Florida's Ancient Acropora Coral Species Functionally Extinct After 2023 Heat Wave

A study released in the journal Science on October 23 has found that nearly all of Florida's critically endangered Acropora coral colonies are now dead, marking the species' functional extinction in Florida's Coral Reef. This decline is linked to a record-breaking ocean heat wave in 2023, which saw temperatures peak at 90.1 degrees in July. The study, conducted by researchers from Shedd Aquarium and Mote Marine Laboratory, tracked the health of 52,356 wild and restored Acropora coral colonies across the 350-mile length of Florida's coral reef.

Key Takeaways:

• Nearly all of Florida's Acropora coral colonies have died due to prolonged and extreme thermal stress, with between 97.8% and 100% of the two species of coral colonies in the Florida Keys and Dry Tortugas having perished by March 2024.
• The loss of Acropora corals is a devastating blow to the ecosystem, with these species having been the dominant reef-building corals in Florida for 10,000 years.
• The study found that the 2023 heatwave was up to 4 times more severe than any other heatwave on record, and the sheer magnitude of the heat stress and its effects on the corals was shocking.
• While most other coral species in Florida did not suffer losses as extreme as the more heat-sensitive Acropora, the loss of these species "stands as a stark warning for the future of coral reefs worldwide."
• Coral reefs, among the most heat-sensitive marine environments, have suffered decades of mass bleaching and mortality due to rising ocean temperatures.
• The loss of Acropora corals has significant implications for the ecosystem, with these species being major reef-builders in Florida and the Caribbean and having been a major focus of recent coral restoration efforts.
• Populations of other coral species in Florida that survived the 2023 heatwave continue to grow and build reefs, but most of these species grow more slowly than the staghorn and elkhorn and historically have not been as important for overall reef-building.

Statistics:

• 97.8% to 100% of Acropora coral colonies in the Florida Keys and Dry Tortugas died due to prolonged and extreme thermal stress by March 2024.
• 90.1 degrees: the peak temperature of the ocean heat wave in July 2023.
• 52,356: the number of wild and restored Acropora coral colonies tracked by the study.
• 350 miles: the length of Florida's coral reef covered by the study.
• 10,000 years: the length of time Acropora corals have been the dominant reef-building corals in Florida.
• 4 times: the severity of the 2023 heatwave compared to any other heatwave on record.

Sources:

• "Acropora coral colonies collapse due to extreme heat stress in 2023" (Science, October 23)
• Shedd Aquarium (statement)
• Mote Marine Laboratory (preserving coral reefs)