Water parameters during the experiment.

Temperature and pH were measured daily; salinity, dissolved inorganic carbon (DIC) and alkalinity were measured weekly beginning on the second week of the exposure period; all other parameters were calculated. Values are mean ± standard deviation, calculated across replicate tanks per treatment (N = 430 for pH and temperature, and N = 53 for other parameters). See S1 Fig for water parameter time-series and S1 Table for per-tank means.