Gray's Reef


Gray's Reef is one of the largest near shore live-bottom reefs of the southeastern United States. The sanctuary is located 32 kilometers (17.5 nautical miles) off Sapelo Island, Georgia and encompasses 58 square kilometers (17 sq. nautical miles) of live-bottom habitat.

Gray's Reef is a submerged hard bottom (limestone) area that, as compared to surrounding areas, contains extensive but discontinuous rock outcropping of moderate ( 6 to 10 feet) height with sandy, flat-bottomed troughs between. The series of rock ledges and sand expanses has produced a complex habitat of caves, burrows, troughs, and overhangs that provide a solid base for the abundant sessile invertebrates to attach and grow. This rocky platform with its carpet of attached organisms is known locally as a "live bottom habitat". This topography supports an unusual assemblage of temperate and tropical marine flora and fauna. Algae and invertebrates grow on the exposed rock surfaces: dominant invertebrates include sponges, barnacles, sea fans, hard coral, sea stars, crabs, lobsters, snails, and shrimp. The reef attracts numerous species of benthic and pelagic fish, including black sea bass, snapper, grouper, and mackerel. Since Gray's Reef lies in a transition area between temperate and tropical waters, reef fish population composition changes seasonally. Loggerhead sea turtles, a threatened species, use Gray's Reef year-round for foraging and resting and the reef is part of the only known winter calving ground for the highly endangered northern right whale. Fossil bivalves and gastropods , and mastodon bones located in this area indicate that the reef was once a shallow coastal environment and an exposed land form as recently as 10,000 years BP. As a terrestrial environment there may exist at Gray's Reef extant prehistoric cultural resources.