Understanding how corals survive stressful conditions has never been more important given the number of people relying on reefs and the increasing threat of mass-bleaching events. While coral reefs worldwide face unprecedented environmental change, some corals can already be found living under the extreme conditions of marginal habitats. Learning how corals can survive the high temperature fluctuations and low pH conditions of mangroves (relative to typical reefs) could hold the key to ensuring coral survival into the future. To complicate matters, corals are not one organism but a meta-organism comprising animal host, symbiotic algae and diverse microbiota, known collectively as the ‘holobiont’. The roles of the various holobiont members, and how changes in their composition interact with environmental change to affect coral survival, remain unclear. My PhD research aims to determine whether changes in microbial symbionts enable corals to adjust to their environment – an idea termed the “coral probiotic hypothesis”. To address this, I have reciprocally translocated corals between mangrove and reef habitats surrounding Operation Wallacea’s Hoga Island Research Station, and will assess the coral-associated microbial communities using next-generation sequencing techniques. If the microbiome is important in influencing the adaptive capacity of a coral holobiont then the composition of the microbiome should be specific to the local environment and conform following transplantation.