Typhlichthys subterraneus

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Osteichthyes
Classis: Actinopterygii
Subclassis: Neopterygii
Infraclassis: Teleostei
Superordo: Paracanthopterygii
Ordo: Percopsiformes
Familia: Amblyopsidae
Genus: Typhlichthys
Species: Typhlichthys subterraneus

Typhlichthys subterraneus is a species of fish in the Amblyopsidae family. It is endemic to karst regions of the eastern United States.

Taxonomy

Typhlicthys subterraneus is a member of the family Amblyopsidae, and is one of four troglobitic species. The Southern cavefish was described by Charles Frédéric Girard in 1859 from a well near Bowling Green, Warren County, Kentucky.[1] Later, Eigenmann in 1905 described both T. osborni and T. wyandotte based on differences in head width and eye diameter.[2] Typhlichthys osborni was described from Horse Cave, Kentucky, whereas T. wyandotte was described from a well near Corydon, Indiana, that was later destroyed. Recently, a well-like entrance into a cave on the property of a car dealership in Corydon was discovered and is believed to represent the type locality.[3] Regardless, this species is generally considered invalid and was not listed as a locality by Woods and Inger (1957).[4] Recent surveys in the vicinity of Corydon have failed to document T. subterraneus, finding only Amblyopsis spelaea. Typhlichthys eigenmanni (nomen nudum) was described as a fourth species in the genus from Camden County, Missouri. Recently, Parenti proposed that T. eigenmanni Charlton, 1933 is a subjective synonym of T. subterraneus.[5] Woods and Inger (1957) synonymized all species under T. subterraneus on the basis of lack of any clear geographic pattern in morphological variation.[4] A population from Sloans Valley Cave, Pulaski County, Kentucky, differs in several ways from populations to the southwest in Tennessee along the Cumberland Plateau and might represent an undescribed species.[6]

Distribution

This species is more commonly known as the Southern cavefish. This name is due to the southern states in which it is found, including Indiana, Alabama, Kentucky, Georgia, Missouri, Tennessee, Arkansas, and Oklahoma. The subterranean waters where the cavefish is found is divided by the Mississippi River. The regions that it occupies include the Ozark plateau of central and southeastern Missouri and northeastern Arkansas, the Cumberland and Interior low plateaus of northwest Alabama, northwest Georgia, central Tennessee and Kentucky, and southern Indiana. It has been observed that the species lives in solitary habitats and is mostly isolated.[7]

Ecology and conservation

Tyhplicthys subterraneus is mostly lentic, but can also be found in pools of streams near water tables. The cavefish feeds mostly on aquatic arthropods, such as amphipods and isopods. However, their metabolic rates are depressed in order to survive food shortages.[8] The reproductive capabilities of this species is considerably low, with fewer than 50 eggs per female. This provides restrictions on its capabilities for recovering from an even minor population decline. When young are produced, they brood in the female's gill chamber. Sexual maturity requires approximately two years, and the life span is approximately four years.[9]

Typhlichthys subterraneus is listed as a vulnerable species on the IUCN Red List.[10] Due to environmental threats, there has been a recent decline in geographical span and population density. This is perhaps due to pollution, lowering of the water table, flooding of reservoirs, or cave vandalism.[11] Throughout the range of occupation, the cavefish has been placed under various conservation categories. To reduce these detrimental effects, there are several things that can improve the Southern cavefish's status.[12]

