Fig. 2

Boxplots of the proton ([H⁺]) boundary layer thickness (µm; Eqs. 1, 2) in both coral species, Montipora capitata (a) and Pocillopora acuta (b). Box color distinguishes treatment (Control = ambient, ↑pCO₂ = ocean acidification), and the shaded region distinguishes light from dark conditions. Values are represented as individual profiles, with points, and the first and third quartiles are shown as boxes, with the median and whisker lines indicating the minimum and maximum. Significant differences are denoted as letters below the x-axis.