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Researchers have found that two of the most important coral species comprising Florida's reef have become ecologically extinct following a intense ocean heatwave caused devastating losses.

What 'Functional Extinction' Means

The almost complete collapse of these corals, which once served as the backbone of reefs in Florida and the Caribbean, means they are no longer able to play 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 recently alerted that a tipping point has been crossed, meaning corals around the world are set to be wiped out due to climate change, which is raising ocean temperatures to unbearable levels.

Expert Insight

"We're running out of time," stated Ross Cunning of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to global warming, and absent immediate, ambitious actions to slow ocean warming and enhance coral survival, we face the danger of the disappearance of even more corals from reefs in Florida and worldwide."

Details of the Recent Study

The recent study, featured in the journal Science, examined the fate of staghorn and elkhorn coral corals off the Florida coast after 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 intricate, reef-forming corals and are named because they look like, respectively, the horns of male deer and elk.

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

Regional Impact

• In the Florida Keys, death rates hit ninety-eight percent and even 100%, revealing a total eradication of the corals.
• In south-east Florida, where temperatures have been cooler, death rates were reduced, at about 38%.

Historical and Current Dangers

The two Acropora species had already endured from many years of regional pressures in Florida, such as poor water quality from pollutants that wash off the land, as well as illness.

But the 2023 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 heat-stressed and expel the symbiotic algae living in their tissues, causing them to become ghostly white.

If temperatures remain elevated, the corals die off entirely.

Worldwide Consequences

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

This poses a major threat to:

• One-fourth of all ocean life that depends on what are effectively the rainforests of the sea.
• Hundreds of millions of people who rely on corals to sustain fish that they can consume and earn a livelihood from.

Corals also act as a barrier to protect our shorelines from intense hurricanes, which are themselves being worsened by increasing global heat.

Preservation Efforts

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

Attempts have been undertaken to reseed corals on reefs in Florida, as well, 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 escalate, there is slim chance of long-term survival of these species absent significant actions, scientists caution.

Further Expert Commentary

"Elkhorn corals, in particular, are some of the key wave-breaking coral species in the region," noted Andrew Baker, a marine biologist at the University of Miami.

"They used to be abundant on shallow reef crests in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, it is worthwhile taking extraordinary measures to ensure we preserve these corals altogether."