Genetic and ecological exploration of the algal microbiome

correlated to changes in host condition. These results show that there is a need to consider the entire algal-bacteria ‘holobiont’ when investigating environmental impacts on seaweeds. Additionally, we evaluated the use of DNA-stable isotope probing for the investigation of bacteria associated to carbon metabolism in Caulerpa. Here we establish the viability of the technique and conclude that this is potentially an effective method for identifying key bacteria species involved in carbon uptake. Collectively, the results of the studies within this thesis contribute to a deeper understandingof the algal microbiome and the ecological impacts of environmental changes on host-bacteria interactions. Moreover, bacterial interactions with a host facilitate environmental adaptations that may have evolutionary implications and should be further investigated. These findings suggest that the algal ‘holobiont’ itself is more complex than previously described and a more definitive explanation needs to be developed to incorporate multiple levels of speciesinteractions and drivers.Public defense: 2019-09-20correlated to changes in host condition. These results show that there is a need to consider the entire algal-bacteria ‘holobiont’ when investigating environmental impacts on seaweeds. Additionally, we evaluated the use of DNA-stable isotope probing for the investigation of bacteria associated to carbon metabolism in Caulerpa. Here we establish the viability of the technique and conclude that this is potentially an effective method for identifying key bacteria species involved in carbon uptake. Collectively, the results of the studies within this thesis contribute to a deeper understandingof the algal microbiome and the ecological impacts of environmental changes on host-bacteria interactions. Moreover, bacterial interactions with a host facilitate environmental adaptations that may have evolutionary implications and should be further investigated. These findings suggest that the algal ‘holobiont’ itself is more complex than previously described and a more definitive explanation needs to be developed to incorporate multiple levels of speciesinteractions and drivers.D