Sapelo Island is a barrier island on the Georgia coast. The island trends nearly northeast-southwest, and is about 19 kilometers (12 miles) long and 5 kilometers (3.1 miles) wide; it is located between latitudes of 31° 32.3' and 31° 22.8' N. Sapleo and most other Georgia barrier islands are composed of sediments formed by two shorelines separated in geologic time: the Silver Bluff shoreline, which was during the Pleistocene Epoch, and the modern one. These overlapping shorelines partially control the distribution of modern ecosystems on the island.
Ecosystems on Sapelo include salt marshes, maritime forests, grasslands, beaches with extensive back-dune meadows, and freshwater ponds. The climate is temperate to subtropical, with temperatures ranging from an average high of 90°F in the summer to 50°F in the winter, and rarely goes below freezing. Rainfall is about 50 inches/year, with most precipitation during hurricane season (May-September). Hurricanes, however, rarely affect the Georgia coast, with the worst recorded one having been in 1898.
Humans have interacted with Sapelo ecosystems for more than 4,000 years, starting with Native Americans (the Guale people). The Guale were later succeeded by the Spanish (16th-18th centuries), the French (18th century), British (18th century), and Americans (18th century through today). Enslaved Africans were brought to the island during the 18th and 19th centuries as laborers for plantations, and inland ecosystems of Sapelo were altered considerably by this agriculture. People descended from these Africans still live on the island in Hog Hammock, representing the only Gullah/Geechee community on any Georgia barrier island.
American businessman R.J. Reynolds bought the island in 1934, and later created the Sapelo Island Research Foundation and worked with ecologist Eugene Odum to found the University of Georgia Marine Institute. The Institute has conducted seminal research on salt-marsh ecology and other aspects of natural communities on the island. Reynolds' widow, Annemarie Reynolds, sold the island to the state of Georgia, and most of the island is now managed by the Georgia Department of Natural Resources. However, the western edge of Sapelo is classified as the Sapelo Island National Estuarine Research Reserve, as part of NOAA's National Estuarine Research Reserve system.