Skeletal growth 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. Dry mass of the coral nubbins (3 per experimental aquarium) 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). The dry mass was calculated considering the nubbin net weight in water, the water density and the skeletal density of D. cornigera (2.63 g/cm3; Movilla et al. 2014). Measurements were performed just once the acclimation time finished and after 2 , 4, 6 and 9 months under the experimental conditions. Skeletal growth rates were calculated as the slope of the linear regression between the logarithmically transformed dry mass and the experimental time (%/day) (Orejas et al. 2011).