Examining the successional role of Montipora aequituberculata on remote, post-disturbance equatorial reefs

Corals are dying globally at unprecedented rates and scales, and we are fast losing our ability to study the ecological dynamics of healthy, successionally mature reef communities. Insight into species-specific competitive dynamics is a necessary tool for assessing reef growth patterns and trajectory. Based on terrestrial successional frameworks, it is currently assumed that fast-growing corals catalyze post-disturbance regrowth and are eventually replaced by competitive, slower-growing species. To test this hypothesis, we assessed the fate of a dynamic, fast-growing, common Pacific coral, Montipora aequituberculata , through photogrammetric analysis of repeated large-area imaging. We used this technology to track ~600 colonies across 6 equatorial islands spanning 2 time points, examining whether colonies of M. aequituberculata were more typically overgrown by other species or able to maintain space and prevent overgrowth by other taxa. To accomplish this goal, we examined temporal dynamics from past-to-future and future-to-past, a new approach for addressing these questions. We found that M. aequituberculata colonies are competitively dominant against ruderal and other competitive taxa but will yield space to stress-tolerant taxa on post-disturbance reefs. Interestingly, we found that M. aequituberculata ’s island-scale interaction patterns—whether colonies successfully overgrew or were overgrown by other benthic taxa—did not necessarily correspond with M. aequituberculata ’s island-scale growth or loss patterns, highlighting local, site-level ecological complexity. Detailed examination of species interactions across spatial scales helps provide a mechanistic understanding of benthic community changes. Understanding and predicting these changes is useful for projecting reef recovery patterns, paving the way toward improved ecological interventions in a changing world.