> Habitat & Distribution

Native to New Zealand, invasive populations of Potamopyrgus antipodarum first appeared in Europe in the mid-nineteenth century and in North America in the late-1980s (Ponder 1988, Zaranko et al. 1997).  At least two separate introductions seem to have occurred into US waters – a western population first discovered in the Snake River of Idaho (now spread as far as California and Arizona) and an eastern population first discovered in Lake Ontario, spreading through the Great Lakes (Emblidge Fromme & Dybdahl 2006,  Dybdahl & Drown 2011) into Atlantic drainages.  It has been suggested that the western population comprises two primary clones and the eastern population a third (Bilka & Levri 2013, Levri et al 2014) although this is not well-documented.  A great number of clones seem to have evolved subsequent to the western introduction (Hershler, Liu & Clark 2010) in any case.

The first record of Potamopyrgus in any US Atlantic drainage seems to be a 2010 macrobenthic sample taken by the PA-DEP from Spring Creek, a tributary of the Susquehanna River in Centre County, PA.  By 2017 the snail spread about 50 km south, to the Gunpowder River just north of Baltimore, and shortly thereafter was discovered in the Musconetcong River of northwestern New Jersey (essays below).  The most recent survey of Hartzell & Shank (2024) reported Potamopyrgus in 71 of 443 sites surveyed throughout Pennsylvania, including several tributaries of the Susquehanna and Delaware Rivers, and Falling Branch (of Conococheague Creek), a tributary of the Potomac.  The 2023 distribution map downloadable from the link below is already out of date.

Potamopyrgus populations seem to reach their highest concentrations in the shallows and backwaters of organically-rich rivers and streams.  They are often associated with recreational trout fisheries, spread either through bait bucket transport, or by gut passage in the fish themselves (Bondeson & Kaiser 1949).  See my essay of 19Nov13 from the link below for additional information regarding the Spring Creek introduction.

The habitat tolerance of Potamopyrgus is remarkably broad, however.  They seem to demonstrate little substrate specificity (Heywood & Edwards 1962). Levri and colleagues (2008) reported populations extending to a depth of 45 m in Lake Ontario.  Populations are not uncommon in the brackish waters of New Zealand and Europe, up to 27 ppt salinity (Todd 1964, Winterbourn 1970a, LeClair & Cheng 2011).  Their tolerance at the softwater, low calcium end of the scale is not especially impressive, however (Herbst et al. 2008).  Hartzell & Shank (2024) documented significant associations between the distribution of Potamopyrgus in Pennsylvania, alkalinity, hardness, calcium, specific conductance, and overall nutrients. Resistance to drying has been studied by Poznanska and colleageus (2015), and freezing by Cheng & LeClair (2011).

Potamopyrgus antipodarum is pseudo-rare in our 17-state study area, FWGNA incidence rank I-2p.

> Ecology & Life History

Potamopyrgus is an ovoviviparous brooder, unique among the hydrobioids.  Invasive populations often seem entirely composed of females, apparently triploid, reproducing by apomictic parthenogenesis.  Sexual reproduction is more common in New Zealand populations, however (Wallace 1985, 1992, Soper et al. 2012).  The reproductive variety demonstrated by Potamopyrgus populations have made them a favorite model organism for studies on the origin and adaptive value of sex, especially with regard to parasitism (Lively 1989, 1992, Dybdahl & Lively 1996, 1998, Koskella & Lively 2009).

One year is required for maturity in the best-studied German and Dutch populations, with iteroparous reproduction thereafter (Frenzel 1979, Dahl & Winther 1993, Dorgelo et al. 2014).  This is life cycle Hi of Dillon (2000: 156-162).  In milder environments maturity may be reached in as little as 3 – 6 months, however, and subsequent reproduction continuous (Winterbourn 1970a).  McKenzie and colleagues (2013) reported that maturity was reached at approximately 3.2 mm standard shell length in an introduced Colorado population, with up to 70 embryos per brood sack.

