Description
The Physidae is a taxonomically very difficult family. P. acuta is nearly identical to the abundant native species P. heterostropha in shell morphology; the species are distinguished by genital anatomy (Te 1978). Beetle's (1973a) reported specimens from VA were identified by Dr. William Clench.
A recent study indicates that P. acuta may be conspecific with the North American species P. heterostropha and P. integra. Populations of all 3 "species" were interfertile, and hybrids were not different from controls in survival rand reproductive output (Dillon et al. 2002). Dillon et al. (2002) suggest that P. acuta is a morphologically variable species, including P. heterostropha and P. integra, and is native to North America. This species is presumed to have been introduced to Europe and the Old-World tropics (Dillon et al. 2002).
Taxonomy
| Kingdom | Phylum | Class | Order | Family | Genus |
|---|---|---|---|---|---|
| Animalia | Mollusca | Gastropoda | Bassomatophora | Physidae | Physella |
Synonyms
Invasion History
Chesapeake Bay Status
| First Record | Population | Range | Introduction | Residency | Source Region | Native Region | Vectors |
|---|---|---|---|---|---|---|---|
| 1973 | Established | Unknown | Native | Unconfirmed | Europe | Eurasia | Shipping(unspecified),Ornamental(Aquatic Plant) |
History of Spread
Physella acuta (European Physa) is a freshwater snail, generally believed to be native to southern Europe, Mediterranean Africa, and tropical to warm-temperate Asia. It has been widely introduced to many parts of the world including Australia and Hawaii'i (Burch 1982; Te 1978). The extent of its invasion in North America is not known because it has been rarely reported due to its morphological similarity to P. heterostropha. Te (1978) suggests that extensive hybridization with P. heterostropha may have obscured P. acuta's occurrence. Burch (1982) lists it as 'introduced into Australia, HI, and perhaps parts of the continental United States.' It's not clear if his uncertainty is due to identification or the establishment of this species.
A recent study indicates that P. acuta may be conspecific with the North American species P. heterostropha and P. integra. Populations of all 3 "species" were interfertile, and hybrids were not different from controls in survival and reproductive output (Dillon et al. 2002). Dillon et al. (2002) suggest that P. acuta is a highly variable species in morphology and life history, which includes "P. heterostropha" and "P. integra", and is native to North America. This species is presumed to have been introduced to Europe and the Old-World tropics. Given the divergence of opinions on the origin and systematics of this snail, we consider it cryptogenic in North America.
Physella acuta was first reported from Cambridge MA in tanks being used for the growth of algae (Clench 1934). Specimens at the Academy of Natural Sciences of Philadelphia were collected in Harry's Brook, Princeton NJ (Dundee 1974).
Physella acuta has not been reported from tidal waters of Chesapeake Bay, but given its widespread records in coastal VA, it may occur there. Physa sp. were reported from the tidal James River by Diaz (1994).
Lower Bay drainages - Beetle (1973a) reported P. acuta from several freshwater locations near the lower Chesapeake Bay, including Hampton, Newport News, York County, and Virginia Beach.
Potomac river- P. acuta was reported from Fairfax County (no location given; Beetle 1973c) and from pools adjacent to the C&O canal, 12 miles north of Washington D.C.(Dundee 1974).
History Refs- Beetle 1973a; Beetle 1973a; Burch 1982; Clench 1934; Dillon et al. 2002; Dundee 1974; Te 1978
Invasion Comments
Ecology
Environmental Tolerances
| For Survival | For Reproduction | |||
|---|---|---|---|---|
| Minimum | Maximum | Minimum | Maximum | |
| Temperature (ºC) | 3.0 | 40.0 | ||
| Salinity (‰) | 0.0 | 0.0 | ||
| Oxygen | ||||
| pH | ||||
| Salinity Range | fresh-oligo |
Age and Growth
| Male | Female | |
|---|---|---|
| Minimum Adult Size (mm) | ||
| Typical Adult Size (mm) | ||
| Maximum Adult Size (mm) | ||
| Maximum Longevity (yrs) | ||
| Typical Longevity (yrs |
Reproduction
| Start | Peak | End | |
|---|---|---|---|
| Reproductive Season | |||
| Typical Number of Young Per Reproductive Event |
|||
| Sexuality Mode(s) | |||
| Mode(s) of Asexual Reproduction |
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| Fertilization Type(s) | |||
| More than One Reproduction Event per Year |
|||
| Reproductive Startegy | |||
| Egg/Seed Form |
Impacts
Economic Impacts in Chesapeake Bay
Physella acuta (European Physa) has had no reported economic impacts in the Chesapeake region.
Economic Impacts Outside of Chesapeake Bay
In tropical regions, Physella acuta (European Physa) is important as a host for human and animal parasites (Te 1978).
Ecological Impacts on Chesapeake Native Species
The present occurrance and abundance of Physella acuta (European Physa) in the Chesapeake region is unknown, owing in part to its similarity to the abundant and widely distributed native P. heterostropha. Hybridization between the two has been suggested (Te 1978). If it has occurred, it does not appear to have affected the abundance of the native species (Burch 1982; Hamilton 1979).
References- Burch 1982; Hamilton 1979; Te 1978
Ecological Impacts on Other Chesapeake Non-Native Species
The present occurrance and abundance of Physella acuta (European Physa) is unknown, but it probably has no impacts on introduced snails or other biota.
References
Beetle, Dorothy E. (1973) Physa acuta in Virginia, Nautilus 87: 28Beetle, Dorothy E. (1973) Freshwater mollusks from coastal Virginia, Nautilus 87: 29
Beetle, Dorothy E. (1973) A checklist of the land and freshwater mollusks of Virginia, Sterkiana 49: 21-35
Burch, J. B. (1982) Freshwater Snails (Mollusca: Gastropoda) of North America, , Cincinnati. Pp.
Diaz, Robert J. (1994) Response of tidal freshwater macrobenthos to sediment disturbance, Hydrobiologia 278: 201-212
Dillon, Robert T. Jr; Wehrington, Amy R.; Rhett, J. Matthew; Smith, Thomas P. (2002) Populations of the European freshwater pulmonate Physa acuta are not reproductively isolated from American Physa heterostropha or Physa integra., Invertebrate Biology 12: 226-234
Dundee, Dee S. (1974) Catalog of introduced molluscs of eastern North America (North of Mexico), Sterkiana 55: 1-37
Gracio, Maria A. A. (1983) Distribution and habitats of six species of freshwater pulmonate snails in Algarve, southern Portugal, Malacological Review 16: 17-23
Hamilton, Suzanne (1979) Shell armor in freshwater gastropods: its protective advantages and potential liabilities, , College Park MD. Pp.
Tanveer, Akhtar (1992) Response to temperature and heat tolerance of some snails, Bangladesh Journal of Zoology 20: 257-268
Te, George A. (1978) A systematic study of the family Physidae (Bassomatophora: Pulmonata), , Ann Arbor. Pp.
Turgeon, D.D.; Bogan, A.E.; Coan, E.V.; Emerson, W.K.; Lyons, W.G.; Pratt, W.L.; Roper, E.F.E.; Scheltema, A.; Thompson, F.G.; Williams, J.D. (1988) Common and Scientific Names of Aquatic Invertebrates from the United States and Canada: Mollusks, , Bethesda, Maryland. Pp. 227 pages