Tuesday, June 5, 2007 - 11:30 AM
126

Identifying diversity among cryptic species: Implications for imperiled snail fauna (Gastropoda: Pleuroceridae) in the increasingly urbanized Cahaba River, Alabama, USA

Lori R. Tolley-Jordan1, Alexander D. Huryn1, and Arthur E. Bogan2. (1) Department of Biological Sciences, The University of Alabama, Box 870206, Tuscaloosa, AL 35487, (2) North Carolina State Museum of Natural Sciences, Raleigh, NC 27607

Loss of gastropod diversity from the Cahaba River drainage, Alabama, is of particular concern to conservation biologists because it is a global hot-spot for pleurocerid diversity.  However, identification of these species is difficult due to extreme shell variability and lack of taxonomic keys. We categorized variability of pleurocerids by creating a catalogue of 105 nominal species (morphotypes) that were historically known to occur in the Cahaba River and are listed as synonyms of the 20 currently recognized species. 28 morphotypes were recovered from a survey of 100 sites along the river.  Using the morphotypes to show changes in distributions of the 20 recognized species from a 1993 survey of the same 100 sampling sites showed populations of 4 species were locally extirpated.  10 sites had changes in species richness between the two surveys. Seven sites lost 1-2 species and 3 sites gained 1 species.  Remote sensing data of the basin during 1992 and 2003 showed a 4% increase in urban cover. Decreased richness occurred only in catchments with increased urban land cover. These results suggest that pleurocerid snails are sensitive to altered stream conditions caused from conversion of catchments from forest to urban cover.