🔗 Share this article

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

The Meaning Behind 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once served as the backbone of reefs in Florida and the Caribbean, means they can no longer play their once vital role in constructing and maintaining reef ecosystems that support a variety of marine life.

Functional extinction is a stage before total extinction, a danger that now hangs for many coral species.

Researchers this month warned that a critical threshold had been reached, meaning corals around the world are likely to be eradicated due to global heating, which is raising ocean temperatures to unbearable levels.

Expert Perspective

"Time is running out," stated Ross Cunning of the recent research. "Extreme heatwaves are becoming more frequent and intense due to global warming, and absent immediate, ambitious actions to slow ocean warming and boost coral resilience, we face the danger of the extinction of even more corals from reefs in Florida and worldwide."

The New Research

The new research, published 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 elevated temperatures on Florida's deteriorating coral reefs to their highest levels in over 150 years.

The two species are complex, reef-building corals and are named because they resemble, respectively, the horns of male deer and elk.

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

Geographic Effects

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

Historical and Present Threats

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

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

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

If temperatures stay high, the corals die off entirely.

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 marine rainforests.
• Hundreds of millions of people who rely on corals to sustain fish that they can eat and gain an income from.

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

Preservation Efforts

In a last-ditch effort to prevent a death spiral of endangered corals, scientists have created repositories of Acropora in marine facilities and offshore coral nurseries.

Efforts have been made to replant corals on reefs in Florida, as well, in an effort to regain some of the 90% of coral cover disappeared off the state in the past four decades.

But as global heating continues to escalate, there is slim chance of continued existence of these species without major interventions, researchers warn.

Additional Researcher Insight

"Elkhorn species, in particular, are some of the most important wave-breaking coral species in the region," noted Andrew Baker, a marine biologist at the Miami University.

"They used to be common on shallow reef tops in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from flooding during storms, its worth taking exceptional steps to ensure we don't lose these corals altogether."