Great Barrier Reef coral recovery did not stay low after 2012: disturbance-free growth on AIMS manta-tow reefs fell from 1985–1999 to 2000–2012, then rose above both in 2013–2025

Ortiz et al. (2018) reported an 84% decrease in Great Barrier Reef (GBR) coral recovery rates from 1992 to 2010. We did an out-of-sample test of this claim with AIMS Long-term Monitoring Program manta-tow estimates of reef-level hard coral cover (480 reefs, 3,844 reef-years, 1985–2025). For each pair of consecutive surveys of a reef (0.6–2.6 years apart), we calculated the annual log growth of cover. We kept only intervals without heat stress (NOAA Coral Reef Watch annual maximum DHW below 4) and without a cyclone (no IBTrACS point with 48 kt or more within 100 km). These external data, not the coral data, selected the intervals. A regression on log starting cover and shelf gave the growth at 10% cover. Reef-bootstrap 95% intervals are given. Growth was 0.150 ln/yr (0.125–0.180) in 1985–1999 and 0.090 (0.068–0.116) in 2000–2012, a 40% decrease. But in 2013–2025 it was 0.237 (0.197–0.283), higher than in both earlier periods. A linear trend fitted to 1985–2012 underpredicted 2013–2025 growth by 0.166 ln/yr (0.115–0.217). The increase occurred in the northern and central GBR. In the south, growth returned to its 1985–1999 level. The result stayed the same with reef fixed effects, annual intervals only, a fixed panel of 55 reefs, sector effects, low starting cover, terms for disturbance legacy, and quantile regressions on all intervals with no filter. With the strictest filter, 2013–2025 was higher than 2000–2012 but not clearly higher than 1985–1999. The share of intervals with heat or cyclone exposure increased from 16% to 67%. Thus recent coral loss agrees with more frequent disturbance, not with a continued loss of recovery capacity. Limitations: no per-reef crown-of-thorns starfish data were available (a far-northern subset with few outbreaks shows the same increase); manta-tow cover is a reef-wide measure, not coral-group recovery at fixed sites; few disturbance-free intervals exist after 2016. Code, exposure tables, hashes of the raw inputs and all estimates are included.

coral reefs · Great Barrier Reef · recovery rate · hard coral cover · AIMS Long-term Monitoring Program · manta tow · degree heating weeks · tropical cyclones · out-of-sample test · disturbance regime · resilience · crown-of-thorns starfish