9508981 STRAYER Response and compensation to a bivalve invasion by an aquatic ecosystem Thousands of species of plants and animals from around the world have become established in North America. In some cases, these exotic species seem to have had little or no effect on native ecosystems, whereas in other cases native species and ecosystems have been deeply and irreversibly affected. We are studying the effects of the zebra mussel, a European pest, on the Hudson River ecosystem. The zebra mussel arrived in the Hudson in about 1990, and is now by far the most abundant animal in the river. It has dramatically reduced densities of phytoplankton and small zooplankton (the small plants and animals at the base of the food chain) over a 150-km reach of the river, but other components of the ecosystem have been affected much less severely. We will use long-term field studies, computer models, and small-scale experiments to examine how the various parts of the Hudson River ecosystem respond to the zebra mussel population. By studying the details of the zebra mussel invasion in the Hudson, we hope to identify the general features that control the sensitivity of native ecosystems to invasions of exotic species. ??
