CUMBERLAND MONKEYFACE (PEARLYMUSSEL)

Quadrula intermedia

SPECIES CODE: F00E I01

STATUS:

On June 14, 1976, the Cumberland monkeyface (pearlymussel) was designated as endangered throughout its entire range in Alabama, Tennessee, and Virginia (USFWS 1976), except where listed as experimental populations (in the free‑flowing reach of the Tennessee River below the Wilson Dam, Colbert and Lauderdale Counties, AL) (USFWS 2001). A recovery plan addressing the Cumberland monkeyface was approved in 1984 (USFWS 1984).

SPECIES DESCRIPTION:

The Cumberland monkeyface is a medium-sized freshwater mussel (reaching up to 80 mm in length) with a yellow-green shell characterized by numerous green spots, chevrons, or zig-zag patterns and is similar in appearance to the Appalachian monkeyface pearlymussel (Quadrula sparsa) (VFWIS 2003). Like other freshwater mussels, the Cumberland monkeyface feeds by filtering food particles from the water column. The specific food habits of the species are unknown, but other juvenile and adult freshwater mussels have been documented to feed on detritus, diatoms, phytoplankton, and zooplankton (Churchill and Lewis 1924). The diet of Cumberland monkeyface glochidia, like other freshwater mussels, comprises water (until encysted on a fish host) and fish body fluids (once encysted).

REPRODUCTION AND DEVELOPMENT:

The reproductive cycle of the Cumberland monkeyface is similar to that of other native freshwater mussels. Males release sperm into the water column; the sperm are then taken in by the females through their siphons during feeding and respiration. The females retain the fertilized eggs in their gills until the larvae (glochidia) fully develop. The mussel glochidia are released into the water, and within a few days they must attach to the appropriate species of fish, which they parasitize for a short time while they develop into juvenile mussels. They then detach from their fish host and sink to the stream bottom or other substrate where they continue to develop, provided they land in a suitable substratum with the correct water conditions. Adult mussels of this species are sexually dimorphic. Recent studies have identified two cyprinids, the streamline chub (Erimystax dissimilis) and blotched chub (Erimystax insignis) as glochidial host species for the Cumberland monkeyface. Both fish hosts are known to occupy similar riffle habitats as the mussel (Yeager and Saylor, 1995).

RANGE AND POPULATION LEVEL:

The Cumberland monkeyface was historically known from 11 rivers in the Tennessee River system (USFWS 1984). It was last collected from Mussel Shoals, an 85 km reach of the Tennessee River in Alabama, around 1900 (Ortmann 1925) and is presumed to be extirpated from the shoal. Currently, the species survives only at a few shoals in the Powell River in Tennessee and Virginia and the Elk and Duck Rivers in Tennessee (USFWS 1984). Since 1970, the Cumberland monkeyface has also been found in the Clinch, Powell, and Tellico Rivers (NatureServe 2003). The extant population in the Duck River in Tennessee was confirmed in August 1997 when two individuals were found (NatureServe 2003).

HABITAT:

The Cumberland monkeyface typically occurs in shallow shoal and riffle areas in free-flowing streams of high to moderate gradient. Substrate preferences include firm rubble, gravel and sand and the species most often remains buried with only siphons visible (USFWS 1984, ESIS 1996, VFWIS 2003). The Cumberland monkeyface has been found in waters ranging from six inches to two feet in depth (Bogan and Parmalee 1983). The species has never been found in small streams (VFWIS 2003). The habitat preference of this species is similar to that of the closely related Appalachian monkeyface (ESIS 1996).

PAST THREATS:

Many of the historic populations of the Cumberland monkeyface were apparently lost when the upper Tennessee River drainage was impacted by dam construction, channelization, siltation and water pollution (USFWS 1984). The Powell River and upper tributaries of the Clinch River, in particular, are also subject to sediment and particulate matter loading from coal mining activities (Stansbery 1973). Other threats that are attributed to population declines are similar to those described in the general mussel description.

CURRENT THREATS:

In addition to the factors listed above, current threats include the low gene pool for remaining populations, collection, invasion of the Asiatic clam (Corbicula fluminea), and the Columbia Dam project on the Duck River in Tennessee. Other current threats to freshwater mussels are well documented in the general mussel description.

CONSERVATION MEASURES:

Exposure Scenario Summary Table for the Cumberland monkeyface
Species	Life Stage	Habitat Type	Exposure Route	Diet	Significant Interspecies Relationships
Cumberland monkeyface	glochidia	parasite	contact with water, diet	water (until encysted), fish body fluids (once encysted)	streamline chub blotched chub
	juvenile / adult	sediment dweller	contact & ingestion of water, diet, sediment	filter feeder (bacteria, algae, detritus, sediment)

LITERATURE CITED:

Bogan, A.E. and P.W. Parmalee. 1983. Tennessee's rare wildlife. Vol. 2: The mollusks. Tennessee Wildlife Resources Agency and the Tennessee Conservation Department. 123 pp.

Churchill, E.P., Jr., and S.I. Lewis. 1924. Food and feeding in freshwater mussels. Bull. U.S. Bur. Fish. 39: 439-471.

Endangered Species Information Exchange. 1996. Species Id ESIS404012. Virginia Tech Fish and Wildlife Information Exchange. Available http://fwie.fw.vt.edu/WWW/esis/lists/e404012.htm. (Accessed: December 2, 2003)

NatureServe. 2003. NatureServe Explorer: An online encyclopedia of life [web application]. Version 1.8. NatureServe, Arlington, Virginia. Available http://www.natureserve.org/explorer. (Accessed: December 2, 2003 ).

Ortmann, A.E. 1925. The naiad fauna of the Tennessee River system below Walden Gorge. The American Midland Naturalist. 9(8): 321-372.

Stansbery, D.H. 1973. A preliminary report on the naiad fauna of the Clinch River in the southern Appalachian Mountains of Virginia and Tennessee (Mollusca: Bivalvia: Unionidae). Bull. Am. Malacol. Soc. 1972: 20-22.

U.S. Fish and Wildlife Service. 1976. Endangered Status for 159 Taxa of Animals. Federal Register 41: 24062-24067.

U.S. Fish and Wildlife Service. 1984. Recovery plan for the Cumberland monkeyface pearly mussel, Quadrula intermedia (Conrad, 1836). U.S. Fish and Wildlife Service, Region 4. Atlanta, GA.

U.S. Fish and Wildlife Service. 2001. Endangered and Threatened Wildlife and Plants; Establishment of Nonessential Experimental Population Status for 16 Freshwater Mussels and 1 Freshwater Snail (Anthony's Riversnail) in the Free‑Flowing Reach of the Tennessee River below the Wilson Dam, Colbert and Lauderdale Counties, AL. Federal Register 66(115): 32250-32264.

Virginia Fish and Wildlife Information Service. 060123 Monkeyface (pearlymussel), Cumberland. Virginia Department of Game and Inland Fisheries. Available http://vafwis.org/BOVA/BOOKS/060123.HTM. (Accessed: December 2, 2003).

Yeager, B.L. and C.F. Saylor. 1995. Fish hosts for four species of freshwater mussels (Pelecypoda: Unionidae) in the upper Tennessee River drainage. American Midland Naturalist. 133(1): 1-7.