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

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once formed the foundation of reefs in Florida and the Caribbean, means they can no longer play their once vital role in building and sustaining reef ecosystems that support a variety of marine life.

Functional extinction is a stage preceding global extinction, a danger that now looms for many coral species.

Researchers this month warned that a tipping point has been crossed, meaning corals globally are likely to be eradicated due to climate change, which is increasing ocean temperatures to unbearable levels.

Researcher Insight

"We're running out of time," stated the lead author of the new Florida study. "Extreme heatwaves are increasing in frequency and severity due to climate change, 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 recent study, published in the journal Science, examined the outcome of staghorn and elkhorn coral corals off the Florida coast following a intense marine heatwave in 2023.

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

The two species are intricate, reef-forming corals and are named because they resemble, in turn, the antlers of stags and elk.

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

Regional Impact

• Along the Florida Keys, death rates reached 98% and even one hundred percent, showing a total eradication of the corals.
• In south-east Florida, where temperatures have been lower, mortality rates were reduced, at about thirty-eight percent.

Past and Current Dangers

The two Acropora species had already suffered from many years of localized impacts in Florida, such as poor water quality from contaminants that wash off the land, as well as illness.

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

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

If temperatures stay high, the corals die off completely.

Worldwide Implications

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 rainforests of the sea.
• 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 protect our shorelines from powerful storms, which are themselves being intensified by rising global temperatures.

Conservation Efforts

In a last-ditch effort to prevent a decline of endangered corals, scientists have created repositories of Acropora in aquariums and ocean-based nurseries.

Attempts have been undertaken to reseed corals on reefs in Florida, as well, in an effort to restore some of the 90% of coral cover lost off the state in the past four decades.

But as climate change continues to escalate, there is slim chance of continued existence of these species without significant actions, researchers warn.

Further Expert Commentary

"Elkhorn species, especially, are some of the key wave-dampening coral species in the area," noted Andrew Baker, a marine biologist at the Miami University.

"They used to be common on shallow reef crests in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from inundation during storms, its worth taking extraordinary measures to ensure we don't lose these corals altogether."