimates of diet composition. Among the pseudopredator results, which allowed evaluation of bias and precision, differences in estimator performance were rarely large, and no one estimator was universally preferred, although estimators based on the Aitchison distance measure tended to have modestly superior properties compared to estimators based on the Kullback–Leibler distance measure. However, greater differences were observed among estimated polar bear diets, most likely due to differential estimator sensitivity to assumption violations. Our results, particularly the polar bear example, suggest that additional research into estimator performance and model diagnostics is warranted.
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Affiliation(s)
- Jeffrey F Bromaghin
- U.S. Geological Survey, Alaska Science Center 4210 University Drive, Anchorage, Alaska, 99508
| | - Karyn D Rode
- U.S. Geological Survey, Alaska Science Center 4210 University Drive, Anchorage, Alaska, 99508
| | - Suzanne M Budge
- Process Engineering and Applied Science, Dalhousie University Halifax, Nova Scotia, B3H 4R2, Canada
| | - Gregory W Thiemann
- Faculty of Environmental Studies, York University 4700 Keele St., Toronto, Ontario, M3J 1P3, Canada
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McKinney MA, Iverson SJ, Fisk AT, Sonne C, Rigét FF, Letcher RJ, Arts MT, Born EW, Rosing-Asvid A, Dietz R. Global change effects on the long-term feeding ecology and contaminant exposures of East Greenland polar bears. GLOBAL CHANGE BIOLOGY 2013; 19:2360-72. [PMID: 23640921 DOI: 10.1111/gcb.12241] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 03/31/2013] [Indexed: 05/04/2023]
Abstract
Rapid climate changes are occurring in the Arctic, with substantial repercussions for arctic ecosystems. It is challenging to assess ecosystem changes in remote polar environments, but one successful approach has entailed monitoring the diets of upper trophic level consumers. Quantitative fatty acid signature analysis (QFASA) and fatty acid carbon isotope (δ(13) C-FA) patterns were used to assess diets of East Greenland (EG) polar bears (Ursus maritimus) (n = 310) over the past three decades. QFASA-generated diet estimates indicated that, on average, EG bears mainly consumed arctic ringed seals (47.5 ± 2.1%), migratory subarctic harp (30.6 ± 1.5%) and hooded (16.7 ± 1.3%) seals and rarely, if ever, consumed bearded seals, narwhals or walruses. Ringed seal consumption declined by 14%/decade over 28 years (90.1 ± 2.5% in 1984 to 33.9 ± 11.1% in 2011). Hooded seal consumption increased by 9.5%/decade (0.0 ± 0.0% in 1984 to 25.9 ± 9.1% in 2011). This increase may include harp seal, since hooded and harp seal FA signatures were not as well differentiated relative to other prey species. Declining δ(13) C-FA ratios supported shifts from more nearshore/benthic/ice-associated prey to more offshore/pelagic/open-water-associated prey, consistent with diet estimates. Increased hooded seal and decreased ringed seal consumption occurred during years when the North Atlantic Oscillation (NAO) was lower. Thus, periods with warmer temperatures and less sea ice were associated with more subarctic and less arctic seal species consumption. These changes in the relative abundance, accessibility, or distribution of arctic and subarctic marine mammals may have health consequences for EG polar bears. For example, the diet change resulted in consistently slower temporal declines in adipose levels of legacy persistent organic pollutants, as the subarctic seals have higher contaminant burdens than arctic seals. Overall, considerable changes are occurring in the EG marine ecosystem, with consequences for contaminant dynamics.
