STATUS ASSESSMENT FOR THREE IMPERILED MUSSEL SPECIES: SPECTACLECASE (CUMBERLANDIA MONODONTA), SHEEPNOSE (PLETHOBASUS CYPHYUS), AND RAYED BEAN (VILLOSA FABALIS)

Mollusk Subgroup, Ohio River Valley Ecosystem Team

Abstract

The Ohio River Valley Ecosystem Team, Mollusk Subgroup, conducted a cursory review of the status of 19 imperiled wide-ranging mussels centered in the Ohio River system. We surmised that status assessments for these species would be problematic for individual U.S. Fish and Wildlife Service field offices to conduct given their broad ranges. Detailed status assessments were undertaken for the spectaclecase (Cumberlandia monodonta), sheepnose (Plethobasus cyphyus), and the rayed bean (Villosa fabalis). The spectaclecase and sheepnose are large river species known from the upper portions of the Mississippi River system, while the rayed bean is a smaller stream species known from the Ohio River and middle Great Lakes drainages. Historically known from 45 streams, the spectaclecase is currently extant in 20 streams. Six of the 20 streams with extant spectaclecase populations are represented by single recent specimens, while viable populations occur in 8 streams. Currently, the sheepnose is known from 26 of the 79 streams where it historically occurred, and is thought to be viable in over half of the streams with extant populations. The rayed bean was historically known from 109 streams, lakes, and canals, but the species is now found in only 22 streams and a single lake. Viable rayed bean populations occur in nine streams. Habitat alterations (e.g., impoundments, channelization, mining, pollutants, sedimentation) and the introduced zebra mussel (Dreissena polymorpha) are thought to have contributed to their collective imperilment. Based on these data, the Mollusk Subgroup recommends that the spectaclecase, sheepnose, and rayed bean be considered for elevation to candidate status under the Endangered Species Act.

Introduction

•  The native freshwater mussels (families Margaritiferidae and Unionidae) of North America are the continent’s most imperiled major faunal group.

• Over two-thirds of the approximately 300 recognized taxa are considered jeopardized (Williams et al. 1993), with only 70 taxa currently protected under the Endangered Species Act.
  
• The conservation strategies needed to conduct recovery actions for mussels have been formalized (National Native Mussel Conservation Committee 1998).

• The Mollusk Subgroup of the U.S. Fish and Wildlife Service (FWS) Ohio River Valley Ecosystem (ORVE) Team has met annually for almost 10 years--pre-dating the actual ecosystem team--to discuss conservation issues for aquatic mollusks.
  
• The Subgroup has representatives from more than 15 Federal and State agencies, non-governmental organizations, and consulting firms from throughout the eastern US.

• In November, 2000, the Subgroup discussed the general status of 19 wide- ranging imperiled taxa that were potentially "falling through the cracks" of conservation.

• Their wide ranges make it difficult for any one field office to adequately address rangewide imperilment, but given the Subgroup’s level of expertise, an excellent role for us was to conduct rangewide status reviews.
  
• We decided upon three taxa, spectaclecase (Cumberlandia monodonta), sheepnose (Plethobasus cyphyus), and rayed bean (Villosa fabalis), to focus initial efforts.
  
• These three species were deemed in the greatest need of protection and adequate information was available to readily determine their status.
  
• Information on the biology, distribution, threats, and current status was compiled as comprehensive status reviews for these taxa (Ohio River Valley Ecosystem Team Mollusk Subgroup 2003a, b, c).
  
• Currently, lead field offices in the FWS’s Midwestern Region (Region 3) are seeking candidate status for Federal listing for the spectaclecase, sheepnose, and rayed bean.

Methods and Materials

• Information on the biology, distribution, threats, and current status of the spectaclecase, sheepnose, and rayed bean has been gathered from a large body of published and unpublished survey work conducted rangewide since the 1800s.
  
• More current, unpublished distribution and status information has been obtained from biologists with State Heritage Programs, governmental agencies, academia, museums, and others.
  
