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Subject: Mollusk from New Zealand expands range in US
Date posted: April 23, 2002
Source: US Geological Survey
The New Zealand mudsnail, Potamopyrgus antipodarum, first recorded from North America in Idaho's Snake River watershed in 1987, has added Arizona to its US distribution. Through the 1990's, the mudsnail spread to the waters of Montana, Wyoming, and California, including public lands such as Yellowstone National Park. In the eastern US, P. antipodarum is found in Lake Ontario, where a population was discovered in 1991. While widely distributed through Australia, Asia, and Europe, this species, as it name suggests, is native to freshwater lakes and streams of New Zealand. The snail is capable of rapid population growth, reproducing parthenogenically, and in Yellowstone, localized infestations can reach a density of 28,000 individuals per square foot. In the United Kingdom, P. antipodarum is reported to eat watercress; however, the main concern in the US is that the mudsnail will outcompete algae-feeding aquatic insects, the main food source of trout.