What is Aragonite Saturation and Why is It Important? Aragonite (a specific form of the calcium carbonate mineral) saturation state is a measure of how much calcium and carbonate are in seawater. It indicates the availability of dissolved electrically charged atoms (ions) in sea water for marine organisms, like corals and shellfish, to build their shells and skeletons (calcified structures). A lower aragonite saturation state (less than or equal to a value of one) makes it harder for these organisms to build and maintain their calcified structures. Low aragonite saturation state can often be a result of low pH. From a water quality and resource management perspective, pH can be regulated and managed, such as through water quality management programs that help regulate the chemicals coming from the land that impact coastal pH; however, calcium and carbonate ions can not be directly controlled. It is still important to understand the relationship between aragonite saturation state and pH to help us understand how organisms are affected by acidic conditions.