<div>On days 62-65, respirometry measurements were performed. Two 260 ml cylindrical Perspex chambers were used. Chambers were filled with filtered seawater (0.25µm) at the temperature and CO2 concentration of the treatment relevant to each coral nubbin. Chambers were immersed in a water bath with temperature controlled to 25 ℃ or 29.8℃ (F500 Recirculating Cooler, Julabo). Magnetic stirrers circulated the water in each chamber. Each nubbin was incubated for ~15mins in the dark, exposed to light (using Sol LED lamps at peak irradiance of the relevant treatment) for ~10min, and exposed to darkness again for ~10 min. Intra-chamber oxygen concentrations were determined with a Fospor fibre optic probe (Neofox Oxygen Sensing System, Ocean Optics) at a 1 second logging interval. In trials, chamber illumination by the LED lamps caused interference with the probe’s ability to measure dissolved oxygen; this was resolved by shading the probe tip with an open-ended brown eppendorf tube and minimising light reflectance from the chamber base with black tape. <br></div>