Alabama Cavefish

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Alabama Cavefish

Speoplatyrhinus poulsoni

Status	Endangered
Listed	September 9, 1977: Threatened
Reclassified	September 28, 1988: Endangered
Family	Amblyopsidae (Cavefish)
Description	Small, eyeless, albino cavefish.
Habitat	Underground pools and streams in caves.
Food	Aquatic invertebrates and cavefish.
Reproduction	Probably incubates eggs under the gills.
Threats	Low numbers; degradation of groundwater quality.
Range	Alabama

Description

The Alabama cavefish, Speoplatyrhinus poulsoni, is about 3 in (8 cm) long and has no discernible pigmentation, appearing pinkish-white. It is eyeless and has transparent fins and skin. It has a large head, which makes up more than one-third of its length.

The Alabama cavefish is the rarest American cavefish and one of the rarest freshwater fishes in North America.

Behavior

Although little is known about the Alabama cave-fish, it probably incubates eggs within a chamber underneath the gills. There's some evidence to suggest that it matures late and reproduces until the end of its life. It feeds on small aquatic invertebrates and smaller cavefish and has a life span of five to 10 years.

Habitat

The cavefish's only known habitat is Key Cave in Alabama. The cave has cool, year-round temperatures and receives no direct light. It is located within the Warsaw limestone formation, which is a large, stable aquifer and an excellent conveyer of groundwater. The Warsaw limestone rests on underlying rock strata that are honeycombed with channels to allow passage of groundwater.

Flooding is generally responsible for washing organic matter into the pools and streams within the caves, providing food for cave fauna, which in turn provides food for higher lifeforms. In Key Cave, the guano of the gray bat is probably the major source of the organic matter at the bottom of the food chain.

The aquatic community in this cave includes fairly large populations of two cave-adapted cray-fish, as well as numerous isopods and amphipods.

Distribution

The Alabama cavefish has been found only in Key Cave in Lauderdale County, Alabama. Only nine specimens have ever been collected. Because the underground water system in the area is so widespread, it was hoped that the cavefish had been dispersed to other sites. However, studies of 120 other caves in the area, conducted since 1977, have failed to locate any other cavefish populations. The number of individuals in the Key Cave population is estimated to be less than 100. In 1988 the Alabama cavefish was reclassified from Threatened to Endangered.

Threats

The quality of the groundwater directly affects the fragile ecology of the cave. When water is degraded by fertilizers, pesticides, or sewage run-off, the food supply for the cavefish diminishes, which in turn reduces its longevity and reproductive capabilities. The U. S. Fish and Wildlife Service (FWS) is working with the Environmental Protection Agency to control sources of groundwater pollution in the area and to advise about the impact of any construction on the runoff patterns. The population level of the gray bat within the cave also affects the Alabama cavefish. In recent years, bat numbers have declined, reducing guano, and lessening habitat viability. Food availability is the primary limiting factor on population, which is directly related to the viability of the bat inhabitants of the cave. In Key Cave the bat population diminished by half over a 10-year period.

Conservation and Recovery

FWS personnel are currently exploring management techniques for stabilizing the population of the Endangered gray bat (Myotis grisescens ; see separate entry). As the Gray Bat Recovery Plan is implemented, it will also benefit the cavefish. Further research is needed to plan the recovery of the Alabama cavefish. The little that is currently known, however, is not encouraging. Captive breeding of cave-dwelling species has invariably failed in the past, and it is not considered a viable recovery strategy for the Alabama cavefish. Transplanting the fish to other sites is not considered feasible, and biologists' options are limited.

The Recovery Plan calls for determining the recharge requirements of Key Cave; monitoring the Key Cave aquifer and water quality; determining the impact of the loss of bats in Shelta Cave; prohibiting human disturbance of the caves; and controling agricultural practices in the recharge area.