Two Vital Florida Coral Species Deemed 'Functionally Extinct' After Devastating Ocean Heatwave

Scientists have discovered that two of the most important coral species comprising Florida's reef have become ecologically extinct following a withering ocean heatwave caused devastating 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 diversity of marine life.

Functional extinction is a phase preceding total extinction, a danger that now looms for many coral species.

Scientists recently alerted that a critical threshold had been reached, meaning corals around the world are likely to be eradicated due to climate change, which is raising ocean temperatures to intolerable levels.

Researcher Perspective

"Time is running out," stated Ross Cunning of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to global warming, and absent swift, decisive measures to reduce ocean heating and enhance coral survival, we face the danger of the extinction of additional coral species from reefs in Florida and around the world."

The New Research

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

This event elevated temperatures on Florida's fraying coral reefs to their highest levels in more than a century and a half.

The two species are complex, reef-forming corals and are identified because they look like, in turn, the antlers of male deer and elk.

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 devastating, losses.

Geographic Effects

• In the Florida Keys, mortality rates hit 98% and even one hundred percent, revealing a complete annihilation of the corals.
• In south-east Florida, where temperatures have been cooler, mortality rates were reduced, at about thirty-eight percent.

Past and Present Threats

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

But the 2023 heatwave has been fatal for these temperature-sensitive species.

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

If temperatures stay high, 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 relies upon what are effectively the rainforests of the sea.
• Hundreds of millions of people who depend upon corals to sustain fish that they can consume and gain an income from.

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

Conservation Efforts

In a last-ditch effort to avert a death spiral of endangered corals, scientists have established collections of Acropora in aquariums 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 lost off the state in the last forty years.

But as global heating continues to escalate, there is little hope of continued existence of these species absent significant actions, scientists caution.

Additional Expert Commentary

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

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