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

Researchers have found that two of the key coral species comprising Florida's reef have become ecologically extinct after a withering ocean heatwave led to catastrophic losses.

What 'Functional Extinction' Signifies

The near-total collapse of these corals, which once formed the foundation of reefs in Florida and the Caribbean, indicates they can no longer play their previously crucial role in constructing and maintaining reef ecosystems that host a variety of marine life.

Ecological extinction is a phase preceding global extinction, a danger that now hangs for many coral species.

Scientists this month warned that a tipping point had been reached, meaning corals globally are set to be wiped out due to global heating, which is increasing ocean temperatures to intolerable levels.

Expert Perspective

"Time is running out," said the lead author of the recent research. "Extreme heatwaves are increasing in frequency and severity due to global warming, and absent immediate, ambitious actions to reduce ocean heating and boost coral resilience, we face the danger of the disappearance of additional coral species from reefs in Florida and worldwide."

The Recent Study

The recent study, published in the Science journal, examined 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 peak temperatures in over 150 years.

The two species are intricate, reef-forming corals and are named because they look like, respectively, the antlers of stags and elk.

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

Regional Impact

• In the Florida Keys, mortality rates reached ninety-eight percent and even one hundred percent, showing a total eradication of the corals.
• In southeastern Florida, where temperatures have been cooler, death rates were lower, 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 wash off the land, as well as disease.

But the 2023 marine heatwave has proved 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 heat-stressed and eject the symbiotic algae living in their tissues, causing them to become ghostly white.

If temperatures remain elevated, the corals die off entirely.

Worldwide Implications

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

This presents a significant danger to:

• One-fourth of all ocean life that relies upon what are effectively the rainforests of the sea.
• Hundreds of millions of people who rely on corals to sustain fish that they can eat and gain an income from.

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

Preservation Attempts

In a desperate attempt to avert a decline of threatened corals, scientists have established collections of Acropora in marine facilities and ocean-based nurseries.

Efforts 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 global heating continues to escalate, there is slim chance of long-term survival of these species without significant actions, researchers warn.

Further Expert Commentary

"Elkhorn corals, 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 common 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."