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You are viewing an archived site. The Chesapeake Bay Introduced Species Database project ended in 2020 and the database is no longer receiving updates. Learn more…
Image of Assiminea succinea

Assiminea succinea

Mollusks-Gastropods

salt marsh snail

Atlantic Assiminea is a tiny (2.5 mm) salt marsh snail found along the Atlantic coast from Brazil to Massachusetts. Because this species is so tiny it is easily overlooked and the original range is uncertain. It was first seem in Brooklyn, NY in the mid 1800s suggesting that it could be native to the Mid-Atlantic region, however, it wasn’t seen in the Chesapeake Bay until 1935 and its frequent association with docks and ports suggesting that it may be introduced. Since we can’t say for sure if it’s native or introduced we consider it cryptogenic in Chesapeake Bay and other estuaries north of Cape Hatteras. Other snails of similar size and habit (Ovatella myosotis) were collected in the bay in the early as 1900s but it is not very common and could have been overlooked. Atlantic Assiminea was first seen on Smith's Island and Fisherman's Island in North Hampton County VA in 1935 and Shell Bay, Chincoteague Bay, and several others in the area in 1950. In 1952 it was collected in the Potomac River and from the Rappahannock in 1972. JPE Morrison, Smithsonian malacologist, attributed its appearance in the Bay to the oyster shell trade in which oyster shell from the Carolinas was planted in the Bay to encourage oyster spatfall.

Image Credit: Dr Stan Boul

Description Taxonomy Invasion History Ecology Impacts References

Description

Synonymy - Names with describers: Paludina succinea Pfieffer 1840; Assiminea Heming 1828; A. auberiana of Dall, auct. non Orbigny, 1842; C. concinna; P. concolor C. B. Adams 1850; C. modesta Lea 1845; A. grayana Verrill 1880 non Leach; S. succinea (Gray nomen dubium); A. succinea vina Marcus and Marcus 1965.

Verrill (1880a) initially identified his snails as the European species A. grayana.

Taxonomy

Kingdom Phylum Class Order Family Genus
Animalia Mollusca Gastropoda Monotocardia Assimineidae Assiminea

Synonyms

Paludina succinea; Assiminea auberiana; Cingula concinna; Phasianella concolor; Rissoa succinea; Cingula modesta; Assiminea grayana; Syncera succinea; Syncera modesta; Assiminea succinea vina

Invasion History

Chesapeake Bay Status

First Record Population Range Introduction Residency Source Region Native Region Vectors
1934 Established Stable Cryptogenic Regular Resident Western Atlantic Western Atlantic Fisheries(Oysters-accidental),Shipping(Dry Ballast)

History of Spread

Assiminea succinea (Atlantic Assiminea) is found along the Atlantic coast from Brazil to MA, but the range of the species may have been extended northwards by shipping. The original range of A. succinea is uncertain. This species is small (2.5 mm) and could be overlooked but is semi-terrestrial habits and occurrence in the upper intertidal increases chances of collection and also makes it a good candidate for dry ballast transport. Its early appearance at Brooklyn, NY (Lea 1845) suggests it could be native to the Mid-Atlantic region, but late first collections at other locations including Chesapeake Bay, and its frequent association with docks and ports suggests introduced status (Verrill 1880a). We consider this species to be cryptogenic in Chesapeake Bay and other estuaries north of Cape Hatteras. Snails of similar size and habit (Ovatella myosotis) were collected as early as 1900 from Chesapeake Bay, but A succinea could have beeen overlooked.

North American records are summarized below:

Cuba - 1840, Type locality; (Pfieffer 1840; cited by Rosenberg 1995 as Paludina succinea)

West Florida - 1842 ( Maury 1842; cited by Rosenberg 1995; as Assiminea auberiana)

Florida, East Coast - 1958 [(probably not a 1st record) - United States National Museum of Natural History Special Collections]

South Carolina - Fort Johnson (Kurtz 1860); 1960 (United States National Museum of Natural History Collections)

Bermuda - 1955 (probably not a 1st record) (United States National Museum of Natural History Collections)

Chesapeake Bay - as Syncera succinea, 1935 (Wass 1972); see below; 'Has apparently been transferred by oyster shell traffic' (Wass 1972).

Brooklyn NY - as Cingula modesta (Lea 1845)

Cold Spring Harbor, NY - 1898, as Assiminea modesta; 'It certainly is not common and appears to be very highly local, which would explain why a shell so conspicuous for everything except size has been so overlooked (Balch 1899).

Connecticut - as Rissoa modesta, 1851 Stimpson (1851)

Newport, RI - as Assiminea grayana, 1880 'in the docks,' 'Whether these shells have been accidentally introduced at that point by shipping; or are really indigenous, cannot at present be determined' (Verrill 1880a).

Massachusetts - found 1968-89 on Cape Cod Bay, at Sandwich and Scituate, and on Boston Harbor, East Boston (Baranowski 1971).

