A Pair of Essential Florida Coral Species Declared '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 intense ocean heatwave caused catastrophic losses.

The Meaning Behind 'Functional Extinction' Signifies

The near-total decline of these corals, which once formed the foundation of reefs in Florida and the Caribbean, indicates they are no longer able to fulfill their once vital role in building and sustaining reef ecosystems that support a variety of marine life.

Ecological extinction is a stage before total extinction, a threat that now hangs for many coral species.

Scientists recently alerted that a tipping point had been reached, whereby corals globally are set to be wiped out due to global heating, which is raising ocean temperatures to intolerable levels.

Expert Insight

"We're running out of time," said the lead author of the recent research. "Extreme heatwaves are becoming more frequent and intense due to climate change, and absent swift, decisive measures to reduce ocean heating and enhance coral survival, we face the danger of the disappearance of additional coral species from reefs in Florida and around the world."

The Recent Study

The recent study, featured in the journal Science, examined the outcome of staghorn coral and elkhorn corals off the Florida coast following a severe marine heatwave in 2023.

This event raised 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 named because they resemble, in turn, the horns of male deer and elks.

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

Geographic Effects

• Along the Florida Keys, mortality rates reached ninety-eight percent and even 100%, revealing a complete annihilation of the corals.
• In south-east Florida, where temperatures have been cooler, mortality rates were lower, at about 38%.

Historical and Current Threats

The two Acropora species had already endured from decades of regional pressures in Florida, such as contaminated water from pollutants that wash off the land, as well as illness.

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

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

If temperatures stay high, the corals perish completely.

Global Consequences

Globally, coral reefs are among the ecosystems most vulnerable to the human-caused climate emergency.

This poses a significant danger to:

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

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

Conservation Efforts

In a last-ditch effort to prevent a decline of endangered 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, as well, 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 escalate, there is slim chance of continued existence of these species without major interventions, scientists caution.

Further Researcher Insight

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

"They were once abundant on shallow reef crests in the Caribbean, and if we want our reefs to keep safeguarding our coastlines from inundation during storms, it is worthwhile taking extraordinary measures to ensure we preserve these corals altogether."