Abstract
Coral reefs are among the most ecologically significant and biologically diverse ecosystems on the planet, providing habitat for countless marine species, protecting coastlines, and supporting the economies and food security of millions of people. Yet they are undergoing rapid declines due to anthropogenic stressors that promote coral disease and shifts toward microbe- and algae-dominated reef states. At the core of reef function and resilience is the coral holobiont: the coral animal and its associated community of microorganisms, including bacteria, archaea, fungi, protists, and viruses.
Among the microbial constituents of the coral holobiont, bacteriophages, viruses that infect bacteria, are especially understudied despite being fundamental to microbiome dynamics across virtually every ecosystem. They are the most abundant biological entities on Earth and shape microbial communities by lysing bacterial populations, mediating horizontal gene transfer, and altering host function through lysogeny. Despite growing recognition of the microbiome's central role in coral health and stress response, the viral dimension, particularly bacteriophages, remains largely unexplored in coral reef research. This gap reflects both the complexity of host-associated microbiomes and the immense diversity of viral genomes.
This dissertation explores how environmental phages influence microbial community dynamics within coral holobionts and how these interactions may scale to affect coral health and resilience.