• Museum records represented the following institutions: The Academy of Natural Sciences of Philadelphia, American Museum of Natural History, Carnegie Museum, Chicago Academy of Science, Field Museum of Natural History, Florida Museum of Natural History, Illinois Natural History Survey, Illinois State Museum, Indiana State Museum, J.F. Bell Museum of Natural History, Los Angeles County Museum, Marshall University Mollusk Collection, Museum of Comparative Zoology, Museum of Fluviatile Mollusks, Ohio State University Museum of Biological Diversity, Royal Ontario Museum, University of Massachusetts Museum of Invertebrate Zoology (Mollusks), University of Michigan Museum of Zoology, and U.S. National Museum.
  
• Figures 1, 2, and 3 were created in ESRI ArcView GIS 3.3 and depict the distribution of the spectaclecase, sheepnose, and rayed bean, respectively. Species occurrences are presented at the county level.
  
• The bar graph in Figure 4 was created using Microsoft Excel and depicts the number of historical vs. extant streams of occurrence for the three species.
  
• The poster was plotted and printed on an HP 3500CP.
  
• Status information presented herein is detailed in three status reviews (Ohio River Valley Ecosystem Team Mollusk Subgroup 2003a, b, c).

 

General Biology and Habitat

The following information is generally summarized from Oesch (1984), Parmalee and Bogan (1998), and others.

General Information on Mussels

• Lotic mussels occur chiefly in flow refuges, or relatively stable areas that display little movement of particles during flood events (Strayer 1999a).
  
• These suspension feeders are relatively immobile and long-lived.

• Most species have separate sexes, internal fertilization, and specialized larvae (glochidia) that require specific hosts (generally fishes) in order for their survival to be ensured.
  
• Newly-metamorphosed juveniles drop off hosts to begin a free-living existence on the stream bottom, but must drop off in suitable habitat for survival.
  
• The complex life history of mussels has many weak links that may prevent successful reproduction and recruitment of juveniles into existing populations.

 

Biological Information Specific to the Three Species

Cumberlandia monodonta

• The spectaclecase (family Margaritiferidae) is a large mussel that reaches at least 9.25 inches in length, with a greatly elongated shell.
  
• The spectaclecase is more of a habitat specialist than are most mussel species.
  
• Primarily a large-river species, it often inhabits riverine microhabitats sheltered from the main force of current, oftentimes under slab boulders or bedrock shelves.
  
• Spectaclecase occurrences tend to be aggregated.
  
• Baird (2000) completed a life history of this species in the Meramec and Gasconade Rivers (MO) making it one of the best known large river species.
  
• Age at sexual maturity has been estimated at 4-5 years for males and 5-7 years for females.
  
• Their glochidia are the smallest known for any North American mussel.
  
• All four gills are used as a marsupium for their glochidia.
  
• The conglutinates of the spectaclecase are flat and white, and some may be forked, but are highly variable in size.
  
• The number of conglutinates per individual averaged 64.5 with tens to hundreds of thousands of the hookless glochidia occuring in each conglutinate.
  
• Total fecundity (including glochidia and ova) varies from 1.93-9.57 million per female.
  
• Despite our knowledge of the species’ life history, its’ host(s) remains unknown.

Plethobasus cyphyus

• The sheepnose (family Unionidae) is a medium-sized mussel that reaches nearly 5.5 inches in length.
  
• It is primarily a larger-stream species occurring in shoal habitats with moderate to swift currents over coarse sand and gravel, but also in mud, cobble, and boulders.
  
• The outer pair of gills is used as a marsupium.
  
• Glochidia are released in the form of pink conglutinates, which mimic small worms (Ortmann 1911).
  
• The sauger (Stizostedion canadense) is the only known natural host (Surber 1913), but others are likely suitable.

Villosa fabalis

• The rayed bean (family Unionidae) is a small mussel usually less than 1.8 inches in length.
  
• It is generally found in headwater streams in shoal or riffle areas, and in wave-washed areas of glacial lakes in gravel and sand, and is oftentimes associated with vegetation.
  
• They utilize a discreet portion of the outer pair of gills as a marsupium.
  
• Observations suggest that females have numerous papillae arranged along the mantle edge, which "zip" rhythmically and "quiver" when displaying (J.W. Jones, VPI & SU, pers. comm., 2002).
  
• Glochidia are released in mass when the lure is stimulated.
  
• The Tippecanoe darter (Etheostoma tippecanoe) has been identified as a host fish for the rayed bean (White et al. 1996), but other species are surely utilized because the ranges of the two species are not congruent.
  
