🔗 Share this article A Pair of Essential Florida Coral Species Deemed 'Functionally Extinct' After Devastating Ocean Heatwave Researchers have found that two of the key coral species forming Florida's reef have become functionally extinct after a withering ocean heatwave led to devastating losses. What 'Functional Extinction' Signifies The almost complete collapse of these corals, which once formed the backbone of reefs in Florida and the Caribbean, means they are no longer able to play their previously crucial role in building and sustaining reef ecosystems that host a diversity of marine life. Functional extinction is a phase before global extinction, a threat that now looms for many coral species. Researchers this month alerted that a critical threshold had been reached, whereby corals around the world are likely to be wiped out due to global heating, which is raising ocean temperatures to intolerable levels. Researcher Insight "We're running out of time," said the lead author of the new Florida study. "Severe marine heatwaves are becoming more frequent and intense due to global warming, and without immediate, ambitious actions to slow ocean warming and enhance coral survival, we risk the disappearance of even more corals from reefs in Florida and around the world." The New Research The new research, published in the Science journal, analyzed the outcome of staghorn coral and elkhorn corals off the Florida coast after a severe marine heatwave in 2023. This event elevated temperatures on Florida's deteriorating coral reefs to their peak temperatures in over 150 years. The two species are complex, reef-forming corals and are identified because they look like, in turn, the horns of stags and elks. However, scientists who performed diver surveys of over fifty-two thousand colonies of the species, across nearly four hundred sites along Florida's coast, found extensive, often devastating, losses. Regional Impact In the Florida Keys, mortality rates hit 98% and even one hundred percent, revealing a total eradication of the corals. In southeastern Florida, where temperatures have been lower, death rates were lower, at about thirty-eight percent. Past and Current 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 been lethal for these temperature-sensitive species. The 2023 heat event caused the ninth occurrence of bleaching on the Florida reef – a process whereby corals become heat-stressed and expel the symbiotic algae living in their tissues, causing them to become bleached white. If temperatures remain elevated, the corals perish entirely. Worldwide Consequences Globally, coral reefs are among the ecosystems most at risk to the human-caused climate emergency. This presents a significant danger to: A quarter of all ocean life that relies upon 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 intensified by increasing global heat. Preservation Attempts In a last-ditch effort to avert a death spiral of endangered corals, scientists have established collections of Acropora in marine facilities and ocean-based nurseries. Attempts have been undertaken to reseed 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 little hope of continued existence of these species without significant actions, scientists caution. Additional Researcher Insight "Elkhorn corals, especially, are some of the key wave-breaking coral species in the region," 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 exceptional steps to ensure we preserve these corals completely."