Alasmidonta atropurpurea - (Rafinesque, 1831)
Cumberland Elktoe
Taxonomic Status: Accepted
Related ITIS Name(s): Alasmidonta atropurpurea (Rafinesque, 1831) (TSN 79928)
Unique Identifier: ELEMENT_GLOBAL.2.119501
Element Code: IMBIV02020
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
 
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Alasmidonta
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: Alasmidonta atropurpurea
Taxonomic Comments: This species was ignored until Frierson (1927) resurrected it as a subspecies of Alasmidonta marginata. Clarke (1981) demonstrated its validity as a distinct species. It previously has been confused with Alasmidonta raveneliana due to Rafinesque's omission of reference to the corrugations on the posterior slope (his specimens apparently were encrusted with black deposits which obscurred this character). see Bogan et al. (2009).
Conservation Status
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NatureServe Status

Global Status: G1G2
Global Status Last Reviewed: 17Nov2011
Global Status Last Changed: 28Oct2003
Rounded Global Status: G1 - Critically Imperiled
Reasons: Historically, this mussel had a rather limited distribution. This distribution has been further restricted by pollution from coal mine run-off and other sources, and through inundation caused by reservoirs. The continuing development of coal mines, particularly strip mines, poses the primary threat to the limited habitat. This species has a limited range in one river system in the Cumberland Plateau in Tennessee and Kentucky that is fragmented into three disjunct sections of the former range and has experienced decline (50-70%) over the years to about a dozen occurrences, only two or three of which are considered to have decent viability. Area of occupancy within the narrow range is discontinuous and very small and continued decline has been observed recently.
Nation: United States
National Status: N1N2 (15Dec1998)

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 Kentucky (S1), Tennessee (S1S2)

Other Statuses

U.S. Endangered Species Act (USESA): LE: Listed endangered (10Jan1997)
U.S. Fish & Wildlife Service Lead Region: R4 - Southeast
IUCN Red List Category: EN - Endangered
American Fisheries Society Status: Endangered (01Jan1993)

NatureServe Global Conservation Status Factors

Range Extent: 1000-5000 square km (about 400-2000 square miles)
Range Extent Comments: Historically, this species was known only from the Cumberland Plateau province of the upper Cumberland River basin of Kentucky and Tennessee (Parmalee and Bogan, 1998; Cicerello and Schuster, 2003). All verified sites of occurrence are in the Cumberland Plateau Physiographic Province, giving it one of the most restricted ranges of any Cumberlandian species. The few records available indicate that it inhabited the Cumberland River and only tributaries flowing from the south upstream from the hypothesized original location of Cumberland Falls near Burnside, Pulaski County, Kentucky. A single record exists for the Collins River, in the upper Caney Fork River system above Great Falls. It presently (post-1985 records) persists in eight tributaries to the Upper Cumberland River in Kentucky and Tennessee (USFWS, 1998). It is extirpated from the mainstem of the Cumberland River, Laurel River and its tributary, Lynn Camp Creek in Kentucky. Formerly from 19 localities and currently persisting in 12 Cumberland River tributaries (USFWS, 2003; 2004).

Area of Occupancy: 126-2,500 4-km2 grid cells
Area of Occupancy Comments: Recently, critical habitat was designated for Rock Creek (17 river km occupied, 0 river km unoccupied habitat) in Kentucky, Big South Fork (43 river km occupied, 0 river km unoccupied habitat) in Tennessee and Kentucky, North Fork White Oak Creek (11 river km occupied, 0 river km unoccupied habitat) in Tennessee, New River (14.5 river km occupied, 0 river km unoccupied habitat) in Tennessee, Clear Fork (40 river km occupied, 0 river km unoccupied habitat) in Tennessee, White Oak Creek (10 river km occupied, 0 river km unoccupied habitat) in Tennessee, Bone Camp Creek (6 river km occupied, 0 river km unoccupied habitat) in Tennessee, Crooked Creek (14.5 river km occupied, 0 river km unoccupied habitat) in Tennessee, North Prong Clear Fork (14.5 river km occupied, 0 river km unoccupied habitat) in Tennessee, Sinking Creek (13 river km occupied, 0 river km unoccupied habitat) in Kentucky, Marsh Creek (24 river km occupied, 0 river km unoccupied habitat) in Kentucky, and Laurel Fork (8 river km occupied, 0 river km unoccupied habitat) in Tennessee and Kentucky (USFWS, 2004).

