This May marked the first time any species of Caribbean coral was designated as threatened under the federal Endangered Species Act (see "Clouds Over the Coral," Features, March/April 1999). The two species added, staghorn (Acropora cervicornis) and elkhorn (Acropora palmata), have both suffered a 97 percent decline since the late 1970s due to a combination of disease and human disturbance. By far the greatest culprit, however, is coral bleaching caused by rising ocean temperatures.
Most coral have a narrow temperature range in which they can thrive, and just a few degrees of change over time can cause the polyps to lose the algae that give them their distinctive colors, resulting in the telltale white appearance of affected coral. Because 70 percent of corals" food comes from the algae, the loss of these plant forms means slow death by starvation. Rising ocean temperatures have been widely linked to human-induced global warming. The National Marine Fisheries Service is now in the process of creating new regulations to protect coral.