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Vongraven D, Aars J, Amstrup S, Atkinson SN, Belikov S, Born EW, DeBruyn TD, Derocher AE, Durner G, Gill M, Lunn N, Obbard ME, Omelak J, Ovsyanikov N, Peacock E, Richardson E, Sahanatien V, Stirling I, Wiig Ø. A circumpolar monitoring framework for polar bears. URSUS 2012. [DOI: 10.2192/ursus-d-11-00026.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Knott KK, Boyd D, Ylitalo GM, O’Hara TM. Concentrations of mercury and polychlorinated biphenyls in blood of Southern Beaufort Sea polar bears (Ursus maritimus) during spring: variations with lipids and stable isotope (δ15N, δ13C) values. CAN J ZOOL 2011. [DOI: 10.1139/z11-071] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polar bears ( Ursus maritimus Phipps, 1774) are exposed to heavy metal and lipophilic contaminants that are known to bioaccumulate and biomagnify. Few studies concurrently report both chemical classes in the same individuals and are thus unable to assess drivers of observed tissue concentrations, and the potential adverse biological responses to combined exposures. We examined blood concentrations of mercury (Hg) and the sum of seven polychlorinated biphenyls (Σ7PCB) from free-ranging Southern Beaufort Sea polar bears to assess which factors contributed to variations among cohorts (adult males, adult females, young) during spring. Concentrations of Hg ranged from 10.3 to 228.0 ng/g wet mass, but mean concentrations were similar between males and females independent of age. Concentrations of Σ7PCB (range 2.0–132.8 ng/g wet mass) were greater among females and young than among males. Toxicant concentrations were related to packed cell δ15N, an estimate of trophic position, after the inclusion of packed cell δ13C. Concentrations of Σ7PCB were also positively correlated with concentrations of neutral lipids (triglycerides and free fatty acids) and inversely correlated to body condition indices. Elevated concentrations of toxicants and lower body condition indices in females and young compared with males may be a sentinel to a changing arctic environment. Further assessment of the potential adverse health impacts of contaminants and nutritional stress in these cohorts is warranted.
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Affiliation(s)
- Katrina K. Knott
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Daryle Boyd
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Environmental Conservation Division, Northwest Fisheries Science Center, Seattle, WA 98115, USA
| | - Gina M. Ylitalo
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Environmental Conservation Division, Northwest Fisheries Science Center, Seattle, WA 98115, USA
| | - Todd M. O’Hara
- Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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Peacock E, Derocher A, Thiemann G, Stirling I. Conservation and management of Canada’s polar bears (Ursus maritimus) in a changing Arctic1This review is part of the virtual symposium “Flagship Species – Flagship Problems” that deals with ecology, biodiversity and management issues, and climate impacts on species at risk and of Canadian importance, including the polar bear (Ursus maritimus), Atlantic cod (Gadus morhua), Piping Plover (Charadrius melodus), and caribou (Rangifer tarandus). CAN J ZOOL 2011. [DOI: 10.1139/z11-021] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Canada has an important responsibility for the research, conservation, and management of polar bears ( Ursus maritimus Phipps, 1774) because the majority of polar bears in the world occur within the nation’s borders. Two fundamental and recent changes for polar bears and their conservation have arisen: (1) the ongoing and projected further decline of sea-ice habitat as a result of climate change and (2) the implementation of aboriginal land claims and treaties in Canada’s North. Science has documented empirical links between productivity of polar bear population and sea-ice change. Predictive modeling based on these data has forecast significant declines in polar bear abundance and distribution of polar bears. With the signing of northern land claims and treaties, polar bear management in Canada has integrated local aboriginal participation, values, and knowledge. The interaction of scientific and local perspectives on polar bears as they relate to harvest, climate change, and declining habitat has recently caused controversy. Some conservation, management, and research decisions have been contentious because of gaps in scientific knowledge and the polarization and politicization of the roles of the various stakeholders. With these ecological and governance transitions, there is a need to re-focus and re-direct polar bear conservation in Canada.