Abstract

Typhlicthys subterraneus is a member of the family Amblyopsidae, and is one of four troglobitic species. Throughout this article, there will be a descriptive monitoring plan for this fish species. This species is more commonly known as the Southern cavefish. This name is due to the southern states in which it is found, including Indiana, Alabama, Kentucky, Georgia, Missouri, Tennessee, Arkansas, and Oklahoma. The subterranean waters where the cavefish is found is divided by the Mississippi River. The regions that it occupies include the Ozark plateau of central and southeastern Missouri and northeastern Arkansas, the Cumberland and Interior low plateaus of northwest Alabama, northwest Georgia, central Tennessee and Kentucky, and southern Indiana. It has been observed that the species lives in solitary habitats and is mostly isolated. Tyhplicthys subterraneus is mostly lentic, but can also be found in pools of streams near water tables. The cavefish feeds mostly on aquatic arthropods, such as amphipods and isopods. However, their metabolic rates are depressed in order to survive food shortages. The reproductive capabilities of this species is considerably low, with less than 50 ova per female. This provides restrictions on its capabilities for recovering from an even minor population decline. When young are produced, they brood in the female’s gill chamber. Sexual maturity requires approximately two years, and the life span is approximately four years. Due to environmental threats, there has been a recent decline in geographical span and population density. This is perhaps due to pollution, lowering of the water table, flooding of reservoirs, or cave vandalism. Throughout the range of occupation, the cavefish has been placed under various conservation categories. To reduce these detrimental effects, there are several things that can improve the Southern cavefish’s status.

Geographic Distribution of Species

Typhlichthys subterraneus can be found in several southern states which include Indiana, Missouri, Arkansas, Tennessee, Alabama, Georgia, and Kentucky. This species is widely dispersed among these states in two disjunct regions both east and west of the Mississippi River. Within this region are several areas in which it can be found. It is currently located in the Ozark Plateau of southern Missouri and northeastern Arkansas. The Southern cavefish can also be found in the Cumberland and Interior Low plateaus of northern Alabama, northwestern Georgia, central Tennessee and Kentucky. There have also been references of sightings in extreme southern Indiana as well. It has been observed that some distinct populations may be in contact through subterranean channels. However, species found in the eastern Mississippian Plateau of Kentucky may be truly disjunct. In Alabama, it is found in limestone cave environments in the Tennessee River drainage and in subterranean waters of the Coosa River system. Historically, there have been repeated sightings in Mammoth Cave in Kentucky for at least the past 50 years, as well as Mitchell’s Cave and Horse Cave as well. It is believed by some scientists, however, that the population may have been continuous in the past, and actually may still be. As evident by its common name, this troglodytic species is mostly found in cool, water cave streams, freshwater caves, underground lakes or wells, outlets of springs, over mixed gravel, sand, or mud substrates, or river basins around the Southeast. However, the sites where the Southern cavefish are found may not be truly representative of the true aquatic habitats that it occupies. The subterranean environment in which it most likely occupies is at least 240 meters below the land surface, which is not humanly accessible. The sitings of the cavefish are fish that have been carried or washed into these atypical habitats, and presumably are not long-term inhabitants of these locations.[13]

Ecology

This eyeless, pink-white fish can grow to be between 8-9 cm. The Southern cavefish’s diet can include larval insects, cladocerans (which can include water fleas), isopods, crayfish, copepods, amphipods, and isopods. The majority of the cavefish’s diet, however, is mainly copepods, which are small crustaceans that can be found in nearly every freshwater habitat. This particular crustacean occupies the Southern cavefish’s diet by a volume of 60-90%. Due to scarce food sources, the Southern cavefish forages using its sensory papillae in midwater and on the substrate. If its prey is approximately 10 mm from the fish’s mouth, it can capture its prey. Because of their lack of eyes, this species uses its extensive sense of touch to detect its prey. These fish prefer caves that are near to a watertable and have low energy flows. Normally, these caves have water temperatures between 10-15 °C. This species has adapted to life in these extreme cave habitats with possible factors including low food supply, seasonal water level changes, and an aphotic environment. There are currently no known predators for the Southern cavefish, and they are the top predators in the environments in which they occupy. Due to their extreme environments, this species has become well-adapted over time. To decrease their expended energy, this fish has developed decreased metabolic and growth rates, eye degeneration, and pigment loss. The caves that they occupy are energy-limited, which explains the need for extreme energy conservation and evolutionary adaptation. Their methods of navigation are attributed to a well-developed sensory papillae network and spatial memory as well. There are no adverse effects of the Southern cavefish for humans, although they are important members of their extreme ecosystems.[14] [13]

