Identifying Sustainable Substrates for Subtidal Oyster Reef Construction

Historically, oyster shell has been the preferred substrate for reef foundations in restoration efforts targeting the eastern oyster Crassostrea virginica. Alternative reef foundation substrates are desirable due to increasing costs of oyster shell. Further, carbonate (CaCO3) based substrates are susceptible to degradation by bioeroders (e.g. Clionid sponges). Oyster demographics, Clionid infestation of oysters and substrates, and characterization of predation sources on juvenile oysters were tracked in a long-term study (54 months) of 80 subtidal oyster reefs constructed in 2012 across salinity gradients in two North Carolina estuaries. Reefs had foundations of either CaCO3-based (oyster shell or marl pebble) or nonCaCO3-based (concrete cobble or granite pebble) substrates. Results indicated estuarine location and reef foundation composition interacted to determine the fate of oyster communities. Continued use of CaCO3-based materials for oyster restoration efforts in regions suitable for boring sponge populations is counterproductive to the intended purpose of restoring oyster communities.Master of Scienc