DOI: 10.5061/dryad.73n5tb2tc
title: Higher thermal resistance of corals in the global marine biodiversity center

description: Predictions for the future of coral reef are largely based on thermal
 exposure and poorly account for geographic variation in biological
 sensitivity and resistance to thermal stress. Based on the ratio of
 thermal exposure and sensitivity, geographic variability of coral
 resistance was estimated during the 2016 global-bleaching event. Exposure
 was estimated as historical cumulative excess summer heat (CTA) and a
 multivariate index of SST, light, and water flow (CE). Site sensitivity
 was estimated for 226 sites using coordinated bleaching observations. Site
 resistance was evaluated by 128 possible models for the influences of
 geography, historical SST variation, coral cover, and number of coral
 genera. Most factors were statistically significant but the strongest
 factor was geography - Coral Triangle having higher resistance than
 non-Coral Triangle sites. Consequently, future predictions of thermal
 stress will need to account for strong geographic differences in
 acclimation/adaptation.
description: The data are field observation on coral bleaching at the genus
 level and the associated environmental data at the time of the sampling. 
  This is the raw data.  For each survey, we calculated
 two standard bleaching metrics: (1) the percentage of bleached coral
 colonies, and (2) bleaching intensity, a weighted average of the relative
 abundance of coral colonies within each category of bleaching severity
 (Fig. 1b): 〖Bleaching intensity〗_ =
 (((0×c0)+(1×c1)+(2×c2)+(3×c3)+(4×c5)+(5×c5)+(6×c6)))/7
 Both metrics of bleaching produced similar results, and both
 provide simple, repeatable, and comparable methods to quantify bleaching.
 We chose the intensity metric for further analyses as it is separated
 sites across a wider bleaching gradient and resulted in better
 distinctions for modelling. On each survey, we evaluated total bleaching
 intensity across all coral colonies. Between March and
 September 2016, we conducted 235 bleaching surveys in 12 countries across
 the Indian and Pacific Oceans using a standard rapid roving observer
 methodology. To evaluate how survey timing was related to accumulated
 temperature stress, we extracted daily 5 km Degree Heating Week time
 series from NOAA Coral Reef Watch for each site from 1 September 2015 to
 the date of survey and calculated the date of maximum observed DHWs for
 each site. Based on these satellite temperature time-series, 45 sites did
 not experience excess heating (i.e., 0 DHWs). For the remaining 190 sites,
 we calculated the number of days between the date of the bleaching survey
 and the date of maximum DHW. For 181 sites, bleaching surveys occurred
 within 21 days of maximum DHW, well within suggested timelines to assess
 bleaching-related stress and mortality for corals (~30 days31). Nine sites
 where bleaching surveys were assessed &gt;21 days after maximum DHW
 were excluded from further analyses, leaving 226 sites across 11 countries
 for further analysis. Further details on study reefs and bleaching notes
 are provided in Supplementary Table 1.
description: The data are frequency information on the sites, the
 environmental variables, and the percentage of bleached corals in
 different bleaching categories.