This dataset includes pigment concentrations of the coral species Porites astreoides and Montastraea cavernosa from Bermuda that were exposed to a temperature reduction experiment for 37 days. Prior to the experiment, 8 corals were collected with a hammer and chisel on 16th June 2019 in 5 m depth at Sea Venture Shoals, Bermuda [32º22'53” N, 64º38'11” W], which is an exposed reef featuring a typical Bermuda reef community. Water temperature during collection was ~27°C. The seasonal temperature range of Bermuda reefs is ~19°C to 29°C. The laboratory-based experiment took place at the Bermuda Institute of Ocean Sciences from 1st July to 6th August 2019 and used flow-through seawater from the adjacent Reach. Light was provided by Indoor grow lights, Sun Blaze T5 Fluorescent 44. The successive treatments were: (i) constant control temperature at 28°C, and (ii) temperature reduction (0.5 °C/day) followed by constant temperature for 20 days at 24 °C and (iii) temperature reduction (0.5 °C/day) followed by constant temperature for 20 days at 20 °C. Tissue metrics were measured on day 1, 17 and 37 of the experiment including various photosynthesis related pigments. Light-harvesting/photo-collecting (chlorophyll a, peridinin and chlorophyll c2) and photo-protective pigments (diadinoxanthin and diatoxanthin) were determined with a high performance liquid chromatography Agilent 1100, Agilent Technologies, Germany and standardized to coral surface area.

Sample IDs indicate species (M=Montastrea cavernosa, P= Porites astreoides), the replicate ID (1 to 8; each replicate is a different coral colony) and the fragment ID (A-G; each coral colony was divided into 7 fragments).