The abundance and diversity of microbes in corals are indicative of an intricate coexistence between the metazoan host and these unicellular partners. An increasing number of studies identify explicit functions that microbes perform in the coral holobiont, ranging from nutrient cycling to immunity. Rapid climate change has known effects on reef-building corals, and can similarly affect microbial symbiosis – negative shifts in microbial community structure (i.e. dysbiosis) can lead to coral disease and mortality. Alternately, microbes may also contribute to holobiont resilience by rapidly adapting to new environmental regimes and may provide the coral with an uninterrupted suite of functions. To understand whether shifts in the microbiome as a result of environmental change will be positive or negative, we must identify what drives natural variations in community composition. This thesis is focused on investigating and identifying the drivers of microbial community composition in corals to help predict how corals may respond to environmental changes in the future, and to provide critical baseline data to inform the development of the microbial-driven restoration technique of microbiome engineering. All data chapters identify that both host mediation and environmental factors are crucial drivers of the coral microbiome. Thus, the ability of the microbiome to confer stress tolerance to the host under changing environmental conditions is likely species and location specific, and will therefore pose a challenge for implementing long-term microbial manipulations.
Hannah is a PhD Candidate at the ARC CoE for Coral Reef Studies in conjunction with the Australian Institute of Marine Science as part of the the joint venture AIMS@JCU. Hannah began her career in marine science at the University of St Andrews, after which she completed her Bachelor of Marine Science with Honours at James Cook University investigating the biomonitoring potential of jellyfish. Between finishing her honours and beginning her PhD, Hannah conducted phylogenetic and systematics research at the California Academy of Sciences, where she contributed to the description of several new species of nudibranch (sea slugs). With her new found interest in molecular work, she returned to Australia to complete her PhD in the microbial ecology of corals as part of a larger collaboration exploring potential avenues for the acclimatisation of corals to climate change.