Fusconaia cor 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Bivalvia Unionoida Unionidae

Scientific Name: Fusconaia cor (Conrad, 1834)
Common Name(s):
English Shiny Pigtoe
Fusconaia edgariana (I. Lea, 1840)
Taxonomic Notes: Ortmann (1918) determined Fusconia edgariana to be a junior synonym of Fusconaia cor. Campbell and Harris (2006) found this species to be closely related to Fusconaia cuneolus, but held it up as distinct.

A list of synonyms for this species can be found on The MUSSEL project web site (Graf and Cummings 2011).

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2ace ver 3.1
Year Published: 2012
Date Assessed: 2012-03-05
Assessor(s): Cummings, K. & Cordeiro, J.
Reviewer(s): Bohm, M., Collen, B. & Seddon, M.
Contributor(s): Richman, N., Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K., Collins, A., Offord, S. & Duncan, C.
Fusconaia cor has been assessed as Critically Endangered under criterion A2ace. The limited range of this species is becoming even more restricted (down to only five rivers, two of which may no longer be viable) due to changes in water quality from pollution and impoundments. Range declines have been significant (80%), and are likely to equate to at least 80% population reductions. Although the generation length is not known, the decline over 25-50 years is over 3 generation lengths using estimates from Haag and Rypel (2011). In addition, declines of around 80% in some parts of the species range have occurred since about 1999, thus estimated to be about 70% over a timeframe of 10 years (see Jones and Neves 2007, Hanlon et al. 2009, Eckert & Pinder 2008, Eckert et al. 2010). Surviving populations are isolated from one another. Further research and the implementation of conservation strategies are required in order to ensure this species' survival.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Historically, this species occurred throughout the Tennessee River drainage as far south as Mussel Shoals, including sections of the Elk, Flint, Paint Rock, Clinch, Powell, North Fork Holston, and Tennessee Rivers (USFWS 1984).

Its current distribution is scattered over five rivers: the North Fork of the Holston in Virginia, the Clinch (from the Virginia-Tennessee border upstream to Nash Ford), the Powell (from the Virginia-Tennessee border upstream to Lee County, Tennessee), the Elk River in Tennessee (although it has not been seen here since 1980) and the Paint Rock River in Alabama, where it is uncommon (Mirarchi et al. 2004, USFWS 1984).

Its current distribution is scattered over five rivers (assessed as five locations) and the limited range of this species is becoming even more restricted (two of the rivers may no longer be viable) due to changes in water quality. The extent of occurrence is estimated as no more than 5,000 km2. Declines have been significant (80% of range) and existing populations are isolated from one another.
Countries occurrence:
United States (Alabama, Tennessee, Virginia)
Additional data:
Estimated area of occupancy (AOO) - km2:500-2000
Number of Locations:5
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:A 1980 survey for Virginia Game and Inland Fisheries put the number of sites in Virginia at 30 (Neves 1991), about half of which are considered historical or extirpated (the species is likely to be still extant in Virginia in Powell, Upper Clinch, North and South Fork Holston); populations of the mussel are disjunct throughout its range. No comprehensive surveys have been conducted throughout its range, however, it remains as a relict population in many stretches of the Clinch, including Copper Creek (Fraley and Ahlstedt 2000, Jones et al. 2001) and Powell Rivers in Tennessee and Virginia, and in the Paint Rock River in northern Alabama, particularly the unimpounded sections (Parmalee and Bogan 1998). Jones and Neves (2007) summarize the distribution in the upper North Fork Holston River (Smyth and Bland Cos., Virginia) as river km 136.2 to 154.3. Since 1970, the species has been taken from several tributaries of the Tennessee River including the North Fork Holston River, Clinch River, Powell River, Elk River, and Paint Rock River (USFWS 1984, 2006). A 210 km survey of the Elk River from the Alabama border through Tennessee in 1980 found this species at a few sites in Lincoln/Moore Cos., Tennessee (Ahlstedt 1983). In Tennessee, it once occurred in the Clinch River, from Hancock Co. downstream to Roane Co., and in the Powell River, from Hancock Co. downstream to Campbell Co.. However, it is now restricted to unimpounded stretches of these rivers in Claiborne and Hancock Cos. (Parmalee and Bogan 1998). In Alabama, it was once distributed across the northern part of the state, but now is only extant in the Paint Rock River (Mirarchi et al. 2004).

The species is now believed to be extirpated in the Tennessee, Holston, and Elk Rivers in Tennessee (Parmalee and Bogan 1998). It is also believed to be extirpated in the Flint River (USFWS 1984) and Tennessee River proper in Alabama (Mirarchi et al. 2004). The species was once common throughout much of the Tennessee River, but was never recorded from the Duck or Cumberland Rivers (USFWS 1984). This species has lost at least 80% of its known range over the last 25 to 50 years (A. Bogan pers. comm. 2010).

