Species Profile: Alabama Cavefish (Speoplatyrhinus poulsoni)

Alabama Cavefish adult (Photo by Dante Fenolio)

Alabama Cavefish
Speoplatyrhinus poulsoni

Conservation status: IUCN Red List - Critically Endangered C2b; NatureServe - G1 (Alabama: S1). Listed as Endangered under the U.S. Endangered Species Act. Listed as Endangered in Alabama.

Description: Speoplatyrhinus poulsoni is an eyeless and depigmented amblyopsid cavefish that is pinkish-white in color with some structures, like fins, fin rays and the venter, that are quite translucent. Morphologically, it is the most cave-adapted fish in the family Amblyopsidae. Adults are typically 30-58 mm (1.2-2.3 inches) standard length (SL). Both adults and juveniles have an extremely elongate and flattened snout with a terminal mouth that is duck-like in appearance. Unlike other amblyopsid cavefishes, S. poulsoni lacks branched fin rays, and the fin membranes are incised giving a spiked appearance. Pelvic fins are lacking. Fin rays counts are as follows: 9 (9-10) dorsal, 8 (8-9) anal, 9 (9-11) pectoral, and 22 (21-22) caudal. The lateral-line system is hypertrophied and their is an elaborated system of superficial neuromasts arranged in distinct ridges on the head and along the body. Caudal sensory papillae are also found on the caudal fin. Scales are small, imbedded, and cycloid. The urogenital pore and anus are jugular in position. Recent molecular work indicates that S. poulsoni is most closely related to the Southern Cavefish (Typhlichthys subterraneus).

Lateral view of an Alabama Cavefish.

Distribution: Speoplatyrhinus poulsoni is known from just a single cave system, Key Cave, in Lauderdale Co., Alabama, within the Tennessee River watershed. Despite numerous surveys for cavefishes in other caves in close proximity to Key Cave along the Tennessee River and elsewhere, no additional populations of S. poulsoni have been found in northwestern Alabama.

Habitat: Key Cave is a maze-like cave system developed in the Mississippian-aged Tuscumbia Limestone. The aquatic habitat in Key Cave consists of a series of pools with little flow that occur in a zone of seasonal oscillation of the local water table. Several of these pools are quite deep reaching depths of up to 5 m depending on seasonal water levels. Significant bat roosts occur near at least two pools where guano occasionally slides or falls into the water.

Close-up dorsal view of head.

Natural History: Little is known regarding many aspects of the life history and ecology of S. poulsoni because of its rarity. Some authors have speculated that females may incubate eggs and protect young fry within the branchial chamber, based on the jugular position of the vent. This behavior has been observed in some populations of the related Northern Cavefish (Amblyopsis spelaea) but has yet to be demonstrated for any other amblyopsid, including S. poulsoni. Individuals as small as 12-15 mm SL have been observed in February and November, suggesting that S. poulsoni may breed in the summer months. In addition, the female holotype contained developing ova and was collected in late May, also supporting a summer spawning season. The diet of S. poulsoni has not been studied but likely includes copepods, isopods, amphipods, and perhaps small crayfish. An undescribed species of cave shrimp was recently found in Key Cave and likely is prey for S. poulsoni. Predators are unknown and its thought that S. poulsoni is one of the top consumers in the Key Cave ecosystem. Sympatry of cavefish species is rare; however, S. poulsoni cooccurs with T. subterraneus within Key Cave. Typhlichthys subterraneus is common in caves throughout central Kentucky, central Tennessee, northern Alabama, and extreme northwestern Georgia. The absence of S. poulsoni but presence of T. subterraneus from nearby cave systems suggest that competitive interactions might influence the distribution of S. poulsoni. However, this hypothesis has not been examined.

Dorsal view of an Alabama Cavefish.

