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.
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
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
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
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
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.
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