The invasive New Zealand mud snail potamopyrgus antipodarum (J.E. Gray, 1843) in central Pennsylvania

The highly invasive New Zealand mud snail (Potamopyrgus antipodarum) has established a relatively recent population in central Pennsylvania. The purposes of the work described here were to determine the extent of the invasion, the rate of spread, and the relationship between the abundance of the snail and calcium ion concentration, pH, and conductivity. In two independent sampling efforts, we sampled Spring Creek in Centre County, Pennsylvania, at various times from 2014 to 2018. We also sampled tributaries of the stream as well as the larger watershed of Bald Eagle Creek. In addition, we established sites to monitor other streams that are likely to be frequented by recreational water users (a known snail dispersal agent). We found that compared to the geographic distribution in 2014, the snail increased its geographic range, and snail abundance increased at most locations. We also found evidence of expansion out of the Spring Creek watershed into the larger Bald Eagle Creek watershed at two locations in 2018. Snail abundance was positively related to pH and conductivity in 2017. We recommend that streams in central Pennsylvania be routinely monitored for the presence of this species, especially those regularly visited by recreational water users and that have chemical characteristics favorable to the NZMS.