Abstract
Despite their immense importance, coral reefs worldwide are declining under pressure from multiple environmental and anthropogenic stressors. In order to preserve the ecosystem services that coral reefs provide, scientists are testing diverse strategies to make corals become more "climate smart." By modifying their association with endosymbiotic algae in the family Symbiodiniaceae, corals might be able to respond and adapt to changing environmental conditions. Although methods to manipulate adult corals have been well-studied, processes that regulate symbiosis establishment are less understood for early life stages. As climate change alters the ocean, it is important to study how biotic and abiotic factors may influence shifts in corals's algal symbiont communities throughout reefs and across generations, whether symbiosis can be harnessed as an intervention strategy to improve outcomes during early ontogeny, and how these shifts might impact reef persistence and resilience.
This dissertation takes a broad approach at investigating mechanisms of resilience in Caribbean coral recruits. I investigated (1) abiotic and biotic factors that mediate the uptake and/or selection of Durusdinium by previously aposymbiotic coral recruits; (2) physiological and competitive trade-offs of hosting different symbiont types during early ontogeny; (3) whether intentionally boosting Durusdinium abundance in recruits used for restoration proves advantageous during changing ocean conditions; (4) how stony coral tissue loss disease (SCTLD) impacts coral recruits; and (5) the degree to which symbiont metacommunities on Florida's reefs may have already shifted due to climate change. My goals are to investigate processes that influence survival and fitness in Caribbean coral juveniles, elucidate environmental factors that regulate symbiosis establishment, test methods of increasing thermal tolerance to reduce post-settlement mortality, and identify potential intergenerational feedbacks that may drive coral symbiosis ecology in the Caribbean.