• Potential hosts include several species of darter, sculpin, and largemouth bass (Micropterus salmoides) (Woolnough 2002; J.W. Jones, VPI & SU, pers. comm., 2002).

Distribution and Current Status of Cumberlandia monodonta

Historically, the spectaclecase occurred throughout much of the Mississippi River system (with the exception of the upper Missouri River system), the lower two-thirds of the Ohio River system, the Cumberland and Tennessee River systems, and some tributaries of the lower Mississippi River in Arkansas. The spectaclecase was historically known from 45 streams in 15 states and 4 FWS regions--3 (Midwest), 4 (Southeast), 5 (Northeast), and 6 (Great Plains). Currently, it is known from 20 streams (in bold below). Extant populations thought to be recruiting and exhibiting some level of population viability are in bold italics. These include by stream system (with tributaries) the following:

Upper Mississippi River system

Mississippi River; St. Croix River (Rush Creek), Chippewa River, Rock River, Salt River, Illinois River (Des Plaines River, Kankakee River), Meramec River (Bourbeuse River, Big River), Kaskaskia River, Joachim Creek

Lower Missouri River system

Missouri River; Platte River, River Aux Vases, Osage River (Sac River, Marais des Cygnes River), Gasconade River (Osage Fork, Big Piney River)

Ohio River system

Ohio River; Muskingum River, Kanawha River, Green River, Wabash River

Cumberland River system

Cumberland River; Big South Fork, Caney Fork, Stones River, Red River

Tennessee River system

Tennessee River; Holston River, Nolichucky River, Little River, Little Tennessee River, Clinch River (Powell River), Sequatchie River, Elk River, Duck River

Lower Mississippi River system

Mulberry River, Ouachita River

Summary

•  Twenty streams are thought to harbor extant populations of the spectaclecase, a 55% decrease in the total number of streams from which it was historically known.
  
•  The St. Croix (MN & WI), Meramec (MO), Gasconade (MO), and Clinch (TN & VA) Rivers represent the largest viable populations remaining.
  
• Six of the 20 streams are recently represented by single live specimens (i.e., Chippewa, Ohio, Kanawha, Duck, Mulberry Rivers; Caney Fork).
  
• The spectaclecase has nearly disappeared from the entire Ohio River system non-inclusive of the Cumberland and Tennessee River systems.
  
• Historically known from 15 states (AL, AR, IL, IN, IA, KS, KY, MN, MO, NE, OH, TN, VA, WV, and WI), the spectaclecase is considered extirpated from IN, KS, NE, and OH.

Distribution and Current Status of Plethobasus cyphyus

Historically, the sheepnose occurred throughout much of the Mississippi River system with the exception of the upper Missouri River system and most lowland tributaries in the lower Mississippi River system. The sheepnose was historically known from 79 streams (including 1 canal) in 15 states and 3 FWS regions--3 (Midwest), 4 (Southeast), and 5 (Northeast). Currently, it is known from 26 streams (in bold below). Extant populations thought to be recruiting and exhibiting some level of population viability are in bold italics. These include by stream system (with tributaries) the following:

Upper Mississippi River system

Mississippi River; Minnesota River, St. Croix River, Chippewa River (Flambeau River), Wisconsin River, Rock River, Iowa River, Skunk River, Des Moines River, Illinois River (Des Plaines River, Kankakee River, Fox River, Mackinaw River, Spoon River, Sangamon River [Salt Creek], Quiver Creek, Illinois and Michigan Canal), Meramec River (Bourbeuse River, Big River), Kaskaskia River, Saline River, Castor River, Whitewater River

Lower Missouri River system

Little Sioux River, Little Blue River, Gasconade River (Osage Fork)

Ohio River system

Ohio River; Allegheny River (Hemlock Creek), Monongahela River, Beaver River (Duck Creek), Muskingum River (Tuscarawas River, Walhonding River [Mohican River], Otter Fork Licking River), Kanawha River, Scioto River, Little Miami River, Licking River, Kentucky River, Salt River, Green River (Barren River), Wabash River (Mississinewa River, Eel River, Tippecanoe River, Vermillion River, Embarras River, White River [East Fork White River, West Fork White River])

Cumberland River system

Cumberland River; Obey River, Caney Fork, Harpeth River

Tennessee River system

Tennessee River; Holston River (North Fork Holston River), French Broad River (Little Pigeon River), Little Tennessee River, Clinch River (North Fork Clinch River, Powell River), Hiwassee River, Duck River)

Lower Mississippi River system

Hatchie River, Black River, Yazoo River (Big Sunflower River), Big Black River

Summary

• Twenty-six streams are thought to harbor extant sheepnose populations, a decrease of two-thirds in the total number of streams from which it was historically known.
  
