Coral community demographics: the variation between tropical and subtropical assemblages

Climate change is exposing coral reefs worldwide to increasingly recurrent disturbances. However, with current knowledge of coral population dynamics focused on long-term (i.e., asymptotic) characteristics, our capacity to forecast the resilience of coral communities, specifically, their resistance and recovery following disturbances, is restricted. Recurrent disturbances ensure that populations never achieve a stable equilibrium and will thus never attain their asymptotic trajectories. Instead, it is imperative that we quantify the performance of coral populations within non-stationary environments using their transient (i.e., short-term) dynamics, and evaluate the determinants of variation across these transient dynamics as conditions change. Here, I utilise state-structured demographic approaches and transient demographic theory to explore the association between abiotic variation and measures of demographic resilience. I illustrate how patterns in demographic resilience across animal and plant populations do not correlate with gradients in their exposure to abiotic variability, and thus recent experience of variable environments does not guarantee resilience to future climate variability. Next, I explore these insights in the context of resistance and recovery in coral populations to enhance understanding of coral community resilience. Using an Integral Projection Model framework, I show how, despite enduring more variable seasonal climates, subtropical coral communities remain vulnerable to future recurrent thermal stress. I also demonstrate how spatial variation in the transient dynamics of acroporid coral populations in southern Japan underpins the establishment of populations at higher latitudes. Finally, to further explore the mechanisms facilitating the establishment of subtropical coral populations, I evaluate spatial patterns in the impact of environmental variability on the long-term performance and transient dynamics of coral populations across coral taxa. Overall, this research represents a crucial step in quantifying the transient dynamics of coral populations, an approach which requires greater commitment if we are to anticipate the future resilience, viability, and condition of global coral communities.