Life History

Although extensive research is being done on behaviors of Typhlichthys subterraneus, there is not much currently known concerning the mating behavior of this species. Breeding presumably occurs in the spring season, which is when most caves are inaccessible due to high water levels. This poses a problem in observing the breeding patterns of this species. Due to the increase in water levels, the conditions in the cave changes which drives mating behavior. These conditions include temperature and alkalinity decrease, as well as an increase in food availability. When exposed to these conditional stimuli, a specific hormone is released and the gonads reach their maturation. The expected life span is approximately four years in the wild, with females reaching sexual maturity after two years. It is estimated that 50% of adult females breed each year. However, females are low in reproductive capabilities, and they may produce an average of 49 eggs that can range from 2-2.3 mm in size. The eggs are incubated in the gill chambers of the female, although the brooding time is unknown. Scientists have estimated that it may take anywhere from four to six months for the eggs to mature. This results in low population sizes, which in turn makes finding mates difficult. Though there are no specific threats to the sites that this species inhabits, there are numerous potential threats that can affect the existence of the Southern cavefish. These can include pollution due to contaminated groundwater or runoff water flow. Human or animal waste could pose possible contaminations in these water sources. Also, pesticides or herbicides used for crops, as wells as deliberate dumping or accidental spills can cause pollution of these environments. These pollutions can be transported by way of sedimentation, which can alter the cave habitat, in turn changing the velocity and flow volume of the habitat.[15]

Current Management

The main reason for species endangerment for Typhlichthys subterraneus has been attributed to habitat degradation. Due to the uniqueness of the southern cavefish’s environment and low populations numbers, this species is regarded as vulnerable. Under the U.S. Fish and Wildlife Service, Tyhplichthys subterraneus is listed as a “species of concern,” however there have been no federal conservation plans for the Southern cavefish. It is classified as “vulnerable” by the World Conservation Monitoring Center. However, many caves are protected by various governmental regulations. Its protection status in the Southeast is as follows: Alabama: threatened, protected; Arkansas: Inventory Element; Georgia: Rare; Indiana: Endangered; Kentucky: Special concern; Missouri: Watch list; Oklahoma: Extirpated; Tennessee: Deemed in need of management. There have been various species management plans constructed across different sites in the Southeast. In the Ozark region of Missouri, Arkansas, and Oklahoma surrounding Mark Twain National Forest, there have been certain measures of protection put into action. Several caves in these surrounding areas have prohibited human visitation or habitat alteration, however this is more in concern for the cave or spring habitats and not the fish species itself. Currently, there are no species specific management plans or activities concerning the Southern cavefish in this particular area. Other smaller organizations have monitored the cavefish populations, although there is no immediate danger to the population size.[16]

