Asexual reproduction in reef-building corals: insights into fragment attachment to improve restoration and predict natural recovery.

Coral reefs are experiencing global decline, and their recovery relies heavily on asexual reproduction through fragmentation, the success of which hinges on self-sustaining attachment to the reef substrate. However, despite decades of research into coral biology, we still lack a comprehensive understanding of the attachment process and how to optimize efforts exploiting it. We recently proposed a model explaining the attachment process in Acropora millepora (Lewis BM, Suggett DS, Prentis PJ, Nothdurft LD. 2022 Cellular adaptations leading to coral fragment attachment on artificial substrates in Acropora millepora (Am-CAM). Sci. Rep. 12, 18431. (doi:10.1038/s41598-022-23134-8)). To determine if the model is conserved across coral species, we employed cutting-edge integrated optical and electron microscopy techniques to observe attachment development in two key reef-forming coral genera, including Montipora mollis and Pocillopora verrucosa, comparing them with the previous model, A. millepora. Although developmental steps were broadly conserved, we identified taxonomically distinct variations in immune responses, behaviour, tissue development and skeletal microstructure. These differences explain why certain coral species, like M. mollis and A. millepora, can exhibit faster and stronger attachment compared with P. verrucosa. These findings provide critical diagnostics for asexual success and offer actionable insights into coral fundamental biology and for enhancing reef restoration efforts.