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The data included in this data package were collected in the lagoon of Moorea, French Polynesia. Data on coral mortality were collected in July 2019. Data on nitrogen content (%N) in the long-lived brown macroalga Turbinaria ornata were collected during six sampling campaigns between January 2016 and May 2021 to characterize nitrogen availability at each site. Data on seawater temperatures at six LTER sites in the back reef were collected from 2005-2019, but temperature loggers at two sites (LTER 1 and LTER 6) only recorded partial ocean temperature records during the heatwave from 2018-2019. We used our entire time series (spanning from 2005 to 2018) of temperature across our four long-term sites for which we have data in 2019 to predict ocean temperature data for LTER 1 and LTER 6 in 2019. These data were used for analyses in the manuscript entitled "Effects of nitrogen enrichment on coral mortality depend on the intensity of heat stress". 

Abstract Marine heatwaves are increasing in frequency and duration, threatening tropical reef ecosystems through intensified coral bleaching events. We examined a strikingly variable spatial pattern of bleaching in Moorea, French Polynesia following a heatwave that lasted from November 2018 to July 2019. In July 2019, four months after the onset of bleaching, we surveyed > 5000 individual colonies of the two dominant coral genera,PocilloporaandAcropora, at 10 m and 17 m water depths, at six forereef sites around the island where temperature was measured. We found severe bleaching increased with colony size for both coral genera, butAcroporableached more severely thanPocilloporaoverall. Acroporableached more at 10 m than 17 m, likely due to higher light availability at 10 m compared to 17 m, or greater daily temperature fluctuation at depth. Bleaching inPocilloporacorals did not differ with depth but instead varied with the interaction of colony size and Accumulated Heat Stress (AHS), in that larger colonies (> 30 cm) were more sensitive to AHS than mid-size (10–29 cm) or small colonies (5–9 cm). Our findings provide insight into complex interactions among coral taxa, colony size, and water depth that produce high spatial variation in bleaching and related coral mortality.