Respiration rates of the cold-water coral Dendrophyllia cornigera from a long-term multi-stressor experiment

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. Respiration rates from each nubbin (3 per aquarium) were assessed after 6 and 9 months under the experimental conditions by means of closed-cell incubations. Oxygen consumption was calculated by measuring the dissolved oxygen concentration of the seawater inside the chamber using an optical oxygen sensor (YSI ProODO) at the beginning and at the end of the incubation time (24 h incubation). Dry mass (g) of the coral nubbins was assessed by means of the buoyant weight technique (Jokiel et al. 1978, Davies, 1989), using an analytical balance (OHAUS AX124, precision 0.1 mg). Tissue surface area (cm2) was assessed on virtual 3D models of each nubbin at the time when the measurements were conducted. Respiration rates were normalised by dry mass and by tissue surface area.