"100% coral mortality" found in coral reef restoration site off Florida as ocean temperatures soar

Coral reefs play a vital role in the overall health of the planet. And off the coast of Florida, they're in jeopardy, as the relentless heat continues.

The Coral Restoration Foundation said in one coral reef restoration site off the state's coast, the extreme temperatures have proved deadly.

"On July 20th, CRF teams visited Sombrero Reef, a restoration site we've been working at for over a decade. What we found was unimaginable — 100% coral mortality," said Phanor Montoya-Mayoa, a restoration program manager at the foundation who has a doctorate in biology. "We have also lost almost all the corals in the Looe Key Nursery in the Lower Keys."

Sombrero Reef is a protected area off the Florida Keys, just past Marathon. It's a popular site for snorkelers and divers as the area is home to star corals that are considered endangered under the Endangered Species Act. The Coral Restoration Foundation has been on a mission to restore the reef, spending years planting and protecting various corals.

But extreme heat is deadly for the ocean animals. When ocean temperatures become too warm, the algae that normally live within the coral's tissues come out, causing the animals to turn white. This is known as coral bleaching. While bleaching events aren't necessarily 100% fatal for reefs, they do place them under significantly more stress and make them vulnerable, especially to future bleaching events.

"The vibrant coral reefs of Florida, crucial to the local community and the state's economy, are facing a severe and urgent crisis due to soaring water temperatures," the foundation says. "The potential loss of coral populations within the Florida Keys National Marine Sanctuary is quickly becoming an alarming reality."

Much of the nation — and the world — has been under the grip of extreme heat this summer. And its impacts go far beyond dangerous heat on land.

In the Florida Keys, ocean temperatures have been unusually high. A buoy off Vaca Key has been seeing temperatures above 93 degrees Fahrenheit — a reading much higher than the monthly average temperature in the area for the entire year. In July, the average temperature for the area is 89.1 degrees Fahrenheit, according to NOAA.

Nearby Peterson Key also saw temperatures above 94 on Monday while even farther north, Butternut Key saw temperatures above 93.

"The corals are pale, it looks like the color's draining out," Katey Lesneski, research and monitoring coordinator for NOAA's Mission: Iconic Reefs, told the Associated Press. "And some individuals are stark white. And we still have more to come."

NOAA has raised its coral bleaching warning system to Alert Level 2 for the Florida Keys — the highest of the agency's five bleaching alert levels. It's expected to remain that way for at least nine to 12 weeks. According to the AP, such an alert means the average water temperatures have been roughly 1.8 degrees Fahrenheit above normal for at least eight straight weeks. 

This level was last reached last August, and bleaching events typically peak in late August or September. But this is the first time bleaching to this extent has been seen before Aug. 1, Florida Keys National Marine Sanctuary research coordinator Andrew Bruckner told the AP. 

"We are at least a month ahead of time, if not two months," Bruckner said, adding that the Florida Keys have lost between 80% and 90% of its reef systems in the last 50 years.

The Upper Keys have not seen as "dramatic declines" as what the Coral Restoration Foundation saw in Sombrero Reef, but the foundation said that what they've seen "underscores the urgency of addressing climate change."

"We are now rescuing as many corals as we can from our nurseries and relocating key genotypes to land-based holding systems, safeguarding our broodstock – potentially, the last lifeline left many of these corals," Montoya-Maya said. 

Florida's coral reef runs more than 350 miles, protecting the peninsula from storms and providing a staple for the state's tourism and food industries. According to the state, the system supports more than 71,000 jobs, generating over $6.3 billion for the economy. Without it, the state can suffer economically throughout the year as well as during hurricane season, which could bring increasingly catastrophic storms – without the natural protection in the waters.

R. Scott Winters, the foundation's CEO who has a doctorate in ecology, evolution and biodiversity, and bioinformatics and computational biology, said that the impact of climate change on coral reefs "is undeniable."

"This crisis must serve as a wake-up call, emphasizing the need for globally concerted efforts to combat climate change," Winters said. "...This is not a partisan issue; everyone will be affected. The climate crisis impacts our way of life and all life on Earth."

In:
• Coral Reef
• Environment
• Florida
• Heat Wave

Li Cohen

Li Cohen is a social media producer and trending content writer for CBS News.