Its reclusive, silent and sedentary, but its also Mother Natures natural water filter and an indicator species to boot, and now a small group of scientists in the Southeast United States is putting in long hours in an attempt to rescue a single imperiled species of mussel.
The road back, said Dr. Jim Layzer, of the Tennessee Cooperative Fishery Research Unit, means putting a mussel back in part of its historic range and seeing it thrive, to the point where the species wont have to remain on the endangered species list.
"Recolonization is an extremely delicate process," said Layzer, who spends a lot of his time working with other researchers to find the key that will get a mussel through its first growing season. To Layzers delight, he said, "we are having great success."
Layzers efforts are aimed at reviving the population of endangered Cumberland bean (Villosa trabalis) mussels, originally found in the Tennessee and Cumberland River drainages.
Like most other mussels in trouble, these can trace some of their problems back to the early 20th century pollution played a role, and so did agriculture, logging and dams.
The plight of the freshwater mussel is neither a regional or a small problem; fully 69 species of mussels throughout the United States are already classified as threatened or endangered, and dozens more may be headed in the same direction.
A central piece of the puzzle, said Layzer who is part of an effort supported by the State of Tennessee, Tennessee Tech University, the Biological Research Division of the U.S. Geologic Survey and two U.S. Fish and Wildlife Service fish hatcheries, Dale Hollow in Tennessee and Wolf Creek in Kentucky, is how to nurturejuvenile mussels beyond the critical first 2 to 4 months.
"We need to grow them to maturity," Layzer said, "and when we can get them to that point, we can reintroduce them in quantity." Both hatcheries have encountered problems keeping young mussels alive for prolonged periods; survival after 60 days usually indicates that the mussels are meeting their nutritional requirements. Meanwhile, Layzer and his researchers have collected and reproduced wavy-rayed lampmussel, which is also found in the same river drainages as the Cumberland bean, and used them as substitutes - the lampmussel isnt endangered; if they can survive reintroduction, then there is good hope for the Cumberland bean. If the lampmussels dont survive, none of the endangered species have been lost.
"If the mussel population is in trouble, that can be a signal that other things are wrong," said Andrew Currie, who manages the Wolf Creek and Dale Hollow hatcheries.
Currie and Layzer both agree: a decline in the mussel population could not only affect water quality, they are Mother Natures natural water filters, but their absence can also indicate that something more is amiss. Mussels are capable of accumulating pesticides or heavy metals, but only to a point. Accumulated in heavy doses, those factors can then become threats to other wildlife who depend on mussels as part of their diet. That can set off a chain reaction that conceivably could even spell trouble for people who depend on parts of the rivers for drinking water.
Mussels can signal environmental changes in other ways: mussels depend on various species of fish during part of their life cycle. If dams reduce a fishs habitat, a declining fish population can also contribute to a declining mussel population.
Layzer believes that mussels are valuable simply because they are a species that are not fully understood, and because they are not fully understood, no one is able to fully appreciate their contribution.
"Were destroying or wiping out species before we know what their value might be," Layzer said. "That in itself should justify the time and expense that it takes to help them avert extinction. Beyond that, we have an ethical obligation to all the species that share this planet. When we lose anything we dont fully understand, were really losing a figurative encyclopedia. And we mightbe losing a page with enormous beneficial effects for mankind."
The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System which encompasses nearly 540 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 70 national fish hatcheries, 64 fishery resource offices and 78 ecological services field stations. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.
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For more information about the U.S. Fish and Wildlife Service, visit our home page at http://www.fws.gov
