🔗 Share this article

Researchers have found that two of the most important coral species forming Florida's reef have become ecologically extinct following a withering ocean heatwave caused catastrophic losses.

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once served as the backbone of reefs in Florida and the Caribbean, means they are no longer able to fulfill their once vital role in building and sustaining reef ecosystems that support a diversity of marine life.

Functional extinction is a stage before global extinction, a danger that now looms for many coral species.

Researchers recently warned that a critical threshold has been crossed, whereby corals around the world are likely to be wiped out due to climate change, which is raising ocean temperatures to unbearable levels.

Researcher Insight

"We're running out of time," stated Ross Cunning of the new Florida study. "Severe marine heatwaves are increasing in frequency and severity due to climate change, and without immediate, ambitious actions to slow ocean warming and enhance coral survival, we face the danger of the extinction of additional coral species from reefs in Florida and worldwide."

Details of the New Research

The new research, featured in the journal Science, analyzed the outcome 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 named because they look like, respectively, the antlers of male deer and elks.

However, researchers who performed underwater surveys of more than 52,000 colonies of the species, across 391 sites along Florida's coast, found extensive, often devastating, losses.

Geographic Impact

• Along the Florida Keys, mortality rates hit ninety-eight percent and even 100%, showing a total eradication of the corals.
• In southeastern Florida, where temperatures have been cooler, death rates were reduced, at about thirty-eight percent.

Historical and Present Threats

The two Acropora species had already endured from many years of regional pressures in Florida, such as contaminated water from contaminants that run off the land, as well as illness.

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

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

If temperatures remain elevated, the corals die off entirely.

Global Implications

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

This poses a significant danger to:

• A quarter of all ocean life that depends on what are essentially the rainforests of the sea.
• Hundreds of millions of people who depend upon corals to sustain fish that they can eat and gain an income from.

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

Preservation Attempts

In a desperate attempt to prevent a decline of endangered corals, scientists have established repositories of Acropora in aquariums and ocean-based nurseries.

Efforts have been undertaken to reseed corals on reefs in Florida, too, in an effort to regain some of the 90% of coral cover lost off the state in the past four decades.

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

Additional Expert Commentary

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

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