Microbiome dynamics of two differentially resilient corals

Area of Science:

• Marine Biology
• Microbial Ecology
• Coral Reef Ecology

Background:

• Coral bleaching and disease significantly contribute to the decline of coral cover globally.
• Understanding coral-microbe interactions under environmental stressors like warming and acidification is vital for predicting coral health.
• Diploria labyrinthiformis exhibits greater disease resistance than Pseudodiploria strigosa, making it a key model for studying coral disease resistance.

Purpose of the Study:

• To investigate the bacterial communities of Diploria labyrinthiformis and Pseudodiploria strigosa.
• To compare coral microbiome stability and composition under natural environmental fluctuations and experimental stress conditions (thermal and pH manipulation).
• To identify potential microbial factors contributing to the differential disease resistance observed between the two coral species.

Main Methods:

• In situ sampling of coral bacterial communities from the Florida Reef tract every six months for 18 months.
• Laboratory experiments involving manipulation of temperature (31°C) and pH (7.7) to simulate environmental stressors.
• Analysis of bacterial communities using operational taxonomic units (OTUs) to assess species-specific microbial composition and stability.

Main Results:

• Coral bacterial communities were similar in winter but diverged in summer, with D. labyrinthiformis showing greater microbiome stability than P. strigosa.
• D. labyrinthiformis harbored a distinct microbiome, with 29 specific operational taxonomic units (OTUs) across all seasons, compared to only 2 for P. strigosa.
• The stability and specificity of the D. labyrinthiformis microbiome were observed under both in situ and experimental conditions.

Conclusions:

• The comparative stability and specificity of the coral microbiome may play a crucial role in disease resistance.
• D. labyrinthiformis's ability to maintain a consistent bacterial community, even under stress, likely contributes to its higher resistance to disease.
• These findings highlight the importance of coral-associated microbial communities in coral health and resilience to environmental change.