"You could argue that a complete collapse of the marine ecosystem would be one of the consequences of losing corals," Carpenter said. "You're going to have a tremendous cascade effect for all life in the oceans."
Exotic and colorful, coral reefs aren't lifeless rocks; they are made up of living creatures that excrete a hard calcium carbonate exoskeleton. Once the animals die, the rocky structures erode, depriving fish of vital spawning and feeding grounds.
Experts say cutting back on carbon emissions to arrest rising sea temperatures and acidification of the water, declaring some reefs off limits to fishing and diving, and controlling coastal development and pollution could help reverse, or at least stall, the tide.
Florida, for instance, has the largest unbroken "no-take" zone in the continental U.S. — about 140 square miles off limits to fishing in and around Dry Tortugas National Park, a cluster of islands and reefs teeming with marine life about 70 miles off Key West.
Many fishermen oppose such restrictions. And other environmental measures have run into resistance at the state, local, national and international level. On Sunday, during a gathering of the Convention on the International Trade in Endangered Species of Wild Fauna and Flora, restrictions proposed by the U.S. and Sweden on the trade of some coral species were rejected.
If reefs were to disappear, commonly consumed species of grouper and snapper could become just memories. Oysters, clams and other creatures that are vital to many people's diets would also suffer. And experts say commercial fisheries would fail miserably at meeting demand for seafood.