• The Chippewa/Flambeau (WI), Meramec (MO), Green (KY), and Clinch (TN & VA) Rivers have some of the best viable populations remaining.
  
• Although probably harboring the largest population rangewide, the population in the Holston River (TN) has not recruited in decades and is slowly dying out.
  
• As many as 15 streams may have viable populations of the sheepnose, but population sizes are generally small.
  
• The sheepnose was historically known from 14 states (AL, IL, IN, IA, KY, MN, MS, MO, OH, PA, TN, VA, WV, and WI), and is still extant in all of them.

Distribution and Current Status of Villosa fabalis

Historically, the rayed bean occurred in parts of the upper Great Lakes system (i.e., Lake Michigan drainage), lower Great Lakes system, and throughout most of the Ohio and Tennessee River systems, but absent from the Cumberland River system. The rayed bean was historically known from 109 streams, lakes, and some man-made canals in 11 states and 3 FWS regions--3 (Midwest), 4 (Southeast), and 5 (Northeast). Currently, it is known from 22 streams and a lake (in bold below). Extant populations thought to be recruiting and exhibiting some level of population viability are in bold italics. These include by stream system (with tributaries) the following:

Upper Great Lakes system

Pigeon River

Lower Great Lakes system

Black River (Mill Creek), Pine River, Belle River, Clinton River (North Fork Clinton River), Sydenham River, South Branch Thames River, Detroit River, Rouge River, Huron River, Raisin River (Macon Creek), Maumee River (St. Joseph River [West Branch St. Joseph River, Fish Creek, Cedar Creek, Feeder Canal to St. Joseph River], Auglaize River [Ottawa River, Blanchard River]), Sandusky River (Tymochtee Creek, Wolf Creek), Lake Erie

Ohio River system

Ohio River; Allegheny River (Chautauqua Lake outlet; Chautauqua Lake; Olean Creek, Cassadaga Creek, Conewango Creek, Oil Creek, French Creek [Cussewago Creek], Crooked Creek), West Fork River, Beaver River (Shenango River, Mahoning River, Pymatuning Creek), Middle Island Creek; Muskingum River (Tuscarawas River, Walhonding River, Mohican River), Elk River, Scioto River (Olentangy River, Mill Creek, Alum Creek, Blacklick Creek, Whetstone Creek, Big Walnut Creek [Walnut Creek], Big Darby Creek [Little Darby Creek], Deer Creek, Sugar Creek, Scioto Brush Creek, Cedar Creek, Buckeye Lake, Ohio and Erie Canal), Little Miami River (East Fork Little Miami River), Stillwater River, South Fork Licking River, North Fork Elkhorn Creek, Eagle Creek, Brashears Creek, Green River (Nolin River, Barren River), Wabash River (Salamonie River, Mississinewa River, Tippecanoe River [Tippecanoe Lake, Winona Lake, Lake Maxinkuckee], Vermilion River [Salt Fork Vermilion River, Middle Fork Vermilion River, North Fork Vermilion River], Embarras River, Sugar Creek, White River [East Fork White River (Big Blue River, Walnut Creek, Mill Creek, Fall Creek, Sugar Creeks)], West Fork White River)

Tennessee River system

Tennessee River; Holston River, (North Fork Holston River, South Fork Holston River), Nolichucky River (Lick Creek), First Creek, Clinch River (North Fork Clinch River, Powell River), Elk River (Richland Creek), Duck River

Summary

• Twenty-two streams and a lake are thought to harbor extant populations of the rayed bean, indicating that it has been eliminated from 78% of its streams and lakes of historical occurrence.
  
