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Scientists have discovered that two of the key coral species comprising Florida's reef have become ecologically extinct following a withering ocean heatwave caused catastrophic losses.

What 'Functional Extinction' Signifies

The near-total collapse of these corals, which once served as the backbone of reefs in Florida and the Caribbean, means they can no longer fulfill their previously crucial 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 had been reached, whereby corals globally are likely to be wiped out due to climate change, which is increasing ocean temperatures to intolerable levels.

Expert Insight

"Time is running out," stated the lead author of the recent research. "Severe marine heatwaves are increasing in frequency and severity due to climate change, and without immediate, ambitious actions to slow ocean warming and enhance coral survival, we risk the extinction of additional coral species from reefs in Florida and around the world."

Details of the Recent Study

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

This event raised 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-building corals and are named because they look like, in turn, the antlers of stags and elk.

However, scientists who conducted diver surveys of over fifty-two thousand colonies of the species, across 391 sites along Florida's coast, found widespread, often catastrophic, losses.

Geographic Impact

• Along the Florida Keys, death rates hit ninety-eight percent and even one hundred percent, revealing a total eradication of the corals.
• In south-east Florida, where temperatures have been lower, death 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 run 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 coral bleaching on the Florida reef – a process whereby corals become heat-stressed and eject the symbiotic algae living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals die off completely.

Global Consequences

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

This poses a major threat to:

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

Corals also serve as a barrier to safeguard our shorelines from intense hurricanes, which are themselves being intensified by rising global temperatures.

Preservation Attempts

In a last-ditch effort to avert a death spiral of threatened corals, scientists have established collections of Acropora in marine facilities and offshore coral nurseries.

Efforts have been undertaken to reseed corals on reefs in Florida, as well, in an effort to regain some of the 90% of coral cover lost off the state in the last forty years.

But as climate change continues to intensify, there is slim chance of long-term survival of these species absent major interventions, scientists caution.

Additional Researcher Insight

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

"They were once common on shallow reef crests in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from inundation during storms, it is worthwhile taking exceptional steps to ensure we preserve these corals altogether."