Fishing for Clues to Mussel Decline in Horse Lick Creek

Collaborative project supports mussel restoration in Kentucky

CATT Team member Lilly O'Dea with mussel silo. Photo by Anna Walker.
CATT Team member Lilly O’Dea with mussel silo. Photo by Anna Walker.

How do U.S. Forest Service research scientists take their experiments from the laboratory to the field?

For a first-hand look at the field sampling and data collection, collaboration with Forest Service and university partners, and extensive planning that happens behind the scenes, I spent a day with the Forest Service Southern Research Station (SRS) Center for Aquatic Technology Transfer (CATT) team on a stream in the Daniel Boone National Forest (Daniel Boone) in eastern Kentucky.

On this particular day, research technicians from the CATT team – nearly all of whom are undergraduates in forestry fields – completed sampling for a biological index for Horse Lick Creek, an ecologically important but threatened stream on the Daniel Boone. The index shows the quality of an environment based on the types of organisms present.

Many of the technicians I worked with found their way to the CATT team through their university, Virginia Polytechnic Institute and State University (Virginia Tech), which works closely with the Blacksburg unit of SRS, as well as other SRS units and national forests across the Southeast.

The CATT team’s work at Horse Lick Creek is part of a project to restore freshwater mussels in the Daniel Boone and elsewhere. In the past, mussels lived plentifully in the rivers and streams of the Southeast, and they were vital components of these ecosystems. However, long-term disruptions from sedimentation, pollution from agricultural runoff and mining, and dams, among other issues, have endangered many of the hundreds of mussel species endemic to the region. The loss of mussel populations suggests a fundamental impairment of streams that affects all users of freshwater resources.

Research for the restoration project is led by SRS fisheries research biologist Wendell Haag, who works closely with partners from the Daniel Boone, Kentucky Division of Water, Kentucky Department of Fish and Wildlife Resources (KDFWR), Kentucky State University, and the University of Kentucky.

CATT team finds an exceptional rainbow darter, which could indicate good stream quality. Photo by Anna Walker.
CATT team finds an exceptional rainbow darter, which could indicate good stream quality. Photo by Anna Walker.

Beth Christensen, wildlife biologist on the London district of the Daniel Boone, joined me on my day in the field with the CATT team. Christensen works with the CATT team and Haag to maintain and monitor experiment sites. Many of the studies’ streams are on national forest land and the Daniel Boone partially funds the mussel project as well. This project is but one example of how research helps to inform management of important resources across the Forest Service.

The project aims to determine specific factors that negatively affect mussel survival and growth, and to identify the sources of these factors. To do so, Haag is using juvenile mussels raised at the KDFWR Center for Mollusk Conservation to assess and monitor stream health.

Freshwater mussels make excellent biomonitors; mussel species have been shown to be particularly sensitive — and to show measurable responses — to changes in their stream environments.

Haag and his cooperators load tiny juvenile mussels into the flow-through silos, then place the silos in stream locations to see how well the mussels grow. This approach allows direct assessment of mussel response to conditions in specific streams. The results of the study will be used by the Daniel Boone to guide stream and landscape restoration efforts for the benefit of mussel populations and stream health in general.

The biological index conducted by the CATT team the day I visited will indicate the general health of the stream based on the macroinvertebrate (organisms without a backbone, including crayfish and water insects) and fish community. High quality streams typically have diverse and abundant species of macroinvertebrates and fish. In this respect, Horse Lick Creek seems to fit the bill.The day I was there, the water was relatively clear and the team identified over 15 different fish species in one small section of the river. Electrofishing, using harmless electrical currents to direct fish towards nets for sampling, was the last step in the week-long biological surveying that included habitat measurements and macroinvertebrate sampling.

“So far this is one of the nicest streams I’ve ever worked on in Kentucky,” says CATT team veteran Lilly O’Dea. After 3 years of completing biological indices of other streams in the Daniel Boone with the CATT team and SRS scientists, results seem to show that the relative health of Horse Lick Creek provides one of the best opportunities for mussel restoration in Kentucky.

Yet despite the apparent high quality of the stream based on the biological index, all is not well in Horse Lick Creek. The stream formerly had one of the most diverse mussel communities on the Daniel Boone, including at least three endangered species, but mussels have nearly disappeared from the stream in the last 30 years. Because mussels are useful biomonitors, their disappearance suggests that something has severely degraded the stream environment. SRS scientists and collaborators hope to find clues to what caused the serious mussel declines in the stream using biomonitoring combined with an array of other studies.

As I worked with the CATT team, held a live fish for the first time, and spoke with project collaborators, I appreciated the amount of work that goes into an experiment of this type, and I saw the important ways universities, national forests, SRS, and other groups work together to make progress in conservation of our natural resources.

Streamside, an eastern box turtle with egg. Photo by Anna Walker.
Streamside, an eastern box turtle with egg. Photo by Anna Walker.

For more information, email Wendell Haag at

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