ABSTRACT
Most of the atolls of the Western Atlantic are found along the coasts of Central America. Five occur east of the continental shelf on volcanic bases of the Nicaragua Rise, a tectonically active area that marks the separation between the Caribbean and the North American plates. These lie in the path of the Caribbean Current and trade winds from the east–northeast. All develop submerged rims on their eastern (windward) sides and are open to the west. Three additional western Caribbean atolls are located within the Gulf of Honduras seaward of the Belize Barrier Reef. Here, the Cayman Current, an arm of the Caribbean Current or its spinoff eddies, accompanies trade winds and waves from the east–northeast. All three reside on tilted fault blocks on or near the continental edge and have surface-breaking rims that are best developed on the windward side. Turneffe Reef is distinctive in its more inland position and the development of a lagoon dominated by mangroves, and it is the only Western Atlantic atoll with an open rim. A fourth atoll, Chinchorro Bank, is found on the same fault block as Turneffe and is in the path of the Cayman Current, an arm of the Caribbean Current. Alacrán Reef is found on Mexico’s Campeche Bank where it is washed by the Yucatan Current. Hogsty Reef is the only atoll among the Bahamas reefs, where it is near the path of the Antilles Current. Tides range from 0.3 m offshore Belize to 0.9 m at Hogsty; the others are intermediate. Rocas Atoll is likewise the only atoll in the Western Atlantic outside of the Caribbean Sea. It is in the flow path of the South Equatorial Current and the intense flow of the North Brazil Current, and it has a tidal range of almost 2 m.
