A Pair of Essential Florida Coral Species Declared 'Functionally Extinct' After Devastating Ocean Heatwave

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

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once formed the backbone of reefs in Florida and the Caribbean, indicates they can no longer fulfill their once vital role in building and sustaining reef ecosystems that host a diversity of marine life.

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

Researchers recently alerted that a tipping point had been reached, whereby corals around the world are set to be wiped out due to climate change, which is increasing ocean temperatures to intolerable levels.

Expert Insight

"Time is running out," stated Ross Cunning of the new Florida study. "Severe marine heatwaves are increasing in frequency and severity due to global warming, and without immediate, ambitious actions to reduce ocean heating and enhance coral survival, we risk the extinction of even more corals from reefs in Florida and around the world."

Details of the New Research

The recent study, published in the Science journal, 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 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 stags and elks.

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

Geographic Effects

• Along the Florida Keys, death rates hit 98% and even one hundred percent, showing a complete annihilation of the corals.
• In southeastern Florida, where temperatures have been cooler, mortality rates were reduced, at about 38%.

Historical and Current Dangers

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

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

The 2023 event caused the ninth occurrence of 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 perish completely.

Worldwide Implications

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

This presents a major threat to:

• A quarter of all ocean life that depends on what are effectively the marine rainforests.
• 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 safeguard our shorelines from intense hurricanes, which are themselves being worsened by rising global temperatures.

Conservation Attempts

In a desperate attempt to prevent a decline of threatened corals, scientists have established 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 lost off the state in the last forty years.

But as climate change continues to intensify, there is little hope of continued existence of these species without significant actions, researchers warn.

Further Researcher Insight

"Elkhorn species, in particular, are some of the most important wave-dampening coral species in the region," noted Andrew Baker, a marine biologist at the University of Miami.

"They were once common on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from inundation during storms, its worth taking exceptional steps to ensure we preserve these corals altogether."