US-Sweden Cooperative Research: Complex Interaction Among Fish Predators in Littoral Benthic Communities

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This award will support collaborative research in aquatic ecosystems between Dr. Roy Stein, Ohio State University and Dr. Christer Bronmark, University of Lund, Sweden. The objective of the proposed project is an examination and evaluation of interactions among fish predators which affect the >structurally.complex environment of natural ponds. Dr. Stein is currently carrying out a large scale experiment in the northern Wisconsin lakes to study the role of predators in structuring nearshore communities. Using laboratory experiments, lake surveys and a large.scale inshore mesocosm experiment (where portions of the nearshore are enclosed by a curtain), the Wisconsin research team is exploring how biotic and abiotic factors influence all facets of the littoral community, including predatory fishes, crayfish, snails, periphyton and macrophytes. Because of the abundance of small ponds near Lund, Sweden with piscivorous and benthivorous fishes, snails, periphyton and macrophytes, whole.system manipulations of predators can be done without resorting to the use of large enclosures. In contrast to the Wisconsin work, the work proposed for Sweden, which includes a pond survey (to qualify field patterns) and predator manipulations (where northern pike and tench densities are treatment variables), will evaluate in a more extensive fashion how fish predators interact to directly and indirectly influence snails, periphyton, and macrophytes in natural ponds. This work will directly test the trophic cascade hypothesis, recently applied to the pelagia of lakes, but largely untested in the structurally.complex environment of the benthic, littoral community. The project will benefit from the complementary expertise of the two investigators. Dr. Bronmark has extensive experience with interactions among snails, periphyton and macrophytes. Dr. Stein's expertise lies in quantifying the behavioral interactions between fish predators and their prey and how these interactions might be mediated by habitat structure.