CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO

AMERICAN WATER RESOURCES ASSOCIATION CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 1 Jess Jones, Steven Ahlstedt, Brett Ostby, Braven Beaty, Michael Pinder, Nathan Eckert, Robert Butler, Don Hubbs, Craig Walker, Shane Hanlon, John Schmerfeld, and Richard Neves 2 ABSTRACT: The Clinch River is located in northeastern (TN) and southwestern Virginia (VA) of the United States, and contains a diverse mussel assemblage of 46 extant species, including 20 species listed as federally endangered. To facilitate quantitative monitoring of the fauna, quadrat data were collected from 2004 to 2009 at 18 sites in the river, including 12 sites in TN and 6 sites in VA. Thirty-eight mussel species were collected alive in total from quadrat samples taken annually at sites in the TN section of the river. Over the five-year study period, mussel density averaged 25.5 m 2 at all sites sampled in TN. In contrast, mussel density averaged only 3.1 m 2 at sites sampled in VA. The best historical site in VA was Pendleton Island in Scott County, where mussel density was estimated as high as 25 m 2 in 1979, comparable to current densities recorded in TN. Mussel densities are now <1 m 2, indicating a collapse of the fauna. A severe reduction in mussel abundance has occurred in a 68-km section of the river from St. Paul, VA, downstream to approximately Clinchport, VA (river kilometers 411.5-343.3). While the environmental factors responsible for the faunal decline are largely unknown, they must have been severe and sustained to reduce such large populations to their current low levels. Long-term water and habitat quality monitoring is needed to determine whether environmental degradation is still occurring in the river. (KEY TERMS: Clinch River; biodiversity hotspot; freshwater mussels; endangered species; mussel population declines.) Jones, Jess, Steven Ahlstedt, Brett Ostby, Braven Beaty, Michael Pinder, Nathan Eckert, Robert Butler, Don Hubbs, Craig Walker, Shane Hanlon, John Schmerfeld, and Richard Neves, 2014. Clinch River Freshwater Mussels Upstream of Norris Reservoir, and Virginia: A Quantitative Assessment from 2004 to 2009. Journal of the American Water Resources Association () 1-17. DOI: 10.1111/jawr.12222 1 Paper No. -13-0107-P of the Journal of the American Water Resources Association (). Received April 30, 2013; accepted December 2, 2013. 2014 American Water Resources Association. Discussions are open until six months from print publication. 2 Restoration Biologist (Jones), Department of Fish and Wildlife Conservation, U.S. Fish and Wildlife Service, Virginia Polytechnic Institute and State University, 106a Cheatham Hall, Blacksburg, Virginia 24061; Biologist (Ahlstedt, Retired), U.S. Geological Survey, Norris, 37828; Biologist (Ostby), Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061; Stewardship Ecologist (Beaty), Clinch Valley Program, The Nature Conservancy, Abingdon, Virginia 24210; Non-game Aquatic Biologist (Pinder), Virginia Department of Game and Inland Fisheries, Blacksburg, Virginia 24060; Biologist (Eckert), Aquatic Wildlife Conservation Center, Virginia Department of Game and Inland Fisheries, Marion, Virginia 24354; Biologist (Butler), U.S. Fish and Wildlife Service, Asheville, North Carolina 28801; Biologist (Hubbs), Wildlife Resources Agency, Camden, 38320; Ecologist (Walker), U.S. Office of Surface Mining and Reclamation, Pittsburgh, Pennsylvania 15220; Biologist (Hanlon), U.S. Fish and Wildlife Service, Abingdon, Virginia 24210; Biologist (Schmerfeld), U.S. Fish and Wildlife Service, Arlington, Virginia 22203; and Research Scientist (Neves, Retired), Department of Fish and Wildlife Conservation, U.S. Geological Survey, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (E-Mail/Jones: jess_jones@fws.gov). 1

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES INTRODUCTION The Clinch River is located in northeastern (TN) and southwestern Virginia (VA), and is known for its high species richness of mussels and fishes (Figure 1). The river is 483-km long and a major headwater tributary of the River. It drains parts of the Ridge and Valley and Cumberland Mountains physiographic provinces of the southern Appalachian Mountains and is considered one of the most diverse freshwater ecosystems in the United States (U.S.) (Neves et al., 1997; Parmalee and Bogan, 1998). Including its network of tributary streams, this river drainage has been impacted by numerous pollution sources over the last 100 years, resulting in increased imperilment for many mussel species. The construction and operation of Norris Dam in TN, completed in 1936 by the Valley Authority (TVA), addressed the need for electricity generation and flood control. The dam eventually rendered the lower ~240 km as unsuitable habitat for most mussel species but the upper half of the river is free-flowing and contains the general hydrological, ecological, and water quality conditions necessary to maintain healthy mussel populations. However, the upper river contains reaches where mussel survival is high and others where it is low, indicating that water quality and physical habitat suitability vary throughout the upper river. Hence, it is likely that the river continues to be affected by a range of anthropogenic impacts, including habitat and water quality degradation from agriculture, forestry, coal mining, urban development, isolated home sewage, FIGURE 1. The 18 Sites Sampled from 2004 to 2009 in the Clinch River, and Virginia, Upstream of Norris Reservoir. Swan Island, upper Frost Ford, and upper Wallens Bend were sampled annually, while the remaining sites were sampled once during the study period. 2

