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
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
- How does the circulation field (e.g., upwelling, rapid offshore transport in
filaments) impact the distribution and population success of major CCS
zooplankton species such as Calanus pacificus, Metridia pacifica and Euphausia
- How does the behavior (e.g., vertical migration) of these species interact
with the circulation field ? How does this interaction influence the distribution
and population success of these species?
- How do bioenergetic differences (e.g., in growth effficiency) and
behavioral differences (e.g. in vertical migration excursion) affect the relative
distribution and population success of C. pacificus, M. pacifica and E. pacifica?
The results of this proposal will:
- improve our understanding of how diel vertical migration and circulation
interact to affect the spatial distribution and population success of important
CCS zooplankton species.
- explore how three dominant CCS mesozooplankters, C. pacificus, M.
pacifica, and E. pacifica respond differentially to the physically and
biologically complex environment of the CCS. This is of particular interest
because, although the two copepods are similar in size, they have distinct
behavioral differences that should impact both their spatial distribution and
population success in the CCS. Conversely, the contrast of the euphausiid with
the two copepods will provide insights on how relative differences in both
bioenergetics and behavior impact spatial distribution and population success.