Flattened Musk Turtle

Sternotherus depressus

Description

The flattened musk turtle, Sternotherus depressus, is an aquatic turtle with a distinctly flattened carapace (upper shell), about 5 in (12.7 cm) long when fully grown. The carapace is dark brown to orange with dark bordered seams and a slightly serrated back edge. The undershell (plastron) is pink to yellowish. The head is greenish with narrow stripes on the top and neck. The chin has two sensors (called barbels), and all four feet are webbed. Males have thick, long, spine-tipped tails.

Behavior

This turtle feeds primarily on freshwater mollusks. Males mature in four to six years, females in six to eight. Females deposit one or two clutches of eggs each season with an average of three eggs per clutch.

Habitat

Although the flattened musk turtle is found in a variety of streams and in the headwaters of some dammed lakes, its optimum habitat appears to be free-flowing large creeks or small rivers with vegetated shallows, alternating with deeper, rock-bottomed pools.

Distribution

The flattened musk turtle was once found in the upper Black Warrior River system of Alabama, upstream from Tuscaloosa, which is on the fall line between the Piedmont Plateau and the coastal plain. Since 1930, several dams have been built on the river and near the fall line. The resulting reservoirs were more favorable for another turtle, Sternotherus minor peltifer. Where the ranges of the two turtles overlapped, interbreeding occurred to the detriment of the flattened musk turtle population.

Genetically pure populations of this turtle are now believed to exist only in the Black Warrior River system, upstream from Bankhead Dam in Blount, Cullman, Etowah, Jefferson, Lawrence, Marshall, Tuscaloosa, Walker, and Winston Counties of north-central Alabama.

Threats

Collecting of the flattened musk turtle has reduced the overall population. Some dealers brazenly advertise the turtle for sale at high prices. The turtle's new status as an endangered species should provide protection from collection and sale.

Clay siltation in the river system also may have had a great impact on the population size. Silting has been caused by a combination of forest clear-cuts, agricultural run-off, and mining operations. The upper basin region is underlain by the Black Warrior and Plateau Coal Fields. New regulations have recently reduced the rate of new sediment being washed into the river system. Past deposits, however, continue to affect the quality of the habitat, and recovery will be slow.

Conservation and Recovery

The U. S. Fish and Wildlife Service published a Recovery Plan for the flattened musk turtle in 1990. One of the key actions required for its conservation is the strict protection from illegal collection by amateurs and for sale in the pet trade. Its habitat must also be protected from siltation and other kinds of pollution. A goal of the Recovery Plan is to achieve at least 12 sustainable populations of the rare turtle. In cases where critical habitat is privately owned, it should be protected by acquisition and designation of an ecological reserve, or by negotiation of conservation easements with the owners. The populations of the flattened musk turtle should be monitored, and research undertaken into its biology and habitat needs. Work should be undertaken into captive breeding, with the goal of providing stock for release to supplement small wild populations or to establish new ones.

Contact

Regional Office of Endangered Species
U. S. Fish and Wildlife Service
1875 Century Blvd, Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

References

Ernst, C. H., and R. W. Barbour. 1972. Turtles of the United States. University Press of Kentucky, Lexington.

Tinkle, D. W., and R. G. Webb. 1955. "A New Species of Sternotherus with a Discussion of the Sternotherus carinatus Complex." Tulane Studies in Zoology 3: 52-67.

U. S. Fish and Wildlife Service. 1990. Flattened Musk Turtle Recovery Plan. Jackson, Mississippi.