Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis
Dissertation (Ph.D.) University of Alaska Fairbanks, 2014 The changing Arctic ecosystem may prompt Pacific walruses (Odobenus rosmarus divergens) to change their usual diet of lower trophic level prey (e.g., benthic invertebrates) by increasing the consumption of higher trophic level prey (HTLP). Pr...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/4566 2023-05-15T14:31:14+02:00 Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis Seymour, Jill-Marie Horstmann-Dehn, Lara Atkinson, Shannon Barboza, Perry Rosa, Cheryl Sheffield, Gay Wooller, Matthew 2014-05 http://hdl.handle.net/11122/4566 unknown http://hdl.handle.net/11122/4566 Program in Marine Science and Limnology Dissertation phd 2014 ftunivalaska 2023-02-23T21:36:15Z Dissertation (Ph.D.) University of Alaska Fairbanks, 2014 The changing Arctic ecosystem may prompt Pacific walruses (Odobenus rosmarus divergens) to change their usual diet of lower trophic level prey (e.g., benthic invertebrates) by increasing the consumption of higher trophic level prey (HTLP). Prey-switching may have consequences to walrus populations through increased energetic costs, increased stress response, declines in body condition, and exposure to diseases, including the zoonotic parasite Trichinella spp. Trichinella is possibly transmitted to walruses via predation or scavenging on seals. The goal of this study was to quantify reliance on HTLP using stable carbon and nitrogen isotope ratios, and assess potential correlations among consumption of HTLP and sea ice extent, sex, Trichinella infection, body lipid stores, and cortisol concentrations used as an index of the stress response. Walrus diet is comprised of ~1-22% HTLP and reliance on HTLP may be correlated with sea ice extent in a complex way. Trichinella was present in ringed seal (Pusa hispida, 1/57), Arctic fox (Vulpes lagopus, 3-7/32), and polar bear (Ursus maritimus, 1/1), but was not detected in walruses (0/137) regardless of %HTLP in the diet. Walrus blubber and attached skin contained 44.6 ±12.4% lipid wet weight, which was lower than that found for other Arctic marine mammals; however, the inclusion of skin likely decreased our %lipid values. While the absolute value of %lipid from blubber and attached skin was not a suitable substitute for %lipid from blubber only, we were still able to detect the influence of biological factors, with sex-linked variability in walrus lipid stores observed. Cortisol analysis from full-thickness blubber resulted in a wide range of concentrations (2.77 to 34.04 ng/g), but showed that this stress hormone can be extracted from blubber. While neither %lipid nor blubber cortisol was correlated with the proportion of HTLP in walrus diet, they may serve as minimally-invasive methods for health monitoring of ... Doctoral or Postdoctoral Thesis Arctic Fox Arctic marine mammals Arctic Odobenus rosmarus Pusa hispida ringed seal Sea ice Ursus maritimus Vulpes lagopus Alaska walrus* University of Alaska: ScholarWorks@UA Arctic Fairbanks Pacific |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
unknown |
description |
Dissertation (Ph.D.) University of Alaska Fairbanks, 2014 The changing Arctic ecosystem may prompt Pacific walruses (Odobenus rosmarus divergens) to change their usual diet of lower trophic level prey (e.g., benthic invertebrates) by increasing the consumption of higher trophic level prey (HTLP). Prey-switching may have consequences to walrus populations through increased energetic costs, increased stress response, declines in body condition, and exposure to diseases, including the zoonotic parasite Trichinella spp. Trichinella is possibly transmitted to walruses via predation or scavenging on seals. The goal of this study was to quantify reliance on HTLP using stable carbon and nitrogen isotope ratios, and assess potential correlations among consumption of HTLP and sea ice extent, sex, Trichinella infection, body lipid stores, and cortisol concentrations used as an index of the stress response. Walrus diet is comprised of ~1-22% HTLP and reliance on HTLP may be correlated with sea ice extent in a complex way. Trichinella was present in ringed seal (Pusa hispida, 1/57), Arctic fox (Vulpes lagopus, 3-7/32), and polar bear (Ursus maritimus, 1/1), but was not detected in walruses (0/137) regardless of %HTLP in the diet. Walrus blubber and attached skin contained 44.6 ±12.4% lipid wet weight, which was lower than that found for other Arctic marine mammals; however, the inclusion of skin likely decreased our %lipid values. While the absolute value of %lipid from blubber and attached skin was not a suitable substitute for %lipid from blubber only, we were still able to detect the influence of biological factors, with sex-linked variability in walrus lipid stores observed. Cortisol analysis from full-thickness blubber resulted in a wide range of concentrations (2.77 to 34.04 ng/g), but showed that this stress hormone can be extracted from blubber. While neither %lipid nor blubber cortisol was correlated with the proportion of HTLP in walrus diet, they may serve as minimally-invasive methods for health monitoring of ... |
author2 |
Horstmann-Dehn, Lara Atkinson, Shannon Barboza, Perry Rosa, Cheryl Sheffield, Gay Wooller, Matthew |
format |
Doctoral or Postdoctoral Thesis |
author |
Seymour, Jill-Marie |
spellingShingle |
Seymour, Jill-Marie Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
author_facet |
Seymour, Jill-Marie |
author_sort |
Seymour, Jill-Marie |
title |
Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
title_short |
Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
title_full |
Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
title_fullStr |
Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
title_full_unstemmed |
Pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
title_sort |
pacific walrus use of higher trophic level prey and the relation to sea ice extent, body condition, and trichinellosis |
publishDate |
2014 |
url |
http://hdl.handle.net/11122/4566 |
geographic |
Arctic Fairbanks Pacific |
geographic_facet |
Arctic Fairbanks Pacific |
genre |
Arctic Fox Arctic marine mammals Arctic Odobenus rosmarus Pusa hispida ringed seal Sea ice Ursus maritimus Vulpes lagopus Alaska walrus* |
genre_facet |
Arctic Fox Arctic marine mammals Arctic Odobenus rosmarus Pusa hispida ringed seal Sea ice Ursus maritimus Vulpes lagopus Alaska walrus* |
op_relation |
http://hdl.handle.net/11122/4566 Program in Marine Science and Limnology |
_version_ |
1766304906548871168 |