Mortality and recovery rates of Acropora fragments on in-situ nurseries after the 2023 bleaching event in the Turks and Caicos Islands

Abstract The present study assesses the mortality or recovery of Acropora cervicornis and Acropora palmata coral fragments on in-situ ocean nurseries during the fourth global coral bleaching event, 2023–2024. Once primary reef-building corals of the Caribbean and tropical western Atlantic, A. cervicornis and A. palmata are now critically endangered species. Population management in the region has been attempted with in-situ and land-based nurseries using the coral gardening restoration concept. However, ocean nurseries are not immune to environmental stressors, and the South Caicos, Turks and Caicos Islands, nursery sites experienced 81.1% mortality during the unprecedented marine heatwave. A. cervicornis had a higher mortality rate (94.2%) than A. palmata (74.7%), and the deepest nursery site at 12.1 m depth had the lowest mortality rate at 54.8%. Further, mortality rates did not differ significantly by nursery structure type. Findings suggest that deeper nurseries are more favorable for coral recovery and survival during heating events, providing restoration practitioners with a method of nursery protection as climate stress continues to intensify for coral reefs.