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 poorly treated sewage from wastewater treatment plants, chemical spills, and other human activities (Cairns et al., 1971; Crossman et al., 1973; Ahlstedt et al., 2005). Despite these impacts, the river still contains a diverse mussel assemblage of 46 extant species, including 20 species listed as federally endangered (Table 1). Five additional species are listed as endangered but probably extirpated from the river (one is considered extinct). This brings the total to 24 federally listed mussel species known from the drainage. In addition, five fish species listed as federally endangered or threatened also occur in the river. Thus, not only does the Clinch River contain a rich mussel fauna but it has the highest concentration of extant federally listed aquatic species in the U.S. The first systematic mussel survey of the Clinch River was conducted by A.E. Ortmann over a threeyear period from 1912 to 1915. During this period, he surveyed 16 sites and included data from 10 additional sites surveyed by other investigators. These sites covered the headwaters near Tazewell, Tazewell County, VA, downstream nearly 480 km to Patton s Ferry, Roane County, TN, near the confluence with the River. Adjusting for current taxonomy, he reported 58 mussel species from the river. His results were published as part of a larger monograph on the mussels of the upper River watershed (Ortmann, 1918; Bates and Dennis, 1978). A more than 50-year hiatus in faunal surveys occurred until passage of the Endangered Species Act in 1973 prompted a new series of surveys by TVA biologists and university scientists beginning in the mid-1970s (Stansbery, 1973; Bates and Dennis, 1978; Neves et al., 1980; Ahlstedt, 1986, 1991; Stansbery et al., 1986; Ahlstedt and Tuberville, 1997). Two catastrophic spill events occurred in the upper river near Carbo, VA, at the Appalachian Electric Power (AEP) plant in 1967 (alkaline fly ash spill) and 1970 (sulfuric acid spill), killing fishes, mussels, snails, and aquatic insects for >16 km downstream of the plant (Cairns et al., 1971; Crossman et al., 1973). These and other pollution events, passage of federal and state environmental legislation, and concern over federally listed endangered mussels in the Clinch River (e.g., birdwing pearlymussel [Lemiox rimosus] and other mussel species listed in 1976), began the current era of mussel surveys and biological research that continues to the present day. Available literature and data provide a more detailed historical and contemporary understanding of the distribution and abundance of the fauna, and document some of the major anthropogenic disturbances that have occurred over time. The present condition of the mussel fauna in the Clinch River is characterized by healthy, robust populations in the TN portion of the river and TABLE 1. Scientific and Common Names and Federal Status of Mussel Species in the Clinch River Upstream of Norris Reservoir in and Virginia, Where FE, Federally Endangered and -, No Federal Status. The American Fisheries Society (AFS) status is from Williams et al. (1993), where CS, currently stable; E, federally endangered; T, threatened; V, vulnerable or special concern; X, possibly extinct. In situ status is based on available quantitative and qualitative survey data collected from 1979 to 2009, including this study (see Literature Cited), where, extant; *, very rare; X, possibly extinct; EX, possibly extirpated. Note that the status of some species has changed over the 30-year period. Scientific Name Common Name Federal AFS In Situ (1) Actinonaias Mucket - CS ligamentina (2) Actinonaias pectorosa Pheasantshell - V (3) Alasmidonta marginata Elktoe - V * (4) Alasmidonta viridis Slippershell - V * (5) Amblema plicata Threeridge - CS (6) Cumberlandia Spectaclecase FE E monodonta (7) Cyclonaias tuberculata Purple wartyback - V (8) Cyprogenia stegaria Fanshell FE E (9) Dromus dromas Dromedary FE E pearlymussel (10) Elliptio crassidens Elephantear - V * (11) Elliptio dilatata Spike - V (12) Epioblasma brevidens Cumberlandian FE E combshell (13) Epioblasma Oyster mussel FE E capsaeformis (14) Epioblasma florentina Golden riffleshell FE E aureola (15) Epioblasma haysiana Acornshell - X X (16) Epioblasma lenior Narrow catspaw - X X (17) Epioblasma Cumberland - X X stewardsonii leafshell (18) Epioblasma torulosa Green blossom FE X X gubernaculum (19) Epioblasma triquetra Snuffbox FE T (20) Fusconaia barnesiana pigtoe - V (21) Fusconaia cor Shiny pigtoe FE E (22) Fusconaia cuneolus Finerayed pigtoe FE E (23) Fusconaia subrotunda Longsolid - T (24) Hemistena lata Cracking FE E pearlymussel (25) Lampsilis abrupta Pink mucket FE T (26) Lampsilis fasciola Wavyrayed - CS lampmussel (27) Lampsilis ovata Pocketbook - CS (28) Lasmigona costata Flutedshell - CS (29) Lasmigona holstonia - V heelsplitter (30) Lemiox rimosus Birdwing FE E pearlymussel (31) Leptodea fragilis Fragile papershell - CS EX (32) Lexingtonia Slabside FE E dolabelloides pearlymussel (33) Ligumia recta Black sandshell - V (34) Medionidus Cumberland - T conradicus moccasinshell (35) Pegias fabula Littlewing pearlymussel FE E * (continued) 3

