title: Species invasion shifts the importance of predator dependence.
abstract: The strength of interference between foraging individuals can influence per capita consumption rates, with important consequences for predator and prey populations and system stability. Here we demonstrate how the replacement of a previously established invader, the predatory crab Carcinus maenas, by the recently invading predatory crab Hemigrapsus sanguineus shifts predation from a species that experiences strong predator interference (strong predator dependence) to one that experiences weak predator interference (weak predator dependence). We demonstrate using field experiments that differences in the strength of predator dependence persist for these species both when they forage on a single focal prey species only (the mussel Mytilus edulis) and when they forage more broadly across the entire prey community. This shift in predator dependence with species replacement may be altering the biomass across trophic levels, consistent with theoretical predictions, as we show that H. sanguineus populations are much larger than C. maenas populations throughout their invaded ranges. Our study highlights that predator dependence may differ among predator species and demonstrates that different predatory impacts of two conspicuous invasive predators may be explained at least in part by different strengths of predator dependence.
authors.affiliation: Odum School of Ecology, University of Georgia, Athens, Georgia 30602-2202, USA. bgriffen@uga.edu
authors.forename: Blaine D
authors.initials: BD
authors.lastname: Griffen
authors.forename: David G
authors.initials: DG
authors.lastname: Delaney
mesh_terms: D000818:Animals; D018533:Biomass; D049872:Bivalvia / Q000502:physiology*; D003386:Brachyura / Q000502:physiology*; D017753:Ecosystem; D020387:Food Chain; D011156:Population Density; D011157:Population Dynamics; D011158:Population Growth; D011235:Predatory Behavior / Q000502:physiology*; D013045:Species Specificity