Fusconaia burkei - (Walker, 1922)
Tapered Pigtoe
Other English Common Names: tapered pigtoe
Taxonomic Status: Accepted
Related ITIS Name(s): Quincuncina burkei Walker, 1922 (TSN 80355)
Unique Identifier: ELEMENT_GLOBAL.2.116875
Element Code: IMBIV40010
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Fusconaia
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Quincuncina burkei
Taxonomic Comments: In a phylogenetic analysis based on genetic sequence data, Quincuncina burkei was determined to be sister to Fusconaia escambia (Serb et al., 2003). Based on similarity of soft anatomy and results of genetic analyses, burkei is recognized as belonging to the genus Fusconaia (Williams et al., 2008).
Conservation Status
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NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 14Jan2014
Global Status Last Changed: 31Aug2000
Rounded Global Status: G2 - Imperiled
Reasons: This regional endemic has always been limited to a single watershed, the Choctawhatchee River system. Although recently found at eight sites in the Pea River system, it appears to be extirpated from multiple, historical sites and is confined primarily to main channel habitats. Deteriorating water and habitat quality throughout the Choctawhatchee drainage is a probable threat.
Nation: United States
National Status: N2N3 (31Aug2000)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (S2), Florida (S2)

Other Statuses

U.S. Endangered Species Act (USESA): LT: Listed threatened (10Oct2012)
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: NT - Near threatened
American Fisheries Society Status: Threatened (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: 5000-200,000 square km (about 2000-80,000 square miles)
Range Extent Comments: The tapered pigtoe is endemic to the Choctawhatchee River drainage in Alabama and Florida (Clench and Turner, 1956; Williams and Butler, 1994; USFWS, 2003; Blalock-Herod et al., 2005). Additionally, a relic shell was found recently in Big Creek, Pike County, Alabama (Blalock-Herod et al., 2005). Specific Florida records include Horseshoe Lake (an oxbow lake with flowing connection to the main channel of the Choctawhatchee River), Washington County; Limestone Creek, Walton County; East Pitman Creek, Holmes County; Choctawhatchee River, Washington, Walton, and Holmes Counties; Holmes Creek, Washington and Holmes counties; and Tenmile Creek, Holmes County. In Alabama, the historical distribution of the tapered pigtoe included Flat and Hurricane creeks, Geneva County; Pea River, Barbour, Coffee and Dale counties; Choctawhatchee River, Dale County; Little Choctawhatchee River, Dale and Houston Counties; East Fork Choctawhatchee River, Dale County; Bear and Panther creeks; Houston County; and West Fork Choctawhatchee River, Barbour County (Blalock-Herod et al., 2005).

Area of Occupancy: 126-2,500 4-km2 grid cells
Area of Occupancy Comments: Linear occupancy is unknown.

Number of Occurrences: 1 - 20
Number of Occurrences Comments: The following locations known from historical museum records continue to support tapered pigtoe populations: Limestone Creek, Walton County, Florida; East Pittman Creek, Holmes County, Florida; Choctawhatchee River, Washington, Walton, and Holmes counties, Florida; Holmes Creek, Washington and Holmes counties, Florida; and Flat Creek, Geneva County, Alabama (fide Blalock-Herod et al., 2005). During recent status surveys, the tapered pigtoe was found live and as shell material at 33 of 54 historical sites. Populations were inactive at 15 historical sites, and status was undetermined at 6 sites (fide Blalock-Herod et al., 2005). In Alabama, the species is extant at 9 locations in tributaries of the Choctawhatchee drainage, including headwaters of the Pea River (Mirarchi et al., 2004). Blalock-Herod et al. (2005) list the species historically from 40 localities in the Choctawhatchee River drainage in Alabama and Florida (extant in 7) and cite 26 new locations in the drainage in isolated spots in the headwaters, the Flat Creek watershed, and the main channel and some tributaries in Florida. Pilarczyk et al. (2006) recorded recent collections (in 2004) of this species at 4 of 24 sites in Alabama. In Alabama, it is found in the Choctawhatchee River drainage, including the Pea River system in isolated tributaries and headwaters (Williams et al., 2008). Gangloff and Hartfield (2009) found it in 2 Pea River sites in Alabama.

