This dataset contains data in support of Edmunds, P.J., S.S. Doo, R.C. Carpenter, 'Changes in coral reef community structure in response to year-long incubations under contrasting pCO2 regimes', Marine Biology, 2019, doi:10.1007/s00227-019-3540-2. Here, the effects of ocean acidification (OA) on back reef communities from Mo'orea, French Polynesia (17.492S, 149.826W), were tested from 12 November 2015 to 16 November 2016 in outdoor flumes maintained at various mean pCO2 levels. Change in mass and percent cover were recorded monthly. This material is based upon work supported by the U.S. National Science Foundation under Grant No. OCE 16-37396 (and earlier awards) as well as a generous gift from the Gordon and Betty Moore Foundation. Research was completed under permits issued by the French Polynesian Government (Délégation à la Recherche) and the Haut-commissariat de la République en Polynésie Francaise (DTRT) (Protocole d'Accueil 2005-2018). This work represents a contribution of the Moorea Coral Reef (MCR) LTER Site.