Temperature treatments
After the acclimation period, twelve coral nubbins (6 from each reef zone) were exposed to a high temperature treatment (29°C ± 1°C), while the remaining were maintained at ambient conditions (control, 25°C ± 1°C). Temperature was gradually increased from ambient to heat conditions over two days then maintained within the target range. The indoor temperature-controlled tank system consisted of two fiberglass trays fed from a common header tank of filtered seawater. Each tray table was temperature controlled by aquarium chillers and heaters. Light intensity was controlled by aquarium lights (Storm and Storm X LED Controllers, CoraLux LLC) on a 12:12h photoperiod. Temperature was measured every 5 minutes throughout the experiment by pairs of HOBO data loggers (Onset Corp.) placed in each tray table and light intensity was measured by a LiCor PAR sensor.