Investigating responses of calcium carbonate nucleation rates in artificial seawater to changes in saturation states due to ocean acidification

Abstract

[author abstract] Reduced saturation states of carbonate ions caused by ocean acidification make it harder for marine calcifiers such as corals to build their shell or skeleton. Nucleation is vital to corals because it is a necessary precursor to the crystal growth that builds coral skeletons. This study examines changes in inorganic calcite nucleation rates over different carbonate saturation states as a first step to understanding aragonite nucleation and predicting how coral growth is affected by changes in acidity. To accomplish this, a temperature-controlled microscope flow-cell is used with time-lapse photography to compare nuclei densities at different saturation states. Inorganic calcite nucleation rates are sensitive to carbonate saturation states based on nucleation pathways and classical nucleation theory. These results extend existing data to low saturation states, which are considered to be more in the physiological realm of nucleation.