Internal pH measurements made in the extracellular calcifying medium (ECM), calcifying (calicoblastic) epithelium and mesoglea of the coral Stylophora pistillata using the fluorescent dye SNARF-1 and confocal microscopy. The measurements were made in light and darkness three experiments. Experiment 1 involved using coral samples maintained at pH 8 seawater. Experiment 2 involved placing samples in 4 seawater acidification conditions: pH 8, 7.8, 7.4 and 7.2 for 1 week. Experiment 3 involved placing samples in 4 levels of dissolved inorganic carbon concentration: elevated; ambient, low and very low for one week. The research was carried out at the Centre Scientifique de Monaco between 2014-2017. The aim of the experiment was to determine the pH gradient across the calcifying cell layer and determine how it responded to the three experiments.

The experiments were done in the lab on coral samples that have been held in culture in Monaco for the last 30 years. The data file contains pH data from 3 experiments. In experiment 1corals were kept at seawater pH 8. In experiment 2. Corals were exposed to seawater acidification. In experiment 3 corals were exposed to manipulated DIC concentrations. The data are pH measurements taken from 3 internal compartments of the coral Stylophora pistillata: the mesoglea, the calcifying cells and the ECM.