Survival Data of Strengthened and Non-Strengthened Oysters on Two Restored Reefs in Georgia, USA

The eastern oyster, Crassostrea virginica, is known to respond to chemical cues from their predators by strengthening their shell in defense. The chemical cues homarine and trigonelline, found in the urine of blue crabs, Callinectes sapidus, are two metabolic waste products known to cause this inducible defense in juvenile oysters. We tested whether this shell strengthening defense is beneficial for juvenile oysters in a restored reef setting by inducing oyster spat with chemical cues, placing them onto a restored reef and measuring their survival for 50-100 days. The first reef location is a previously restored reef (approximately 10 years old) with limited physical exposure to wind waves and boat wake. Juvenile oysters were placed at this site in September of 2021 and survival was measured for 49 days. The second reef location is a newly restored oyster reef (less than 1 year old) that acts as a living shoreline, with significant exposure to boat wake and wind waves. Juvenile oysters were protected from predation using mesh wrapping with an opening of 1 square cm and placed at the reef site in April 2023, where survival was monitored for 103 days.

Site locations:
Reef 1 (dock site) - 31.988948°, -81.024001°
Reef 2 (living shoreline reef) - 32.067957°,-80.985005°