None The Nature Conservancy in Georgia Press Releases Search All Press Releases Christine Griffiths Phone: (912) 437-02161, ext. 225 Email: cgriffiths@tnc.org

Conasauga River Is Being Re-populated with Freshwater Mussels

Cohutta, GA—August 26, 2003—The biological diversity of the Conasauga River is getting a helping hand from scientists as more than 48,100 mussels have been released into the river system over the past four years, including 37,218 this year.

As part of an on-going project to boost mussel populations, the Tennessee Aquarium Research Institute in Chattanooga, Tenn., has propagated freshwater mussels native to the Conasauga River basin at the Institute's hatchery in Cohutta, Ga. After painlessly infecting specific host fish with the glochidia (parasitic larva) of its corresponding mussel species, scientists collect the developed, yet still microscopic, mussels five to seven weeks later. Then a site is selected to release the mussels.

In its fourth year of propagating and releasing mussels, the program has yet to yield any conclusive results. But scientists are still hopeful.

"We are still early in the program to see any recovery," said Paul Johnson, research scientist with the Tennessee Aquarium Research Institute. "Since mussels are long lived, it will take a minimum of five years before we can find any juveniles. It takes several years to grow to a size where you can find them."

Encompassing nearly 500,000 acres of land (including 119,000 acres in the Chattahoochee National Forest), the Conasauga supports 26 species of rare fishes, mussels and dragon flies, putting the basin in the top six of 2,000 watersheds in the United States in terms of species diversity. With colorful names, such as the Tennessee heelsplitter and southern pigtoe, freshwater mussels have declined significantly in the Conasauga, causing scientists to not only repopulate the river system but also look for the cause.

Particularly sensitive to changes in water quality, mussels are considered an indicator species, similar to the concept of a canary in a coal mine. When mussel populations are healthy and flourishing, it is a good indication that the river system is healthy. But if the mussels are in distress, then the ecosystem is out of balance. Habitat disturbances, such as dredging, the construction of dams, the introduction of non-native invasive species, and the effects of siltation and contaminants associated with construction and agriculture impact the fragile life cycle of mussels and their host fish.

The United States is one of the richest aquatic regions in the world, supporting almost one-third (approximately 300 species) of all known freshwater mussels with about 70 percent of those species considered endangered or threatened, making them one of the most at-risk groups of organisms in the country. Of the 82 known mussel species in Georgia (historically there were 118 known species, but 36 are thought to no longer occur in Georgia), the Conasauga supports eight federally listed species: upland combshell, southern acornshell, fine-lined pocketbook, Alabama moccasinshell, Coosa moccasinshell, southern clubshell, southern pigtoe and ovate clubshell. The river system also supports three species of special concern: Tennessee heelsplitter (a candidate for federal listing), Alabama rainbow and the Coosa creekmussel.

Nature Conservancy staff in the North Georgia Conservation Office in Dalton have been assisting the Tennessee Aquarium Research Institute with the mussel release program, as well as trying to pinpoint the cause for declining mussel populations. This summer, Nature Conservancy staff began a two-year study of toxins in river sediments in order to understand the effect on the growth of mollusks in the Conasauga River watershed. As filter feeders of microscopic food items, freshwater mussels are susceptible to smothering by silt and other sediments in the water and the pollutants carried by these sediments.

"The Nature Conservancy has been a lifesaver, trying to improve the situation for mussels in the Conasauga River," said Johnson, adding that the results of the toxicity work can not only help to shed light on the decline of mussel populations in the Conasauga but can also be applied to other systems to avoid similar problems.

Other project partners include the Tennessee Aquarium Research Institute, U.S. Fish and Wildlife Service, U.S. Geological Survey and the Tennessee Wildlife Resources Agency.

"The mussel release program, combined with other protection and restoration efforts by the Conservancy landowners, other agencies and local industries, will hopefully have a positive effect on the population numbers," said Nate Thomas, field representative with the North Georgia Conservation Office of The Nature Conservancy. "Without the cooperation of our partners and the landowners and industries along the river, our work to boost mussel populations wouldn't be possible."