|Scientific Name:||Typhlichthys subterraneus|
|Species Authority:||Girard, 1859|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Reviewer(s):||Smith, K. & Darwall, W.R.T.|
|Facilitator/Compiler(s):||Hammerson, G.A. & Ormes, M.|
This species has a fairly large extent of occurrence and number of locations, an unknown but probably large area of occupancy and population size, and an unknown trend over the past 10 years or three generations. It is listed as Near Threatened because the species is vulnerable to declines from degradation of ground water quality, but probably it is not currently declining fast enough to qualify for any of the threatened categories under Criterion A (reduction in population size). Pending further data on the rate of decline, it is possible that a small increase in the rate of decline could put it in the Vulnerable category.
|Range Description:||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.|
Native:United States (Alabama, Arkansas, Georgia, Kentucky, Missouri, Tennessee)
|Range Map:||Click here to open the map viewer and explore range.|
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 eight 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 three (one pre-1960) collection sites in Arkansas. Noltie and Wicks (2001) noted the same number of sites in Missouri and Arkansas.
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 estimates 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).
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.
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 as "vulnerable" (may become endangered or threatened by relatively minor disturbances to habitat or deserves careful monitoring of distribution and abundance).
|Habitat and Ecology:||
This troglodytic species is known only from cool (10-14°C), clear, waters of cave streams, underground 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).
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 (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).
Methods are needed to determine cavefish presence and abundance in areas that are currently inaccessible. Better information is needed on area of occupancy and population size in subterranean waters. Protection of groundwater quality is a basic need.
|Citation:||NatureServe 2014. Typhlichthys subterraneus. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 31 August 2015.|
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