Predicting shifts in demography of Orbicella franksi following simulated disturbance and restoration

Disturbances of coral reefs are increasing in frequency, intensity, and duration. These changes will likely result in demographic shifts in many populations of reef-building corals with unknown consequences for ongoing coral restoration efforts. To address this knowledge gap, here we use empirically derived stage-based matrix population models to predict how a relatively stable population and areal coverage of Orbicella franksi may change under simulated disturbance and restoration scenarios. Overall, simulated restoration outplanting greatly increased the number of O. franksi colonies and overall estimated areal coverage when compared to baseline population estimates. Under a mild disturbance scenario, the number of O. franksi colonies were projected to decrease by up to 90% by 2050, but simulated restoration was predicted to offset the loss in number of colonies. Under a severe disturbance scenario, the number of O. franksi colonies also decreased, but simulated restoration efforts were not able to offset colony losses. Under both disturbance scenarios there was a large projected loss of O. franksi areal coverage even when restoration was implemented. However, restoration prevented a rapid decrease in number of colonies in the severe disturbance scenario. These findings highlight the potentially catastrophic effects of disturbances on previously stable coral populations, and the role restoration can play in mitigating these threats. Increasing studies focused on widespread ecological and demographic monitoring of disturbed and restored corals will be critical in the development of more effective restoration strategies for conserving these threatened species in an uncertain future.