Typhlichthys subterraneus is restricted in its geographic range to the North American continent. Some scientists believe their range was continuous in the past and may still be, but it is difficult to determine. Many scientists agree the range is now disjunct, with species inhabiting specific cave systems in Tennessee, Alabama, Missouri, Arkansas, Oklahoma, and Kentucky, but always south of the limit of glaciation. Dispersal is presumed to be through underground water channels.

Biogeographic Regions: nearctic (Native )

endemic to a single nation

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) This fish is widely distributed in two major, apparently disjunct karst regions west and east of the Mississippi River: Ozark Plateau of southern Missouri and northeastern Arkansas; and Cumberland and Interior Low plateaus of northern Alabama (to Coosa River system), northwestern Georgia, central Tennessee and Kentucky, and possibly extreme southern Indiana (generally regarded as an invalid record; Lewis 2002). Some apparently isolated populations actually may be in contact through subterranean channels (Etnier and Starnes 1993), whereas other populations, such as those in the eastern Mississippian Plateau of Kentucky may be truly disjunct (Cooper and Beiter 1972). Reported occurrences of this species in northeastern Oklahoma and Greene County in southwestern Missouri are based on Amblyopsis.

Typhlichthys subterraneus is a small fish reaching a maximum length of 9 centimeters. Individuals have large broad heads with rudimentary eyes hidden under the skin. Normally there is no pigment on the body, although tests have shown that coloration does appear if a specimen is removed from its habitat and exposed to light. Southern cavefish do not have pelvic fins. There are 7-10 dorsal rays, 7-10 anal rays, and 10-15 caudal rays. The body, head, and caudal fin is covered by sensory papillae.

Range length: 9.0 (high) cm.

Average length: 8.6 cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Length: 7 cm

• Freshwater

Southern cavefish inhabit subterranean waters and are troglobitic. They prefer caves that are near the watertable and have low energy flows. These caves have water temperatures of 10 to 15 degrees C. Southern cavefish have adapted to life in an extreme habitat that includes factors such as low food supply, seasonal water level changes, and an aphotic environment.

Habitat Regions: temperate

Habitat Type: Freshwater

Comments: This troglodytic species is known only from cool (10-14 C), clear, waters of cave streams, undergound lakes, wells, and outlets of springs, over mixed gravel, sand, and mud substrates (Burr and Warren 1986, Pflieger 1997, Boschung and Mayden 2004). Most occupied locations have a permanently effluent spring that discharges at the surface into a spring pool or that contributes to a cave stream or the filling of a sink hole (Noltie and Wicks 2001). Immersed substrates vary from exposed bedrock to clays; coarser substrates generally are found where the spring upwelling occurs, especially where the effluent flows are large and the spring throat expansive (Noltie and Wicks 2001).

However, the sites where southern cavefish are seen appear not to be representative of the deep, subterranean aquatic habitats (up to at least 240 meters below the land surface) in which most individuals occur. "Instead, they represent atypical habitats into which fish have been flushed/washed/carried or transported" (Noltie and Wicks 2001). Southern cavefish appear not to be long-term inhabitants of the spaces that are humanly accessible (Noltie and Wicks 2001).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Food is scarce. Typhlichthys subterraneus forages using its sensory papillae in midwater and on the substrate. When prey is within 10 mm of the mouth, capture movements are commenced. Southern cavefish have distance perception and spatial memory which aid in foraging behavior. Their diet consists mainly of copepods (60-90%, by volume).

Foods eaten include trichopteran larvae, tendepedid larvae, cladocerans, isopods, crayfish, and copepods.

Animal Foods: insects; aquatic crustaceans

Primary Diet: carnivore (Eats non-insect arthropods)

Comments: Diet includes larval insects, cladocerans, isopods, crayfish, copepods, amphipods, and isopods (Poulson 1963, Cooper and Beiter 1972, Boschung and Mayden 2004). Cannibalism possibly may be a factor in keeping populations small (Boschung and Mayden 2004).

These animals are the top predators in the environments in which they live.

There are no known predators of southern cavefish.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 - 300

Comments: This species is represented by a large number of occurrences (subpopulations). However, the precise number of distinct occurrences is unknown because the degree of connectivity among the various observed populations is uncertain.

East of the Mississippi River, Etnier and Starnes (1993) mapped 27 collection sites in Tennessee. Mettee et al. (1996) mapped about 50 collection sites in Alabama, and Boschung and Mayden mapped 39 widely distributed collection sites in Alabama. Burr and Warren (1986) mapped several collection sites in Kentucky, and for the period 1984-2005 the Kentucky Department of Fish and Wildlife Resources mapped at least 8 collection sites. Lewis (2005) documented cave occurrences in Tennessee in 19 caves in Fentress, Franklin, Gruncy, Marion, Overton, Putnam, VAn Buren, Warren, and White Cos.

