CORAL MICROBIOME COMPOSITION AND DIVERSITY DURING INDUCED EX-SITU BLEACHING

Abstract

Coral-associated microbial communities contribute to the health, resistance, and resilience of corals toward thermal stress. However, little has been documented on the dynamic of coral microbiome and their shifts during and after bleaching. In this study, we discussed the comparative analyses of bacterial communities in four coral species (D. pallida, C. microphthalma, P. harrisoni, and P. daedalea) associated with different health status (healthy, paling, bleaching and mortality) during induced ex-situ bleaching using Oxford Nanopore Technology. Our findings showed that the bacterial community composition and diversity of coral species varied significantly across health status due to fluctuations in seawater temperature and their shifts are associated with coral heat stress. Four bacteria phyla were the most abundant phyla across all health status and for all coral species with variation in relative abundance, including Cyanobacteria, Proteobacteria, Firmicutes and Bacteroidota. There was an increase in α-diversity (sobs index; species richness) in bleached corals with the highest diversity in P. harrisoni. However, species richness and evenness (Shannon index) represented low diversity in all bleached corals, indicating dominant species and less biodiversity. C. microphthalma, P. harrisoni had higher β-diversity; more dissimilarities between healthy and unhealthy coral conditions. Overall, the induced bleaching influences the dynamic of bacterial communities and their composition and diversity across different health status.