The role of dispersal and demography in determining the efficacy of marine reserves

Marine reserves are rapidly becoming an important tool for protection and recovery of depleted marine populations. However, the relative value of reserves to particular species is strongly dependent on its life history and behavior. We present a general conceptual framework for considering dispersal in simple demographic models. This framework includes transition matrices that consist of two age-structured models connected by transition probabilities for general migration, ontogenetic shifts, and recruitment in both a reserve and an unprotected area. We show that life history characteristics and perturbation analysis can be used to predict changes in growth rate due to a decrease in adult mortality resulting from a marine reserve for different levels and types of dispersal. Reserves enhanced growth rate for all species irrespective of net dispersal between the reserve and surrounding matrix habitat, but the efficacy of reserves relative to catch reduction depended significantly on the magnitude and sign of net dispersal across the reserve boundary. Patterns of reserve efficacy across different dispersal types were strongly species specific. Given the paucity of spatially explicit data for many marine systems and species, this simple approach represents a first step in applying life history information to advance current theory and provide practical considerations for marine reserve management.