Population Size: 2500 - 100,000 individuals
Population Size Comments: In 1987 at the the best known site, 37 specimens were found in one hour's time. However, its numbers are generally smaller, at least in Florida's recent records. During recent status surveys, the species was found live and as shell material at 33 of 54 historical sites with an average of 7 individuals per site. Populations were inactive at 15 historical sites, and status was undetermined at 6 sites. Four populations were represented by 10 - 20 individuals (fide Blalock-Herod et al., 2005). Pilarczyk et al. (2006) recorded recent collections (in 2004) of this species following surveys of 24 sites in Alabama in several stream systems including West Fork Choctawhatchee River (5 live), Eightmile Creek in Florida (29 live), Pea Creek (5 live), and Big Creek (1 live).

Number of Occurrences with Good Viability/Integrity: Very few to few (1-12)
Viability/Integrity Comments: Blalock-Herod et al. (2005) list this species historically from 40 localities in the Choctawhatchee River drainage in Alabama and Florida (extant in 7) and 26 new locations in the drainage in isolated spots in the headwaters, the Flat Creek watershed, and the main channel and some tributaries in Florida. Pilarczyk et al. (2006) recorded recent collections (in 2004) of this species following surveys of 24 sites in four stream systems in Alabama including West Fork Choctawhatchee River, Eightmile Creek (in Florida), Pea Creek, and Big Creek compared to Flat Creek, Eightmile Creek (just over the border in Florida), Pea River, Pea Creek, Big Creek, West Fork Choctawhatchee River, and Judy Creek in surveys of the same sites in the 1990s.

Overall Threat Impact: High
Overall Threat Impact Comments: Habitat loss or degradation is the primary threat to this species. Its stream and river habitats are vulnerable to habitat modification, sedimentation, and water quality degradation from a number of activities. Highway and reservoir construction, improper logging practices, agricultural runoff, housing developments, pipeline crossings, and livestock grazing often result in physical disturbance of stream substrates or the riparian zone, and/or changes in water quality, temperature, or flow. Sedimentation can cause direct mortality of mussels by deposition and suffocation (Ellis, 1936; Brim Box and Mossa, 1999) and can eliminate or reduce the recruitment of juvenile mussels (Negus, 1966; Brim Box and Mossa, 1999). Suspended sediment can also interfere with feeding activity of mussels (Dennis, 1984). Many of the confirmed extant populations of this species are in the vicinity of highway and unpaved road crossings due to ease of access for surveyors. Highway and bridge construction and widening could affect such populations unless appropriate precautions are implemented during construction to reduce erosion and sedimentation and to maintain water quality standards. The construction of reservoirs and the associated habitat changes (e.g., changes of sediments, flow, water temperature, dissolved oxygen) can directly impact mussel populations (Neves et al., 1997). Nutrients, usually phosphorus and nitrogen, may emanate from agricultural fields, residential lawns, livestock feedlots, poultry houses, and leaking septic tanks in levels that result in eutrophication and reduced oxygen levels in small streams. Other factors include (1) over-utilization for commercial, recreational, scientific, or educational purposes (note: species is not commercially valuable nor are the streams and rivers it inhabits subject to harvesting activities for commercial mussel species); (2) disease or predation (poorly known but may contribute to the further decline of this species due to its restricted distribution and low numbers associated with extant populations); (3) the inadequacy of existing regulatory mechanisms (note: less success in dealing with non-point source pollution impacts, particularly sediments, to small stream drainages); (4) catastrophic events (populations are generally small and geographically isolated; (5) host fish loss or decline (host not known); (6) populations below effective population size to maintain long-term viability (some populations below required population size to maintain long-term genetic viability); and (7) invasive species (Asiatic clam, zebra mussel, black carp) (see USFWS, 2003).

Short-term Trend: Decline of 10-30%
Short-term Trend Comments: This species si apparently declining, like most regional endemics. It is difficult to find in most streams, even where biodiversity, habitat, and benthic quality are generally good. Its existence in some lower mainstem sites and localized creek situations may be doubtful due to general habitat degradation, primarily from siltation. The tapered pigtoe has been extirpated from approximately 28% of its historic range. Recruitment status is unknown but may be occurring at low levels within existing populations (USFWS, 2003).

