Seagrass Mapping and Human Impact Evaluation Using Remote Sensing Imagery at Core Banks, North Carolina

Abstract

Seagrass can provide key ecological services to neighboring habitats in tropical and temperate regions, but evidence shows that they are experiencing significant widespread decline. Coastal human population pressures have played a most important role. This study focused on the damage of boating, propeller scars, which may lead to direct loss of seagrass and increased susceptibility of seagrass beds to damage from hurricanes. The goal of this study is to explore the methods for seagrass mapping based on remote sensing imagery, and to evaluate the impact of human activities on seagrass beds. A transect at Core Banks in Beaufort, NC was selected as the study area. Data sources for this study includes unoccupied aircraft system (UAS) surveyed color mosaics (2.5- to 3-cm pixel size), and high resolution multispectral satellite imagery (RapidEye. 5-m pixel resolution). Based on the analysis, this study provides a successful application of Object-Based Classification in classifying coastal submerged areas in UAS images; human activities have been proven to have lasting effects on seagrass habitat, since seagrass in scar-affected regions has a greater rate of both growth and decline, and scars in areas with higher density of seagrass are more likely to recover. In addition, this study also shows that automated seagrass mapping is feasible using high-resolution satellite imagery and a newly developed index, ReGNDVI (Red Edge-Green NDVI), which has the potential for large-area seagrass mapping. The findings of this study provided useful suggestions on conservation of coastal areas.