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

What 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once served as the foundation of reefs in Florida and the Caribbean, indicates they are no longer able to fulfill their previously crucial role in constructing and maintaining reef ecosystems that support a variety of marine life.

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

Researchers recently alerted that a tipping point has been crossed, whereby corals around the world are likely to be wiped out due to climate change, which is raising ocean temperatures to unbearable levels.

Expert Insight

"Time is running out," said Ross Cunning of the recent research. "Extreme heatwaves are becoming more frequent and intense due to global warming, and absent immediate, ambitious actions to reduce ocean heating and enhance coral survival, we face the danger of the extinction of additional coral species from reefs in Florida and worldwide."

Details of the New Research

The recent study, featured in the journal Science, analyzed the fate of staghorn and elkhorn coral corals off the Florida coast following a intense marine heatwave in 2023.

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

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

However, scientists who conducted diver surveys of over fifty-two thousand colonies of the species, across nearly four hundred sites along Florida's coast, found extensive, often devastating, losses.

Geographic Effects

• Along 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 cooler, death rates were reduced, at about thirty-eight percent.

Past and Present Dangers

The two Acropora species had already endured from many years of localized impacts 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 heat event caused the ninth episode of bleaching on the Florida reef – a process whereby corals become heat-stressed and expel the algae partners living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals die off entirely.

Global Implications

Worldwide, coral reefs are among the ecosystems most vulnerable to the anthropogenic climate emergency.

This presents a major threat to:

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

Corals also act as a barrier to protect our shorelines from intense hurricanes, which are themselves being worsened by increasing global heat.

Conservation Attempts

In a desperate attempt to avert a death spiral of threatened corals, scientists have created repositories of Acropora in marine facilities and offshore coral nurseries.

Attempts have been made to replant corals on reefs in Florida, too, in an effort to restore some of the ninety percent of coral cover lost off the state in the last forty years.

But as climate change continues to intensify, there is little hope of continued existence of these species without major interventions, scientists caution.

Further Researcher Insight

"Elkhorn species, in particular, are some of the key wave-breaking coral species in the region," noted Andrew Baker, a marine biologist 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 inundation during storms, it is worthwhile taking extraordinary measures to ensure we preserve these corals altogether."