Coral IVF: Inside Miami’s Race to Rebuild Florida’s Reefs Before the Next Heat Wave Hits
I lived on the East Coast for many years, so Florida, specifically the Keys, was a popular vacation spot for my family. One of my favorite memories was snorkeling with my younger sister. In 1996, snorkeling in Key West was a special experience because it was before the major bleaching events. The shallow reefs were completely intact, covered in beautiful branching corals and packed with marine life. However, many things have changed since then.
On a Wednesday morning in July 2026, divers from the University of Miami’s Rosenstiel School worked on a stretch of reef off Key Biscayne, wrapping pieces of elkhorn coral in wet bubble wrap and loading them into coolers. By afternoon, the coral were in tanks on dry land, sanitized, and settled into a saltwater hatchery. Nobody called it an emergency, at least not yet.
“This is us being proactive,” senior research associate Dalton Hesley told the Associated Press1. The urgency was real as water temperatures were already running hotter than they had in 2023, the year a marine heatwave wiped out nearly every elkhorn and staghorn coral colony in the Florida Keys.
A single afternoon of coral-moving was one small piece of a greater effort underway in South Florida, where scientists have spent the past three years trying to do something that sounds almost too simple to work: help coral have babies.
A Reef Nearly Wiped Out
Coral IVF became one of the state’s most closely watched restoration tools because the last few years were so bad. In the summer of 2023, an El Niño-driven marine heatwave pushed South Florida’s water temperatures to the highest levels in more than 150 years. Coral is highly sensitive to heat. When it is under thermal stress, it expels the algae living in its tissue that give it color and food, a process called bleaching. When the stress lasts too long, the coral starves.
A team from the University of Miami surveyed 52,000 coral colonies across 391 sites to measure the damage. Their findings, published through the Rosenstiel School2 in October 2025, were bleak: the elkhorn and staghorn coral mortality rates in the Florida Keys and Dry Tortugas were 98% to 100%. Even in the cooler waters of southeast Florida, they still lost close to 38%. The two species, the primary reef builders in the Caribbean, were formally declared “functionally extinct” in Florida waters, which means surviving colonies could no longer reproduce on their own.
“Elkhorn corals are some of the most important wave-breaking coral species in the region,” said Andrew Baker, director of the University of Miami’s Coral Reef Futures Lab, in the same university report. Lose that structure, and a reef loses much of its ability to blunt incoming waves before they reach shore.
What Coral IVF Actually Means
Coral doesn’t reproduce the way most people think. Once a year, on a handful of nights tied to the lunar cycle, healthy colonies release bundles of eggs and sperm into the water all at once, an event scientists call mass spawning. In the wild, most of that genetic material drifts away and never finds a match.
However, Coral IVF intercepts it. Researchers with the University of Miami and Nova Southeastern University collected the egg-and-sperm bundles during spawning, fertilized them in controlled conditions, and raised the resulting larvae in nurseries before eventually transplanting the young coral back onto damaged reefs.
“We raise them for a year and a half,” Rachel Ionata, a research manager with the program, told CBS News Miami3. “We feed them and do everything in stages.” Juvenile coral is kept in protective cages at first, to shield it from predatory fish before it’s strong enough for open reef.
The payoff isn’t just more coral. It’s more genetically diverse coral. Much of Florida’s existing reef was rebuilt over the past two decades by fragmenting and replanting a relatively small number of surviving colonies, which is fast but produces genetic clones. Assisted reproduction crosses different parent colonies instead, the way sexual reproduction works in any species. That matters when the goal is finding offspring that can tolerate heat, disease, or acidification their parents couldn’t.
Early Signs of Success
This is not a new concept. University of Miami researchers first documented restored, nursery-grown coral spawning on its own in the wild4 back in 2020, a proof of concept for the whole approach. The strongest evidence yet came out of the very disaster the program was built to survive.
SECORE International, a restoration nonprofit, ran a study about lab-bred juvenile coral raised through assisted reproduction. They tracked them at five sites across the Caribbean, from Curaçao to the U.S. Virgin Islands. In September 2024, WUSF reported 5 on the findings: the IVF-raised juveniles survived the brutal 2023–24 bleaching event far better than wild coral the same age growing nearby. Adults died by the tens of thousands that year, but the Caribbean’s coral hadn’t lost its ability to produce offspring tough enough to handle the heat.
Scaling Up Fast
Proof of concept was one thing. Rebuilding a reef tract was another, and it required money and coordination on a different scale entirely. In November 2024, NOAA awarded a four-year, $16 million grant to the University of Miami’s Rosenstiel School, which led an eleven-organization coalition that included Nova Southeastern University, Mote Marine Laboratory, the Florida Aquarium, SECORE International, Reef Renewal USA, and the Smithsonian Marine Station, among others, according to NOAA Fisheries6.
The grant funded several strategies running alongside coral IVF: propagating coral that survived in 2023 to preserve whatever heat tolerance it already carried, thermally conditioning young coral before it was ever exposed to open water, and pairing larvae with heat-adapted algae and probiotic bacteria. One notable offshoot: in July 2025, University of Miami researchers, the Florida Aquarium, and the Honduras-based nonprofit Tela Marine outplanted the first internationally crossbred elkhorn coral onto a wild reef off Miami, a hybrid of one Florida parent and one Honduran parent. The Honduran parent came from a reef that already tolerated water roughly 2°C (35.6°F) warmer than Florida’s, according to Axios Miami7.
