Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size
Abstract Background Resolving the preferred prey items and dietary proportions of leopard seals is central to understanding food-web dynamics in the rapidly-warming Antarctic Peninsula region. Previous studies have identified a wide range of prey items; however, due to anecdotal or otherwise limited...
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| Format: | Article |
| Language: | English |
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BMC
2020-06-01
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| Series: | BMC Ecology |
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| Online Access: | http://link.springer.com/article/10.1186/s12898-020-00300-y |
| _version_ | 1819127425572798464 |
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| author | Douglas J. Krause Michael E. Goebel Carolyn M. Kurle |
| author_facet | Douglas J. Krause Michael E. Goebel Carolyn M. Kurle |
| author_sort | Douglas J. Krause |
| collection | DOAJ |
| description | Abstract Background Resolving the preferred prey items and dietary proportions of leopard seals is central to understanding food-web dynamics in the rapidly-warming Antarctic Peninsula region. Previous studies have identified a wide range of prey items; however, due to anecdotal or otherwise limited information, leopard seal diets remain unresolved by seal sex, individual, body size, region, and season. Over the 2013, 2014, and 2017 field seasons we collected scat, tissue samples (red blood cells and plasma; n = 23) for stable isotope analyses, and previously-reported animal-borne video from 19 adult leopard seals foraging near mesopredator breeding colonies at Cape Shirreff, Livingston Island. We summarized a priori diet information from scat and video analysis and applied a three-isotope (δ 13C, δ 15N, δ 34S), four-source (fish, fur seal, krill, penguin) Bayesian mixing model to examine temporal variability in both prey sources and leopard seal tissues. Results The austral spring diets of males and females focused on Antarctic krill (31.7–38.0%), notothen fish (31.6–36.5%), and penguin (24.4–26.9%) and were consistent across all 3 years. Several lines of evidence suggest the transition to summer foraging was distinct for males and females. Female diets transitioned rapidly to higher δ 15N values (+2.1‰), indicating increased consumption of penguin (29.5–46.2%) and energy-dense Antarctic fur seal pup (21.3–37.6%). Conclusions The seasonal increase in leopard seal δ 15N values, and thus fur seal in their diet, was predictably related to larger body size; it may also be forcing reductions to the largest Antarctic fur seal colony in the Antarctic Peninsula. Our ensemble sampling approach reduces historical biases in monitoring marine apex predator diets. Further, our results are necessary to best inform regional fisheries management planning. |
| first_indexed | 2024-12-22T08:11:44Z |
| format | Article |
| id | doaj.art-89350cdc2b864ba7ace881df920af664 |
| institution | Directory Open Access Journal |
| issn | 1472-6785 |
| language | English |
| last_indexed | 2024-12-22T08:11:44Z |
| publishDate | 2020-06-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Ecology |
| spelling | doaj.art-89350cdc2b864ba7ace881df920af6642022-12-21T18:33:01ZengBMCBMC Ecology1472-67852020-06-0120111510.1186/s12898-020-00300-yLeopard seal diets in a rapidly warming polar region vary by year, season, sex, and body sizeDouglas J. Krause0Michael E. Goebel1Carolyn M. Kurle2Antarctic Ecosystem Research Division, NOAA Fisheries-Southwest Fisheries Science CenterAntarctic Ecosystem Research Division, NOAA Fisheries-Southwest Fisheries Science CenterDivsion of Biological Sciences, University of California San DiegoAbstract Background Resolving the preferred prey items and dietary proportions of leopard seals is central to understanding food-web dynamics in the rapidly-warming Antarctic Peninsula region. Previous studies have identified a wide range of prey items; however, due to anecdotal or otherwise limited information, leopard seal diets remain unresolved by seal sex, individual, body size, region, and season. Over the 2013, 2014, and 2017 field seasons we collected scat, tissue samples (red blood cells and plasma; n = 23) for stable isotope analyses, and previously-reported animal-borne video from 19 adult leopard seals foraging near mesopredator breeding colonies at Cape Shirreff, Livingston Island. We summarized a priori diet information from scat and video analysis and applied a three-isotope (δ 13C, δ 15N, δ 34S), four-source (fish, fur seal, krill, penguin) Bayesian mixing model to examine temporal variability in both prey sources and leopard seal tissues. Results The austral spring diets of males and females focused on Antarctic krill (31.7–38.0%), notothen fish (31.6–36.5%), and penguin (24.4–26.9%) and were consistent across all 3 years. Several lines of evidence suggest the transition to summer foraging was distinct for males and females. Female diets transitioned rapidly to higher δ 15N values (+2.1‰), indicating increased consumption of penguin (29.5–46.2%) and energy-dense Antarctic fur seal pup (21.3–37.6%). Conclusions The seasonal increase in leopard seal δ 15N values, and thus fur seal in their diet, was predictably related to larger body size; it may also be forcing reductions to the largest Antarctic fur seal colony in the Antarctic Peninsula. Our ensemble sampling approach reduces historical biases in monitoring marine apex predator diets. Further, our results are necessary to best inform regional fisheries management planning.http://link.springer.com/article/10.1186/s12898-020-00300-yStable isotope mixing modelApex predatorTop downPrey shiftHydrurga leptonyxClimate change |
| spellingShingle | Douglas J. Krause Michael E. Goebel Carolyn M. Kurle Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size BMC Ecology Stable isotope mixing model Apex predator Top down Prey shift Hydrurga leptonyx Climate change |
| title | Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size |
| title_full | Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size |
| title_fullStr | Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size |
| title_full_unstemmed | Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size |
| title_short | Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size |
| title_sort | leopard seal diets in a rapidly warming polar region vary by year season sex and body size |
| topic | Stable isotope mixing model Apex predator Top down Prey shift Hydrurga leptonyx Climate change |
| url | http://link.springer.com/article/10.1186/s12898-020-00300-y |
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