Potamopyrgus diet seems to be extremely broad, ranging from diatoms and algae through aquatic macrophytes and detritus of terrestrial origin, up to the decaying tissues of other aquatic invertebrates (Reavell 1980, Hanlon 1981, Haynes & Taylor 1984, Winterbourn & Fegley 1989, Bilka & Levri 2013).

Substantial concern has been expressed regarding the ecosystem effects of invasive Potamopyrgus populations (Kjeldsen 1996), focusing especially the possibility that they might compete with elements of the native fauna.  Kerans et al. (2005) found little field evidence of this phenomenon, although the experiments of Riley & Dybdahl (2015) suggest that competition with native hydrobiid populations is possible at low resource levels.  Predators include triclads (Reynoldson & Piearce 1979) and various fishes (Hartley 1948, Vinson & Baker 2008).  A great variety of trematode parasites have been documented from Potamopyrgus populations (e.g. Winterbourn 1974, Dybdahl & Lively 1998, Levri et al. 2007).

> Taxonomy & Systematics

European populations of P. antipodarum were initially described as Hydrobia jenkinsi by E. A. Smith (1889), subsequently split to the genus Potamopyrgus.  Winterbourn (1970b, 1972) was the first to connect the European populations to their New Zealand source, synonymizing the nomen jenkinsi under antipodarum (Gray 1843).

Some Potamopyrgus populations demonstrate striking dimorphism (or polymorphism) in shell form, varying in shell robustness as well as in the presence or absence of periostracum spines (Haase 2003).  Kistner & Dybdahl (2014) documented parallel variance in shell shape between P. antipodarum and the native hydrobiid Pyrgulopsis robusta in the Snake River of Idaho, apparently in response to water flow variation.  Hoy & Rodriguez (2013) have documented striking levels of intragenomic ribosomal sequence variation in Oregon populations, correlating the phenomenon with polyploidy.

Potamopyrgus is now classified in the Tateidae, an Australasian taxon recently raised to the family level by Wilke and colleagues (2013). 

> Maps and Supplementary Resources

• Potamopyrgus distribution in Atlantic drainages (2023)

> Essays

• I posted a national round-up of Potamopyrgus news in 19Sept08,  Invaders Great and Small, together with some general thoughts on the biology of invasive species.
• See my blog post of 19Nov13 for an essay announcing the discovery of Potamopyrgus in US Atlantic Drainages.
• Boom-and-bust cycles in western populations of Potamopyrgus were mentioned parenthetically in my Bellamya essay of 5Aug14, Just Before The Bust.
• Earlier versions of this website, online until August of 2016, adopted the large, broadly-inclusive concept of the Hydrobiidae (sl) following Kabat & Hershler (1993).  More recently the FWGNA project has shifted to the Wilke et al. (2013) classification system, distinguishing a much smaller Hydrobiidae (ss) and elevating many hydrobioid taxa previously ranked as subfamilies to the full family level.  For more details, see The Classification of the Hydrobioids.
• The 2017 discovery of a second Atlantic-drainage population of Potamopyrgus, this in the Gunpowder River of Maryland, was featured in my blog post of 13June18, Invasive Species Updates.  There's also an in situ photo courtesy of Matt Ashton, MD-DNR.
• I reported the third Atlantic-drainage population of New Zealand Mud snails in my post of  9July18, Potamopyrgus in New Jersey.

