Mussel populations studied in Virginia

Clinch River features one of world's most diverse arrays of the mollusks

August 28, 2002|By Rex Springston and Bill Godsil | Rex Springston and Bill Godsil,RICHMOND TIMES-DISPATCH

CLEVELAND, Va. - Snorkeling in the cool Clinch River, biologist Fred Huber pointed to an unusual creature resting on the bottom, a wavy-rayed lampmussel.

The silver-dollar-size mollusk flaunted a thin, fleshy flap that extended from inside its shell. The flap resembled a minnow in its color, shape and fluttering motion.

Huber pointed just inside the flap where baby mussels clung, ready to leave their mother.

Hitching a ride

Popping his head above water, Huber explained that baby mussels live part of their lives on the gills of fish. That enables the mollusks, which don't move far in adulthood, to hitch rides up and down rivers to claim more territory.

If a hungry small-mouth bass swam up to nibble the bogus minnow, the mother mussel would release the babies onto the bass. The bass would become the babies' unwitting keeper for about two weeks, when the young mussels would drop to the river's bottom.

"I think that's really cool," Huber said. "The evolution is incredible."

The object of Huber's affection is one of about 45 mussel species found in the Clinch River in far southwest Virginia. The Clinch features one of the most ancient and diverse arrays of freshwater mussels in the world.

Mussels have suffered in recent decades. Pollution, dams, poor farming practices and other threats killed many of the mollusks. Many live on the brink of extinction.

Huber, of the U.S. Forest Service, was part of a team of federal, state and nonprofit scientists who recently snorkeled a stretch of the Clinch in Russell County to map the mussels there. The effort was part of a larger program to rebuild southwest Virginia's mussel populations with young ones raised in captivity.

Why care about mussels? The creatures need clean water in which to live. At the same time, they cleanse rivers of bacteria and other impurities.

"The mussels' health is basically an indicator of the river's health," said Braven Beaty, a stewardship ecologist for the Nature Conservancy, an environmental group helping to protect the Clinch.

If people want clean rivers to swim and fish in, Beaty said, they should strive to preserve an environment in which mussels flourish.

Mollusks are resistant to tumors, so mussels could prove important to cancer research, said Dr. Richard J. Neves, a federal mussel expert based at Virginia Tech.

"If they are gone, we will never be able to find out," he said.

Mussels also are important ecologically, providing food for muskrats, raccoons and other animals.

By building mussels in southwest Virginia, the state can take a strong step toward making rivers there whole again, said Raymond T. Fernald, manager of the state Department of Game and Inland Fisheries' nongame program.

Mussels also are part of the region's lore. The rare ones include the colorfully named snuffbox, Tennessee pigtoe, purple liliput and pink heelsplitter. The heelsplitter's shell features a jagged point that some unlucky mountaineer surely discovered the hard way.

Depending on the species, mussels can be as small as nickels or as big as saucers. They are variously tan, straw yellow, brown, dark green or black. Some feature starburst lines radiating from a central point; some are marked with chevrons.

Used for buttons

The insides of their shells are lined with an iridescent mother- of-pearl that can be blue, purple, white or pink. Mussels were collected by the ton to make buttons before plastic became king in the 20th century.

The upper reaches of the Tennessee River basin - the Clinch, Holston and Powell rivers - are renowned havens for rare mussels.

The rivers are millions of years old. They escaped Ice Age glaciers and rising sea levels that periodically infused rivers to the east with saltwater.

That gave creatures in that region a long time to evolve, resulting in populations of unusual mussels and fish. Of the region's roughly 50 species of mussels, 32 are so rare that they are considered endangered or threatened.

The Clinch is a good place to try to rebuild mussel populations because it has not been dammed and has no major industries along it, Neves said. "It stands out because it hasn't been degraded like most of these other river systems."

Last month, Neves, Huber and the other scientists donned masks and snorkels and scoured the river's bottom to determine the numbers and types of mussels there.

The scientists found 22 mussel species, several of them rare. Later this summer, state game officials plan to release young, hatchery-raised mussels at the site. Those will include wavy-rayed lampmussels and rainbow mussels, species that are uncommon in that area.

In a few years, scientists will return to the Clinch and count mussels again. They will compare those numbers with the data collected this year. That will show how the youngsters are doing. And it will answer the question: Do the releases help mussel populations grow?

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