Range Expansion of the Invasive New Zealand Mudsnail (Potamopyrgus antipodarum) in the Susquehanna and Delaware River Basins of Pennsylvania

Abstract

Abstract New Zealand mudsnails (Potamopyrgus antipodarum; hereafter NZMs) are small (≤6 mm in length) freshwater snails that are considered an invasive species in North America. Invasions of NZMs are typified by high densities of snails, which may cause trophic disruptions by displacing native benthic macroinvertebrates. Although NZMs are previously known from several locations in Pennsylvania, we surveyed 24 streams in the lower/middle Susquehanna River basin and Delaware River basin that were not previously evaluated for the presence of NZMs. We detected three range expansions within the Susquehanna basin and 12 range expansions of NZMs in the Delaware River basin, suggesting that NZMs are more widespread in these regions than was previously known. As many of these locations are popular trout waters, introductions are likely the result of spread on fishing gear.