Record high sea temperatures over the last few months have caused mass coral bleaching events on reefs across the Florida Keys. On July 24, sea temperatures in the Florida Bay hit a record-high temperature of 101.1 degrees Fahrenheit. Some reefs in the Keys, such as the Sombrero Reef, have had a 100% mortality rate due to bleaching.

“A coral bleaching event is when coral expels algae that lives inside of its tissue. This happens because hot water stresses the coral, and the coral’s stress response is to get rid of this algae. The algae provides about two-thirds of the energy a coral needs to live. So when it gets rid of this algae, not only does it get rid of its food source, but also its color,” Marine Science Honors teacher Nicolas Quintairos said.

This most recent coral bleaching event is damaging an already degraded environment, as only about 10% of coral worldwide are located in the Keys — compared to the 1970s. The full scope of damage will not be known for months, but estimates say that 90% of all coral in The Florida Keys have been bleached.

In the long term, Quintarios believes it could take decades for the coral to recover to how it was before the bleaching event. 

“Coral takes a really long time to grow and most coral species, especially the stony corals which build the reef, take decades, if not hundreds of years to mature,” Quintairos said.

The dying coral also has effects on the local marine ecosystems. Coral provides food for many tropical fish, and its destruction could lead to a drop in their population. These fish are vital to the local tourism and fishing industry, so their population decrease has the potential to harm these local industries.

However, as temperatures have cooled since summer, some say that the effects have been exaggerated.

“It’s not as bad as everyone is saying it is, but it is enough to cause a lot of worry,” local Dive Master Christopher Cacciola said. “Coral can get stressed and that stress is going to be visually represented by a change of color and then eventually over time, it will start bleaching. So just because a coral is stressed and it looks like it’s bleaching doesn’t mean that it can’t recover after the sea temperature drops. So it kind of just depends on what, at what point you were out there, you know, because they can get that color back a little bit.”

Despite this more optimistic view, Cacciola says he saw around 80% of the coral bleached on his last visit to the Keys. Fear of bleaching events in the future has prompted some coral restoration organizations to consider moving their coral north in hopes the water temperature won’t be as hot during the next heat event.

Quintairos expresses his frustration over the event and stresses the need to restore these reefs in the future.

“It’s just really sad to see, and hopefully we can come up with ways to restore the reef and have a better approach to restoring reefs in the future,” Quintairos said.