It is perhaps not surprising that the freshwater gastropod
fauna of the state is so poorly known. Although some of the
major rivers in the western half of the state have received adequate
attention (e.g., Clench & Turner 1956), all the freshwater
gastropod surveys conducted in Georgia Atlantic drainages have been
limited and local, prior to the present report.
Previous workers in eastern or central Georgia have focused almost entirely on selected prosobranch families - the Viviparidae (Call 1894, Goodrich 1942a, Clench 1962), the Pleuroceridae (Goodrich 1942b, Mihalcik & Thompson 2002), or the Hydrobiidae (Thompson 1969, 1977, Watson 2000). Goodrich (1939) reported the results of a general survey conducted by Henry van der Schalie on the Ogeechee River, listing Valvata bicarinata, Ferrissia rivularis, Pleurocera (formerly Goniobasis) catenaria, and various species in the genera Campeloma, Amnicola, Somatogyrus, Physa, and Helisoma. Thompson & Hershler (1991), although focusing primarily on the hydrobiids, offered some general observations on the biogeography of the entire freshwater gastropod fauna of Georgia. They described an area virtually "devoid of freshwater snails" in the Suwannee, St. Marys, and Satilla Rivers of the state's southern quarter. More recently, Sukkestad et al. (2006) have reported seven freshwater gastropod taxa inhabiting the Fort Stewart Army Installation of northern coastal Georgia - Valvata bicarinata, Campeloma decisum, Marstonia halcyon, Pleurocera catenaria, Physa acuta, Helisoma trivolvis, Laevapex fuscus, and Ferrissia sp.
In the ecological literature, populations of both Pleurocera catenaria and "Ferrissia sp" (presumably F. fragilis) were involved in a study published by Nelson & Scott (1962) on food web dynamics in the Middle Oconee River. Krieger and Burbanck (1976) described microhabitat distribution and movement patterns of Pleurocera catenaria (under the alias "Goniobasis suturalis") inhabiting the Yellow River, a tributary of the Ocmulgee. They related environmental features to P. catenaria distribution for purposes of identifying factors limiting local variation in abundance.
The present survey focuses on the gastropod fauna of the Atlantic drainages only. The gastropod fauna of Tennessee River tributaries draining portions of 7 counties at the northern margin of the state is covered by the FWGTN survey elsewhere on this site. Our long term plans include an extension of coverage to include tributaries flowing south through Florida and Alabama to the Gulf of Mexico, as resources permit.
The database here analyzed includes 875 records from two primary
sources. The largest fraction come from museum collections,
primarily the Florida Museum
of Natural History in Gainesville, with smaller contributions from the
Georgia Museum of Natural History in Athens, the North Carolina State
Museum in Raleigh, the US National Museum, and the Academy of Natural
Sciences of Philadelphia. We queried online
databases as available to extract freshwater gastropod records
from the 86 Georgia
counties draining into the Atlantic, deleted brackish-water records,
and inspected the remainder to eliminate any Gulf drainage records from
counties on the margins. We also deleted records collected
prior to 1955 or those with no date, as well as duplicate records
(usually differing only by date). We then traveled to the
locations of the five museums to verify identifications and
examine problematic lots.
The remainder of the records (approximately 300) are from our own original collections, made 2003-15 using simple untimed searches (Dillon 2006). Ultimately our survey covered approximately 250 discrete sample sites, located throughout the Atlantic drainages of Georgia, in all ecoregions, all subdrainages, and all counties. A map (in PDF format) showing the distribution of these sites is available as Figure 1. No “absence stations” are shown. If freshwater gastropods were not collected at a site, then no record resulted. Our entire 869 record database is available (as an excel spreadsheet) from the senior author upon request.
The taxonomy employed by the FWGNA project is painstakingly researched, well-reasoned and insightful. Needless to say, it often differs strikingly from the gastropod taxonomy in common currency among casual users and natural resource agencies. First-time visitors looking for information about particular species or genera might profitably begin their searches with a check for synonyms in our alphabetical index.
We thank John Robinson and Tom Smith for their help with the field work. Gracious hosts included John Slapcinsky and Fred Thompson at the Florida Museum of Natural History, Liz McGhee at the Georgia Museum of Natural History, Art Bogan and Jamie Smith at the North Carolina State Museum, Bob Hershler and Jerry Harasewych at the USNM, and Gary Rosenberg, Paul Callomon, and Amanda Lawless at the Academy of Natural Sciences of Philadelphia. The early success of this project in large part depended on the GIS and data analysis skills of Dr. Doug Florian, and continues to depend on the webmastery of Mr. Steve Bleezarde.
Call, R.E. 1894. On
the geographic and hypsometric distribution of North American
Viviparidae. Amer. J. Science 48:132-140.
Clench, W.J. & R.D. Turner. 1956. Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwannee River. Bull. Fl. State Mus., Biol. Sci. 1:95-239.
Clench, W.J. 1962. A catalogue of the Viviparidae of North America with notes on the distribution of Viviparus georgianus Lea. Occas. Pprs. Mollusks 2:261-285.
Dillon, R.T., Jr. 2006. Freshwater Gastropoda. pp 251 - 259 In The Mollusks, A Guide to their Study, Collection, and Preservation. Sturm, Pearce, & Valdes (eds.) American Malacological Society, Los Angeles & Pittsburgh.Goodrich, C. 1939. Certain mollusks of the Ogeechee River, Georgia. Nautilus 52:129-131.
Goodrich, C. 1942a. The American species of Viviparus. Nautilus 55:82-92.
Goodrich, C. 1942b. The Pleuroceridae of the Atlantic Coastal Plain. Occas. Pprs. Mus. Zool. Univ. Mich. 456:1-6.
Krieger, K.A. & W.D. Burbanck. 1976. Distribution and dispersal mechanisms of Oxytrema (= Goniobasis) suturalis Haldeman (Gastropoda: Pleuroceridae) in the Yellow River, Georgia, U.S.A. Amer. Midl. Natur. 95:49-63.
Mihalcik, E. L. & F. G. Thompson 2002. A taxonomic revision of the freshwater snails referred to as Elimia curvicostata, and related species. Walkerana 13: 1 - 108.
Nelson, D.J. & D.C. Scott. 1962. Role of detritus in the productivity of a rock-outcrop community in a piedmont stream. Limnol. Oceanog. 7:396-413.
Sukkestad, K.E., E.P. Keferl, E.P. & T.D. Bryce. 2006. Freshwater mollusks of Fort Stewart, Georgia, U.S.A. Amer. Malac. Bull. 21:31-38.
Thompson, F.G. 1969. Some hydrobiid snails from Georgia and Florida. Quarterly J. Fl. Acad. Sci. 32:241-265.
Thompson, F.G. 1977. The hydrobiid snail genus Marstonia. Bull. Fl. State Mus. 21:113-158.
Thompson, F.G. & R.H. Hershler. 1991. Two new hydrobiid snails (Amnicolinae) from Florida and Georgia, with a discussion of the biogeography of freshwater gastropods of South Georgia streams. Malac. Rev. 24:55-72.
Watson, C. 2000. Results of a survey for selected Hydrobiidae (Gastropoda) in Georgia and Florida. Proc. First Freshwat. Moll. Conserv. Soc. Sympos. 233 - 244.