Banbury Springs Limpet

Lanx sp.

Description

The Banbury Springs lanx, or limpet, is distinguished with a shell of uniform red cinnamon color, a subcentral apex. This pulmonate snail's length and height exceed its width. Lancids lack either lungs or gills and respire through unusually heavy vascularized mantles, making them highly susceptible to water quality degradation.

Behavior

After reproduction during the late winter-early spring season, older adults will most likely expire. The hermaphroditic reproduction of this species involves the exchange of spermatophores. Courtship entails investigation using tentacles and mouths. Slowly edging closer the snails rear up at right angles to the ground with the bases of their feet in full contact. Supported by the tip of their shells and the hind part of the feet, the male and female open their orifices while caressing each other with their tentacles.

The detritivorous characteristics of this species restricts it to a diet of diatoms and plant debris. The Banbury Springs lanx grazes along mud surfaces, rocky surfaces and macrophytes.

Habitat

The Banbury Springs lanx occupies the Snake River Plains/Sagebrush ecosystem. It is restricted to a few isolated free-flowing reaches or spring alcove habitats of the Snake River. This aquatic system is characterized by cold, well-oxygenated, unpolluted water. The Banbury Springs lanx occurs on stable, cobble-boulder substratum only in flowing waters in the Snake River and also in a few spring alcove habitats in the Hagerman Valley. The species does not burrow in sediments and normally avoids surfaces with attached plants. Known river colonies of the Banbury Springs lanx occur only in areas associated with spring influences or rapids edge environments and tend to flank shorelines. Generally, the species requires cold (15-18°C or 59-64°F) clean, well-oxygenated swift flowing waters on boulder or cobble substratum. The Banbury Springs lanx is found most often on smooth basalt and avoids surfaces with large aquatic macrophytes of filamentous green algae. This species has been collected at depths from 11-30 in (30-75 cm). In a 1992 report the species was found in water as shallow as 2.5 in (5 cm) but this species is most commonly found in depths of 6 in (15 cm).

Distribution

This limpet was first discovered in 1988 at Banbury Springs with a second population found in nearby Box Canyon Springs in 1989. During 1991, a mollusc survey at the Thousand Springs Preserve revealed a third population in Minnie Miller Springs. This species is currently known from Banbury Springs, Box Canyon Springs and Thousand Springs.

Population density for this species was in the range of 4-48 per sq meter on the Thousand Springs Preserve. The total adult population at the Preserve was estimated at between 600-1,200 individuals. These surveys were conducted in the spring alcoves in which the species was originally located. This snail occurs in the least disturbed spring habitats at Banbury Springs, Box Canyon Springs and Thousand Springs.

Threats

The Banbury Springs limpet is only known from three little-disturbed, cool, well-oxygenated, free-flowing springs. Its habitat has been affected by habitat modification and deteriorating water quality associated with hydroelectric development and operation, water withdrawals and diversions, and water pollution. These are also ongoing threats.

Conservation and Recovery

A Recovery Plan was published in 1995 for the Banbury Springs limpet, within the context of the overall ecological recovery of the Snake River. The plan recommends actions to improve water quality and habitat conditions in the Snake River so that viable, naturally reproducing colonies of the limpet can survive. Other measures include protecting occupied habitats, preventing further diversions of water from the Snake River, addressing adequate flow conditions, improving water quality, and enhancing watershed conditions. The populations of the Banbury Springs limpet will also be monitored, and research undertaken into its biology and ecological needs.

Contacts

U. S. Fish and Wildlife Service
Snake River Compensation Plan Office
1387 South Vinnell Way, Room 368,
Boise, Idaho, 83705
Telephone: (208) 378-5321

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

Reference

U.S. Fish and Wildlife Service. 1995. "Snake River Aquatic Species Recovery Plan." Boise, Idaho.