March 14, 2002 (9:53 AM)

Nashville Crayfish

Orconectes shoupi

SPECIES CODE: K01S I01

STATUS: Endangered throughout its range- U.S.A. (TN) (51 FR 34412, September 26, 1986). Recovery Plan completed in 1988 (Nashville Crayfish Recovery Plan).

SPECIES DESCRIPTION: This pigmented crayfish with well-developed eyes ranges from 1/4 to 7 inches in total length. Like many crayfish, this species probably feeds on a variety of organic material, both vegetation fragments and animal matter (USFWS 1988). The crayfish is a good benthic walker and a good swimmer. The Nashville crayfish is most active in the summer. The crayfish’s activity level is low in the winter, but it does move about under ice (Nature Serve Explorer 2002).

REPRODUCTION AND DEVELOPMENT: Reproductive activity begins in spring and egg-laying probably occurs in late winter and early spring (Nature Serve Explorer 2002 and USFWS 1988). Females with eggs and young are found in the spring when they are secluded under large objects (rocks, pieces of metal, and other debris) along the stream banks (USFWS 1988). Females brood eggs below the abdomen. Young are released early in the summer (Nature Serve Explorer 2002).

RANGE AND POPULATION LEVEL: The Nashville crayfish is currently known only from Mill Creek and six of its tributaries in Davidson and Williamson Counties, Tennessee (O’Bara et al. 1985, Bouchard 1984). The crayfish continues to exist in six Mill Creek tributaries: Sevenmile Creek, Sims Branch, Whittemore Branch, Indian Creek, Owl Creek, and Edmonson Branch. All tributary populations except Sevenmile Creek are concentrated near the creek mouths (O’Bara et al. 1985, Bouchard 1984).

HABITAT: The Nashville crayfish has been observed to inhabit pools and riffle areas with moderate current (USFWS 1986). The substrate of the animal’s main habitat, Mill Creek, is mainly bedrock which is covered in some areas with gravel and scattered limestone slabs. The pools, backwater areas, and stream margins are covered with silt and sand. Riverweed (Podostemum sp.) occurs on rocks in some swift water areas, and water willow (Justicia sp.) occurs along some shallow gravel shoals. Much of the stream bank is vegetated with trees and shrubs (Bouchard 1976). The Nashville crayfish has been found in a wide range of environments including gravel and cobble runs, pools with up to 10 centimeters (cm) of settled sediment, and under slabrocks and other cover (the largest crayfish are usually under cover) (USFWS 1988). The species is highly photosensitive and is usually found under cover during the day (Bouchard 1976). Canopy cover appears important, as O’Bara et al. (1985) reported that all sites they sampled had canopy cover of 60 to 90 percent. The species has been found in small pools where the flow was intermittent (Stark 1986, Miller and Hartfield 1985). Gravel-cobble substrate provides good cover for juveniles (Stark 1986, Miller and Hartfield 1985). Females seek out large slabrocks when they are carrying eggs and young. These secluded places are also needed for molting (USFWS 1988).

The animal’s need for clean, high quality water is strongly indicated, despite the fact that it can exist (no data on how long) in polluted‑by‑silt situations (Nature Serve Explorer 2002). The Nashville crayfish requires nonturbid, well‑oxygenated water and clean substrate.

PAST THREATS: The species is threatened by siltation, stream alterations, urban runoff, and general water quality deterioration resulting from development pressures in the urbanized areas surrounding Nashvi1le, Tennessee. The species’ 1imited distribution also makes it vulnerable to a single catastrophic event, such as a toxic chemical spill or other contamination (USFWS 1986). The species is endangered by water quality and other habitat deterioration from development within the watershed. The U.S. Department of the Army, Corps of Engineers (COE) concluded in 1981 that the uppermost segment of Mill Creek was degraded by organic enrichment and had very poor water quality (USFWS 1986).

The Nashville crayfish’s restricted range makes it very vulnerable to a single catastrophic event, such as a chemical spill. COE (1984) reported that occasional spills and discharges have occurred along Mill Creek in the past (USFWS 1986).

CURRENT THREATS: The Nashville crayfish is endangered by water quality deterioration from development within the watershed. The Nashville crayfish’s restricted range makes it very vulnerable to a single catastrophic event such as a chemical spill (USFWS 1988).

Much of the Mill Creek system is within the Nashville City limits and water quality degradation in this area does not appear to have reduced the range of the Nashville crayfish.

Threats to the species could also come from other activities in the watershed such as road and bridge construction, stream channel modifications, impoundments, land use changes and other projects, if such activities are not planned and implemented with the survival of this geographically restricted species in mind (USFWS 1986).

Crayfish are frequently taken in the southeastern United States for food or bait. Overutilization for these purposes could become a problem if the species’ specific habitat were identified to the extent required for designation of critical habitat (USFWS 1986).

CONSERVATION MEASURES:

LITERATURE CITED:

Bouchard, R.W. 1976. Investigations on the status of fourteen species of freshwater decapod crustaceans in the United States, Part I. Troglobitic shrimp and western North American crayfishes. Report to Office of Endangered Species, Department of the Interior. 26 pp.

Bouchard, R.W. 1984. Distribution and status of the endangered crayfish Orconectes shoupi (Decapoda: Cambaridae). U.S. Fish and Wildlife Service, Tennessee Cooperative Fishery Research Unit, Tennessee Tech University, Cookeville, Tennessee. 27 pp.

Miller, A. C. and P. D. Hartfield. 1985. A study of Orconectes shoupi, Mill Creek Basin, Tennessee, 1985. U.S. Army Corps of Engineers, Nashville, TN. 25 pp.

Miller, A.C., P.D. Hartfield, L. Rhodes. 1990. An investigation of Orconectes shoupi in Mill and Seven Mile creeks, Tennessee. Journal of the Tennessee Academy of Science 65(1):21‑24.

Nature Serve Explorer. An online encyclopedia of life [web application]. 2001. Version 1.6. Arlington, Virginia, USA: Nature Serve. Available: http://www.natureserve.org/explorer (Accessed: March 13, 2002).

O’Bara, C. J., A. J. Korgi, and G. J. Stark. 1985. Final report, status survey of the Nashville crayfish (Orconectes shoupi). Report to U.S. Fish and Wildlife Service, Asheville, NC. 17 pp.

Stark, G. J. 1986. Microhabitat use by the crayfish community of the Mill Creek Basin. Thesis, Tennessee Technological University, Cookeville, TN. 44 pp.

Tennessee Department of Public Health. 1978. Mill Creek survey, Davidson County, Tennessee. Division of Water Quality Control, Nashville Basin. Unpublished report. 7 pp.

U.S. Army Corps of Engineers, Nashville District. 1981. Water quality along Mill Creek. Nashville, Tennessee. 35 pp.

U.S. Army Corps of Engineers, Nashville District. 1984. Mill Creek, Wimpole Drive area, Nashville, Davidson County, Tennessee. Final detailed project report and environmental assessment. 331 pp.

U.S. Fish and Wildlife Service. 1986. Endangered and threatened wildlife and plants; determination of endangered status for the Nashville crayfish. 51 Federal Register 34412.

U.S. Fish and Wildlife Service. 1988. Nashville crayfish Recovery Plan (1st revision). U.S. Fish and Wildlife Service, Atlanta, Georgia. 16 pp.