Details:

Journal Title:
Marine Ecology Progress Series
Personal Author:
Feddern, M.L. ; Ward, E.J. ; Warlick, A.J. ; Holtgrieve, G.W.
Feddern, M.L. ; Ward, E.J. ; Warlick, A.J. ; Holtgrieve, G.W. Less -
NOAA Program & Office:
NMFS (National Marine Fisheries Service) ; NWFSC (Northwest Fisheries Science Center)
NMFS (National Marine Fisheries Service) ; NWFSC (Northwest Fisheries Science Center) Less -
Description:
Over the past century, Alaskan pinnipeds have experienced dramatic changes in abundance, but these changes have been highly variable across species and regions. In recent decades, changes in atmospheric forcing and sea surface temperature have been particularly pronounced in the Gulf of Alaska and eastern Bering Sea, impacting the food webs in which Alaskan pinnipeds forage. We used compound-specific stable isotope analysis of nitrogen in amino acids to estimate historic and modern trophic positions of harbor seals Phoca vitulina and Steller sea lions Eumetopias jubatus in the Gulf of Alaska and Bristol Bay. We applied a Bayesian hierarchical framework to determine whether shared trends through time exist across pinnipeds (classified by region and species) on decadal scales. Model results identified both shared trends through time and classification-specific decadal changes in pinniped trophic position. The largest change in trophic position occurred in the 2000s and 2010s and was observed in both Steller sea lions (median: 2.8) and harbor seals (median: 3.1) in the Gulf of Alaska, but not harbor seals in Bristol Bay or Iliamna Lake. Divergent trophic position patterns in the 2000s were identified in the western stock of Steller sea lions, which increased in trophic position, and sympatric harbor seals in the northern Gulf of Alaska, which decreased in trophic position. Our results indicate that these species have been experiencing unique food web conditions in recent decades in the Gulf of Alaska, likely in response to recent climate-induced ecological change in the region.
Keywords:
[+]
Harbor Seal
Steller's Sea Lion
Compound-specific Stable Isotope Analysis
Eumetopias Jubatus
Phoca Vitulina
Steller Sea Lion
Trophic Position

Source:
Mar Ecol Prog Ser 688:153-166
DOI:
https://doi.org/10.3354/meps14014
Document Type:
Journal Article
Funding:
Grant no. NA18OAR4170095 ; Grant no. NA19OAR4170360 ; Grant no. NA15OAR4320063
Grant no. NA18OAR4170095 ; Grant no. NA19OAR4170360 ; Grant no. NA15OAR4320063 Less -
Rights Information:
Accepted Manuscript
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:cd91dbb415f92e1d4884ccbadeaf02ce2105018ac52de24ac2d7c36ed92d7118
File Type:

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