Copepod foraging in patchy habitats and thin layers using a 2-D individual-based model
Authored by AW Leising
Date Published: 2001
DOI: 10.3354/meps216167
Sponsors:
United States Office of Naval Research (ONR)
United States National Science Foundation (NSF)
Platforms:
Fortran
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
Model code not found
Abstract
Evidence has shown that thin, horizontally extending phytoplankton
layers may be comprised of smaller high-concentration aggregations of
phytoplankton, rather than a homogeneous high-concentration sheet. A 2-D
(horizontal and vertical dimensions) individual-based model of copepod
foraging was developed, in order to examine whether the foraging success
of a copepod would be significantly affected by phytoplankton
patchiness, The foraging rules for the simulated copepods were to
decrease speed and increase turning angle when high food concentrations
are encountered. The underlying distributions of phytoplankton used in
the model were, for the patchy layer scenario, representations of raw
2-D field fluorescence obtained using the Optical Serial Section
Tomography (OSST) device, and for the homogeneous layer scenario, distributions created by simulated vertical sampling of the OSST
distributions with a CTD/Fluorometer. In both the patchy and homogeneous
layer scenarios, the copepods always had higher net foraging efficiency
than randomly behaving controls, suggesting that the simple behavioral
rules adopted are advantageous for copepod-like organisms. Foraging
efficiency was significantly greater for the patchy layer scenarios than
for the homogeneous layer scenarios when patches were small (i.e. one
step length in width) and intense (i.e. near ingestion-saturating
concentrations). Ingestion was up to 30\% higher in the most patchy case
versus its paired homogeneous case, suggesting that the existence of
patchiness is critical to copepod survival, and that sampling scales
should not exceed the step length of a copepod.
Tags
Phytoplankton
plankton
Swimming behavior
Egg-production
Southern-california
Patchiness
Microscale
Acartia-tonsa
Area-restricted search
Food environments