Critical Florida corals now ‘functionally extinct’ due to off-the-charts ocean temperatures

By_Suraj Karowa
October 28, 2025

Florida’s Iconic Corals Declared ‘Functionally Extinct’ After Record Ocean Heatwave

Florida’s once-vibrant coral reefs, long dominated by elkhorn and staghorn species that resembled underwater antler forests, have suffered a devastating blow. A new study published Thursday declares these critical corals “functionally extinct” in the region, following an extreme marine heatwave in 2023 that pushed ocean temperatures to unprecedented highs.

Led by the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Watch and Chicago’s Shedd Aquarium, the research tracked over 52,300 Acropora corals – encompassing elkhorn and staghorn varieties – across Florida’s 350-mile reef tract, from the Dry Tortugas and Florida Keys to the St. Lucie Inlet.

These corals, dominant reef builders for the past 10,000 years, were already listed as critically endangered due to diseases like stony coral tissue loss, pollution, hurricanes, and gradual ocean warming. But the 2023 summer heatwave proved catastrophic. Water temperatures soared above 90°F (32°C), marking the hottest recorded in at least 150 years, and persisted for about three months.

Corals under heat stress expel their symbiotic algae, which supply color and nutrients, resulting in bleaching. While short-term bleaching allows recovery if conditions normalize, prolonged exposure leads to starvation and death. Researchers documented rapid decline: By March 2024, 98% to 100% of colonies in the southern reef system were dead.

“Functional extinction” means surviving corals – mostly scattered in northern areas – exist in densities too low to fulfill their ecological role of constructing and maintaining reef structures, explained Ross Cunning, a Shedd Aquarium research biologist and study co-author.

The fallout is far-reaching. “Reef growth slows, habitat complexity declines, and fish and invertebrates lose shelter and resources,” Cunning told reporters. Coastal communities face heightened risks from storms and erosion without the natural barrier reefs provide.

Visual evidence is stark. Photos from June to September 2023 show vibrant elkhorn corals turning ghostly white and crumbling. Scientists like Gavin Wright from Shedd Aquarium sampled bleached sites, confirming widespread mortality.

This isn’t isolated to Florida. A University of Exeter study warns that global warm-water reefs have crossed a climate tipping point, with large-scale loss inevitable unless warming reverses. Projections indicate annual severe bleaching in Florida by 2040, potentially triggering “true global extinctions” of multiple Caribbean coral species decades ahead.
Natural recovery seems improbable.

Remaining corals remain susceptible to disease, predators, and storms. Efforts to intervene include nursery programs rearing corals onshore and offshore, but success hinges on reducing future heat events.

Keri O’Neil, director of the Coral Conservation Program at the Florida Aquarium (uninvolved in the study), called the findings “extremely significant.” She emphasized that functional extinction isn’t irreversible: “Human intervention, combined with improved ocean conditions, can reverse this trend.”
Cunning framed the report as an urgent call to action, not despair. “The window to prevent further losses is rapidly closing, yet targeted interventions and aggressive climate action can still make the difference,” he said.

The study underscores broader ocean warming trends driven by greenhouse gas emissions. Florida’s reefs, third-largest in the world, support a $8 billion tourism and fishing economy and protect against $1 billion in annual storm damage.

Experts urge immediate emission cuts, marine protected areas, and restoration funding. Without them, cascading losses could reshape marine ecosystems worldwide.