|Scientific Name:||Chrosomus cumberlandensis|
|Species Authority:||(Starnes & Starnes 1978)|
Phoxinus cumberlandensis Starnes & Starnes, 1978
|Red List Category & Criteria:||Endangered B1ac(iii,iv)+2ac(iii,iv) ver 3.1|
|Reviewer(s):||Smith, K. & Darwall, W.R.T.|
|Facilitator/Compiler(s):||Hammerson, G.A. & Ormes, M.|
This species is listed as Endangered because its extent of occurrences is less than 5,000 sq km, area of occupancy probably is less than 500 sq km, distribution is severely fragmented, overall population likely is declining, and local subpopulations are subject to extreme fluctuations, including rapid extirpations.
|Range Description:||This species' range includes small tributaries in the Cumberland Plateau portion of the upper Cumberland River above Cumberland Falls and a few kilometres below (Etnier and Starnes 1993), in Pulaski, Laurel, McCreary, Whitley, Knox, Bell, Harlan, and Letcher counties in Kentucky, and Scott, Campbell, and Claiborne counties in Tennessee (USFWS 1988). The species also occurs in Cox Creek, a small tributary of the North Fork Powell River in Lee County, Virginia (though this population could turn out to be an undescribed species) (2001 Endangered Species Bulletin 25(3):39). Page and Burr (2011) did not mention Virginia in their range description.|
|Range Map:||Click here to open the map viewer and explore range.|
This species is represented by a large number of occurrences (subpopulations). At the time of federal listing, the species was known to occupy about 14 stream miles (23 kilometers) in 30 separate streams (USFWS 1987, 1988). Subsequently, Williams et al. (1989) reported that populations occurred in 35 isolated stream reaches totalling 27 kilometres. Extensive surveys in 1993 documented the presence of at least 27 more streams containing Blackside Dace (Eisenhour and Stange 1998). Subsequent surveys (see following) have found this dace in additional streams.
In Kentucky, the species is known from at least 91 streams; during a 1993-1994 survey the species was verified extant in 72 streams, but only 22 streams supported excellent or good populations; most populations were very small and near extirpation (Laudermilk data).
In Tennessee, this dace has been documented in at least a couple of dozen localities, but these may represent only a few metapopulations or population clusters (P. Shute pers. comm. 1997). Etnier and Starnes (1993) reported that only six small populations were then known to occur in Tennessee.
Populations of this species are relatively mobile; if extirpated they may recolonize in a short time, provided appropriate habitats for refugia and dispersal routes are available (P. Shute pers. comm. 1997).
Total adult population size is unknown but is probably at least several thousand. Most populations are small and consist of only a few individuals in short (0.1-1.0 kilometres) segments of suitable habitat (O'Bara 1990). The densest populations include an estimated 55-75 individuals per 100 square meters of stream (Starnes and Starnes 1981).
During a 1993-1994 survey in Kentucky, approximately 1,065 individuals were observed; many streams where this species is known to occur were not intensively surveyed; one intensively surveyed site produced over 500 individuals (Laudermilk data).
Historical distribution was probably much more continuous than at present, but the degree of decline is uncertain. Now, small populations are isolated from each other by extremely degraded habitat. The species has been extirpated from at least 10 streams (O'Bara 1990), and probably many others were extirpated before they could be discovered (Starnes and Starnes 1978).
Current trends are not well known, but area of occupancy, number of subpopulations, and population size appear to be declining or at least many subpopulations are vulnerable to extirpation. Many populations in Kentucky are extremely small or isolated and near extirpation (Laudermilk data), so the species is probably declining in that state. The species is believed to be stable in Tennessee, but it is susceptible to rapid fluctuations in population size and distribution (P. Shute pers. comm. 1997). Etnier and Starnes (1993) characterized the remaining populations in Tennessee as "all very localized and vulnerable to extirpation...." Many streams that formerly supported populations have been destroyed; status of populations has fluctuated greatly over the past decade (Shute et al. unpublished data).
|Habitat and Ecology:||This species inhabits small upland headwaters and creeks 2-5 meters wide where riffle and pool areas are about equal, and substrates are sand, sandstone, and shale (Burr and Warren 1986, Etnier and Starnes 1993). It occurs in pools with cover such as bedrock, rubble, undercut banks, or brush, and is generally associated with lush riparian vegetation, canopy cover greater than 70%, cool water, and unsilted conditions. The species can apparently recolonize areas when water quality or habitat conditions become more favourable if suitable dispersal corridors exist (Strange and Burr 1995). Blackside Dace exist as metapopulations (groups of local populations for which dispersal corridors are very important in the persistence of individual local populations) (Strange and Burr 1995).|
|Use and Trade:||This species is not utilized.|
|Major Threat(s):||Threatened status is due primarily to impacts of siltation from coal mining, silviculture, agriculture, and road construction, and impacts of unregulated acid mine drainage and impoundments; these factors still constitute a threat (USFWS 1987, 1988). Additional threats include channelization and non-point source pollution (Laudermilk 1995). The Southern Redbelly Dace (Phoxinus erythrogaster), a comparatively more recent (geologically) component of the upper Cumberland River basin fauna, is now present in many basin streams (Starnes 1981, Starnes and Starnes 1987). The Redbelly Dace is believed to have outcompeted and displaced Blackside Dace from some stream habitats where the water and habitat quality have been altered (i.e., stream bank modification, channel modification, and forest cover modification) to create warmer and more turbid conditions (Starnes 1981). Introductions of non-native predaceous fishes (e.g., Oncorhynchus mykiss) may have a negative effect on the remaining populations (Leftwich et al. 1995). Remaining populations are small and isolated from each other by extremely degraded habitat, and the exchange of genetic material among some of these populations is likely infrequent or nonexistent. If isolation continues, some of the smaller populations may have insufficient genetic variability to maintain long-term viability (USFWS 1988). Site visitation is not detrimental (P. Shute pers. comm. 1997). The species is regarded as very threatened in Tennessee (Peggy Shute pers. comm. 1997).|
This species appears to be intolerant of surface coal mining; these activities should be discontinued in dace-occupied basins (Eisenhour and Strange 1998). Wide riparian zones need to be maintained, land management practices that minimize siltation should be implemented (Eisenhour and Strange 1998).
Spawning protocols are being established (J. R. Shute and P. L. Rakes pers. comm., cited by Eisenhour and Stange 1998), in case reintroduction becomes necessary.
The minimum number of individuals needed for a viable population needs to be determined. Better information is needed on the extent genetic exchange occurring between small, isolated populations (Laudermilk). Analysis of stream habitat requirements would be useful in linking habitat use patterns to potential changes in land use within a watershed (Leftwich et al. 1995).
Continuous monitoring of known populations and nearby suitable habitat that could be colonized is needed to assess trends (Laudermilk).
|Citation:||NatureServe 2014. Chrosomus cumberlandensis. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 27 August 2015.|
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