Long-term Trend: Decline of 30-50%
Long-term Trend Comments: In Alabama, populations of the tapered pigtoe appear to be extirpated from Hurricane Creek, Geneva County; Bear and Panther creeks, Houston County; Little Choctawhatchee River, Houston and Dale Counties; Pea River, Coffee and Dale counties; Choctawhatchee River and East Fork Choctawhatchee River, Dale county, and probably Big Creek, Pike County (USFWS, 2003).

Intrinsic Vulnerability: Moderately vulnerable
Intrinsic Vulnerability Comments: Freshwater mussels are inherently vulnerable to threats from siltation, pollution, eutrophication, channelization, impoundment, collection, drought and water withdrawal, competiton from invasive non-native mussels, and changes to larval host fish populations. Fragmentation of populations may limit this species' dispersal capability.

Environmental Specificity: Unknown

Other NatureServe Conservation Status Information

Inventory Needs: Although there have been relatively recent surveys (Blalock et al. 1998, Williams et al., in preparation), additional surveys are always useful. Inventory potential habitats for future reintroduction of cultured stock/transplants.

Protection Needs: Maintain high water and benthic habitat (substrate) qualities, as well as adequate flow regimes, throughout the Choctawhatchee River system. This may be partially accomplished via establishment of buffers and streamside management zones for all agricultural, silvicultural, mining, and developmental activities; protection of floodplain forests and adjoining upland habitat is paramount. Best management practices to follow include employing forestry practices that cause minimal soil erosion; preventing access of livestock to natural surface waters and drains; situating roads at least 0.25 mile (0.4 km) from heads of all tributaries, even more on steep slopes; using silt fencing and vegetation to control runoff and siltation at all stream crossings, especially during construction and maintenance; using and maintaining sewer systems rather than septic tanks and stream-dumping for management of wastewater; and avoiding use of agricultural pesticides on porous soils near streams. Prevent damming, dredging, and pollution throughout drainages, but especially near recorded sites. Remove existing dams, but with great care to limit downstream sedimentation. Limit withdrawal of surface and subterranean waters as necessary to maintain normal stream flows, especially during drought. Prevent or limit establishment of invasive species (including zebra mussel, Dreissena polymorpha) to the extent possible. Where appropriate, protect populations through acquisitions and easements over streamside lands by working with government agencies and conservation organizations. Also consider culture/reintroduction projects if populations decline further. See also U.S. Fish and Wildlife Service, 2003).

Distribution
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Global Range: (5000-200,000 square km (about 2000-80,000 square miles)) The tapered pigtoe is endemic to the Choctawhatchee River drainage in Alabama and Florida (Clench and Turner, 1956; Williams and Butler, 1994; USFWS, 2003; Blalock-Herod et al., 2005). Additionally, a relic shell was found recently in Big Creek, Pike County, Alabama (Blalock-Herod et al., 2005). Specific Florida records include Horseshoe Lake (an oxbow lake with flowing connection to the main channel of the Choctawhatchee River), Washington County; Limestone Creek, Walton County; East Pitman Creek, Holmes County; Choctawhatchee River, Washington, Walton, and Holmes Counties; Holmes Creek, Washington and Holmes counties; and Tenmile Creek, Holmes County. In Alabama, the historical distribution of the tapered pigtoe included Flat and Hurricane creeks, Geneva County; Pea River, Barbour, Coffee and Dale counties; Choctawhatchee River, Dale County; Little Choctawhatchee River, Dale and Houston Counties; East Fork Choctawhatchee River, Dale County; Bear and Panther creeks; Houston County; and West Fork Choctawhatchee River, Barbour County (Blalock-Herod et al., 2005).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States AL, FL

