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Researchers have found that two of the primary coral species comprising Florida's reef are now functionally extinct following a intense ocean heatwave led to catastrophic losses.

The Meaning Behind 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once formed the foundation of reefs in Florida and the Caribbean, indicates they are no longer able to fulfill their previously crucial role in building and sustaining reef ecosystems that support a diversity of marine life.

Ecological extinction is a phase before global extinction, a threat that now hangs for many coral species.

Scientists this month alerted that a critical threshold has been crossed, meaning corals around the world are likely to be wiped out due to global heating, which is increasing ocean temperatures to unbearable levels.

Expert Insight

"We're running out of time," stated the lead author of the recent research. "Severe marine heatwaves are increasing in frequency and severity due to global warming, and absent swift, decisive measures to reduce ocean heating and boost coral resilience, we face the danger of the disappearance of additional coral species from reefs in Florida and around the world."

Details of the New Research

The new research, published in the Science journal, analyzed the outcome of staghorn coral and elkhorn coral corals off the Florida coast following a severe marine heatwave in 2023.

This event raised temperatures on Florida's deteriorating coral reefs to their highest levels in more than a century and a half.

The two species are complex, reef-building corals and are named because they resemble, respectively, the horns of stags and elks.

However, researchers who conducted underwater surveys of more than 52,000 colonies of the species, across 391 sites along Florida's coast, found widespread, often devastating, losses.

Regional Impact

• In the Florida Keys, mortality rates hit 98% and even 100%, showing a total eradication of the corals.
• In south-east Florida, where temperatures have been lower, death rates were lower, at about 38%.

Historical and Present Threats

The two Acropora species had already endured from decades of regional pressures in Florida, such as contaminated water from contaminants that wash off the land, as well as disease.

But the 2023 heatwave has been fatal for these temperature-sensitive species.

The 2023 heat event caused the ninth occurrence of coral bleaching on the Florida reef – a process whereby corals become thermally stressed and eject the algae partners living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals perish completely.

Global Implications

Globally, coral reefs are among the ecosystems most at risk to the anthropogenic climate crisis.

This presents a significant danger to:

• One-fourth of all ocean life that relies upon what are essentially the marine rainforests.
• Hundreds of millions of people who rely on corals to support fish that they can consume and gain an income from.

Corals also act as a protective barrier to safeguard our shorelines from powerful storms, which are themselves being worsened by increasing global heat.

Preservation Attempts

In a last-ditch effort to avert a decline of endangered corals, scientists have created repositories of Acropora in marine facilities and offshore coral nurseries.

Efforts have been made to replant corals on reefs in Florida, too, in an effort to restore some of the ninety percent of coral cover disappeared off the state in the last forty years.

But as global heating continues to escalate, there is little hope of long-term survival of these species without major interventions, scientists caution.

Additional Researcher Insight

"Elkhorn species, in particular, are some of the key wave-breaking coral species in the region," noted a study co-author, a ocean scientist at the University of Miami.

"They were once common on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, its worth taking exceptional steps to ensure we don't lose these corals altogether."