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Abstract Coral reefs of the Florida Keys experienced the hottest summer on record in 2023, causing mass bleaching and mortality of scleractinian corals. Sea surface temperatures remained above 31°C for 41 days, exceeding all prior records for the region. Branching corals fared especially poorly, especiallyAcropora palmata, which has now been deemed functionally extinct across the entire Florida Reef Tract. High temperatures and prolonged thermal stress were the major causes of mortality. Our study investigates additional stressors contributing to coral mortality during the heatwave. Using benthic imagery, we show that during bleaching, coral tissue death is accelerated by proximity to disease. Using a Cox proportional hazard model, we found that, compared to initially healthy tissue on the same colony, disease lesions and neighboring tissue had a 3.8 times and 1.5 times higher risk of death, respectively. We show that these two stressors, working at different spatial scales, acted synergistically to increase mortality. Furthermore, from ourin situreef structural measurements, we found that during bleaching, coral survival was greatest along the reef edge. The reef displaces water, resulting in faster local velocity, which we hypothesize reduces the boundary layer at the tissue-water interface and thus simultaneously enhances the removal of cytotoxic metabolic wastes and the opportunity for coral heterotrophic feeding. Our findings reinforce the importance of the interactive effects of disease and reef topography on coral mortality, and suggest that restoration efforts should focus on reef edges where the chance of survival is improved relative to the reef interior.
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This content will become publicly available on October 23, 2026
Heat-driven functional extinction of Caribbean Acropora corals from Florida’s Coral Reef
In 2023, a record-setting marine heat wave triggered the ninth mass coral bleaching event on Florida’s Coral Reef (FCR). We examined spatial patterns of heat exposure along the ~560-kilometer length of FCR and the mortality of two ecologically important, critically endangered reef-building corals. Sea surface temperatures were ≥31°C for an average of 40.7 days, leading to heat exposures 2.2- to fourfold higher than all prior years on record. In the Florida Keys and Dry Tortugas, 97.8 to 100% of theAcropora palmataandAcropora cervicorniscolonies died. Mortality was lower offshore southeast Florida (37.9%), reflecting cooler temperatures in this region. Since the late 1970s, multiple stressors had already reduced the ecological relevance ofAcroporain Florida, but the 2023 heat wave marks their functional extinction from FCR.
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- PAR ID:
- 10654928
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Science Publishing Group
- Date Published:
- Journal Name:
- Science
- Volume:
- 390
- Issue:
- 6771
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 361 to 366
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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