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
AL Barbour (01005), Coffee (01031)*, Dale (01045), Geneva (01061)*, Henry (01067), Pike (01109)
FL Holmes (12059), Walton (12131), Washington (12133)*
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Upper Choctawhatchee (03140201)+, Pea (03140202)+, Lower Choctawhatchee (03140203)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
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Basic Description: A small, relatively thick shelled, subtriangular, sculptured freshwater mussel.
General Description: The tapered pigtoe is a small mussel that attains a maximum length of 60 mm. The shell is inflated and subelliptical in outline. The anterior margin is broadly rounded and the posterior margin is narrowly pointed. The posterior ridge is well defined with radial ridges on the posterior slope. Chevron-shaped ridges cover much of the disk. Shell sculpture may be indistinct in some specimens. The periostracum is brown or greenish-yellow in young specimens, but becomes dark brown to black in adults. Pseudocardinal teeth are well-developed, divergent, and double in both valves. There are two lateral teeth in left valve and usually one in right valve. The interdentum is very narrow. Shell nacre varies from light purple to bluish-white (Garner et al., in review; Clench and Turner, 1956; Deyrup and Franz, 1994).
Diagnostic Characteristics: Small, rarely medium-sized, unique sculpture consisting of rows of radial plications down the posterior slope and disc, unrayed, brown periostracum, heavier shelled than superficially similar and sometimes sympatric Medionidus penicillatus (I. Lea, 1857).
Reproduction Comments: Possibly this species is tachytictic (short-term brooder), as are members of the somewhat closely related (possibly congeneric) genus Fusconaia. White et al. (2008) tested host suitability on 10 potential fish species and confirmed transformation only on Cyprinella venusta (blacktail shiner). Conglutinates were pink colored and cylindrical in shape, tapering sharply on both ends.
Habitat Type: Freshwater
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: Adults are essentially sessile. About the only voluntary movement they make is to burrow deeper into the substrate although some passive movement downstream may occur during high flows. Dispersal occurs while the glochidia are encysted on their host (probably a fish).
Riverine Habitat(s): BIG RIVER, CREEK, Low gradient, MEDIUM RIVER, Moderate gradient, Riffle
Special Habitat Factors: Benthic
Habitat Comments: The tapered pigtoe is found in medium-sized creeks to large rivers in stable sand or sand and gravel substrata, occasionally occurring in silty sand in slow to moderate current (Williams and Butler, 1994).
Adult Food Habits: Detritivore
Immature Food Habits: Parasitic
Food Comments: Presumably fine particulate organic matter, primarily detritus, and/or zooplankton, and/or phytoplankton (Fuller, 1974). Larvae (glochidia) of freshwater mussels generally are parasitic on fish and there may be a specificity among some species.
Length: 6 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: This species was listed as a federal candidate for protection in the U.S. in 2004 (USFWS, 2003). Conservation activities have been limited to working with landowners in west Alabama and south Florida to limit the effects of agricultural practices on populations. This species has probably been negatively affected greatest by poor land use practices resulting in habitat destruction and leading to decline and imperilment.
Biological Research Needs: Determine life history, reproductive biology, fecundity, viability of extant populations, microhabitat requirements, sensitivity to silt, excessive nutrients, and pollutants; develop propagation techniques; identify host fish, its requirements, and population status; determine competitive interaction with Corbicula fluminea.
Population/Occurrence Delineation
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Group Name: Freshwater Mussels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached and/or nacre still glossy and iridescent without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information.
Mapping Guidance: Based on the separation distances outlined herein, for freshwater mussels in STANDING WATER (or backwater areas of flowing water such as oxbows and sloughs), all standing water bodies with either (1) greater than 2 km linear distance of unsuitable habitat between (i.e. lotic connections), or (2) more than 10 km of apparently unoccupied though suitable habitat (including lentic shoreline, linear distance across water bodies, and lentic water bodies with proper lotic connections), are considered separate element occurrences. Only the largest standing water bodies (with 20 km linear shoreline or greater) may have greater than one element occurrence within each. Multiple collection or observation locations in one lake, for example, would only constitute multiple occurrences in the largest lakes, and only then if there was some likelihood that unsurveyed areas between collections did not contain the element.

For freshwater mussels in FLOWING WATER conditions, occurrences are separated by a distance of more than 2 stream km of unsuitable habitat, or a distance of more than 10 stream km of apparently unoccupied though suitable habitat. Standing water between occurrences is considered suitable habitat when calculating separation distance for flowing water mussel species unless dispersal barriers (see Separation Barriers) are in place.

Several mussel species in North America occur in both standing and flowing water (see Specs Notes). Calculation of separation distance and determination of separation barriers for these taxa should take into account the environment in which the element was collected. Juvenile mussels do not follow this pattern and juveniles are typically missed by most standard sampling methods (Hastie and Cosgrove, 2002; Neves and Widlak, 1987), therefore juvenile movement is not considered when calculating separation distance.

