> Habitat & Distribution
From a point of introduction in the Great Lakes, recent North American populations of B. tentaculata spread east to Quebec and west to Wisconsin, as well as south through the
Mohawk and Hudson Rivers (Clarke 1981, Jokinen 1992, Haynes et al.
2005). The population that arrived in the Potomac River of Virginia
in the 1930s apparently represents the southern limit of its range
(Pilsbry 1932).
The Potomac population seems to reach its maximum density at Great
Falls near Washington, DC. The snails do not seem as
well-adapted to slower, muddier, warmer, and presumably less oxygenated
environments. But further north Bithynia populations have colonized a wide variety of permanent waters, including
ponds, lakes, marshes, canals, and rivers, and occur on a variety of
substrates, including gravel, sand, clay, mud, rocks, and macroscopic
vegetation (Jokinen 1992, Haynes et al. 2005, Wojdak and Mittelbach
2007, Weeks et al. 2017). Bithynia thrives in both mesotrophic and eutrophic lakes, and
can dominate snail assemblages where nutrient levels are high (Clarke
1979, Harman & Forney 1970, Harman 2000). Populations are, however, apparently restricted to waters relatively
high in hardness. New York populations occurred in habitats with
a pH range of 6.6-8.4 and with calcium concentration ranges of 5-89 ppm
(Jokinen 1992). FWGNA incidence rank I-3p, peripheral.
> Ecology & Life History
While retaining the ancestral ability to graze the substrate (Clarke 1981), Bithynia has evolved a "food groove" at the base of its gill that allows it to filter-feed (Dillon 2000: 100-101). The relative importance of grazing and filter-feeding to the energy budget of the snail seems to depend on the environmental concentration of suspended particles (Tashiro 1982, Tashiro & Coleman 1982).
Life cycles can be completed in less than one year (Pinel-Alloul &
Magnin 1971) - exceptionally rapid for populations of freshwater
prosobranchs (Dillon 2000: 161-162). In New York, Jokinen (1992)
reported that egg laying can begin in May or June and continue into
July, and that some individuals born in spring may breed in the fall of
the same year. Eggs are deposited on hard substrates, with up to
77 eggs contained in each mass. Individuals appear to live up to
18 months, and possibly as long as 39 months. Analysis of the
productivity data developed by Mattice (1972) led Dillon (2000: 126 - 135) to
suggest that the B. tentaculata population of Oneida Lake (NY) might be R-adapted, displaying a reproductive effort over an order of magnitude greater than predicted from their body size.
Populations of B. tentaculata inhabiting rivers and lakes of the Upper Midwest serve as intermediate
hosts for digenean flukes that have been implicated in massive
waterfowl die-offs. (See my essay of 14Nov07 from the link
below.) Some interesting experiments involving the defensive
behaviors displayed by Bithynia in response to leech predation have
been published by Bronmark & Malmqvist (1986).
> Taxonomy & Systematics
The calcareous operculum, the food groove, and various reproductive specializations have long been accepted as more than enough warrant to separate Bithynia into its own family of hydrobioids, the Bithyniidae. The specific taxonomy has been stable for many years.
> Supplementary Resources [PDF]
- Bithynia distribution in the Atlantic drainages (2023)
- Virginia species account with county distribution (2011)
> Essays
- Populations of Bithynia in the upper Midwest serve as the intermediate hosts for digenean flukes that have been implicated in massive waterfowl die-offs. See my post to the FWGNA blog of 14Nov07, Ducks, Snails, and Worms - When Invasive Species Conspire! There's also a photo of B. tenticulata on the hoof.
- I reviewed all the Bithynia records in the USGS Nonindigenous Aquatic Species database while researching my post of 16Oct15, "To Only Know Invasives." I didn't find any well-documented populations here in The East previously unknown to me.
> References
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Burch, J. B. (1989) North American Freshwater Snails. Malacological Publications, Hamburg, Michigan, USA.
Bronmark C. & Malmqvist B. (1986) Interactions between the leech Glossiphonia complanata and its gastropod prey. Oecologia 69: 268 - 276.
Clarke, A.H. (1979) Gastropods as indicators of lake trophic stages. Nautilus 93:138-142.
Clarke, A.H. (1981) The Freshwater Mollusks of Canada. National Museums of Canada, Ottawa, Ontario, Canada.
Dillon, R.T., Jr. (2000) The Ecology of Freshwater Molluscs. Cambridge University Press, Cambridge, United Kingdom.
Gilbert, E., Vincent, B. & Rosenberry, L. (1986) Etude experimentale in situ des effets de la densite et de la quantite nourriture chez le gasteropode Bithynia tentaculata (Mollusca: Prosobranchia). Can. J. Zool. 64: 1696-16700.
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Changes in the molluscan community on Oneida Lake, NY, between 1917 and
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Poznańska, M., T. Kakareko, T. Gulanicz, L. Jermacz, and J. Kobak (2015)
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Weeks, A.M., N.R. DeJager, R.J. Haro $ G.J. Sandland (2017) Spatial and temporal relationships between the invasive snail Bithynia tentaculata
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https://doi.org/10.1002/rra.3123
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