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Scientists have discovered that two of the most important coral species forming Florida's reef have become functionally extinct following a intense ocean heatwave led to catastrophic losses.

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once served as the backbone of reefs in Florida and the Caribbean, means they are no longer able to play their previously crucial role in constructing and maintaining reef ecosystems that support a diversity of marine life.

Functional extinction is a phase before total extinction, a danger that now hangs for many coral species.

Researchers this month alerted that a critical threshold has been crossed, meaning corals around the world are likely to be eradicated due to global heating, which is raising ocean temperatures to intolerable levels.

Expert Insight

"We're running out of time," stated the lead author of the new Florida study. "Severe marine heatwaves are increasing in frequency and severity due to global warming, and absent swift, decisive measures to reduce ocean heating and boost coral resilience, we risk the extinction of even more corals from reefs in Florida and around the world."

The New Research

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

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

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

However, scientists who performed diver 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

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

Past and Current Dangers

The two Acropora species had already endured from many years of localized impacts in Florida, such as poor water quality from contaminants that wash off the land, as well as disease.

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

The 2023 event caused the ninth episode of coral bleaching on the Florida reef – a phenomenon whereby corals become thermally stressed and expel the symbiotic algae living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals die off completely.

Worldwide Consequences

Globally, coral reefs are among the ecosystems most at risk to the anthropogenic climate emergency.

This poses a major threat to:

• One-fourth of all ocean life that depends on what are essentially the marine rainforests.
• Millions of people who depend upon corals to sustain fish that they can eat and earn a livelihood from.

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

Conservation Attempts

In a desperate attempt to prevent a decline of endangered corals, scientists have established repositories of Acropora in marine facilities and offshore coral nurseries.

Efforts have been undertaken to reseed corals on reefs in Florida, too, in an effort to regain some of the 90% of coral cover lost off the state in the past four decades.

But as global heating continues to escalate, there is slim chance of long-term survival of these species without major interventions, scientists caution.

Further Researcher Insight

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

"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 preserve these corals altogether."