Interactions between disturbance and dispersal reduce persistence thresholds in a benthic community

Interactions between the scale of dispersal and the disturbance regime can lead to radical shifts in the ability of organisms to colonize patches and persist within a landscape. We varied the spatial and temporal rates of disturbance and the connectivity between patches in a model of a patch landscape to illustrate thresholds of community persistence for a marine benthic community. We used model parameters representative of a New Zealand marine biogenic-structured community for which recovery after the cessation of disturbance has been observed within similar to 15 yr. Model results suggest functional extinction of these biogenic communities under many disturbance regimes, and homogenization of the landscape to a community dominated by opportunistic species. Dispersal limitation increases in importance for recovery as the disturbance regime strengthens, indicating thresholds in the tolerable disturbance regime based on the dispersal potential of the dominant biogenic species. Limited sensitivity of our model results to different functional forms of the recovery trajectory and colonization neighborhood suggest that these results can be extrapolated to other biogenic structure-dominated communities with recovery rates of a similar order of magnitude. Our results demonstrate that the scale of the disturbance regime and dispersal processes are fundamentally coupled, and knowing the scales of both processes is imperative when predicting change in the structure and diversity of benthic communities threatened by cumulative change.