9311304 Herrnkind The purpose of this Doctoral Dissertation Improvement Grant is to investigate a non-trophic indirect interaction between a predatory marine gastropod and an assemblage of benthic fish that shelter and lay eggs in the shells of the gastropod's main prey, the pen shell Atrina. As a major source of Atrina mortality, the gastropod should influence shelter availability, and thus indirectly affect species occupying the shells. Since the fish also use the shells as a site for reproduction, the gastropod predator may influence both population distribution and egg production. This study will assess the relationship between Atrina and each fish species by experimentally varying pen shell mortality rates, and separately measuring factors that should influence Atrina mortality, namely abundance and individual feeding rates of the gastropod predator. %%% This information will allow a quantitative evaluation of the interaction between the predator and the fish occupants in terms of local abundance and reproductive output. Understanding how interspecific interactions influence populations and communities has been a major goal of ecological research. Direct predator-prey and competitive interactions are widely studied. Indirect interactions have received less attention, but evidence for their importance is growing. This study will contribute important information towards a better understanding of the role of indirect interactions in the abundance and distribution of aquatic organisms. ***
