Reactive persistence of riverine metapopulations

Abstract

Understanding the conditions that favor the persistence of metapopulations inhabiting riverine landscapes (riverscapes) is critical to guiding conservation and restoration efforts aimed at preserving biodiversity and ecological integrity in freshwater environments. In this study, we present a modeling framework to examine the transient persistence of fluvial metapopulations---the temporary occupation of riverscape patches by a metapopulation expected to become extinct in the long run. Our approach is theoretically grounded in the concept of ecological reactivity, which effectively complements asymptotic stability analysis in the study of the short-term response of ecological systems to impulsive perturbations of otherwise stable steady states. Our results suggest that, under ecohydrological conditions conducive to reactive metapopulation extinction equilibria, a metapopulation asymptotically bound to extinction can still colonize parts of the riverscape for significant periods of time. We also find that, in the presence of repeated positive perturbations of the extinction equilibrium, the temporal scales associated with these transient phenomena may allow for reactive pseudo-persistence. This phenomenon involves an arbitrarily long delay in the eventual extinction of the metapopulation, which may occur well below the deterministic extinction threshold. Identifying the ecohydrological drivers of reactivity-driven metapopulation persistence and the riverscape patches that contribute most to transient metapopulation dynamics over different temporal scales may provide valuable suggestions for the spatial prioritization of conservation and restoration efforts.