New Job Opens Eyes to Mussels

Southern rainbow mussels (Melissa Keneely/DNR)

By Melissa Keneely

When you think of rare animals, freshwater mussels are probably not the first animals that come to mind. Yet mussels rank as one of the most imperiled groups of animals on Earth. An estimated 70 percent of all known freshwater mussel species are considered at risk of extinction in the near future.

As a seasonal field technician working with DNR Nongame Conservation Section aquatic biologists, I’ve had the awesome job of working with these unique creatures all summer. (Nongame Conservation’s focus is conserving hundreds of rare animal and plant species throughout the state, plus the natural habitats they need and other native species not legally fished for or hunted.)

Mussels are especially interesting due to their unique life cycle. To develop, larval mussels must attach to the gills of a host fish. Once attached, the larvae grow into juvenile mussels. They then drop from the fish’s gills and settle into the substrate to mature into adults.

During a recent week, we were sampling mussels in the lower Flint River Basin in southwest Georgia. When we got to the first site, at Ichawaynochaway Creek, we took quick water-quality measurements and then began the survey, which worked like most mussel surveys. Outfitted with wetsuits, masks and snorkels, we lined up in the stream and, moving slowly together, used our hands to feel along the bottom, searching for these sometimes tiny but always marvelous animals.

Afterward, we identified the mussels by species and sex, and noted any reproduction. Any tagged mussels found were recorded. A small, plastic tag was adhered to the shell of new mussels collected. All were returned to the stream to track their growth and survival in following years, data that will help us better understand and conserve each
species.

Identifying and tagging mussels (Melissa Keneely/DNR)

Mussels are incredibly important in ecosystems. In many areas, they are considered a keystone species (one on which other species in an ecosystem depend). Their life history as filter feeders and burrowers results in the significant production of food and habitat for many other animals. Mussels themselves end up being food for several species.

Mussels can improve water quality in streams by filtering algae and nutrients from the water column. The shells of dead mussels may even increase the calcium concentration in low-calcium waterways.

As noted, however, many mussel species have become threatened, endangered or even gone extinct. Significant threats include habitat degradation and water quality decreased by pollution. Since many mussel populations are already small, vulnerable species are a special concern for conservation. We found one of these species, the state-threatened Anondontoides radiates or rayed creekshell, during our survey at Ichawaynochaway Creek.

The complex life cycle of such an inconspicuous group of animals, and the major importance of those animals in so many different ecosystems, amazes me. The excitement of running your fingers through the sand in a stream bed and discovering a mussel is worth the hard work and long days in the field, especially when you find an endangered species thriving in an ecosystem.

I’ve not had much exposure to mussels before, so this job has been eye-opening as to the range of mussel species that are so vital to various Georgia habitats, and how much these species need our help!

Shinyrayed pocketbook (Melissa Keneely/DNR)

P.S. While late-July rains had many creeks swollen, some remained low enough for sampling, including Spring Creek in southwest Georgia. Nongame Conservation sampled the Miller County creek as part of an ongoing evaluation of stream flows on mussel populations there. Of 355 mussels found, 35 were federally endangered shinyrayed
pocketbooks or oval pigtoes. The shinyrayed pocketbook is regarded as one North America’s most beautiful mussels. The one pictured certainly lived up to the claim!

Melissa Keneely is a recent graduate of UGA’s Warnell School of Forestry and Natural Resources.