West of the Mississippi River, Pflieger (1997) mapped 25 collection sites in Missouri. Robison and Buchanan (1988) mapped 3 (one pre-1960) collection sites in Arkansas. Noltie and Wicks (2001) noted the same number of sites in Missouri and Arkansas.

2500 - 1,000,000 individuals

Comments: Total adult population size is unknown but probably is at least several thousand and likely much larger than that. For example, although most observed populations are relatively small (see following), at least "hundreds" of southern cavefishes were found dead in a spring 21 kilometers from a toxin spill in Missouri; based on cavefish habitat and geological considerations, Noltie and Wicks (2001) believed that the actual number killed was much larger (most dead cavefishes would have remained hidden in the aquifer). Because cavefish habitat appears to be extensive (Noltie and Wicks 2001), and most southern cavefish habitat is inaccessible to humans, available information from observable populations probably greatly underestimates the species' true abundance.

Population censuses for six caves by Poulson (1963) yielded estimated that ranged from 7-150 fish per cave, with a mean population size of 41. "In a given cave, population sizes vary from a few individuals to a couple of hundred" (Boschung and Mayden 2004). Pflieger (1997) mentioned a Missouri population in an underground lake that conservatively included at least 90 individuals. Robison and Buchanan (1988) reported observations of about 20 individuals in each of two caves in Arkansas, though these values do not necessarily represent the full population size. In Kentucky, this species is "sporadic and generally uncommon" (Burr and Warren 1986).

Southern cavefish use touch and their thigmotaxic sense to maintain their position in the water column. Their use their sense of touch extensively to detect prey. Other sensory modalities are possible, but are unknown currently.

Eggs are held in the gills of females until they hatch. Otherwise, little is known of development in southern cavefish.

The expected life span is four years in the wild.

Typical lifespan

Status: wild: 4.00 (high) years.

Average lifespan

Status: captivity: 4 years.

There is little known of mating behavior in southern cavefish.

Breeding is presumed to occur in the spring season when, unfortunately, the caves are inaccessible due to high water levels.The rise in the water table drives a temperature and alkalinity decrease and also results in an increase in food availability. In response to such stimuli, a hormone is released and the gonads complete their maturation. Females are low in fecundity, producing an average of 49 eggs per female that range from 2.0-2.3 millimeters in size. It is estimated that 50% of adult females breed each year. Because of this, population sizes are small, and as a result, mates are difficult to find. Therefore, a great amount of energy is put into the rearing of young.

Breeding interval: Breeding occurs each year.

Breeding season: Breeding is thought to occur in spring.

Average number of offspring: 49.

Range age at sexual or reproductive maturity (female): 2.0 (high) years.

Range age at sexual or reproductive maturity (male): 2.0 (high) years.

Key Reproductive Features: iteroparous ; seasonal breeding ; sexual

Eggs are incubated in the gill chambers of the parent female for an unspecified amount of time. Fry have been recorded in June and July.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)

Breeding behavior may be similar to that of the northern cavefish (Pflieger 1975). As few as 50% of the adult female population may breed in any one year. Species may be a branchial (i.e., gill chamber) brooder, which is also indicated by the position of the jugular vent and the size and shape of the gill chamber (Poulson 1963). Breeding may take place in the spring, after which the eggs and then young are probably held in the gill chamber for 4 to 5 months to June or July (Poulson 1963, Pflieger 1975, Robison and Buchanan 1992). Females become sexually mature in 2 years; individuals live up to at least 4 years in the wild (Poulson 1963), more than a decade in captivity (Noltie and Wicks 2001). Low reproductive capacity.

• Needs updating

Because the habitat of southern cavefish is so unique and because population numbers are normally low, they are regarded as a vulnerable species. Any amount of habitat that is destroyed or altered would have a significant impact. However, many of the cave systems inhabited by Typhlichthys subterraneus are protected by govenmental regulation (e.g., Mammoth Cave in Kentucky).

US Federal List: no special status

IUCN Red List of Threatened Species: vulnerable

United States

Rounded National Status Rank: N4 - Apparently Secure

Rounded Global Status Rank: G4 - Apparently Secure

Reasons: Discontinuous range in subterranean waters of Missouri and Arkansas west of the Mississippi River, and Kentucky, Tennessee, Alabama, and Georgia east of the Mississippi; many occurrences, large area of potentially occupied habitat; possibly declining, but trends are poorly known because most of habitat is inaccessible; vulnerable to groundwater pollution and sedimentation.

