Charles Darwin didn’t actually visit Belize’s reef, but after talking to other naturalists who had, he described it as “the most remarkable reef in the West Indies” in his 1842 book, Coral Reefs of the World. Among his many accomplishments, Darwin is credited with unlocking many of the mysteries of coral reef development, evolution and atoll formation. Atolls in the Pacific Ocean are believed to have formed when volcanic islands sank into the sea, leaving just a rim of growing coral near the surface. Atolls in the Western Caribbean are thought to have a different history. Many scientists believe these circular rims of coral are actually growing to keep pace with rising seas. Belize’s atolls are living, breathing coral reef ecosystems—each with a unique history and a unique character.
Glovers Reef, Lighthouse Reef and Turneffe Reef are three of the four such coral structures in the Northwest Caribbean; the fourth is located near Banco Chinchorro in Mexico. The atolls rise deep from the seabed, beyond the more familiar continental shelf demarcated by the barrier reef. They are each constructed on foundations of Pleistocene limestone ridges that lie on submerged tectonic faults running in a Northeast direction.
Glovers Reef is the oldest (~7,500 yrs) with the best circular shape, a well developed coral rim and the deepest inner lagoon (18m deep) containing over eight hundred patch reefs scattered throughout. A few sandy cayes make up a land surface of only 0.2% of its total size of approximately one hundred and sixty square miles. Although it is ‘oceanic’ in character with clean clear waters, Glovers is occasionally affected by large river runoff events from the large Honduran rivers to the south. The entire atoll is a marine reserve and is one of the crown jewels comprising Belize’s World Heritage Site. The islands are all privately owned but Middle Caye was donated to the Wildlife Conservation Society and now serves as the headquarters of the reserve and an active marine research station. Glovers Reef has the largest remaining Nassau grouper spawning aggregation site and is a day trip destination option for divers and snorkelers from Placencia, Hopkins and Dangriga.
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Lighthouse Reef is the middle child (~6500 yrs) with a unique oblong shape created by tectonic activity and resulting in the smallest size of just over 120 square miles. It also has a well developed coral rim although the inner lagoon is separated by a fault line serving as the foundation for a line of patch reefs ranging in depth from three to eight meters. The world famous “Blue Hole” lies in the northeastern part of the lagoon and was formed when the rising sea level flooded this Pleistocene cave and collapsed its roof. Again, the few sandy cayes comprise a minimal land surface of only 3%. One of these cayes, Half Moon Caye, was spared from privatization and became Belize’s first protected area. The island and the Blue Hole Natural Monument are part of the World Heritage Site and are managed by the Belize Audubon Society. A number of dive shops throughout the country facilitate day trips to the Blue Hole. There is only one operational resort on the atoll, but several live-aboard dive boats frequent this area.
Turneffe Reef is the baby of the bunch (~5000 yrs) but largest of them all. The almost three hundred and thirty square miles is made up of 20% land, mostly mangrove cayes bordering the shallow semi-enclosed lagoon (up to 8m deep). The lagoon is covered primarily by seagrass although patch reefs can be found in the more exposed northern end. Most of the land is now privately owned. Two small fish spawning sites are protected as marine reserves, but discussions are underway to expand this effort and conserve more of the atoll. It is one of the most important lobster fisheries areas and boasts two research stations managed by the University of Belize and the Oceanic Society respectively. The seagrass beds and patch reefs allow resorts on the atolls to specialize in world-renowned fly fishing. Day trips for scuba diving are also arranged from San Pedro, Caye Caulker and Belize City.
While scientists will continue to study the growth and evolutions of atolls, these incredible watermarks on Belize’s marine landscape should always be conserved and treasured as troves of excitement…and wonder.
