In North America, 92% of the freshwater snails in the family Hydrobiidae (Pyrg Pebblesnails) are imperiled (Johnson et al., 2013).
It is unclear whether this small snail remains an extant member of New York's Gastropod fauna since the last verfied records were from about 70 years ago (1940s). Since then, one statewide snail survey, and another in central New York, did not turn it up. Further, this species is a habitat specialist that depends on highly stable groundwater conditions in forests, both of which have been highly degraded in the heavily agricultural and urbanized far western region of the state. The rank of S1S3 might need to be revised pending any further survey work in far western NY.
The Watercress snail was not detected in the two most recent snail surveys in New York (Jokinen 1992; Harman and Berg 1971). Little or no effort has been expended in the state to look for this species (or most other freshwater Gastropods) in recent decades.
Older records from the late 1800s were from seemingly unsuitable habitats (i.e., canals), including one from the Hudson watershed in Westchester County which was likely mis-identifed because the reported habitat was unsuitable (lentic) and the specimen record no longer exists at the holding museum, suggesting is was re-classified. The last documented records for this snail were in far western New York in the 1940s, when well over 50 specimens were collected from at least four separate springs (Robertson and Blakeslee 1948).
Population densities become rapidly attenuated downstream from a spring's underground emergence, suggesting that constant cold temperatures are vital to this snail Dillon et al., 2006). Thus, forest removal and other activities that effect the groundwater table could have negative consequences for population viability. A recent assessment of freshwater Gastropods in North America revealed that 74% of the species are imperiled or already extinct and they have the highest modern extinction rate yet recorded-- almost 10,000 times background rates. The top threats to the group as a whole are: highly restricted ranges (narrow endemics), habitat destruction (hydrological aleration= dams/channelization), and water pollution (Johnson et al., 2013).
Since Watercress (Nasturtium officinale) is an exotic invasive plant of European origin, only becoming a member of our flora since the early 1900s, it is unclear what native aquatic macrophytes F. nickliniana might have previously been associated with.
Forested spring runs, especially those having thick mats of Watercress in Niagara and Erie Counties, should be inventoried to ascertain whether this species is still an extant member of New York's Gastropod fauna.
These snails can be found in a variety of habitats ranging from small lakes to springs and spring-fed streams to a few caves (Hershler et al., 1990). However, they are primarily confined to calcium rich, cold hardwater shallow slowly flowing forested springs associated with lush beds of watercress where they reach their maximum abundance. The snails live on and among the watercress, feeding on diatoms.
This species may still occur in a handful of localities in extreme western Erie and Niagara Counties.
The range of this freshwater snail is highly disjunct. There is a Great Lakes segment, primarily in western Michigan, northwestern Indiana and adjacent Illinois and eastern Wisconsin. The Appalachian segment runs from central Alabama to central Pennsylvania, with a possible extension into far western New York. These two distinct distributions might be the modern expression of separate glacial refugia as it is for many other species with similar disjunct distributions in the eastern U.S.
This is a small snail with a 3.5-4.5 mm long, narrowly conic, shiny black shell with 4.5-7.5 well-rounded whorls and deep sutures where the whorls border one another. The operculum is roundly ovate with 4-5 rapidly enlarging spirlas and is about 1.0 mm in width.
This is a moderate to large-sized species (within Fontigens) with an elongate conic shell. It is most similar to Fontigens aldrichi, but this species does not occur in New York.
The elongate conic shell is distinctive.
This species may become introduced into new sites with Watercress. Snails of this family typically lay eggs singly on hard substrates, including the shells of other Gastropods (Johnson et al., 2013). Lifespan is in the range of 2-5 years.
This snail gleans diatoms from the surface of Watercress (Nasturtium officinale) plants.
Activity levels are unknown, but older museum specimens from Erie County were collected in February. Populations typically maintain high densities year-round, suggesting continuous reproduction (Dillon et al., 2006).
The time of year you would expect to find Watercress Snail present and active in New York.
Fontigens nickliniana (I. Lea, 1838)
Harman, W. N., and C. O. Berg. 1971. The freshwater snails of central New York with illustrated keys to the genera and species. Cornell University Agricultural Experiment Station in Entomology. Ithaca, NY.
Berry, E.G. 1943. The Amnicolidae of Michigan: distribution, ecology, and taxonomy. Miscellaneous Publications of the Museum of Zoology, University of Michigan, 57: 1-68.
Biggs, J., M. Walton, and T. Sternbach. 2011. Survivability of Watercress Snails in springs of central Pennsylvania. Journal of Ecological Research 13:44-47.
Dillon, R.T., Jr., B.T. Watson, and T.W. Stewart. 2006a. The freshwater gastropods of North Carolina. Created 26 August 2003 by Rob Dillon, College of Charleston, Charleston, South Carolina. Available online: http://www.cofc.edu/~fwgna/FWGNC/index.html. Last updated September 2007.
Evans, R.R. and S.J. Ray. 2010. Distribution and environmental influences on freshwater gastropods from lotic systems and springs in Pennsylvania, USA, with conservation recommendations. American Malacological Bulletin 28:135-150.
Hershler, R., J.R. Holsinger, and L. Hubricht. 1990. A revision of the North American freshwater snail genus Fontigens (Prosobranchia: Hydrobiidae). Smithsonian Contributions to Zoology, 509: 1-50.
Johnson, P.D. et al., 2013. Conservation status of freshwater Gastropods of Canada and the United States. Fisheries 38:247-282.
Jokinen, E.H. 1992. The Freshwater Snails (Mollusca: Gastropoda) of New York State. New York State Museum, Bulletin, 482: 1-112.
New York Natural Heritage Program. 2019. New York Natural Heritage Program Databases. Albany, NY.
Robertson, I. and C. Blakeslee. 1948. The mollusca of the Niagara Frontier region. Bulletin Buffalo Society Natural Science 19: 1-191.
This guide was authored by: Jeffrey D. Corser
Information for this guide was last updated on: March 29, 2016
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Fontigens nickliniana. Available from: https://guides.nynhp.org/watercress-snail/. Accessed January 18, 2019.