Remote sensing of live and dead intertidal oyster reefs using aerial photo interpretation in Northeast Florida

Abstract

The eastern oyster, Crassostrea virginica, has been classified as a keystone species as well as an ecosystem engineer because of the significant benefits that oysters and oyster reefs provide. Oyster reefs are being recognized as valuable for shoreline protection within coastal areas. The severe loss of oyster reef coverage has encouraged different types of conservation, mapping, monitoring and restoration efforts throughout its native range. Intertidal oyster reefs are an important habitat as well as an important industry in Florida, which makes accurate habitat monitoring a key element of resource management for this species. This project focused on creating a continuous intertidal oyster reef habitat map in northeast Florida. Existing aerial photography was used to identify oyster reef signatures, and map the distribution of intertidal oyster reefs throughout the study region using ArcGIS software. When accuracy assessment was completed, we found the number of observed agreements was 97% of the total observations. This mapping effort represents the first successful attempt at fine-scale oyster reef mapping across the entire northeast Florida region and resulted in a total of 17,953 individual reefs being mapped, with a total reef coverage of 651.86 ha. By using existing aerial photography, this methodology represents a low-cost method for reef mapping, compared to other methods such as drone imagery or field-based mapping. This baseline map of current oyster distribution will serve many functions for management this particular ecosystem. Future changes to reef distribution can be mapped and used to identify potential negative or positive impacts to the habitat.