The Changing Carbonate Chemistry of Coral Reefs: Implications for the Future of Reef Formation

Coral reefs are thought to be some of the most susceptible ecosystems to ocean acidification (OA), as OA is expected to have potentially drastic effects on their health and rates of accretion. Physical uptake of anthropogenic CO2 is the dominant driver of OA in the surface waters of the open ocean. However, multiple processes can influence the pCO2 of coastal ecosystems, potentially masking or amplifying the effects of increasing atmospheric CO2. A compilation of data from the literature indicates that the average pCO2 of coral reefs has increased ~3.5-fold faster than in open ocean surface waters within the past 20 years. This increase is most likely driven by a complex combination of anthropogenic disturbances to the balance of coral reef metabolism (i.e. photosynthesis and respiration). Modelling and a case study examining the influence of groundwater on short-term carbonate chemistry variability in two coral reef lagoons will be used to demonstrate potential agents of change to coral reef pCO2. Increasing average pCO2 in coral lagoons and reef flats may have broad implications to the formation and future sustainability of coral reef ecosystems