Advection and starvation cause krill (Euphausia pacifica) decreases in 2005 Northern California coastal populations: Implications from a model study

Authored by William J Sydeman, Jeffrey G Dorman, Thomas M Powell, Steven J Bograd

Date Published: 2011

DOI: 10.1029/2010gl046245

Sponsors: United States National Aeronautics and Space Administration (NASA) United States National Science Foundation (NSF) California Energy Commission

Platforms: No platforms listed

Model Documentation: Other Narrative

Model Code URLs: Model code not found

Abstract

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. Citation: Dorman, J. G., T. M. Powell, W. J. Sydeman, and S. J. Bograd (2011), Advection and starvation cause krill (Euphausia pacifica) decreases in 2005 Northern California coastal populations: Implications from a model study, Geophys. Res. Lett., 38, L04605, doi:10.1029/2010GL046245.

Tags

Climate Dynamics Productivity Prey Variability Temperature Biology Wind Current system Ptychoramphus-aleuticus