🔗 Share this article

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

The Meaning Behind 'Functional Extinction' Means

The almost complete collapse of these corals, which once formed the backbone of reefs in Florida and the Caribbean, means they can no longer fulfill their once vital role in building and sustaining reef ecosystems that host a diversity of marine life.

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

Researchers this month warned that a critical threshold has been crossed, meaning corals globally are likely to be eradicated due to global heating, which is increasing ocean temperatures to intolerable levels.

Researcher Insight

"Time is running out," stated the lead author of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to climate change, and absent immediate, ambitious actions to slow ocean warming and boost coral resilience, we face the danger of the extinction of additional coral species from reefs in Florida and worldwide."

The New Research

The recent study, published in the Science journal, examined 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 peak temperatures in more than a century and a half.

The two species are complex, reef-building corals and are identified because they look like, respectively, the antlers of male deer and elks.

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

Regional Impact

• Along the Florida Keys, death rates reached 98% and even 100%, showing a total eradication of the corals.
• In southeastern Florida, where temperatures have been lower, mortality rates were reduced, at about thirty-eight percent.

Past and Current Threats

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

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

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

If temperatures remain elevated, the corals perish completely.

Global Consequences

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

This poses a major threat to:

• A quarter of all ocean life that depends on what are effectively the marine rainforests.
• 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 worsened by increasing global heat.

Conservation Attempts

In a last-ditch effort to avert a death spiral of endangered corals, scientists have created repositories of Acropora in aquariums 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 escalate, there is little hope of long-term survival of these species absent major interventions, scientists caution.

Further Expert Commentary

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

"They were once abundant on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from inundation during storms, it is worthwhile taking exceptional steps to ensure we don't lose these corals completely."