Description: A 9-month aquarium experiment with the cold-water Dendrophyllia cornigera was conducted to investigate the single and combined effects of warming, acidification and deoxygenation on its ecophysiological response. The experiment took place at the Aquarium finisterrae (A Coruña, Spain) between 2022-05-06 and 2023-02-24. Treatment values for each parameter (current in situ vs. climate change) were: 12 °C and 15 °C (temperature); ~7.99 and 7.69 (pH); ~8.63 mg/L and 6.45 mg/L (dissolved oxygen concentration). A total of eight treatments (with 3 replicates each, 5 L aquaria) were set up. Measurements for pH and total alkalinity (TA) were performed on seawater samples from all the experimental aquaria every 1 – 2 months. Samples for pH were directly collected on cylindrical 10 cm cuvettes and analysed on daily basis. After being thermostated at 25ºC, samples were measured using a manual spectrophotometrical procedure with a Sigma Aldrich impure indicator (Clayton and Byrne, 1993). TA was measured following the double end point potentiometric technique by Pérez and Fraga (1987a) and Pérez et al. (2000). Measurements of Certified Reference Material (Dickson's lab, SIO) were performed in order to control the accuracy of the TA measurements. The uncertainty of TA and pH is about 3 μmol/kg and 0.005 pH units, respectively. In situ additional CO2 system variables were calculated using the R package seacarb (Gattuso et al. 2023) using in situ temperature, salinity, measured pH and TA, the dissociation constants of carbonic acid in seawater (K1 and K2) by Lueker et al. (2000), the equilibrium constant of hydrogen fluoride by Perez and Fraga (1987b), the concentration of total boron by Uppström (1974) formulation, and the stability constant of hydrogen sulphate by Dickson (1990). Mean values for the concentration of silicate and phosphate on the aquaria experiments were used in the CO2 calculations, respectively, mean (and standard) deviations as 2.1 (0.4) and 0.31 (0.03) μmol/kg.

Description: Water column raw data using the ship's own Kongsberg EM 122 multibeam echosounder was not continuously recorded during RV METEOR cruise M122. Data was recorded on 10 days between 2015-12-31 and 2016-01-27. The data are archived at the Federal Maritime and Hydrographic Agency of Germany (Bundesamt für Seeschifffahrt und Hydrographie, BSH) and provided to PANGAEA database for data curation and publication. Ancillary sound velocity profiles (SVP) files from the cruise are archived at the BSH and added to the corresponding multibeam raw dataset https://doi.org/10.1594/PANGAEA.945013 This publication is conducted within the efforts of the German Marine Research Alliance in the core area 'Data management and Digitalization' (Deutsche Allianz Meeresforschung, DAM).