It’s a clear Monday morning in May on the banks of the Ashepoo River in an area called Bennett’s Point.
A group of seven Clemson students and their professor, Caye Drapcho, sit inside the Michael D. McKenzie Field Station and listen to a series of presentations about oyster reef construction, living shorelines and stormwater management by Ben Stone and Al Segars ’74, who work for the S.C. Department of Natural Resources.
They had arrived late the night before after a trip from Clemson that was longer than anticipated due to a flat tire, but they’re engaged and eager, knowing they’re about to put the theory of the last semester into practice.
Presentations complete, we apply sunscreen, grab our life jackets and climb onto the boat. We head down the Ashepoo River at a slow pace, with Segars and Stone taking time to talk about estuaries and marshes, and the biological and economical importance of those. You can see along the edge of the river where the shoreline has eroded, some of which is the result of recent hurricanes, which have not treated this area well.
Marshes may evoke only images of mosquitoes and mud, but they are a vital part of our ecosystem. Segars characterizes marshes as “the nursery for all sea life,” and touts their other important functions as well: slowing erosion, filtering impurities before they reach the ocean, mitigating storm surges. Protecting the marshes is not just an ecological imperative, it’s an economic one as well. Marshes are the bedrock of the seafood industry (a $40+ million industry in South Carolina), and they protect inland development from stormy seas and flooding.
We spot dolphins nearby, including two babies just getting the hang of how to smoothly come out of the water and slide back in. Birds are in abundance, and the sky is that kind of blue that reminds you of the best day you ever spent outside on the water.
Oysters not only serve as great items on your menu; they also filter impurities from coastal waters, and oyster reefs provide habitats for fish, shrimp, crabs and other marine life while they slow erosion and protect shorelines.
Globally, 85 percent of oyster reefs have been lost because of overharvesting or habitat degradation. Disease, development and algal flows have contributed to the decimation. In South Carolina, nearly half of our oyster reefs have disappeared in the last century.
If there are no oyster reefs, there’s no place for oyster larvae to settle in and develop.
So scientists and conservationists have been trying to figure out a way to help mother nature — by creating new oyster reefs. Several ways are being tested, and Stone and Segars point them out as we travel down the river. Loose oyster shells can be shot out by a water cannon on a barge. Mesh bags of oyster shells can be stacked (after the shells are quarantined for six months to make sure they are free of disease and “hitchhikers”). Oyster castles are stackable blocks constructed of recycled oyster shells and concrete that provide a hard service to which oyster larvae can attach and begin to grow.
All of these have had some success, but the solution that Stone and Segars have found effective for their uses is elegant in its simplicity. They began using discarded crab traps that they acquired through donations from commercial crabbers and abandoned traps removed by SCDNR personnel or from beach cleanups.
“We close all the funnels on these traps and repair them with zip ties,” said Stone, “so they no longer capture crabs or other marine animals. We then coat them in a thin layer of tile mortar so that it creates a hard surface for larval oysters to attach to and grow into new oyster reefs.” The crab traps are then placed in groups in the pluff mud during the spring and summer months when the oysters are spawning to increase the chances of attracting larval oysters to attach. Fastened down with re-bar, they slowly create new oyster reefs which provide additional ecological benefits. The structure absorbs waves, and as the waves roll over it, the sediment drops behind it, rebuilding the marsh land behind the reefs.
It’s a good but not perfect solution. It’s labor-intensive, and there’s work to be done in figuring out the best coating to ensure maximum attachment. So in 2012, Segars contacted Drapcho, a biosystems engineering professor at Clemson, to ask if her students might be interested in exploring the best surface material for manufactured oyster substrate — “developing a better mousetrap,” as he puts it. Their constraints? “It has to be inexpensive and fairly simple.”