THE KEY WEST CITIZEN · SEPTEMBER 1, 2026
As Published in The Key West Citizen · September 2, 2026
The Florida Keys are experiencing another significant coral bleaching event. Heat stress arrived early and intensely this year, with elevated alert levels across the Florida Keys National Marine Sanctuary.
A Population in Crisis
Colonies that survived the 2023 bleaching event are once again under pressure. Some are expected to recover; others will not.
Selecting the Survivors
According to Mike Echevarria, president and co-founder of Reef Renewal USA, seawater temperatures have remained near or above NOAA’s bleaching threshold of 30.5°C (approximately 87°F) for at least a month.
We learned in the heat event of 2023 that the water was going to continue to get hotter. We have pivoted to identifying corals that have demonstrated thermal tolerance for the conditions of the future. We observed the winners in 2023 and have selected to focus on breeding and growing those corals. We are encouraged that our path forward is to identify or create the corals of the future using genetics and new spawning techniques and then grow them at an unprecedented scale.
Mike Echevarria, President & Co-Founder, Reef Renewal USA
Conditions vary by location. Middle and lower Keys reefs, along with inshore sites, are among the hottest due to the influence of warmer Florida Bay water. Upper Keys reefs from Key Largo northward have been somewhat buffered by the cooler Gulf Stream.
While reports of severe bleaching remain limited so far, continued stress is expected without cooling from tropical systems that bring wind, rain, and cloud cover.
A Record Spawning Season
We were really pleased with the results of the elkhorn coral spawn this year. A lot of people invested time and resources into coming down here to harvest and process these gametes and nobody left disappointed. I don’t know of an instance anywhere in Florida or the Caribbean where gametes from ten or more different genetic strains of elkhorn coral were collected in one night, and we were able to do it several nights. This kind of collaborative effort is what is going to be needed if we want to keep these endangered corals from going extinct. The energy on the boat after each of the big spawning nights was off the charts. I’m glad so many people were able to see the spawn and participate in collecting the gametes.
Ken Nedimyer, Technical Director, Reef Renewal USA
After the 2023 heat event, Florida’s wild elkhorn coral population declined sharply. Of the 158 unique genets known in the upper Keys before that summer, only about 23 remained in the wild. Mortality of elkhorn and staghorn was near 100 percent south of Molasses Reef off Key Largo, while colonies north of Molasses generally survived.
The Coral Restoration Consortium Genetics Working Group has stated that assisted gene flow should be implemented urgently, warning that waiting until populations decline further may close the window for intervention.
Restoration groups are now selecting surviving genotypes from 2023 and pairing them with more heat-tolerant colonies, including some from Honduras, to produce the next generation in laboratories before returning them to the reef.
These crossbred “Flonduran” offspring will not reverse ocean warming, but they represent one deliberate strategy to increase resilience.
Mote’s Emergency Rescue Operation
Our long-term investment in land-based coral restoration infrastructure allows us to respond quickly when ocean temperatures threaten our offshore nurseries. Protecting genetically diverse corals during these events is essential to advancing restoration science and ensuring we have resilient populations ready to return to Florida’s Coral Reef.
Dr. Michael P. Crosby, President & CEO, Mote Marine Laboratory
Every extreme heat event provides an opportunity to improve our understanding of coral resistance and resilience. By combining field observations with controlled research, we’re identifying the corals and restoration approaches that will be most successful as ocean conditions continue to change.
Dr. Jason Spadaro, Program Manager, Mote Coral Reef Restoration Research Program
That approach is already showing results. In the first week of August 2026, 12 organizations working under NOAA’s Re5 initiative collected millions of elkhorn and staghorn gametes from offshore nurseries operated by Reef Renewal USA and Mote Marine Laboratory near Key Largo. Scientists raced the spawn to a temporary lab at John Pennekamp Coral Reef State Park, made more than 100 directed genetic crosses, and produced more than 1.5 million embryos and more than 100,000 larvae.
Building Resilience, Buying Time
Storm surge and erosion are not theoretical in the Keys. These living shoreline projects — the wave attenuation devices, the native plantings — are practical tools that protect critical infrastructure while giving the natural system a chance to work with us instead of against us. We are buying time and building resilience at the same time.
Rhonda Haag, Former Monroe County Chief Resilience Officer; WSP USA Inc.
What Bleaching Is — and What Drives It
The Work Continues
The gametes were used for crossbreeding and cryopreservation. Partners will grow the larvae and, within about two years, return the new corals to nurseries and reef sites, including Mission: Iconic Reefs.
Mote Marine Laboratory has also launched a large-scale effort across the Keys to rescue thousands of vulnerable corals from its offshore nurseries before prolonged heat stress could prove fatal.
Photo Gallery
The Bleaching Event
The Spawn Collection Operation
Photos: Mike Echevarria / Reef Renewal USA · All rights reserved
The laboratory’s long-term investment in land-based coral restoration infrastructure has enabled the rapid response.
The rescue operation is generating new data as well. Mote scientists are evaluating how different coral genotypes resist and recover from prolonged heat stress.
Resilience is not a single trait. Some colonies host heat-tolerant symbiotic algae. Others recover more quickly after stress. Restoration teams are combining these advantages by selecting survivors, pairing them with more tolerant symbionts, and returning the next generation to the water.
The gains are real but modest. They buy time rather than eliminate the underlying heat stress.
Onshore, similar practical measures are underway. Wave Attenuation Devices are being installed at sites such as Long Key to reduce wave energy, protect infrastructure, and create conditions for seagrass and oysters to establish living shorelines.
Bleaching occurs when the partnership between the coral animal and the microscopic algae living in its tissues breaks down. Elevated seawater temperature is the dominant trigger. The rapid increase in mass bleaching events since the 1980s is driven primarily by human-caused climate change.
Local stressors such as nutrient pollution, sedimentation, overfishing, and coastal development do not cause the global bleaching pattern on their own, but they reduce resilience and slow recovery.
Restoration groups including the Coral Restoration Foundation, Mote Marine Laboratory, Reef Renewal USA, the Florida Aquarium, and others continue outplanting heat-selected and cross-bred colonies under programs such as Mission: Iconic Reefs.
Citizen efforts, including reef cleanups and Mote’s BleachWatch program (bleachwatch@mote.org), also contribute data and support.
The tools for response exist. The question is whether they continue to be used.
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