Mass coral reef bleaching in Florida as ocean temperatures hit 100 degrees

Scientists are racing against time to save as many specimens as possible.
Dead elkhorn coral at Sombrero Reef in the Florida Keys. The white areas are bleached coral, the brownish orange patches are "tissue slough", coral tissue that has died before it has a chance to bleach.
Dead elkhorn coral at Sombrero Reef in the Florida Keys. The white areas are bleached coral, the brownish orange patches are "tissue slough", coral tissue that has died before it has a chance to bleach. Coral Restoration Foundation

As the western United States continues to battle extreme temperatures, the waters off southern Florida are also heating up. Ocean temperatures reached unprecedented 100 degrees Fahrenheit in some places, as a mass bleaching event and die off from these scorching ocean temperatures is spreading across the reefs near Miami and the Florida Keys. 

[Related: Fish poop might help fight coral reef bleaching.]

Coral reefs are vital ecosystems, housing marine life from smaller fish up to turtles and sharks. They also buffer coastlines from increasingly chaotic storms. Climate change is one of the greatest threats currently facing coral ecosystems, as rising temperatures contribute to the scale and frequency of bleaching events and infectious disease outbreaks. When the water gets too warm, coral can become stressed and express algae living in their tissues, thus turning white. Corals are more likely to experience die-offs during these bleaching events. 

Scientists are now on a rescue mission to save the region’s coral species from extinction. Coral experts expect a “complete mortality” of the bleached reefs around the Florida Keys in only a week, and fear that other reefs deeper in the ocean could face this same fate.

“This is akin to all of the trees in the rainforest dying,” Florida Aquarium director and senior scientist Keri O’Neal told CNN. “Where do all of the other animals that rely on the rainforest go to live? This is the underwater version of the trees in the rainforest disappearing. Corals serve that same fundamental role.”

The University of South Florida and Florida Institute of Oceanography’s Keys Marine Laboratory (KML) is currently housing more than 1,500 coral specimens in an effort to save them. The corals were harvested over the past week from offshore nurseries and parent colonies. 

“For years we have been developing the infrastructure capacity to support reef restoration efforts that enable KML to temporarily house corals during emergencies such as this,” said KML director Cynthia Lewis said in a statement. “Typically, water temperatures at this time of year are in the mid 80s, but we are already recording temperatures of 90 degrees. It is very alarming.” 

This summer’s extreme heat and a lack of rainfall in Florida pushed water temperatures around the Sunshine State to some of the highest levels observed around the world. The National Buoy Center recorded a temperature of 101.1 degrees at a depth of five feet on Monday July 24 in Florida Bay. Other stations hit saw temperatures in the mid to upper-90s. While the most significant concentration of Florida coral isn’t located in Florida Bay, the coral around the Florida Keys still experienced temperatures topping 90 degrees.

[Related: To save coral reefs, color the larvae.]

“Climate change is our present reality,” Coral Restoration Foundation CEO R. Scott Winters, said in a statement.  “The impact on our reefs is undeniable. This crisis must serve as a wake-up call, emphasizing the need for globally concerted efforts to combat climate change.”

The National Oceanic and Atmospheric Administration (NOAA) raised its coral bleaching warning system to their highest level (Alert Level 2) for the Florida Keys. This level means that the average water temperatures have been about 1.8 degrees above normal for at least eight consecutive weeks. The Florida Keys are expected to remain at Alert Level 2 for at least nine to 12 weeks.