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES Scientific Name TABLE 1. Continued. Common Name Federal AFS In Situ (36) Plethobasus cyphyus Sheepnose FE E (37) Pleurobema cordatum Ohio pigtoe - V (38) Pleurobema oviforme - T clubshell (39) Pleurobema plenum Rough pigtoe FE E (40) Pleurobema rubrum Pyramid pigtoe - T (41) Pleurobema sintoxia Round pigtoe - CS EX (42) Potamilus alatus Pink heelsplitter - CS (43) Ptychobranchus Kidneyshell - V fasciolaris (44) Ptychobranchus Fluted kidneyshell FE E subtentum (45) Quadrula cylindrica Rough rabbitsfoot FE E strigillata (46) Quadrula intermedia Cumberland FE E EX monkeyface (47) Quadrula pustulosa Pimpleback - CS (48) Quadrula sparsa Appalachian FE E * monkeyface (49) Strophitus undulatus Creeper V * (50) Toxolasma lividum Purple lilliput - V EX (51) Truncilla truncata Deertoe - CS * (52) Villosa fabalis Rayed bean FE E EX (53) Villosa iris Rainbow mussel - V (54) Villosa perpurpurea Purple bean FE E (55) Villosa trabalis Cumberland bean FE E EX (56) Villosa vanuxemensis Mountain creekshell - V declining populations in much of the VA reach of the river. These patterns were most likely produced by various historical and contemporary environmental stressors in the upper watershed (Dennis, 1987, 1989; Ahlstedt, 1991; Ahlstedt et al., 2005). Quantitative long-term trend information on populations is critical for determining the status and health of mussel species. Since many mussels are long-lived (e.g., typically 20-50 years), relatively sedentary, and sensitive to various contaminants, they serve as excellent indicators of continuous long-term water quality (Neves et al., 1997; Haag and Rypel, 2011). Healthy populations are characterized by numerous adult cohorts and evidence of recent recruitment (size-classes <20-30 mm), indicative of a stable fauna living in suitable habitat conditions (Jones and Neves, 2011). A key criterion for biologists and natural resource managers is trend analysis for accurately determining whether mussel populations are declining, remaining stable, or increasing in abundance. The purpose of this study was to collect quantitative data from 2004 to 2009 to determine the status and population trends of mussels throughout the Clinch River upstream of Norris Reservoir in both TN and VA. Furthermore, our intent is to ultimately conduct annual sampling for a 10-year period (2004-2014) to provide a time series of population density and shell length frequency data from healthy mussel populations at three sites in TN, and to continue sampling three sites where populations have declined in VA at five-year intervals (2009 and 2014): Speers Ferry, Pendleton Island, and Semones Island, sites first surveyed and then resurveyed by S.A. Ahlstedt since 1979. Datasets will serve as a baseline to gauge future mussel population trends throughout the river. METHODS The study area is a 164.6-km reach of river from river kilometers (RKM) 271.1 in Hancock County, TN, upstream to RKM 435.7 in Russell County, VA (Figure 1). The preferred habitat of most mussel species is shallow water (<1 m) sections containing gravel shoals, which served as sample sites for our survey. This habitat is abundant in the river but interspersed with longer, slower-flowing deeper pools (>1 RKM) containing poor quality mussel habitat. Typical lengths of gravel shoals in this reach are about 100-200 m but occasionally longer. The river features moderate gradient with riffle-run fluvial morphology. Mussel population densities were analyzed at 18 sites in the Clinch River in TN (12 sites) and VA (6 sites) from 2004 to 2009 (Figure 1; Table 2). All sampling was conducted in late summer or early fall when water levels were low, and young-of-the-year and older juvenile mussels had reached sizes adequate for detection (e.g., >10 mm). Sites were sampled once during the study period, except for three TN sites, Wallens Bend (WB), Frost Ford (FF), and Swan Island (SI), which were sampled annually. These sites were selected because they represent the upper (RKM 309.6), middle (RKM 291.8), and lower (RKM 277.1) locations of the TN section of the river where healthy mussel populations remain. Upstream and downstream limits of sampling sites are very discrete in the river and were determined by visually inspecting substrate composition (e.g., noting an abrupt change from suitable gravel substrate to unsuitable bedrock or soft sediments), water depth, flow velocity, and general absence of mussels. The same upstream and downstream boundaries were used at sites sampled annually. Small, exposed gravel bars and islands without mussels but within the immediate shoal area were measured and subtracted from analysis. Site dimensions (length and width) were measured using a standard 100 m measuring 4

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 TABLE 2. Sampling Site, Area Size, and Mussel Density at Sites Sampled from 2004 to 2009 in the Clinch River, and Virginia. Site Location Name River Kilometer (River Mile) Total Site Area (m 2 ) Year(s) Sampled No. (n) 0.25 m 2 quadrats yr 1 Mean Density m 2 (SE) Lower 95% CI Upper 95% CI (1) Swan Island, (2) Briery Creek, (3) Sneedville, (4) Falls Branch, (5) Frost Ford, (6) Frost Ford, (7) Little E. Island, (8) Brooks Island, (9) Webb Island, (10) Kyles Ford, (11) Wallen Bend, (12) Wallen Bend, (13) Speers Ferry, Virginia (14) Clinchport, Virginia (15) Slant, Virginia (16) Pendleton Island, Virginia (17) Semones Island, Virginia (18) Cleveland Islands, Virginia 277.1 (172.2) 5,760 2004 60 23.7 (4.1) 15.7 31.7 2005 60 15.1 (3.2) 8.8 21.4 2006 60 16.3 (3.4) 9.6 23.0 2007 60 22.5 (3.1) 16.4 28.6 2008 60 23.1 (4.8) 13.7 32.5 2009 72 28.2 (3.9) 20.6 35.8 280.8 (174.5) 6,600 2006 40 12.0 (1.6) 8.9 15.1 287.6 (178.7) 2,016 2006 40 11.8 (1.6) 8.5 15.0 288.7 (179.4) 5,334 2006 40 34.9 (4.3) 26.4 43.2 291.3 (181.0) 8,600 2007 72 9.2 (1.0) 7.2 11.2 291.8 (181.3) 15,050 2004 60 31.4 (2.2) 27.0 35.8 2005 60 24.2 (2.1) 20.1 28.3 2006 60 27.1 (2.3) 22.6 31.6 2007 60 45.9 (3.8) 38.5 53.3 2008 60 68.4 (4.9) 58.8 78.0 2009 91 42.9 (3.0) 37.0 48.8 293.7 (182.5) 11,200 2005 60 19.3 (1.6) 16.2 22.4 295.3 (183.5) ~6,000 2005 60 21.5 (4.0) 13.6 29.2 301.7 (187.5) 4,576 2006 60 22.8 (2.2) 18.4 27.2 305.1 (189.6) ~15,000 2004 146 43.8 (4.1) 35.8 51.8 309.5 (192.3) 16,933 2007 120 22.0 (1.7) 18.7 25.4 309.6 (192.4) 3,182 2004 60 13.7 (1.4) 10.9 16.5 2005 60 12.9 (1.4) 10.2 15.6 2006 60 15.1 (1.5) 12.2 18.0 2007 60 21.3 (1.7) 18.0 24.6 2008 60 30.2 (3.2) 23.8 36.6 2009 60 28.5 (2.7) 23.2 33.8 339.7 (211.1) ~4,000 2009 80 5.0 (0.7) 3.6 6.4 343.1 (213.2) 10,173 2006 220 1.9 (0.2) 1.6 2.2 359.7 (223.5) 9,000 2005 201 3.8 (0.3) 2.6 5.0 364.2 (226.3) ~20,000 1 2009 360 0.66 (0.1) 0.5 0.9 378.3 (235.1) ~10,000 2009 124 0.61 (0.2) 0.3 0.9 435.7 (270.8) 16,930 2008 478 6.6 (0.4) 5.9 7.3 1 Estimate includes area for the left descending channel only. tape. Quantitative data were collected by systematic 0.25 m 2 quadrat samples on transect lines placed perpendicular along the width of the river. Both transects and quadrats were evenly spaced throughout the delineated shoal area. Total area (m 2 ) of the sample sites was determined by multiplying mean river width, measured at 10-20 m intervals, by total length of the reach (Table 2). Quarter meter quadrats were delineated using a 0.5 m 9 0.5 m frame constructed of 12 mm diameter rebar welded at the corners. Using a mask and snorkel, surveyors visually searched for mussels while excavating substrate approximately 20 cm in depth within each quadrat. Live mussels were collected from quadrat excavations and placed in a mesh bag and brought to the river bank for identification and measurement. Mussels 5

