Heterotrophy, microbiome, and location effects on restoration efficacy of the threatened coral Acropora palmata

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 replicate A. palmata colonies 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 for A. palmata.