Growing up in Georgia, I spent a lot of time on Georgia’s coastlines exploring the amazing creatures in our local salt marshes. As a kid learning about the Spartina grasses, fiddler crabs, oysters, periwinkle snails and other fauna and flora of the region, my scientific interest grew, and this encouraged me to become an ecologist studying those same marshes today. I graduated with a biology degree from Georgia Southern University in 2019, and I am currently a Ph.D. student in Ocean Science and Engineering at the Georgia Institute of Technology. I am also a research trainee with Georgia Sea Grant and work with Tom Bliss at UGA Marine Extension and Georgia Sea Grant’s Shellfish Research Lab.
Oysters are a critical resource to Georgia’s coastal regions. The Eastern oyster (Crassostrea virginica) provides important services to the ecosystem and the communities around it (as reviewed by Grabowski and Peterson, 2007). The structures their shells form, known as oyster reefs, provide physical protection to the shorelines, preventing erosion and forming a habitat for fish, crabs, snails, and other species. The oysters themselves filter water, cleaning it of pollutants and algae, and they also sequester carbon from the ecosystem into the sediment. Farmed and harvested oysters are also a thriving fishery – filling the bellies of many restaurant-goers across the Southeastern U.S.
However, wild oyster populations in the U.S. have declined over the last several decades due to pollution, unsustainable fishing practices, storm damage, sea level rise and more. Worldwide, oyster reefs are estimated to have decreased by 85% globally, and many reefs in the Southeastern U.S. are in poor health (Beck et al. 2011). Therefore, solutions are needed to improve reef health in Georgia and restore the beautiful oyster reefs that make our shorelines stable and productive.
The good news is there’s still hope for the natural reefs of Georgia! Oysters have many predators, including blue crabs (Callinectes sapidus). Oysters can sense chemicals from the urine of blue crabs that warn them of being eaten. The chemicals, called homarine and trigonelline, cause young oysters to strengthen their shells during the growth process, causing them to be 30-50% harder to crush by predators like crabs and improving their survival. Using homarine and trigonelline in the hatchery, we can “trick” oysters into strengthening their shells and use them for reef restoration and living shoreline efforts, ensuring better survival of restored oysters.
Sarah Roney pours a mixture of homarine and trigonelline, which are chemicals found in blue crab urine, into the hatchery tanks filled with juvenile oysters. Over several weeks, these oysters will grow significantly stronger than untreated oysters.
My work at the Shellfish Research Lab on Skidaway Island is focused on doing just that – strengthening young oysters to improve their ability to survive predators on restored reefs. Because wild oysters prefer to settle on established reefs, putting out oysters that can survive longer stimulates natural reef settlement and improves the overall health of Georgia’s reefs. Using this technique, we can not only restore the oyster reefs that have been lost, but we can also create “living shorelines”, which are biological engineering solutions to prevent erosion and stabilize shorelines. With heavy ship and boat traffic through the Savannah waterways, this could have huge impacts on stabilizing shorelines in Georgia.
My work on this project has been very exciting, and every time I go into the marshes on the banks of Skidaway Island, I’m reminded of my marsh exploration as a kid. Now, I get to restore and conserve the marshes that remind me of home. More than that, I get to combine ecological principles with practical application and return to the roots of scientific investigation – using what we learn to find solutions on how to preserve the shorelines we all love.
References:
Grabowski, J. H., and C. H. Peterson. 2007. Restoring oyster reefs to recover ecosystem services. Pages 281–298 Theoretical Ecology Series. Elsevier.
Beck, M. W., R. D. Brumbaugh, L. Airoldi, A. Carranza, L. D. Coen, C. Crawford, O. Defeo, G. J. Edgar, B. Hancock, M. C. Kay, H. S. Lenihan, M. W. Luckenbach, C. L. Toropova, G. Zhang, and X. Guo. 2011. Oyster Reefs at Risk and Recommendations for Conservation, Restoration, and Management. BioScience 61:107–116.