Etheostoma lemniscatum

From Wikipedia, the free encyclopedia
Tuxedo darter
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Percidae
Genus: Etheostoma
Species: E. lemniscatum
Binomial name
Etheostoma lemniscatum
Blanton, 2008

The common name of Etheostoma lemniscatum is the tuxedo darter. It is one of the 324 fish species found in Tennessee.

Introduction:

Etheostoma lemniscatum is commonly known as the tuxedo darter. It is an extremely rare and endangered species that was only described four years ago. It was originally considered a duskytail darter (Etheostoma percnurum) but that species was determined a species complex in 2008 by R.E. Blanton and R.E. Jenkins (Davis 2010). E. lemniscatum is found in the Southeast United States in the Cumberland River. More specifically it is found in just a few locations in the Big South Fork portion of the river, which flows from north-central Tennessee to McCreary County, Kentucky (Encyclopedia of Life 2012). This region is protected by the National Park Service and called the Big South Fork National River and Recreation Area (National Park Service 2012). It is visually distinguished from other species of the E. percnurum complex by a more posterior anal fin (FishBase Consortium 2012). As in many aquatic species of the Southeast United States, the tuxedo darter is highly susceptible to sediment changes due to agricultural practices (Richter et al. 1997). E. lemniscatum requires efficient monitoring and management to preserve and prepare for the possible extirpation of the rare species. More knowledge can lead to a higher success rate in management and protection. Possible management strategies include but are not limited to captive breeding and reintroduction efforts that have proven successful in other darter species such as the closely related E. percnurum (Schute 2005) The infancy of E. lemniscatum is the driving force behind its research and only time can determine the status of the species.

Geographic Distribution:

Originally Etheostoma lemniscatum, then E. percnurum, was only reported in one location of the Big South Fork River. Prior to 1995 the mouth of Station Camp Creek in Scott County, Tennessee contained the only known tuxedo darter population. However, in 2000 D.J. Eisenhour and B.M. Burr discovered six additional sites spanning nineteen kilometers from Station Camp Creek (the original site) to Bear Creek in McCreary County, Kentucky. They estimated the population at 300 to 600 individuals. There are two more sites upstream that have been discovered but data has yet to be published. The Cumberland River is the primary drainage of the Cumberland Plateau, which sits between the Highland Rim to the west and the Southern Appalachian Mountains. The plateau contains well-drained soil that is acidic and lacks fertility. The river has eroded through a sandstone crust to its limestone base. The area has a history of industrial and agricultural practices, such as coal mining, that have reduced habitat for all wildlife. However, the region is now protected by the Big South Fork National River and Recreation Area (BSFNRRA) (Davis 2010).

Ecology:

Etheostoma lemniscatum is a benthic species with cryptic coloration and a lifespan only one to two years that do not venture far from their birthplace (Schute 2005). As a part of the E. percnurum species complex, which is in the subgenus Catonotus, is known to cluster its eggs. The complex is unique within the subgenus because its species prefer larger streams and moderately large rivers. The tuxedo darter is an insectivore feeding on microcrustaceans and chironimid larvae. It may also feed on heptageniid nymphs on the underside of rocks. They become sexually mature when they are greater than one year old and at least 39mm long (Davis 2010). Research on the citico darter (Etheostoma sitikuense), another member of the duskytail complex, has shown that it can produce five to seven clutches per year with clutch sizes recorded up to 101 eggs. The citico darter spawns at water temperatures between 17 and 24°C (Schute 2005). The tuxedo darter is known to spawn underneath slabrocks or boulders. E. lemniscatum prefers river sections that are 23.3 to 61.3 meters wide and 39.2 to 89.2 centimeters deep. Common substrate of the species is slabrock, cobble, and boulders where they build nests up to 50 meters upstream (Davis 2010) which contain the eggs of one or more females but are guarded by a single male (Schute 2005).

Life History:

As mentioned earlier, Etheostoma lemniscatum was known as Etheostoma percnurum prior to 2008. E. percnurum was first recorded in the Cumberland River in 1976. The four separate populations, now four different species, were listed as federally endangered in April, 1993. In describing the E. percnurum species complex Blanton and Jenkins claim that, “populations of the former duskytail darter were geographically isolated, and genetic divergence was theorized to have occurred, resulting in distinct differences among populations (Davis 2010).” Therefore, the unique morphology and ecology of E. lemniscatum is an important aspect to preserving the diversity within the E. percnurum species complex. As stated in the previous section, the Big South Fork region has a history of threatening agricultural, industrial, and environmental practices. Logging and coal mining dominated the region in the early 1900’s. However, the BSFNRRA was created in 1974 by the National Park Service and became the first form of protection for the then unknown tuxedo darter (Davis 2010). The purpose for creating the BSFNRRA as stated by the National Park Service’s website is, “conserving and interpreting an area containing unique cultural, historic, geologic, fish and wildlife, archaeologic, scenic and recreational values, preserving as a natural free-flowing stream the Big South Fork of the Cumberland River, major portions of its Clear Fork and New river stems, and portions of their various tributaries for the benefit and enjoyment of present and future generations, the preservation of the natural integrity of the scenic gorges and valleys and the development of the area’s potential for healthful outdoor recreation.”

