The role of the microbiome in coral bleaching and disease: friends or foes?

Abstract

Reef-building corals form associations with both symbiotic algae and diverse communities of bacteria and archaea. Coral-associated bacteria serve a range of beneficial functions within the coral holobiont, providing nutrients to both host coral and algal symbiont and defending against pathogenic bacterial taxa. Coral-associated bacterial communities are highly diverse and responsive - varying with environmental conditions, host coral species, and holobiont health status. Indeed, shifts in the composition of coral-associated bacterial communities are widely observed in response to anthropogenic pollution and during incidences of coral bleaching and disease. However, the exact function of these bacterial communities within the holobiont is poorly understood, and their relative importance in different coral species is unknown. Furthermore, it remains unclear how disturbances in seawater macronutrient availability influence the taxonomic profile of prokaryotic communities in reef-building corals. Here, I use 16S rRNA gene sequencing to examine the effects of skewed nitrogen (N) and phosphorous (P) seawater stoichiometry (N:P) on the structure of the prokaryotic communities associated with symbiotic reef corals under controlled aquaria conditions. Firstly, my results reveal that imbalances in seawater N:P stoichiometry can significantly alter prokaryotic community composition and network topography in reef-building corals. Secondly, through comparative analysis, I characterise the differing physiological and prokaryotic community responses of two phylogenetically and morphologically divergent reef-building corals to skewed seawater nutrient availability. Finally, I examine the role of seawater N and P availability in the development and progression of coral diseases. My results demonstrate how coral-species specific changes in microbial community structure could contribute to the physiological response and tolerance of the host coral to changes in nutrient availability. By examining the response of coral-associated microbial communities to macronutrient availability, these results provide insight into how the coral holobiont will respond to anthropogenic influences and a changing climate.

More information

Identifiers

ORCID for Raphaela Lealan Gracie: orcid.org/0000-0002-4228-6970

ORCID for Phyllis Lam: orcid.org/0000-0003-2067-171X

Catalogue record

Export record