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

The Meaning Behind 'Functional Extinction' Means

The near-total collapse of these corals, which once formed the backbone of reefs in Florida and the Caribbean, indicates they are no longer able to play their previously crucial role in building and sustaining reef ecosystems that host a variety of marine life.

Ecological extinction is a stage preceding global extinction, a danger that now hangs for many coral species.

Scientists recently alerted that a tipping point had been reached, whereby corals around the world are likely to be eradicated due to global heating, which is raising ocean temperatures to unbearable levels.

Expert Insight

"We're running out of time," stated the lead author of the new Florida study. "Extreme heatwaves are increasing in frequency and severity due to climate change, and without immediate, ambitious actions to reduce ocean heating and boost coral resilience, we risk the disappearance of even more corals from reefs in Florida and worldwide."

Details of the New Research

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 peak temperatures in more than a century and a half.

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

However, researchers who conducted diver surveys of more than 52,000 colonies of the species, across nearly four hundred sites along Florida's coast, found widespread, often catastrophic, losses.

Geographic Effects

• Along the Florida Keys, mortality rates hit ninety-eight percent and even 100%, revealing a total eradication of the corals.
• In southeastern Florida, where temperatures have been cooler, death rates were reduced, at about 38%.

Past and Present Dangers

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

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

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

If temperatures remain elevated, the corals die off entirely.

Global Implications

Globally, coral reefs are among the ecosystems most vulnerable to the anthropogenic climate crisis.

This presents a significant danger to:

• One-fourth of all ocean life that depends on what are essentially the rainforests of the sea.
• 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 worsened by rising global temperatures.

Preservation Attempts

In a desperate attempt to prevent a decline of threatened corals, scientists have created collections of Acropora in marine facilities and offshore coral nurseries.

Attempts have been made to replant corals on reefs in Florida, too, in an effort to restore some of the 90% of coral cover disappeared off the state in the last forty years.

But as global heating continues to escalate, there is slim chance of continued existence of these species absent significant actions, researchers warn.

Further Expert Commentary

"Elkhorn corals, in particular, are some of the key wave-dampening coral species in the area," said a study co-author, a ocean scientist at the University of Miami.

"They used to be abundant on shallow reef tops in the Caribbean, and if we want our reefs to continue protecting our coastlines from inundation during storms, it is worthwhile taking exceptional steps to ensure we don't lose these corals altogether."