In less than 30 years, 3,000-year-old oyster reefs off Florida’s Big Bend coastline have declined by 88 percent, according to UF/IFAS researchers. For residents who depend on the fishing grounds and other coastal resources protected by these reefs, it’s a worrying trend. Now, thanks to an award of up to $8.3 million from the National Fish and Wildlife Foundation’s Gulf Environmental Benefit Fund, a UF/IFAS research team will work to restore these shrinking oyster reefs and help coastal ecosystems — and economies — become more resilient in the face of climate change and rising tides. “This grant is one more way UF/IFAS can help foster sustainable communities and ecosystems on the Nature Coast,” said Jack Payne, senior vice president for agriculture and natural resources. “This work also dovetails with efforts by our state and local partners to conserve land and water resources in our coastal areas,” he said. “This project, which is more than 10 years in the making, includes listening to local concerns about disappearing reefs, our initial field research, a three-year pilot project and finally a full-scale project,” said Peter Frederick, who is one of the primary investigators for the grant along with Bill Pine and Leslie Sturmer. Frederick and Pine are research and associate professors of wildlife ecology and conservation, respectively, while Sturmer is a UF/IFAS extension agent specializing in molluscan shellfish aquaculture.
With a projected start date in 2017, the Recovery and Resilience of Oyster Reefs in the Big Bend of Florida project will target the Lone Cabbage reef chain in the Suwannee Sound. The UF/IFAS team plans to restore 32 acres (encompassing about 2 linear miles) of reef, though the project may expand beyond this area, Frederick explained. Previous research by Frederick and his team, motivated by questions from the oyster fishing industry in the Cedar Keys area, shows that the decline of oysters in the Big Bend region is due to increasing salinity levels in estuaries, which is where freshwater from rivers mixes with ocean salt water, Frederick said. The survival of many plants and animals, including oysters, is tied to these conditions. “When water from rivers decreases — as has occurred in the Suwannee Sound— less fresh water mixes with salt water from the ocean,” said Frederick. “This causes salt levels in the estuary to rise, stressing oyster populations. At the same time, existing oyster reef chains act as a sort of leaky dam to keep some fresh water in the estuaries. As more oysters die, more ocean water mixes with fresh, boosting salinity.” On top of that, reefs made up of dead oysters eventually disintegrate into sandbars. Oysters can’t establish on sand, so the reef can’t regenerate. “More salinity leads to fewer reefs, fewer reefs to more salinity. It’s a negative feedback loop,” said Frederick.
The UF/IFAS project wants to break this cycle by encouraging new oysters to recolonize areas where reefs have degraded. To do that, researchers will install limestone boulders covered in a layer of oyster and clam shell, materials that readily attract new oysters. The boulders won’t go anywhere — they stayed put in Hurricane Hermine — and provide long term stability for the reef. However, restoring oyster reefs isn’t just for the sake of the oysters. “This chain of reefs provides a particular set of ecological services that affect humans on the nature coast,” Frederick said. “Keeping estuary salinity stable is important for maintaining high productivity of fish and shellfish that, like the oyster, do best in that kind of environment.” “A healthy estuary makes for a healthy economy,” Frederick said. “Local fishermen, clam farmers, residents and partner agencies were key to the success of our planning and pilot efforts,” said Frederick, noting that the oyster and clam shells used in restoration were provided by the local clam aquaculture industry. A robust oyster population may have other long-term impacts. As oyster reefs proliferate, they shield the coastline from the ocean’s waves, said Frederick. “Through the buffering action of the reef, our restoration effort makes coastal natural resources more resilient to the threats of climate change and sea level rise,” he said.