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Researchers have found that two of the primary coral species forming Florida's reef have become ecologically extinct after a withering ocean heatwave led to devastating losses.

The Meaning Behind 'Functional Extinction' Means

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 once vital role in building and sustaining reef ecosystems that support a diversity of marine life.

Functional extinction is a phase preceding global extinction, a danger that now hangs for many coral species.

Researchers recently warned that a critical threshold had been reached, whereby corals around the world are set to be eradicated due to climate change, which is increasing ocean temperatures to intolerable levels.

Expert Insight

"Time is running out," stated the lead author of the recent research. "Extreme heatwaves are becoming more frequent and intense due to global warming, and without swift, decisive measures to reduce ocean heating and enhance coral survival, we face the danger of the disappearance of additional coral species from reefs in Florida and worldwide."

Details of the Recent Study

The recent study, published in the Science journal, analyzed the outcome of staghorn coral and elkhorn coral corals off the Florida coast following a intense 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 intricate, reef-building corals and are named because they resemble, respectively, the antlers of male deer and elk.

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

Geographic Effects

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

Past and Current Threats

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

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

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

If temperatures stay high, the corals die off completely.

Worldwide Implications

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

This presents a major threat to:

• One-fourth of all ocean life that relies upon what are effectively the marine rainforests.
• Millions of people who depend upon corals to support 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 rising global temperatures.

Preservation Efforts

In a desperate attempt to prevent a death spiral of threatened corals, scientists have established collections of Acropora in aquariums and offshore coral nurseries.

Attempts have been undertaken to replant corals on reefs in Florida, too, in an effort to regain some of the ninety percent of coral cover lost off the state in the past four decades.

But as climate change continues to intensify, there is slim chance of continued existence of these species absent major interventions, scientists caution.

Further Researcher Insight

"Elkhorn species, in particular, are some of the most important wave-breaking coral species in the region," said Andrew Baker, a ocean scientist at the Miami University.

"They were once common on shallow reef tops 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 completely."