• The Sydenham (ONT), Blanchard (OH), and Allegheny (PA) Rivers; and French Creek (PA) appear to have the largest, best viable populations remaining
  
• Several other smaller, but considered viable, populations occur in isolated and generally short stream reaches (e.g., Tippecanoe River, IN; Pine, Clinton Rivers, MI; Cassadaga, Olean Creeks, NY).
  
• Lake Maxinkuckee, the only non-stream population remaining, is a glacial lake in the headwaters of the Tippecanoe River.
  
• Paradoxically, this species was never recorded from the Cumberland River system.
  
• Historically known from 11 states (AL, IL, IN, KY, MI, NY, OH, PA, TN, VA, and WV) and a Canadian province (ONT), the rayed bean has disappeared from six states (AL, IL, KY, TN, VA, WV) and is considered extirpated from all streams south of the Ohio River.

General Threats

The decline of the spectaclecase, sheepnose, rayed bean, and scores of other mussel species in North America is primarily the result of habitat loss and degradation. These losses have been well documented since the mid-19th century. General categories of these threats include impoundments, channelization, chemical contaminants, mining, sedimentation and alien species (Williams et al. 1993, Neves 1993, Neves et al. 1997, Watters 2000). Bryan and Rutherford (1993) provide a comprehensive overview of habitat alterations affecting warmwater streams. The indirect impacts from population fragmentation and genetic considerations are also discussed. Exploitation has been heralded as a significant threat to mussels (e.g., Anthony and Downing 2001). However, exploitation has resulted in localized population declines of mussels, but has not represented a root cause in the critical imperilment or extinction of any species. Bourgeoning human populations will invariably increase the likelihood that many if not all of the threat factors in this section will continue to impact mussel populations. Following is a summary of this information.

Impoundments

• Neves et al. (1997) and Watters (2000) reviewed effects of impoundments on mussels.
  
• Impoundments result in the dramatic modification of riffle and shoal habitats.
  
• They interrupt most of a river's ecological processes.
  
• Dams also seriously alter downstream water quality, thermal regimes, and riverine habitat.
  
• Dams can affect the distribution of host fishes that can then affect distribution and reproduction of mussels.

Channelization

• Hartfield (1993), Neves et al. (1997), and Watters (2000) reviewed the specific effects of channelization on mussels.
  
• Channelization impacts a stream’s physical, ecological, and biological characteristics.
  
• Actively maintained navigation channels are prevalent in the range of these three species.

Chemical Contaminants

• The effects of chemical contaminants on freshwater mussels were reviewed by Havlik and Marking (1987), Naimo (1995), Keller and Lydy (1997), and Neves et al. (1997).
  
• Contaminants can degrade water and substrate quality and adversely impact mussel populations.
  
• Mussels are very intolerant of heavy metals (e.g., cadmium, chromium, copper, mercury, zinc), other substances (e.g., ammonia, chlorine, pesticides), and excessive nutrification.
  
• The effects of contaminants are especially profound on juvenile mussels, which can readily ingest contaminants adsorbed to sediment particles while pedal feeding.

Mining

• Mining for various minerals and fossil fuels (e.g., coal, oil, gas, in-stream aggregate) have impacted mussel populations in many streams.
  
• Kitchel et al. (1981) reviewed the effects of coal mining, a major threat to mussels.
  
• Mining activities produce sedimentation and heavy metal-rich runoff, brine, and organic pollutants.
  
• Instream sand and gravel mining results in changes in stream channels, water quality, and macroinvertebrate and fish populations (Kanehl and Lyons 1992, Roell 1999).

Sedimentation

• Sources, biological effects, and sediment control were reviewed by Waters (1995), while Marking and Bills (1979) and Brim Box and Mossa (1999) reviewed specific impacts to mussels.
  
• g Specific biological impacts on mussels include reduced feeding and respiratory efficiency, disrupted metabolic processes, reduced growth rates, limited burrowing activity, and physical smothering.
  
• g Interstitial spaces, crucial habitat for juveniles, are clogged by sediments thus reducing recruitment rates.
  
• Sediment may act as a vector for delivering contaminants to streams, and contribute to direct early juvenile mortality during normal pedal feeding activities.

Alien Species

• Chief among these are the zebra mussel (Dreissena polymorpha) and secondarily, the Asian clam (Corbicula fluminea).
  
