Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator
We applied a 2-step clustering algorithm and Bayesian stable isotope mixing model to examine intraspecific differences in the contribution of prey sources to the diet and foraging habitat of harbor seals Phoca vitulina in the Salish Sea, USA. We analyzed stable isotopes of carbon and nitrogen collec...
Published in: | Marine Ecology Progress Series |
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Inter Research
2015
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Online Access: | https://oceanrep.geomar.de/id/eprint/30559/ https://oceanrep.geomar.de/id/eprint/30559/1/Bjorkland.pdf https://doi.org/10.3354/meps11230 |
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ftoceanrep:oai:oceanrep.geomar.de:30559 2023-05-15T15:56:09+02:00 Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator Bjorkland, R.H. Pearson, S.F. Jeffries, S.J. Lance, M.M. Acevedo-Gutiérrez, A. Ward, E.J. 2015 text https://oceanrep.geomar.de/id/eprint/30559/ https://oceanrep.geomar.de/id/eprint/30559/1/Bjorkland.pdf https://doi.org/10.3354/meps11230 en eng Inter Research https://oceanrep.geomar.de/id/eprint/30559/1/Bjorkland.pdf Bjorkland, R. H., Pearson, S. F., Jeffries, S. J., Lance, M. M., Acevedo-Gutiérrez, A. and Ward, E. J. (2015) Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator. Marine Ecology Progress Series, 526 . pp. 213-225. DOI 10.3354/meps11230 <https://doi.org/10.3354/meps11230>. doi:10.3354/meps11230 Article PeerReviewed 2015 ftoceanrep https://doi.org/10.3354/meps11230 2023-04-07T15:22:19Z We applied a 2-step clustering algorithm and Bayesian stable isotope mixing model to examine intraspecific differences in the contribution of prey sources to the diet and foraging habitat of harbor seals Phoca vitulina in the Salish Sea, USA. We analyzed stable isotopes of carbon and nitrogen collected from 32 seals and 248 prey samples representing 18 of 25 of the most common seal prey items identified in seal scat. Stable isotope analyses identified significant harbor seal sex- and size-based differences in diet and foraging habitat use. In comparison to males, female harbor seals had a higher contribution of prey items that were more 13C-enriched. This result may indicate that females derived more of their δ13C value from nearshore versus offshore food webs, an explanation supported by movement data on this population. However, large seals of both sexes displayed a greater offshore signal in their diet, indicating that seal mass effects on foraging habitat use were somewhat independent of sex. Our work contributes to understanding trophic linkages between these generalist consumers and their prey. The foraging differences that we detected between male and female harbor seals present complex challenges for fisheries management and for the design of marine reserves. Many marine reserves in the Pacific Northwest are located in close proximity to seal haul-out sites. By lowering the energetic costs of foraging of females, these reserves may ultimately have the unintended effect of increasing individual fitness, population growth rate, and influencing future predator-induced mortality on endangered species. Article in Journal/Newspaper common seal harbor seal Phoca vitulina OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Pacific Marine Ecology Progress Series 526 213 225 |
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Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
We applied a 2-step clustering algorithm and Bayesian stable isotope mixing model to examine intraspecific differences in the contribution of prey sources to the diet and foraging habitat of harbor seals Phoca vitulina in the Salish Sea, USA. We analyzed stable isotopes of carbon and nitrogen collected from 32 seals and 248 prey samples representing 18 of 25 of the most common seal prey items identified in seal scat. Stable isotope analyses identified significant harbor seal sex- and size-based differences in diet and foraging habitat use. In comparison to males, female harbor seals had a higher contribution of prey items that were more 13C-enriched. This result may indicate that females derived more of their δ13C value from nearshore versus offshore food webs, an explanation supported by movement data on this population. However, large seals of both sexes displayed a greater offshore signal in their diet, indicating that seal mass effects on foraging habitat use were somewhat independent of sex. Our work contributes to understanding trophic linkages between these generalist consumers and their prey. The foraging differences that we detected between male and female harbor seals present complex challenges for fisheries management and for the design of marine reserves. Many marine reserves in the Pacific Northwest are located in close proximity to seal haul-out sites. By lowering the energetic costs of foraging of females, these reserves may ultimately have the unintended effect of increasing individual fitness, population growth rate, and influencing future predator-induced mortality on endangered species. |
format |
Article in Journal/Newspaper |
author |
Bjorkland, R.H. Pearson, S.F. Jeffries, S.J. Lance, M.M. Acevedo-Gutiérrez, A. Ward, E.J. |
spellingShingle |
Bjorkland, R.H. Pearson, S.F. Jeffries, S.J. Lance, M.M. Acevedo-Gutiérrez, A. Ward, E.J. Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
author_facet |
Bjorkland, R.H. Pearson, S.F. Jeffries, S.J. Lance, M.M. Acevedo-Gutiérrez, A. Ward, E.J. |
author_sort |
Bjorkland, R.H. |
title |
Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
title_short |
Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
title_full |
Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
title_fullStr |
Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
title_full_unstemmed |
Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
title_sort |
stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator |
publisher |
Inter Research |
publishDate |
2015 |
url |
https://oceanrep.geomar.de/id/eprint/30559/ https://oceanrep.geomar.de/id/eprint/30559/1/Bjorkland.pdf https://doi.org/10.3354/meps11230 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
common seal harbor seal Phoca vitulina |
genre_facet |
common seal harbor seal Phoca vitulina |
op_relation |
https://oceanrep.geomar.de/id/eprint/30559/1/Bjorkland.pdf Bjorkland, R. H., Pearson, S. F., Jeffries, S. J., Lance, M. M., Acevedo-Gutiérrez, A. and Ward, E. J. (2015) Stable isotope mixing models elucidate sex and size effects on the diet of a generalist marine predator. Marine Ecology Progress Series, 526 . pp. 213-225. DOI 10.3354/meps11230 <https://doi.org/10.3354/meps11230>. doi:10.3354/meps11230 |
op_doi |
https://doi.org/10.3354/meps11230 |
container_title |
Marine Ecology Progress Series |
container_volume |
526 |
container_start_page |
213 |
op_container_end_page |
225 |
_version_ |
1766391618989981696 |