Invasion History

First Non-native North American Tidal Record: 1962
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1962

General Invasion History:

Pisidium amnicum is a small deposit-feeding freshwater bivalve native to Eurasia (Herrington 1962). Published records range from Spain and the British Isles to Finland and the Kola Peninsula (Russia) and east to the Ussuri River Basin in the Far East of Russia (Zoological Record SP database search 2009). It occurs in oligohaline waters of the Baltic Sea (Remane and Schleiper 1971; Zettler and Daunys 2007).

North American Invasion History:

Invasion History on the East Coast:

Pisidium amnicum was first recorded in North America in 1897 in Lake Ontario at Charlotte, New York (Baker 1897, cited by Mills et al. 1993). Possible vectors of introduction include dry ballast and marsh grasses used as packing materials for fragile European goods. It is now found throughout the Great Lakes-St. Lawrence system, from Thunder Bay, Lake Superior (Grigorovich et al. 2003) to Lakes Huron, Erie, and Ontario (Herrington 1962) and the upper St. Lawrence Estuary. In the St. Lawrence estuary, it ranges from the Lac St. Pierre Dam at the head of tide to Quebec City (Vincent 1979; Vincent et al. 1981).

Pisidium amnicum was reported in the tidal fresh Hudson River in 1983 near Glenmont, Albany County, at River Miles 134-141 (Simpson 1984, cited by Strayer 1987, Mills et al. 1997). Its abundance in benthic samples is very low (Strayer and Smith 2001). This clam could have been introduced to the Hudson River in dry ballast, packing material, ballast water sediment, or through connecting canals from the Great Lakes-St. Lawrence system. Herrington (1962) listed the Delaware River, New Jersey as a location for this species. We've found no other information on the presence of this species in the Delaware River.


Pisidium amnicum is a member of the family Pisidiidae (Pea Clams), which are small freshwater clams ranging from 1-25 mm in length. In the genus Pisidium, the beak is located posterior to the midpoint of the shell, at about 2/3 of the shell's length. The muscular foot is large, and only the anal siphon is developed, while the oral siphon is reduced to a cleft (Martin 1998). In P. amnicum, the shell is oval with a height of 0.74 - 0.81 mm. The beak is medium in height. The anterior dorsal edge is slightly curved, while the posterior end slopes more steeply and is more strongly curved. The second cardinal tooth is a thick peg flattened on the anterior side. The third cardinal tooth is curved, and fits around the 2nd cardinal. The shell has a shiny yellow or brown periostracum (Clarke 1981, Herrington 1962). Pisidium amnicum is considered a large member of its genus. The specimens listed by Herrington (1962), from Canada and Denmark ranged from 9.7 to 11.9 mm in length. Adult P. amnicum in a St. Lawrence River estuary ranged from 4.2 to 8.5 mm (Vincent et al. 1981).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Bivalvia
Subclass:   Heterodonta
Order:   Veneroida
Superfamily:   Corbiculoidea
Family:   Pisidiidae
Genus:   Pisidium
Species:   amnicum


Pisidium amnicum (Jenyns, 1832)
Tellina amnicum (Müller, 1774)

Potentially Misidentified Species

Pisidium adamsi
Native to North America (Martin 1998)

Pisidium caesertanum
Cosmopolitan? (Martin 1998)

Pisidium dubium
Native to North America (Martin 1998)



Pisidium amnicum is a small deposit-feeding freshwater clam, which burrows in the sediment of rivers, streams, and lakes. Pea Clams are hermaphroditic and oviviparous, 'giving birth' to shelled juveniles (Martin 1998). Brood size in various P. amnicum populations ranges from 1 to 41, with an average of 9 to 13 (Holopainen and Hanski 1986). Pisidium amnicum in the tidal fresh St. Lawrence River estuary reach maturity at 1 year of age, and reproduce in the 2nd and 3rd years of their 3-year life span (Vincent et al. 1981).

Pisidium amnicum is a freshwater species, but occurs at salinities of at least 1 PSU (Remane and Schleiper 1971; Zettler and Daunys 2007; Sousa et al. 2011). Pea clams feed by filtering detritus and particles in interstitial waters (Thorp and Covich 2001). As a group, pea clams are an important food for benthic invertebrates and fishes (Martin 1998).


