Think Fast: Coral reef activists Linual Getton, Katy Thacker, and Brian Lapointe work to save the reefs of Jamaica—more than 90 percent are already dead or dying.
Photo: Laara Matsen

Reefs are prevented from forming along much of the tropical South American coast, thwarted by muddy freshwater flows from the vast Amazon and Orinoco river systems on the east, and by inhospitably cold water as far north as Peru on the west. This leaves the region's best-developed reefs in the Caribbean Sea, or far offshore, as in Ecuador's Galapagos Islands.

As with reefs nearly everywhere, tourism, fishing, agriculture, and development are putting extreme pressure on tropical American reefs that are a source of livelihood for millions of people; in such "paradises" as Florida and Jamaica 90 percent of reefs are believed to be dead or dying. Affluence impacts corals in the Caribbean more than population pressure per se, mostly due to enormous numbers of international tourists and the high volume of ship traffic and fishing that help support these countries' high standards of living. Extreme El Niño events are taking a large toll on coral reefs, and a major threat regionwide is human sewage: As recently as 1995, the Pan American Health Organization reported that only 10 percent of sewage from Central American and Caribbean countries was being properly treated before disposal at sea.