🔗 Share this article

Researchers have found that two of the most important coral species comprising Florida's reef are now functionally extinct following a intense ocean heatwave caused catastrophic losses.

The Meaning Behind 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once formed the backbone of reefs in Florida and the Caribbean, indicates they are no longer able to fulfill their once vital role in constructing and maintaining reef ecosystems that host a variety of marine life.

Functional extinction is a stage preceding total extinction, a threat that now hangs for many coral species.

Scientists recently alerted that a tipping point has been crossed, meaning corals around the world are likely to be wiped out due to global heating, which is increasing ocean temperatures to intolerable levels.

Researcher Perspective

"We're running out of time," stated Ross Cunning of the recent research. "Severe marine heatwaves are becoming more frequent and intense due to global warming, and without immediate, ambitious actions to reduce ocean heating and boost coral resilience, we face the danger of the extinction of even more corals from reefs in Florida and around the world."

Details of the Recent Study

The recent study, featured in the journal Science, analyzed the fate of staghorn coral and elkhorn corals off the Florida coast after a severe 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 named because they look like, respectively, the antlers of male deer and elk.

However, scientists 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 Effects

• In the Florida Keys, mortality rates reached ninety-eight percent and even 100%, showing a total eradication of the corals.
• In south-east Florida, where temperatures have been lower, death rates were lower, 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 poor water quality from pollutants that wash off the land, as well as illness.

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

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

If temperatures stay high, the corals die off completely.

Global Implications

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

This presents 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 consume and earn a livelihood from.

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

Conservation Attempts

In a desperate attempt to avert a death spiral of endangered corals, scientists have established repositories 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 restore some of the 90% of coral cover disappeared off the state in the past four decades.

But as climate change continues to intensify, there is little hope of long-term survival of these species without major interventions, scientists caution.

Further Researcher Insight

"Elkhorn corals, in particular, are some of the key wave-breaking coral species in the region," said Andrew Baker, a ocean scientist at the Miami University.

"They were once abundant on shallow reef crests 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 completely."