Monthly heat over annual survey intervals gave no clear coral-cover link in four Atlantic and Pacific samples in 1998-2019

We tested whether heat over annual survey intervals had a negative link to hard-coral cover change. HeatCRD and NOAA OISST gave 1,010 matched pairs at 370 sites in 31 countries in 1998-2019. We matched site, source, month and depth. The heat index sums positive monthly SST excess above the local 1982-2011 maximum monthly normal plus 1 C. Four ocean and period models controlled initial cover, depth, year, month and source. All four country-cluster, four-test intervals include zero. Slopes per 0.1 C-month were +0.41 and -0.08 in the Atlantic, and -1.38 and -0.55 in the Pacific. Of 96 pairs with positive interval heat, 78 had zero final-month heat. Yet only two countries supplied positive heat in each Atlantic period. Thus survey-month heat missed much interval heat, but the interval model did not establish a repeated cover-change link. Sparse follow-up, few exposed countries, monthly surface temperature, source selection and missing observer logs limit inference. This result does not show heat safety or identify a causal climate effect. Pollution was not tested. The package gives code, aggregate results, exact sampled public-domain NOAA values, source hashes and independent checks. Biological records remain external.

coral cover · monthly heat · marine heat · exposure timing · observation bias · regional replication · uncertainty · HeatCRD