Disentangling the effect of host-genotype and environment on the microbiome of the coral Acropora tenuis

• Published in: PeerJ (San Francisco, CA) CA), 2019-02, Vol.7, p.e6377-e6377, Article e6377
• Main Authors: Glasl, Bettina, Smith, Caitlin E, Bourne, David G, Webster, Nicole S
• Format: Article
• Language: English
• Subjects: Acropora tenuis; Algae; Biological indicators; Coral microbiome; Coral reefs; Corals; Disease susceptibility; Endozoicomonas; Genes; Genetic research; Genotype & phenotype; Genotypes; Host-genotype specificity; Marine Biology; Microbial indicators; Microbiology; Microbiomes; Microbiota; Microorganisms; RNA; rRNA 16S; Salinity; Salinity effects; Seawater; Seaweeds
• ISSN: 2167-8359; 2167-8359
• DOI: 10.7717/peerj.6377

Genotype-specific contributions to the environmental tolerance and disease susceptibility of corals are widely accepted. Yet our understanding of how host genotype influences the composition and stability of the coral microbiome subjected to environmental fluctuations is limited. To gain insight into the community dynamics and environmental stability of microbiomes associated with distinct coral genotypes, we assessed the microbial community associated with under single and cumulative pressure experiments. Experimental treatments comprised either a single pulse of reduced salinity (minimum of 28 psu) or exposure to the cumulative pressures of reduced salinity (minimum of 28 psu), elevated seawater temperature (+2 °C), elevated CO (900 ppm), and the presence of macroalgae. Analysis of 16S rRNA gene amplicon sequence data revealed that microbiomes were highly host-genotype specific and maintained high compositional stability irrespective of experimental treatment. On average, 48% of the microbiome was dominated by Amplicon sequence variants (ASVs) belonging to this genus were significantly different between host individuals. Although no signs of stress were evident in the coral holobiont and the vast majority of ASVs remained stable across treatments, a microbial indicator approach identified 26 ASVs belonging to Vibrionaceae, Rhodobacteraceae, Hahellaceae, Planctomycetes, Phylobacteriaceae, Flavobacteriaceae, and Cryomorphaceae that were significantly enriched in corals exposed to single and cumulative stressors. While several recent studies have highlighted the efficacy of microbial indicators as sensitive markers for environmental disturbance, the high host-genotype specificity of coral microbiomes may limit their utility and we therefore recommend meticulous control of host-genotype effects in coral microbiome research.