Slender Campeloma

Campeloma decampi

Description

The shell of the slender campeloma is medium to large, usually less than 1.4 in (35 mm) in length, narrow, relatively thin, and generally with prominently raised spiral lines. Lateral and marginal teeth of the shell are simple with very fine, difficult to distinguish points. The shell has no spiral nodules, spiral color bands or exaggerated angle of the opening to the outer margin of the shell.

The plate that closes the shell when the campeloma retracts is entirely concentric and does not reflect inward at the center.

Sexes are separate in this family, and males are distinguished by their modified right tentacle that serves as a copulatory organ. This tentacle is shorter and thicker than the left tentacle and the bilaterally symmetrical female tentacles.

The slender campeloma is distinquished from the closely related Campeloma decisum by the presence of faint striations and a relatively higher spire on the shell. The shell of the slender campeloma also tends to have strongly developed ridges, and ridges in the juveniles and early whorls of adults tend to be carinate (keel-shaped).

Behavior

The life history of the slender campeloma has not been studied by biologists, but many conclusions to their behaviors can be drawn by comparing this species to others in the genus and family.

All members of this family give birth to live young, rather than laying eggs like many other snails. Studies of the Campeloma genus show that May is the peak season for births, although the birthing season reaches into the beginning of September. They also carry young in the uterus over winter.

Habitat

The slender campeloma is often found burrowing in soft sediments or detritus, which is its main source of food. Detritus is made up of organic matter and rock fragments.

Historically, specimens have been found on stream impoundments.

Distribution

The historic range of the slender campeloma has been reduced by at least three-quarters. Habitat was once found along the north side of the Tennessee River in Jackson, Limestone, Madison, and Morgan Counties in Alabama.

Of the past populations, one was inundated by Wheeler Reservoir, and others cannot be found or reached.

Current population distribution is spotty. Existing populations are now isolated by Wheeler Reservoir, restricted to a few isolated sites along Round Island, Piney, and Limestone Creeks, three short stream reaches in Limestone County. Limestone Creek contains many listed species, indicating that this system has been severely impacted and undergone significant degradation.

Threats

Due to small population sizes and limited occupied habitat, the slender campeloma is extremely vulnerable. Threats include direct loss of habitat, siltation, altered water chemistry and chemical pollution.

The placement of Wheeler Reservoir has greatly impacted habitat for the slender campeloma. Dams and their impounded water can form barriers to snail movement, promote siltation and encourage changes in the flow of water and water chemistry. This reduces food and oxygen availability, affecting reproductive success and altering habitat.

In addition, when local water and habitat quality change, many isolated snail populations become more vulnerable to run-off and discharges into the watershed.

Additional sources of siltation include channel modification, agriculture, cattle grazing, logging, chip mills, unpaved road drainage, rock quarries, bridges and road expansion projects and industrial and residential development.

Discharges from polluting sources increase eutrophication, decrease dissolved oxygen concentration, increase acidity and conductivity, and create other changes in water chemistry. Some sources include leach from agricultural fields (especially cotton), residential lawns, livestock operations and leaking septic tanks which also contribute to changes in water quality.

Conservation and Recovery

Current conservation measures include the certain designation of critical habitat and a review of all projects affecting habitat. The Federal government is not requesting information about projects specifically affecting the habitat of the slender campeloma due to the listing of the armored snail which has a very similar range. After projects are reviewed appropriate conservation measures will be taken.

The U. S. Fish and Wildlife Service has determined that dams and their impoundments prevent the natural recolonization of surviving snail populations. Even if watershed impacts improve or even disappear, the damage will continue as long as the dams are present.

Contacts

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

Asheville Field Office
U. S. Fish and Wildlife Service
160 Zillicoa Street
Asheville, North Carolina 28801-1082
Telephone: (828) 258-3939
Fax: (828) 258-5330

Reference

United States Department of the Interior. 25 February 2000. "Endangered and Threatened Wildlife and Plants: Endangered Status for the Armored Snail and Slender Campeloma." Federal Register 65 (38):10033-10039.