Number of Occurrences: 1 - 20
Number of Occurrences Comments: Presently populations in 12 Cumberland River tributaries are known to exist (in Claiborne, Fentress, Morgan, and Scott Cos., Tennessee; and Whitley, McCreary, and Laurel Cos., Kentucky). Nine of these streams, which comprise the Big South Fork system, may represent a single, viable metapopulation (USFWS, 1997; 2003; 2004). Poor representation in museum collections and only recent recognition as a valid species make assessment of former occurrences difficult. Probably old published accounts of Alasmidonta marginata from above Cumberland Falls were actually Alasmidonta atropurpurea (USFWS, 2003; 2004). This species was recently documented in the Buffalo Creek in the New River basin (Big South Fork Cumberland drainage), Tennessee (Ahlstedt et al., 2008).

Population Size: 2500 - 10,000 individuals
Population Size Comments: The species may be locally abundant at particular sites (e.g., several hundred fresh dead shells were recovered from muskrat middens in an approximately 100 m stretch of North Prong Clear Fork Creek during 1988-1989). Best remaining populations are in the Big South Fork drainage and Marsh Creek, but its distribution is fragmented and often restricted to relatively short stream sections.

Number of Occurrences with Good Viability/Integrity: Very few (1-3)
Viability/Integrity Comments: Sites with good viability include two in McCreary County, Kentucky, and one in Scott County, Tennessee (USFWS, 2003; 2004). Based on sampling conducted in 2002, the populations in two creeks in Fentress and Scott Cos., Tennessee, are among the largest viable populations rangewide (Steve Ahlstedt, pers. comm., 2003, in USFWS, 2004).

Overall Threat Impact: Very high - high
Overall Threat Impact Comments: Much of the information below is derived from and expanded upon in USFWS (2004):
The greatest threat to this species in the Cumberlandian Region is habitat alteration. Principal causes include impoundments, channelization, pollution, and sedimentation that have altered or eliminated those habitats that are essential to the long-term viability of many riverine mussel populations. Impoundments result in the elimination of riffle and shoal habitats, disruption of a river's ecological processes (flooding, loss of bottom stability, bank sloughing), elimination of current and the covering of rocky and sand substrates by fine sediments, and alteration of downstream water quality and riverine habitat. Daily discharge fluctuations, bank sloughing, seasonal oxygen deficiencies, cold-water releases, turbulence, high silt loads, and altered host fish distribution have contributed to limited mussel recruitment and skewed demographics. Impoundments, as barriers to dispersal, contribute to the loss of local populations by blocking postextirpation recolonization. Population losses due to impoundments have probably contributed more to the decline of the Cumberlandian combshell, oyster mussel, and rough rabbitsfoot and most other Cumberlandian Region mussels than any other single factor (as the Cumberland elktoe and purple bean generally inhabit smaller rivers, impoundments have had less of an impact on them, although the impact is still significant).

Dredging and channelization activities have profoundly altered riverine habitats nationwide, with effects on streams. Channel construction for navigation has been shown to increase flood heights thus exacerbating flood events that convey to streams large quantities of sediment with adsorbed contaminants; and channel maintenance may also result in downstream impacts. The entire length of the Tennessee River and much of the Cumberland River is maintained as a navigation channel with a series of locks and dams--nine on the Tennessee River and four on the Cumberland River. Channel maintenance activities continue to cause substrate instability and alteration in these rivers and may serve to diminish what habitat remains for the recovery of riverine species.

