Nurseries Help Corals Grow To Restore Reefs For The Health Of The Oceans

This story originally aired on NPR’s All Things Considered on July 25, 2025. Listen to the story here.

Coral reefs have been struggling as ocean waters are warming. They turn white as the algae inside them dies in the process known as bleaching. Now there are coral nurseries to help with their survival.

The Coral Restoration Foundation (CRF) operates a number of nurseries. Its Tavernier location covers an acre and a half of sea floor making it the largest in-situ facility of its kind. 

CRF developed what are called coral trees made from PVC pipe that support 20 different varieties of healthy pieces of coral. The corals get plenty of sun and clean flowing ocean water for the nutrients they need to grow.

This variety is important as different corals face different challenges. 

“We’re looking at a lot of local stressors,” said Roxane Boonstra, the Learning Ecosystems Administrator for CRF. “Local stressors are everything from agricultural runoff and overpollution and overfishing and direct damage. But then we’re really looking at the global climate stressors and this is going to take the shape of global warming and ocean acidification.” 

While coral reefs are beautiful to look at, they provide a number of other benefits. 

“Coral reefs cover less than 1% of the ocean floor but they support at least 25% of all marine species,” Boonstra said. 

They also mitigate storm damage by absorbing wave energy, in some cases by more than 90%. 

Former professor of Marine Science at the College of the Florida Keys, and author of Beneath the Blue Planet: A Diver’s Guide to the Ocean, Alex Brylske explained how corals grow and survive. And why they are in trouble today. 

“For hundreds of millions of years, these cnidarians have developed this relationship with algae that live inside them to provide the bulk of their nutrition, and they each assist each other,” he said. 

The two species are symbiotic. But, according to Brylske, they live and operate right at the edge of their tolerance. When things change, like the water heating up, that symbiotic relationship breaks down. 

There have been four global bleaching events on top of local events and estimates say corals in the Florida Keys are 97% to 98% degraded.

“You can always get back to, is something happening in the ocean itself, is something happening on the land or and the huge, encompassing problem now, of course, is something’s happening in the atmosphere,” Brylske said. “You get warming and the double whammy with climate change is excess CO2 in the ocean means it becomes more acidified.”

He referred to it as death by a thousand cuts. He said reefs could probably tolerate any of these insults individually, but not collectively.

Brylske said he had his doubts about coral nursery programs because of scalability. They just can’t keep up with the challenges. But he does see the value of programs like the one in Tavernier, however. 

“I’ve been involved with hundreds of students with them,” he said. “I’ve not seen anything that can be more impactful. Sometimes people come back in tears because they felt that they finally did something positive. And so they’re very, very impactful.”

But, he said, without stressing the need to stop climate change, they won’t make any difference. Some nursery programs are attempting to breed heat resistant corals. But the Coral Restoration Foundation takes a different approach. 

“The corals we’re working with are already the survivors of decades of local stress, a lot of different bleaching events, a lot of different stress events overall,” Boonstra said. “And so the corals we work with, they already are the tough ones.”

Once the corals hanging from the trees are big enough, and healthy enough, volunteers and members of the foundation’s team move them out onto the reef where they will continue to grow. 

Coral reefs aren’t just important for Florida residents, however. People from landlocked states need to pay attention as well.  

“Over 70% of the oxygen we breathe on a daily basis comes from our healthy ocean,” Boonstra said. “And coral reefs are a critical component of our healthy oceans.”