MIAMI – A new study shows that Florida's pristine coral reefs are under a growing threat from climate change.
The Miami Herald reported Saturday on the National Ocean and Atmospheric Administration study. According to the study, some reefs could be damaged about a dozen years earlier than previously projected. The study found coral bleaching caused by warmer waters could harms sections of the Dry Tortugas reef tract and reefs in areas off the middle Keys as early as 2030.
Bleaching is potentially deadly to colorful corals and the many creatures that thrive inside coral reef habitats.
The scientists used a supercomputer to crunch data on sea temperatures around the Gulf of Mexico and Caribbean already identified as vulnerable to bleaching outbreaks. Their findings confirmed that bleaching could be widespread by mid-century and revealed the bleaching might start to show sooner in some areas than others.
Scientists consider reefs an important earlier indicator of more serious trouble.
"They're the canary in a coal mine," said the study's lead author, Ruben van Hooidonk, a University of Miami coral expert.
Decades of coastal run-off, fishing and anchors have already done heavy damage, shrinking Florida's reefs to a fraction of their historic range. Swings in temperature add to the stress. Cold water can kill tropical reef gardens. But increases in temperature, even slight ones, can cause coral to spit out life-sustaining algae. Acidification, another malady linked to climate change and rising carbon in oceans, could also weaken reefs.
Until now, bleaching has occurred periodically, but never regularly.
Cool weather, like the recent cool front, give reefs a respite and chance to rebound.
"The Tortugas has looked great," said Frank Wasson, president of Spree Expeditions who captains the MV Spree to the remote islands some 70 miles west of Key West for dive trips in deeper waters where strong currents have helped keep reefs healthy. "Out on the bank, it has been incredibly healthy."
But that could change under new climate conditions. Last year, divers documented widespread bleaching throughout the Keys that could be worsened by forecasts for another El Ni?o weather pattern, said Chris Bergh, the South Florida Conservation Director for The Nature Conservancy. Divers are just now starting to assess damage, he said.
By mid-century, Hooidonk said yearly bleaching will likely occur along large swaths of reefs at the south end of Biscayne Bay past Key Largo and from the middle Keys south to the Dry Tortugas. Corals can survive bleaching if waters cool quickly enough to allow algae to return. But prolonged temperature spikes like those predicted by climate models could spell doom.
Scientists are already on the lookout for corals that do better in inhospitable conditions. They could graft those corals onto threatened colonies to fortify valuable reefs.
More information could also improve existing conservation programs and heighten awareness about the dangers of coral bleaching, already a leading killer of Florida's reefs, Bergh said.
"Those things are already important but they become even more critical knowing that coral bleaching is going to become more of a problem in the future," Causey said.