Distribution and Habitat Characteristics of a Freshwater Gastropod, Pleurocera Proxima, in Eastern Pennsylvania

Pleurocera proxima is a small, freshwater gastropod that has been recently discovered in four headwater tributaries in the Christina River watershed. The species was previously known only as far north as Virginia, so nothing is known about the species in Pennsylvania or Delaware. The purpose of this study was to determine if the species existed in additional locations in this region, and to assess the habitat where it is found. Fieldwork was conducted in Winter 2012 in the Red Clay Creek, White Clay Creek, and Brandywine Creek subwatersheds of the Christina River basin. In addition to the four streams where P. proxima was already known, 102 new streams were surveyed in this field season for presence of the species. Water chemistry and surrounding land use data were collected at all sites, and substrate characteristics and physical stream data were collected at sites with P. proxima. Only four of the 102 new sites had P. proxima. These data suggest the species is very rare in the region, and mostly populates small, headwater streams in areas with low developed land cover and high forest cover. The streams where P. proxima is found show lower levels of conductivity and salinity than other streams, but it is apparent further research is needed to identify the exact habitat conditions that predict P. proxima presence and density.