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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 catastrophic losses.

What 'Functional Extinction' Means

The almost complete decline of these corals, which once formed the backbone of reefs in Florida and the Caribbean, indicates 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 preceding total extinction, a threat that now hangs for many coral species.

Researchers this month warned that a tipping point has been crossed, whereby corals around the world are set to be wiped out due to global heating, which is increasing ocean temperatures to unbearable levels.

Expert Insight

"We're running out of time," said Ross Cunning 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 boost coral resilience, we face the danger of the disappearance of even more corals from reefs in Florida and worldwide."

Details of the Recent Study

The new research, published in the journal Science, analyzed the outcome of staghorn and elkhorn corals off the Florida coast following a intense marine heatwave in 2023.

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

The two species are intricate, reef-building corals and are named because they resemble, in turn, the antlers of male deer and elks.

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 Impact

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

Past and Current Dangers

The two Acropora species had already suffered from many years of regional pressures in Florida, such as contaminated water from contaminants that run off the land, as well as disease.

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

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

If temperatures stay high, the corals perish entirely.

Worldwide Consequences

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.
• Millions of people who depend upon corals to support fish that they can consume and gain an income from.

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

Preservation Attempts

In a desperate attempt to prevent a death spiral of endangered corals, scientists have established repositories of Acropora in marine facilities and offshore coral nurseries.

Attempts have been made to replant corals on reefs in Florida, as well, in an effort to regain some of the ninety percent of coral cover disappeared off the state in the last forty years.

But as climate change continues to intensify, there is little hope of long-term survival of these species absent significant actions, scientists caution.

Further Expert Commentary

"Elkhorn species, in particular, are some of the most important wave-breaking coral species in the region," noted a study co-author, 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 extraordinary measures to ensure we preserve these corals completely."