A Pair of Crucial Florida Coral Species Deemed 'Functionally Extinct' Following Devastating Ocean Heatwave

Scientists have discovered that two of the key coral species comprising Florida's reef are now ecologically extinct after a intense ocean heatwave caused catastrophic losses.

The Meaning Behind 'Functional Extinction' Signifies

The near-total decline of these corals, which once served as the foundation of reefs in Florida and the Caribbean, indicates they are no longer able to fulfill their once vital role in building and sustaining reef ecosystems that support a diversity of marine life.

Functional extinction is a phase before total extinction, a danger that now looms for many coral species.

Researchers recently alerted that a critical threshold had been reached, whereby corals globally are set to be eradicated due to climate change, which is increasing ocean temperatures to unbearable levels.

Expert Perspective

"Time is running out," stated the lead author of the recent research. "Extreme heatwaves are increasing in frequency and severity due to global warming, and absent swift, decisive measures to slow ocean warming and enhance coral survival, we risk the extinction of even more corals from reefs in Florida and worldwide."

Details of the New Research

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

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

The two species are intricate, reef-forming corals and are identified because they resemble, respectively, the horns of male deer and elks.

However, researchers who performed diver surveys of more than 52,000 colonies of the species, across nearly four hundred sites along Florida's coast, found extensive, often catastrophic, losses.

Geographic Impact

• Along the Florida Keys, death rates reached 98% and even 100%, revealing a complete annihilation of the corals.
• In southeastern Florida, where temperatures have been lower, death rates were lower, at about 38%.

Historical and Current Dangers

The two Acropora species had already suffered from decades of regional pressures in Florida, such as poor water quality from contaminants that wash off the land, as well as illness.

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

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

If temperatures remain elevated, the corals die off completely.

Worldwide Consequences

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

This poses a significant danger to:

• A quarter of all ocean life that depends on what are effectively the marine rainforests.
• Hundreds of millions of people who rely on corals to sustain fish that they can eat and gain an income from.

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

Preservation Efforts

In a last-ditch effort to avert a death spiral of threatened corals, scientists have created collections 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 regain some of the ninety percent of coral cover disappeared off the state in the past four decades.

But as climate change continues to intensify, there is little hope of continued existence of these species without major interventions, scientists caution.

Additional Researcher Insight

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

"They used to be common on shallow reef crests 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 preserve these corals altogether."