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New Zealand Mud Snail

Potamopyrgus antipodarum (J. E. Gray) -- Mollusca: Prosobranchia: Hydrobiidae

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This pest snail is native to New Zealand from which it has a long history of invading other countries. It was first found in the United Kingdom in 1859, the western Baltic in Europe in 1887, the Mediterranean and eastern Europe were invaded in the 1950's. It has also established in Australia and Japan. In 1987, mud snail was found in the Snake River of Idaho and has since spread through Yellowstone National Park, and is now found in Wyoming, Montana, and Oregon (1994). The Great Lakes were invaded in 1991. Genetic analyses suggest that the source population in the Great Lakes originated from Europe and invaders were introduced into the Great Lakes in ballast water discharged from transoceanic ships that came from Europe. The snail was found in British Columbia Canada in 2007, and the first record of this pest in California was from the Owens River that was officially confirmed in 2000. All western US states, except New Mexico, now have permanent populations of New Zealand mud snail.

The snail shell varies in color from gray and dark brown to light brown. The snail is usually 4-6 mm in length in areas that have been invaded, but snails can grow to almost twice this size, up to 12 mm, in New Zealand where populations are much lower. New Zealand mud snail is a nocturnal grazer that feeds on plant and animal detritus, algae, and diatoms. Invasive populations have an unusual mode of reproduction. New Zealand mud snails can reproduce asexually and female snails are born with developing embryos inside them. Consequently, all populations consist of genetically identical clones. In New Zealand, native mud snail populations consist of sexually reproducing populations (the males make up less than 5% of the populations) and asexually reproducing females. Each snail can produce around 230 offspring a year, and reproduction typically occurs during the spring and summer.

The highest concentration of this snail was in Lake Zurich, Switzerland, where the species colonized the entire lake within seven years of invasion to a density of 800,000 per square meter. These massive populations were not sustained, and a population crash occurred. Thereafter, the snails became less common. A similar event may have occurred in Denmark.

No effective natural enemies of New Zealand mud snail accompanied this invader as it moved about the world. Lack of predators, parasites, and pathogens promotes succesful invasion. Dr. Mark Hoddle noted that in New Zealand, the mud snail is attacked by 11 species of trematode, a type of parasitic flatworm, which sterilizes infected snails. This parasite may be important for regulating mud snail populations in New Zealand thereby preventing them from attaining the high densities that are observed overseas. It is possible that host specific trematodes exist in New Zealand and these may be used to control pest populations of New Zealand mud snail if they can be shown to pose no risk to desirable native snail populations in areas that have been invaded by this pest.

Without eradication procedures, containment is the best defense. Spread is associated with recreational freshwater fishing and wading gear and should be contained. Decontaminate of fishing gear by freezing overnight, or treating with toxic chemicals are recommended by University of California researchers.

REFERENCES:

Kerans, B. L, M. F. Dybdahl, M. M. Gangloff and J. E. Jannot. 2005. Potamopyrgus antipodarum: distribution, density, and effects on native macroinvertebrate assemblages in the Greater Yellowstone ecosystem. Journal of the North American Benthological Society 24 (1): 123–138.

Murtada D. Naser & Mikhail O. Son. 2009. First record of the New Zealand mud snail Potamopyrgus antipodarum (Gray 1843) from Iraq: the start of expansion to Western Asia? Archived 2011-07-21 at the Wayback Machine. Aquatic Invasions, Volume 4 (2): 369-372,

Filippenko, Dmitry P. & Mikhail O. Son. 2008. The New Zealand mud snail Potamopyrgus antipodarum (Gray, 1843) is colonising the artificial lakes of Kaliningrad City, Russia (Baltic Sea Coast). Archived 2011-07-21 at the Wayback Machine. Aquatic Invasions Volume 3 (3): 345-347.

Leovy, Jill. 2010. Hard-to-kill snails infest Santa Monica Mountain watersheds. Los Angeles Times, from the original on 2019-05-23. Retrieved 20 July 2018.

Levri, E. P. 1998. Perceived predation risk, parasitism, and the foraging behavior of a freshwater snail (Potamopyrgus antipodarum). Canadian Journal of Zoology 76 (10): 1878–1884.

Schreiber, E. S. G., A. Glaister, G. P. Quinn & P. S. Lake. 1998. Life history and population dynamics of the exotic snail Potamopyrgus antipodarum (Prosobranchia: Hydrobiidae) in Lake Purrumbete, Victoria, Australia. Marine and Freshwater Research 49 (1): 73–78.

Strzelec, M. 2005. Impact of the introduced Potamopyrgus antipodarum (Gastropods) on the snail fauna in post–industrial ponds in Poland. Biologia (Bratislava) 60 (2): 159–163.