Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene
Abstract The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well‐known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lu...
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doaj-46b59a46583d4fb88a261bedcd10330e2021-03-02T07:47:37ZengWileyEcology and Evolution2045-77582020-04-011073318332910.1002/ece3.6114Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the AnthropoceneEmma A. Elliott Smith0Martin Tim Tinker1Emily L. Whistler2Douglas J. Kennett3René L. Vellanoweth4Diane Gifford‐Gonzalez5Mark G. Hylkema6Seth D. Newsome7Department of Biology University of New Mexico Albuquerque NM USANhydra Ecological Consulting St Margaret’s Bay Nova Scotia CanadaDepartment of Anthropology Washington State University Pullman WA USADepartment of Anthropology University of California Santa Barbara CA USADepartment of Anthropology California State University Los Angeles Los Angeles CA USADepartment of Anthropology University of California Santa Cruz Santa Cruz CA USACalifornia Department of Parks and Recreation Santa Cruz CA USADepartment of Biology University of New Mexico Albuquerque NM USAAbstract The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well‐known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ13C analysis and δ15N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ15N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue‐specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ15N values than modern populations. Amino acid δ15N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts.https://doi.org/10.1002/ece3.6114amino acid stable isotope analysishistorical ecologymarine ecologymarine mammal conservationstable isotopeszooarchaeology |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Emma A. Elliott Smith Martin Tim Tinker Emily L. Whistler Douglas J. Kennett René L. Vellanoweth Diane Gifford‐Gonzalez Mark G. Hylkema Seth D. Newsome |
spellingShingle |
Emma A. Elliott Smith Martin Tim Tinker Emily L. Whistler Douglas J. Kennett René L. Vellanoweth Diane Gifford‐Gonzalez Mark G. Hylkema Seth D. Newsome Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene Ecology and Evolution amino acid stable isotope analysis historical ecology marine ecology marine mammal conservation stable isotopes zooarchaeology |
author_facet |
Emma A. Elliott Smith Martin Tim Tinker Emily L. Whistler Douglas J. Kennett René L. Vellanoweth Diane Gifford‐Gonzalez Mark G. Hylkema Seth D. Newsome |
author_sort |
Emma A. Elliott Smith |
title |
Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene |
title_short |
Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene |
title_full |
Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene |
title_fullStr |
Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene |
title_full_unstemmed |
Reductions in the dietary niche of southern sea otters (Enhydra lutris nereis) from the Holocene to the Anthropocene |
title_sort |
reductions in the dietary niche of southern sea otters (enhydra lutris nereis) from the holocene to the anthropocene |
publisher |
Wiley |
series |
Ecology and Evolution |
issn |
2045-7758 |
publishDate |
2020-04-01 |
description |
Abstract The sea otter (Enhydra lutris) is a marine mammal hunted to near extinction during the 1800s. Despite their well‐known modern importance as a keystone species, we know little about historical sea otter ecology. Here, we characterize the ecological niche of ancient southern sea otters (E. lutris nereis) using δ13C analysis and δ15N analysis of bones recovered from archaeological sites spanning ~7,000 to 350 years before present (N = 112 individuals) at five regions along the coast of California. These data are compared with previously published data on modern animals (N = 165) and potential modern prey items. In addition, we analyze the δ15N of individual amino acids for 23 individuals to test for differences in sea otter trophic ecology through time. After correcting for tissue‐specific and temporal isotopic effects, we employ nonparametric statistics and Bayesian niche models to quantify differences among ancient and modern animals. We find ancient otters occupied a larger isotopic niche than nearly all modern localities; likely reflecting broader habitat and prey use in prefur trade populations. In addition, ancient sea otters at the most southerly sites occupied an isotopic niche that was more than twice as large as ancient otters from northerly regions. This likely reflects greater invertebrate prey diversity in southern California relative to northern California. Thus, we suggest the potential dietary niche of sea otters in southern California could be larger than in central and northern California. At two sites, Año Nuevo and Monterey Bay, ancient otters had significantly higher δ15N values than modern populations. Amino acid δ15N data indicated this resulted from shifting baseline isotope values, rather than a change in sea otter trophic ecology. Our results help in better understanding the contemporary ecological role of sea otters and exemplify the strength of combing zooarchaeological and biological information to provide baseline data for conservation efforts. |
topic |
amino acid stable isotope analysis historical ecology marine ecology marine mammal conservation stable isotopes zooarchaeology |
url |
https://doi.org/10.1002/ece3.6114 |
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