Coral Coasts Ecosystems

A portion of the Florida Reef Tract extends along the eastern coast of Florida in the Atlantic Ocean. The reefs in this region include hardbottom habitats, inner reefs, middle reefs, and outer reefs.

Hardbottom areas host abundant macroalgae, octocoral, stony coral, and sponges. Seaward of the hardbottom, inner reefs typically crest in 3-4 meters of water. The substrate for inner reefs consists of material from relict limestone and worm reefs. Macroalgae and small octocorals characterize these habitats.

Middle reefs crest in about 6-8 meters of water, and they have high concentrations of octocorals. Many stony corals are also present in this ecosystem, such as great star coral (Montastaea cavernosa) and massive starlet coral (Siderastrea sidereal). Outer reefs feature higher relief than preceding reefs, and they crest in 15-21 meters of water. Outer reefs contain the highest diversity and abundance of fixed(sessile) reef species. Octocorals, large barrel sponges, and stony corals are common to these reef ecosystems.

The Florida Keys are surrounded by reefs that extend west to the Tortugas Banks. Three habitats are found in the Florida Keys: hardbottom, patch reefs and bank reefs. Hardbottom is the most extensive habitat; it consists of rock colonized by calcifying algae, sponges, octocorals and stony corals.

Patch reefs are dominated by stony corals, particularly boulder star coral (Montastraea annularis). These habitats are concentrated in north Key Largo, near Elliott key, and in Hawk Channel between Marathon Key and Key West. Farther seaward, bank reefs feature ridges and channels built by elkhorn coral (Acropora palmata). Also known as the forereef, this habitat is a popular destination for snorkelers and scuba divers.

West of the Florida Keys lie the Tortugas Banks, which developed on Pleistocene-era karst limestone. The most common coral species in this ecosystem is Montrastraea cavernosa. Although coral species diversity is low in the area, it supports a major fishery that is dependent on the reef ecosystem.

Off the west coast of Florida in the Gulf of Mexico is the West Florida Shelf, which supports scattered reef ecosystems. The rock substrates in places such as Pulley Ridge and the Florida Middle Grounds have been colonized by Scleractinian corals, octocorals, black corals and sponges. Communities of diverse marine organisms rely on these ecosystems, and a number of these locations have been designated as Marine Protected Areas or Habitat Areas of Particular Concern by the Gulf of Mexico Fisheries Management Council.

Because of its geographical isolation, the Hawaiian Archipelago features high rates of endemism in reef organisms, meaning many species are found nowhere else on earth. This condition is common in both the main Hawaiian Islands and the Northwestern Hawaiian Islands (NWHI).

Reef ecosystems around the eight main Hawaiian Islands include non-structural reef communities, fringing reefs and barrier reefs. Over 400 species of algae have been identified in these ecosystems. The highest levels of coral species diversity are located at the islands of Oahu and Hawaii. There is also rich biodiversity of invertebrate organisms throughout the main Hawaiian Islands, including over 1,000 species of mollusks.

The NWHI comprise the older portion of the Hawaiian Archipelago. This area consists of mostly uninhabited islands, atolls, and shoals stretching for thousands of kilometers northwest of the main Hawaiian Islands. The NWHI is extremely remote, and consequently it hosts a unique and mostly undisturbed reef ecosystem. In addition to corals and algae, these reefs include sharks, sea turtles and monk seals. Many rare and endangered species are present in these reefs. The NWHI is one of the last reef ecosystems in the world to be virtually unaltered by man's activities.