🔗 Share this article

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

What 'Functional Extinction' Means

The almost complete decline of these corals, which once formed the backbone of reefs in Florida and the Caribbean, indicates they can no longer fulfill their previously crucial role in constructing and maintaining reef ecosystems that support a diversity of marine life.

Functional extinction is a phase before global extinction, a threat that now hangs for many coral species.

Scientists recently alerted that a critical threshold had been reached, whereby corals globally are set to be eradicated due to global heating, which is increasing ocean temperatures to unbearable levels.

Expert Perspective

"We're running out of time," said the lead author of the new Florida study. "Extreme heatwaves are increasing in frequency and severity due to climate change, and without swift, decisive measures to reduce ocean heating and boost coral resilience, we face the danger of the disappearance of additional coral species from reefs in Florida and around the world."

The Recent Study

The new research, published in the Science journal, examined the fate of staghorn and elkhorn corals off the Florida coast following a intense marine heatwave in 2023.

This event elevated temperatures on Florida's fraying coral reefs to their highest levels in over 150 years.

The two species are complex, reef-forming corals and are identified because they look like, in turn, the horns of stags 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 widespread, often devastating, losses.

Regional Impact

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

Historical and Current Threats

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

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

The 2023 heat event caused the ninth occurrence 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 ghostly 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 poses a significant danger to:

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

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

Conservation Attempts

In a desperate attempt to prevent a death spiral of endangered corals, scientists have established repositories of Acropora in marine facilities and offshore coral nurseries.

Efforts have been undertaken to replant corals on reefs in Florida, as well, 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 long-term survival of these species without significant actions, researchers warn.

Additional Researcher Insight

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

"They used to be abundant on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, it is worthwhile taking exceptional steps to ensure we preserve these corals completely."