|Scientific Name:||Etheostoma rubrum|
|Species Authority:||Raney & Suttkus, 1966|
|Red List Category & Criteria:||Endangered B1ab(iii)+2ab(iii) 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 occurrence is less than 1,000 sq km, area of occupancy is around 100 sq km, number of locations is four, distribution is not severely fragmented, and habitat quality is declining.
|Range Description:||This species' range is restricted to Bayou Pierre and its tributaries, including White Oak Creek, Foster Creek, and Turkey Creek (see maps in Ross et al. 1992, 2001; Page and Burr 2011). Bayou Pierre is a tributary of the Mississippi River in western Mississippi. Densities are highest in the upper parts of the Bayou Pierre system, but the species also persists as apparently self-sustaining populations in the middle and lower reaches of Bayou Pierre, at least down to its confluence with Little Bayou Pierre (Slack et al. 2004).
Bayou Pierre watershed encompasses about 2,500 square kilometers, 700 square kilometers of which is occupied by Etheostoma rubrum (Slack et al. 2010).
|Range Map:||Click here to open the map viewer and explore range.|
This species is represented by a small number of occurrences in four streams (here regarded as four locations) (see map in Slack et al. 2010).
The total adult population size is unknown but presumably exceeds 10,000. Ross et al. (2001) collected 1,108 bayou darters during 1986-1994; density in riffles averaged around one Bayou Darter per square meter.
Density was stable in the 1980s and 1990s, but distribution shifted upstream due to ongoing geomorphic changes (headcutting) (Ross et al. 2001).
|Habitat and Ecology:||
This darter inhabits fast rocky riffles of shallow, meandering creeks and small to medium rivers (Page and Burr 2011). It prefers stable, moderately swift riffles and runs over large gravel and rock, and it seldom occurs over shifting substrates. Adults are most commonly collected near heads of gravel riffles in water less than 15-30 centimetres deep. Upstream distribution is apparently limited by low water flow in summer and fall (USFWS 1990).
Ross et al. (1990, 1992) characterized the habitat as mid-reach (typically third to fourth order) stream sections, with swift (mean 79 cm/sec), shallow water and firm coarse substrates (mean particle size 16-32 mm); in winter, Bayou Darters were associated with logs, cobble, and boulders, which may comprise important refugia during periods of high stream flow.
Bayou Darters apparently are egg buriers that probably use fine gravel or coarse sand (Ross and Wilkins 1993). Some larvae drift from spawning sites (Slack et al. 2004).
The major threats to this species are human-induced alterations of its habitat: floodplain/channel modification and farming-silviculture (may cause erosion and siltation), petroleum exploration and transportation (threaten water quality), and gravel mining (USFWS 1990).
Habitat is undergoing rapid channel and bank erosion (Ross and Wilkins 1993, Ross et al. 2001). Factors responsible for rapid headcutting are downstream of currently affected reaches in Bayou Pierre and the Mississippi River; these potentially include natural meander cut-offs, channel avulsion, channelization, and instream gravel mining (Ross et al. 2001). The impact of these changes on the Bayou Darter are not well understood. Ross et al. (2001) found no evidence of a population decline, but Ross (2001) stated that the ongoing habitat alteration may be detrimental to the long-term survival of the species.
|Conservation Actions:||Actions needed (USFWS 1990): continue population and habitat monitoring programs; identify sources of habitat degradation; and protect darters and their habitat.|
|Citation:||NatureServe 2013. Etheostoma rubrum. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 31 July 2015.|
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