Separation Barriers: Separation barriers within standing water bodies are based solely on separation distance (see Separation Distance-suitable, below). Separation barriers between standing water bodies and within flowing water systems include lack of lotic connections, natural barriers such as upland habitat, absence of appropriate species specific fish hosts, water depth greater than 10 meters (Cvancara, 1972; Moyle and Bacon, 1969) or anthropogenic barriers to water flow such as dams or other impoundments and high waterfalls.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: None
Separation Justification: Adult freshwater mussels are largely sedentary spending their entire lives very near to the place where they first successfully settled (Coker et al., 1921; Watters, 1992). Strayer (1999) demonstrated in field trials that mussels in streams occur chiefly in flow refuges, or relatively stable areas that displayed little movement of particles during flood events. Flow refuges conceivably allow relatively immobile mussels to remain in the same general location throughout their entire lives. Movement occurs with the impetus of some stimulus (nearby water disturbance, physical removal from the water such as during collection, exposure conditions during low water, seasonal temperature change or associated diurnal cycles) and during spawning. Movement is confined to either vertical movement burrowing deeper into sediments though rarely completely beneath the surface, or horizontal movement in a distinct path often away from the area of stimulus. Vertical movement is generally seasonal with rapid descent into the sediment in autumn and gradual reappearance at the surface during spring (Amyot and Downing, 1991; 1997). Horizontal movement is generally on the order of a few meters at most and is associated with day length and during times of spawning (Amyot and Downing, 1997). Such locomotion plays little, if any, part in the distribution of freshwater mussels as these limited movements are not dispersal mechanisms. Dispersal patterns are largely speculative but have been attributed to stream size and surface geology (Strayer, 1983; Strayer and Ralley, 1993; van der Schalie, 1938), utilization of flow refuges during flood stages (Strayer, 1999), and patterns of host fish distribution during spawning periods (Haag and Warren, 1998; Watters, 1992). Lee and DeAngelis (1997) modeled the dispersal of freshwater into unoccupied habitats as a traveling wave front with a velocity ranging from 0.87 to 2.47 km/year (depending on mussel life span) with increase in glochidial attachment rate to fish having no effect on wave velocity.

Nearly all mussels require a host or hosts during the parasitic larval portion of their life cycle. Hosts are usually fish, but a few exceptional species utilize amphibians as hosts (Van Snik Gray et al., 2002; Howard, 1915) or may metamorphose without a host (Allen, 1924; Barfield et al., 1998; Lefevre and Curtis, 1911; 1912). Haag and Warren (1998) found that densities of host generalist mussels (using a variety of hosts from many different families) and displaying host specialists (using a small number of hosts usually in the same family but mussel females have behavioral modifications to attract hosts to the gravid female) were independent of the densities of their hosts. Densities of non-displaying host specialist mussels (using a small number of hosts usually in the same family but without host-attracting behavior) were correlated positively with densities of their hosts. Upstream dispersal of host fish for non-displaying host specialist mussels could, theoretically, transport mussel larvae (glochidia) over long distances through unsuitable habitat, but it is unlikely that this occurs very often. D. Strayer (personal communication) suggested a distance of at least 10 km, but a greater distance between occurrences may be necessary to constitute genetic separation of populations. As such, separation distance is based on a set, though arbitrary, distance between two known points of occurrence.

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Contact Jay Cordeiro (jay_cordeiro@natureserve.org) for a complete list of freshwater mussel taxa sorted by flow regime.
Population/Occurrence Viability
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Justification: Use the Generic Element Occurrence Rank Specifications (2008).
Key for Ranking Species Element Occurrences Using the Generic Approach (2008).
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 14Jan2014
NatureServe Conservation Status Factors Author: Jackson, D. R. (2014); Cordeiro, J. (2011); Butler, R.S. (1992); Brim Box, J. (2000)
Management Information Edition Date: 08Mar2005
Management Information Edition Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 23Dec2011
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Blalock, H.N., J.J. Herod, and J.D. Williams. 1998. Freshwater mussels (Unionacea: Bivalvia) of the Pea River Watershed of Alabama and Florida. Final Report for the U.S. Fish and Wildlife Service, Jacksonville, Florida. 61 pp.