• Zebra mussel impacts include impeding locomotion, interfering with normal valve movements, depleting food resources, increasing waste products, degrading mussel habitat, and potentially filtering mussel sperm and glochidia (Strayer 1999b).
  
• Asian clam impacts include impacting the survival and growth of newly metamorphosed juvenile mussels, ingesting glochidia, reducing growth rates, and displacing juvenile mussels downstream (Yeager et al. 2001).
  
• Periodic die-offs of these invaders may produce enough ammonia and consume enough oxygen to kill native mussels (Strayer 1999b).
  
• A potential alien threat is the black carp (Mylopharyngodon piceus), an eastern Asian molluscivore which has been introduced to control snail (a vector for parasites) populations in commercial fish ponds.

Indirect Impacts

• Population fragmentation and isolation makes extant populations much more susceptible to extirpation from single catastrophic events (e.g., toxic chemical spills).
  
• Population isolation makes repopulation impossible without human intervention and prevents the natural interchange of genetic material between populations.
  
• Genetic considerations include reducing the reservoir of genetic diversity within populations potentially leading to inbreeding depression (Avise and Hambrick 1996).
  
• Small isolated populations increase the likelihood that the effective population size required to maintain long-term population viability is not attained (Soulé 1980).
  
• Recruitment reduction or failure becomes much more likely in small isolated populations.

 

Conservation Recommendations

The following actions are among those needed to preserve and recover these species.

Surveys to search for additional occurrences.

• Extant populations need to be protected and threats to these populations reduced or eliminated.
  
• Propagation technology should be developed to facilitate population augmentation and reintroduction into historical habitat.
  
• Programs should be established in streams with extant populations to monitor their status, document changes in imminency and magnitude of threats, etc.
  
• The effective population size needed for long-term population viability is crucial information for recovery.
  
• Partnering is needed with a wide range of stakeholders to protect extant populations, effect riparian restoration and the establishment of buffers, leverage conservation project dollars, expand environmental outreach efforts, etc.
  
• Monitoring plans should be implemented for the presence and potential expansion of alien species, such as the zebra mussel.
  
• Other research needed includes determining the effects of common contaminants on all life stages, developing criteria indicative of healthy viable populations, generating better life history information (e.g., hosts for the spectaclecase), producing habitat suitability criteria for translocation efforts, performing taxonomic distinctiveness studies rangewide, etc.

Acknowledgments

We wish to thank the following for providing data for the status reviews: Steve Ahlstedt, Jim Layzer, Dick Neves, Jeff Powell, and Rita Villella (USGS); Bob Anderson, Bob Butler, Patty Morrison, Andy Roberts, Susan Rogers, Bill Tolin, Rob Tawes, and Jim Widlak (FWS); Herb Athearn (Museum of Fluviatile Mollusks); Peter Badra (Michigan Natural Features Inventory); Terry Balding (Univ. of Wisconsin-Eau Claire); Chris Barnhart (Southwest Missouri State Univ.); Dick Biggins (retired USFWS); Sue Bruenderman (Missouri Dept. of Conservation); Stuart Butler (father of ORVE Mollusk Subgroup leader); Ron Cicerello (Kentucky State Nature Preserves Commission); Mark Clapsadl (Chautauqua Erie Environmental Center); Janet Clayton (West Virginia Division of Natural Resources); Kevin Cummings (Illinois Natural History Survey); Mike Davis and Bernard Sietman (Minnesota Dept. of Natural Resources); Heidi Dunn (Ecological Specialists, Inc.); Brant Fisher (Indiana Dept. of Natural Resources); Steve Fraley (North Carolina Wildlife Resources Commission); Jeff Garner (Alabama Dept. of Conservation and Natural Resources); Dan Graf (The Academy of Natural Sciences of Philadelphia); John Harris (Arkansas Highway and Transportation Dept.); Marian Havlik (Malacological Consultants, Inc.); David Heath and Lisie Kitchel (Wisconsin Dept. of Natural Resources); Mike Hoggarth (Otterbein College); Mark Hove (Univ. of Minnesota); Don Hubbs (Tennessee Wildlife Resources Agency); Doug Johnson (Miami Conservancy District); Bob Jones (Mississippi Museum of Natural Science); Jess Jones (Virginia Polytechnic Institute and State Univ.); Dan Kelner (U.S. Army Corps of Engineers); Janice Smith-Metcalfe (Environment Canada); Brian Obermeyer (Stream & Prairie Research); Kathy O’Brien (New York State Dept. of Environmental Conservation); Tom Proch (Pennsylvania Dept. of Environmental Protection); Randy Sanders (Ohio Dept. of Natural Resources); Peggy Shute (TVA); Doug Smith (Univ. of Massachusetts); Dave Strayer (Institute of Ecosystem Studies); Tom Watters (Ohio State Univ.); Daelyn Woolnough (Iowa State Univ.); and Greg Zimmerman (EnviroScience, Inc.). The following members of the ORVE Mollusk Subgroup assisted with the preparation of this poster: Steve Ahlstedt, Bob Butler, Kevin Cummings, Heidi Dunn, Brant Fisher, Ryan Evans (Western Pennsylvania Conservancy); Patty Morrison, Kurt Snider (FWS), Rita Villella, Tom Watters, Jim Widlak, and Greg Zimmerman. Special thanks go to FWS Region 3 biologists Angela Boyer, Phil Delphey, Jody Millar, T.J. Miller, Sarena Selbo, and Leslie Tewinkel for their hard work in pursuing candidate elevation for the spectaclecase, sheepnose, and rayed bean.

