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Advection and starvation cause krill ( Euphausia pacifica ) decreases in 2005 Northern California coastal populations: Implications from a model study
Author(s) -
Dorman Jeffrey G.,
Powell Thomas M.,
Sydeman William J.,
Bograd Steven J.
Publication year - 2011
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl046245
Subject(s) - krill , euphausia , population , oceanography , seabird , advection , antarctic krill , trophic level , predation , plankton , environmental science , biology , starvation , ecology , geology , physics , demography , thermodynamics , endocrinology , sociology
A decrease in krill abundance during 2005 in regions of the California Current has been hypothesized to have had immediate (seabird) and long‐term (salmon) negative impacts on upper trophic level predators. We use a suite of coupled models to examine the population biology and spatial and temporal distribution of the krill species Euphausia pacifica during the winter/spring of 2001, a “normal” year, and 2005, an “anomalous” year, to determine if this hypothesis is supported mechanistically. Ocean conditions were simulated using the Regional Ocean Modeling System (ROMS), which forced an individual‐based model parameterized to simulate the population biology of E. pacifica . Poleward transport during winter 2005 advected particles north of Cape Mendocino, away from seabirds and salmon feeding in the Gulf of the Farallons region. Few of the particles that were advected north in 2005 returned to their region of release throughout the model run time (200 days). Moreover, the “condition” of those particles remaining within the domain was poor in 2005, with greater mortality from starvation and a decreased mean particle weight. Our results indicate that both physical processes (anomalous northern advection) and biological processes (greater starvation and less weight per individual) contributed to reduced krill availability to predators in the northern California region during 2005, and that the productivity and survival of seabirds and salmonids is dependent on krill during critical life history stages.