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Scientists have discovered that two of the primary coral species comprising Florida's reef are now functionally extinct following a intense ocean heatwave led to catastrophic losses.

The Meaning Behind 'Functional Extinction' Means

The almost complete collapse of these corals, which once served as the foundation of reefs in Florida and the Caribbean, indicates they can no longer fulfill their previously crucial role in building and sustaining reef ecosystems that host a variety of marine life.

Functional extinction is a stage preceding total extinction, a threat that now looms for many coral species.

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

Researcher Perspective

"We're running out of time," stated the lead author of the recent research. "Extreme heatwaves are increasing in frequency and severity due to climate change, and absent swift, decisive measures to slow ocean warming and enhance coral survival, we risk the extinction of even more corals from reefs in Florida and worldwide."

The New Research

The new research, published in the Science journal, analyzed the fate 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 highest levels in over 150 years.

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

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

Regional Impact

• Along the Florida Keys, mortality rates reached ninety-eight percent and even 100%, showing a complete annihilation of the corals.
• In south-east Florida, where temperatures have been lower, mortality rates were lower, at about 38%.

Historical and Current Dangers

The two Acropora species had already suffered from decades of localized impacts in Florida, such as contaminated water from pollutants that wash off the land, as well as disease.

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

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

If temperatures remain elevated, the corals die off completely.

Global Consequences

Globally, coral reefs are among the ecosystems most vulnerable to the anthropogenic climate crisis.

This poses a major threat to:

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

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

Preservation Attempts

In a desperate attempt to prevent a decline of endangered corals, scientists have created repositories of Acropora in aquariums 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 disappeared 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 significant actions, researchers warn.

Further Expert Commentary

"Elkhorn corals, in particular, are some of the key wave-breaking coral species in the area," said Andrew Baker, a marine biologist at the University of Miami.

"They used to be common on shallow reef crests 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."