  • Blalock-Herod, H. N., J. J. Herod, J. D. Williams, B. N. Wilson, and S. W. McGregor. 2005. A historical and current perspective of the freshwater mussel fauna (Bivalvia: Unionidae) from the Choctawhatchee River drainage in Alabama and Florida. Bulletin of the Alabama Museum of Natural History 24:1-26.

  • Blalock-Herod, H.N., J.J. Herod, J.D. Williams, B.N. Wilson, and S.W. McGregor. 2005. A historical and current perspective of the freshwater mussel fauna (Bivalvia: Unionidae) from the Choctawhatchee River drainage in Alabama and Florida. Bulletin of the Alabama Museum of Natural History, 24: 1-26.

  • Brim Box, J. and J. Mossa. 1999. Sediment, land use, and freshwater mussels: prospects and problems. Journal of the North American Benthological Society, 18(1): 99-117.

  • Clench, W.J. and R.D. Turner. 1956. Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwanee River. Bulletin of the Florida State Museum Biological Sciences, 1(3): 97-239.

  • Dennis, S.D. 1984. Distributional analysis of the freshwater mussel fauna of the Tennessee River system, with special reference to possible limiting effects of siltation. Ph.D. Thesis. Virginia Polytechnic Institute and State University, Blacksburg, Virginia. 247 pp.

  • Deyrup, M., and R. Franz. 1994. Rare and Endangered Biota of Florida, Volume IV: Invertebrates. University Press of Florida, Gainesville. 798 pp.

  • Ellis, M.M. 1936. Erosion silt as a factor in aquatic environments. Ecology, 17: 29-42.

  • Fuller, S.L.H. 1974. Chapter 8: Clams and mussels (Mollusca: Bivalvia). Pages 215-273 in: C.W. Hart, Jr. and S.L.H. Fuller (eds.) Pollution Ecology of Freshwater Invertebrates. Academic Press: New York. 389 pp.

  • Gangloff, M.M. and P.W. Hartfield. 2009. Seven populations of the southern kidneyshell (Ptychobranchus jonesi) discovered in the choctawhatachee River basin, Alabama. Southeastern Naturalist 8(2):245-254.

  • Garner, J.T., H.N. Blalock-Herod, A.E. Bogan, R.S. Butler, W.R. Haag, P.D. Hartfield, J.J. Herod, P.D. Johnson, S.W. McGregor, and J.D. Williams. In review. Freshwater mussels and snails. Alabama Non-Game Symposium. University of Auburn Press.

  • Heard, W.H. 1979. Identification manual of the fresh water clams of Florida. State of Florida, Department of Environmental Regulation, Technical Series, 4(2): 1-82.

  • Howard, A.D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.

  • Lefevre, G. and W.T. Curtis. 1912. Studies on the reproduction and artificial propogation of fresh-water mussels. Bulletin of the Bureau of Fisheries 30:102-201.

  • Mirarchi, R.E., J.T. Garner, M.F. Mettee, and P.E. O'Neil. 2004b. Alabama wildlife. Volume 2. Imperiled aquatic mollusks and fishes. University of Alabama Press, Tuscaloosa, Alabama. xii + 255 pp.

  • Moyle, P. and J. Bacon. 1969. Distribution and abundance of molluscs in a fresh water environment. Journal of the Minnesota Academy of Science 35(2/3):82-85.

  • Negus, C.L. 1966. A quantitative study of growth and production of unionid mussels in the River Thames at Reading. Journal of Animal Ecology, 35: 513-532.

  • Neves, R.J., A.E. Bogan, J.D. Williams, S.A. Ahlstedt, and P.W. Hartfield. 1997. Status of aquatic mollusks in the southeastern United States: a downward spiral of diversity. Pages 43-85 in G.W. Benz and D.E. Collins (eds.) Aquatic Fauna in Peril: the Southeastern Perspective. Special Publication 1, Southeast Aquatic Research Institute, Chattanooga, Tennessee.

  • Serb, J.M., J.E. Buhan, and C. Lydeard. 2003. Molecular systematics of the North American freshwater bivalve genus Quadrula (Unionidae: Ambleminae) based on mitochondrial ND1 sequences. Molecular Phylogenetics and Evolution, 28: 1-11.

