Accelerated recovery of calcium carbonate production in coral reefs using low-tech ecological restoration

•Outplanting corals of opportunity was an effective tool for long-term restoration.•Pocillopora spp. increased two and fourth-times in growth and ecological volume.•After five years of coral restoration, coral cover and carbonate production doubled. Ongoing climate change and frequent anomalous thermal events have greatly contributed to the deterioration of coral reefs worldwide, exacerbating declines in coral reef formation and ecosystem service provision. Under this climate change scenario, the development and improvement of restoration techniques will be required to cope with coral reef degradation. This study demonstrates the potential use of direct relocation of coral of opportunity as an effective long-term ecological restoration tool. We assessed coral growth parameters (cm yr−1), attachment rate (%), ecological volume (cm3 yr−1), including long-term evaluation of annual live coral cover (%) and calcium carbonate production (kg CaCO3 m−2 yr−1) during 5-years (2013–2018) using resilient branching coral Pocillopora spp. The results show a survivorship of 67%, high self-attachment (100%) during the first 6-months, and size augmentation of ∼167% in growth parameters (2.94–4.47 cm yr−1) and ∼418% in ecological volume. Over the long-term, live coral cover increased from 13 to 28% (+4% per year) with an accumulated carbonate production of 14.53 kg CaCO3 m−2 (∼3 kg CaCO3 m−2 yr−1) resulting from the restoration process, and we found evidence for high resistance and recovery after periods of thermal anomalies. The data validate the use of direct propagation of corals of opportunity as a one of the most feasible and practical techniques to long-term restoration of damaged and degraded coral reef areas, which may help in their structural rehabilitation, improving coral communities and biodiversity maintenance.