The Incredible Importance of Restoring Coral

Coral reefs are in dire straits worldwide and in Florida.

Globally, coral reefs have been reduced by 50 percent. In Florida, where the third largest barrier reef in the world stretches about 350 miles down the east coast, only 2 percent of its living coral cover remains. The reef extends from the Dry Tortugas to the St. Lucie Inlet.

Reasons for coral loss are stressors such as climate change, marine heat waves like last summer’s extreme ocean temperatures, acidification of oceans, disease, overfishing, pollution, hurricanes and other factors.

Coral reefs are often called the “rainforests of the sea” because of the diversity of life found in the habitats created by corals, according to NOAA. About 25 percent of the ocean’s fish depend on healthy coral reefs.

“We’ve been tracking a kind of a degradation of corALEX al reefs across the entire globe for the better part of a century now,” said Jason Spadaro, staff scientist and program manager for the Florida Coral Reef Restoration Program at Mote Marine Laboratory & Aquarium. But that degradation has been accelerating in the last few decades.

A specimen of brain coral is removed from Honduran waters by a diver from the University of Miami Coral Reef Futures Lab. WEN /COURTESY UNIVERSITY OF MIAMI ROSENSTIEL SCHOOL

“And it’s important to note that those stresses aren’t one plus one equals two. They’re synergistic,” Spadaro said. They exacerbate the effects of one another, he said. “So it’s one plus one equals five.”

The result is coral bleaching events that records indicate have become more frequent and severe since the 1980s. Bleaching is the loss of corals’ symbiotic algae, which provides their color. The algae provide food for the coral. “So, if you lose all those algae, they have to either eat a lot more, or they starve,” Spadaro said.

A record-breaking heat wave in summer 2023 caused widespread bleaching of coral in the Florida Keys.

“They’re definitely the foundation of that entire ecosystem,” Spadaro said. “Without corals, you wouldn’t have the reef that supports all of these other non-coral species that are important ecologically, economically and socially.”

SPADARO

Economically, corals have an estimated $8 billion value through fishing, thousands of jobs, tourism and recreation.

The first thing to understand about coral is that it is an animal, not a plant. Spadaro said many people not familiar with coral are surprised to hear that.

They house a symbiotic algae that photosynthesizes. Then, they deposit mineral skeletons underneath them, which is the basis for coral reefs. So “they’re animal, mineral and vegetable all kind of in one very exciting package,” he said. Some species of corals have tiny, tentacle-like arms that they use to capture their food and sweep it into their mouths.

There are about 64 species of coral in the Caribbean and Florida. Globally, there are about 900 species, Spadaro said.

All of the species of coral in Florida are under threat, particularly the endangered elkhorn and staghorn corals, he said.

A staff member cares for baby coral colonies growing in the Mote Marine land nursery. MOTE MARINE / COURTESY PHOTO

“But they’re also this canary in the coal mine,” Spadaro said. “So coral reefs don’t necessarily produce a large proportion of the oxygen that we’re breathing, but our open ocean ecosystems do. A vast majority of the oxygen that we’re breathing is produced by algae in the sea. And a healthy, open ocean ecosystem is absolutely critical to life on Earth. And if our coral reefs are showing this decline, that’s a sign that we need to pay attention to the health of our oceans as a whole.”

This is why scientists and researchers at several facilities throughout Florida are working hard to stem the tide of loss, including Mote Marine, based in Sarasota, with eight campuses around Florida, and other sites like The Florida Aquarium, working with the University of Miami on a project to bring coral back from Honduras to see if cross breeding can boost the resilience of Florida coral.

Mote Marine’s approach is to:

• Promote coral sexual reproduction (spawning, fertilization and settlement).

Jason Spadaro, program manager for the Florida Coral Reef Restoration Program at Mote Marine Laboratory & Aquarium, checks on corals growing in Mote’s offshore nursery. MOTE MARINE / COURTESY PHOTO

• Grow corals from microscopic larvae to adult colonies.

• Test coral genetic varieties for resilience to stressors like climate change and disease.

• Produce more colonies through fragmenting corals asexually.

• Plant corals onto damaged reefs.

• Raise corals to maturity to start the process again.

Mote Marine is cloning corals, growing corals, providing assisted sexual reproduction and trying to cross breed for selective traits and creating diverse genetic varieties that will be more resilient to the stresses corals are enduring. Corals are grown in land nurseries, transferred to offshore nurseries and eventually planted carefully to replace coral that has been lost.

That’s a highly abbreviated and simplified version of a process that is as fascinating as it is complex, labor intensive and delicate.

The efforts are based at Mote’s Elizabeth Moore International Center for Coral Reef Research & Restoration on Summerland Key.

Keri O’Neil, director of The Florida Aquarium, examines a specimen of elkhorn coral brought from Honduras in the aquarium’s land nursery. THE FLORIDA AQUARIUM / COURTESY PHOTO

“Restoration is probably not the right term for what we’re doing,” Spadaro said. “It’s probably remediation or rehabilitation. Because we’re not trying to put all the corals that were there back. We’re trying to put enough colonies of spawning size close enough together so that natural recovery processes take over.”

