Post-Heatwave Coral Health Coincides With Host-Specific Symbiodiniaceae-Bacteria Consortia

Area of Science:

• Marine biology
• Ecology
• Microbial ecology

Background:

• Coral reefs are threatened by climate-driven marine heatwaves (MHWs).
• Coral health is linked to symbiotic microalgae (Symbiodiniaceae) and bacteria.
• The role of these microbial interactions in coral thermal resilience is not fully understood.

Purpose of the Study:

• To investigate how Symbiodiniaceae-bacteria consortia influence coral health and resilience during marine heatwaves.
• To compare the symbiotic strategies of two coral species, Porites lutea and Duncanopsammia peltata, under thermal stress.

Main Methods:

• Monitoring coral health and analyzing Symbiodiniaceae and bacterial communities in two coral species during a marine heatwave.
• Utilizing molecular techniques to characterize microbial consortia and assess their relationship with coral physiological states (healthy vs. bleached).

Main Results:

• Porites lutea showed thermal resilience, maintaining a stable symbiosis with heat-tolerant Cladocopium C15 and conservative bacterial changes.
• Duncanopsammia peltata shifted between heat-sensitive (Cladocopium C1) and heat-tolerant (Durusdinium D1/D4) Symbiodiniaceae, exhibiting more dynamic bacterial community shifts.
• These distinct responses suggest a specialist strategy in P. lutea and a generalist strategy in D. peltata regarding microbial partner selection.

Conclusions:

• Coral health during MHWs is characterized by specific Symbiodiniaceae-bacteria consortia, reflecting host-specific strategies.
• An evolutionary trade-off exists between stable symbioses for chronic stress persistence and rapid microbiome turnover for bleaching resilience.
• Understanding these host-microbe interactions is crucial for developing effective coral conservation and restoration strategies in a changing climate.