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

What 'Functional Extinction' Signifies

The near-total decline of these corals, which once formed the backbone of reefs in Florida and the Caribbean, means they are no longer able to fulfill their previously crucial role in building and sustaining reef ecosystems that host a variety of marine life.

Ecological extinction is a phase before total extinction, a danger that now hangs for many coral species.

Scientists this month warned that a tipping point had been reached, whereby corals globally are set to be wiped out due to climate change, which is increasing ocean temperatures to unbearable levels.

Researcher Insight

"We're running out of time," said the lead author of the new Florida study. "Extreme heatwaves are increasing in frequency and severity due to climate change, and without immediate, ambitious actions to slow ocean warming and boost coral resilience, we risk the extinction of even more corals from reefs in Florida and worldwide."

Details of the Recent Study

The recent study, published in the journal Science, analyzed the outcome of staghorn and elkhorn coral corals off the Florida coast following 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 complex, reef-forming corals and are named because they resemble, in turn, the antlers of male deer and elks.

However, researchers who performed diver surveys of over fifty-two thousand colonies of the species, across nearly four hundred sites along Florida's coast, found extensive, often catastrophic, losses.

Regional Impact

• Along the Florida Keys, mortality rates hit 98% and even 100%, showing a complete annihilation of the corals.
• In southeastern Florida, where temperatures have been cooler, mortality rates were lower, at about thirty-eight percent.

Past and Current Dangers

The two Acropora species had already endured from decades of regional pressures in Florida, such as contaminated water from contaminants that wash off the land, as well as disease.

But the 2023 heatwave has proved lethal for these temperature-sensitive species.

The 2023 heat event caused the ninth episode of bleaching on the Florida reef – a process 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 Consequences

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

This poses a significant danger to:

• A quarter of all ocean life that relies upon what are essentially the marine rainforests.
• Millions of people who rely on corals to sustain fish that they can consume and gain an income from.

Corals also act as a protective barrier to protect our shorelines from powerful storms, which are themselves being intensified by increasing global heat.

Preservation Efforts

In a last-ditch effort to avert a death spiral of threatened corals, scientists have established repositories of Acropora in aquariums and ocean-based nurseries.

Attempts have been made to replant corals on reefs in Florida, too, in an effort to restore 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 little hope of long-term survival of these species without significant actions, scientists caution.

Further Expert Commentary

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

"They used to be abundant on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, it is worthwhile taking exceptional steps to ensure we don't lose these corals altogether."