Meeting Abstract

29.6  Friday, Jan. 4  Competition and Biogeography of Freshwater Mussels LEVINE, TD; Miami University levinetd@muohio.edu

Unionid mussels constitute a highly threatened taxon, which achieve their greatest diversity in North America. To effectively conserve freshwater mussels it is necessary to understand their basic ecology. Recent theoretical models have demonstrated that mussels may interact competitively during their larval phase (glochidia), which includes an obligate attachment to fish hosts. Fish hosts exposed to glochidia develop immunological reactions that prevent or reduce the success of subsequent infestations by glochidia of related mussel species. Therefore, it is possible that the distribution of freshwater mussels may be limited by interspecific competition for host fish. I combined data from literature values on resistance of host fishes to reinfestation and a host-use database to develop a simple host exploitation index. I applied this index to distributional data from national databases of presence/absence and predicted distributions to determine which hosts are locally most heavily exploited. I also tested whether hosts were evenly exploited, indicating that there may be a saturation of host use within a drainage. I will discuss the potential competition within the unionid fauna across several south-central and midwestern drainages. This preliminary analysis highlights areas where studies on competition among mussel species would be most fruitful. Information on interspecific competition in mussels is valuable in reconstructing ranges and ecological interactions of historical communities. A host exploitation index, such as the one described here, could prevent incompatibilities among mussel species of conservation concern in culture and reintroduction efforts.