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES were identified to species and measured for total shell length anterior-posterior (nearest 0.1 mm) using digital calipers and returned to their approximate position of collection. Population densities (N/m 2 ) were calculated from the means of the quadrat samples at each site. A generalized linear model (GLM) was used to test for significance of trends in the time series data collected from 2004 to 2009 at WB, FF, and SI. The model was implemented using the program R (R Development Core Team, 2006). RESULTS Quadrat samples showed significant differences in mussel abundance between the TN and VA reaches of river; mussel populations in TN continue to maintain high density levels, while populations in VA occur at much lower levels. At the three sites sampled annually in TN (SI, FF, WB), mussel density averaged 27.2 m 2 and significantly (p < 0.001) increased over time at two sites (Figure 2). Over the five-year study period, mussel density averaged 25.5 m 2 at all 12 sites sampled in TN (Table 2). In contrast, mussel density averaged 3.1 m 2 at all six sites sampled in VA. The best historical site in VA was Pendleton Island in Scott County, where mussel densities are now <1 m 2. Mussel density at this site was as high as 25 m 2 in 1979 (Ahlstedt et al., 2005), comparable to the current mean density in TN. Further upstream, mussel populations at Cleveland Islands (RKM 435.7) appear to be stable, where mussel density averaged 6.6 m 2, recruitment of multiple species was evident, and diversity was 23 species (Eckert and Pinder, 2010). Section of the Clinch River A total of 38 mussel species were collected alive in quadrat samples conducted at the 12 sites in the TN section of the Clinch River, including 28 species at SI (RKM 277.1), 27 at FF (RKM 291.8), and 25 at WB (RKM 309.6) (Table 3). Abundance was generally highest at FF, reaching a mean density of 68.4 m 2 in 2008. Falls Branch (RKM 288.7), Kyles Ford (RKM 305.1), and WB also reached mean densities >30.0 m 2 over the study period (Tables 2 and 3; Figure 2). Six lampsiline species were common, typically occurring at >1 m 2 per site and comprised >90% of the relative abundance at investigated sites: Medionidus conradicus (25.5%), Epioblasma capsaeformis (22.9%), Actinonaias pectorosa (15.4%), Ptychobranchus subtentum (12.3%), Actinonaias ligamentina FIGURE 2. Estimates of Mean Mussel Density Using a Systematic Survey Design at Sites Sampled from 2004 to 2009 in the Clinch River, and Virginia. Error bars represent 95% confidence intervals, where nonoverlapping intervals among sites or sample years indicate significant (p < 0.05) differences. Broken line is the mean of all sites. (9.4%), and Ptychobranchus fasciolaris (3.1%) (Table 3; Figure 3). Based on their size-class frequency distributions, these six species have been recruiting consistently in this section of river during the study period, with smaller, younger mussels well represented in samples (Figure 4). Individuals of the relatively short-lived M. conradicus and E. capsaeformis <20-30 mm are typically less than three to four years old (Scott, 1994; Jones and Neves, 2011), while individuals <50-70 mm of the latter four relatively long-lived species are typically less than four to five years old (Scott, 1994; Henley et al., 2001). Furthermore, densities of these six species varied among sites and years (Figure 5). For example, among the three annually sampled sites, density of A. pectorosa (3.0-5.8 m 2 ) and A. ligamentina (5.5-10.8 m 2 ) was highest at SI but occurred at lower and similar levels (1-2 m 2 ) at FF and WB. In contrast, mussel densities of E. capsaeformis (6-40 m 2 ) and M. conradicus (9.2-15.0 m 2 ) were highest at FF, followed by WB and then lowest at SI. Densities of P. fasciolaris (0.3-1.7 m 2 ) and P. subtentum (1.4-4.1 m 2 ) were similar among sites but uneven over time. All other species 6

