Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios
Dissertation (Ph.D.) University of Alaska Fairbanks, 2001 Trophic changes in populations of Stellar sea lions (Eumetorias jubatus), northern fur seals (Callorhinus ursinus) and harbor seals (Phoca vitulina) in the eastern Bering Sea and Gulf of Alaska were studied using stable isotope analysis. Decl...
Main Author: | |
---|---|
Other Authors: | , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | English |
Published: |
2001
|
Subjects: | |
Online Access: | http://hdl.handle.net/11122/4830 |
id |
ftunivalaska:oai:scholarworks.alaska.edu:11122/4830 |
---|---|
record_format |
openpolar |
spelling |
ftunivalaska:oai:scholarworks.alaska.edu:11122/4830 2023-05-15T15:43:59+02:00 Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios Hirons, Amy Christia Schell, Donald Castellini, Michael Cooney, Theodore Springer, Alan Barry, Ronald 2001-05 http://hdl.handle.net/11122/4830 en_US eng http://hdl.handle.net/11122/4830 Marine Science and Limnology Dissertation phd 2001 ftunivalaska 2023-02-23T21:36:17Z Dissertation (Ph.D.) University of Alaska Fairbanks, 2001 Trophic changes in populations of Stellar sea lions (Eumetorias jubatus), northern fur seals (Callorhinus ursinus) and harbor seals (Phoca vitulina) in the eastern Bering Sea and Gulf of Alaska were studied using stable isotope analysis. Declining populations of all three species of pinnipeds prompted this study to determine if changes in diet, likely resulting from food limitation, contributed to the declines. Stable carbon and nitrogen isotope ratios were analyzed in the vibrissae (whiskers) and body tissues of pinnipeds from 1993-1998 and compared with muscle tissue from prey species during the same time period to determine pinniped trophic dynamics. Vibrissae growth rate studies revealed harbor seal vibrissae are only retained for one year and then replaced, while Steller sea lions maintain their vibrissae for several years. Isotopic data from all three species are consistent with diets composed of walleye pollock (Theragra chalcogramma) at various times and locations throughout the year. Steller sea lion and northern fur seal vibrissae revealed regular oscillations along their lengths in both carbon and nitrogen isotope ratios that likely corresponded to regional isotopic differences. As these animals moved or migrated from one region to another during the year, they metabolically incorporated the different regional isotope ratios through their prey. Because these animals return to their rookery to pup, breed and molt each year, the isotope ratios in the vibrissae showed a regular pattern of enrichment and deplection. Harbor seals, which tend to stay in one geographic location, have relatively static isotope ratios in their vibrissae, while seals that moved into offshore waters had fluctuating isotope ratios that corresponded to regional difference. No trophic shifts, as evidenced by major changes in nitrogen isotope ratios, were present in any tissues from the three species over the period 1975-1998. Stable isotope ratios of bone collagen for all ... Doctoral or Postdoctoral Thesis Bering Sea harbor seal Phoca vitulina Theragra chalcogramma Alaska Callorhinus ursinus Northern fur seal University of Alaska: ScholarWorks@UA Bering Sea Fairbanks Gulf of Alaska |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
description |
Dissertation (Ph.D.) University of Alaska Fairbanks, 2001 Trophic changes in populations of Stellar sea lions (Eumetorias jubatus), northern fur seals (Callorhinus ursinus) and harbor seals (Phoca vitulina) in the eastern Bering Sea and Gulf of Alaska were studied using stable isotope analysis. Declining populations of all three species of pinnipeds prompted this study to determine if changes in diet, likely resulting from food limitation, contributed to the declines. Stable carbon and nitrogen isotope ratios were analyzed in the vibrissae (whiskers) and body tissues of pinnipeds from 1993-1998 and compared with muscle tissue from prey species during the same time period to determine pinniped trophic dynamics. Vibrissae growth rate studies revealed harbor seal vibrissae are only retained for one year and then replaced, while Steller sea lions maintain their vibrissae for several years. Isotopic data from all three species are consistent with diets composed of walleye pollock (Theragra chalcogramma) at various times and locations throughout the year. Steller sea lion and northern fur seal vibrissae revealed regular oscillations along their lengths in both carbon and nitrogen isotope ratios that likely corresponded to regional isotopic differences. As these animals moved or migrated from one region to another during the year, they metabolically incorporated the different regional isotope ratios through their prey. Because these animals return to their rookery to pup, breed and molt each year, the isotope ratios in the vibrissae showed a regular pattern of enrichment and deplection. Harbor seals, which tend to stay in one geographic location, have relatively static isotope ratios in their vibrissae, while seals that moved into offshore waters had fluctuating isotope ratios that corresponded to regional difference. No trophic shifts, as evidenced by major changes in nitrogen isotope ratios, were present in any tissues from the three species over the period 1975-1998. Stable isotope ratios of bone collagen for all ... |
author2 |
Schell, Donald Castellini, Michael Cooney, Theodore Springer, Alan Barry, Ronald |
format |
Doctoral or Postdoctoral Thesis |
author |
Hirons, Amy Christia |
spellingShingle |
Hirons, Amy Christia Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios |
author_facet |
Hirons, Amy Christia |
author_sort |
Hirons, Amy Christia |
title |
Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios |
title_short |
Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios |
title_full |
Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios |
title_fullStr |
Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios |
title_full_unstemmed |
Trophic dynamics of pinniped populations in Alaska using stable carbon and nitrogen isotope ratios |
title_sort |
trophic dynamics of pinniped populations in alaska using stable carbon and nitrogen isotope ratios |
publishDate |
2001 |
url |
http://hdl.handle.net/11122/4830 |
geographic |
Bering Sea Fairbanks Gulf of Alaska |
geographic_facet |
Bering Sea Fairbanks Gulf of Alaska |
genre |
Bering Sea harbor seal Phoca vitulina Theragra chalcogramma Alaska Callorhinus ursinus Northern fur seal |
genre_facet |
Bering Sea harbor seal Phoca vitulina Theragra chalcogramma Alaska Callorhinus ursinus Northern fur seal |
op_relation |
http://hdl.handle.net/11122/4830 Marine Science and Limnology |
_version_ |
1766378207087427584 |