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

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

The Meaning Behind 'Functional Extinction' Means

The almost complete decline of these corals, which once served as the foundation of reefs in Florida and the Caribbean, indicates they are no longer able to play their once vital role in building and sustaining reef ecosystems that support a diversity of marine life.

Ecological 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, whereby corals globally are likely to be eradicated due to climate change, which is increasing ocean temperatures to unbearable levels.

Researcher Perspective

"Time is running out," said Ross Cunning of the new Florida study. "Severe marine heatwaves are becoming more frequent and intense due to climate change, and absent immediate, ambitious actions to slow ocean warming and enhance coral survival, we face the danger of the disappearance 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 coral corals off the Florida coast after a intense 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-forming corals and are identified because they look like, in turn, the horns of male deer and elk.

However, scientists who conducted underwater surveys of over fifty-two thousand colonies of the species, across 391 sites along Florida's coast, found widespread, often catastrophic, losses.

Geographic Effects

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

Past and Current Threats

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

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

The 2023 heat event caused the ninth episode of 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 remain elevated, the corals perish completely.

Worldwide Consequences

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

This presents a major threat to:

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

Corals also serve as a barrier to safeguard our shorelines from powerful storms, which are themselves being intensified by increasing global heat.

Preservation Efforts

In a desperate attempt to avert a death spiral of endangered corals, scientists have created collections of Acropora in aquariums and offshore coral nurseries.

Efforts have been undertaken to replant corals on reefs in Florida, too, in an effort to restore some of the ninety percent of coral cover lost off the state in the past four decades.

But as global heating continues to intensify, there is slim chance of continued existence of these species without significant actions, researchers warn.

Further Researcher Insight

"Elkhorn species, in particular, are some of the key wave-dampening coral species in the area," said a study co-author, a marine biologist at the Miami University.

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