The Role of Structural Complexity in Predator-Prey Interactions

EPA Grant Number: U915339
Title: The Role of Structural Complexity in Predator-Prey Interactions
Investigators: Lewis, David B.
Institution: University of Wisconsin - Madison
EPA Project Officer: Broadway, Virginia
Project Period: September 1, 1998 through September 1, 2002
Project Amount: $58,068
RFA: STAR Graduate Fellowships (1998) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems


The objective of this research project is to determine whether the reduction of structural complexity alters predator-prey interactions and, in turn, species diversity in benthic habitats. To assess the generality of these patterns, the surprisingly similar snail-decapod interactions in the salt marshes of North Carolina, and the temperate lakes of Wisconsin serve as model systems.


This research benefits from complementing field surveys and laboratory experiments with simulation modeling. In each system, field surveys compare prey and predator densities between areas with high- and low-refuge habitat. In salt marshes, this entails spanning gradients of marsh grass height and tidal elevation; in lakes, animals are sampled in various substrates including macrophyte refugia. Laboratory experiments investigate predation as a possible mechanism underlying field distribution patterns. One set of experiments examines the behavioral, habitat use, and growth rate response of snails to chemical cues produced by predators. Another set manipulates the availability of habitat and measures snail mortality to decapods. Field experiments will test whether the ultimate control of plant refuge habitat (nonnative herbivores) is indirectly responsible for mediating snail-decapod interactions. This will be tested with paired exclosure-control experiments, and comparisons of snail and predator response will be made between treatments of recovering and grazed plants. In Wisconsin, the response of snails to crayfish may represent an "out of the frying pan, into the fire" phenomenon, as depressed growth rates and habitat shifts may expose snails to increased predation from fish. A simulation model, parameterized with laboratory experiments, is being developed to investigate the mortality consequences for snails of responding to crayfish.

Supplemental Keywords:

fellowship, macrophyte refugia, snail, decapod, salt marshes, snails, crayfish, habitat, herbivores, predator, prey, plant refuge habitat., Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Habitat, Ecology and Ecosystems, habitat dynamics, habitat species co-occurrence, species interaction, benthic habitat, animal responses, diversity of species, conservation biology, habitat population structure, predation