Long-solid

In 1831, Isaac Lea described the longsolid, a medium-sized mussel, up to five inches long, which potentially live up to 50 years.  It is found in small streams to large rivers, and prefers a mixture of sand, gravel, and cobble substrates.

The mussel is found in Alabama, Kentucky, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia.  It is considered extirpated from Georgia, Indiana, and Illinois.It is currently known from three major river basins: the Ohio (where is most prevalent), Cumberland (where it is rarest), and Tennessee. It is considered extirpated from the Great Lakes basin.

It has suffered impacts from habitat fragmentation from dams and other barriers; habitat loss; degraded water quality from chemical contamination and erosion from poorly managed development, agriculture, mining, and timber operations; direct mortality from dredging and harvest; and the proliferation of invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species , such as the zebra mussel. 

We, the U.S. Fish and Wildlife Service, were petitioned by the Center for Biological Diversity (CBD), Alabama Rivers Alliance, Clinch Coalition, Dogwood Alliance, Gulf Restoration Network, Tennessee Forests Council, West Virginia Highlands Conservancy, Tierra Curry, and Noah Greenwald to list the longsolid as an endangered or threatened species under the Endangered Species Act.  This petition was part of a 2010 petition to list 404 aquatic, riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian , and wetland species in the southeastern United States.

Habitat

The longsolid shows a preference for sand and gravel in streams and small rivers, but also may be found in coarse gravel and cobble in larger rivers.  In streams and rivers they can be found at depths less than two feet, but in large rivers can be commonly found at depths of 12 to 18 feet; but also at depths of over 20 feet.

Food

Adult freshwater mussels within the longsolid’s genus filter water to eat.  Their diet consists of a mixture of algae, bacteria, detritus, and microscopic animals. 

Physical characteristics

Longsolid adults are light brown, but darken with age.  The shell is thick and medium-sized, up to five inches long, and typically has a dull sheen (Williams et al. 2008, p. 322).  Juveniles usually have a bold green ray pattern near the raised portion of the dorsal edge of the mussel shell. The shell elongates as it ages.  The foot can be orange, pale orange, or white (Schilling 2015, p. 101)

Lifecycle

There are no studies on the average life expectancy of the longsolid.  Based on aging thin sections of shells, the closely related fine-rayed pigtoe was found to live at least 32 years, and the shiny pigtoe was found to live to 20 years.  Maximum age estimates for Fusconaia as a genus are published as 51 years.  At this time, the best available information suggests that the Longsolid is a relatively long-lived species averaging 25 to 35 years, but given the large size it can attain, possibly living up to 50 years. 

The longsolid is presumed to have a complex life cycle that relies on fish hosts for successful reproduction, like other mussels. Males release sperm into the water column, which is taken in by the female where water enters the mantle cavity. The sperm fertilizes eggs that are held within the female’s gills in the marsupial chamber. The developing larvae remain in the gill chamber until they mature (called glochidia) and are ready for release in packets called conglutinates.  Following release from the female mussel, the semi-buoyant conglutinates drift in the water column where they are targeted by sight-feeding minnows. 

Specific host fishes are unknown, but based on other species of Fusconaia, likely hosts are minnows of the family Cyprinidae and genera Campostoma, Cyprinella, Notropis, and Luxilus as well as potentially sculpins of family Cottidae, genus Cottus.

The glochidia snap shut in contact with fish and attach to the gills, head, or fins of fishes.  Once on the fish, the glochidia are engulfed by tissue from the host fish that forms a cyst.  The cyst protects the glochidia and aids in their maturation.  The larvae draw nutrients from the fish and develop into juvenile mussels, weeks to months after initial attachment, then drop off the fish to continue their life on the stream bottom.

• Bruenderman, S.A., and R.J. Neves.  1993.  Life history of the endangered finerayed pigtoe, Fusconaia cuneolus (Bivalvia: Unionidae) in the Clinch River, Virginia.  American Malacological Bulletin 10(1):83–91.
• Garner, J.  2018.  Email communication between Jeff Garner, ADCNR, with Andrew Henderson, Service, regarding mussel populations in Alabama. 

• Gatenby, C.M., R.J. Neves, and B.C. Parker.  1996.  Influence of sediment and algal food on cultured juvenile freshwater mussels. Journal of the North American Benthological Society 15(4):597–609.
• Gordon, M.E., and J.B. Layzer.  1989.  Mussels (Bivalvia: Unionidea) of the Cumberland River:  Review of life histories and ecological relationships.  US Fish & Wildlife Service Biological Report 89(15).  99 pp. 
• Haag, W. 2012. North American Freshwater Mussels: Natural History, Ecology, and Conservation. Cambridge University Press, Cambridge, New York.
• Haag W.R. and A.L. Rypel.  2011.  Growth and longevity in freshwater mussels:  evolutionary and conservation implications.  Biological Reviews 86(1):225–247.
• Kitchel, H.E.  1985.  Life history of the endangered shiny pigtoe pearly mussel, Fusconia edgariana, in the North Fork Holston River, Virginia.  MS Thesis.  Virginia Polytechnic Institute and State University.  129 pp.
• Parmalee, P.W., and A.E. Bogan.  1998.  The freshwater mussels of Tennessee.  The University of Tennessee Press, Knoxville, Tennessee.  328 pp.
• Schilling, D.E.  2015.  Assessment of morphological and molecular genetic variation of freshwater mussel species belonging to the genera Fusconaia, Pleurobema, and Pleuronaia in the upper Tennessee River basin.  MS Thesis.  Virginia Polytechnic Institute and State University.  194 pp.
• Strayer, D.L., J.A. Downing, W.R. Haag, T.L. King, J.B. Layzer, T.J. Newton, and S.J. Nichols.  2004.  Changing perspectives on pearly mussels, North America’s most imperiled animals.  BioScience 54(5):429–439.
• Vaughn, C.C., and C.M. Taylor.  1999.  Impoundments and the decline of freshwater mussels: a case study of an extinction gradient.  Conservation Biology 13:912–920.
• Williams, J.D., A.E. Bogan, and J.T. Garner.  2008.  Freshwater mussels of Alabama and the Mobile Basin of Georgia, Mississippi, and Tennessee.  University of Alabama Press, Tuscaloosa.