Linked Biophysical Modeling in the California Current System: The Influence of Circulation and Behavior on Prominent Mesozooplankton Species

T. Powell [Univ. of California, Berkeley] and D. Haidvogel [Rutgers Univ.]

Eastern Boundary Current Systems, such as the California Current System (CCS), owe their high phytoplankton productivities to circulation patterns that bring nutrient-rich deep waters to the surface. Further, the spatial patterns of high primary and secondary productivity appear to be closely linked to mesoscale physical structures (e.g. filaments, jets, and eddies) in the CCS. We hypothesize that both spatial distribution and demographic processes (e.g. growth, fecundity, mortality) of calanoid copepods (e.g. Calanus pacificus and Metridia pacifica) and euphausiids (e.g. Euphausia pacifica), are influenced by circulation patterns within the CCS. We also hypothesize that the vertical migration behavior of these zooplankton influences their spatial distribution and demographic processes through the interaction between vertical migration and the circulation field. Moreover, the bioenergetic and behavioral differences between species are hypothesized to influence differential population successes and spatial distributions.

To address these hypotheses, we will construct a series of linked physical-biological models of the CCS. We propose to use an individual-based bioenergetics model to simulate CCS zooplankton behavior and phenology, to simulate the CCS circulation field with SPEM5. 1, and to link the two via simulated Lagrangian drifters.

Using the linked models we intend to address the following questions:

In general, the models developed in this project represent a major advance in incorporating detailed zooplankton biology and ecology into realistic, three-dimensional circulation models. The method we have chosen, coupling a bioenergetics individual-based model, that includes behavior, with a detailed physical circulation model is generally applicable to populations in other ocean ecosystems.

The results of this proposal will: