Sensitive corals are being relocated from warming waters in the Florida Keys to a temperature-controlled lab, as scientists are preparing for a “super” El Niño that's expected to be as bad or worse than the 2023 record-breaking climate event.
Human-accelerated climate change is increasing the frequency and intensity of extreme weather like this.
Just three years ago, most of Florida's Coral Reef system in the Keys and Dry Tortugas was bleached – that’s when heat causes corals to lose their photosynthetic algae, making them turn white.
Some are able to bounce back from bleaching, but it leaves them susceptible to disease and some ultimately starve to death.
"We're down to less than 3% percent live coral cover on the reefs right now,” said Cynthia Lewis, director of the Keys Marine Laboratory at the University of South Florida's southernmost campus.
For comparison, it used to be 60%-80% live coral coverage back in the 1960s and ‘70s, Lewis added.
While the heat death toll varied by location and species, branching corals like the staghorn and elkhorn became functionally extinct.
"It was extremely traumatic and devastating to everybody, and took a strong mental toll on everybody. Let alone the physical toll of actually moving all these corals in and caring for them,” Lewis said.
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USF and its partners moved more than 5,000 specimens from offshore nurseries and parent colonies to the lab.
"This was definitely an event we had never seen before. I think we're going to see it again this year. We're on that same trajectory," Lewis said.
The researchers have an emergency plan for this El Niño pattern, which is projected to be stronger and last longer than initially thought, peaking this winter and spilling over into next spring.
Some corals will get moved to deeper, cooler depths, while more sensitive ones go to the lab. Others will have to tough out the heat.
"Whatever corals survive are going to be your tough ones that you want to work with coming out of this. But at least we've got other corals, either land-based or deeper, to still have the biomass and the diversity to continue the restoration after the event's over,” Lewis said.
“There is a hope by restoring these small areas of reefs and get them so that they are more resilient and resistant to the current and future conditions that they may be facing on the reef."
After the 2023 bleaching event, the state started paying for the cost of running the lab's temperature-controlled seawater tables, where the sensitive corals are relocated to await cooler temperatures. It also supported a recent expansion of these land-based operations.
“It's basically a saltwater tank, if you will. The ones that that we usually use are maybe eight feet long and four feet wide and a foot and a half deep, and we have seawater flowing through them,” Lewis said. “We regulate the temperature of that water, so … it's never more than 82 degrees, 83 degrees.”
Florida's waters host the only living barrier reef in the continental United States, which not only protects our coast from storms, but also breathes life into the underwater world that draws in tourism dollars.
