NSF Org OPP
Latest Amendment Date September 1, 1995
Award Number 9523748
Award Instr. Continuing Grant
Prgm Manager Polly A. Penhale
OPP OFFICE OF POLAR PROGRAMS
O/D OFFICE OF THE DIRECTOR
Start Date November 1, 1995
Expires October 31, 1997 (Estimated)
Expected Total Amt. $148,061 (Estimated)
Investigator Mark E Huntley mhuntley@soest.hawaii.edu
Meng Zhou
Sponsor U of Cal SD Scripps Inst
La Jolla, CA 92093
NSF Program 5111 ANTARCTIC BIOLOGY & MEDICINE
Fld Science 43 Biological Oceanography
Fld Applictn 0204000 Oceanography
0311000 Polar Programs-Related
Abstract
9523748 Huntley Patchiness of zooplankton and micronekton is a feature of
central importance in marine ecosystems. In the Southern Ocean, aggregations
of krill (Euphausia superba) are of particular interest. The distribution and
dynamics of such aggregations are critical to determining the transformation
of organic matter (e.g. carbon flux) and the fate of populations in the
sea. These phenomena are especially important in the mesoscale and sub-
mesoscale domains, where patchiness is most strongly expressed. If the means
to predict patch dynamics is lacking, then so is the means to adequately
predict carbon flux and population dynamics at these scales. Traditional
models of zooplankton patch dynamics generally treat animals as Lagrangian
particles whose aggregations are determined solely by processes of advection
and diffusion. This approach ignores behavior induced by biotic and abiotic
forces and manifested as purposeful motion - motion that clearly is not
governed by advection and diffusion. Attempts to acknowledge behavior in
models of plankton motility have been successful at the level of the
individual animal, but even the most powerful computers cannot run
individual-based models to predict aggregation dynamics of n
individuals. This proposal takes a new approach to modeling aggregation
dynamics, based on "bio-continuum" theory, and provides for model
verification against benchmark field data. Rather than relying on
traditional advection-diffusion equations, which ignore behavior, the
bio-continuum theory recognizes behavioral forces in the context of
statistical mechanics. Model output provides information on animal
behaviors, manifest as swimming velocities, that are absent from other
models of patch dynamics. All key model variables are measurable using
common sampling techniques, such as acoustic Doppler and multiple net
systems. The proposed research consists of studying both the internal and
external forces that act on aggregations of Euphausia superba. First, the
internal forces of autocoherence (that act between animals to maintain patch
integrity) will be measured in krill aggregations observed in the Gerlache
Strait region in 1992. Our database consists of more than 20 such
aggregations observed by ADCP and MOCNESS. Second, the effect of external
physical forcing on krill aggregations will be studied by embedding krill
swarms of typical scales in numerically modeled flow regimes that are typical
of the Gerlache Strait region (Zhou and Niiler 1995), by combining the
Princeton circulation model (e.g. Blumberg and Mellor 1987) with our
aggregation model. This research provides a novel, dynamic theory of animal
aggregations in the sea. A study of the fundamental theory, coupled with
model realizations that can be compared to observed aggregations of
Euphausia superba, may lead to more realistic predictions of krill patch
dynamics in the Southern Ocean. Such predictions are critical to more
accurate measurements of carbon flux and the population dynamics of krill.