USING SEDIMENTOLOGY, FORAMINIFERA, AND SEABED MORPHOLOGY TO ASSESS THE ENVIRONMENT OF SUGARLOAF ISLAND, BOGUE SOUND, NC BEFORE AND AFTER A COASTAL SHORELINE STABILIZATION PROJECT

Abstract

Sugarloaf Island is a spoil island within Bogue Sound, off the coast of Morehead City, NC. It acts as a fetch-limited barrier island, protecting the mainland from erosion resulting from wind and wave energy. Currently, the shoreline of Sugarloaf Island is eroding, making it the focus of a shoreline stabilization project. Morehead City’s project plan calls for the installation of wave attenuation devices (WADs), subaquatic vegetation (SAV, i.e., coastal seagrass), oyster reefs, and a rock revetment to try to boost the island’s resilience and reduce erosion. To evaluate the effects of the stabilization structures, this study has utilized sedimentology, foraminifera and side-scan sonar imagery to understand the characteristics of sediment transport and erosion. This study has determined a general sediment transport direction of west to east and a fining of sediment in that direction as well. Following emplacement of stabilization structures, there was a coarsening of sediments around the island. Sorting of beach and nearshore samples was maintained or worsened, whereas offshore sites showed maintained or improved sorting. This study also analyzed living, modern dead, and fossilized foraminifera. Across both sampling times, Elphidium excavatum and Ammonia parkinsoniana were the most abundant species in both the modern dead and the live foraminiferal assemblages. Following emplacement of stabilization structures, where was an increase in living foraminifera, specifically in the onshore samples. Lower numbers of live foraminifera in round 1 samples was likely due to the time of sampling (mid-winter) when reproduction is reduced or paused. There was also a decrease of fossilized foraminifera specimens. These findings are the result of the implementation of stabilization structures, which has reduced wave energy and onshore sediment transport.