Temporal dynamics of coral bleaching and live coral cover at the Cayman Crown Reef, Gulf of Honduras (2016–2025)

Located in the Gulf of Honduras between Guatemala and southern Belize, Cayman Crown (Corona Caimán) is a recently documented offshore coral reef system of high geomorphological complexity lying at the terminus of the deep Cayman Trench. The reef is characterized by extensive spur-and-groove formations and steep vertical walls descending from 10–30 m to depths exceeding 300 m. Despite its offshore location, Cayman Crown has historically supported among the highest live coral cover recorded across the Mesoamerican Reef (24-50%), consistently corresponding to good (≥20%) to very good (≥40%) live coral cover, under the Reef Health Index. However, the reef has been exposed to intensifying thermal stress across three successive bleaching events. It remains unknown whether this offshore reef can retain its capacity to recover under repeated thermal stress, as multi-event, site-level records of bleaching and recovery are lacking for this reef system. Here, we assess bleaching severity, mortality, and recovery across four sites spanning three bleaching events from 2016 to 2025. The highest Bleaching Severity Index (BSI) values were recorded during the 3.5 Regional Coral Bleaching Event (RCBE), 2019–2021; with a BSI of 54–59% and peak DHW ~10 °C-weeks, followed by the Fourth Global Coral Bleaching Event (GCBE), 2023–2025; with a BSI: 25–41% and peak DHW ~19 °C-weeks, and moderate values during the Third GCBE, 2014–2017; with a BSI: 25–30% and peak DHW ~8 °C-weeks. Following the 2019 bleaching, corals recovered nearly completely, demonstrating strong short-term post-disturbance resilience. In contrast, consecutive bleaching during the Fourth GCBE resulted in approximately 29% overall coral mortality and persistent residual bleaching extending into the February 2025 post-disturbance survey (BSI: 4–10%). The 2023–24 bleaching caused pronounced live coral cover losses, particularly at Corona Caimán Valle de Aga CC01 (50.3% to 34.1%) and Corona Caimán Bajón GT008 (35.7% to 22.5%), while Corona Caimán 2 CC02 showed a slight increase (24.7% to 28.3%), indicating variability in site-level responses. These findings are consistent with projections of increasing marine heatwave frequency, under which reefs would experience repeated bleaching with shorter recovery windows. The transition from near-complete recovery following a single acute bleaching disturbance to measurable colony mortality under consecutive bleaching events suggests that repeated heat stress may erode the resilience of even offshore reefs.