Heavy metal-rich drainage from coal mining and associated sedimentation have adversely impacted many stream reaches, destroying mussel beds and preventing natural recolonization. Acid mine runoff may be having local impacts on the recruitment of, particularly, the Cumberland elktoe, since most of its range is within watersheds where coal mining is still occurring. Impacts associated with coal mining activities have particularly altered upper Cumberland River system streams with diverse historical mussel faunas and have been implicated in the decline of Epioblasma species, especially in the Big South Fork. Strip mining continues to threaten mussels in coal field drainages of the Cumberland Plateau with increased sedimentation loads and acid mine drainage, including Cumberland elktoe and Cumberlandian combshell populations. The Marsh Creek population of the Cumberland elktoe has also been adversely affected and is still threatened by potential spills from oil exploration activities. Coal mining activities also occur in portions of the upper Powell and Clinch River systems, primarily in Virginia. Polycyclic aromatic compounds (PAHs) are indicative of coal fines in the bottom sediments of streams. Known to be toxic to mussels and fishes, PAHs have been found at relatively high levels in the upper portions of the Clinch and Powell Rivers in Virginia.

In-stream gravel mining has been implicated in the destruction of mussel populations. Negative impacts include riparian forest clearing (e.g., mine site establishment, access roads, lowered floodplain water table); stream channel modifications (e.g., geomorphic instability, altered habitat, disrupted flow patterns [including lowered elevation of stream flow], sediment transport); water quality modifications (e.g., increased turbidity, reduced light penetration, increased temperature); macroinvertebrate population changes (e.g., elimination, habitat disruption, increased sedimentation); and changes in fish populations (e.g., impacts to spawning and nursery habitat, food web disruptions). Gravel mining activities threaten the Cumberlandian combshell populations in the Powell River and in Buck Creek, the latter stream representing one of only two remaining populations of this species in the entire Cumberland River system. Mining activities on the Elk River may have played a role in the extirpation of the oyster mussel and Cumberlandian combshell from that river.

Contaminants contained in point and nonpoint discharges can degrade water and substrate quality and adversely impact, if not destroy, mussel populations. Although chemical spills and other point sources (e.g., ditch, swale, artificial channel, drainage pipe) of contaminants may directly result in mussel mortality, widespread decreases in density and diversity may result, in part, from the subtle, pervasive effects of chronic low-level contamination. Mussels appear to be among the most intolerant organisms to heavy metals, several of which are lethal, even at relatively low levels. Among other pollutants, ammonia has been shown to be lethal to mussels. Common contaminants associated with households and urban areas, particularly those from industrial and municipal effluents, may include heavy metals, ammonia, chlorine, phosphorus, and numerous organic compounds. Nonpoint-source runoff from urban areas tends to have the highest levels of many pollutants, such as phosphorus and ammonia, when compared to other catchments. Agricultural sources of chemical contaminants are considerable and include two broad categories--nutrients and pesticides. Nutrient enrichment generally occurs as a result of runoff from livestock farms and feedlots and from fertilizers used on row crops. Pesticides, primarily from row crops, are a major source of agricultural contaminants. Pesticide runoff that commonly ends up in streams may have effects (based on studies with laboratory-tested mussels) that are particularly profound.

Numerous Cumberlandian Region streams have experienced mussel kills from toxic chemical spills and other causes. The high number of jeopardized species in the upper Tennessee River system make accidental spills a particular concern to conservationists and resource managers.

Sedimentation, including siltation runoff, has been implicated as the number one factor in water quality impairment in the United States. Specific biological impacts on mussels from excessive sediment include reduced feeding and respiratory efficiency from clogged gills, disrupted metabolic processes, reduced growth rates, increased substrate instability, limited burrowing activity, and physical smothering. Host fish/mussel interactions may be indirectly impacted by changes in stream sediment regimes through three mechanisms: fish abundance, diversity, and reproduction reduced; impedes host fish attractant mechanisms; interfere with the ability of some species' adhesive conglutinates to adhere to rock particles. Waterborne sediment is produced by the erosion of stream banks, channels, plowed fields, unpaved roads, roadside ditches, upland gullies, and other soil disturbance sites. Agricultural activities produce the most significant amount of sediment that enters streams. Silvicultural sedimentation impacts are more the result of logging roads than the actual harvesting of timber.

