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Krill biomass and aggregation structure in relation to tidal cycle in a penguin foraging region off the Western Antarctic Peninsula

ScholarsArchive at Oregon State University

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Title Krill biomass and aggregation structure in relation to tidal cycle in a penguin foraging region off the Western Antarctic Peninsula
Names Bernard, Kim S. (creator)
Steinberg, Deborah K. (creator)
Date Issued 2013-07 (iso8601)
Note This is a pre-copy-editing, author-produced PDF of an article accepted for publication in ICES Journal of Marine Science following peer review. The definitive publisher-authenticated version, Bernard, K.S., & Steinberg, D.K. (2013). Krill biomass and aggregation structure in relation to tidal cycle in a penguin foraging region off the Western Antarctic Peninsula. ICES Journal of Marine Science, 70(4), 834-849. doi:10.1093/icesjms/fst088, is available online at: http://icesjms.oxfordjournals.org/content/70/4/834.
The published article is copyrighted by the International Council for the Exploration of the Sea (ICES) and published by Oxford University Press.
Abstract Antarctic krill are a key component of the diet of Adélie penguins inhabiting the Western
Antarctic Peninsula (WAP), yet our understanding of the variability of krill distribution
patterns within nearshore penguin feeding grounds is limited. A recent study of the foraging
patterns of penguins breeding in the northern WAP suggests that tidal phase plays a role in
foraging distance. We used acoustics to examine biomass and aggregation structure of krill in
the penguin foraging grounds off Palmer Station during diurnal and semi-diurnal tides.
Nearshore, integrated krill biomass during diurnal tides was significantly higher than during
semi-diurnal tides. Krill aggregations were also shallower, closer together, and larger in
dimension during diurnal tides. Conversely, krill aggregations had higher volumetric biomass
and abundance during semi-diurnal tides. Further offshore, at the head of the Palmer Deep
canyon, krill aggregations were similar to those observed nearshore during diurnal tides (i.e.,
shallow, close together, and large in dimension). Since krill aggregation structure strongly
influences availability as a potential prey source, we suggest that foraging behavior of Adélie
penguins in this region is strongly linked to the variability in nearshore krill aggregation
structure as well as biomass.
Genre Article
Topic Antarctic krill
Identifier Bernard, K.S., & Steinberg, D.K. (2013). Krill biomass and aggregation structure in relation to tidal cycle in a penguin foraging region off the Western Antarctic Peninsula. ICES Journal of Marine Science, 70(4), 834-849. doi:10.1093/icesjms/fst088

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