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

The Meaning Behind 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once formed the backbone of reefs in Florida and the Caribbean, indicates they are no longer able to fulfill their previously crucial role in building and sustaining reef ecosystems that support a diversity of marine life.

Functional extinction is a phase preceding total extinction, a threat that now hangs for many coral species.

Researchers this month alerted that a tipping point has been crossed, meaning corals globally are likely to be eradicated due to global heating, which is increasing ocean temperatures to unbearable levels.

Expert Perspective

"Time is running out," stated the lead author of the recent research. "Severe marine heatwaves are increasing in frequency and severity due to climate change, 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 worldwide."

The Recent Study

The recent study, featured in the journal Science, examined the outcome of staghorn and elkhorn corals off the Florida coast after a intense marine heatwave in 2023.

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

The two species are complex, reef-forming corals and are named because they resemble, in turn, the antlers of stags and elks.

However, researchers 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 catastrophic, losses.

Regional Impact

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

Historical and Current Threats

The two Acropora species had already endured from decades of regional pressures in Florida, such as poor water quality from pollutants that run off the land, as well as illness.

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

The 2023 event caused the ninth occurrence 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 ghostly white.

If temperatures stay high, the corals perish entirely.

Global Implications

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

This presents a significant danger to:

• A quarter of all ocean life that relies upon what are effectively the marine rainforests.
• Millions of people who rely on corals to sustain fish that they can eat and earn a livelihood from.

Corals also act as a protective barrier to safeguard our shorelines from intense hurricanes, which are themselves being intensified by rising global temperatures.

Conservation Efforts

In a desperate attempt to prevent a decline of threatened corals, scientists have created collections of Acropora in marine facilities and offshore coral nurseries.

Attempts have been undertaken to reseed 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 escalate, there is little hope of continued existence of these species without major interventions, researchers warn.

Further Researcher Insight

"Elkhorn species, in particular, are some of the most important wave-breaking coral species in the area," said Andrew Baker, 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 continue protecting our coastlines from inundation during storms, its worth taking extraordinary measures to ensure we don't lose these corals altogether."