Developmental activities associated with urbanization (e.g., highways, building construction, infrastructure creation, recreational facilities) may contribute significant amounts of sediment and other pollutants in quantities that may be detrimental to stream habitats. With development, watersheds become more impervious, resulting in increased storm-water runoff into streams and a doubling in annual flow rates in completely urbanized streams. Impervious surfaces may reduce sediment input into streams but result in channel instability by accelerating storm-water runoff, which increases bank erosion and bed scouring. Although not mentioned specifically, this effect could be increased with projected climate change models. Water withdrawals for agricultural irrigation and municipal and industrial water supplies are an increasing concern for all aquatic resources and are directly correlated with expanding human populations. This impact has the potential to be a particular problem for the Cumberland elktoe population in the Big South Fork system and the oyster mussel population in the Duck River.

The alien Asian clam (Corbicula fluminea) was first reported from the Cumberlandian Region around 1959. This species has been implicated as a competitor with native mussels for resources such as food, nutrients, and space, particularly as juveniles. Densities of Asian clams are sometimes heavy in Cumberlandian Region streams, making competition with populations of some of these five species likely. Paradoxically, large, seemingly healthy, populations of unionids may coexist with Asian clams. The invasion of the nonnative zebra mussel (Dreissena polymorpha) poses a threat to the mussel fauna of the Cumberlandian Region. Although zebra mussels are now in the Tennessee and Cumberland River systems, the extent to which they will impact native mussels is unknown. However, as zebra mussels are likely to reach higher densities in the main stems, large tributaries, and below infested reservoirs, native mussels in these areas will likely be more heavily impacted than mussels in smaller streams without upstream reservoirs. Mussel extinctions are expected as a result of the continued spread of zebra mussels in the Eastern United States. Other potential threats from alien species on native mussels include the black carp (Mylopharyngodon piceus), a native of China. If these species invade Cumberlandian Region streams, they could wreak havoc on already stressed native mussel populations. The round goby (Neogobius melanostomus) is another alien invader fish species released in the 1980s into the Great Lakes in ballast waters originating in southeastern Europe. The arrival of round gobies may therefore have important indirect effects on unionid communities through negative impacts to their host fishes.

Exploitation is considered a very minor, albeit historic, threat due to historical harvesting by Native Americans for food and jewelry, and later by North Americans for pearls, pearl buttons, and cultured pearls. Similarly, information on predation and parasitism could potentially be a threat but there is no supporting information thus far although the muskrat (Ondatra zibethicus) has long been recognized in the literature as a significant mussel predator.

The overall threat to this species, posed by piscine and invertebrate predators, in most instances is not thought to be significant. Although parasitism is not thought to be a significant problem in mussels, excessive trematode infestations in their gonads have been implicated in inducing mussel senescence. The harvest of Cumberlandian Region mussel species for commercial purposes is well documented (Anthony and Downing, 2001). It is doubtful, however, that this species has ever been overly exploited for pearling, pearl buttons, cultured pearls, or any other exploitative activity (USFWS, 2004).

Short-term Trend: Decline of 50-70%
Short-term Trend Comments: The number of occurrences and often abundance has declined dramatically (50-70%). The species has apparently been extirpated from the main stems of the Cumberland and Laurel Rivers (and its tributary, Lynn Camp Creek). In addition, no recent records are available for the Collins River (USFWS, 2003; 2004).

Long-term Trend: Decline of 50-90%
Long-term Trend Comments: Number of occurrences and often abundance has declined dramatically with extirpation from main stem of Cumberland River and Laurel River and its tributary, Lynn Camp Creek; while status at the coal-mined New River watershed is unknown (USFWS, 2003; 2004).

Intrinsic Vulnerability: Highly to moderately vulnerable.
Intrinsic Vulnerability Comments: Without the level of genetic interchange these species experienced historically, many small and isolated populations that are now comprised predominantly of adult specimens may be slowly dying out due to various factors. This may, in part, account for the relatively recent demise of numerous tributary populations. Even given the improbable absence of the impacts from current and existing threats, smaller isolated populations of this species may be lost to the devastating consequences of below-threshold effective population size (EPS). Once-sizable populations of many Cumberlandian mussel species occurred throughout significant portions of the main stems of the large rivers and tributary systems comprising the Cumberlandian Region. This was particularly true for the Cumberlandian combshell and oyster mussel. Historically, there were no natural absolute barriers to genetic interchange among their tributary subpopulations and those of their host fishes (with the notable exception of Cumberland Falls. Without the level of genetic interchange these species experienced historically (because of anthropogenic threats), many small and isolated populations that are now comprised predominantly of adult specimens may be slowly dying out due to various factors (USFWS, 2004).

