Direct and indirect effects of nursery habitats on coral-reef fish assemblages, grazing pressure, and benthic dynamics

Migrating species are common within seascapes, but the potential for these movements to alter the populations and functional roles of non-migrating species (e.g. by increasing predation) is rarely investigated. This study considers whether the presence of nursery habitats (mangroves and seagrass) simply enhances the abundance of nursery-using parrotfishes and piscivores on nearby coral reefs, or also affects other parrotfishes. Data from 131 reef sites and multiple seascape configurations across 13 degrees of latitude were used to model correlations between biophysical variables, including nursery habitat connectivity, and the abundance and grazing pressure of both nursery-using species and other parrotfishes and piscivore biomass. Connectivity to mangroves and dense seagrass was positively correlated with the biomass of nursery-using species, but was also negatively correlated with non-nursery parrotfish populations. This reduction may be caused indirectly by nursery habitats increasin...