Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella
Summary Two major drivers in population dynamics are bottom‐up processes, such as environmental factors that affect foraging success, and the top‐down impacts of predation. Many populations of marine mammal and seabird species appear to be declining in response to reductions in prey associated with...
Published in: | Journal of Animal Ecology |
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crwiley:10.1111/1365-2656.12059 2024-06-02T07:58:16+00:00 Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella Schwarz, Lisa K. Goebel, Michael E. Costa, Daniel P. Kilpatrick, A. Marm Weimerskirch, Henri 2013 http://dx.doi.org/10.1111/1365-2656.12059 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1365-2656.12059 https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.12059 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Animal Ecology volume 82, issue 4, page 903-911 ISSN 0021-8790 1365-2656 journal-article 2013 crwiley https://doi.org/10.1111/1365-2656.12059 2024-05-03T11:02:44Z Summary Two major drivers in population dynamics are bottom‐up processes, such as environmental factors that affect foraging success, and the top‐down impacts of predation. Many populations of marine mammal and seabird species appear to be declining in response to reductions in prey associated with the bottom‐up effects of climate change. However, predation, which usually occurs at sea and is difficult to observe, may also play a key role. We analysed drivers of population dynamics of Antarctic fur seals Arctocephalus gazella at Cape Shirreff from 1997 to 2009, including a predator that targets pre‐weaned pups and bottom‐up environmental effects in an ecosystem particularly sensitive to small changes in temperature. We use Bayesian mark‐recapture analysis to demonstrate that although large‐scale environmental variability affects annual adult survival and reproduction, first year survival appears to be driving the current decline in this population (as defined by a decline in the annual number of pups born). Although the number of pups increased during the first third of the study, first year survival and recruitment of those pups in later years was very low. Such low survival may be driven by leopard seal Hydrurga leptonyx predation, particularly prior to weaning. Our results suggest that without leopard seal predation, this population would most likely increase in size, despite the observed bottom‐up effects of climate changes on adult vital rates. More broadly, our results show how age‐targeted predation could be a major factor in population decline of K‐selected colonial breeders. Article in Journal/Newspaper Antarc* Antarctic Antarctic Fur Seals Arctocephalus gazella Hydrurga leptonyx Leopard Seal Wiley Online Library Antarctic Cape Shirreff ENVELOPE(-60.800,-60.800,-62.417,-62.417) Hydrurga ENVELOPE(-61.626,-61.626,-64.145,-64.145) Shirreff ENVELOPE(-60.792,-60.792,-62.459,-62.459) Journal of Animal Ecology 82 4 903 911 |
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Open Polar |
collection |
Wiley Online Library |
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crwiley |
language |
English |
description |
Summary Two major drivers in population dynamics are bottom‐up processes, such as environmental factors that affect foraging success, and the top‐down impacts of predation. Many populations of marine mammal and seabird species appear to be declining in response to reductions in prey associated with the bottom‐up effects of climate change. However, predation, which usually occurs at sea and is difficult to observe, may also play a key role. We analysed drivers of population dynamics of Antarctic fur seals Arctocephalus gazella at Cape Shirreff from 1997 to 2009, including a predator that targets pre‐weaned pups and bottom‐up environmental effects in an ecosystem particularly sensitive to small changes in temperature. We use Bayesian mark‐recapture analysis to demonstrate that although large‐scale environmental variability affects annual adult survival and reproduction, first year survival appears to be driving the current decline in this population (as defined by a decline in the annual number of pups born). Although the number of pups increased during the first third of the study, first year survival and recruitment of those pups in later years was very low. Such low survival may be driven by leopard seal Hydrurga leptonyx predation, particularly prior to weaning. Our results suggest that without leopard seal predation, this population would most likely increase in size, despite the observed bottom‐up effects of climate changes on adult vital rates. More broadly, our results show how age‐targeted predation could be a major factor in population decline of K‐selected colonial breeders. |
author2 |
Weimerskirch, Henri |
format |
Article in Journal/Newspaper |
author |
Schwarz, Lisa K. Goebel, Michael E. Costa, Daniel P. Kilpatrick, A. Marm |
spellingShingle |
Schwarz, Lisa K. Goebel, Michael E. Costa, Daniel P. Kilpatrick, A. Marm Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella |
author_facet |
Schwarz, Lisa K. Goebel, Michael E. Costa, Daniel P. Kilpatrick, A. Marm |
author_sort |
Schwarz, Lisa K. |
title |
Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella |
title_short |
Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella |
title_full |
Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella |
title_fullStr |
Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella |
title_full_unstemmed |
Top‐down and bottom‐up influences on demographic rates of Antarctic fur seals Arctocephalus gazella |
title_sort |
top‐down and bottom‐up influences on demographic rates of antarctic fur seals arctocephalus gazella |
publisher |
Wiley |
publishDate |
2013 |
url |
http://dx.doi.org/10.1111/1365-2656.12059 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2F1365-2656.12059 https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/1365-2656.12059 |
long_lat |
ENVELOPE(-60.800,-60.800,-62.417,-62.417) ENVELOPE(-61.626,-61.626,-64.145,-64.145) ENVELOPE(-60.792,-60.792,-62.459,-62.459) |
geographic |
Antarctic Cape Shirreff Hydrurga Shirreff |
geographic_facet |
Antarctic Cape Shirreff Hydrurga Shirreff |
genre |
Antarc* Antarctic Antarctic Fur Seals Arctocephalus gazella Hydrurga leptonyx Leopard Seal |
genre_facet |
Antarc* Antarctic Antarctic Fur Seals Arctocephalus gazella Hydrurga leptonyx Leopard Seal |
op_source |
Journal of Animal Ecology volume 82, issue 4, page 903-911 ISSN 0021-8790 1365-2656 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/1365-2656.12059 |
container_title |
Journal of Animal Ecology |
container_volume |
82 |
container_issue |
4 |
container_start_page |
903 |
op_container_end_page |
911 |
_version_ |
1800741560314232832 |