|Scientific Name:||Etheostoma ditrema|
|Species Authority:||Ramsey & Suttkus, 1965|
|Taxonomic Notes:||This species exhibits substantial biochemical and morphological variation; as many as three forms may soon receive formal taxonomic recognition (see Boschung and Mayden 2004).|
|Red List Category & Criteria:||Endangered B2ab(ii,iii,iv,v) ver 3.1|
|Reviewer/s:||Smith, K. & Darwall, W.R.T.|
|Facilitator/s:||Hammerson, G.A. & Ormes, M.|
This species is listed as Endangered because it area of occupancy may be less than 500 sq km, distribution is severely fragmented, number of locations (with respect to threats) may not exceed 5, and habitat quality/quantity and probably area of occupancy, number of subpopulations, and adult population size are subject to ongoing declines.
|Range Description:||The range encompasses the upper and middle Coosa River system in the Ridge and Valley Province above the Fall Line in northeastern Alabama, northwestern Georgia, and extreme southeastern Tennessee (Etnier and Starnes 1993, Boschung and Mayden 2004). This range pertains to the Etheostoma ditrema complex, which eventually may be split into multiple taxa. Populations are "very fractionated" (Boschung and Mayden 2004)|
|Range Map:||Click here to open the map viewer and explore range.|
This species is represented by a small number of occurrences (subpopulations). Boschung and Mayden (2004) mapped 32 collection sites in Alabama; many of these are closely adjacent within a single stream; probably at least 15 are distinct occurrences.
Adult population size is unknown. This species is locally abundant in spring habitat (Etnier and Starnes 1993), but overall it is not very common. Page and Burr (2011) regarded it as rare and highly localized.
Etnier and Starnes (1993) noted that several populations "have doubtless been eliminated by habitat alterations."
Area of occupancy, number of subpopulations, and population size may be declining, but the rate of decline probably is less than 30% over three generations or 10 years. Status in Alabama has not improved over the past several decades (Boschung and Mayden 2004).
|Habitat and Ecology:||This darter occurs among aquatic vegetation or coarse organic debris in limestone springs and slow spring runs at depths of 1 meter or less; it is most numerous in vegetation-filled spring ponds with growths of aquatic mosses, watercress, and milfoil; it may perch on clumps of vegetation well off the bottom (Page 1983, Kuehne and Barbour 1983, Utter 1984, Etnier and Starnes 1993, Catchings 1994, B. R. Kuhajda pers. comm. 1998). Water temperature of the habitat tends to be fairly static (13-18 °C).|
|Major Threat(s):||Several populations have doubtless been eliminated by habitat alterations (Etnier and Starnes 1993). Spring habitats are rapidly being altered through use of chemicals to eliminate native plants and animals so that the springs can be used for "home water gardens," fishing ponds (with introduced fishes), and drinking water sources (Boschung and Mayden 2004). Stream habitats have been degraded by groundwater depletion (loss of spring influence) and massive siltation and pollution associated with urbanization (e.g., Birmingham, Alabama) (Boschung and Mayden 2004). Large concrete structures pose a barrier to dispersal (B. R. Kuhajda pers. comm. 1998), as do impoundments. Warm summer-month temperatures in surrounding spring waters are also thought to preclude dispersal (B. R. Kuhajda pers. comm. 1998). This species is of conservation concern in all three states in which it occurs.|
There are no known species-specific conservation measures in place for Etheostoma ditrema, however, it was previously assessed as Vulnerable (criterion D2) on the 1996 IUCN Red List version 2.3.
Further research is needed to clarify the taxonomic status of this species. Conservation measures need to be taken to protect key recharge sources for springs in which this species occurs, with additional efforts to alleviate pollution and other pressures on this species habitat. Monitoring of the population numbers and habitat status of this species is needed.
|Citation:||NatureServe 2013. Etheostoma ditrema. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 March 2014.|
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