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 TABLE 3. Abundance of Live Mussels for Species Sampled during Quantitative Surveys Conducted at Swan Island (SI), Frost Ford (FF), and Wallens Bend (WB) and Other Sites (see Table 2) from 2004 to 2009 in the Clinch River,. Scientific Name SI (277.1) FF (291.8) WB (309.6) Other Sites All Sites (1) Actinonaias ligamentina 401 173 148 318 1,040 (2) Actinonaias pectorosa 759 189 217 533 1,698 (3) Alasmidonta marginata 1 0 0 0 1 (4) Amblema plicata 1 0 1 0 2 (5) Cumberlandia monodonta 0 0 0 1 1 (6) Cyclonaias tuberculata 11 35 18 24 88 (7) Cyprogenia stegaria 12 13 1 10 36 (8) Dromus dromas 84 62 2 26 174 (9) Elliptio dilatata 2 68 68 77 215 (10) Epioblasma brevidens 40 51 30 59 180 (11) Epioblasma capsaeformis 80 1,616 363 464 2,523 (12) Epioblasma triquetra 15 4 2 8 29 (13) Fusconaia barnesiana 1 1 0 1 3 (14) Fusconaia cor 0 1 5 1 7 (15) Fusconaia cuneolus 0 7 13 4 24 (16) Fusconaia subrotunda 8 19 5 32 64 (17) Hemistena lata 9 28 0 21 58 (18) Lampsilis fasciola 18 28 34 52 132 (19) Lampsilis ovata 11 6 3 8 28 (20) Lasmigona costata 3 1 1 5 10 (21) Lemiox rimosus 1 15 8 17 41 (22) Lexingtonia dolabelloides 0 0 0 1 1 (23) Ligumia recta 1 0 1 1 3 (24) Medionidus conradicus 167 1,105 574 973 2,819 (25) Plethobasus cyphyus 2 16 1 8 27 (26) Pleurobema cordatum 1 0 0 0 1 (27) Pleurobema oviforme 0 1 1 0 2 (28) Pleurobema plenum 0 14 0 7 21 (29) Pleurobema rubrum 1 0 0 0 1 (30) Potamilus alatus 0 0 0 1 1 (31) Ptychobranchus fasciolaris 114 71 43 117 345 (32) Ptychobranchus subtentum 267 313 263 519 1,362 (33) Quadrula cylindrica strigillata 1 5 1 6 13 (34) Quadrula pustulosa 3 0 0 4 7 (35) Strophitus undulatus 0 1 0 3 4 (36) Truncilla truncata 0 0 0 1 1 (37) Villosa iris 1 20 21 29 71 (38) Villosa vanuxemensis 0 0 0 1 1 Total 2,015 3,863 1,824 3,332 11,034 were uncommon or rare in TN, typically occurring at <1 m 2 per site, and collectively comprised <10% of total abundance. While the following species were not as abundant as those listed above, recruitment was observed in TN for many of the federally listed endangered mussels, including Cyprogenia stegaria, Dromus dromas, Epioblasma brevidens, E. triquetra, Hemistena lata and even for some of the rarest endangered species such as L. rimosus, Fusconaia cor, F. cuneolus, Pleurobema plenum, and Quadrula cylindrica strigillata. This also includes many of the nonlisted but uncommon mussels: Cyclonaias tuberculata, Elliptio dilatata, Fusconaia subrotunda, Lampsilis fasciola, and Lampsilis ovata. A few species were collected alive in quadrats but are considered very rare at sites in TN, including Alasmidonta marginata, Amblema plicata, Cumberlandia monodonta, Fusconaia barnesiana, Lexingtonia dolabelloides, Ligumia recta, Pleurobema cordatum, Pleurobema oviforme, Pleurobema rubrum, Potamilus alatus, Strophitus undulatus, and Truncilla truncata (Table 3). These mussels were represented by only one to a few individuals in quadrat samples and currently show low to no recorded recruitment. Virginia Section of the Clinch River A total of 26 mussel species were collected alive in quadrat samples conducted at sites in the VA section of the Clinch River, including 14 species at Speers Ferry (RKM 339.7), 14 at Clinchport (RKM 343.1), 18 at Slant (RKM 359.7), 14 at Pendleton Island (RKM 364.2), 4 at Semones Island (RKM 378.3), and 19 at 7

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES FIGURE 3. Relative Abundance of Mussel Species: (A) Clinch River, from 2004 to 2009 and (B) Clinch River, Virginia in 2009. Abundance was estimated by pooling data from all sampled sites in each section of the river. Cleveland Islands (RKM 435.7) (Table 4). Abundance was highest at Cleveland Islands (6.6 m -2 ) and lowest at Semones Island (0.61 m 2 ) and Pendleton Island (0.66 m 2 ) (Table 2). Five species comprised most of the relative abundance at investigated sites: A. pectorosa (29.8%), M. conradicus (19.2%), E. dilatata (11.1%), A. ligamentina (10.7%), and P. fasciolaris (8.1%) (Table 4). Based on observed size-class frequency distributions, these five species show low to minimal evidence of recruitment in the section of river from RKM 343.1-378.3, with smaller, younger mussels poorly represented in samples (Eckert et al., 2008a, b). However, recruitment of these and some other species is evident upstream at Cleveland Islands (RKM 435.7), where E. capsaeformis was augmented to RKM 435.7 from 2006 to 2010. DISCUSSION General Patterns of Mussel Abundance in the Clinch River The mussel fauna of the Clinch River upstream of Norris Reservoir currently is characterized by higher abundance in the TN section of the river and lower abundance in most VA sections of the river, especially the vicinity of Pendleton and Semones Islands. While the pattern of abundance in TN is reflective of healthy and diverse populations that have received no significant perturbations over time, the pattern in VA is more complex and indicative of varied historical and contemporary (e.g., within the last 10 years) impacts (Figure 6). Most importantly, a severe reduction in mussel abundance has occurred in a 68-km section of the river in VA in the vicinity of St. Paul downstream to approximately Clinchport (Clinch River kilometers 411.5 to 343.3). This section now is arguably a mussel dead-zone, i.e., an area where abundance is far below normal, little to no recruitment is evident for most species, and most remaining mussels are typically older individuals. Further upstream, a 19.6-km section of river from Nash Ford (RKM 449.8) downstream to Carbo (RKM 431.1), which includes Cleveland Islands (RKM 435.7), contains a moderately abundant and diverse mussel assemblage with recruitment observed for most species (Ostby, 2005; Eckert and Pinder, 2010). This relatively short river section has somewhat healthy mussel populations, indicating that the severity and types of impacts to this section are most likely different from those further downstream in the dead-zone. Downstream from Cleveland Islands is the AEP plant near Carbo, where two major contaminant spills occurred. While mussel density is low (~1.0 m 2 ) from the power plant downstream to the bridge at Carterton, VA (RKM 424.8), 15 extant species recently have been documented there, including young individuals of several species (Ahlstedt et al., 2009). The presence of young mussels is encouraging and a sign that water quality conditions have improved over time in this part of the river. Finally, the lowermost VA section from below Clinchport (RKM 343.1), from around Speers Ferry (RKM 339.7), downstream to the stateline (RKM 325.2) also appears to be in recovery, with mussel densities at moderate levels (5-10 m 2 ) and recruitment observed for many species. Sections in the river where mussel abundance remains moderate to high from Nash Ford downstream to Carbo and Speers Ferry downstream into TN are far enough downstream from pollution sources that mussel populations have been spared severe and long-lasting impacts. Although not part of the current study, the uppermost section of the river from its origin at Tazewell, VA (RKM 564.1) downstream to just above Cedar Bluff, VA (RKM 521.4) was surveyed in 1999 for mussels by Jones et al. (2001), who documented declines in species richness and abundance based on current and historical occurrence records of mussels in Tazewell County. While the historical and contemporary sources of pollution responsible for population 8