Chesapeake Records (detailed):

Northern Bay Mouth - (Hog Island; Chincoteague Bays); 1935 Smith's Island Northhampton County VA; 1950 Shell Bay; Willis Wharf; Bayford; Oyster; Cherrystone; Chincoteague Bay; Accomac Co. VA (United States National Museum of Natural History Wass 1972).

Lower Bay - 1935 Fisherman's Island, Northampton County, VA.; Willoughby Bay; Willoughby Spit; Norfolk County, VA (at mouth of James River); 1945 Western Branch Elizabeth River; Portsmouth VA (Norfolk County). 1950 Crisfield MD (Somerset County) (Allen 1954a; Wass 1972; United States National Museum of Natural History Collections)

Rappahannock River - (lower) (Mollusk VA; Lancaster County) (Wass 1972)

Potomac River - 1959 (lower) Huggins Point; Leonardtown, MD (Wass 1972)

History References - Allen 1954a; Balch 1899; Baranowski 1971; Kurtz 1860; Lea 1845; Rosenberg 1995; Stimpson 1851; United States National Museum of Natural History Collections; Verrill 1880a; Wass 1972

Invasion Comments

Probable Vector into Chesapeake Bay - Assiminea succinea has been suggested to have been spread 'by oyster shell traffic' (Wass 1972), presumably with dead shells used as cultch which would be stored on shore. This snail is found in the upper intertidal (Balch 1899) and would not usually be associated with live oysters.

Ecology

Environmental Tolerances

For SurvivalFor Reproduction
Minimum Maximum Minimum Maximum
Temperature (ºC)
Salinity (‰)
Oxygen
pH
Salinity Range oligo-eu

Age and Growth

Male Female
Minimum Adult Size (mm)
Typical Adult Size (mm)
Maximum Adult Size (mm) 2.5 2.5
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
Fertilization Type(s)
More than One Reproduction
Event per Year
Reproductive Startegy
Egg/Seed Form

Impacts

Economic Impacts in Chesapeake Bay

Because of its small size and low abundance, Assiminea succinea has no economic importance in Chesapeake Bay.

Economic Impacts Outside of Chesapeake Bay

Because of its small size and low abundance, Assiminea succinea has no economic importance on the Atlantic Coast.

Ecological Impacts on Chesapeake Native Species

Assiminea succinea is a potential competitor with the native pulmonate Melampus bidentatus, but this has not been documented. Melampus bidentatus seems to be much more abundant in marshes than A. succinea (Allen 1954a; Wass et al. 1972).

Ecological Impacts on Other Chesapeake Non-Native Species

Assiminea succinea is a potential competitor with the introduced pulmonate Myosotella myosotis and the cryptogenic Melampus floridanus. Both species seem to be much more abundant in marshes than A. succinea (Allen 1954a; Morrison 1951; Wass 1972). In California marshes, Berman and Carlton (1991) found no interactions between A. californica and M. myosotis, and concluded that these algivorous and detritvorous snails were not resource-limited. This conclusion seems likely to apply to A. succinea as well.

References

Allen, J. Frances (1954) Notes on the gastropods collected in the vicinity of Crisfield, Maryland, The Nautilus 67: 92-94

Balch, Francis Noyes (1899) List of marine mollusca of Coldspring Harbor, Long Island, with descriptions of one new genus and two new species of nudibranchs, Proceedings of the Boston Society of Natural History 29: 133-163

Baranowski, Walter P. (1971) New northern range extension of the range of Assiminea modesta (H.C. Lea), Nautilus 84: 143-144

Berman, Jody; Carlton, James T. (1991) Marine invasion processes: Interactions between native and introduced marsh snails, Journal of Experimental Marine Biology and Ecology 150: 267-281

Fowler, Bruce H. (1980) Reproductive biology of Assiminea californica (Tryon , 1865), The Veliger 23: 2

Fretter, Vera; Graham, Alastair (1962) British prosobranch molluscs: their functional anatomy and ecology, In: (Eds.) . , London. Pp.

Johnson, Charles W. (1915) Fauna of New England. 13. List of the Mollusca, Occasional Papers of the Boston Society of Natural History 7: 1-223

Kurtz, John D. (1860) Catalogue of recent marine shells found on the coasts of North and South Carolina, , Portland, NC. Pp.

Lea, Henry C. (1845) Descriptions of some new species of marine shells, inhabiting the coast of the United States, Proceedings of the Boston Society of Natural History 1: 204-205

1995-2023 Malacolog 4.1. http://www.acnatsci.org

Stimpson, William (1851) Shells of New England. A revision of the synonymy of the testaceous mollusks of New England, , Boston. Pp. 56

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

Verrill, A. E. (1880b) Occurrence at Newport, R. I., of two littoral species of European shells not before recorded as American, American Journal of Science 20: 250-251

Wass, Melvin L. (1972) A checklist of the biota of lower Chesapeake Bay, Special Scientific Report, Virginia Institute of Marine Science 65: 1-290

Direct questions and comments to chesnemo@si.edu.

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