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Hell Creek Crayfish
Cambarus zophonastes
Family: Cambaridae
Description: The Hell Creek crayfish
is an albinistic cave crayfish, lacking pigment in the body and eyes. Like some other obligate cave dwellers, this species eyes are reduced. The rostrum is characterized by strongly convergent margins bearing spines. The areola is narrow, and the cervical spine is small (if present at all).
| Status: |
Federally Listed Endangered (April 7, 1987) Global Rank: G1 State Rank: S1 |
Distribution: The only known population of Hell Creek crayfish is in Hell Creek Cave, Stone County, Arkansas. Intensive surveys at over 170 cave sites in north-central Arkansas failed to locate additional populations of this species.
Habitat: This species occurs in a cave pool located within a solution channel, most of which is wet year-round. An active stream flows through 1400 feet of cave passage, bringing surface material into the cave. The stream emerges 150 feet below the cave entrance as three springs. The springs are the principal sources of water for Hell Creek, a perennial stream that drains into the White River.
As with many cave systems in northern Arkansas, Hell Creek Cave is low in available nutrients and its inhabitants rely upon the import of organic matter. Nutrient input often takes the form of guano from bats or leaf litter. At one time, Hell Creek Cave was a summer roost for the federally listed endangered gray bat. Evidence suggests a maternity colony of some 16,000 gray bats once used the cave. However, it has been several years since gray bats have been observed in Hell Creek Cave. Loss of this nutrient source may have limited or reduced the population size of this species. Nutrient input into the cave now is primarily the result of floodwaters. In only a few hours after rains in the recharge area, the cave stream rises and becomes turbid, brining organic matter into the cave.
Diet: Unknown
Reproduction: Although details for this species are not well known, the Hell Creek crayfish likely has a low reproductive rate. This low reproductivity is partially due to the limited nutrients available in caves. Only 15 individuals of this crayfish have ever been observed at one time.
Conservation Status: Groundwater contamination represents a major threat to the Hell Creek crayfish. The only known population is in a region of Arkansas characterized by sinking streams. A sinking stream is a surface watercourse that loses significant quantities of water into the subsurface in very localized areas. Sinking streams are of extreme importance in supplying water and nutrients to caves. This rapid flow of water into caves also can allow the easy introduction of pollutants. Sewage, siltation from construction, and chemical spills along Arkansas Highway 9, and in the City of Mountain View, could enter the cave since the recharge area of Hell Creek Cave lies about one mile north of Highway 9 and Mountain View. An electrical transmission line also crosses the recharge area of the cave. The use of herbicides to clear the right-of-way for this line could contaminate the cave.
Due to this species very low population size, collection of specimens represents a second threat. The removal of crayfish, especially reproductively active females, could have a long-term impact on the population. Small population size, coupled with low reproductivity, limit this species ability to recover from any adverse event.
The Arkansas Natural Heritage Commission currently owns the Hell Creek Cave site and 213 surrounding acres. However, the recharge zone of the cave, which encompasses 3.5 square miles (9 square kilometers), is largely privately owned. Long-term conservation of this species will require protection of the headwaters section of this cave system from hazardous modifications or contamination.
