Current bleaching gave no clear next-year cover-loss link in matched Atlantic and Pacific coral records, 2003-2018

We tested whether current bleaching predicted next-year hard-coral cover change in Reef Check records matched by site, calendar month, and depth band from 0 to 15 m. We used current years 2003-2018 and follow-up through 2019 in the Atlantic and Pacific. The analysis had 1,286 complete pairs at 560 sites in 36 countries. The adjusted estimate was -0.81 cover percentage points per 10 points of current bleaching. The country-cluster 95% interval was -1.87 to +0.26 points. All four ocean-period intervals included zero. Only 14.7% of eligible current cells formed complete pairs, and only 70 pairs had mean bleaching of at least 10%. These records gave no clear link that repeated across regions and periods under this design. They permit a loss of practical size and do not show that bleaching has no biological effect. Selective follow-up, survey error, heat timing, and few high-bleaching pairs limit inference. The package preserves derived records, source hashes, code, numerical checks, and a figure. It does not estimate mortality, species loss, or air pollution effects.

coral bleaching · hard coral cover · marine heat stress · observation bias · lagged response · Reef Check