The greenfin darter (''Etheostoma chlorobranchium'') is a species of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, a darter from the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Etheostomatinae Etheosomatidae is a species rich subfamily of freshwater ray-finned fish, the members of which are commonly known as the darters. The subfamily is part of the family Percidae which also includes the perches, ruffes and pikeperches. The family i ...

, part of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Percidae The Percidae are a family of ray-finned fish, part of the order Perciformes, which are found in fresh and brackish waters of the Northern Hemisphere. The majority are Nearctic, but there are also Palearctic species. The family contains more than ...

, which also contains the

perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...

es, ruffes and pikeperches. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the eastern

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Geographic distribution

The greenfin darter is primarily restricted to the fast-flowing, mountainous streams and rivers of the upper Tennessee River drainage area, in North Carolina, Georgia, and Tennessee. The species' range stretches from the upper Holston and Watauga Rivers, south through the French Broad and Little Tennessee Rivers, and ultimately ends at the Hiwassee River.Etnier, D. A., & Starnes, W. C. (1993). Fishes of Tennessee (pp. 478–479). University of Tennessee press.

Ecology

The greenfin darter is a benthic

insectivore A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant that eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores wer ...

, feeding mainly on insect larvae in cold, high-elevation creeks and rivers. A study by Bryant'' et al.'' revealed the diet of the greenfin darter may be the most diverse in the genus, with some individuals' guts containing up to 15 different species of insects. Its predators are mainly larger freshwater fish, such as smallmouth bass (''Micropterus dolomieu'') and madtoms (genus ''Notorus''). Darters in general are important food sources for many fish.Kuehne, R., R. Barbour. 1983. The American Darters. Lexington, Kentucky: The University Press of Kentucky. Freshwater eels commonly consume adult darters, and suckerfish prey on their eggs. The species is relatively abundant, and has been found to hybridize with ''E. camurum'' and ''E. rufilineatum'', where ranges overlap. Like many other darter species, the greenfin has adapted morphologically to reduce drag and allow stationary positioning on the substrate even in the midst of fast-flowing riffles.Carlson, R.L and G.V. Lauder. 2010. Living on the Bottom: Kinematics of Benthic Station-Holding in Darter Fishes (Percidae: Etheostomatinae). Journal of Morphology (271): 25-35.

Life cycle

Spawning occurs from late May to early August. Females bury themselves in the substrate in areas protected from strong currents, and release eggs upon the arrival of a mate. The male may remain at the spawning site for several hours, guarding the eggs. Growth is extremely rapid, with juveniles reaching 45 mm in just a year. Mean length is 62 mm, with some individuals reaching as much as 110 mm. Lifespans can be up to five years. ''E. chlorobranchium'' is thought to be the largest species in the subgenus ''Nothonotus''.

Environmental status

''E. chlorobranchium'' has not been evaluated by the IUCN, although it is classified as state threatened in Georgia. However, the species is found and protected in the

Great Smoky Mountains National Park Great Smoky Mountains National Park is an American national park in the southeastern United States, with parts in North Carolina and Tennessee. The park straddles the ridgeline of the Great Smoky Mountains, part of the Blue Ridge Mountains, whi ...

and the Southern Appalachian Biosphere reserve. Greenfin populations are certainly vulnerable to siltation, water impoundment (or any change to water velocity), and agricultural runoff. A close relative, ''E. camurum'', has seen huge population declines due to anthropogenic environmental disturbances, and is listed as critically imperiled in several states.Smiley, P.C., R. B. Gillespie, K. W. King, and C. Huang. 2009. Management implications of the relationships between water chemistry and fishes within channelized headwater streams in the Midwestern United States. Ecohydrology (2): 294-302. Hybridization between ''E. chlorobranchium'', ''E. camurum'', and ''E. rufilineatum'' does not appear to be a threat to the species.Eisenhour, DJ. 1995. Systematics of Etheostoma camurum and E. chlorobranchium (Osteichthyes, Percidae) in the Tennessee and Cumberland River drainages with analysis of hybridization in the Nolichucky river system. Copeia 2:368-379. Additionally, climate change may force the greenfin into higher elevations, and into smaller streams. This will almost certainly lead to population declines. Because of its position as an important food source for larger fish in the Tennessee River drainage area, it is important for this species to be assessed and monitored in the future.

References

External links

Bio.utk.edu
{{Taxonbar, from=Q2044379 Etheostoma Fish described in 1972