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dc.contributor.authorRode, Karyn D.
dc.contributor.authorWilson, Ryan R.
dc.contributor.authorDouglas, David C.
dc.contributor.authorMuhlenbruch, Vanessa
dc.contributor.authorAtwood, Todd C.
dc.contributor.authorRegehr, Eric V.
dc.contributor.authorRichardson, Evan S.
dc.contributor.authorPilfold, Nicholas W.
dc.contributor.authorDerocher, Andrew E.
dc.contributor.authorDurner, George M.
dc.contributor.authorStirling, Ian
dc.contributor.authorAmstrup, Steven C.
dc.contributor.authorSt. Martin, Michelle
dc.contributor.authorPagano, Anthony M.
dc.contributor.authorSimac, Kristin
dc.date.accessioned2020-05-27T23:08:25Z
dc.date.available2020-05-27T23:08:25Z
dc.date.issued2018
dc.identifier1365-2486
dc.identifier.doi10.1111/gcb.13933
dc.identifier.urihttp://hdl.handle.net/20.500.12634/260
dc.descriptionSummary: It is well established that long-term changes to sea ice have negative impacts on polar bear body condition, reproduction, and survival. However, it is unclear how changes to ecosystem productivity impact polar bears on shorter time scales. We used blood samples from 1,177 polar bears in the Chukchi and Beaufort Seas in the United States and Canada in spring (1983-2016) to assess whether polar bears were in a fasting state. Fasting rates were found to be correlated with an index of ringed seal productivity. As ringed seals are the primary prey item of polar bears, these results suggest that years with better foraging conditions for ringed seals are also better for polar bear hunting success. This study represents the first broad scale assessment of ecosystem dynamics linking multiple trophic levels, and is a significant step forward in understanding the ecosystem mechanisms that regulate polar bear populations. [in email from Nick Pilford, 11/6/2017]</p>; <p>Summary: It is well established that long-term changes to sea ice have negative impacts on polar bear body condition, reproduction, and survival. However, it is unclear how changes to ecosystem productivity impact polar bears on shorter time scales. We used blood samples from 1,177 polar bears in the Chukchi and Beaufort Seas in the United States and Canada in spring (1983-2016) to assess whether polar bears were in a fasting state. Fasting rates were found to be correlated with an index of ringed seal productivity. As ringed seals are the primary prey item of polar bears, these results suggest that years with better foraging conditions for ringed seals are also better for polar bear hunting success. This study represents the first broad scale assessment of ecosystem dynamics linking multiple trophic levels, and is a significant step forward in understanding the ecosystem mechanisms that regulate polar bear populations.
dc.description.abstractThe effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter-specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic-feeding ice-associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (?7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983–1999 and 2000–2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic-level productivity in these marine ecosystems.
dc.language.isoen
dc.relation.urlhttp://onlinelibrary.wiley.com/doi/10.1111/gcb.13933/abstract
dc.rightsThis article is a U.S. Government work and is in the public domain in the USA.
dc.subjectPOLAR BEARS
dc.subjectFEEDING
dc.subjectBEHAVIOR
dc.subjectECOSYSTEMS
dc.subjectPHYSIOLOGY
dc.subjectARCTIC
dc.subjectCANADA
dc.subjectHUNTING
dc.subjectSEALS
dc.titleSpring fasting behavior in a marine apex predator provides an index of ecosystem productivity
dc.typeArticle
dc.source.journaltitleGlobal Change Biology
dc.source.volume24
dc.source.issue1
dc.source.beginpage410
dc.source.endpage423
refterms.dateFOA2020-05-27T23:08:25Z
html.description.abstractThe effects of declining Arctic sea ice on local ecosystem productivity are not well understood but have been shown to vary inter-specifically, spatially, and temporally. Because marine mammals occupy upper trophic levels in Arctic food webs, they may be useful indicators for understanding variation in ecosystem productivity. Polar bears (Ursus maritimus) are apex predators that primarily consume benthic and pelagic-feeding ice-associated seals. As such, their productivity integrates sea ice conditions and the ecosystem supporting them. Declining sea ice availability has been linked to negative population effects for polar bears but does not fully explain observed population changes. We examined relationships between spring foraging success of polar bears and sea ice conditions, prey productivity, and general patterns of ecosystem productivity in the Beaufort and Chukchi Seas (CSs). Fasting status (?7 days) was estimated using serum urea and creatinine levels of 1,448 samples collected from 1,177 adult and subadult bears across three subpopulations. Fasting increased in the Beaufort Sea between 1983–1999 and 2000–2016 and was related to an index of ringed seal body condition. This change was concurrent with declines in body condition of polar bears and observed changes in the diet, condition and/or reproduction of four other vertebrate consumers within the food chain. In contrast, fasting declined in CS polar bears between periods and was less common than in the two Beaufort Sea subpopulations consistent with studies demonstrating higher primary productivity and maintenance or improved body condition in polar bears, ringed seals, and bearded seals despite recent sea ice loss in this region. Consistency between regional and temporal variation in spring polar bear fasting and food web productivity suggests that polar bears may be a useful indicator species. Furthermore, our results suggest that spatial and temporal ecological variation is important in affecting upper trophic-level productivity in these marine ecosystems.


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