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.

Other NatureServe Conservation Status Information

Inventory Needs: Determine extent and continue to monitor population structure of extant populations. Search to determine if there might be anymore populations in tributaries (particularly small ones) of the Cumberland River above Cumberland Falls.

Protection Needs: Several of the remaining EOs are within the jurisdiction of the US Park Service. However, without protection and management of the applicable portion of the watershed to prevent acid mine run-off, all efforts will be for naught. Critical habitat has been proposed (USFWS, 2003; 2004).

Distribution
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Global Range: (1000-5000 square km (about 400-2000 square miles)) Historically, this species was known only from the Cumberland Plateau province of the upper Cumberland River basin of Kentucky and Tennessee (Parmalee and Bogan, 1998; Cicerello and Schuster, 2003). All verified sites of occurrence are in the Cumberland Plateau Physiographic Province, giving it one of the most restricted ranges of any Cumberlandian species. The few records available indicate that it inhabited the Cumberland River and only tributaries flowing from the south upstream from the hypothesized original location of Cumberland Falls near Burnside, Pulaski County, Kentucky. A single record exists for the Collins River, in the upper Caney Fork River system above Great Falls. It presently (post-1985 records) persists in eight tributaries to the Upper Cumberland River in Kentucky and Tennessee (USFWS, 1998). It is extirpated from the mainstem of the Cumberland River, Laurel River and its tributary, Lynn Camp Creek in Kentucky. Formerly from 19 localities and currently persisting in 12 Cumberland River tributaries (USFWS, 2003; 2004).

