Spatio- temporal juvenile corals (Scleractinia) following the 2016 coral bleaching event at the Pieh Islands Marine Tourism Park (PIMTP), West Sumatra Province, Indonesia

Juvenile corals and their spatio-temporal changes are essential predictors in assessing the recovery of coral reef after disturbances, including by coral bleaching. To gain a deeper understanding, we conducted observations of juvenile corals before and after the 2016 coral bleaching event and their relationship with reef-associated biota at ten permanent monitoring sites in the Pieh Islands Marine Tourism Park (PIMTP), West Sumatera, Indonesia. Our study reveals a decrease in the abundance of juvenile corals following the 2016 bleaching, amounting to approximately 26%, primarily affecting juveniles of Montipora, Acropora, and Pocillopora, with no significant changes observed. The dominant juvenile corals, Montipora, Pocillopora, and Acropora, before the bleaching event were replaced by Pavona and Porites, which persisted and increased post-bleaching. While several genera were not found, new genera emerged. Despite these changes in species composition, species diversity remained unaffected. Although an increase in the abundance of juvenile corals correlated with live coral cover, the correlation was low and negative. The presence of algae as niche competitors exhibited a different correlation compared to previous studies and did not impact coral juveniles significantly, with herbivorous reef fish showing a reasonable control effect. Rubble, serving as a substrate for larval settlement and a micro-habitat for juvenile coral development, exhibited a negative correlation. Our research delineates the temporal changes in young coral populations pre and post the 2016 coral bleaching event. These findings contribute to the scientific understanding that juvenile coral serves as a critical predictor of coral reef resilience and recovery from bleaching, emphasizing its implications for coral reef conservation.