NOAA: Florida's lethal wave of coral bleaching could be the start of a global event
A lethal wave of coral bleaching spreading across Florida’s reef has reached eight other countries in the Caribbean, Atlantic and east Pacific, raising concerns that a global bleaching event could be unfolding.
In a press conference Thursday, scientists with the National Oceanic and Atmospheric Administration warned that conditions are far worse than in past global bleachings.
“If we compare what is happening right now to what happened in the beginning of past global bleaching events, things are worse now than they were in 2014 to 2017,” when 75% of the planet’s reefs bleached, said Derek Manzello, who coordinates NOAA’s Coral Reef Watch Program. “So Florida is just the tip of the iceberg.”
As ocean temperatures soared this summer, climbing as high or higher than any ever recorded by satellites, bleaching appeared around the Caribbean and Atlantic.
Belize reported bleaching, with Florida coral beginning to turn white after high temperatures caused them to expel their life-sustaining coral. Coral from Cuba to Panama, Puerto Rico, the U.S. Virgin Islands, Colombia and El Salvador also bleached.
In Mexico’s eastern Pacific waters, Manzello said water grew so hot so fast, coral died before they even bleached. Sharks have also fled the reef, he said, and some sea stars have vanished.
“So we need to consider the fact that corals are not the only organisms that are suffering,” he said.
The first mass bleaching appeared in 1982 and 1983, when an El Niño weather pattern started warming Pacific waters, Manzello said. Since then, bleachings have increased in size and severity. One hit in 1998, another one in 2010 and then a prolonged three-year bleaching began in 2014 and ended in 2017.
“So what is concerning us now is that again, we are right on the cusp of a very strong El Niño,” he said.
Florida’s bleaching, which started in July, ignited a widespread rescue effort.
Divers and scientists began pulling still healthy coral from reefs and offshore nurseries, where they’re grown to restock the reef, and moving them to safety in labs. But that’s highlighted another problem: while coral breeding programs have been underway for more than a decade, they haven’t reached the scale necessary to address an emergency like the one unfolding.
“Florida’s corals have never been exposed to this magnitude of heat stress ... All of the data we have at our disposal right now is suggesting that this event is going to become Caribbean-wide."
Derek Manzello, who coordinates NOAA’s Coral Reef Watch Program.
“It is really clear that we need to keep doing what we're doing, but do more of it at a bigger scale,” said NOAA research ecologist Ian Enochs.
Based on an assessment of monitoring, NOAA scientists found temperature highs have been hotter than the previous records for 28 of the last 37 days. That kind of prolonged heat, as well as light, causes stress to build in corals.
On July 16, NOAA issued a severe bleaching alert for the Keys, where bleaching was severe and death likely. The heat also started nearly six weeks earlier than normal and is forecast to continue.
“Florida’s corals have never been exposed to this magnitude of heat stress,” Manzello said.
Severe bleaching alert set to continue
Models forecasting conditions show relief remains months away, unless a hurricane arrives to churn up waters and pull deeper, cooler waters to the surface.
For now, severe bleaching conditions are expected to hit the entire Caribbean by mid-September and continue through October. Florida’s severe bleaching alert will likely remain until mid to late September or early October.
For the 3,800-square mile Florida Keys National Marine Sanctuary, the event has been catastrophic, scientists said. Cheeca Rocks, one of the healthiest reefs and selected as part of the $100 million, 20-year Mission Iconic Reef restoration effort, is nearly all bleached.
Last week, divers began a sanctuary-wide assessment to better understand the variability of the bleaching, said Andy Bruckner, the sanctuary’s research coordinator.
“There are some hopes that some locations to date have exhibited very minimal signs of bleaching and little or no mortality,” he said. Bleaching also varies by species, with boulder coral showing only slight signs. The differences, he said, reflected the amount and duration of the heat. One offshore reef in deeper water showed little stress.
As the heat continues, scientists say they will be closely watching coral bred in labs to withstand warmer waters and planted in offshore nurseries. While some have shown promise, Bruckne said again the scale of operations is too small to keep up with the looming disaster. Other smaller pilot projects may provide some relief, like shading reefs and targeting predators, but they too remain small and in the testing phase.
By spring, once surveys are completed, Bruckner said scientists will have a better idea of the extent of the obvious damage. But long-term recovery can be complicated. Studies have shown that even if they heal, coral grow more slowly and reproduction can slow dramatically for up to four years. They also become more susceptible to disease.
For now, the NOAA scientists say they are bracing for the worst.
“Unfortunately, I believe it is just beginning,” Manzello said. “All of the data we have at our disposal right now is suggesting that this event is going to become Caribbean-wide in the next days to weeks.”
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