> References

Bilka, R. H. and E. P. Levri. 2013.  The invasive New Zealand mud snail (Potamopyrgus antipodarum) grows faster when consuming pariphyton compared to detritus.  Journal of the Pennsylvania Academy of Sciences 87: 125 - 128.
Bondesen, P. and E. W. Kaiser. 1949. Hydrobia (Potamopyrgus) jenkinsi (Smith) in Denmark illustrated by its ecology. Oikos 1:252-281.
Cheng, Y.W., and L.L. LeClair.  2011.  A quantitative evaluation of the effect of freezing temperatures on the survival of New Zealand mudsnails (Potamopyrgus antipodarum Gray, 1843), in Olympia Washington's Capitol Lake.  Aquatic Invasions  6(1):47-54.
Dahl, A. and L. B. Winther. 1993. Life-history and growth of the prosobranch snail Potamopyrgus jenkinsi in Lake Esrom, Denmark. Verh. Internat. Verein. Limnol. 25:582-586.
Dillon, R. T., Jr.  2000.  The Ecology of Freshwater Molluscs.  Cambridge University Press, 509 pp.
Dorgelo, J. 1991. Growth, food and respiration in the prosobranch snail Potamopyrgus jenkinsi (E. A. Smith) Hydrobiidae, Mollusca). Verh. Internat. Verein. Limnol. 24:2947-2953.
Dorgelo, J., H.G. van der Geest, and E.R Hunting. 2014.  Dynamics of natural populations of the dertitivorous mudsnail Potamopyrgus antipodarum (Gray) (Hydrobiidae) in two interconnected Lakes differing in trophic state.  SpringerPlus  3(736):1-9.
Dybdahl, M. F. and D. M. Drown. 2011.  The absence of genotypic diversity in a successful parthenogenic invader.  Biological Invasions 13: 1663-1672.
Dybdahl, M. F. and C. M. Lively. 1995a. Diverse, endemic and polyphyletic clones in mixed populations of a freshwater snail (NZ mudsnail). Journal of Evolutionary Biology 8:385-398.
Dybdahl, M. F. and C. M. Lively. 1995b. Host-parasite interactions: infection of common clones in natural populations of a freshwater snail (NZ mudsnail). Proceedings of the Royal Society of London 260:99-103.
Dybdahl, M. F. and C. M. Lively. 1996. The geography of coevolution: comparative population structures for a snail and its trematode parasite. Evolution 50:2264-2275.
Dybdahl, M.F. and C.M. Lively. 1998. Host-parasite coevolution: evidence for rare
advantage and time-lagged selection in a natural population. Evolution 52:1057-1066.
Fromme, E. A. and M. F. Dybdahl. 2006.  Resistance in introduced populations of a freshwater snail to native range parasites.  J. Evol. Biol. 19:1948-1955.
Frenzel, P.  1979.  Untersuchungen zur Biologie und populationsdynamik von Potamopyrgus jenkinsi (Smith) im litoral des Bodensees.  Arch. Hydrobiol. 85: 448-464.
Haase, M. 2003. Clinal variation in shell morphology of the freshwater gastropod Potamopyrgus antipodarum along two hill-country streams in New Zealand.  Journal of the Royal Society of New Zealand 33: 549-560.
Hanlon, R. D. G. 1981. The influence of different species of leaf litter on the growth and food preference of the Prosobranch Mollusk Potamopyrgus jenkinsi (E. A. Smith). Arch. of Hydrobiol. 91:463-474.
Hartley P.  1948.  Food and feeding in a community of freshwater fishes.  J. Anim. Ecol. 17: 1-14.
Hartzell, S.M. and J.R. Frederick. 2023. First records of the invasive New Zealand mudsnail (Potamopyrgus antipodarum) in the Potomac River Basin.  Northeastern Naturalist 30 (1): N13 - N16.
Hartzell, S.M. and N. Macelko. 2022. Range expansion of the invasive New Zealand Mudsnail (Potamopyrgus antipodarum) in the Susquehanna and Delaware River Basins of Pennsylvania.  Journal of the Pennsylvania Academy of Science 96: 36 - 45.
Hartzell, S.M. and M.K. Shank. 2024.  Chemical variables predicting colonization risk of the invasive New Zealand mudsnail (Potamopyrgus antipodarium) in Pennsylvania's flowing waters.  Hydrobiologia, https://doi.org/10.1007/s10750-024-05711-2
