Patterns of shield darter, Percina peltata, distribution in the Eastern Piedmont of Maryland, USA

Abstract

Detailed analyses of habitat associations with rare species are typically constrained by limited sample size and the availability of habitat data. The dense spatial coverage of stream sampling by the Maryland Biological Stream Survey provides ample data to quantitatively examine correlations between habitat and rare species distributions. The shield darter, Percina peltata, has a widespread distribution on the Atlantic Slope of the United States, but is uncommon throughout its range in Maryland. Associations of in situ physical habitat, water chemistry, and alterations in landscape with shield darter presence in the Eastern Piedmont physiographic province in Maryland were examined. Shield darter occurrence was associated with larger sized streams in concordance with the species' known ecology. Shield darter distribution was further associated with stream segments with deep riffle habitats with diverse velocities, low concentrations of chloride and sulfate, low levels of urbanization in upstream catchments, and several pollution intolerant fish species. Although the exact mechanism of the effects is not clear, results indicate that the shield darter is sensitive to urban development and habitat and water quality alteration that typically accompanies urbanization. Shield darter conservation in Maryland necessitates the protection and restoration of minimally urbanized watersheds where they are known to occur. The results from this study indicate that habitat information on rare species may be important in elucidating important habitat associations that are not evident via examination of community level data.