UC San Diego

Coral reefs represent one of the most productive ecosystems in the world, fostering immense biomass and biodiversity. Local disturbances, global climate change and poor recruitment are causing coral reefs to decline at prodigious rates. Variability in response to these stressors at a local level makes management and reconstruction of coral reefs challenging. For example, reef managers lack the ability to accurately predict the relative stress and the reef-specific response to the increased heating caused by global climate change as this can be dictated by the endosymbiont variability, bleaching history, flow dynamics and microbial community composition. Similarly, reef reconstruction efforts remain ineffective as worsening environmental conditions are driving lower levels both recruitment of coral larvae and survival of the new recruits. These environmental fluctuations are accompanied by large changes in the composition and concentration of the dissolved organic matter (DOM) pools of coral reefs. Marine DOM represents a complex, mostly unidentified assemblage of molecules, the dynamics of which have been linked to changes in the ecological functions of the benthic community such as the overgrowth of calcifying constituents by fleshy algae via a DOM and microbe-mediated process. However, limited characterization of reef DOM pools in the face of these challenges diminish the potential for adequate management and reconstruction of reefs. The goal of this dissertation is to further characterize the reef-derived dissolved organic matter pools which underpin the survival, stress-response and settlement of reef building coral holobionts.