A national recreation area popular with boaters, hikers, and equestrians, the riverway contains 90 free-flowing miles (145 kilometers) of the Big South Fork of the Cumberland River. The river system harbors more federally listed aquatic species, including mussels, than any other U.S. national park.
In recent decades, however, mussels there have fallen prone to numerous upstream threats. Mining, logging, oil and gas drilling, among other activities, have sent pollutants into the waterway and the reserve's sensitive mussel breeding sites.
The mussel baby-making project is designed to tip the scales in favor of the fragile species.
Mussels depend on certain fish that host the mollusks for part of their reproductive cycle. The delicate process is complicated to replicate in a laboratory.
Hatchery staff first take egg-bearing female mussels from the river and place them in holding tanks. The biologists then take fertilized mussel eggs and place them on the gills of fish hosts, where they develop into juvenile mussels.
Once the juveniles drop off their hosts and reach a viable size, they are returned to the river system. The goal is to spread mussel populations throughout the park so that individual species are not so vulnerable.
"A lot of what we're doing is very new," said Jess Jones, a U.S. Fish and Wildlife Service biologist who works with the Virginia Tech hatchery. "We're just scratching the surface of this process. We don't really know yet how many individuals we have to reintroduce to bump up an endangered species. The more we learn, the more we realize we need to do."
Controlled mussel breeding poses many uncertainties. Last year both hatcheries in the project produced fewer viable juveniles than in previous years. Biologists are still examining water quality and other factors for possible explanations.
To boost the breeding effort, the Park Service is working with state wildlife agencies to transplant mussels to the park. The relocated mollusks come from other locations where they are under pressure, either from sedimentation or altered water temperatures caused by new dams.
"We're not putting all our eggs in one basket," said Steve Bakaletz, a National Park Service biologist. "We're taking adults that are stranded on the island of ecology. We've got the free-flowing territory here, and when they get back to normal temperatures, they can pick up where they left off and complete a normal lifecycle."
Next year the team will begin measuring the effectiveness of the four-year breeding program and the viability of reintroduced mussels. This summer, the park also released a plan that outlines future alternatives to protect mussel species and other aquatic resources.
Meanwhile, the Cumberland elktoe, combshell, bean, tan riffleshell, and the little-wing continue to face a threat that seems as old as the hillscoal mining.
After years of decline in the Tennessee Valley, coal mining has resurged in recent years thanks to newly available earth-moving equipment. Some conservationists express concern that current mining practices are drastically altering natural landscapes and sending acidic drainage into streams essential to aquatic life.
"With the increase in coal mining, there seems to be a total disregard for water quality," Ahlstedt, the retired USGS biologist, said. "People who raise concerns about water quality get branded as environmentalists or wackos."
"But that isn't the way it should be," he added. "This is water that everybody should use, not just fish and mollusks. I'm concerned that any recovery that has happened naturally could turn around in a heartbeat."
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