Demographic recovery of corals at a wave-exposed reef following catastrophic disturbance

Abstract

Rapid recovery of coral cover following acute disturbance has been documented on many reefs. Yet measuring coverage alone can mask shifts in community and demographic structure. Here, we quantify long-term changes in population size structure for three common genera (Acropora, Pocillopora, and Stylophora) at an eastern outer reef in Palau, Micronesia, following catastrophic loss of corals due to typhoon Bopha in 2012, based on size measurements from 3648 coral colonies. Mean colony size returned to pre-disturbance levels within 4 and 6 years for Stylophora and Pocillopora, respectively. By 2020, Pocillopora colony density far exceeded pre-disturbance levels, with rapid successful recruitment following typhoon Bopha. Despite recovery of Acropora colony density by 2020, populations remained dominated by smaller colonies. We demonstrate that full demographic recovery can occur more rapidly for pocilloporids (within 6 years) compared to Acropora which had not fully recovered by 8 years post-disturbance, possibly due to fewer annual recruitment events and larger maximum colony sizes. Our results highlight the value of demographic metrics as early indicators of recovery.