How dispersal and habitat quality shape aquatic–terrestrial metacommunities

Abstract

Current changes in land use, predominantly from agriculture and urbanization, affect both habitat quality and species dispersal ability. Understanding how these factors influence species distributions in aquatic–terrestrial metacommunities is critical for predicting community dynamics. In this study, we developed a spatially explicit metacommunity model that integrates generated landscapes with a simple four-species, two-trophic-level community consisting of an aquatic emerging prey, a terrestrial prey, and two predators with different prey preferences (aquatic vs. terrestrial). Habitat quality of local stream habitats was determined by upstream agricultural land use, while predator dispersal matrices were generated from simulated movement across heterogeneous landscapes. This framework allowed us to disentangle the relative and interacting roles of habitat quality and dispersal in shaping species abundances. Our simulations revealed that the relative importance of habitat quality and dispersal differed across species. By design, habitat quality only influenced the aquatic prey directly, and dispersal was possible only for predators. However, through ecological dynamics within the food web, habitat quality and dispersal also influenced the other species. Habitat quality had the strongest positive effect on the predator with aquatic preference, mediated through increases in aquatic prey. This, in turn, resulted in a decline in terrestrial prey, whereas the predator with terrestrial preference was largely unaffected. The effects of dispersal on the predator with aquatic preference were generally stronger than the effects of habitat quality, but exhibited a stronger variability, driven by landscape and community parameters. The dynamics of the predator with terrestrial preference were dominated by dispersal effects, whereas those of aquatic prey were shaped by habitat quality, and the terrestrial prey responded approximately equally to both processes. This study provides a framework for understanding how spatial processes interact with local habitat factors to shape ecological communities in fragmented landscapes. Our findings emphasize that dispersal dynamics need stronger consideration in empirical field studies, as context-specific dispersal mechanisms can strongly affect community composition.