Identifying attributes of coral reef ecosystems that confer resilience to disturbances is a pressing challenge, and necessary for devising successful management strategies. Functional traits are likely to moderate the links between disturbances and ecological resilience of coral reefs, but our understanding of these interrelations remains severely limited. By facilitating simultaneous manipulation of many variables, agent-based models (ABMs) offer a powerful approach to filling this knowledge gap, provided they are sufficiently well founded in process and mechanism, and are adequately parameterized. We constructed such an ABM of a coral community in order to better understand the interrelations between functional trait composition, diversity, and resilience. Within our ABM, a set of functional traits, derived from published data, moderates an agent’s behaviour. We conducted a factorial simulation experiment in which functional diversity (FD, the volume of trait space occupied by a community), functional composition (FC, the location/centroid in trait space), the intensity and the frequency of cyclone disturbance were manipulated. We measured the community’s resilience via (i) resistance (i.e., percentage cover surviving the disturbance), (ii) recovery (i.e., time necessary to return to the pre-disturbance percentage cover) and (iii) capacity to maintain its functional identity (i.e., proportion of functional volume preserved and recovered).
Results/Conclusions
We found that FC strongly influenced resilience, regardless of the FD of the initial community. In particular, the presence of highly competitive species decreased the resistance and increased the recovery of the community. Large colonies with complex morphologies (i.e., branching or plating) and rapid growth rates are the main traits characteristics responsible for the high competitiveness, fragility and fast recovery of these dominant species. These results are specific to cyclones and future work will examine the relationship with other types of disturbances (e.g., bleaching events). Thus, by conferring insights about the species that best functionally complement an existing community, our approach can inform management measures such as restoration to help build more resilient reef communities.