🔗 Share this article

Scientists have discovered that two of the primary coral species comprising Florida's reef have become functionally extinct after a withering ocean heatwave led to devastating losses.

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once served as the backbone of reefs in Florida and the Caribbean, means they can no longer fulfill their previously crucial role in building and sustaining reef ecosystems that support a variety of marine life.

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

Scientists this month warned that a critical threshold had been reached, whereby corals globally are set to be wiped out due to global heating, which is increasing ocean temperatures to unbearable levels.

Researcher Insight

"Time is running out," stated the lead author of the recent research. "Extreme heatwaves are increasing in frequency and severity due to global warming, and absent swift, decisive measures to slow ocean warming and enhance coral survival, we risk the extinction of additional coral species from reefs in Florida and around the world."

Details of 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 intense marine heatwave in 2023.

This event raised temperatures on Florida's deteriorating coral reefs to their peak temperatures in over 150 years.

The two species are intricate, reef-building corals and are identified because they look like, respectively, the antlers of male deer 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.

Geographic Impact

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

Past and Present Dangers

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 disease.

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

The 2023 event caused the ninth episode of coral bleaching on the Florida reef – a phenomenon whereby corals become thermally stressed and expel 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 major threat to:

• A quarter of all ocean life that relies upon what are essentially the rainforests of the sea.
• 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 intense hurricanes, which are themselves being intensified by increasing global heat.

Conservation Attempts

In a last-ditch effort to avert a decline of threatened corals, scientists have established collections of Acropora in marine facilities and ocean-based nurseries.

Attempts have been undertaken to replant 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 past four decades.

But as climate change continues to intensify, there is slim chance of continued existence of these species absent significant actions, scientists caution.

Additional Researcher Insight

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

"They used to be common on shallow reef crests in the Caribbean, and if we want our reefs to continue protecting our coastlines from flooding during storms, its worth taking exceptional steps to ensure we preserve these corals completely."