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Affiliation(s)
- E. Peacock
- Department of Environment, Government of Nunavut, Igloolik, NU X0A 0L0 Canada
| | - A.E. Derocher
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada
| | - G.W. Thiemann
- Faculty of Environmental Studies, York University, Toronto, ON M3J 1P3 Canada
| | - I. Stirling
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada
- Wildlife Research Division, Environment Canada, 5320 122 Street, Edmonton, AB T6G 3S5, Canada
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Thiemann GW, Iverson SJ, Stirling I, Obbard ME. Individual patterns of prey selection and dietary specialization in an Arctic marine carnivore. OIKOS 2011. [DOI: 10.1111/j.1600-0706.2011.19277.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cherry SG, Derocher AE, Hobson KA, Stirling I, Thiemann GW. Quantifying dietary pathways of proteins and lipids to tissues of a marine predator. J Appl Ecol 2010. [DOI: 10.1111/j.1365-2664.2010.01908.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ravet JL, Brett MT, Arhonditsis GB. The effects of seston lipids on zooplankton fatty acid composition in Lake Washington, Washington, USA. Ecology 2010; 91:180-90. [DOI: 10.1890/08-2037.1] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Marshall HD, Hart KA, Yaskowiak ES, Stenson GB, McKinnon D, Perry EA. Molecular identification of prey in the stomach contents of Harp Seals (Pagophilus groenlandicus) using species-specific oligonucleotides. Mol Ecol Resour 2009; 10:181-9. [PMID: 21565007 DOI: 10.1111/j.1755-0998.2009.02713.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
All methods of diet analysis in marine mammals, including hard part analysis (HPA), have biases affecting the accuracy of prey-species identification and frequency in the estimated diet due to differential consumption, digestion and retention. Using PCR amplification of specific prey DNA with species-specific primers, we developed a DNA-based method that complements HPA and provides an alternative means to detect prey from stomach contents of Harp Seals (Pagophilus groenlandicus). The target size that could be reliably amplified was determined using a digestion time-series of Atlantic Cod (Gadus morhua) tissue in simulated seal stomachs. Various target lengths were trialed using general teleost primers; amplicons of approximately 800 bp or less were consistently obtained. Prey species-specific PCR primers for Atlantic Cod, Arctic Cod (Boreogadus saida) and Capelin (Mallotus villosus) were designed and tested with DNA from the stomach contents of 31 Harp Seals. Amplicons were obtained for all three species-specific primer sets. Amplification results compared with HPA revealed: (i) Atlantic Cod hard parts were found in five stomachs where no Atlantic Cod DNA amplified, suggesting that Atlantic Cod may be over-represented in the estimated diet, (ii) amplification of Arctic Cod DNA occurred for 17 stomachs, including all 12 stomachs with, and five stomachs without, Arctic Cod hard parts, and (iii) Capelin DNA amplified for four of five stomachs with Capelin hard parts and for one stomach without Capelin hard parts. We conclude that PCR amplification of specific prey DNA provides a viable means to complement Harp Seal diet analysis by HPA, but suggest that valuable information for quantitative diet analysis rests in a quantitative PCR approach.
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Affiliation(s)
- H D Marshall
- Department of Biology, Memorial University of Newfoundland, St. John's, NF, Canada A1B 3X9 Genomics and Proteomics Facility, CREAIT Network, Memorial University of Newfoundland, St. John's, NF, Canada A1B 3X9 Science Branch, Department of Fisheries and Oceans, Northwest Atlantic Fisheries Centre, PO Box 5667, St. John's, NF, Canada A1C 5X1 Department of Psychology, Memorial University of Newfoundland, St. John's, NF, Canada A1B 3X9
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Thiemann GW, Iverson SJ, Stirling I. POLAR BEAR DIETS AND ARCTIC MARINE FOOD WEBS: INSIGHTS FROM FATTY ACID ANALYSIS. ECOL MONOGR 2008. [DOI: 10.1890/07-1050.1] [Citation(s) in RCA: 253] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Thiemann GW. Using fatty acid signatures to study bear foraging: Technical considerations and future applications. URSUS 2008. [DOI: 10.2192/08per001r.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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