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Researchers have found that two of the primary coral species comprising Florida's reef are now ecologically extinct after a intense ocean heatwave led to devastating losses.

The Meaning Behind 'Functional Extinction' Means

The near-total 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 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.

Scientists this month alerted that a tipping point has been crossed, whereby corals around the world are set to be wiped out due to climate change, which is increasing ocean temperatures to unbearable levels.

Researcher Perspective

"We're running out of time," said Ross Cunning of the new Florida study. "Extreme heatwaves are increasing in frequency and severity due to global warming, and absent immediate, ambitious actions to reduce ocean heating and boost coral resilience, we face the danger of the disappearance 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 outcome of staghorn and elkhorn coral corals off the Florida coast after 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 intricate, reef-building corals and are named because they resemble, in turn, the antlers of stags and elk.

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 extensive, often catastrophic, losses.

Geographic Effects

• Along the Florida Keys, death rates reached ninety-eight percent and even 100%, revealing a total eradication of the corals.
• In southeastern Florida, where temperatures have been cooler, death rates were reduced, at about thirty-eight percent.

Historical and Current Dangers

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

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

The 2023 event caused the ninth episode of 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 perish entirely.

Global Consequences

Worldwide, coral reefs are among the ecosystems most at risk to the anthropogenic climate crisis.

This poses a significant danger to:

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

Corals also act as a protective barrier to protect our shorelines from powerful storms, which are themselves being intensified by rising global temperatures.

Conservation Efforts

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

Attempts have been made to reseed 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 escalate, there is slim chance of continued existence of these species absent major interventions, researchers warn.

Additional Researcher Insight

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

"They used to be abundant on shallow reef tops in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from inundation during storms, its worth taking extraordinary measures to ensure we don't lose these corals altogether."