In June 2026, the university expanded a related project called ECoREEF off Miami Beach, attaching 205 coral colonies across seven native species, plus thousands of coral larvae, to newly installed, 3D-printed reef structures about 750 feet offshore. “The ECoREEF structures are a great opportunity to develop and test new approaches to producing the kinds of hardy corals we need to restore reefs in the 21st century,” Baker said, per the Rosenstiel School8. NOAA set an overall target for the program, dubbed Mission: Iconic Reefs, of raising coral cover at seven key Florida Keys sites from roughly 2% to 25%.
Racing 2026
All of it brought the story back to that July morning off Key Biscayne. Diego Lirman, an associate professor of marine biology at the Rosenstiel School and founder of its Rescue a Reef program, had watched four mass bleaching events hit Florida coral in the past decade. What worried him about 2026 wasn’t just the heat. It was the timing.
“They seem to be blending into each other, and corals are not getting time to recover,” Lirman told the Associated Press1. He and his team believed 2026 could rival, or exceed, 2023.
By late July, South Florida sat at bleaching Alert Level 1 and the Florida Keys at Level 2, with water temperatures already outpacing 2023 at the same point in the season. NOAA coral ecologist Ian Enochs put it plainly to the Miami Herald9: “Visible coral stress this early in the summer season does not bode well for the health of our reefs.”
“You never know: You may have some that are resistant to disease, some that are resistant to temperature, some that are resistant to acidification,” Lirman said. “Once we lose them, then that information is lost.” Rather than wait for another full-scale emergency, teams moved coral preemptively, some to deeper, cooler water and some into onshore tanks, while continuing to exchange coral fragments between nurseries and hatcheries around the state. It amounted to a kind of distributed insurance policy.
Why It Matters From the Water
For anyone who spends time on a boat in South Florida, this is not an abstract science story. Healthy reef structure is what breaks up incoming wave energy before it reaches the beach or the marina. That’s why Baker singled out the loss of elkhorn coral as such a structural problem. Reefs are also the backbone of the fishing and diving economy that a lot of boaters build their weekends, and their livelihoods, around. None of that runs on wishful thinking. It runs on whether enough coral survives the next heat spike to keep building reef faster than the ocean tears it down.
That was the bet coral IVF made, not that scientists could out-plant their way past climate change, but that enough genetically varied, lab-raised coral on the reef would give some fraction of it the traits needed to survive what was coming. Nobody involved called it a guaranteed fix. Lirman described it, more modestly, as trying to “slow down the decline” while giving reefs “a push” toward recovery.
I still think about that reef off Key West, the one my sister and I swam over in 1996. It won’t come back looking exactly like it did that summer. But if enough of these lab-raised corals take, there might be something worth swimming out to again, and something worth handing off to whoever’s kid sister gets there next.
Sources
1. Marta Lavandier and Tammy Webber, “Florida researchers bring endangered elkhorn coral ashore to protect them,” Associated Press, July 22, 2026. https://apnews.com/article/coral-rescue-florida-330525586a3c0811cf4e8961929dd88c
2. “New Study Documents Functional Extinction of Two Critically Endangered Coral Species Following Record Heatwave in Florida,” University of Miami Rosenstiel School, October 2025. https://news.miami.edu/rosenstiel/stories/2025/10/new-study-documents-functional-extinction-of-two-critically-endangered-coral-species-following-record-heatwave-in-florida.html
3. “South Florida marine scientists use ‘coral IVF’ method to restore damaged reef systems in the Keys,” CBS News Miami. https://www.cbsnews.com/miami/news/coral-ivf-restoration-system-key-west-university-of-miami-nova-southeastern-university/
4. “Restored Corals Observed Spawning for First Time in Waters off Miami,” University of Miami Rosenstiel School, August 2020. https://news.miami.edu/rsmas/stories/2020/08/restored-corals-observed-spawning-for-first-time-in-waters-off-miami.html
5. “IVF-like breeding helps corals conceive hardy babies, rebuilding reefs,” WUSF, September 23, 2024. https://www.wusf.org/environment/2024-09-23/ivf-like-breeding-helps-corals-conceive-hardy-babies-rebuilding-reefs
6. “NOAA and Partners Launch Next-Generation Coral Restoration Following Florida Coral Bleaching,” NOAA Fisheries. https://www.fisheries.noaa.gov/feature-story/noaa-and-partners-launch-next-generation-coral-restoration-following-florida-coral
7. “University of Miami team helping to save Florida’s coral reefs,” Axios Miami, July 17, 2024. https://www.axios.com/local/miami/2024/07/17/new-research-to-save-floridas-coral-reefs
8. “University of Miami Researchers and Collaborators Expand Hybrid Reef Project off Miami Beach,” University of Miami Rosenstiel School, June 2026. https://news.miami.edu/rosenstiel/stories/2026/06/university-of-miami-researchers-and-collaborators-expand-hybrid-reef-project-off-miami-beach.html
9. Alex Harris, “Coral rescue efforts ramp up in Miami as researchers fear another deadly hot year,” Miami Herald, July 23, 2026 (via The Spokesman-Review). https://www.spokesman.com/stories/2026/jul/23/coral-rescue-efforts-ramp-up-in-miami-as-researche/
