Coral Bleaching and Marine Protected Area Protection (2002–2017)

This global survey dataset (9,501 observations × 19 variables) from Zenodo #7029064 examines coral bleaching events in relation to Marine Protected Area (MPA) coverage, sea surface temperature anomalies, and human population pressure. The core thermal stress metric — Degree Heating Weeks (SSTA_DHW) — has a median of just 1.22 but spikes as high as 38, with 141 statistical outliers, revealing that bleaching-level heat stress is geographically concentrated rather than uniformly distributed across reef sites. Perhaps the most striking pattern is the extreme range in nearby human population density: reef sites sit in areas with anywhere from zero to 35.5 million people within 100 km (median ~454K), and human population counts at the 25 km, 50 km, and 100 km radii are all strongly correlated (r²=0.78–0.90), suggesting that coastal urbanization clusters persistently around reef ecosystems worldwide. Sea surface temperatures span 292–307 K (~19–34 °C) across sites, capturing both healthy and critically warm reef environments. Together, the data allow researchers to disentangle whether MPA designation genuinely buffers corals against bleaching, or whether local human pressure and thermal anomalies overwhelm any protective benefit.

• MPA sites consistently show higher bleaching rates than non-MPA sites — 39% of MPA surveys detected bleaching vs 30% for non-MPA
• The 2016 global bleaching event hit MPAs hardest: average bleaching in protected areas spiked to 44%, the highest in the 16-year record
• Heat stress is the dominant driver — sites with 8+ Degree Heating Weeks show 27% average bleaching, 4× higher than unstressed sites
• Caribbean regions (BVI 67%, Belize 25%, Jamaica 22%) are the most severely affected, far exceeding the global average of 10%
• Depth provides no refuge: bleaching rates are nearly identical from 0–5m (10.2%) through 10–20m (10.8%)