A Pair of Essential Florida Coral Species Declared 'Functionally Extinct' Following Severe Ocean Heatwave

Scientists have discovered that two of the key coral species forming Florida's reef are now ecologically extinct following a intense ocean heatwave caused devastating losses.

The Meaning Behind 'Functional Extinction' Signifies

The near-total collapse of these corals, which once formed 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 host a variety of marine life.

Ecological extinction is a phase preceding global extinction, a threat that now hangs for many coral species.

Scientists this month alerted that a tipping point has been crossed, meaning corals globally are likely to be wiped out due to climate change, which is raising ocean temperatures to intolerable levels.

Expert Insight

"Time is running out," stated Ross Cunning of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to climate change, and absent swift, decisive measures to slow ocean warming and boost coral resilience, we risk the disappearance of even more corals from reefs in Florida and worldwide."

Details of the New Research

The recent study, published in the Science journal, examined the outcome of staghorn coral and elkhorn corals off the Florida coast after a severe marine heatwave in 2023.

This event elevated temperatures on Florida's fraying coral reefs to their highest levels in over 150 years.

The two species are complex, reef-forming corals and are identified because they resemble, in turn, the horns of stags and elks.

However, researchers who performed diver surveys of over fifty-two thousand colonies of the species, across 391 sites along Florida's coast, found extensive, often devastating, losses.

Geographic Effects

• In the Florida Keys, death rates reached ninety-eight percent and even one hundred percent, revealing a total eradication of the corals.
• In southeastern Florida, where temperatures have been lower, death rates were lower, at about thirty-eight percent.

Past and Present Threats

The two Acropora species had already endured from decades of regional pressures in Florida, such as poor water quality from contaminants 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 bleaching on the Florida reef – a phenomenon whereby corals become thermally 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.

Worldwide Implications

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

This poses a major threat to:

• A quarter of all ocean life that depends on what are essentially 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 safeguard our shorelines from intense hurricanes, which are themselves being worsened by rising global temperatures.

Preservation Efforts

In a last-ditch effort to avert a decline of endangered corals, scientists have created repositories of Acropora in marine facilities and ocean-based nurseries.

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

But as climate change continues to escalate, there is little hope of long-term survival of these species absent major interventions, scientists caution.

Further Researcher Insight

"Elkhorn species, especially, are some of the key wave-dampening coral species in the area," noted Andrew Baker, a ocean scientist at the University of Miami.

"They were once abundant on shallow reef crests in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, its worth taking extraordinary measures to ensure we don't lose these corals altogether."