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 FIGURE 4. (A) Length Frequency Histograms of the Six Most Abundant Species Sampled from 2004 to 2009 in the Clinch River,. declines in VA are not well documented, it is likely that they are varied and emanate from multiple sources over time and place. A large point-source pollution event is unlikely to explain the current pattern of mussel declines in the VA portion of the river. Healthy Mussel Populations in The mussel fauna in the TN section of the river is one of the best examples in the U.S. of a healthy species assemblage, characterized by high diversity, high abundance, and regular recruitment (Jones and Neves, 2011). Thirty-eight species were documented in TN during our study. This section also harbors the largest remaining populations globally of nine federally listed endangered species: D. dromas, E. brevidens, E. capsaeformis, E. triquetra, H. lata, Fusconaia cor, F. cuneolus, P. subtentum, and Q. cylindrica strigillata. While a few scattered and small populations of these species remain in other rivers, the Clinch River by far harbors the largest sustainable populations range-wide. In addition, populations of C. monodonta, C. stegaria, L. rimosus, Plethobasus cyphyus, and P. plenum in the river are showing signs of recovery and also represent some of the most robust range-wide. All of these populations are critical to each species survival, as they will serve as 9

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES FIGURE 4. Continued. (B) Length frequency histograms of the six most abundant species sampled in 2009 in the Clinch River, Virginia. the primary source populations to conduct anticipated recovery actions in the region, including translocations of adults to other rivers and collection of adult broodstock for rearing propagated mussels in hatcheries. Both wild and hatchery-produced sources of mussels are important because they allow for reestablishment of populations outside of the Clinch River. Revitalizing small populations and establishing new ones through augmentations and reintroductions, respectively, meet objectives outlined in the respective federal recovery plan for each species. Furthermore, the large populations (>1 million individuals per species) of nonlisted mussels in the river, such as A. ligamentina, A. pectorosa, and M. conradicus, in particular provide a range of ecosystem services to people living in the watershed (e.g., filtering millions of gallons of water per day) that promotes swimming and fishing, sustains a high quality source for drinking water, and enhances productivity of aquatic insects, crayfishes, and many types of fishes for recreational use (Spooner and Vaughn, 2006). Our study collected annual samples at three sites, SI, FF, and WB, for a five-year period, with the intent to assess trends from the most abundant populations in the river. Monitoring will continue until 2014, eventually creating a 10-year dataset for these populations. This information is important and will serve as a baseline to compare future abundance 10

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 FIGURE 5. Estimates of Mean Mussel Density of the Six Most Abundant Species Sampled Annually from 2004 to 2009 in the Clinch River,. Error bars represent 95% confidence intervals, where nonoverlapping intervals among sites or sample years indicate significant (p < 0.05) differences. Data from 2004 to 2008 for Epioblasma capsaeformis was previously published in Jones and Neves (2011). levels at these and other sites, such as those in VA where continued monitoring will be needed to determine population trends. Furthermore, the datasets are beginning to reveal differences among species. For example, abundances of E. capsaeformis and M. conradicus generally exhibited upward trends over the five-year period and were greater than other species, especially at FF and WB (Figures 2 and 5). Population increases in these two species contributed to most of the increase in the assemblage-level abundance at these sites over the study period. Knowledge of population trends at the species level will give biologists a better understanding of which species are likely to fluctuate greatly over time versus those that are more stable in abundance, and will provide insight into appropriate criteria for recovery efforts. At least two more species occur in the TN section of the river, Elliptio crassidens and Lampsilis abrupta. Elliptio crassidens was once common but is now very rare, likely due to low recruitment because of declines in its migratory fish host in the study area. Remaining individuals are large and old but sporadically collected alive in the TN and VA sections (Jess Jones and Steven Ahlstedt personal observation). The species can live to at least 70 years old and thought to use skipjack herring (Alosa chrysochloris) 11

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES TABLE 4. Abundance of Live Mussels for Species Sampled during Quantitative Surveys Conducted at Speers Ferry (SF), Clinchport (CP), Slant (S), Pendleton Island (PI), Semones Island (Sem. I), and Cleveland Islands (CI) from 2004 to 2009 in the Clinch River, Virginia. Scientific Name SF 339.7 CP 343.1 1 S 359.7 2 PI 364.2 Sem. I 378.3 CI 435.7 3 All Sites (1) Actinonaias ligamentina 6 31 78 15 2 0 132 (2) Actinonaias pectorosa 15 16 37 10 8 282 368 (3) Amblema plicata 0 1 4 4 0 4 13 (4) Cumberlandia monodonta 0 0 1 0 0 0 1 (5) Cyclonaias tuberculata 4 6 14 4 0 1 29 (6) Elliptio dilatata 3 1 8 1 0 124 137 (7) Epioblasma brevidens 8 17 0 1 0 0 26 (8) Epioblasma capsaeformis 0 0 0 0 0 14 4 14 (9) Fusconaia barnesiana 0 0 2 0 0 10 12 (10) Fusconaia cor 0 0 2 1 0 12 15 (11) Fusconaia cuneolus 0 0 0 0 0 1 1 (12) Fusconaia subrotunda 2 1 7 0 0 6 16 (13) Lampsilis fasciola 4 7 4 1 1 21 38 (14) Lampsilis ovata 1 1 0 0 0 0 2 (15) Lasmigona costata 0 0 1 0 0 2 3 (16) Lemiox rimosus 0 0 1 1 0 0 2 (17) Lexingtonia dolabelloides 1 0 0 0 0 1 2 (18) Medionidus conradicus 35 8 1 1 0 193 238 (19) Plethobasus cyphyus 1 1 1 0 0 0 3 (20) Pleurobema oviforme 0 0 0 0 0 8 8 (21) Potamilus alatus 0 0 0 1 0 0 1 (22) Ptychobranchus fasciolaris 11 13 15 10 8 43 100 (23) Ptychobranchus subtentum 5 6 0 0 0 18 29 (24) Quadrula c. strigillata 0 0 1 1 0 1 3 (25) Villosa iris 4 1 5 7 0 22 39 (26) Villosa vanuxemensis 0 0 2 0 0 2 4 Total 100 110 184 58 19 765 1,236 1 Data collected by Eckert et al. (2008b). 2 Data collected by Eckert et al. (2008a). 3 Data collected by Eckert and Pinder (2010). 4 Species was reintroduced to site from 2006 to 2010. as a fish host, which was recently confirmed as a suitable host by laboratory research conducted at Auburn University, Alabama (Howard, 1914; Hauswald, 1997; James Stoeckel, Auburn University, personal communication). The completion of Norris Dam in 1937 has prevented numerous migratory fish species including A. chrysochloris and other clupeids access to the Clinch River in sufficient numbers to allow for sustainable recruitment of E. crassidens. This and other once common species, e.g., Leptodea fragilis and T. truncata, may ultimately become extirpated from the river because their fish hosts (e.g., freshwater drum, Aplodinotus grunniens) now occur at densities too low to sustain recruitment. Lampsilis abrupta has been collected alive from the river in the last few decades in both states, and was last observed in TN in 1995 downstream of Sneedville at RKM 287.6 (Steven Ahlstedt, personal communication). Furthermore, the species remains part of the extant fauna as a result of biologists from Virginia Department of Game and Inland Fisheries releasing >1,000 sub-adult hatchery-reared individuals at sites in VA in 2011. Two other species also may occur in the TN section of the river purple bean (Villosa perpurpurea) and purple lilliput (Toxolasma lividus) but have not been collected alive in decades, although shells of both species have been collected upstream of Sneedville in the last 10-20 years (Jess Jones and Steven Ahlstedt, personal observation). Collapse of the Mussel Fauna at Pendleton Island, Virginia A total of 46 mussel species have been collected at Pendleton Island, VA, since 1979, of which 42 species were based on samples of live individuals and another 4 from collection of shells only (Table 5). To our knowledge, this is the highest recorded species richness at a single site in North America in recent decades. From the 1930s to the 1970s, the widespread construction of dams throughout the Ohio River valley, especially those in the and Cumberland River subbasins where diversity was historically very high (>60 species at some sites), has caused major faunal changes and directly resulted in the extinction of numerous species (Haag, 2009). Some of the rarest species in the river were known from 12

