Potamopyrgus antipodarum in United States

CURRENT INVASION STATUS

Introduction to North America:

The first reported finding of this mud snail in North America was in the Snake River, Idaho in 1987.  Two years later the snail had spread from strictly algae covered and rocky substrates to become the dominant mollusk in all aquatic habitats of the Middle Snake River.  Since then, the spread of this species has continued at a remarkable pace: it spread to the Great Lakes, and then over the continental divides into the Colorado River and the Madison and Yellowstone basins in the Greater Yellowstone Ecosystem. The snails were first discovered in California in 2000 in the Owens River.  The means of introduction to the United States is unknown, but may have occurred with the transfer of fish eggs and live game fish, or in ballast water. All of the western populations of the New Zealand mud snail are the same clone.

NZMS clones
Distribution of NZMS snail genotypes in introduced range.
Modified from Fromme & Dybdahl 2006, J Evol Biol.

Majority NZMS in the Western U.S. are descendents of one clone from the North Island of New Zealand or Australia. These monoclonal populations, which possess no genetic diversity, seem to exhibit a phenotypic plasticity which enhances their capacity to spread across habitats (Dybdahl 2003).

The second known clone of  P. antipodarum in the US was most likely introduced to the Great Lakes in ships from Europe, where there are nonindigenous populations (Zaranko et al. 1997; Leppäkoski & Olenin 2000; Levri et al. 2007).  They may also have been introduced in the water of live gamefish shipped from infested waters to western rivers in the United States.

NZMS

Potamopyrgus antipodarum- (photo by Danuta Bennett)

 

Migration:

The pattern of NZMS invasion involves geographic jumps, which supports the theory of introduction to new sites from various vectors and not under its own volition since we don’t observe a smooth and steady invasion front. The spread of NZMS into new systems is believed to be mostly caused by humans, with the most common dispersal methods being hatchery transplants, contaminated fishing equipment, boats, and trailers (Richards 2002). Other possible vectors of introduction could include wading anglers moving between sites, rafters and kayakers floating between river access points, fishery biologists sampling various sites, etc. Additionally, some authors reported spread by waterfowl (Lassen 1978 in Richards 2002), fish and discarded aquarium plants and pets as being other possible vectors.

 

 

Since introduction, both active and passive transport methods have contributed to its spread. New Zealand mudsnail have been shown to spread independently upstream through locomotion. Passive spread by birds, through the alimentary canal of fish is also documented (Haynes et al. 1985; Richards et al. 2004. P. antipodarum can survive passage through the guts of fish and birds and may be transported by these animals (Aamio and Bornsdorff 1997). It can also float by itself or on mats of Cladophora spp., and move 60 m upstream in 3 months through positive rheotactic behavior (Zaranko et al. 1997). It can respond to chemical stimuli in the water, including the odor of predatory fish, which causes it to migrate to the undersides of rocks to avoid predation (Levri 1998).Findings from a study conducted on the eastern Snake River of Idaho suggest that NZMS mostly spread through vegetation and edges of the faster-flowing waters and then move into new habitats, particularly vegetated ones (Richards, et al. 2001). NZMS was also observed to be more likely to detach from substrate due to flow or disturbance then was a native snail (Taylorconcha serpenticola) (Richards, et al. 2001).

The snails can be transported on boats and other watercraft, or on fishing equipment such as waders and nets. Hunters and other outdoor enthusiasts who spend time in the water may potentially move snails from one body of water to another without knowing it.
NZMS is actually very fast snail (estimated substrate cruising speed is > 1 meter/hour (Richards personal observation).

For current locations in USA visit U.S. Geological Survey, New Zealand Mud Snail distribution ( or click on the map below)

Benson, A. J. 2010. New Zealand Mud Snail sightings distribution. Retrieved [May 2010] from newzealandmudsnaildistribution.aspx

REPORT NEW ZELAND MUD SNAIL

Use this form to report new location of New Zealand Mud Snail. Your information will help in prioritizing ongoing research on this invasive species and it will also help to protect native habitats from negative impact of these snails.

  


 

 

 

 

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