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 KY, TN

Range Map
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U.S. Distribution by County Help
State County Name (FIPS Code)
KY Jackson (21109), Knox (21121)*, Laurel (21125), McCreary (21147), Pulaski (21199)*, Rockcastle (21203), Whitley (21235)
TN Fentress (47049), Grundy (47061)*, Morgan (47129), Scott (47151)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
05 Upper Green (05110001)*, Upper Cumberland (05130101)+, Rockcastle (05130102)+, Upper Cumberland-Lake Cumberland (05130103)+, South Fork Cumberland (05130104)+, Collins (05130107)+*, Blue-Sinking (05140104)*
+ 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 freshwater mussel with a somewhat shiny and black shell with greenish rays.
General Description: Shell subovate, thin but not fragile; anterior margin sharply rounded; ventral margin flatly curved, nearly straight, or slightly concave; posterior margin bluntly pointed to somewhat biangulate, junction with dorsum forms a widely obtuse angle; beaks located in anterior 25% of length, project slightly above hinge line, beak sculpture consists of moderately heavy ridges which are indented towards the beak (double-looped) and becoming generally straight distally; posterior ridge well-developed, broad, somewhat rounded but may be rather acute in older individuals, becoming double posteriorly; posterior slope moderately wide, slightly concave proximally, flatted distally, sculpted with corrugations; periostracum smooth, somewhat shiny, yellowish-brown in young to generally black, greenish rays variously developed over surface. Pseudocardinal teeth rather small, pyramidal, compressed, one in right valve, two in left; interdentum reflected upwards into a tooth-like process in left valve; lateral teeth absent or represented by the merest rudiment; beak cavity shallow; anterior and posterior muscle scars confluent, impressed; pallial line continuous, well-marked; nacre shiny, whitish to bluish white, occasionally pinkish or brownish in beak cavity, may be blotched with brown (adapted from Clarke, 1981).
Diagnostic Characteristics: This species is quite similar to ALASMISDONTA MARGINATA, but tends to differ from the latter by its darker color, less pronounced corrugations on the posterior slope, and the less acutely angular development of the posterior ridge. In older individuals of A. ATROPURPUREA, the posterior ridge may be rather high and the resulting slope may be quite steep, but the posterior ridge retains a rounded character. The two species may occur in adjacent stream systems but do not appear to be sympatric at any locality.
Reproduction Comments: The reproductive cycle appears to be similar to that of Alasmidonta marginata, with branchial marsupia charged with embryonic/larval stages between late summer and late spring (see Gordon and Layzer, 1989). Gravid from October through May, but no infested fish until March. Glochidia develop equally well on fin and fills. Native host fish include Cyprinella galactura, Hypentelium nigricans, Ambloplites rupestris, Lepomis megalotis, and Etheostoma caeruleum. Period of glochidial encystment on northern hogsucker, Hypentelium nigricans took 24 days at 66.2 degrees F (Gordon and Lyzer, 1993; USFWS, 2003; 2004).
Ecology Comments: This species seems to exhibit a preference for finer-particle substrates and slow moving currents, although it will occupy other habitats. It appears to be associated with areas dominated by a sandstone geology and poor buffering capacity. It may be locally abundant. In some headwater situations, it may be the only mussel present and may be subjected to heavy predation by muskrats and other mammals.
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: This species is probably rather sessile with only limited movement in the substrate. Passive downstream displacement may occur when mussels are dislodged during floods. Major dispersal occurs while the glochidia are encysted on their hosts.
Riverine Habitat(s): CREEK, High gradient, Low gradient, MEDIUM RIVER, Moderate gradient, Riffle
Special Habitat Factors: Benthic
Habitat Comments: The habitat ranges from small creeks to medium-sized rivers. The mussel is most common in smaller stream habitats. Preferred habitat appears to be shallow flats or pools with slow current and sand substrate with scattered cobble/boulder material, although it will occur in mud or rocky substrates and faster currents (Gordon and Layzer, 1989). Inhabits medium-sized rivers and may extend into headwater streams where it is often the only mussel present. Appears to be most abundant in flats, or shallow pool areas lacking the bottom contour development of typical pools, with sand and scattered cobble-boulder material, relatively shallow depths, and slow (almost imperceptible) currents (USFWS, 2003; 2004).
Adult Food Habits: Detritivore
Immature Food Habits: Parasitic
Food Comments: Larvae (glochidia) of freshwater mussels generally are parasitic on fish and display varying degrees of host specificity. No specific trophic studies have been conducted on this species. General literature claims that mussels are filter-feeders which remove phytoplankton from the water column. These assumptions are based on casual observations of mussels in situ and a few examinations of rectal contents. Baker (1928) speculated that detritus was the primary energy source. This has been substantiated by James (1987) and correlates well with microhabitats observed in the field. This suggests that mussels may occupy a variety of trophic guilds such as postulated for the Sphaeriidae (see Lopez and Holopaien, 1987; Gordon and Layzer, 1989).
Phenology Comments: Little is known concerning phenology of mussels other than when eggs/glochidia are held in the branchial marsupia. Being poikilotherms, activity levels would expectedly be reduced greatly during cold-temperature months.
Length: 10 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Critical habitat has been proposed (USFWS, 2003; 2004). A recovery plan has been published (USFWS, 2004) with recovery objective: delisting.

Recently, critical habitat was designated for Rock Creek (17 river km occupied, 0 river km unoccupied habitat) in Kentucky, Big South Fork (43 river km occupied, 0 river km unoccupied habitat) in Tennessee and Kentucky, North Fork White Oak Creek (11 river km occupied, 0 river km unoccupied habitat) in Tennessee, New River (14.5 river km occupied, 0 river km unoccupied habitat) in Tennessee, Clear Fork (40 river km occupied, 0 river km unoccupied habitat) in Tennessee, White Oak Creek (10 river km occupied, 0 river km unoccupied habitat) in Tennessee, Bone Camp Creek (6 river km occupied, 0 river km unoccupied habitat) in Tennessee, Crooked Creek (14.5 river km occupied, 0 river km unoccupied habitat) in Tennessee, North Prong Clear Fork (14.5 river km occupied, 0 river km unoccupied habitat) in Tennessee, Sinking Creek (13 river km occupied, 0 river km unoccupied habitat) in Kentucky, Marsh Creek (24 river km occupied, 0 river km unoccupied habitat) in Kentucky, and Laurel Fork (8 river km occupied, 0 river km unoccupied habitat) in Tennessee and Kentucky (USFWS, 2004).

