Pioneer generation shapes long-term recovery of coral populations

Reef recovery following a disturbance largely depends on successful coral recruitment and the absence of chronic stressors. However, recent recovery events show increasing homogenization, with dominant coral species replacing the high diversity that once characterized these ecosystems. In this study, we analysed a nine-year dataset (2012–2020) describing the recovery of a reef towards a Pocillopora -dominated state in Taiwan following a devastating typhoon. Tracking eight coral cohorts, we assessed growth, survival and reproduction. Pocillopora recruitment peaked during the first three years, but mortality surged in the fourth year. The initial generation had the highest survival rates, while by the fifth year, newly settled individuals failed to survive beyond two years. By 2020, 83% of the reef consisted of corals from 2012–2016, with 38% originating from the first generation alone (2012). This pioneer generation was the primary contributor to growth and reproduction, emphasizing the reef's reliance on early settlers, leading to an ageing coral community. While pioneer generations were critical to recovery, their dominance may have driven a gradual loss of biodiversity. Our findings highlight the importance of early recruitment in reef development but underscores the risk of reliance on only a few species during and after recovery.