Florida Acropora Functionally Extinct After 2023 Heatwave

A multi-institutional study published in Science, led by NOAA’s Coral Reef Watch and the Shedd Aquarium, found that the 2023 record marine heat wave has rendered Florida’s elkhorn and staghorn corals functionally extinct along the roughly 350-mile reef. Researchers surveyed more than 52,000 Acropora colonies at nearly 400 sites and reported 97.8–100% mortality in the lower Florida Keys and Dry Tortugas and roughly 38% losses farther north. Sea-surface temperatures at or above about 31°C (87.8°F) for weeks to months produced accumulated heat stress 2.2–4 times higher than any year on record, triggering rapid bleaching and deaths that in some places occurred within days despite rescue and relocation attempts. The remaining colonies are now too sparse to reproduce or sustain historic reef-building roles, imperiling marine habitat and shoreline protection. Scientists say extreme warming compounded by decades of disease, storms, pollution and other stressors caused the sudden collapse and warn similar losses may follow elsewhere in the Caribbean. They say aggressive interventions (restoration, assisted gene flow) might preserve fragments locally but recovery will be limited and precarious without immediate, ambitious emissions reductions and sustained conservation funding.