Recovery Strategy: The preservation of extant populations and the occupied habitats of these five species is the most immediate and important recovery priority for these mussels. Preservation and protection of these populations will be achieved by continuing to use existing regulatory mechanisms, establishing partnerships with various stakeholders, using best management practices, and minimizing or eliminating threats to the species. Each extant population must also be viable to achieve recovery. Unless a previously unknown population is found, other viable populations within the historic range of each of the five species must be reestablished and protected to effect recovery. Reestablishing new viable populations will require close coordination with and concurrence of the State(s) involved and with other partners that have interests at any potential reintroduction sites. Additional research into the life history and ecological requirements of these mussels as defined in this plan will help formulate the biological information necessary for the preservation of existing or reestablishment and maintenance of other viable populations. Knowledge of the effective population size is particularly critical for determining the size and demographic makeup of a viable population for these species. Due to the rarity of extant populations, propagation of laboratory or hatchery-reared progeny is the most logical means of providing individuals for the establishment of new populations. Facilities that attempt to propagate these mussels should follow the Service's established controlled propagation policy. Priorities for recovery efforts for the five species via propagation should be to develop propagation technology, augment and expand the ranges of extant populations to ensure their viability, and reestablish viable populations in other streams within their historical range that have suitable habitat and water quality. Pursuing and implementing these efforts will enable the recovery of the five species.
Recovery Criteria: Downlisting from endangered to threatened status will occur when the following criteria are met for the protection of extant stream populations, discovery of currently unknown stream populations, and/or reestablishment of historical stream populations: (1) five streams with distinct viable populations of the Cumberland elktoe, six streams with distinct viable populations of the oyster mussel and Cumberlandian combshell, four streams with distinct viable populations of the purple bean, and three streams with distinct viable populations of the rough rabbitsfoot have been established; (2) one distinct naturally reproduced year class exists within each of the viable populations; (3) research studies of the mussels' biological and ecological requirements have been completed and any required recovery measures developed and implemented from these studies are beginning to be successful, as evidenced by an increase in population density of approximately 20 percent and/or an increase in the length of the river reach of approximately 10 percent inhabited by the species as determined through biennial monitoring; (4) no foreseeable threats exist that would likely impact the survival of the species over a significant portion of their ranges; (5) within larger streams the species are distributed over a long enough reach that a single catastrophic event is not likely to eliminate or significantly reduce the entire population in that stream to a status of nonviable; and (6) biennial monitoring of the five species yields the results outlined in criterion (1) above over a 10-year period.
Actions Needed:
1. Utilize existing legislation/regulations to protect current and newly discovered populations.
2. Determine the species' life history requirements and threats and reduce or alleviate those threats which threaten the species.
3. Develop and use an information/education program to solicit the assistance of local landowners, communities, and others to recover the species.
4. Search for additional populations, and through propagation activities, pursue augmentations or reintroductions in order to establish viable populations.
5. Conduct anatomical and molecular genetic analysis of the species to determine the potential occurrence of species complexes or hidden biodiversity.
6. Develop and implement a monitoring program, and annually assess the recovery program where needed.

Biological Research Needs: Determination of sensitivity to pollutants, particularly related to mine effluents, and siltation tolerance.
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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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: 17Nov2011
NatureServe Conservation Status Factors Author: Cordeiro, J.
Management Information Edition Date: 06Oct2005
Management Information Edition Author: Cordeiro, J.
Element Ecology & Life History Edition Date: 17Nov2011
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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  • Anthony, J.L. and J.A. Downing. 2001. Exploitation trajectory of a declining fauna: a century of freshwater mussel fisheries in North America. Canadian Journal of Fisheries and Aquatic Sciences, 58: 2071-2090.

  • Baker, F.C. 1928b. The freshwater Mollusca of Wisconsin: Part II. Pelecypoda. Bulletin of the Wisconsin Geological and Natural History Survey, University of Wisconsin, 70(2): 1-495.

  • Clarke, A.H. 1981b. The tribe Alasmidontini (Unionidae: Anodontinae), Part I: Pegias, Alasmidonta, and Arcidens. Smithsonian Contributions to Zoology 326:1-101.

  • Frierson, L.S. 1927. A Classified and Annotated Checklist of the North American Naiades. Baylor University Press: Waco, Texas. 111 pp.