A few sites in Virginia have the best viability, as does the population in the Clinch River on the Tennessee side (considered the most viable extant population). Sites with recent recruitment exists in the North Fork Holston River above Saltville, Virginia; Clinch River in Tennessee to Russell Co., Virginia; Powell River from Norris Reservoir upstrream to Lee Co., Virginia/ Elk River in Lincoln Co., Tennessee; Paint Rock River in Jackson Co., Alabama; and Copper Creek in Scott Co., Virginia (USFWS 1984).

Jones and Neves (2007) recorded a die-off in the North Fork Holston River in Virginia beginning in 1999. Hanlon et al. (2009) showed similar declines in Copper Creek, Virginia, Eckert et al. (2010) on Cleveland Island on the Clinch River, and Eckert & Pinder (2008) in Clinchport on the Clinch River.

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is found in shoals and riffles of small to medium sized rivers in clear streams with moderate to fast current (Bogan and Parmalee 1983). It is typically well burrowed in sand and cobble substrates. It does not appear tolerant of deeper water or reservoirs (USFWS 1984).

This species is a short-term brooder. Ortmann (1921) reported gravid females from mid-May to mid-July. However, he stated that “none happened to have glochidia.” Presumably they were gravid with eggs or developing embryos. Females gravid with mature glochidia have been reported in July and August (Jones and Neves 2007) and glochidia have been reported in stream drift in the North Fork Holston River, southwestern Virginia, during the same period (Kitchel 1985) (Williams et al. 2008).

Cyprinella galactura (Whitetail Shiner, Cyprinidae) was found to serve as a glochidial host of the species in laboratory trials (Neves 1991). Fishes found to be marginal hosts in laboratory trials include Luxilus chrysocephalus (Striped Shiner) and Luxilus coccogenis (Warpaint Shiner, Cyprinidae); and Etheostoma rufilineatum (Redline Darter, Percidae; Jones and Neves 2001). Fishes in the North Fork Holston River for which observations of natural infestation with this species' glochidia have been reported include Luxilus cornutus (Common Shiner) and Notropis telescopus (Telescope Shiner, Cyprinidae; Kitchel 1985, Williams et al. 2008).
Congregatory:Congregatory (and dispersive)

Use and Trade [top]

Use and Trade: This species is not utilised.

Threats [top]

Major Threat(s): This species is sensitive to changing water quality and physical disruption. It is therefore threatened by habitat alteration and pollution from strip mine runoff and coal washing. Intensive industrial and agricultural development of the Tennessee Valley since the early 1900s has had a significant impact upon the mussel fauna inhabiting the Tennessee River basin. Dam construction in the upper Tennessee River system may have been the most significant factor. Dams were constructed for hydroelectric power, flood control, and navigation, as well as recreation. Siltation has also impacted the species (from strip mining, coal mining, road construction, forestry and agricultural operations). Pollution is also a factor, from heavy metals, industrial effluent, chemical spills, agricultural waste, fertilizers, pesticides, and human waste (USFWS 1984). Populations in the North Fork of Holston and Clinch rivers were reduced by toxic discharges and spills prior to 1972. Some sizable populations in the Elk River were destroyed by impoundment of Tims Ford Reservoir. The invasion of the Asian clam, and the possible invasion of the zebra mussel, also threaten remaining populations.

Conservation Actions [top]

Conservation Actions: This species was listed as federally endangered in 1976 in the U.S., and a recovery plan was created (USFWS 1984) and an experimental reintroduced population established (USFWS 2001, 2006). Williams et al. (2010) lists this species as Endangered according to the AFS assessment. The species has also been assigned a NatureServe Global Heritage Status Rank of G1 - Critically Imperilled, as well as State/Province Status Ranks of S1 - Critically Imperilled for the states of Alabama, Tennessee and Virginia (NatureServe 2009).

Pendleton Island in the Clinch River is a TNC preserve. Nonessessential Experimental Populations (NEPs) have been established in the Tennessee River below Wilson Dam, Colbert and Lauderdale Cos., Alabama, extending13.4 km and including the lower 8 km of all tributaries that enter the Wilson Dam tailwaters (USFWS 2001). Nonessential Experimental Populations (NEPs) have been proposed for reintroduction into the free-flowing reach of the French Broad River below Douglas Dam (Knox and Sevier Cos., Tennessee) to its confluence with the Holston River, Knox Co., Tennessee, and in the free-flowing reach of the Holston River below Cherokee Dam to its confluence with the French Broad River (Knox, Grainger, and Jefferson Cos., Tennessee), where this species currently does not exist (USFWS 2006).

Further research regarding this species' taxonomy, ecology, population status and threats impacting this species is recommended. Conservation measures are needed in order to ensure this species' long-term survival, including site and species protection (with particular emphasis on the enforcement of protection), and a continuation of current management and population augmentation methods.

Citation: Cummings, K. & Cordeiro, J. 2012. Fusconaia cor. The IUCN Red List of Threatened Species 2012: e.T8778A3146798. . Downloaded on 23 May 2018.
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