Detritus, benthic diatoms


Corbicula fluminea

Trophic Status:

Deposit Feeder



General HabitatNontidal FreshwaterNone
General HabitatUnstructured BottomNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Tidal RangeSubtidalNone
Vertical HabitatEndobenthicNone

Tolerances and Life History Parameters

Minimum Salinity (‰)0This is a freshwater organism.
Maximum Salinity (‰)1Field, Baltic Sea, Germany (Remane and Schleiper 1971)
Minimum Reproductive SalinityNoneThis is a freshwater organism.
Minimum Length (mm)4.2Vincent et al. 1981
Maximum Length (mm)11.9Herrington 1962
Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNoneNontidal Limnetic-Oligohaline

General Impacts

No impacts have been reported for Pisidium amnicum in North American waters.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
GL-III Lake Ontario 1897 Def Estab
GL-II Lake Erie 1962 Def Estab
GL-I Lakes Huron, Superior and Michigan 1962 Def Estab
M060 Hudson River/Raritan Bay 1983 Def Estab
M090 Delaware Bay 1962 Def Unk
NA-S3 None 1977 Def Estab
B-IX None 0 Native Estab
B-XIII None 0 Native Estab
B-VII None 0 Native Estab
L113 _CDA_L113 (Irondequoit-Ninemile) 1897 Def Estab
L099 _CDA_L099 (Cuyahoga) 1962 Def Estab
L068 _CDA_L068 (Au Sable) 1962 Def Estab
L013 _CDA_L013 (St. Louis River) 1985 Def Estab
L127 _CDA_L127 (English-Salmon) 1972 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Clarke, Arthur H. (1981) <missing title>, National Museum of Natural Sciences, Ottawa. Pp. <missing location>

Grigorovich, Igor A; Korniushin, Alexei V.; Gray, Derek K.; Duggan, Ian C.; Colautti, Robert I.; MacIsaac, Hugh J. (2003) Lake Superior: an invasion coldspot?, Hydrobiologia 499: 191-210

Herrington, H. B. (1962) A revision of the Sphaeriidae of North America (Mollusca: Pelecypoda), Miscellaneous Publications, Museum of Zoology, University of Michigan 118: 1-74

Holopainen, Ismo J.; Hanski, Ilkka (1986) Life history variation in Pisidium, Holarctic Ecology 9: 85-98

Kuiper, J. G. J.; Okland, Karen anna; Knudsen, Jorgen; Koli, Lauri; Von Proschwitz, Ted; Valovirta, Ilmari (1989) Geographical distribution of the small mussels (Sphaeriidae) in north Europe (Denmark, Faeroes, Finland, Iceland, Norway, and Sweden), Annales Zoologici Fennici 26: 73-101

Marsden, J. Ellen; Hauser, Michael (2009) Exotic species in Lake Champlain, Journal of Great Lakes Research 35: 250-265

Martin, Scott M. (1998) Freshwater fingernail and pea clams (Bivalvia: Veneroida: Sphaeriidae) of Maine, Northeastern Naturalist 5: 29-60

Mills, Edward L.; Leach, Joseph H.; Carlton, James T.; Secor, Carol L. (1993) Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions., Journal of Great Lakes Research 19(1): 1-54

Mills, Edward L.; Scheuerell, Mark D.; Carlton, James T.; Strayer, David (1997) Biological invasions in the Hudson River: an inventory and historical analysis., New York State Museum Circular 57: 1-51

Remane, Adolf; Schleiper, Carl C. (1971) Biology of Brackish Water, In: (Eds.) . , New York. Pp. 1-210

Sousa, Ronaldo; Ilarri, Martina; Souza, Allan T.; Antunes, Carlos; Guilhermino, Lucia (2011) Rapid decline of the greater European peaclam at the periphery of its distribution, Annales de Limnologie 47: 211-219

Strayer, David (1987) Ecology and zoogeography of the freshwater mollusks of the Hudson River Basin, Malacological Review 20: 1-68

Strayer, David L ; Smith, Lane C. (2001) The zoobenthos of the freshwater tidal Hudson River and its response to the zebra mussel (Dreissena polymorpha) invasion, Archiv fur Hydrobiologie 139(1): 1-52

Thorp, James H.; Covich, Alan P. (2001) <missing title>, Academic Press, San Diego CA. Pp. <missing location>

Trebitz, Anett S. and 5 authors (2010) Status of non-indigenous benthic invertebrates in the Duluth-Superior Harbor and the role of sampling methods in their detection, Journal of Great Lakes Research 36: 747-756

Vincent, B. (1979) Etude du benthos d'eau douce dans le haut-estuaire du Saint-Laurent (Quebec), Canadian Journal of Zoology 57: 2171-2182

Vincent, B., Vaillancourt, G., Lafontaine, N. (1981) Cycle de développement, croissance et production de Pisidium amnicum (Mollusca: Bivalvia) dans le Saint-Laurent (Québec), Canadian Journal of Zoology 59: 2350-2359

Zettler, Michael L.; Daunys, Darius (2007) Long-term macrozoobenthos changes in a shallow boreal lagoon: Comparison of a recent biodiversity inventory with historical data., Limnologica 37: 170-185