  • Strayer, D. 1983. The effects of surface geology and stream size on freshwater mussel (Bivalvia, Unionidae) distribution in southeastern Michigan, U.S.A. Freshwater Biology 13:253-264.

  • Strayer, D.L. 1999a. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.

  • Strayer, D.L. and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of Alasmidonta. Journal of the North American Benthological Society 12(3):247-258.

  • Turgeon, D.D., J.F. Quinn, Jr., A.E. Bogan, E.V. Coan, F.G. Hochberg, W.G. Lyons, P.M. Mikkelsen, R.J. Neves, C.F.E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F.G. Thompson, M. Vecchione, and J.D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland: 526 pp.

  • U.S. Fish and Wildlife Service (USFWS). 2003. Candidate and listing priority assignment form: Fusconaia rotulata, Ptychobranchus jonesi, Fusconaia escambia, Lampsilis australis, Pleurobema strodeanum, Villosa choctawensis, Quincuncina burkei. U.S. Fish and Wildlife Service, Panama City Field Office, Panama. 20 pp.

  • U.S. Fish and Wildlife Service. 2011i. Endangered and threatened wildlife and plants; endangered status for the Alabama pearlshell, round ebonyshell, southern sandshell, southern kidneyshell, and choctaw bean, and threatened status for the tapered pigtoe, narrow pigtoe, and fuzzy pigtoe; with critical habitat. Federal Register 76(192):61482-61529.

  • U.S. Fish and Wildlife Service. 2012f. Endangered and threatened wildlife and plants; endangered species status for the Alabama pearlshell, round ebonyshell, southern kidneyshell, and choctaw bean, and threatened species status for the tapered pigtoe, narrow pigtoe, southern sandshell, and fuzzy pigtoe; and designation of critical habitat; final rule. Federal Register 77(196):61664-61719.

  • Van der Schalie, H. 1938a. The naiad fauna of the Huron River in southeastern Michigan. Miscellaneous Publication of the Museum of Zoology, University of Michigan 40:7-78.

  • Watters, G.T. 1992a. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.

  • White, M.P., H.N. Blalock-Herod, and P.M. Stewart. 2008. Life history and fish host identification for Fusconaia burkei and Pleurobema strodeanum (Bivalvia: Unionidae). American Malacological Bulletin, 24(1/2): 121-125.

  • Williams, J. D., A. E. Bogan, and J. T Garner. 2008. Freshwater mussels of Alabama & the Mobile Basin in Georgia, Mississippi, & Tennessee. University of Alabama Press, Tuscaloosa, Alabama. 908 pages.

  • Williams, J. D., A. E. Bogan, and J. T. Garner. 2008. Freshwater Mussels of Alabama and the Mobile Basin in Georgia, Mississippi and Tennessee. University of Alabama Press, Tuscaloosa, Alabama. 908 pp.

  • Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson.  2014.  Freshwater Mussels of Florida.  University of Alabama Press, Tuscaloosa.  498 pp.

  • Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson.  2014a.  Freshwater Mussels of Florida.  University of Alabama Press, Tuscaloosa, Alabama. 498 pp.

  • Williams, J.D. and R.S. Butler. 1994. Class Bivalvia, Order Unionoida, freshwater bivalves. Pages 53-128, 740-742 in M. Deyrup and R. Frantz (eds.) Rare and Endangered Biota of Florida. Volume 4. Invertebrates. University Press of Florida, Gainesville, Florida. 798 pp.

  • Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993b. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9): 6-22.

  • Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993b. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9):6-22.

References for Watershed Distribution Map
  • Pilarczyk, M.M., P.M. Stewart, D.N. Shelton, H.N. Blalock-Herod, and J.D. Williams. 2006. Current and Recent historical freshwater mussel assemblages in the Gulf Coastal Plains. Southeastern Naturalist, 5(2): 205-226.

  • Williams, J.D., A.E. Bogan, and J.T. Garner. 2008. Freshwater Mussels of Alabama & the Mobile Basin in Georgia, Mississippi & Tennessee. University of Alabama Press: Tuscaloosa, Alabama. 908 pp.

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