Using Oyster Shell Reefs To Counter Sea Level Rise In Louisiana

This article is part of The State of Science, a series featuring science stories from public radio stations across the United States. This story, by Eva Tesfaye, was originally published by WWNO.

On a hot Friday morning, the sun beat down on volunteers gathered at the edge of the water in southern Plaquemines Parish. They passed heavy sacks of oyster shells to each other down a line.

“I feel like I’m gonna have massive biceps after this. It’s definitely an amazing workout,” said Hilary Nguyen, one of the volunteers for the Coalition for Coastal Louisiana, the organization that built the reef.

The volunteers loaded the shells onto boats to use them for building an oyster reef to help slow land loss in Grand Bayou Indian Village.

“The oyster reef is a living thing. Baby oysters are going to attach to it. It’s going to grow. It’s going to become bigger,” said James Karst with the coalition. “But when the sea level rises, because oysters are growing on it, it will grow vertically as well, so it will continue to add protection.”

Louisiana’s land loss is an existential crisis for many of the state’s tribes who live along the coast. Grand Bayou Indian Village, a small community, home to the Atakapa-Ishak/Chawasha tribe, is watching its lands wash away. Nearly 1,000 people lived in the village in the 1940s, but now there are only about a dozen homes raised on stilts right along the edge of the bayou. Boats are the only way to get around.

“You can look at the GPS and it will indicate a different color for where land is,” said Karst. “You’ll be looking at this on the screen, then you’ll look up and there is no land there. It’s just open water.”

Volunteers built the reef by stacking bags of recycled oyster shells in the water, up and down the shoreline. The shells came from restaurants in New Orleans. The coalition recently expanded its oyster recycling services to Baton Rouge.

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It’s the second reef the Coalition for Coastal Louisiana has built in partnership with the Atakapa-Ishak/Chawasha. The first protects the tribe’s Lemon Tree Mound, a piece of sacred land that was once elevated.

“That’s a remnant mound. It’s out in Bay Adams,” said Rosina Philipe, a tribal council member and the tribe’s knowledge holder. “It’s surrounded by water because the land has changed so dramatically over a period of time.”

The reef protecting Lemon Tree Mound was built two years ago. It’s covered with shells, baby oysters, mussels, snails and crabs.

“This is an oyster drill conch. This is a predatory snail that actually eats oysters,” said Richie Blink, who runs Delta Discovery Tours and drove the boat, “So that’s just telling us that there’s oysters that are actually here. Fishermen don’t like these very much.”

Small waves rippled in front of the reef, but behind it, closer to the land, the water was almost completely still, meaning there’s less erosion. At the same time, the tribe knows these reefs won’t be enough to completely stop the land from disappearing, but Phillippe said they’re worth it anyway to buy time.

“It will eventually succumb to the waters in the waves, which is okay,” she said. “But the reef that was created there will serve as not only a marker of where that site was, but it actually encourages marine life to congregate there and to repopulate the area.”

The land where their houses are built could face a similar fate, so the tribe is looking into more solutions such as floating houses and gardens.

“We’re water people, so we’re learning to live with more water now,” she said. “Less land, more water, but we’re still going to be here.”