Slackwater darter (Etheostoma boschungi)

Description

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Slackwater darter fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Slackwater darter description

The North American darters are a diverse group of around 145 freshwater species in the Percidae, or perch family. Adapted to a bottom-dwelling lifestyle, these fish dart between the sanctuary of large stones, a behaviour that has earned the darters their common name. The body is deep and slender, with two separate dorsal fins and a sharp flap of skin covering the gills, but unlike other teleosts, the darters lack a swim bladder, a gas-filled sac typically used to regulate buoyancy ⁽³⁾. The somewhat drab-coloured slackwater darter is distinguished by a conspicuous vertical bar below the eye, and three saddle-shaped dark brown or blue-black patches that contrast with the brownish body. The male is similar to the female, but may have slightly more intense yellow and orange spotting around the base of the tail ⁽⁴⁾.

Size

Length: c. 4.6 cm ⁽²⁾

Maximum length: 7.8 cm ⁽²⁾

Slackwater darter biology

The slackwater darter feeds on a variety of invertebrates, including larval insects, limpets and isopods ^{(2) (5)}. Arriving at the breeding grounds in February, reproduction in the slackwater darter is highly dependant on heavy rainfall flooding breeding pools, as well as water temperature, which must be at least 14 degrees Celsius before spawning takes place ^{(4) (5)}. Fertilised eggs are laid on clumps of plants and aggressively defended by the male parent ^{(5) (6)}. Once hatched, the juvenile fish grow rapidly, doubling in size between April and June and leaving the breeding areas around May. A short-lived species, the slackwater darter reaches maturity at two years of age, with a life expectancy of only three years ⁽⁴⁾.

Slackwater darter range

The slackwater darter is endemic to the States of Alabama and Tennessee in the south-east of the United States. It is found around the middle Tennessee River drainage, occupying upper Shoal Creek, Swan Creek, Cypress Creek and the Flint and Buffalo Rivers ^{(2) (5)}.

Slackwater darter habitat

Inhabiting creeks and small rivers, the slackwater darter is typically found in slow-moving areas with gravel bottoms, no more than twelve metres wide and two metres deep. As a bottom-dwelling species it prefers areas with an accumulation of leaves and detritus, often with dense growths of filamentous algae, and is more tolerant of low levels of oxygen than other, related species ^{(2) (5)}. During the breeding season the slackwater darter will migrate to shallow spawning pools of four to ten centimetres depth, often traversing rapids and swifter streams along the way ⁽⁵⁾.

Slackwater darter status

Classified as Endangered (EN) on the IUCN Red List ⁽¹⁾.

Slackwater darter threats

With an extremely restricted range and a dependency upon areas with adjacent breeding and non-breeding sites, the slackwater darter is extremely vulnerable to any detrimental changes to its habitat. Unfortunately, urbanisation and agricultural activities are increasingly encroaching upon the species’ habitat and, consequently, the species’ habitat has dwindled, and the population has declined ⁽⁴⁾. The principle agent behind this decline is the extraction of ground water for agriculture and human consumption causing breeding areas to dry up. Streams have also been dammed to form fish-farm ponds, while pollutants seeping into the water table from septic tanks and sewer pipelines continue to degrade this rare species’ habitat ^{(4) (5)}. These threats are compounded by the species’ short life span as two consecutive poor breeding seasons could wipe out a substantial portion of the remaining population ^{(4) (6)}.

Slackwater darter conservation

The future of the slackwater darter is very much dependant on the careful management of its habitat ⁽⁴⁾. The conservation objectives for this Endangered species are set out in a detailed recovery plan, with the protection of both breeding and non-breeding habitat a key priority ⁽⁶⁾. Monitoring of water quality and surveys of population trends will also be required if the slackwater darter is to be saved ⁽⁴⁾.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For more information on the slackwater darter, see:

• U.S. Fish and Wildlife Service Species Account:
  http://www.fws.gov/cookeville/docs/endspec/slkdrtsa.html

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Glossary

Algae

Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.

Detritus

Litter formed from fragments of dead material.

Dorsal fin

The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Fertilisation

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Invertebrates

Animals with no backbone, such as insects, crustaceans, worms, molluscs, spiders, cnidarians (jellyfish, corals, sea anemones), echinoderms, and others.

Isopods

A diverse group of crustaceans, with flattened, segmented bodies, that includes pill bugs and woodlice.

Larval

Of the stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.

Spawning

The production or depositing of large quantities of eggs in water.

Teleost

Fish with a bony skeleton as opposed to cartilaginous fish (elasmobranchs).

References

1. IUCN Red List (April, 2010)
   http://www.iucnredlist.org/
2. FishBase (April, 2010)
   http://www.fishbase.org/summary/SpeciesSummary.php?id=3404
3. Campbell, A. and Dawes, J. (2004) Encyclopedia of Underwater Life. Oxford University Press, Oxford.
4. U.S. Fish and Wildlife Service Species Account (April, 2010)
   http://www.fws.gov/cookeville/docs/endspec/slkdrtsa.html
5. NatureServe Explorer (April, 2010)
   http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Etheostoma+boschungi
6. Boschung, H. (1984) Recovery Plan for the Slackwater Darter Etheostoma boschungi. U.S. Fish and Wildlife Service, Atlanta, Georgia.