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

What 'Functional Extinction' Signifies

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

Functional extinction is a stage preceding total extinction, a danger that now looms for many coral species.

Researchers recently warned that a tipping point had been reached, meaning corals around the world are likely to be wiped out due to climate change, which is increasing ocean temperatures to intolerable levels.

Expert Perspective

"We're running out of time," stated the lead author 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 disappearance of additional coral species from reefs in Florida and around the world."

The New Research

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

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

The two species are complex, reef-forming corals and are identified because they look like, in turn, the antlers of male deer and elk.

However, researchers who performed 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.

Regional Effects

• In the Florida Keys, death rates reached 98% and even 100%, showing a complete annihilation of the corals.
• In south-east Florida, where temperatures have been cooler, death rates were reduced, at about thirty-eight percent.

Historical and Current Dangers

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

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

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

If temperatures remain elevated, the corals perish entirely.

Global Implications

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

This poses a major threat to:

• A quarter of all ocean life that relies upon what are essentially the marine rainforests.
• Hundreds of millions of people who rely on corals to support fish that they can consume and earn a livelihood from.

Corals also serve as a protective barrier to protect our shorelines from powerful storms, which are themselves being worsened by rising global temperatures.

Conservation Efforts

In a desperate attempt to prevent a decline of endangered corals, scientists have created collections of Acropora in aquariums and ocean-based nurseries.

Attempts have been undertaken to reseed corals on reefs in Florida, as well, in an effort to restore some of the 90% of coral cover lost off the state in the last forty years.

But as global heating continues to escalate, there is little hope of long-term survival of these species without major interventions, researchers warn.

Additional Researcher Insight

"Elkhorn species, especially, are some of the key wave-dampening coral species in the region," said a study co-author, a marine biologist at the Miami University.

"They were once common on shallow reef tops in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from inundation during storms, it is worthwhile taking exceptional steps to ensure we preserve these corals altogether."