“Not only do we have to put corals back onto the reef, but we have to select for traits that are resilient to the current stresses and the ones that’ll be there 50 or 100 years down the road,” he said. “So, it’s not just a matter of taking a bunch of coral, making a bunch of pieces and then putting them back onto the reef. We have to be very careful about which corals we’re putting back, and in which different proportions and which species we’re combining with one another.”

“The goal is building a community that can withstand the insults that they’re getting right now and the ones that we anticipate and the ones that we can’t,” Spadaro said.

In another effort to bring diversity and resilience to coral communities, The Florida Aquarium has been working on a partnership with the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science to bring corals, particularly endangered elkhorn corals, from Honduras to the United States.

“This is the first time living elkhorn coral colonies have been transported across international lines with the hope of cross-breeding them for restoration,” said Keri O’Neil, director and senior scientist at The Florida Aquarium.

The project is spearheaded by Andrew Baker, professor of marine biology and ecology and director of the Coral Reef Futures Lab at the Rosenstiel School. “We work with Dr. Baker’s lab on many different coral projects and coral spawning projects,” O’Neil said. “They really entrusted us to take half of these elkhorn corals, because they know our previous success with coral spawning work and being able to successfully raise the offspring.”

Diver Cailyn Joseph from the University of Miami Coral Reef Futures Lab sorts coral on the sea floor off the coast of Honduras. UNIVERSITY OF MIAMI ROSENSTIEL SCHOOL / COURTESY PHOTO

The coral went through a 15-hour journey by land, sea and air to get to Miami and the aquarium’s Coral Conservation and Research Center in Apollo Beach.

Due to last summer’s heat wave, “we lost a significant amount of elkhorn coral on Florida’s coral reef,” O’Neil said. The water got up to the low 90s, and it was too high for most of them to survive, she said. However, the elkhorn corals from Honduras live in a bay where the water temperature pretty routinely gets to 90 degrees in the summer. “So, we hope that they are adapted to those conditions. If we breed them, they may transfer some heat tolerance genetically into the Florida population.” Since the elkhorn are not reproducing successfully in the wild, they will try to reproduce them in the lab so that they have a chance of recovery, she said.

Coral only spawns once a year, on cues from the lunar cycle and the water temperature, according to NOAA. This means entire colonies of coral reefs simultaneously release their tiny eggs and sperm into the ocean.

Spadaro tried to give a layman’s version of the intricate process. “They spit a packet that is eggs wrapped in a sheath of sperm,” Spadaro said. They’re tiny, like little pins with the round top on them, he said. “And they’ll let bunches of them go at the same time.” When the little bubbles hit the surface, waves will move them around, and they’ll break, he said. That disperses the sperm into a slick, and then the eggs mix in.

In the land nursery, Mote will have individual colonies of known genotypes where scientists know the resilience traits located in different tanks, he said. “And we’ll have eggs and sperm released from each of them, and we’ll grab the eggs and sperm from this one and the eggs and sperm from this one.” Then, “you do intentional crosses of different individuals so that you have selective breeding, essentially.” Then coral babies can develop.

At The Florida Aquarium, the elkhorn corals from Honduras are placed into the aquarium system designed to promote coral spawning by mimicking environmental cues such as sunrise and sunset, moon cycles and seasonal temperature changes. “It’s all controlled by a computer and LED lighting,” O’Neil said.

They need the Honduran and Florida corals to spawn on the same day, she said. “And then what we do is we collect their egg and sperm bundles from the aquarium, and then we do the crossing. We do basically assisted fertilization, where we’ll take the eggs from one and mix them with the sperm from another and cross them in the laboratory and raise the larvae in our lab.”

However, if the Florida coral spawns before the Honduran coral or vice versa, they have a cryopreservation lab that freezes the sperm at a very low temperature, she said. “They’re actually still viable when they’re thawed and can be used to fertilize the eggs.”

There is clearly progress being made. Mote Marine scientists have restored 230,000 to 240,000 to Florida’s coral reef over the last several years, most of them since about 2016, Spadaro said. Several of the restored corals have spawned, engaging in sexual reproduction to produce new corals.

The Florida Aquarium’s Coral Conservation Program is also among the leaders in coral restoration. To date, biologists have successfully spawned 14 different species of coral at The Florida Aquarium — many of which had never reproduced in a lab before.

Spadaro has hope for the future. “It’s really easy to kind of look at all the negative and forget that this isn’t the first heat wave that they’ve gone through. This isn’t the worst stress that they’ve gone through. This is just another in a long history of insults against coral reefs. And if it’s not a heat wave, it’s a disease. If it’s not a disease, it’s overfishing or pollution or endocrine disruptors in the water.”

These are all challenges that have solutions, Spadaro said. “And the biggest kind of bright spot in all of this is that Florida’s coral reef has survived all of these things. It’s obviously down, but it’s not out,” he said.

“This isn’t the end of coral reefs in Florida. We get up every day and we come in and we have faith. We don’t even need to have faith. We have science that shows us that, yes, we can do this. This is a solvable problem.”

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