Management Recommendations

Due to the restrictions on accessing the habitat of Tyhplichthys subterraneus, it would be difficult to determine a general conservation plan for all the populations, and it has been difficult to manage in the past. However, due to the potential impacts that the detrimental activities listed above could have on this species, it would be advantageous to have a consistent monitoring plan to observe the conservation status. Preventative measures should be taken across the occupied areas with this species, which would help encourage population growth. A number of measures could be taken such as awareness and reduction of population, monitoring of sediment and groundwater runoff into cave pools, and prevention of cave degradation or habitat alteration. By protecting the Southern cavefish’s habitat and not allowing human intrusion, the species could greatly benefit from specific management plans accommodated to that particular habitat. However, due to very low population numbers, this species of fish should be seriously considered being given a federally protected status.[17] To monitor this specific species, diving in caves would be required. This can be problematic in determining population counts, due to these fish living in complete darkness and completely lacking pigment. By using bright dive lights and snorkeling gear, a population of cavefish could be accounted for by slowing moving through the water and tallying the number of fish observed. There is not a bountiful supply of cavefish habitats, therefore it would be difficult to obtain an overall population count. As accounted in scientific research papers on the populations of Southern cavefish, this visual method has proved to be the most lucrative in obtaining a population number. Although this method is widely used, underwater and bankside observations of fish could also be used as a survey method which can also approach the accuracy of more inclusive techniques. These techniques could be electrofishing or rotenone collections as well. The visual method, however, could prove inaccurate due to observers only seeing obvious individuals and not inconspicuous ones. It seems, though, that manually counting these fish has proven most effective because of their low population numbers in specific habitats.[17] Again, due to their unique environment, it is quite difficult to obtain and place the Southern cavefish in captivity. This would require a special dark aquarium that mimicked the settings of the cave from which they were obtained. This could also prove to be difficult due to cavefish residing at considerable depths within cave pools. To gain a reasonable sample, it would be most plausible to gather several members of this species from various caves and areas. This would make observing evolutionary characteristics more plausible. The fish would have to be collected after the spring season, due to water rising. This would more than likely be the most sensible time due to the spring being their brooding season. It would then be possible to monitor females that had reproduced and also new young that had just been reared. There are no particular species that prey on the Southern cavefish, therefore there is no alteration that should be provided in their habitat. The caves in which these species of fish live should definitely be protected. They are susceptible to human pollution and affects that could significantly alter their population quantity. By protecting their environments from degradation and change, the species can hopefully thrive and eventually be plentiful in these southeastern caves.
[edit] References

The 30-year recovery effort for the Ozark cavefish (Amblyopsis rosae): analysis of current distribution, population trends, and conservation status of this threatened species.[17]

How hydrogeology has shaped the ecology of Missouri's Ozark cavefish, Amblyopsis rosae, and southern cavefish, Typhlichthys subterraneus: insights on the sightless from understanding the underground.[14]

Status of the federally endangered Alabama cavefish, Speoplatyrhinus poulsoni (Amblyopsidae), in Key Cave and surrounding caves, Alabama.[16]

Morphological and physiological correlates of evolutionary reduction of metabolic rate among amblyopsid cave fishes.[15]

Southern cavefish.[13]

1. Graening, G. O.; Fenolio, D. B.; Niemiller, M. L., et al. The 30-year recovery effort for the Ozark cavefish (Amblyopsis rosae): analysis of current distribution, population trends, and conservation status of this threatened species. Environmental Biology of Fishes: 87:55-88. 2010.

2. Noltie, DB; Wicks, CM. How hydrogeology has shaped the ecology of Missouri's Ozark cavefish, Amblyopsis rosae, and southern cavefish, Typhlichthys subterraneus: insights on the sightless from understanding the underground. ENVIRONMENTAL BIOLOGY OF FISHES: 62: 171-194.2001.

3. Kuhajda, BR; Mayden, RL. Status of the federally endangered Alabama cavefish, Speoplatyrhinus poulsoni (Amblyopsidae), in Key Cave and surrounding caves, Alabama. ENVIRONMENTAL BIOLOGY OF FISHES: 62: 215-222. 2001.

4. Poulson, TL. Morphological and physiological correlates of evolutionary reduction of metabolic rate among amblyopsid cave fishes. ENVIRONMENTAL BIOLOGY OF FISHES: 62:239-249. 2001.

