The relative importance of biotic and abiotic factors in structuring the littoral zone community in northern Wisconsin lakes will be evaluated. The proposed work builds on 5 years of collaborative research examining the major forces controlling the structure and function of the nearshore community. The approach is comprehensive. It evaluates complex interactions, direct and indirect interactions among predators and their prey, and the cascade hypothesis. They have all been recently applied to the pelagia of lakes, but are largely untested in the structurally- complex environment of the benthic, littoral cummunity. The centerpiece for this effort is a mesocosm experiment in which densities of fish predators of crayfish and crayfish are treatment variables. Treatments in which the fish predators of crayfish are reduced to mimic the impact of winterkill on the top trophic level will be used. The mesocosms represent a scale intermediate between laboratory and whole-lake experiments. The approach is tractable, realistic, and absolutely required to make progress toward understanding those forces structuring the littoral community.
