Bleaching threatens South Florida reefs

An ashy pallor has spread across South Florida’s coral reefs over the past few months, as stressed corals expelled the algae that gives them color.

The worst case of coral bleaching since surveys began in 2005 struck reefs from the Florida Keys through Martin County, harming the base of the region’s most biologically productive and economically important marine ecosystem.

A survey coordinated by The Nature Conservancy, involving 13 dive teams from government agencies, universities and non-profit groups, found that 21 to 50 percent of colonies checked in the Keys, Broward County, Biscayne Bay and Martin County had bleached or turned pale. Palm Beach County saw less bleaching, with three to 6 percent of colonies affected.

“It’s really widespread,” said James Byrne, Marine Science Program Manager for The Nature Conservancy. “We’ve seen it in past years in one or two areas, but we’ve never seen it across the whole reef.”

Corals, tiny animals that build skeletons of calcium drawn from seawater, contain photosynthetic algae that provides them with energy and gives reefs their rainbow colors. When stressed, the corals expel the algae, making the corals more vulnerable to disease.

Often compared to tropical rainforests for their biological diversity, coral reefs provide habitat for a vast variety of fish, crustaceans, sponges and other sea creatures. The are a vital part of the South Florida tourist industry, supporting fishing, diving and snorkeling businesses.

It’s too soon to know the impact, but scientists will be watching over the next few months to see if the coral recovers, Byrne said. They may well recover without damage, if no further stresses