Destabilization of mutualistic interactions shapes the early heat stress response of the coral holobiont.

Background: The stability of the symbiotic relationship between coral and their dinoflagellate algae (Symbiodiniaceae) is disrupted by ocean warming. Although the coral thermal response depends on the complex interactions between host, Symbiodiniaceae and prokaryotes, the mechanisms underlying the initial destabilization of these symbioses are poorly understood.

Results: In a 2-month manipulative experiment, we exposed the coral Porites lutea to gradually increasing temperatures corresponding to 0-8 degree heating weeks (DHW) and assessed the response of the coral holobiont using coral and Symbiodiniaceae transcriptomics, microbial 16S rRNA gene sequencing and physiological measurements.