Kentucky Cave Shrimp

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Kentucky Cave Shrimp

Palaemonias ganteri

ListedOctober 12, 1983
FamilyAtyidae (Freshwater shrimp)
DescriptionNearly transparent decapod crustacean with only rudimentary eyestalks.
HabitatCave streams and pools.
FoodProtozoans, insects, fungi, algae.
Reproduction16-24 eggs.
ThreatsGroundwater contamination; predators.


Kentucky cave shrimp (Palaemonias ganteri ) is a small, nearly transparent decapod crustacean characterized by rudimentary eyestalks and bristlelike hairs on its unequally sized pincers. It is superficially similar to a common ocean shrimp, but the presence of reduced eyes and a lack of pigmentation indicate that this crustacean has survived underground for perhaps thousands of years.


The cave shrimp is a nonselective grazer, feeding on sediments and detritus. Tiny protozoans and insects, fungi, and algae appear to make up the bulk of the diet. This species breeds year-round. Females produce 16-24 eggs.


Kentucky cave shrimp inhabits the lowest passages of the Flint-Mammoth Cave System, the most extensive cave system ever discovered. In the absence of light, food sources must enter the cave in groundwater. The cave drainage comprises a complex network of still pools and flowing streams. The free-swimming Kentucky cave shrimp are concentrated in deeper pools where currents are minimal.


Kentucky cave shrimp is endemic to the Flint-Mammoth Cave System, extending beneath Edmonson, Barren, and Hart counties, Kentucky. This broad system of passages and pools includes the Mystic, Echo, Styx, and Colossal rivers, Lake Lethe, and the Golden Triangle. In 1983 two crustaceans resembling the Kentucky cave shrimp were sighted in Blue Spring (Hart County), Kentucky. If confirmed, this sighting would extend the known range of the species outside of the caves proper. Surveys in the early 1980s examined 95 sites in 37 caves and produced a population estimate for the Kentucky cave shrimp of only 500 individuals.


The Flint-Mammoth Cave region has been extensively developed for tourism, and, although this shrimp has weathered many individual events, the cumulative effects of development on the quality of the groundwater may now be materializing. Surveys have shown a significant decline in the Mammoth Cave fauna since the mid-1980s due to pervasive groundwater pollution. The shrimp's small population makes it particularly vulnerable to extinction.

Because groundwater contamination recognizes no convenient boundaries, protecting the aquatic habitat of the caves is considered a regional problem. Several communities adjacent to the Mammoth Cave National Park are known to have inadequate sewage treatment facilities or lack facilities altogether. Untreated sewage could enter the cave system at numerous points and contribute to oxygen deficiencies or nutrient toxicity. Because the cave system is interconnected, the primary drainage runs directly through the caves, and harmful substances entering from the surface are immediately transported throughout the system. Additionally, contaminants from traffic accidents or roadside businesses have been introduced into the drainage. In 1980 a truck carrying toxic cyanide salts overturned on Interstate Highway 64 south of the park, and the resulting contamination killed thousands of aquatic cave organisms.

The McCoy Blue Spring, Suds Spring, and part of Groundwater Basins are located in oil fields where oil and gas are drilled. Brine from these wells is commonly washed into a sinkhole or into the Green River. It is also common for drillers to pull out casing, leading to the intrusion of oil, gas, and brine from the deeper strata that underlie the relatively shallow cave. In addition, agricultural development in the national park region has the potential of affecting cave fauna by contributing to the erosion of surface land that drains into the cave system. The introduction of rainbow trout into the watersheds of the Mammoth Cave National Park region may also contribute to the decline of the cave shrimp. Although the trout population seems to be relatively small, it may have successfully adapted to the cold subterranean waters, utilizing cave fauna as a food source. The trout has been observed eating the cave shrimp.

Conservation and Recovery

The U. S. Fish and Wildlife Service (FWS) and the Park Service hope to work closely with county and municipal governments to improve regional standards of sewage treatment and disposal. Additionally, a plan has been proposed to reroute vehicles carrying toxic chemicals, solvents, and fuels to provide a measure of security for the watershed of the Mammoth Cave National Park. It may be necessary to control the rainbow trout population as well. A section of habitat considered critical for the survival of this species has been designated to include 1 mi (1.6 km) of the Roaring River passage of Mammoth Cave. The FWS has stated that it may expand the size of critical habitat in the future, if groundwater contamination worsens.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
Telephone: (404) 679-4000

U. S. Fish and Wildlife Service
Asheville Ecological Services Field Office
160 Zillicoa St.
Asheville, North Carolina 28801-1082
Telephone: (828) 258-3939
Fax: (828) 258-5330


Environmental Protection Agency. 1981. "Final Environmental Impact Statement, Mammoth Cave Area, Kentucky: Wastewater Facilities." Report No. EPA 904/9-81-076. Environmental Protection Agency, Atlanta.

Holsinger, J. R. and A. T. Leitheuser. 1983. "Eco-logical Analysis of the Kentucky Cave Shrimp, Palaemonias ganteri Hay, Mammoth Cave National Park (Phase III)." Report. National Park Service, Atlanta.

Leitheuser, A. T., and J. R. Holsinger. 1983. "Eco-logical Analysis of the Kentucky Cave Shrimp at Mammoth Cave National Park." Central Kentucky Cave Survey Bulletin 1: 72-80.

U. S. Fish and Wildlife Service. 1983. "Determination of Endangered Status and Designation of Critical Habitat for the Kentucky Cave Shrimp." Federal Register 48: 46337-46342.

U. S. Fish and Wildlife Service. 1988. "Recovery Plan for the Kentucky Cave Shrimp." U. S. Fish and Wildlife Service, Atlanta.

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Kentucky Cave Shrimp

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