Exposure to wind and swell gave no clear heat buffer in six coral survey samples from 2003 to 2019

We tested whether exposed reefs had a smaller coral bleaching response to heat than sheltered reefs. We used 5,783 repeated Reef Check site-month records at 1,335 sites in three oceans from 2003 to 2019. The model controlled site, ocean-year, ocean-month and depth. The pooled exposed minus sheltered slope was -2.15 bleaching percentage points per four degree-heating weeks. Its nominal 95% interval was -5.37 to +1.08. All six ocean-period intervals included zero after correction for six tests. A same-calendar-month model and a region-year model also gave uncertain differences. A second heat measure gave a negative nominal interval, but it measured a different anomaly. Heat support was weak in the Indian Ocean. Selected visits, missing reports, broad site exposure classes and unknown coral composition limit inference. The result does not establish no effect, a causal climate effect, species loss or air pollution effects. The package includes code, a survey panel, source hashes, figures and independent numerical checks.

coral bleaching · heat stress · wave exposure · observation bias · regional replication