title: The biogeography of trophic cascades on US oyster reefs.
abstract: Predators can indirectly benefit prey populations by suppressing mid-trophic level consumers, but often the strength and outcome of trophic cascades are uncertain. We manipulated oyster reef communities to test the generality of potential causal factors across a 1000-km region. Densities of oyster consumers were weakly influenced by predators at all sites. In contrast, consumer foraging behaviour in the presence of predators varied considerably, and these behavioural effects altered the trophic cascade across space. Variability in the behavioural cascade was linked to regional gradients in oyster recruitment to and sediment accumulation on reefs. Specifically, asynchronous gradients in these factors influenced whether the benefits of suppressed consumer foraging on oyster recruits exceeded costs of sediment accumulation resulting from decreased consumer activity. Thus, although predation on consumers remains consistent, predator influences on behaviour do not; rather, they interact with environmental gradients to cause biogeographic variability in the net strength of trophic cascades.
authors.affiliation: Marine Science Center, Department of Marine and Environmental Sciences, Northeastern University, 430 Nahant Road, Nahant, MA, 01908, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Kimbro
authors.forename: James E
authors.initials: JE
authors.lastname: Byers
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Grabowski
authors.forename: A Randall
authors.initials: AR
authors.lastname: Hughes
authors.forename: Michael F
authors.initials: MF
authors.lastname: Piehler
mesh_terms: D000818:Animals; D020387:Food Chain; D010125:Ostreidae / Q000502:physiology*; D058974:Phylogeography; D011157:Population Dynamics; D015144:Southeastern United States
keywords: Behaviour; consumptive effect; density-mediated indirect interaction; environmental gradient; foundation species; non-consumptive effect; predation; recruitment; trait-mediated indirect interaction