An extraordinary marine heat wave off the coast of Florida pushed ocean temperatures to 101 degrees Fahrenheit, threatening to wipe out the state’s iconic coral reefs. And the only way to save them is to remove them to land-based labs, where they can survive until it’s safe to return them to their reefs.
But Florida’s coastal water temperatures this year are hotter than ever and warmed much earlier than usual, with temperatures expected to stay abnormally hot or get hotter in the coming weeks, further stressing the state’s coral reefs.
Fortunately the Coral Restoration Foundation is leading a consortium of restoration partners to dive to the stressed reefs, gather targeted coral species, and relocate them to land-based holding tanks with water temperatures suited to their survival. If left on the reefs in the overheated ocean, they most certainly would bleach and even die; corals can recover from bleaching if ocean temperatures cool quickly enough.
Corals get their brilliant colors from zooxanthellae algae, which live inside the corals and provide food. But when ocean temperatures get too warm, the algae turn toxic, and coral try to get rid of the colorful algae as quickly as possible, turning pale in the process — “coral bleaching.”
The ocean absorbs more than 90 percent of excess heat from Earth’s system, attributed to rising greenhouse gas emissions. Reef-building corals thrive in temperatures between 22 and 29 degrees Celsius (73 and 84°F). Florida ocean temperatures for weeks have registered and remain in the low 30s Celsius (low 90s Fahrenheit).
Thanks to a vast network of ocean buoys that regularly observe ocean temperatures and other data, Florida’s CRF anticipated the marine heat wave and, as of July 26, were able to protect “nearly all elkhorn genotypes, and many staghorn, found throughout Florida’s Coral Reef,” according to a blog post by its CEO, Dr. R. Scott Winters.
Related: Why a warming ocean matters
“Yes, the situation is serious,” Winters wrote, “but it is far from hopeless.”
Approximately 25 percent of marine life interact with coral reefs, and in Florida the reefs support more than 71,000 full and part-time jobs and generate more than $6.3 billion from snorkeling, scuba diving, fishing, and other related activities, according to the Florida Fish and Wildlife Conservation Commission.
Since the late 1970s, healthy coral cover in the Florida Keys has declined by 90 percent, prompting NOAA to launch Mission: Iconic Reefs, hoping by 2040 to restore 25 percent reef cover — an area reportedly sufficient to allow the reef to fully restore itself.
But as the marine heat wave rages on, more of Florida’s corals will suffer bleaching, and this year will be a major setback even with CRF’s rescue operation. Such is the damage of our reliance on burning fossil fuels, because the more global heating we generate, the more heat the ocean will absorb, and more marine heat waves will result, threatening coral reefs worldwide.