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Scientists have discovered that two of the key coral species forming Florida's reef are now functionally extinct after a intense ocean heatwave caused catastrophic losses.

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once formed the foundation of reefs in Florida and the Caribbean, means they can no longer play their once vital role in building and sustaining reef ecosystems that host a variety of marine life.

Ecological extinction is a phase preceding global extinction, a danger that now looms for many coral species.

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

Researcher 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 slow ocean warming and boost coral resilience, we risk the extinction of even more corals from reefs in Florida and worldwide."

Details of the Recent Study

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

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

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

However, researchers who performed underwater surveys of over fifty-two thousand colonies of the species, across nearly four hundred sites along Florida's coast, found widespread, often catastrophic, losses.

Geographic Impact

• In the Florida Keys, death rates reached 98% and even one hundred percent, revealing a total eradication 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 run off the land, as well as disease.

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

The 2023 event caused the ninth episode 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 bleached white.

If temperatures remain elevated, the corals die off entirely.

Global Implications

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

This presents a major threat to:

• A quarter of all ocean life that depends on what are essentially the rainforests of the sea.
• Millions of people who depend upon corals to sustain fish that they can consume and gain an income from.

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

Preservation Efforts

In a desperate attempt to avert a death spiral of endangered corals, scientists have created repositories of Acropora in marine facilities and ocean-based nurseries.

Attempts have been made to reseed corals on reefs in Florida, as well, in an effort to restore some of the 90% of coral cover disappeared 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, scientists caution.

Further Researcher Insight

"Elkhorn corals, in particular, are some of the key wave-breaking coral species in the area," noted a study co-author, a ocean scientist at the Miami University.

"They were once common on shallow reef crests in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, it is worthwhile taking extraordinary measures to ensure we don't lose these corals altogether."