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On a sunny day this fall, two Georgia Southern University grad students were waist-deep in the North Newport River near St. Catherine’s Island off the coast of Georgia, while their professor and a team from the Georgia Department of Natural Resources used a winch to lower pallets. full of oyster shells into the water.
The students brought the pallets into place on the muddy river bank. Those pallets, stacked with shells, will provide a hard surface for baby oysters to attach to.
“We’re creating a foundation that wild oysters can populate and grow into an independent reef,” said Cameron Brinton, a marine biologist with DNR.
Oysters used to be plentiful here: Georgia led the nation in the oyster harvest in the early 20th century, according to the University of Georgia. But by the 1930s they were overharvested. A similar story played out in other formerly thriving oyster grounds.
Scientists all along the Atlantic Ocean and the Gulf Coast trying to bring back oyster populations, and not just because it’s a popular food. Oysters are also important to healthy coastal ecosystems. And researchers are now studying how creating new oyster reefs can help fight climate change by sequestering carbon.
Oysters, Brinton explained, are a keystone species. This means they create habitat for other animals, from small shrimp and crabs to fish such as red drum and spotted sea trout that are popular for fishing.
“The majority of commercially and recreationally important species of fish and shellfish will spend some portion of their lives associated with oyster reefs,” Brinton said.
And scientists are studying two ways oyster reefs absorb and store carbon. First, they prevent the sediment in the river from washing away.
“There’s a lot of organic matter in this sediment in the rivers here,” said John Carroll, a professor of biology at Georgia Southern. “So some of that organic matter gets buried behind the reefs.”
Organic matter has carbon in it, so the oyster reefs can store that carbon and keep it from warming the planet.
Second, by stabilizing the shoreline, oyster reefs also help expand marshes—and marshes themselves are many good at storing carbon.
“As the marsh grasses grow towards the reefs, they will also capture a lot of carbon,” Carroll said.
Grist / Emily Jones
So Carroll and his students are helping the Georgia DNR build these reefs. Then they will watch how the coastline changes and how much carbon it stores.
The project is financed by the environmental arm of Yamaha, the boat engine manufacturer. The company, with manufacturing headquarters for the United States in the Atlanta area, is looking for ways to offset its carbon impact, and a project on Georgia’s coast made sense, said sustainability program manager Josh Grier.
“It’s something that our customers who use our products can see,” he said. “We’re not only exploring how we can potentially sequester CO2, but also provide habitat for fish, you know, kind of give back to the communities where our customers use our products.”
Marine combustion — that is, ship and boat engines — produced 23.7 million metric tons, or MMT, of CO2-equivalent emissions in 2020, according to the Environmental Protection Agency. It accounts for a small fraction of overall transport emissions, which were more than 1,500 MMT CO2 equivalent in 2020, mostly from roads.
Yamaha is funding similar research on oyster reefs and carbon sequestration in the Gulf of Mexico through Texas A&M University. The two projects could make for an interesting comparison, Grier said, because the Atlantic coast of Georgia and the Gulf coast of Texas differ greatly in their tides, salinity and other factors that can affect oyster growth.
“They are such different environments that we are very curious to see how the CO2 sequestration manifests itself over time,” Grier said.
Once researchers are able to quantify the carbon storage, Carroll said, he hopes Yamaha and other companies will want to fund more oyster reefs.
“There’s a lot of need,” he said. “It just comes down to having enough of the material.”
