Bacterial Response to Elevated Dissolved Organic Carbon in Coral Reef Ecosystems

Coastal pollution and algal cover are increasing in many coral reefs, resulting in higher dissolved organic carbon (DOC) concentrations. High DOC concentrations are shown to have highly detrimental effects on coral reefs through the stimulation of bacterial growth and the accumulation of suspended particles (i.e., aggregate formation). In this thesis, aggregate formation processes and gene expression of planktonic coral reef microbial populations under elevated concentrations of naturally abundant monosaccharides (glucose, galactose,mannose, and xylose) in algal exudates and sewage inputs, were investigated. The results of this thesis show evidence of the detrimental effects of high DOC concentrations on coral reefs by promoting aggregate formation and microbial activity. Furthermore, this thesis shows that elevated DOC concentrations mediate the expression of virulence factors involved in invasion, iron chelation, accumulation of toxic substances, suggesting to be important for feeding the positive loop of coral reef degradation.