Bluebreast darter

Bluebreast darter
Conservation status
Least Concern  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Percidae
Genus:	Etheostoma
Species:	E. camurum
Binomial name
Etheostoma camurum (Cope, 1870)

The bluebreast darter, Etheostoma camurum, is a member of the subgenus Nothonotus and has a close phylogenetic relationship to E. chlorobranchium.^[1][2]

Introduction

The bluebreast darter is small in size, rarely reaching longer than three inches. The snout is blunt, more rounded than other darters, and its gill covers do not bridge the breast. It is a colorful fish, predominantly olive green with a broad, lighter band that runs adjacent to the dark fringe of the second dorsal and anal fins, reaching the base of the caudal fin. During breeding, though, males tend to be very colorful, usually with orange-tinted dorsal fins, dark red spots along the sides, and the descriptive bright blue breast from which it gets its name.^[3] The species is commonly found in clean-flowing, medium to large rivers with high benthic current velocity and an abundance of sedimentary gravel. Currently, E. camurum is listed as imperiled or higher in seven eastern US states.^[3]

Geographic distribution

This darter’s range covers most of the Eastern Highlands in the US, extending latitudinally from Tennessee to New York and longitudinally from West Virginia to Illinois.^[3] Populations have historically inhabited streams in the Ohio River drainage, the Alleghany River basin (NY and PA), the Wabash River basin (IN and IL), and the Tennessee River basin (TN and NC). Its habitats in these regions have patchy distributions as a result of habitat degradation and fragmentation following the post-Pleistocene dispersal.^[4] In New York, its conservation status will likely be raised to ‘endangered’ following its severe population decline.^[3] Likely causes of decline have been linked to physical effects, such as impoundments, and chemical effects, such as agriculture drainage runoff, to the darter’s natural habitat.^[5] In addition, its specialized habitat makes it highly vulnerable to environmental and anthropogenic pressures.^[5] As a result of these pressures, populations have become increasingly isolated and restricted to moderate to large streams with turbid flow and high water quality.^[6]

Ecology

This darter's habitat is highly specialized and dependent on water quality and stream velocity. These habitats are located in eddies and riffles behind boulders in large to moderately sized, gravel-bottomed streams.^[7] More specifically, populations often exist in the benthopelagic regions in the water column, ranging from depths of 10 to 30 cm.^[4] Its diet typically consists of insect (e.g. dipteran) larvae^[8] due mostly to morphological restraints, including an average gape size of around 8 mm.^[4] Temperature ranges year-round are unknown, but spawning water temperatures range from 10 to 24°C.^[7] Predators for this particular species are not clear, but data on a sister species, the rainbow darter (E. caeruleum), suggest larger freshwater fish, such as burbots (Lota lota), stonecats (Noturus flavus), and smallmouth bass (Micropterus dolomieu) have been known to prey on darters.^[9] Although data are largely unknown, predation effects on the bluebreast darter are thought to be relatively low due to the small, localized habitats of this species in riffles and eddies behind boulders that prevent larger pelagic fish from exploiting them.^[10] Typical anthropogenic effects detrimental to their ecology include strip mining, mica shale siltation, impoundments (dams), and agricultural drainage runoff.^[4]

Life history

The breeding season for this fish peaks from mid-May through June for many habitats.^[11] During this time, nuptial males develop their characteristic blue breast and brick-red spotting on their sides.^[7] Spawning begins when the males become territorial and seek out eddies and riffles in the head streams. Females soon follow and decide both the location of the reproductive event and the individual mates. Mating is stimulated once the female begins a ritual that involves a sequence of erratic darts that are then mimicked by the male.^[7] Once this occurs, the female will bury herself into a gravel shoal, nearly level with the bottom of the streambed. Then the male will approach from above and a series of vibrations, lasting no longer than 10 sec at a time, will signify each reproductive event.^[7] This is known to occur at least three times per reproductive event. About 100 eggs are laid during this time.^[7] The males then stay behind to guard the eggs during a seven- to 10-day incubation period, after which parental care ceases.^[12] Data on clutch sizes are unclear for E. camurum, but studies on sister species, like the fantail darter (E. flabellare), suggest numbers range from 33 to 96 individuals.^[13] Sexual maturity for the juveniles is reached within the first year for most species within the genus,^[14] and the typical life span for E. camurum is three years.^[4] Anthropogenic changes in water velocity can affect its breeding cycle . Also, increased turbidity due to stormwater runoff in streams can be detrimental to egg clusters buried in the gravel streambed,^[5] often causing eggs to become detached and free flowing, downstream and out of the protective care of the male.

