Table 1. Automated temperature recordings in experimental aquaria ca. every 5 minutes throughout the experiment (every 10 minutes during ambient recovery phase).

Temperature change refers to the rate of temperature decrease from ambient in the cold stress ’winter’ phase. Values are treatment averages of all recorded values (day and night) for each period from triplicate aquaria combined (mean ± standard deviation). Acclimation refers to the days corals were in experimental aquaria before onset of cooling. Winter refers to the 16-day cold stress experimental period at minimal temperatures (i.e. 28th March–12th April). Recovery: two months in ’common garden’ aquaria at ambient seawater temperature. Summer refers to acute heat shock (maximal temperature hold days) 11th–13th June. During the summer phase, fragments from all winter treatments were combined into three replicate heated aquaria with a common above ambient temperature.

Treatment	Temperature change (°C d−1)	Temperature (°C)
		Acclimation	Winter	Recovery	Summer
T0	−0.0	20.27 ± 0.37	22.42 ± 0.19	24.74 ± 1.28	29.93 ± 0.93
T-1	−0.3	20.70 ± 0.65	20.53 ± 0.46
T-3	−0.6	20.38 ± 0.45	18.61 ± 0.77