Conservation: Speoplatyrhinus poulsoni is one of the rarest vertebrates in North America. The population in Key Cave is small and no more than 10 individuals have ever been observed during a single survey.The U.S. Fish and Wildlife Service listed S. poulsoni as threatened in 1977 based on its restricted distribution, low abundance and potential threats to this species, including disturbance of a maternity colony of endangered Gray Bats (Myotis grisescens) whose guano is an important source of nutrients and energy for the aquatic ecosystem in Key Cave and groundwater pollution from pesticides as well as a proposed industrial park for the city of Florence. The threat status was later reclassified as endangered in 1988, as a sewage sludge disposal operation was found to occur within the recharge area of Key Cave. In addition, herbicide and pesticide runoff from cotton fields was found to have direct access into Key Cave via surface seeps. Loss of aquatic habitat from lowering of local groundwater levels by increased pumping also has been cited as a concern. The U.S. Fish and Wildlife Service purchased several hundred acres of land within the recharge zone of the cave and established the Key Cave National Wildlife Refuge. The agricultural land within the refuge is still maintained but cotton was replaced with corn and soybeans. In addition, all chemical use was restricted. This agricultural land is slowly being converted to upland forest and native grasslands. The most recent surveys for S. poulsoni indicate that the population is stable and recruitment is still occurring.

Fun Fact: Speoplatyrhinus poulsoni is named in honor of Dr. Tom Poulson, a prominent cave biologist who has studied amblyopsid cavefishes and other cave life since the late 1950s.

Select References

Boschung HT, Mayden RL. 2004. Fishes of Alabama. Smithsonian Institution Press, Washington.

Cooper JC, Kuehne RA. 1974. Speoplatyrhinus poulsoni, a new genus and species of subterranean fish from Alabama. Copeia 1974: 486-493.

Kuhajda BR. 2004. The impact of the proposed Eddie Frost Commerce Park on Speoplatyrhinus poulsoni, the Alabama cavefish, a federally endangered species restricted to Key Cave, Lauderdale County, Alabama. Endangered Species Update 21: 57.

Kuhajda BR, Mayden RL. 2001. Status of the federally endangered Alabama cavefish, Speoplatyrhinus poulsoni (Amblyopsidae), in Key Cave and surrounding caves, Alabama. Environmental Biology of Fishes 62: 215-222.

Niemiller ML, Near TJ, Fitzpatrick BM. 2012. Delimiting species using multilocus data: diagnosing cryptic diversity in the southern cavefish Typhlichthys subterraneus (Teleostei: Amblyopsidae). Evolution 66: 846-866.

Niemiller ML, Poulson TL. 2010. Subterranean fishes of North America: Amblyopsidae. Pp. 169-280 in: Trajano E, Bichuette ME, and Kapoor BG (eds). The biology of subterranean fishes. Science Publishers, Enfield, New Hamphire.

Poulson TL. 2009. New studies of Speoplatyrhinus poulsoni (Pisces: Amblyopsidae). Proceedings of the 15th International Congress of Speleology 3: 1337-1342.

Proudlove GS. 2006. Subterranean fishes of the world. International Society for Subterranean Biology, Moulis, France.

Romero A. 1998. Threatened fishes of the world: Speoplatyrhinus poulsoni Cooper & Kuehne, 1974 (Amblyopsidae). Environmental Biology of Fishes 62: 293-294.

U.S. Fish and Wildlife Service. 1977. Final threatened and status and critical habitat for five species of southeastern fishes. Federal Register 42: 45526-45530.

U.S. Fish and Wildlife Service. 1982. Recovery plan for the Alabama cavefish, Speoplatyrhinus poulsoni Cooper and Kuehne 1974. Prepared by Cooper JE, North Carolina State Museum of Natural History. 72pp.

U.S. Fish and Wildlife Service. 1988. Endangered and threatened wildlife and plants: reclassification of the Alabama cavefish from threatened to endangered. Federal Register 53: 37968-37969.

U.S. Fish and Wildlife Service. 1990. Alabama cavefish, Speoplatyrhinus poulsoni Cooper and Kuehne 1974 (Second Revision) recovery plan. Prepared by Cooper JE, North Carolina State Museum of Natural History. Revised by Stewart JH, U.S. Fish and Wildlife Service, Atlanta, Georgia. 17pp.