Current Management:

The National Park Service, with preservation of new and rare species in mind, advocates the creation of monitoring programs for these species in response to declining biodiversity worldwide. E. lemniscatum fits the criteria for such programs and thus the National Park Service has proposed programs for the rare, imperiled darter. The Southeast United States is rich with biodiversity especially in the Cumberland and Appalachian mountain regions. Consequently, the area places preservation of biodiversity on high priority (Davis 2010). However, some preservation practices such as captive propagation (raising populations of rare species with the intention of reintroduction to native ranges should extirpation occur) are new to the region and not commonly supported by federal fisheries programs (Schute 2005). Therefore, private enterprises such as Conservation Fisheries inc. (CFI) are charged with the duty. CFI reports that there is no captive propagation program for the tuxedo darter, or are there any plans to create one. In 2010, Jonathan G. Davis—a graduate student at Tennessee Tech University—published a dissertation examining the protocols for a long-term monitoring program for the tuxedo darter and the spotfin chub. “The research goal was to construct statistically valid and tested monitoring protocols for both species that are applicable to similar rare fishes (Davis 2010).” Monitoring practices tested were simple random sampling, Adaptive Cluster Sampling (ACS), and underwater observation via line-transect swimming. While simple random sampling proved to be the most efficient sampling method for E. lemniscatum, ACS is a new sampling design and Davis’s testing of it may prove vital for other rare species. While ACS may be able to “identify areas of high abundance” of rare species, it poses challenges in modification and field implementation as well as other challenges (Davis 2010).

Management Recommendation:

David Etnier, who discussed our ability to detect rare species in a 1994 publication, “suggested that increased sampling efforts, especially for species that normally exist at low population densities, would increase our ability to determine whether a fish population has become extirpated or whether it simply exists at low levels (Schute 2005).” In the case of the tuxedo darter underwater observation is the ideal monitoring program primarily because it is less invasive than other programs (Davis 2010). Environmental, industrial, and agricultural threats to Etheostoma lemniscatum must continue to be managed to prevent extirpation of the darter and other rare species (Richter 1996). Once able captive propagation programs are necessary if extirpation should occur so that reintroduction efforts could follow. However, more federal support is needed. The probability of reintroduction success is high due to the successful reintroduction of another duskytail complex species (Schute 2005). The duskytail darter, along with other endangered species, was extirpated from Abrams Creek in Blount County, Tennessee due to the closing of Chilhowee Dam on the Little Tennessee River and ichthyocides meant to enhance trout fisheries. Using domestic and wild-spawned eggs, Conservation Fisheries inc. was successful in reintroducing Etheostoma percnurum (later recognized as E. sitikuense) from Citico Creek to Abrams Creek. After ten years of annual reintroduction the project determined survivorship at 49%. That percentage was higher for the wild-spawned egg populations (Schute 2005). If captive propagation and reintroduction of E. lemniscatum is deemed necessary, a model of the E. sitikuense project could be used and modified to primarily use wild-spawned eggs.

References

  • Davis, Johnathan G., “Development of Long-Term Monitoring Protocols for two Rare Fishes, the Tuxedo Darter and the Spotfin Chub, in Tennessee.” Ph.D. Dissertation, Tennessee Technological University, Cookeville, Tennessee. (2010)
  • Davis, Johnathan G., and Cook, S. B., "Habitat Use of the Tuxedo Darter (Etheostoma lemniscatum) at Macrohabitat and Microhabitat Spatial Scales." Journal of Freshwater Ecology 25(2011): 321-330
  • Davis, Johnathan G., Smith, David D., and Cook, S. B., "Testing the Utility of an Adaptive Cluster Sampling Method for Monitoring a rare and imperiled Darter." North American Journal of Fisheries Management 31(2011): 1123-1132
  • Grossman, Gary D., Ratajczak, Jr., Robert E., Crawford, Maurice, and Freeman, Mary C., “Assemblage Organization in Stream Fishes: Effects of Environmental Variation and Interspecific Interactions.” Ecological Monographs 68 (1998): 395-420
  • Richter, Brian D., Braun, David P., Mendelson, Michael A., and Master, Lawrence L., “Threats to Imperiled Freshwater Fauna.” Conservation Biology 11 (1997): 1081-1093
  • Shute, J. R., Rakes, P. L., and Shute, P. W., "Reintroduction of Four Imperiled Fishes in Abrams Creek, Tennessee." Southeastern Naturalist 4(1)(2005): 93-110
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