SPECIES FACT SHEET Species Common Name: Nerite Rams-horn Species Scientific Name: Vorticifex neritoides, Baker 1945 Phylum: Mollusca Class: Gastropoda Order Basommatophora Family: Planorbidae Type Locality: “Lower Columbia River” probably at the Dalles, Wasco Co., OR (Frest and Johannes 1995). Type locality considered extirpated. OR/WA BLM and FS Region 6 Units where Suspected or Documented: Columbia River Gorge National Scenic Area (suspected). Technical Description: Shell similar to that of V. effusa, but smaller, with a lower spire, few whorls and comparatively thicker shell. Life History: Semelparous – lives 1-2 years, breeds and dies. Population turn over is probably greater than 90%. Freshwater pulmontates generally reproduce by copulation and crossfertilization. Eggs are laid from spring to autumn in gelatinous capsules attached to plants, stones, or other objects. They lack a free-swimming larval stage, and hatch as young snails, anatomically complete except for the reproductive system (Hyman 1967). Feed by scraping algae and diatoms from rock surfaces in stream. May occasionally feed on other plant surfaces. Present all year, but not active in winter. Individuals have no lungs or gills with respiration through the mantle cavity. Range, Distribution (Current and Historic), and Abundance: Formerly occurred from the Dalles to the mouth of the Columbia River (Frest and Johannes 1995). Frest and Johannes (1995) also report that this species could not be relocated at the “type locality” at the Dalles in 1988, and only one new location on the north side of the Columbia was found during surveys at this time. The lower Columbia River populations, including the type location, are largely extirpated due to habitat modification caused by BPA dams and impoundments although 1 one occurrence is known from the north side of the river. No specific information on abundance found. Habitat Associations: Since this species is so rarely found, habitat associations given here are general. Generally found in relatively deep rivers, in unpolluted, swiftflowing, highly oxygenated water on stable (boulder-gravel) substrate, such as in the vicinity of rapids or other unimpounded stretches. Threats: Hydropower development on the Columbia River has destroyed much of this species former habitat. Also, irrigation diversions, siltation and fluctuations in dissolved oxygen caused by pollution have also contributed. Frest and Johannes (1995) report the following threats: impoundment and damming of much of the original habitat; sedimentation; orchard runoff; nutrient enrichment due to agricultural practices, pulp mill effluents; metal smelting residues and discharges. Conservation Considerations: (1) Control siltation and pollution, (2) prevent fluctuations in dissolved oxygen. Prepared by: Nancy Duncan, April 2008 Edited by Rob Huff, April 2009 References Baker, F. C. 1945. The Molluscan Family Planorbidae. University of Illinois Press, Urbana, Illinois, 530 pp. Burch, J. B. 1982. Freshwater snails (mollusca: gastropoda) of North America. Environmental Monitoring and Support Laboratory. U.S. Environmental Protection Agency. Contract No. 68-03-1280. Cincinnati, Ohio. Frest, T. J., and E. J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-49112. 274 pp. plus appendices. Hyman, L. L. 1967. The invertebrates. Vol VI. Mollusca I. McGrawHill, New York. 792 pp. 2 USDA/USDI. 1994. Final supplemental environmental impact statement on management of habitat for old-growth forest related species within the range of the Northern Spotted Owl: Appendix J2 results of additional species analysis. Portland, Oregon 3