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Abstract The iconic and threatened Caribbean coral,Acropora palmata, is an essential reef-ecosystem engineer. Understanding the processes underpinning this coral’s survival and growth is essential to restoring this foundational species. Here, we compared replicateA. palmatacolonies transplanted along 350 km of Florida’s offshore coral reef to determine holobiont and/or environmental variables that predict transplant success. We found a west-to-east gradient in coral physiology coupled with site-specific coral-associated microbiomes. Interestingly, no variables were linked to coral genet. Our results suggest that the unique oceanographic conditions with periodic upwelling events in the Dry Tortugas provide corals with greater opportunity for heterotrophy that in turn enhances coral growth and survivorship, and positively influences the microbiome. Our findings indicate that restoration efforts in the Dry Tortugas, and other places exhibiting higher food availability, could be most effective forA. palmata.
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This content will become publicly available on June 1, 2026
Heat-tolerant algal symbionts may prevent extirpation of the threatened elkhorn coral, Acropora palmata, in Florida during intensifying marine heatwaves
Abstract The elkhorn coral,Acropora palmata, was historically a major reef-building species in the Caribbean, but has suffered devastating declines in recent decades. Despite significant restoration efforts in Florida, the marine heatwave of 2023 caused severe bleaching and mortality to both wild and restored colonies. To understand the disastrous impacts, we evaluated the variation in heat tolerance among Florida’sA. palmatapopulation prior to the event. In 2022, we used rapid acute heat stress assays to assess the thermal tolerance of 172 adult colonies (125 unique genets) from four nurseries. We found variation in thermal tolerance (4.17°C range in ED50) that was attributed to nursery location (17.2% of variation), genet (25.9%), and symbiont abundance (15.6%). Algal symbiont type, however, was the strongest predictor of thermal performance, with the few (n = 10) colonies hostingDurusdiniumbeing, on average, 1.9°C more thermally tolerant than corals hostingSymbiodinium. This difference would have decreased the effective heat stress accumulation during the 2023 event by ~92%. Therefore, despite considerable variation in thermal tolerance among Florida’s elkhorn corals, hostingDurusdiniumappears to be the most effective mechanism for surviving such extreme heat stress. These findings suggest that restoration strategies that focus on rearing sexually derivedA. palmatarecruits withDurusdinium, followed by outplanting to suitable environments, may improve survival during future heatwaves. Combined with efforts to introduce additional elkhorn diversity from populations outside Florida, these approaches may be the most effective interventions to promote the continued survival of Florida’s elkhorn corals in the face of rapid climate change.
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- Award ID(s):
- 1851305
- PAR ID:
- 10610530
- Publisher / Repository:
- Coral Reefs
- Date Published:
- Journal Name:
- Coral Reefs
- Volume:
- 44
- Issue:
- 3
- ISSN:
- 0722-4028
- Page Range / eLocation ID:
- 953 to 965
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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