The AOAT project is engaged in monitoring/modeling efforts designed to: a) establish methodologies for monitoring, assessing, and modeling the impacts of Ocean Acidification (OA) on coral reef ecosystems, b) identify critical thresholds, impacts, and trends necessary for developing forecasts, c) characterize the variability in carbonate chemistry in coral reef environments, and d) provide data and information needed to inform ecological impact forecasting. Existing projections of OA on coral reef ecosystems (e.g. Silverman et al., 2009) make a core assumption that secular declines in carbonate mineral saturation state (O, a key parameter of OA interest) are equivalent to those experienced in the oceanic surface waters. Sustained observations at the AOAT, however, reveal considerable complexity and diverge from neighboring oceanic waters during most periods. Seasonal ranges in O-values exceed those anticipated as aconsequence of OA over the next several decades. Complexities within near-reef waters are likely the norm and we seek to better model the primary controls on near-reef carbonate chemistry. The AOAT has served as a critical venue to foster research from other agency and academic partners towards the development of techniques which can be applied to monitor OA within reef environments and quantify the local feedbacks that can alter rates and magnitude.