GLOBEC Collaborative Research: Effects of Seasonal and Interannual Variability on Zooplankton Populations in the California Current System using Coupled Biophysical Models
T. M. Powell, H. P. Batchelder [University of California at Berkeley], D. B. Haidvogel [Rutgers University]

The California Current System (CCS) owes its high phytoplankton productivity to wind-driven circulation patterns that bring nutrient-rich waters to the surface. These high rates of primary productivity are translated via high zooplankton secondary productivity, into high biomass of epipelagic fishes such as anchovies, hake, and salmon. Further, spatial patterns of high primary and secondary productivity are heterogeneous and appear to be closely linked to mesoscale physical structures (e.g., filaments, jets, and eddies). Using a series of linked physical/ecosystem/zooplankton models, we propose to study on seasonal and interannual time-scales the complex interaction of physical and biological processes (diel vertical migration and growth efficiency) in the CCS. We will emphasize major calanoid copepods (e.g., Calanus pacificus and Metridia pacifica) and euphausiid species (e.g., Euphausia pacifica and Thysanoessa spinifera) that represent critical linkages between primary production and salmon populations. In addition, we propose to further illuminate the roles of these processes through comparative studies with other ecosystems located within both similar and dissimilar dynamical environments.

Our goal is to address the following questions:

• How does the circulation field impact the distribution and population success of major CCS zooplankton species such as C. pacificus, M. pacifica, E. pacifica, and T. spinifera?
• How do the behavioral and bioenergetic differences of these species interact with the circulation field, prey distribution and temperature to influence their relative population success?
• How does the interannual variability of the local environment (e.g., from large-scale atmospheric or oceanic fluctuations) modify these distributions and relative success of major CCS zooplankton species?
• How do physical and biological aspects of the CC/Zooplankton System compare to other well-studied ecosystems including those of particular interest to GLOBEC (e.g., Georges Bank, Gulf of Alaska, and Southern Ocean). <./ul>

  The results of this proposal will include the developed ecosystem and zooplankton models, applied within regional and basin-scale circulation models. The coupled systems will be analyzed under seasonal and realistic surface forcing closely tied to CCS process studies. Furthermore, we will begin a comparative synthesis of physical and biological coupling within this and other well-studied GLOBEC ecosystems.

  Year One Work

  During the first year of funding, we plan to implement a ca. 5 km resolution oceanic general circulation model over the Oregon/Northern California region and evaluate its dynamics over an annual cycle. In addition, we will analyze a NPZD ecosystem model and its response in a two-dimensional physical model under idealized forcing conditions. Finally, we will include reproduction and mortality in a zooplankton individual-based model and evaluate the resulting interactions with the same two-dimensional physical model.

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  This page was last updated on March 15, 2007.
  
  Maintained by:
  Hal Batchelder
  College of Oceanic and Atmospheric Sciences
  Oregon State University
  Corvallis, OR 97331-5503
  phone: 541-737-4500; FAX 541-737-2064