Literature Cited

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(10):2071-2090.

Avise, J.C., and J.L. Hambrick, eds. 1996. Conservation genetics: case histories from nature. Chapman and Hall, New York.

Baird, M.S. 2000. Life history of the spectaclecase, Cumberlandia monodonta Say, 1829 (Bivalvia, Unionoidea, Margaritiferidae). Unpublished master’s thesis, Southwest Missouri State University, Springfield. 108 pp.

Brim Box, J., and J. Mossa. 1999. Sediment, land use, and freshwater mussels: prospects and problems. Journal of the North American Benthological Society 18(1):99_117.

Bryan, C.F., and D.A. Rutherford, eds. 1993. Impacts on warmwater streams: guidelines for evaluation. Southern Division, American Fisheries Society, Little Rock, Arkansas.

Hartfield, P.W. 1993. Headcuts and their effect on freshwater mussels. Pp. 131_141 in: K.S. Cummings, A.C. Buchanan, and L.M. Koch, eds. Conservation and Management of Freshwater Mussels. Proceedings of a UMRCC Symposium, October 1992, St. Louis, Missouri. Upper Mississippi River Conservation Committee, Rock Island, Illinois.

Havlik, M.E., and L.L. Marking. 1987. Effects of contaminants on naiad mollusks (Unionidae): a review. U.S. Fish and Wildlife Service Resource Publication 164. 20 pp.

Kanehl, P., and J. Lyons. 1992. Impacts of in-stream sand and gravel mining on stream habitat and fish communities, including a survey on the Big Rib River, Marathon County, Wisconsin. Wisconsin Department of Natural Resources Research Report 155. 32 pp.

Keller, A.E., and M. Lydy. 1997. Biomonitoring and the hazards of contaminants to freshwater mollusks. Unpublished report in: Freshwater mollusks as indicators of water quality: a workshop. U.S. Geological Survey Biological Resources Division and National Water Quality Assessment Program. 55 pp.

Kitchel, H.E., J.C. Widlak, and R.J. Neves. 1981. The impact of coal-mining waste on endangered mussel populations in the Powell River, Lee County, Virginia. Unpublished Report to the Virginia State Water Control Board, Richmond. 26 pp.

Marking, L.L., and T.D. Bills. 1979. Acute effects of silt and sand sedimentation on freshwater mussels. Pp. 204_211 in: J.R. Rasmussen, ed. Proceedings of the UMRCC symposium on Upper Mississippi River bivalve mollusks. Upper Mississippi River Conservation Committee, Rock Island, Illinois.

Naimo, T.J. 1995. A review of the effects of heavy metals on freshwater mussels. Ecotoxicology 4:341_362.

National Native Mussel Conservation Committee. 1998. National strategy for the conservation of native freshwater mussels. Journal of Shellfish Research 17(5):1419_1428.

