As this year's president of the AMS, I've become involved with a USDA initiative to identify mollusks (of all sorts) that have the potential to become pests*. Although most of the critters falling into this category are land snails and slugs, occasionally freshwater gastropods receive some attention.
The following news item was called to my attention by Jim Smith, a scientist at in the USDA's Animal and Plant Health Inspection Service whom I've recently had the pleasure to work with. It comes from a web site that's new to me - NAPPO, the North American Plant Protection Organization. http://www.pestalert.org/pestnews.cfm
Subject: Mollusk from New Zealand expands range in US
Date posted: 04/23/02
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 out compete algae-feeding aquatic insects, the main food source of trout.The NAPPO web site also has a nice write-up on Pomacea canaliculata in the "Pest Alert" section, with a 14-page data sheet. Go to their website and submit "Mollusks" on the Pest Alert page, if you're curious.
We're anticipating several talks on the subject of molluscan pests at the Charleston meeting this August, including contributions by Jim Smith and by Rob Cowie, the chair of the AMS Committee spearheading this effort. Registration for that meeting will continue until June 30.
This paper was ultimately published in 2009:
Cowie, R. H., R. T. Dillon, D. G. Robinson and J. W. Smith (2009) Alien non-marine snails and slugs of priority quarantine importance in the United States: A preliminary risk assessment. American Malacological Bulletin. 27: 113-132. [PDF]