🔗 Share this article

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

The Meaning Behind 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once formed the foundation of reefs in Florida and the Caribbean, indicates they can no longer fulfill their previously crucial role in constructing and maintaining reef ecosystems that host a variety of marine life.

Functional extinction is a phase before total extinction, a danger that now looms for many coral species.

Researchers recently alerted that a tipping point has been crossed, meaning corals around the world are likely to be eradicated due to global heating, which is increasing ocean temperatures to intolerable levels.

Expert Insight

"We're running out of time," said Ross Cunning of the new Florida study. "Extreme heatwaves are becoming more frequent and intense due to global warming, and without swift, decisive measures to slow ocean warming and enhance coral survival, we face the danger of the extinction of additional coral species from reefs in Florida and worldwide."

Details of the Recent Study

The new research, published in the Science journal, analyzed the outcome of staghorn coral and elkhorn corals off the Florida coast following a intense marine heatwave in 2023.

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

The two species are complex, reef-forming corals and are named because they resemble, respectively, the horns 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 extensive, often devastating, losses.

Regional Effects

• In the Florida Keys, mortality rates hit 98% and even one hundred percent, revealing a total eradication of the corals.
• In southeastern Florida, where temperatures have been lower, mortality rates were lower, at about 38%.

Past and Present Threats

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

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

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

If temperatures remain elevated, the corals perish completely.

Worldwide Implications

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

This poses a significant danger to:

• One-fourth of all ocean life that relies upon what are effectively the rainforests of the sea.
• Millions of people who depend upon corals to sustain fish that they can eat and earn a livelihood from.

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

Conservation Attempts

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

Attempts have been made to reseed corals on reefs in Florida, too, in an effort to regain some of the ninety percent of coral cover lost 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 without significant actions, researchers warn.

Additional Expert Commentary

"Elkhorn species, in particular, are some of the key wave-breaking coral species in the area," noted a study co-author, 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 keep safeguarding our coastlines from inundation during storms, it is worthwhile taking extraordinary measures to ensure we preserve these corals altogether."