The impact of predation on the structuring of Arctic intertidal soft-bottom communities

Predation is a key modifier of community dynamics, but information on its magnitude in community regulation in systematically understudied Arctic coastal habitats is sparse. To test the magnitude and direction of predation effects on the diversity and structure of Arctic benthic communities, we conducted caging experiments in which consumers were excluded from plots at two intertidal sedimentary sites in Svalbard (Longyearbyen and Thiisbukta) for 2.5 months. At the end of the experiment, we took a sediment core from each plot and quantified the total biomass and, separately for each taxon encountered, the number of individuals. At both sites, the exclusion of predators changed the species composition of the communities, but had negligible effects on biomass, total abundance, species richness, evenness and Shannon index. In addition, we found spatial variability and artifact effects at both sites on several response variables.