A Pair of Essential Florida Coral Species Declared 'Functionally Extinct' After Devastating Ocean Heatwave

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

The Meaning Behind 'Functional Extinction' Signifies

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

Ecological extinction is a stage before global extinction, a threat that now looms for many coral species.

Researchers recently warned that a tipping point has been crossed, whereby corals globally are set to be wiped out due to climate change, which is raising ocean temperatures to intolerable levels.

Expert Perspective

"Time is running out," stated Ross Cunning of the recent research. "Extreme heatwaves are becoming more frequent and intense due to global warming, and without immediate, ambitious actions to reduce ocean heating and enhance coral survival, we risk the extinction of additional coral species from reefs in Florida and worldwide."

Details of the New Research

The recent study, published in the Science journal, analyzed the fate 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 complex, reef-building corals and are identified because they look like, in turn, the antlers of stags and elk.

However, scientists who performed underwater surveys of over fifty-two thousand colonies of the species, across nearly four hundred sites along Florida's coast, found widespread, often devastating, losses.

Geographic Effects

• Along the Florida Keys, death rates reached 98% and even one hundred percent, revealing a total eradication of the corals.
• In south-east Florida, where temperatures have been cooler, mortality rates were lower, at about thirty-eight percent.

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 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 bleaching on the Florida reef – a phenomenon whereby corals become thermally stressed and eject the symbiotic algae living in their tissues, causing them to become bleached white.

If temperatures stay high, the corals perish entirely.

Worldwide Consequences

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

This poses a significant danger to:

• One-fourth of all ocean life that depends on what are essentially the marine rainforests.
• Hundreds of millions of people who depend upon corals to support fish that they can consume and earn a livelihood from.

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

Preservation Efforts

In a last-ditch effort to prevent a death spiral of threatened corals, scientists have created collections 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 ninety percent of coral cover disappeared 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 absent significant actions, scientists caution.

Further Researcher Insight

"Elkhorn corals, in particular, are some of the most important wave-dampening coral species in the region," said 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 keep safeguarding our coastlines from inundation during storms, its worth taking extraordinary measures to ensure we preserve these corals completely."