Miller, A. J., E. Di Lorenzo, D. J. Neilson, H.-J. Kim,
A. Capotondi, M. A. Alexander, S. J. Bograd, F. B. Schwing,
R. Mendelssohn, K. Hedstrom and D. L. Musgrave, 2005:
Interdecadal changes in mesoscale eddy variance in the Gulf of Alaska circulation: Possible implications for the Steller sea lion decline
Atmosphere-Ocean, 43, 231-240.
Abstract.
A distinct change in the ocean circulation of the Gulf of Alaska
after the 1976-77 climate shift is studied in an
eddy-permitting primitive equation model forced by observed wind stresses
from 1951-1999. When the Aleutian Low strengthens after 1976-77,
strong changes occur in the mean velocity of the Alaskan
Stream and in its associated mesoscale eddy field. In contrast,
the Alaska Current and the eddy flows in the eastern Gulf
remain relatively unchanged after the shift. Since mesoscale eddies provide a
possible mechanism for transporting nutrient-rich open-ocean waters
to the productive shelf region, the flow of energy through the
food web may have been altered by this physical oceanographic change.
This climate-driven mechanism, which has a characteristic
east-west spatial asymmetry, may potentially help to explain
changes in forage fish quality in diet diversity
of Steller sea lions whose populations have declined precipitously since the
mid-1970's in the western Gulf while remaining stable in the eastern Gulf.
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