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 FIGURE 6. Reaches in the Clinch River, Virginia where Mussel Populations Are in Decline and Currently at Low-Density Levels (<1 m 2 ), and Where Populations Are Stable and at Higher Density Levels (>5 m 2 ). In reaches 1 (RKM 449.8 to 431.1) and 4 (RKM 343.3 to 325.2) populations are stable and at higher densities, in reach 2 (RKM 431.1 to 411.5) mussel density is low but recruitment of multiple species is evident, and in reach 3 (RKM 411.5 to 343.3) populations are in decline with little evidence of recruitment. Pendleton Island, including L. abrupta, H. lata, Quadrula intermedia, Quadrula sparsa, and V. perpurpurea (Figure 7). The last known live individual of Epioblasma torulosa gubernaculum was collected at the site in 1983, a large, old male >50 mm (Richard J. Neves, personal observation). This species was once abundant at the site, as relic shells of the species are still relatively common there, but is now considered extinct. Although the endangered scaleshell (Leptodea leptodon) is not known from Pendleton Island or other reaches of the upper Clinch River, a record and shell (male 89-mm long) of the species does exist for Scott County, VA; the specimen is at the U.S. National Museum (USNM 150158) and a photograph can be viewed in Williams et al. (2008). While no specific locality information is provided for this record, Ortmann (1918) did record the species from the upper River basin in both the Holston and lower Clinch rivers, suggesting that the shell could have been collected in the Scott County section of either the Clinch or North Fork Holston River. Available data (Ahlstedt and Tuberville, 1997; Ahlstedt et al., 2005) and observations made by other biologists (e.g., R.J. Neves) clearly indicate that mussel abundance at Pendleton Island in the late 1970s 13

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES TABLE 5. Mussel Species Sampled at Pendleton Island in the Clinch River, Scott County, Virginia. Data are from: A, Dennis (1989); B, Ahlstedt et al. (2005); C, The Nature Conservancy (1994-1995); D, Virginia Tech shell collection; E, Collected alive by R.J. Neves (personal observation). Scientific Name Live Shell Data Sources (1) Actinonaias ligamentina X X A, B, C (2) Actinonaias pectorosa X X A, B, C (3) Alasmidonta marginata X X C, E (4) Amblema plicata X X A, B, C (5) Cumberlandia monodonta X C (6) Cyclonaias tuberculata X X A, B, C (7) Cyprogenia stegaria X X A, C, E (8) Dromus dromas X E (9) Elliptio crassidens X B (10) Elliptio dilatata X X A, B, C, D (11) Epioblasma brevidens X X C, D, E (12) Epioblasma capsaeformis X X B, D, E (13) Epioblasma torulosa gubernaculum X X D, E (14) Epioblasma triquetra X X A, C, E (15) Fusconaia barnesiana X X A, B, C, D (16) Fusconaia cor X X A, B, C, D (17) Fusconaia cuneolus X X A, B, C, D (18) Fusconaia subrotunda X X A, B, C, D (19) Hemistena lata X X C, D, E (20) Lampsilis abrupta X D (21) Lampsilis fasciola X X A, B, C, D (22) Lampsilis ovata X X A, B, D (23) Lasmigona costata X X A, B, C, D (24) Lemiox rimosus X X A, B, C, D (25) Leptodea fragilis X X A, B, D (26) Lexingtonia dolabelloides X X A, C, D (27) Ligumia recta X X A, B, C, D (28) Medionidus conradicus X X A, B, C, D (29) Plethobasus cyphyus X X A, B, C, D (30) Pleurobema cordatum X A (31) Pleurobema oviforme X X A, C, D (32) Pleurobema rubrum X X B, C, D, E (33) Potamilus alatus X X A, B, C, D (34) Ptychobranchus fasciolaris X X A, B, C, D (35) Ptychobranchus subtentum X X A, B, C, D (36) Quadrula cylindrica strigillata X X A, B, C, D (37) Quadrula intermedia X X D, E (38) Quadrula pustulosa X X A, D (39) Quadrula sparsa X X D, E (40) Strophitus undulatus X C, D (41) Truncilla truncata X A, C, D (42) Villosa fabalis X D (43) Villosa iris X A, B, C, D (44) Villosa perpurpurea X B, C, D (45) Villosa trabalis X A (46) Villosa vanuxemensis X X B, C, D and early 1980s was similar to levels now seen at sites in the TN section of the river. However, the fauna at the site has collapsed during the last 30 years, going from 25.0 to <1.0 mussel m 2, an estimated 96% decline in density (Figure 8). While the factors responsible for this faunal decline remain unknown, they must have been severe and sustained to reduce such large populations to their current low levels. While identifying the initial date of the decline is not possible, it is commonly accepted that the 1967 and 1970 spills at the AEP plant were severe, killing both mussels and their fish hosts for >16 km downstream (Cairns et al., 1971; Crossman et al., 1973; Jenkins and Burkhead, 1993). The spills not only caused mortality of adult and juvenile mussels but reduced juvenile recruitment for an unknown time period from loss of fish hosts and potentially from residual sediment toxicity. These spills occurred about 10 years before the first quantitative sampling was conducted at the site in 1979. It is likely these spills and other sources of pollution beginning in the 1960s were the first major impacts to this section of the river. If for example, severe and sustained water pollution had occurred a decade or more earlier, the abundance and diversity of the mussel fauna at Pendleton Island (based on 1979 collection records) probably would have declined, similar to the population levels we see today. Furthermore, it seems unlikely that the spills at the AEP plant were the sole cause of the mussel decline at the site. Again, the fauna was reasonably intact about a decade after the spills, but continued to decline through the 1980s and especially during the 1990s and 2000s. The most plausible scenario for the decline of mussel populations at Pendleton Island and other sites in the river from RKM 431.1 downstream to RKM 343.3 is that multiple sources of pollution sustained over a period of at least several decades since the 1960s contributed to a steady downward spiral of the fauna. It remains unclear whether these or new pollution sources affect the fauna today; however, because mussel abundance remains low and there is little to no recruitment for most species, the fauna is not showing signs of recovery in this reach. Thus, the documented decline of the mussel fauna at Pendleton Island is a relatively recent phenomenon, occurring primarily after passage of major state and federal environmental laws in the early 1970s. Conservation Implications The Clinch River is arguably the most important river in the U.S. for conservation of native freshwater mussels, because of the high number of federally listed endangered species (20 species) that remain extant there. The largest, and in many cases the only, stronghold population remaining of nearly half of these species occur in this river. The river s rich fauna of mussels, snails, fishes, and crayfishes is globally significant and one of the most diverse at a temperate latitude. Unfortunately, the mussel fauna in a 68-km section of the river in VA is in decline. 14