Neves, R.J. 1993. A state-of-the unionid address. Pp. 1-10 in: K.S. Cummings, A.C. Buchanan, and L.M. Koch, eds. Conservation and management of freshwater mussels. Proceedings of a UMRCC symposium, October 1992, St. Louis, Missouri. Upper Mississippi River Conservation Committee, Rock Island, Illinois.

Neves, R.J., A.E. Bogan, J.D. Williams, S.A. Ahlstedt, and P.W. Hartfield. 1997. Status of aquatic mollusks in the southeastern United States: a downward spiral of diversity. Pp. 43-85 in: G.W. Benz and D.E. Collins, eds. Aquatic fauna in peril: the southeastern perspective, March-April 1994, Chattanooga, Tennessee. Special Publication 1, Southeast Aquatic Research Institute, Chattanooga.

Ohio River Valley Ecosystem Team Mollusk Subgroup. 2003a. Status assessment for the spectaclecase, Cumberlandia monodonta, occurring in the Mississippi River system. Unpublished report, U.S. Fish and Wildlife Service, Asheville, North Carolina. 67 pp.

Ohio River Valley Ecosystem Team Mollusk Subgroup. 2003b. Status assessment for the sheepnose, Plethobasus cyphyus, occurring in the Mississippi River system. Unpublished report, U.S. Fish and Wildlife Service, Asheville, North Carolina. 84 pp.

Ohio River Valley Ecosystem Team Mollusk Subgroup. 2003c. Status assessment for the rayed bean, Villosa fabalis, occurring in the Mississippi River and Great Lakes systems. Unpublished report, U.S. Fish and Wildlife Service, Asheville, North Carolina. 65 pp.

Oesch, R.D. 1984. Missouri naiades: a guide to the mussels of Missouri. Missouri Department of Conservation, Jefferson City. 270 pp.

Ortmann, A.E. 1911. A monograph of the naiades of Pennsylvania. Parts I and II: systematic account of the genera and species. Memoirs of the Carnegie Museum 4(6):279-347.

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

Roell, M.J. 1999. Sand and gravel mining in Missouri stream systems: aquatic resources effects and management alternatives. Unpublished report, Missouri Department of Conservation, Columbia. 34 pp.

Soulé, M.E. 1980. Threshold for survival: maintaining fitness and evolutionary potential. Pp. 151-169 in: M.E. Soulé and B.A. Wilcox, eds. Conservation biology. Sinauer Associates, Inc., Sunderland, Massachusetts.

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. 1999b. Effects of alien species on freshwater mollusks in North America. Journal of the North American Benthological Society 18(1):74-98.

Surber, T. 1913. Notes on the natural hosts of fresh-water mussels. Bulletin of U. S. Bureau of Fisheries 32:101-115.

Waters, T.F. 1995. Sediment in streams: sources, biological effects, and control. American Fisheries Society Monograph 7. 251 pp.

Watters, G.T. 2000. Freshwater mollusks and water quality: effects of hydrologic and instream habitat alterations. Pp. 261-274 in: P.D. Johnson and R.S. Butler, eds. Freshwater Mollusk Symposium Proceedings__Part II: Proceedings of the First Symposium of the Freshwater Mollusk Conservation Society, March 1999, Chattanooga, Tennessee. Ohio Biological Survey, Columbus.

White, L.R., B.A. McPheron, and J.R. Stauffer. 1996. Molecular genetic identification tools for the unionids of French Creek, Pennsylvania. Malacologia 33:181-202.

Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993. Conservation status of freshwater mussels of the United States and Canada. Fisheries 18(9):6_22.

Woolnough, D.A. 2002. Life history of endangered freshwater mussels of the Sydenham River, southwestern Ontario, Canada. Unpublished master’s thesis, University of Guelph, Guelph, Ontario.

Yeager, M.M., R.J. Neves, and D.S. Cherry. 2001. Competitive interactions between early life stages of Villosa iris (Bivalvia: Unionidae) and adult Asian clams (Corbicula fluminea). Pp. 252-259 in: P.D. Johnson and R.S. Butler, eds. Freshwater Mollusk Symposium Proceedings__Part II: Proceedings of the First Symposium of the Freshwater Mollusk Conservation Society, March 1999, Chattanooga, Tennessee. Ohio Biological Survey, Columbus.