| Etheostoma camurum | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Percidae |
| Genus: | Etheostoma |
| Species: | E. camurum |
| Binomial name | |
| Etheostoma camurum (Cope, 1870) |
|
The common name of Etheostoma camurum is the bluebreast darter. It is one of the 324 fish species found in Tennessee. It is a member of the subgenus Nothonotus and has a close phylogenetic relationship to E. chlorobranchium[1].
Contents |
The following is an introduction for a management plan for the Etheostoma camurum for Ichthyology (EEB 474) at The University of Tennessee, Knoxville. The E. camurum is a 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. The E. camurum 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. However, during breeding, 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 [2]. The species is commonly found in clean flowing, medium to large rivers with high benthic current velocity and an abundance of sedimentary gravel. Currently, the E. camurum is listed as imperiled or higher in seven eastern U.S states [2].
E. camurum’s range covers most of the Eastern Highlands in the U.S. extending latitudinally from Tennessee to New York and longitudinally from West Virginia to Illinois [2]. Populations have historically inhabited streams in the Ohio River drainage, the Alleghany River basin (NY & PA), the Wabash River basin (IN & IL), and the Tennessee River basin (TN & NC). E. camurum habitats in these regions have patchy distributions as a result habitat degradation and fragmentation following the post-Pleistocene dispersal [3]. In New York State, E. camurum’s conservation status will likely be raised to ‘endangered’ following severe population decline [2]. 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 [4]. In addition, E. camurum’s 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].
E. camurum’s habitat is highly specialized and dependent on water quality and stream velocity. These habitats are located in eddies and riffles behind boulders on 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 10cm to 30cm [8]. Its diet typically consists of insect larvae (e.g. dipteran larvae) [9] due mostly to morphological restraints, including an average gape size of around 8mm [10]. Temperature ranges for E. camurum year-round are unknown, however spawning water temperatures range from 10-24 °C [11]. Predators for this particular species are not clear, however data on the sister species, the rainbow darter (E. caeruleum), suggests larger freshwater fish like Burbots (Lota lota), Stonecats (Noturus flavus), and Small-mouth Bass (Micropterus dolomieu) have been known to prey on darters [12]. Although data is largely unknown, predation effects on E. camurum 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 [13]. Typical anthropogenic effects that are detrimental to E. camurum’s ecology include strip mining, mica shale siltation, impoundments (dams), and agricultural drainage runoff [14].
E. camurum’s breeding season peaks from mid-May through June for many habitats [15]. During this time, nuptial males develop their characteristic bluebreast and brick red spotting on their sides [16]. 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 [17]. 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 10sec at a time, will signify each reproductive event [18]. This is known to occur at least three times per reproductive event. Approximately one hundred eggs are laid during this time [19]. The males then stay behind to guard the eggs during a 7-10 day incubation period, after which time parental care ceases [20]. Data on clutch size is unclear for E. camurum, but studies on sister species, like the fantail darter (E. flabellare), suggest that numbers range from 33-96 individuals [21]. Sexual maturity for the juveniles is reached within the first year for most species within the genus [22] and the typical life span for E. camurum is three years [23]. Anthropogenic changes in water velocity can effect E. camurum’s breeding cycle . Also, Increased turbidity due to storm water runoff in streams can be detrimental to egg clusters buried in the gravel streambed [24] often causing eggs to become detached and free flowing, downstream and out of the protective care of the male.
E. camurum’s incentive for conservation action stems from its role as an indicator species [25]. Spotty distributions and specialized habitats are of particular concern for this species. 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 to E. camurum’s breeding and habitat [26] [27]. E. camurum is not currently placed on IUCN’s Red list, but NatureServe [28] 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 [29]. Studies suggest that increased awareness and close monitoring of streams and waterways are needed [30], suggesting most of the threats to the species wellbeing are human related. There is little data for threats caused by predation, invasive species competition, or over fishing.
Because of its isolated and specialized habitat, E. camurum is of particular ecological concern [31]. Anthropogenic effects are thought to be the cause of most population decline as increased human development has been detrimental to both E. camurum’s habitat and breeding [32]. 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 increased nitrates and phosphorus concentrations from agriculture runoff [33]. This can be achieved by increased awareness and strict management of the watershed in these regions [2]. 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 E. camurum’s habitat is largely localized and isolated, studies have detailed methods for their capture. This includes disrupting eddies and riffles by moving the boulders and large rocks in streams followed by seining [34]. Additionally, E. camurum has been linked to spawning of the endangered Tan Riffleshell (Epioblasma florentina walkeri). Studies have shown that Riffelshell larvae attach to the E. camurum during maturation [13]. 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, however this may not be feasible in many areas. Close monitoring and detailed analysis on population data will ensure effective conservation efforts and keep E. camurum’s populations near historic levels.