EFFECTS OF AN ARTIFICIAL OYSTER REEF ON THE SURROUNDING ECOSYSTEM NEAR MCCLELLANVILLE, SC

Natural reefs provide habitat, protect against erosion, and provide economic resources for many coastal regions. The artificial Palmetto Plantation Oyster Castle Reef was installed in August 2012 on the northwest bank of the Atlantic Intracoastal Waterway (ICW) northeast of McClellanville, SC, in order to quantify artificial reef influences on this shoreline. Site surveys, including shoreline change analyses, sediment grainsize changes, and oyster recruitment observations, were conducted from June 2012 through October 2013 to address the overall goal of enhancing oyster reefs in this area while stabilizing the adjacent shoreline. This goal was accomplished with the project.

Nine site visits were made to the area, 264 sediment samples analyzed, 852 photographs taken, and seven laser scans conducted. Five control posts were placed in the marsh, and RTK-GPS measurements were used as geodetic control to georectify all data in ArcGIS so that observations, shoreline positions, sediment accumulation patterns, and changes could be documented.

Grainsize analysis shows grainsize decreasing in the entire study area over the period, and laser scans, photographs, and observations clearly show the thickening of mud behind the reef and not in the adjacent areas.

Historical shoreline analyses indicate overall accretion in this area, with the period from 2006 to 2013 showing erosion as prominent. Detailed shoreline studies from this project indicate consistent erosion before installation of the reef, and accretion behind the reef in two lobes.

Oyster recruitment was almost immediate, with clear oyster growth in the second month after installation. The most important colonization and subsequent growth areas are on the front of the reef, the ends of the reef, and on the protected platforms on the front of the reef. Flat surfaces on overturned block ends did not recruit oysters. Oyster growth was highest on the merlons, and in some cases completely closed the gabs between them in just over a year.