  • Gordon, M.E. and J.B. Layzer. 1989. Mussels (Bivalvia: Unionoidea) of the Cumberland River review of life histories and ecological relationships. U.S. Fish and Wildlife Service Biological Report, 89(15): 1-99.

  • Gordon, M.E. and J.B. Layzer. 1993. Glochidial host of Alasmidonta atropurpurea (Bivalvia: Unionidae). Transactions of the American Microscopical Society, 112: 145-150.

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

  • James, M.R. 1987. Ecology of the freshwater mussel Hyridella menziesi in a small oliogotrophic lake. Archives of Hydrobiology 108:337-348.

  • 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.

  • Lopez, G.R. and I.J. Holopainen. 1987. Interstitial suspension-feeding by Pisidium spp. (Pisidiiae: Bivalvia): a new guild in lentic benthos? American Malacological Bulletin, 5: 21-29.

  • 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.

  • Parmalee, P.W. and A.E. Bogan. 1998. The Freshwater Mussels of Tennessee. University of Tennessee Press: Knoxville, Tennessee. 328 pp.

  • Parmalee, P.W. and A.E. Bogan. 1998. The freshwater mussels of Tennessee. University of Tennessee Press, Knoxville, Tennesee. 328 pp.

  • 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). 1997. Determination of Endangered Status for the Cumberland Elktoe, Oyster Mussel, Cumberlandian Combshell, Purple Bean, and Rough Rabbitsfoot. Final rule. Federal Register, 62(7): 1647-1658.

  • U.S. Fish and Wildlife Service (USFWS). 1998. Cumberland elktoe (Alasmidontaq atropurpurea), oyster mussel (Epioblasma capsaeformis), Cumberlandian combshell (Epioblasma brevidens), purple bean (Villosa perpurpurea), and rough rabbitsfoot (Quadrula cylindrica strigillata): Technical Draft Recovery Plan. U.S. Fish and Wildlife Service: Asheville, North Carolina. 119 pp.

  • U.S. Fish and Wildlife Service (USFWS). 2003. Agency draft recovery plan for Cumberland elktoe, oyster mussel, Cumberlandian combshell, purple bean, and rough rabbitsfoot. R.S. Butler and R.C. Biggins, eds. U.S. Fish and Wildlife Service, Atlanta, Georgia. 176 pp.

  • U.S. Fish and Wildlife Service (USFWS). 2003. Endangered and Threatened Widlife and plants; proposed designation of critical habitat for five threatened mussels in the Tennessee and Cumberland River basins; proposed rule. Federal Register, 68(106): 33234-33282

  • U.S. Fish and Wildlife Service (USFWS). 2004. Endangered and Threatened Widlife and plants; designation of critical habitat for five endangered mussels in the Tennessee and Cumberland River basins; final rule. Federal Register, 69(168): 53135-53180.

  • U.S. Fish and Wildlife Service (USFWS). 2004. Recovery plan for Cumberland elktoe, oyster mussel, Cumberlandian combshell, purple bean, and rough rabbitsfoot. U.S. Fish and Widlife Service, Atlanta, Georgia. 168 pp.

  • 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.

  • Williams, J. D., A. E. Bogan, R. S. Butler, K. S. Cummings, J. T. Garner, J. L. Harris, N. A. Johnson, and G. T. Watters. 2017. A revised list of the freshwater mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20:33-58.

  • 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
  • Ahlstedt, S., C. Walker, and S. Bakaletz. 2008. Status of freshwater mussels in the coal mining basin of the New River (Big South Fork Cumberland River drainage) in portions of Scott, Anderson, Morgan and Campbell Counties, Tennessee (2006-2008). Ellipsaria, 10(3): 7.

  • Cicerello, R.R. and G.A. Schuster. 2003. A guide to the freshwater mussels of Kentucky. Kentucky State Nature Preserves Commission Scientific and Technical Series 7:1-62.

  • U.S. Fish and Wildlife Service (USFWS). 2004. Endangered and threatened wildlife and plants; 12-month finding for a petition to list the midvalley fairy shrimp as endangered. Federal Register, 69(16): 3592-3598.

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