Haynes, A. and B. J. R. Taylor. 1984. Food finding and food preference in Potamopyrgus
 jenkinsi (E. A. Smith) (Gastropoda: Prosobranchia). Arch. Hydrobiol. 100:479-491.
Haynes, Alison, B. J. R. Taylor, and M. E. Varley. 1985. The influence of the mobility of
Potamopyrgus jenkinsi (Smith, E. A.) (Prosobranchia: Hydrobiidae) on its spread.  Arch. Hydrobiol. 103:497-508.
Herbst, D.B., M.T. Bogan and R.A. Lusardi. 2008.  Low specific conductivity limits growth and survival of the New Zealand mud snail from the upper Owens River, California.  Western North American Naturalist 68: 324 - 333.
Hershler, R., H-P. Liu and W. H. Clark. 2010.  Microsatellite evidence of invasion and rapid spread of divergent New Zealand mudsnail (Potamopyrgus antipodarium) clones in the Snake River basin, Idaho, USA.  Biological Invasions 12: 1521 - 1532.
Heywood, J. and Edwards R.  1962.  Some aspects of the ecology of Potamopyrgus jenkinsi Smith.  J. Anim. Ecol. 31: 239-250.
Hoy, M.S., and R.J. Rodriguez.  2013.  Intragenomic sequence variation at the ITS1-ITS2 region and at the 18S and 28S nuclear ribosomal DNA genes of the New Zealand mud snail, Potamopyrgus antipodarum (Hydrobiidae: Mollusca).  Journal of Molluscan Studies  79(3):205-217.
Kabat, A.R., and R. Hershler (1993) The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea): review of classification and supraspecific taxa. Smithsonian Contributions to Zoology 547:1-94. 
Kerens, 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.  J. N. Am. Benthol. Soc. 24: 123-138.
Kistner, E.J., and M.F. Dybdahl.  2014.  Parallel variation among populations in the shell morphology between sympatric native and invasive aquatic snails.  Biological Invasions  16(12):2615-2626.
Kjeldsen, K. 1996. Regulation of algal biomass in a small lowland stream: field experiments on the role of invertebrate grazing, phosphorus and irradiance.  Freshwater Biology 36:535-546.
Koskella, B., and C.M. Lively.  2009.  Evidence for negative frequency-dependent selection during experimental coevolution of a freshwater snail and a sterilizing trematode.  Evolution  63(9):2213-2221.
LeClair, L.L., and Y.W. Cheng.  2011.  A review of salinity tolerances for the New Zealand mudsnail (Potamopyrgus antipodarum, Gray 1843) and the effect of a controlled saltwater backflush on their survival in an impounded freshwater lake.  Journal of Shellfish Research  30(3):905–914.
Levri, E.P., A.A. Kelly and E. Love. 2007. The invasive New Zealand mud snail (Potamopyrgus antipodarum) in Lake Erie.  Journal of Great Lakes Research 33: 1–6.
Levri, E.P., A.C. Krist, R. Bilka, and M.F. Dybdahl (2014)  Phenotypic plasticity of the introduced New Zealand mud Snail, Potamopyrgus antipodarum, compared to sympatric native snails.  PLoS ONE  9(4):e93985, 1-6.
Levri, E. P., Lunnen, S., Itle, C., Martin, T., Kincade, B., DeLisser, M., and Mosquea, L. 2007.  Parasite-induced alteration of diurnal rhythms in a freshwater snail. Journal of Parasitology 93(2): 231-237.
Levri, E. P., Dermott, R. M, Lunnen, S. J., Kelly, A. A. and Ladson, T.  2008.  The distribution of the invasive New Zealand mud snail (Potamopyrgus antipodarum) in Lake Ontario.  Aquatic Ecosystem Health and Management 11: 412-421.
Lively, C.M. 1989. Adaptation by a parasitic trematode to local populations of its host. Evolution 46:1663-1671.
Lively, C. M. 1992. Parthenogenesis in a freshwater snail: reproductive assurance versus parasitic release. Evolution 46:907-913.
