|Listed||June 14, 1976|
|Family||Unionidae (Freshwater Mussel)|
|Description||Freshwater mussel with medium-sized, yellow-green or brown quadrangular shell with distinctive markings.|
|Habitat||Fast-flowing water in shallow shoals.|
|Reproduction||Breeds from May to July.|
|Threats||Impoundments, siltation, pollution.|
The yellow-green or brown shell of the Appalachian monkeyface pearlymussel (Quadrula sparsa ) is medium-sized (2.8 in [7 cm]) and nearly quadrangular in shape. The shell surface is marked with small green zig-zags, triangles, or chevrons and strong, concentric growth rings.
This mussel is thought to breed from May to July. Its fish hosts are unknown. For more on the reproduction and diet of freshwater mussels, see the Upland Combshell (Epioblasma metastriata ) entry.
This freshwater Cumberlandian mussel is found most often in clean, shallow river stretches where the bottom is composed of relatively firm rubble, gravel, and sand. Swift currents in these shoals typically sweep the bottom free of silt.
This species was first collected in 1841 from the Holston River in eastern Tennessee and is thought to have been widespread in tributaries of the upper Tennessee and Cumberland river systems.
The Appalachian monkeyface was apparently never abundant, and the reasons for its decline are not fully understood, but impoundments, siltation, and pollution are presumed to be the major causes. The Norris Dam, in particular, probably inundated this mussel's habitat shoals in both the Powell and Clinch Rivers. The cold tailwaters have made long upstream portions of the rivers uninhabitable for both mussels and host fishes.
Siltation caused by strip mining, coal washing, and poor agricultural practices have buried gravel and sand shoals and smothered mussel beds. Because mussels must siphon gallons of water each day to feed, the effects of water pollutants such as herbicides and pesticides are intensified.
Surveys conducted by the Tennessee Valley Authority (TVA) in 1988 and 1989 suggest that mussel populations in the Clinch River continue to decline. The status of populations in the Powell River has not yet been determined. Recovery for this mussel will require rehabilitation of at least part of its historic habitat to allow populations to be reestablished.
Conservation and Recovery
The TVA, which administers the operation of dams on the Tennessee and Cumberland Rivers, is working on water management to guarantee constant minimum flows in all rivers in the Tennessee and Cumberland basins by timing water discharges from its dams. Such an effort may lessen many of the negative effects of dams and reservoirs on remaining stretches of mussel habitat.
U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Bogan, A., and P. Parmalee. 1983. "Tennessee's Rare Mollusks." In Tennessee's Rare Wildlife, Final Report. Department of Conservation and Tennessee Heritage Project, University of Tennessee, Knoxville.
Branson, B. A. 1974. "Stripping the Appalachians."Natural History 83, (9): 53-60.
French, John R. P., III. November 1990. "The Exotic Zebra Mussel: A New Threat to Endangered Freshwater Mussels." Endangered Species Technical Bulletin 15 (11).
Fuller, S. 1974. "Clams and Mussels (Mollusca: Bivalvia)." In Pollution Ecology of Freshwater Invertebrates. Academic Press, New York.
Neel, J. K., and W. R. Allen. 1964. "The Mussel Fauna of the Upper Cumberland Basin before Its Impoundment." Malacologia 1 (3): 427-459.
Pardue, J. W. 1981. "A Survey of the Mussels (Unionidae) of the Upper Tennessee River, 1978." Sterkiana 71: 41-51.
U. S. Fish and Wildlife Service. 1983. "Appalachian Monkeyface Recovery Plan." U. S. Fish and Wildlife Service, Atlanta.