Origins of functional connectivity in a human-modified wetland landscape

Abstract

Spatial heterogeneity in habitat conditions within a landscape should influence degree of movement of species between natural and artificial environments. For wetland landscapes, this functional connectivity was predicted to emerge from the influence of spatiotemporal patterns of depth on permeability of habitat edges and distance and directedness of cross-habitat dispersal. We quantified how connectivity between canals and marshes of the Florida Everglades varies with species and landscape patterns bordering canals by using radio telemetry to measure movement of a native (Florida largemouth bass, Micropterus salmoides floridanus) and a nonnative species (Mayan cichlid, Cichlasoma urophthalmus) common to canals. Both species moved similar distances inside canal networks, but Mayan cichlids dispersed outside of canals more frequently, at shallower conditions, and over greater distances than Florida largemouth bass. As topographic relief increased in marshes bordering canals, dispersal between these habitats decreased in distance and became more directed, with Florida largemouth bass sensitive to depth variability at a smaller spatial scale than Mayan cichlids. The way fish traits interact with submerged landscape structure to influence connectivity can serve as a basis for predicting potential impacts of artificial habitats that arise from dispersal outside their borders.