Current management

The incentive for conservation action of this species stems from its role as an indicator species;^[4] spotty distributions and specialized habitats are of particular concern. Specifically, small populations, isolated by physical impoundments, have an increased risk for a host of genetic problems, including inbreeding effects, genetic drift, and loss of heterozygocity. Anthropogenic effects from siltation buildup, impoundments, strip mining, dredging, agriculture, and roadway runoff have all had detrimental impacts on its breeding and habitat.^[5][11] E. camurum is not currently placed on IUCN’s Red list, but NatureServe ^[11] recommends close monitoring of its habitat and water quality. NatureServe has currently listed E. camurum to be ‘critically imperiled’ in Illinois, Alabama, Indiana, and New York, ‘imperiled’ in Ohio, Pennsylvania, and Virginia, ‘vulnerable’ in West Virginia, and ‘apparently secure’ in Tennessee and Kentucky. Recent efforts in the Ohio River drainage have revived populations back to historical numbers. This has been achieved by attempts to improve water quality in these regions.^[12] Studies suggest increased awareness and close monitoring of streams and waterways are needed,^[11] suggesting most of the threats to the species well-being are human related. There is little information for threats caused by predation, invasive species competition, or overfishing.

Management recommendations

Because of its isolated and specialized habitat, E. camurum is of particular ecological concern.^[4] Anthropogenic effects are thought to be the cause of most population decline, as increased human development has been detrimental to both habitat and breeding.^[7] Recent studies suggest a combined effort to closely monitor physical aspects of E. camurum habitats, such as water turbidity and flow rate, and water chemistry, such as nitrates and phosphorus concentrations, which occur from agriculture runoff.^[5] This can be achieved by increased awareness and strict management of the watershed in these regions.^[3] To achieve this, more complete data on regional populations and population densities are needed. Efforts to collect and sample existing populations will enable conservation policy to be more direct and efficient. Although its habitat is largely localized and isolated, studies have detailed methods for its capture. This includes disrupting eddies and riffles by moving the boulders and large rocks in streams, followed by seining.^[15] Additionally, E. camurum has been linked to spawning of the endangered tan riffleshell (Epioblasma florentina walkeri). Studies have shown the riffelshell larvae attach to E. camurum during maturation.^[10] This is an example of how declines in darter populations could signal cascading effects for other species in the ecosystem. Complete protection of these waterways would ensure both adequate flow velocity and high water quality, but this may not be feasible in many areas. Close monitoring and detailed analysis on population data will ensure effective conservation efforts and keep the species' populations near historic levels.

References

• Eisenhour, D.J. 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.
• Felbaum, M., et al. 1995. Endangered and Threatened Species of Pennsylvania. Wild Resource Conservation Fund.
• Hatch, J.T & Paulson, N. 2011. Rainbow Darter. Bell Museum of Natural History.http://www.pca.state.mn.us/index.php/living-green/living-green-citizen/for-kids/creature-feature/rainbow-darter.html?menuid=819&redirect=1.
• Heins, D.C. 2001. Variation in Clutch Size and Ovum Size of the Snubnose Darter (Etheostoma simoterum), from Two Populations in Tennessee. American Midland Naturalist, 145, 74-79.
• NatureServe. 2011. Etheostoma Camurum. NatureServe Explorer: An online encyclopedia of life. http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Etheostoma%20camurum.
• Mount, D.I. 1959. Spawning Behavior of the Bluebreast Darter, Etheostoma camurum (Cope). Copeia, 3, 240-243.
• Mountz, V., Hathaway, M., Smith, L., & Ervin, V. eds. 2010. Darter: Jewels of the Stream. Wild Ohio Magazine,Spring ed., 7.
• Smith, P.W. 1979. Fishes of Illinois. University of Illinois Press, 3, 280.
• Shiels, A.L. 1997. Pennsylvania's Dynamic Darters. Pennsylvania Fish & Boat Commission. http://www.fish.state.pa.us/education/catalog/darters.html.
• Smiley, P.C. Jr., Gillespie, R.B., King, K.W., & Huang, C.H.2008. Contribution of habitat and water quality to the integrity of fish communities in agriculture drainage ditches. Journal of Soil and Water Conservation. 63: 218-219.
• Stauffer, J.R. 1995. Fishes of West Virginia. Academy of Natural Sciences, 1, 311.
• Tiemann, J.S. 2008. Distribution and life history characteristics of the state-endangered Bluebreast darter Etheostoma camurum (cope) in Illinois. Transactions of the Illinois State Academy of Science, 3-4, 235-246.
• Werner, R.G. 2004. Freshwater fishes of the Northeastern United States: A Field Guide. Syracuse University Press, 1, 255.
• Zorach, T. 1972. Systematics of the Percid Fishes, Etheostoma camurum and E. chlorobranchium New Species, with a Discussion of the Subgenus Nothonotus. Copeia, 3, 427-447.