Potamopyrgus antipodarum

Phylum: Mollusca
Class: Gastropoda
Order: Mesogastropoda
Species name: Potamopyrgus antipodarum (Gray, 1843)
Synonyms: Hydrobia jenkinsi E.A. Smith, 1889, Potamopyrgus jenkinsi (E.A. Smith, 1889).
Common name: Jenkin's spire shell
 
Date of introduction and origin
Potamopyrgus antipodarum was probably introduced as early as 1859 (D. Heppell pers. comm.). It was first recognised in Europe (as Hydrobia jenkinsi) by Smith (1889) from Plumstead, Beeton and Erith, in the Thames estuary, England. Earlier introductions may not, however, have become established, and it is considered that the Thames introduction is the source of the population in Britain. This species originates in New Zealand from whence it was introduced into Australia. It was introduced to Britain from southern Australia or Tasmania (Ponder 1988).
 
Method of introduction
It was introduced in drinking water barrels in ships from Australia (Ponder 1988). The snails were probably liberated while washing or filling water barrels or tanks and, because they can survive in brackish water, they could probably survive liberation into estuarine areas such as the River Thames.
 
Reasons for success
This species can reproduce rapidly parthenogenically. It thrives in freshwater and has become the most common freshwater gastropod in Britain.
 
Rate of spread and methods involved
Its rate of spread around the coast was moderate, however, once it started colonising freshwater habitats around 1904 (Castell 1962), it spread very rapidly. Firstly along major rivers and canals, then filling in the smaller streams and ditches etc. until, by 1920, it was very widespread in Britain.
 
Distribution
It is found in saline lagoon and brackish water ditches around Britain. Its distribution in freshwater extends from Shetland to the Isles of Scilly although in much of mainland Scotland it is confined to coastal areas. It had reached the European mainland (probably from Great Britain) by 1900 and is now widespread there (Wallace 1985).
 
Factors likely to influence spread and distribution
Its success in freshwater has led to its spread along water courses thus greatly extending its range.
 
Effects on the environment
Unknown other than it eats water cress but that is not a concern as this snail is so small.
 
Effects on commercial interests
In the early 1900s it was reported to be choking up London's fresh water supply (Castell 1962), however, the use of filters overcame this problem.
 
Control methods used and effectiveness
None used.
 
Beneficial effects
None known.
 
Comments
This species is known from southern Australia and Tasmania. Ponder (1988) gives evidence to support the hypothesis that it is an introduction there from New Zealand, by European man or birds (the genus has diversified in New Zealand, but there is no evidence of this in Australia). Earliest known dates for Australian introductions are: Hobart area, Tasmania - 1872; Melbourne area, Victoria - 1895; Adelaide area, South Australia - 1926; Sydney area, New South Wales - 1963.
 
It was noted in 1889 that it was found in Tasmania "in the River Tamar and other places within the influence of salt water".
 
In the Sydney area Potamopyrgus has bred in freshwater tanks and reservoirs and has even been distributed through water pipes to emerge from domestic taps. In South Australia it has blocked water pipes and meters. It was probably first introduced to Tasmania by way of drinking water supplies on ships and probably entered Europe at about the same time in the same way.
 
The spread of Potamopyrgus further north into New South Wales may possibly be limited by high water temperatures, as it has been shown that New Zealand and European populations cannot tolerate a water temperature of more than about 28·C.
 
References
Macan, T.T. 1977. A key to British fresh- and brackish- gastropods. 4th edition Freshwater Biological Association Scientific Publication No. 13
 
Ponder, W.F., 1988. Potamopyrgus antipodarum: a molluscan coloniser of Europe and Australia. Journal of Molluscan Studies, 54: 271-285.
 
Smith, E.A., 1889. Notes on British Hydrobidae with a description of a supposed new species. Journal of Conchology, 6, 142-145.
 
Wallace, C. 1985. On the distribution of the sexes of Potamopyrgus jenkinsi (Smith). Journal of Molluscan Studies, 51: 290-296.
 
Acknowledgements (contributions from questionnaire)
Dr David Heppell, Curator of Mollusca, National Museums of Scotland.