Mussels serve as the clean-up crew for streams and rivers. As they feed, they filter out suspended particles, organic matter, and pollutants. Large mussels can filter many gallons of water in a day.
Mussels have been living and cleaning up waterways for millions of years. More than 70 species have lived and flourished in the rivers of Southwest Virginia and east Tennessee. However, human activity through farming, allowing livestock to wallow in streams, discharging industrial and urban wastes, building roads with the subsequent runoff, harvesting timber, and mining have affected the population of mussels.
''Over the last 30 years, primarily through the research of graduate students, I have seen noteworthy changes,'' said Richard Neves, professor emeritus of fisheries and wildlife sciences within the College of Natural Resources at Virginia Tech. ''Out of at least 43 species of mussels in these rivers, 18 are now listed as federally endangered.''
Federal and state agencies, regional and local groups, individuals and businesses are working together now to clean up the rivers.
As cleanup has progressed, one of the more promising actions has been the reintroduction of mussels. With funding from several agencies, Neves has devised a method for propagating endangered species.
Neves and his students collect pregnant female mussels from the wild, remove the mussel larvae, and place them in small tanks with host fish, such as darters, logperch, and smallmouth and rock bass, so the larvae can attach to the gills. A few months later, the juveniles are of sufficient size to be placed safely in a riverbed.
Neves began the project in 1998 and by July 2000 was able to release more than 200,000 juvenile mussels of various varieties on the Tennessee side of the Clinch and Powell rivers. For the past five years, Neves' group has produced, cultured, and released more than 330,000 juvenile mussels of nine endangered species into tributaries of the Tennessee River in Virginia and Tennessee.
Meanwhile, propagation is also being done at the Virginia Department of Game and Inland Fisheries (VDGIF) Aquatic Wildlife Conservation Center. Over four years, as of summer 2007, VDGIF and the Freshwater Mussel Conservation Center at Virginia Tech produced 1.2 million individuals of 21 species.
Neves said that restoration of juveniles to the Powell River since 2003 has largely failed, but results have been better in the Clinch River.
In the Clinch/Powell River drainage, five areas with suitable water quality have been selected to augment 38 species, including 14 federal and seven state-listed endangered species. The sites are being managed by VDGIF with support from the Mussel Recovery Group, which includes personnel from VDGIF, Virginia Tech, U.S. Fish and Wildlife Service, and The Nature Conservancy.
''Strategies allow us to augment populations where they presently occur, expand populations' areas, and reintroduce where the species previously occurred,'' said Mike Pinder, VDGIF wildlife diversity project manager.
Each site is reassessed every five to six years. Larger mussels more than two to three years old are tagged individually to monitor growth and survival. ''Cultivation is an excellent strategy and larger sizes are the key,'' Pinder said. ''However, a long-term commitment is required. Some of these animals live more than 100 years.''
Richard Neves (right) pauses with Russell the Mussel, a character in Neves' 2001 children's book about mussels. Russell put in an appearance when mussels were reintroduced in the Clinch River near Cedar Bluff, Va., on property owned by The Nature Conservancy.
The mussel team released 1,000 endangered purple bean mussel juveniles. Juvenile and adult mussels of a species not endangered but had been the filtration workhorses of the Clinch River before the 1998 toxic spill that killed most aquatic life were also released. They also released adults of the fluted kidney shell mussel, which is a federal candidate for the endangered list, and adults of rabbitsfoot mussels, which are endangered.
Mussels serve as excellent indicators of water quality because of their sensitivity to particular contaminants and a typical lifespan of 20 to 50 years. Sadly, they are giving their lives to show a grim picture of water pollution. The Clinch, Powell, and Big South Fork Cumberland rivers in far Southwest Virginia and eastern Tennessee collectively contain the greatest number of endangered mussel species in North America.
From 1979 to 2007, biologists from state and federal agencies have collected quantitative data in the three rivers to document the population status and trends of more than 40 mussel species.
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