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Researchers have found that two of the primary coral species comprising Florida's reef are now ecologically extinct after a withering ocean heatwave caused devastating losses.

What 'Functional Extinction' Means

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

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

Researchers recently alerted that a tipping point has been crossed, meaning corals globally are likely to be wiped out due to climate change, which is increasing ocean temperatures to unbearable levels.

Researcher Perspective

"We're running out of time," stated Ross Cunning of the new Florida study. "Extreme heatwaves are increasing in frequency and severity due to global warming, and without immediate, ambitious actions to slow ocean warming and enhance coral survival, we risk the disappearance of even more corals from reefs in Florida and around the world."

Details of the New Research

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

This event elevated 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, in turn, the antlers of male deer and elk.

However, researchers who performed underwater surveys of over fifty-two thousand colonies of the species, across 391 sites along Florida's coast, found extensive, often devastating, losses.

Geographic Impact

• In the Florida Keys, mortality rates hit ninety-eight percent and even one hundred percent, showing a total eradication of the corals.
• In south-east Florida, where temperatures have been cooler, mortality rates were reduced, at about thirty-eight percent.

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 heatwave has been lethal for these heat-sensitive species.

The 2023 event caused the ninth episode of coral bleaching on the Florida reef – a phenomenon whereby corals become heat-stressed and expel the symbiotic algae living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals perish entirely.

Worldwide Consequences

Worldwide, coral reefs are among the ecosystems most vulnerable to the human-caused climate crisis.

This presents a significant danger to:

• One-fourth of all ocean life that depends on what are effectively the rainforests of the sea.
• Millions of people who depend upon corals to support fish that they can consume and earn a livelihood from.

Corals also serve as a protective barrier to protect our shorelines from powerful storms, which are themselves being worsened by rising global temperatures.

Preservation Efforts

In a desperate attempt to avert a decline of endangered corals, scientists have created collections of Acropora in aquariums and offshore coral nurseries.

Attempts have been undertaken to reseed corals on reefs in Florida, too, in an effort to regain some of the 90% of coral cover disappeared off the state in the last forty years.

But as global heating continues to intensify, there is slim chance of continued existence of these species absent major interventions, scientists caution.

Further Expert Commentary

"Elkhorn species, especially, are some of the most important wave-breaking coral species in the region," noted Andrew Baker, a ocean scientist at the University of Miami.

"They used to be common on shallow reef tops in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from flooding during storms, its worth taking exceptional steps to ensure we preserve these corals altogether."