Two Vital Florida Coral Species Declared 'Functionally Extinct' Following Severe Ocean Heatwave

Scientists have discovered that two of the primary coral species comprising Florida's reef have become functionally extinct after a intense ocean heatwave caused catastrophic losses.

What 'Functional Extinction' Signifies

The almost complete collapse of these corals, which once formed the foundation of reefs in Florida and the Caribbean, means they can no longer fulfill their once vital role in building and sustaining reef ecosystems that support a diversity of marine life.

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

Scientists recently alerted that a tipping point has been crossed, whereby corals globally are set to be wiped out due to climate change, which is increasing ocean temperatures to unbearable levels.

Researcher Insight

"We're running out of time," stated the lead author of the new Florida study. "Extreme heatwaves are becoming more frequent and intense due to climate change, and without 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 worldwide."

The Recent Study

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

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

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

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

Regional Effects

• Along the Florida Keys, death rates reached ninety-eight percent and even 100%, revealing 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 endured from many years of localized impacts in Florida, such as contaminated water from pollutants that run off the land, as well as illness.

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

The 2023 heat event caused the ninth occurrence of bleaching on the Florida reef – a phenomenon 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.

Global Consequences

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

This presents a significant danger to:

• A quarter of all ocean life that relies upon what are effectively the marine rainforests.
• Hundreds of millions of people who rely on corals to support fish that they can consume and earn a livelihood from.

Corals also act as a barrier to protect our shorelines from powerful storms, which are themselves being worsened by rising global temperatures.

Conservation Attempts

In a desperate attempt to prevent a death spiral of threatened corals, scientists have created collections of Acropora in marine facilities and ocean-based nurseries.

Efforts have been made to replant corals on reefs in Florida, as well, in an effort to regain some of the 90% of coral cover disappeared off the state in the past four decades.

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

Further Expert Commentary

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

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