Over the past four decades, benthic cyanobacterial mat abundance has increased significantly on many coral reefs worldwide. It however remains unclear what actually drives their current success, and how they impact the reef ecosystem as a whole. This PhD thesis presents a missing link that explains - via a mechanistic approach - the recent proliferation of benthic cyanobacterial mats. Results indicate that benthic cyanobacterial mats have a large impact on the functioning of the reef, especially via their vast N2 fixation capacity and release of dissolved organic carbon into the water column. Additionally, in comparison to other reef organisms, benthic cyanobacterial mats have very high nutrient uptake kinetics and high primary productivity rates. These characteristics likely contribute to their recent successfulness on the reef. This thesis furthermore suggests that nutrient and organic matter reduction is essential to prevent benthic cyanobacterial blooms from occurring on the reef