CLINCH RIVER FRESHWATER MUSSELS UPSTREAM OF NORRIS RESERVOIR, TENNESSEE AND VIRGINIA: A QUANTITATIVE ASSESSMENT FROM 2004 TO 2009 FIGURE 7. Shells of Endangered Mussel Species Collected from Pendleton Island (RKM 364.2), Clinch River, Virginia. Photographs are of: (A) Quadrula sparsa, 68.4-mm long, collected July 29, 1982; (B) Quadrula intermedia, 68.4-mm long, collected July 29, 1982; (C) Villosa perpurpurea, 58.2 mm (top), 57.9 mm (middle), 50.3 mm (bottom), collected June 13, 1983; (D) Hemistena lata, 84.2 mm (top), 77.0 mm (bottom), collected August 4, 1983; (E) Lampsilis abrupta, 92.5 mm, collected April 8, 1983; (F) Dromus dromas (live individual), ~70 mm, sampled June 23, 1982. All shells were collected by R.J. Neves and are available in the shell collection at the Freshwater Mollusk Conservation Center, Virginia Tech. FIGURE 8. Time Series Plot of Mean Mussel Density from 1979 to 2009 at Pendleton Island, Clinch River, Virginia; Data from 1979 to 2004 Were Collected by Ahlstedt et al. (2005) Using a Random Survey Design. Error bars represent 95% confidence intervals, where nonoverlapping intervals among sample years indicate significant (p < 0.05) differences. *Raw data from 1979 were unavailable but SE and 95% CI were likely similar to other sample years at the site with similar mean densities, e.g., the sample taken in 1987. This loss in mussel abundance and diversity should not be understated. For most species, especially the endangered ones, this loss represents at least a 50% decline in their population abundance throughout the river. For species that have suffered >90-95% loss in historical distribution, any additional population losses in one of their last remaining strongholds is a setback to their recovery. If the causes of decline can be identified and ameliorated, and water and habitat quality improved in this section of river, it likely will require decades for mussel populations to return to normal levels. Consequently, maintaining the healthy populations in TN is now more critical than ever. While these populations are currently large and actively recruiting, they are still vulnerable and confined to a relatively short reach of only 30-50 RKM of high quality habitat and susceptible to a catastrophic event (e.g., toxic chemical spill). These populations represent some of the last sources of individuals for stock to reestablish populations outside of the Clinch River watershed. Establishing additional populations using hatchery-propagated mussels or relocation of adult mussels from this river reach addresses 15

JONES, AHLSTEDT, OSTBY, BEATY, PINDER, ECKERT, BUTLER, HUBBS, WALKER, HANLON, SCHMERFELD, AND NEVES objectives outlined in the recovery plans for all these endangered species in pursuit of multiple recovery criteria (e.g., USFWS, 2004). Because the Ohio River valley and its numerous tributaries, including the and Cumberland rivers, are now seriously fragmented by dams, natural recolonization by mussels to remaining free-flowing rivers is not possible. Environmental management by biologists and natural resource managers, such as water quality improvements and habitat protection, and managed relocation of mussels to selected sites and rivers, is now essential to reduce risks of species extinction and promote population viability to meet the recovery goals of federally protected species. ACKNOWLEDGMENTS A special thanks is owed to the many people who volunteered to help us conduct the field work for this project: Geoff Call, Brian Evans, Matthew Patterson, and Brian Tompkins, USFWS; Joe Ferraro, Melanie Stein, and Brian Watson, Virginia Department of Game and Inland Fisheries; Richard Davis, Virginia Department of Mines, Minerals, and Energy; Amy Bush, Dan Hua, Jay McGhee, Nathan Johnson, Matt Johnson, Nick King, Missy Petty, James Vance, and Meghann Vincie, Virginia Tech University; and Chris Isaac, Travis Lowe, and Quentin Tolliver, Appalachian Technical Services. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service. LITERATURE CITED Ahlstedt, S.A., 1986. Cumberlandian Mollusk Conservation Program. Activity 1: Mussel Distribution Surveys. Final Report, Valley Authority, Office of Natural Resources and Economic Development, Knoxville,, 125 pp. Ahlstedt, S.A., 1991. 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