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Landscape dynamics and resulting species interactions: the cod-capelin system in the southeastern Bering Sea

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Title Landscape dynamics and resulting species interactions: the cod-capelin system in the southeastern Bering Sea
Names Ciannelli, Lorenzo (creator)
Bailey, Kevin Mclean (creator)
Date Issued 2005-04-28 (iso8601)
Abstract Capelin are a major component of cod diet in many ecosystems of the North Atlantic. In
the Bering Sea, however, the percentage of capelin found in Pacific cod stomachs is negligible. We
hypothesize that the landscape (or ‘seascape’) features of hydrography and bathymetry of the Bering
Sea impose a constraint on the distribution of cod and capelin that contributes to their spatial segregation
and ultimately, to their uniquely weak trophic link. We analyzed a long-term data collection
(1972 to 2001) on Pacific cod and capelin catches and feeding interactions, and developed a new
metric to quantify the spatially explicit overlap between a predator and a prey. Our analysis indicates
that cod and capelin distributions respond to the thermal conditions of the Bering Sea. Typically, a
frigid water mass is present on the middle portion of the shelf, and cod distribution is confined to the
southern side of the cold pool, while capelin is confined to the north. However, in warm years the
middle shelf is penetrated by thermal gateways (between 1 and 6°C), allowing cod to invade the
capelin habitat. In this situation, when cod and capelin overlap, cod feed heavily on capelin. The
annual index of cod and capelin overlap is correlated with the Pacific Decadal Oscillation (PDO)
index, a climate indicator of the North Pacific. The width of the thermal gateways in the middle shelf
is also correlated with the PDO. These results point to a direct causal link, from climate and thermal
conditions of the Bering Sea shelf, to cod and capelin distribution, and ultimately to their overlap and
trophic interactions.
Genre Article
Topic Pacific cod
Identifier Ciannelli, L., & Bailey, K. M. (2005, April 28). Landscape dynamics and resulting species interactions: the cod-capelin system in the southeastern Bering Sea. Marine ecology progress series, 291, 227-236.

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