Dataset: Results of the quantification of symbiont cell numbers from 400 Acropora hyacinthus colonies subjected to experimental bleaching in the summer of 2018 in Palau.

The samples that were analyzed for this study are 400 colonies of Acropora hyacinthus. Nubbins from each colony were experimentally bleached at temperatures of 34, 34.5 and 35 degrees Celsius as well as two control treatments (30 deg. C). Experimental bleaching treatments lasted for 3 hours a day for 2 days (a total of 6 hours). Nubbins from each colony were assessed at the beginning of the experiment before bleaching stress (Day 0), as well as on the subsequent 2 days. Tissue from each colony was preserved for later analysis.

Colonies were sampled from 40 reefs (10 colonies per reef) across the Palauan archipelago. These colonies are tagged and their locations are recorded by GPS. We sampled each colony using garden clippers to break off 5 nubbins that we transported back to the Palau International Coral Reef Center where they were subjected to the experimental procedures outlined above.