McKenzie, V.J., W.E. Hall, and R.P. Guralnick.  2013.  New Zealand mudsnails (Potamopyrgus antipodarum) in Boulder Creek, Colorado: environmental factors associated with fecundity of a parthenogenic invader.  Canadian Journal of Zoology  91(1):30-36.
Moore, J. W., D. B. Herbst, W. N. Heady and S. M. Carlson 2012. Stream community and ecosystem responses to the boom and bust of an invading snail. Biological Invasions 14: 2435-2446.
Ponder, W. F. 1988. NZ mudsnail, a Molluscan colonizer of Europe and Australia. Journal of Molluscan Studies 54:271-286.
Poznańska, M., T. Kakareko, T. Gulanicz, L. Jermacz, and J. Kobak.  2015.  Life on the edge: survival and behavioural responses of freshwater gill-breathing snails to declining water level and substratum drying.  Freshwater Biology  60(11):2379-2391.
Reavell, P.  1980.  A study of the diets of some British freshwater gastropods.   J. Conchol. 30: 253-71.
Reynoldson T. and Piearce, B. 1979.  Predation on snails by three species of triclad and its bearing on the distribution of Planaria torva in Britain.  J. Zool. 189: 459-84.
Ribi, G. 1986. Within-lake dispersal of the prosobranch snails, Viviparus ater and Potamopyrgus jenkinsi. Oecologia 69:60-63.
Riley, L.A., and M.F. Dybdahl.  2015.  The roles of resource availability and competition in mediating growth rates of invasive and native freshwater snails.  Freshwater Biology  60(7):1308-1315.
Soper, D.M., L.F. Delph, and C.M. Lively. 2012. Multiple paternity in the freshwater snail, Potamopyrgus antipodarum.  Ecology and Evolution 2: 3179-3185.
Todd, M. 1964.  Osmotic balance in Hydrobia ulvae and Potamopyrgus jenkinsi (Gastropoda: Hydrobiidae)  J. Exp. Biol. 41: 665-77.
Vinson, M. R. and Baker, M. A.  2008.  Poor growth of rainbow trout fed New Zealand mudsnails Potamopyrgus antipodarum. North American Journal of Fisheries Management 28: 701-709.
Wallace, C. 1979. Notes on the occurrence of males in populations of Potamopyrgus jenkinsi. Journal of Molluscan Studies 45:61-67.
Wallace, C. 1978. Notes on the distribution of sex and shell characteristics in some Australian populations of Potamopyrgus (Gastropoda: Hydrobiidae). Journal of the Malacological Society of Australia 4:71-76.
Wallace, C.  1985.  On the distribution of the sexes of Potamopyrgus jenkinsi.  J. Moll. Stud. 51: 93-107.
Wallace, C. 1992. Parthenogenesis, sex, and chromosomes in Potamopyrgus. Journal of Molluscan Studies 58:93-107.
Wilke T., Haase M., Hershler R., Liu H-P., Misof B., Ponder W. (2013)  Pushing short DNA fragments to the limit: Phylogenetic relationships of “hydrobioid” gastropods (Caenogastropoda: Rissooidea).  Molecular Phylogenetics and Evolution 66: 715 – 736.
Winterbourn, M. J. 1970a. Population studies on the New Zealand freshwater gastropod, NZ mudsnail (Gray). Proceedings of the Malacological Society of London 39: 139-149.
Winterbourn, M. J. 1970b. The New Zealand species of Potamopyrgus (Gastropoda: Hydrobiidae). Malacologia 10:283-321.
Winterbourn, M. J. 1972. Morphological variation of Potamopyrgus jenkinsi (Smith) from England and a comparison with the New Zealand species NZ mudsnail (Gray). Proceedings of the Malacological Society of London 40:133-145.
Winterbourn, M. J. 1974. Larval trematoda parasitising the New Zealand species of Potamopyrgus (Gastropoda: Hydrobiidae). Mauri Ora 2:17-30.
Winterbourn, M. J. and A. Fegley. 1989. Effects of nutrient enrichment and grazing on periphyton assemblages in some spring-fed, South Island streams. New Zealand Natural Sciences 16:57-65.
Zaranko, D. T., D. G. Farara, and F. G. Thompson. 1997. Another exotic Mollusk in the Laurentian Great Lakes: the New Zealand native NZ mudsnail (Gray 1843) Gastropoda, Hydrobiidae). Canadian Journal of Fisheries and Aquatic Sciences 54: 809-814.