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Cambarus zophonastes

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA ARTHROPODA MALACOSTRACA DECAPODA CAMBARIDAE

Scientific Name: Cambarus zophonastes
Species Authority: Hobbs & Bedinger, 1964
Common Name(s):
English Hell Creek Cave Crayfish, Hell Creek Crayfish

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B2ab(iii) ver 3.1
Year Published: 2010
Date Assessed: 2010-06-01
Assessor(s): Cordeiro, J. & Thoma, R.F.
Reviewer(s): Collen, B. & Richman, N.
Contributor(s): Livingston, F., Livingston, F., Soulsby, A.-M., Batchelor, A., Dyer, E., Whitton, F., Milligan, H.T., Smith, J., Lutz, M.L., De Silva, R., McGuinness, S., Kasthala, G., Jopling, B., Sullivan, K. & Cryer, G.
Justification:
Cambarus zophonates has been assessed as Critically Endangered under criterion B2ab(iii). This species has an area of occupancy of less than 0.5 km2 and occurs at just two localities which are severely fragmented. In 2006, 23 individuals were recorded, 14 at Hell's Creek and nine at Nesbitt Cave. Extensive searches have been conducted to locate other populations of this species in the area, but so far none have been recorded. This species is threatened by a variety of factors, namely groundwater pollution, vandalism, trespassing, collectors and a reduction in nutrient availability. The US Fish and Wildlife Service (USFWS) has put in place an Action Plan for Hell's Creek Cave including the installation of cave gates, fences and a monitoring programme. However, even with these preventative measures in place, human disturbance continues to occur and degrade this species habitat. No action plan has been initiated for Nesbitt's Cave. Ground water pollution continues to occur, with no measures in place to prevent refuse dumping, the repairing of septic tanks or sewage contamination. Due to the delicate environment that this species inhabits, its access to sufficient nutrients is limited, and reliant on Grey Bat guano and leaf litter from flood waters. However, Grey Bats have not been recorded in Hell's Creek Cave for some time, thus limiting nutrient intake of this species. So far, it is unknown what impact this reduction in nutrients is having on this species. Even with an Action Plan in place, this species continues to be susceptible to habitat degradation and human disturbance.
History:
1996 Critically Endangered
1994 Endangered (Groombridge 1994)
1990 Endangered (IUCN 1990)
1988 Endangered (IUCN Conservation Monitoring Centre 1988)
1986 Endangered (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description: This species is found in Hell Creek Cave and has recently expanded to Nesbitt Spring Cave, Stone County, Arkansas, USA (Graening et al. 2006). Surveys have been initiated at 170 other caves; no additional populations have been located. This species has an inferred area of occupancy (AOO) of less than 0.5 km2.
Countries:
Native:
United States (Arkansas)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species was previously known from one pool, at one cave.  Recent survey work has located an additional population, also in Stone County, Arkansas (Graening et al. 2006). An additional 29 cave streams in Stone County revealed no additional populations beyond this one and it was also not found in another 50 caves outside this area.

Up until recently, the total population of this species had been estimated at fewer than 50 individuals (US Fish and Wildlife Service 1988) from a single cave at the type locality. Historically published observed specimens from this locality include 5 specimens in 1961, two in 1972, 15 in 1983, 13 in 1990, 6 in 2000 (two in the first pool and four more in non-submerged passages), 8 in 2001 (most upstream to 300 m in unmapped passages), and 6 in 2003 (Graening et al. 2006).  In 1992, several stygobitic crayfish were reported from the second locality and later censuses confirmed the identity of two specimens in 2002 and 14 in 2005 (Graening et al. 2006).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: This species is found in subterranean streams, between one and two meters wide and one to eight meters deep (Hobbs and Bedinger 1964). The water temperature was 14.5oC. This species is found both on the rock sides and mud bottom of the streams (Hobbs and Bedinger 1964). This species dislikes turbid water and will crawl up the sides of the stream to clearer water or move to deeper areas (Hobbs and Bedinger 1964). It is reliant on nutrients from Grey Bat guano, which use the caves to roost, and from leaf litter which enters the caves by floodwaters (Natural Heritage 2009). The caves are situated in an area of sinking streams which supply groundwater (Graening et al. 2006). The groundwater recharge area is 9 km2 (Natural Heritage 2009).
Systems: Freshwater

Threats [top]

Major Threat(s): This species is threatened by groundwater contamination, vandalism, collectors, trespassing, and the removal of the Grey Bat population. The two caves where this species is located are in an area characterized by sinking streams. These streams are vital for the transition of nutrients to the caves. However, these also cause pollutants to be easily introduced to the groundwater system through the recharge zone (Natural Heritage 2009). The caves are downstream from Mountain View City and a major highway resulting in the introduction of sewage, siltation from construction, and chemicals from spills into the recharge system (Natural Heritage 2009). Illegal refuse dumping, salvage yards and malfunctioning septic tanks are also polluting the groundwater system (Graening et al. 2006). An electrical transmission line also crosses the recharge area, and herbicides have been used to clear the right-of-way (Natural Heritage 2009). Vandalism, trespassing and collectors are also major threats to C. zophonastes. Due to its sensitivity to water disturbance and turbidity, and due to its low population numbers, it is susceptible to the removal of individuals and human disturbance (Graening et al. 2006). Once, 16,000 grey bats roosted in the caves, but for several years they have not been recorded. The loss of nutrients from the guano may have limited the population size of C. zophonastes and is now reliant on leaf litter nutrients which are brought in from floodwaters.

The federal recovery plan (US Fish and Wildlife Service 1988) cited limiting factors such as destruction of habitat, scientific collection, disturbance by amateur cavers, and lack of reproduction. Updated threat information can be found in Graening et al. (2006). Although over-collection may have been a significant mortality factor in the past, scientific collection has ceased and no amateur collection is known.  Recreational caving impacts and habitat destruction continue to be potential factors threatening the viability of this species. 

Conservation Actions [top]

Conservation Actions:

This species has been given a Global Heritage Status Rank of G1 by NatureServe (Taylor et al. 2007, NatureServe 2009) and 'endangered' by the American Fisheries Society (Taylor et al. 2007).
The US Fish and Wildlife Service compiled a species recovery plan for this species in 1988, citing limiting factors and stating that there should be regular surveys of the population and analyses of habitat quality (Graening et al. 2006). As a result of this action plan, cave gates and fencing have been installed at HellsCreekCave, although trespassing and vandalism continue to occur (Graening et al. 2006). The land adjacent to HellsCreekCave is protected as part of the Hells Creek Natural Area (Graening et al. 2006). Protection of the cave and its recharge zone is being implemented largely through the Arkansas Natural Heritage Commission and The Nature Conservancy. The groundwater recharge area was defined as a 906 ha zone.  Lands adjacent to the cave are protected within a Natural Area and attempts to expand that area are underway.  A site conservation and management plan has been prepared and installation of cave gates, fencing, and monitoring has secured the entrances to the cave although trespass and vandalism continue to occur (Graening et al. 2006, USFWS 1988).

There are no conservation measures present at NesbittCave, and the groundwater recharge zone has not been defined.  No conservation activities have occurred at this cave or within the watershed but the landowner remains dedicated to the protection of the groundwater resource (Graening et al. 2006, USFWS 1988). No measures have been put in place to reduce groundwater pollution, however.

Citation: Cordeiro, J. & Thoma, R.F. 2010. Cambarus zophonastes. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 20 September 2014.
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