Kanab ambersnail
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 A Kanab ambersnail at Vaseys Paradise in Grand Canyon National Park.
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| Oxyloma haydeni kanabensis (Pilsbry, 1948)[2] |
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 Habitat of the Kanab ambersnail
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The Kanab ambersnail (Oxyloma haydeni kanabensis) is a critically endangered subspecies of snail restricted to wetlands, springs, and seeps.[3] Only two natural habitats of the snail are known to exist, both located in the United States: Three Lakes, a meadow near Kanab, Utah, and Vaseys Paradise, a spring along the Colorado River within Grand Canyon National Park.[3] In addition to its natural populations, the Kanab ambersnail has been introduced to three springs above the historic high water level along the Colorado River. The family of land snails gets its common name, amber snail, from the snails' characteristic orange colored shell.[4]
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[edit] History
The snail was first collected in 1909 by James Ferriss, who placed them in the Succinea genus. Their current trinomial description and placement as a subspecies comes from Henry Augustus Pilsbry's work of 1948, but this is based solely on shell similarities, and some have suggested that the Kanab ambersnail should be re-classified as a separate species.[5]
The Kanab ambersnail was proposed for emergency listing in 1991, and the United States Fish and Wildlife Service (USFWS) has listed the Kanab ambersnail as endangered since 1992. The Kanab ambersnail is evaluated as Critically Endangered on the IUCN Red List of Threatened Species. In Utah, their habitat was threatened by commercial development,[6] whereas the Grand Canyon population is threatened by discharges from the Glen Canyon Dam which can sweep snails and their habitat downstream. Their natural predators are passerines and deer mice.[7][8]
[edit] Habitat
The Kanab ambersnail is typically found on host plants, primarily the scarlet monkeyflower and watercress,[9] but also sedges and rushes. It feeds on plant tissue, fungi, algae, and bacteria, using its radula to scrape off food.[10]
In 1996, 16% of the Ambersnail's habitat at Vaseys Paradise was destroyed in a flood, and a more disastrous previous flood in 1994 had probably already threatened the snail's habitat.[11] The suitable area for habitat in Three Lakes is believed to extend to an area 1.3 km long, and 90 m wide, and genetic diversity seems to indicate that the area is more stable than Vaseys Paradise. However their redistribution is also affected by the presence of their host plants and rock ledges.[12]
Three Lakes, a privately-owned wet meadow near Kanab, is one of only two natural habitats for the Kanab Ambersnail. The snail's habitat is threatened by commercial development by the owner of Three Lakes.
[edit] Population
Only two wild populations of the snail are known to exist,[4] specifically, Three Lakes near Kanab, Utah and Vaseys Paradise.[11] The latter was not discovered until 1991 when a survey of mollusks in the area was conducted.[12] There was formerly a third population present in Kanab, Utah, but it is believed to have become extirpated through the destruction of its habitat.[13]
[edit] Life cycle and characteristics
Ambersnails are hermaphroditic, possessing both male and female characteristics, and are believed to be capable of self-fertilization. In the wild they live for between 12 and 15 months. Young snails enter dormancy between October and November, becoming active again in March and April. Mature snails reproduce in the summer months. Despite being air-breathing molluscs, they can survive for up to 32 hours in cold, highly-oxygenated water, which may have helped to disperse its population around the Colorado Valley area since a controlled release was conducted in 1998.[3]
[edit] Recovery efforts
Releases have been conducted at three sites along Colorado river, each releasing 150 snails. The first of these releases was conducted in September 1998, and all sites were sufficiently high enough to not be flooded by normal dam activity. A second release was conducted at the same three sites in July 1999 to boost population densities and improve genetic variability, but only one of the three sites, Upper Elves Chasm, has established a new population.
[edit] References
- ^ Roth, B (1996). Oxyloma kanabense. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 26 November 2006.
- ^ Kanab Ambersnail. Utah Division of Wildlife Resources. Retrieved on November 25, 2006.
- ^ a b c Jeff Sorensen. Kanab Ambersnail (Oxyloma haydeni kanabensis). gf.state.az.us. Retrieved on November 26, 2006.
- ^ a b Mollusks. Grand Canyon National Park. Retrieved on November 25, 2006.
- ^ United States Fish and Wildlife Service. Endangered and Threatened Wildlife and Plants; Emergency Rule to List the Kanab Ambersnail as Endangered. United States Fish and Wildlife Service. Retrieved on November 26, 2006.
- ^ Randall Fitzgerald, Mugged by the State: Outrageous Government Assaults on Ordinary People and their Property, Regnery Publishing, Inc. (2003) ISBN 0-89526-102-2
- ^ USFWS. 1995. Kanab Ambersnail (Oxyloma haydeni kanabensis) recovery plan. U.S. Fish and Wildlife Service, Denver, Colorado. 21 pp.[1]
- ^ Stevens, L.E., V.J. Meretsky, D.M. Kubly, J.C. Nagy, C. Nelson, J.R. Petterson, F.R. Protiva, and J.A. Sorensen. 1997b. The impacts of an experimental flood from Glen Canyon Dam on the endangered Kanab Ambersnail at Vaseys Paradise, Grand Canyon, Arizona: Final Report. Grand Canyon Monitoring and Research Center, Flagstaff.[2]
- ^ Stevens, Lawrence E. et al (2001). "Planned Flooding and Colorado River Riparian Trade-Offs Downstream from Glen Canyon Dam, Arizona". Ecological Applications: 705.
- ^ Bill Vercammen. Success at snail's pace: KAS recovery update. desertusa.com. Retrieved on November 27, 2006.
- ^ a b Miller, Mark P.; Stevens, Larry P.; Busch, Joseph D.; Sorensen, Jeff A.; Keim, Paul. Amplified fragment length polymorphism and mitochondrial sequence data detect genetic differentiation in endangered southwestern U.S.A. ambersnails (Oxyloma epp.)
- ^ a b Brown, Steve; Cherlow, Jay R (2004). Bureau Of Reclamation: An Assessment of the Environmental Impact Statement on the Operations of the Glen Canyon Dam. DIANE Publishing, 77-8. ISBN 0-7881-4057-4.
- ^ Clarke, A.H. 1991. Status survey of selected land and freshwater gastropods in Utah.
[edit] Further reading
- Kanab Ambersnail. Grand Canyon National Park. Retrieved on November 24, 2006.
- Oxyloma kanabense, on NatureServe Explorer.