5. Ramsey, J.S.; Mount, R.H. Southern cavefish. Vertebrate animals of Alabama in need of special attention: 14-15. 1998.

References

1. ^ Charles Girard (1859). "Ichthyological notes". Proceedings of the Academy of Natural Sciences of Philadelphia 11: 56–68. http://www.biodiversitylibrary.org/item/84784#70.
2. ^ Carl H. Eigenmann (1905). "Divergence and convergence in fishes". Biological Bulletin 8 (2): 59–66. http://www.jstor.org/stable/1535853.
3. ^ Julian J. Lewis (2002). "Conservation assessment for southern cavefish (Typhlichthys subterraneus)" (PDF). United States Forest Service. http://www.fs.fed.us/r9/wildlife/tes/ca-overview/docs/invertebrate_Typhlichthys_subterraneus-SouthernCavefish.pdf.
4. ^ a b Loren P. Woods & Robert F. Inger (1957). "The cave, spring, and swamp fishes of the family Amblyopsidae of central and eastern United States". American Midland Naturalist 58 (1): 232–256. http://www.jstor.org/stable/2422371.
5. ^ Lynne R. Parenti (2006). "Typhlichthys eigenmanni Charlton, 1933, an available name for a blind cavefish (Teleostei: Amblyopsidae), differentiated on the basis of characters of the central nervous system" (PDF). Zootaxa 1374: 55–59. http://www.mapress.com/zootaxa/2006f/zt01374p059.pdf.
6. ^ John E. Cooper & David P. Beiter (1972). "The southern cavefish, Typhlichthys subterraneus (Pisces, Amblyopsidae), in the eastern Mississippian Plateau of Kentucky". Copeia 1972: 879–881. http://www.jstor.org/stable/1442755.
7. ^ John E. Cooper & Antony Iles (1971). "The Southern cavefish Typhlichthys subterraneus at the southeastern periphery of its range". Bulletin of the National Speleological Society 33: 45–49.
8. ^ Thomas L. Poulson (2001). "Morphological and physiological correlates of evolutionary reduction of metabolic rate among amblyopsid cavefishes". Environmental Biology of Fishes 62 (1–3): 239–249. doi:10.1023/A:1011821107820.
9. ^ Bernard R. Kuhajda & Richard L. Mayden (2001). "Status of the federally endangered Alabama cavefish, Speoplatyrhinus poulsoni (Amblyopsidae), in Key Cave and surrounding caves, Alabama". Environmental Biology of Fishes 62 (1–3): 215–222. doi:10.1023/A:1011817023749.
10. ^ World Conservation Monitoring Centre (1996). Typhlichthys subterraneus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2.3. Downloaded on October 10, 2010.
11. ^ Douglas B. Noltie and Carol M. Wicks (2001). "How hydrogeology has shaped the ecology of Missouri's Ozark cavefish, Amblyopsis rosae, and southern cavefish Typhlichthys subterraneus: insights on the sightless from understanding the underground". Environmental Biology of Fishes 62 (1–3): 171–194. doi:10.1023/A:1011815806589.
12. ^ Gary O. Graening, Danté B. Fenolio, Matthew L. Niemiller, Arthur V. Brown & Jonathan B. Beard (2010). "The 30-year recovery effort for the Ozark cavefish (Amblyopsis rosae): Analysis of current distribution, population trends, and conservation status of this threatened species". Environmental Biology of Fishes 87 (1): 55–88. doi:10.1007/s10641-009-9568-2.
13. ^ a b c Ramsey, J.S.; Mount, R.H. Southern cavefish. Vertebrate animals of Alabama in need of special attention: 14-15. 1998.
14. ^ a b Noltie, DB; Wicks, CM. How hydrogeology has shaped the ecology of Missouri's Ozark cavefish, Amblyopsis rosae, and southern cavefish, Typhlichthys subterraneus: insights on the sightless from understanding the underground. ENVIRONMENTAL BIOLOGY OF FISHES: 62: 171-194.2001.
15. ^ a b Poulson, TL. Morphological and physiological correlates of evolutionary reduction of metabolic rate among amblyopsid cave fishes. ENVIRONMENTAL BIOLOGY OF FISHES: 62:239-249. 2001.
16. ^ a b Kuhajda, BR; Mayden, RL. Status of the federally endangered Alabama cavefish, Speoplatyrhinus poulsoni (Amblyopsidae), in Key Cave and surrounding caves, Alabama. ENVIRONMENTAL BIOLOGY OF FISHES: 62: 215-222. 2001.
17. ^ a b c Graening, G. O.; Fenolio, D. B.; Niemiller, M. L., et al. The 30-year recovery effort for the Ozark cavefish (Amblyopsis rosae): analysis of current distribution, population trends, and conservation status of this threatened species. Environmental Biology of Fishes: 87:55-88. 2010.