Fortuitous encounters between seagliders and adult female northern fur seals ( Callorhinus ursinus ) off the Washington (USA) Coast: Upper ocean variability and links to top predator behavior
Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastaltopography suggest that biophysical interactions in these zones affect predators prey, foraging behaviors, and potentiallyfitness. However, examining these pathways is challenged b...
Published in: | PLoS ONE |
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Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Public Library of Science
2014
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Subjects: | |
Online Access: | https://doi.org/10.1371/journal.pone.0101268 http://www.ncbi.nlm.nih.gov/pubmed/25153524 http://ecite.utas.edu.au/95644 |
Summary: | Behavioral responses by top marine predators to oceanographic features such as eddies, river plumes, storms, and coastaltopography suggest that biophysical interactions in these zones affect predators prey, foraging behaviors, and potentiallyfitness. However, examining these pathways is challenged by the obstacles inherent in obtaining simultaneous observationsof surface and subsurface environmental fields and predator behavior. In this study, migratory movements and, in somecases, diving behavior of 40 adult female northern fur seals (NFS; Callorhinus ursinus ) were quantified across their range andcompared to remotely-sensed environmental data in the Gulf of Alaska and California Current ecosystems, with a particularfocus off the coast of Washington State (USA) a known foraging ground for adult female NFS and where autonomousglider sampling allowed opportunistic comparison of seal behavior to subsurface biophysical measurements. The resultsshow that in these ecosystems, adult female habitat utilization was concentrated near prominent coastal topographic,riverine, or inlet features and within 200 km of the continental shelf break. Seal dive depths, in most ecosystems, weremoderated by surface light level (solar or lunar), mirroring known behaviors of diel vertically-migrating prey. However, sealdives differed in the California Current ecosystem due to a shift to more daytime diving concentrated at or below thesurface mixed layer base. Seal movement models indicate behavioral responses to season, ecosystem, and surface windspeeds; individuals also responded to mesoscale eddies, jets, and the Columbia River plume. Foraging within small scalesurface features is consistent with utilization of the inner coastal transition zone and habitats near coastal capes, which areknown eddy and filament generation sites. These results contribute to our knowledge of NFS migratory patterns bydemonstrating surface and subsurface behavioral responses to a spatially and temporally dynamic ocean environment, thusreflecting its influence on associated NFS prey species. |
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