Intrinsic Vulnerability: Highly to moderately vulnerable.

Comments: Rate of increase and reproductive capacity are low.

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Current trend is presumed to be relatively stable or slowly declining as a result of ongoing habitat degradation, but the actual degree of decline, if any, is unknown. Warren et al. (2000) categorized this species a "vulnerable" (may become endangered or threatened by relatively minor disturbances to habitat or deserves careful monitoring of distribution and abundance).

Global Long Term Trend: Increase of 10-25% to decline of 50%

Comments: Historical and recent (through May 2005) records in Kentucky indicate an apparently reduced extent of occurrence, area of occupancy, and number of subpopulations (Kentucky Department of Fish and Wildlife Resources). The species also appears to have disappeared from many caves in Alabama (Boschung and Mayden 2004). However, these reports are based on observable (accessible) populations, and trends in the large extent of inaccessible habitat are unknown. Noltie and Wicks (2001) cautioned that periodic censuses at accessible sites may not accurately reflect trends in the population as a whole, most of which is inaccessible.

Degree of Threat: C : Not very threatened throughout its range, communities often provide natural resources that when exploited alter the composition and structure over the short-term, or communities are self-protecting because they are unsuitable for other uses

Comments: The habitat of the southern cavefish is fragile and vulnerable to water quality degradation resulting from human activities. Boschung and Mayden (2004) reported that professional spelunkers told them that this species is disappearing from many caves in Alabama as a result of groundwater depletion and pollution. The population in Sloans Valley Cave, Kentucky, which may be a distinct taxon (Cooper and Beiter 1972), was at least formerly at risk from heavy metal runoff from a landfill site (Tercafs 1992), but Hopper and Hansen (1996) described an optimistic outcome for this site (fide Proudlove 2001). A population was extirpated from Hidden River Cave in Kentucky after gross pollution lasting several decades (Lewis 1996).

However, this species "is thought to be in no immediate danger so long as ground water quality is not threatened by percolation of agricultural chemicals or other contaminants" (Etnier and Starnes 1993). Contaminants that potentially could negatively affect southern cavefish habitat and populations include toxins from sewage plant effluent, septic field waste, campground outhouses, feedlots, grazing pastures, or any other source of human or animal waste; pesticides or herbicides used for crops, livestock, trails, roads, or other applications; fertilizers used for crops or lawns; toxins from mineral exploration and development, such from zinc and lead mines in the Ozarks; and hazardous material introductions via accidental spills or deliberate dumping, including road salting (see Lewis 2002). Pflieger (1997) described an incident in Missouri where a pipeline break 21 kilometers from a cavefish site in a spring resulted in leakage of fertilizer into the spring's aquifer and mass mortality of cavefishes and other species.

Habitat alteration due to sedimentation is a pervasive threat potentially caused by logging, road or other construction, trail building, farming, or any other kind of development that disturbs ground cover (Lewis 2002). Sedimentation potentially changes cave habitat, blocks recharge sites, or alters flow volume and velocity. Pesticides and other harmful compounds like PCBs may adhere to clay and silt particles and be transported into caves via sedimentation (Lewis 2002).

Dewatering of karst systems by well drawdown and mine pumping may also be a threat to the cavefish and other groundwater species (Lewis 2002).

Construction of roads or trails near cave entrances encourages human entry into cavefish habitat. Human intrusion results in increased risk of vandalism or littering, trampling of fauna, introduction of non-native microbial flora, or introduction of hazardous materials such as spent carbide batteries (see Lewis 2002).

Biological Research Needs: Methods are needed to determine cavefish presence and abundance in areas that are currently inaccessible.

Global Protection: Several (4-12) occurrences appropriately protected and managed

Comments: At least several occurrences are adequately protected. Many occurrences in Missouri are in areas protected by public ownership (Pflieger 1997). In Missouri, most major southern cavefish sites are gated or otherwise inaccessible (Jo Schaper). In Missouri, some of the caves on national forest land are protected from human visitation or habitat alteration simply by their physical condition and/or location (Lewis 2002). Management of areas near cavefish-occupied caves in the Mark Twain National Forest in Missouri (Lewis 2002) provides good protection for cavefish.

Needs: Protection of groundwater quality is a basic need.

There are no adverse effects of southern cavefish for humans.

Southern cavefish are important members of their ecosystems and important research subjects for understanding evolution in extreme environments.

Positive Impacts: research and education

Comments: Monotypic genus; synonyms include T. OSBORNI and T. WYANDOTTE (Lee et al. 1980). Genetic studies by D. Noltie and D. Bergstrom were underway in Missouri in the early 1990s (Figg 1991, 1993).