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

The Meaning Behind 'Functional Extinction' Signifies

The near-total decline of these corals, which once formed the foundation 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 support a variety of marine life.

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

Scientists this month alerted that a tipping point has been crossed, whereby corals around the world are likely to be eradicated due to climate change, which is increasing ocean temperatures to unbearable levels.

Expert Insight

"We're running out of time," said the lead author of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to global warming, and without immediate, ambitious actions to reduce ocean heating and boost coral resilience, we risk the extinction of even more corals from reefs in Florida and around the world."

The New Research

The new research, featured in the journal Science, analyzed the outcome of staghorn coral 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 peak temperatures in over 150 years.

The two species are intricate, reef-building corals and are named because they look like, respectively, the horns of stags and elks.

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

Regional Impact

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

Historical and Current Dangers

The two Acropora species had already endured from many years of regional pressures in Florida, such as contaminated water from pollutants that run off the land, as well as disease.

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

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

If temperatures remain elevated, the corals perish completely.

Global Consequences

Globally, coral reefs are among the ecosystems most at risk to the human-caused climate emergency.

This presents a major threat to:

• One-fourth of all ocean life that relies upon what are essentially the rainforests of the sea.
• Hundreds of millions of people who depend upon corals to sustain fish that they can eat and gain an income from.

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

Preservation Efforts

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

Efforts have been made to replant corals on reefs in Florida, too, in an effort to restore some of the ninety percent of coral cover disappeared off the state in the last forty years.

But as global heating continues to escalate, there is little hope of continued existence of these species without significant actions, scientists caution.

Additional Researcher Insight

"Elkhorn corals, especially, are some of the most important wave-dampening coral species in the region," said a study co-author, a ocean scientist at the University of Miami.

"They used to be abundant on shallow reef tops in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from flooding during storms, it is worthwhile taking extraordinary measures to ensure we don't lose these corals completely."