This project aims to investigate the transitions in coastal habitats—specifically saltmarshes, oyster reefs, and mangroves—over time, focusing on the Guana Tolomato Matanzas National Estuarine Research Reserve (GTM Reserve) on the east coast of Florida. The study area encompasses regions both north and south of St. Augustine, providing a comprehensive view of habitat changes in this dynamic estuarine system. Using ArcGIS and historical aerial images, the project will digitize coastal habitats over various time periods to track and analyze changes in benthic habitats. The core focus is on the northward expansion of tropical mangroves within the GTM Reserve, a phenomenon driven by tropicalization and climate change. As these mangroves extend into areas traditionally dominated by saltmarsh and oyster reefs, it is critical to understand the ecological implications of this shift. The research will explore how the encroachment of mangroves affects the distribution and health of saltmarsh and oyster habitats, which are vital for providing nursery grounds, shelter, and food for various marine species.