Biogeochemical tracers of change in Pacific walruses past and present
Dissertation (Ph.D.) University of Alaska Fairbanks, 2019 Reduced sea ice and projected food web shifts associated with warming of the Arctic have raised concerns about the future of Arctic species. Pacific walruses (Odobenus rosmarus divergens) use sea ice as a platform for molting, giving birth, a...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/10485 2023-05-15T14:56:55+02:00 Biogeochemical tracers of change in Pacific walruses past and present Clark, Casey Horstmann, Lara Misarti, Nicole Konar, Brenda Severin, Ken Lemons, Patrick 2019-05 http://hdl.handle.net/11122/10485 en_US eng http://hdl.handle.net/11122/10485 Department of Marine Biology walrus global warming food nutrition habitat stress Bering Sea sea ice Chukchi Sea Dissertation phd 2019 ftunivalaska 2023-02-23T21:37:29Z Dissertation (Ph.D.) University of Alaska Fairbanks, 2019 Reduced sea ice and projected food web shifts associated with warming of the Arctic have raised concerns about the future of Arctic species. Pacific walruses (Odobenus rosmarus divergens) use sea ice as a platform for molting, giving birth, and resting between foraging bouts. Exactly how sea ice loss will affect walruses is difficult to predict, due to a lack of information about regional ecosystems and their responses to climate change. The objectives of the research in this dissertation were to 1) examine how walrus diet changed in response to shifting sea ice conditions over the last 4,000 years, with the goal of generating predictions about how current and future ice loss may affect the walrus population; 2) make it easier to directly compare the results of retrospective and contemporary stable isotope studies of walruses; and 3) generate new tools to assist wildlife managers in monitoring the walrus population in an uncertain future. Stable carbon and nitrogen isotope ratios of walrus bone collagen indicated that diet was similar during previous intervals of high and low sea ice; however, diet variability among individual walruses was greater when sea ice cover was low, suggesting decreased abundance of preferred mollusk prey. Modern walrus diet was different from both previous high and low ice intervals, meaning that food webs in the Arctic are still in a state of flux, or that recent changes are novel within the last 4,000 years. Tissue-specific stable isotope discrimination factors were generated for walrus muscle, liver, skin, and bone collagen to improve comparisons between retrospective and contemporary studies of walrus diet. Additionally, lipid normalization models were parameterized for walrus skin and muscle, thereby making future walrus stable isotope research more feasible by reducing analytical costs and allowing the use of non-lethal sample collection. Finally, a novel technique for estimating the age at onset of reproductive maturity ... Doctoral or Postdoctoral Thesis Arctic Bering Sea Chukchi Chukchi Sea Climate change Global warming Odobenus rosmarus Sea ice Alaska walrus* University of Alaska: ScholarWorks@UA Arctic Bering Sea Chukchi Sea Fairbanks Pacific |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
walrus global warming food nutrition habitat stress Bering Sea sea ice Chukchi Sea |
spellingShingle |
walrus global warming food nutrition habitat stress Bering Sea sea ice Chukchi Sea Clark, Casey Biogeochemical tracers of change in Pacific walruses past and present |
topic_facet |
walrus global warming food nutrition habitat stress Bering Sea sea ice Chukchi Sea |
description |
Dissertation (Ph.D.) University of Alaska Fairbanks, 2019 Reduced sea ice and projected food web shifts associated with warming of the Arctic have raised concerns about the future of Arctic species. Pacific walruses (Odobenus rosmarus divergens) use sea ice as a platform for molting, giving birth, and resting between foraging bouts. Exactly how sea ice loss will affect walruses is difficult to predict, due to a lack of information about regional ecosystems and their responses to climate change. The objectives of the research in this dissertation were to 1) examine how walrus diet changed in response to shifting sea ice conditions over the last 4,000 years, with the goal of generating predictions about how current and future ice loss may affect the walrus population; 2) make it easier to directly compare the results of retrospective and contemporary stable isotope studies of walruses; and 3) generate new tools to assist wildlife managers in monitoring the walrus population in an uncertain future. Stable carbon and nitrogen isotope ratios of walrus bone collagen indicated that diet was similar during previous intervals of high and low sea ice; however, diet variability among individual walruses was greater when sea ice cover was low, suggesting decreased abundance of preferred mollusk prey. Modern walrus diet was different from both previous high and low ice intervals, meaning that food webs in the Arctic are still in a state of flux, or that recent changes are novel within the last 4,000 years. Tissue-specific stable isotope discrimination factors were generated for walrus muscle, liver, skin, and bone collagen to improve comparisons between retrospective and contemporary studies of walrus diet. Additionally, lipid normalization models were parameterized for walrus skin and muscle, thereby making future walrus stable isotope research more feasible by reducing analytical costs and allowing the use of non-lethal sample collection. Finally, a novel technique for estimating the age at onset of reproductive maturity ... |
author2 |
Horstmann, Lara Misarti, Nicole Konar, Brenda Severin, Ken Lemons, Patrick |
format |
Doctoral or Postdoctoral Thesis |
author |
Clark, Casey |
author_facet |
Clark, Casey |
author_sort |
Clark, Casey |
title |
Biogeochemical tracers of change in Pacific walruses past and present |
title_short |
Biogeochemical tracers of change in Pacific walruses past and present |
title_full |
Biogeochemical tracers of change in Pacific walruses past and present |
title_fullStr |
Biogeochemical tracers of change in Pacific walruses past and present |
title_full_unstemmed |
Biogeochemical tracers of change in Pacific walruses past and present |
title_sort |
biogeochemical tracers of change in pacific walruses past and present |
publishDate |
2019 |
url |
http://hdl.handle.net/11122/10485 |
geographic |
Arctic Bering Sea Chukchi Sea Fairbanks Pacific |
geographic_facet |
Arctic Bering Sea Chukchi Sea Fairbanks Pacific |
genre |
Arctic Bering Sea Chukchi Chukchi Sea Climate change Global warming Odobenus rosmarus Sea ice Alaska walrus* |
genre_facet |
Arctic Bering Sea Chukchi Chukchi Sea Climate change Global warming Odobenus rosmarus Sea ice Alaska walrus* |
op_relation |
http://hdl.handle.net/11122/10485 Department of Marine Biology |
_version_ |
1766328967728463872 |