🔗 Share this article

Researchers have found that two of the most important coral species forming Florida's reef have become functionally extinct after a withering ocean heatwave led to catastrophic losses.

What 'Functional Extinction' Means

The near-total collapse of these corals, which once served as the foundation of reefs in Florida and the Caribbean, means they can no longer fulfill their once vital role in building and sustaining reef ecosystems that support a variety of marine life.

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

Scientists recently warned that a critical threshold had been reached, meaning corals globally are set to be wiped out due to global heating, which is increasing ocean temperatures to unbearable levels.

Researcher Insight

"We're running out of time," stated the lead author of the recent research. "Severe marine heatwaves are increasing in frequency and severity due to global warming, and absent swift, decisive measures to reduce ocean heating 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 Science journal, examined the outcome of staghorn coral and elkhorn corals off the Florida coast after a intense 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-building corals and are identified because they look like, respectively, the horns of stags and elk.

However, scientists who conducted underwater surveys of more than 52,000 colonies of the species, across nearly four hundred sites along Florida's coast, found widespread, often devastating, losses.

Geographic Impact

• In the Florida Keys, mortality rates hit ninety-eight percent and even one hundred percent, showing a complete annihilation of the corals.
• In southeastern Florida, where temperatures have been lower, mortality rates were reduced, at about 38%.

Past and Current Dangers

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

But the 2023 marine 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 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 entirely.

Global Implications

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

This presents a significant danger to:

• A quarter 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 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 prevent a decline of endangered corals, scientists have created collections of Acropora in marine facilities and offshore coral nurseries.

Efforts have been made to reseed corals on reefs in Florida, too, in an effort to restore some of the 90% of coral cover disappeared off the state in the last forty years.

But as climate change continues to intensify, there is little hope of continued existence of these species without major interventions, scientists caution.

Additional Expert Commentary

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

"They used to be abundant on shallow reef crests in the Caribbean, and if we want our reefs to continue protecting our coastlines from inundation during storms, its worth taking exceptional steps to ensure we don't lose these corals completely."