A recent and intense marine heat wave in 2023 has wiped out two crucial coral species on Florida’s Coral Reef, researchers report. These species, known as elkhorn and staghorn corals, once played a vital role in building and expanding the reef that stretches 350 miles along Florida’s southeastern and southern coasts.
The loss is significant because these corals help protect Florida’s coastal cities from storms by reducing wave energy and preventing erosion. They also provide important habitats for fish and other marine life that support commercial fisheries. Scientists warn that with these corals now “functionally extinct,” the reef’s ability to recover and continue protecting the coastline is greatly weakened.
This devastating event follows years of trouble for Florida’s corals. Pollution, disease, overfishing, and eight previous marine heat waves since 1987 have already damaged the reef’s health. But the 2023 heat wave was different — it exposed the reef to water temperatures above 88°F (31°C) for around 40 days, with some places reaching a record 101°F (38.3°C). This sudden and severe heat stress killed the corals within days.
Scientists surveyed thousands of coral colonies across the reef. Nearly all the elkhorn and staghorn corals on the west side of the reef died, with significant losses even in cooler southeastern waters. This brings to three the number of coral species now functionally extinct on the reef, with the pillar coral lost as early as 2020.
Efforts are underway to save what remains. Researchers have been planting new corals, including some bred to withstand warmer waters and experimenting with heat-resistant algae that live inside corals to help them survive hot spells. However, experts stress these efforts won’t be enough unless greenhouse gas emissions are sharply reduced.
Ross Cunning, a lead researcher from the Shedd Aquarium, explained that without tackling climate change, the outlook for Florida’s reef and coral reefs worldwide is bleak. The reef supports not only wildlife but also an estimated $2.7 trillion a year in global goods and services. As ocean temperatures rise, heat waves like the one in 2023 are expected to become more common, putting coral reefs and coastal communities everywhere at greater risk.