Data from: Piscivore addition causes a trophic cascade within and across ecosystem boundaries

AbstractThe addition of predators can play a key role in structuring ecological communities through both consumptive and non-consumptive effects. Stocking of piscivorous fish in lakes and similar experimental introductions have provided fundamental evidence in support of trophic cascade theory. Yet, the impact of piscivore addition on cross ecosystem subsidies and meso-predator resource use has not been well studied. Here, we use a replicated pond experiment to document the trophic impacts of a piscivore, cutthroat trout Onchorhynchus clarkii, on aquatic communities already containing a meso-predatory fish (threespine stickleback Gasterosteus aculeatus) and neighbouring terrestrial ecosystems. We find that piscivore addition led to a trophic cascade that extended across an ecosystem boundary: trout addition increased the biomass and average size of insects emerging into the terrestrial system. Piscivores caused a diet shift in stickleback, a non-consumptive effect that was likely mainly responsible for the increase in emerging insect biomass. We additionally show that heterogeneity in the strength of the pelagic trophic cascade was more closely correlated with the magnitude of diet shift (reflecting a non-consumptive effect) than decreases in stickleback abundance (a consumptive effect). Taken together, our experiment demonstrates that the addition of a piscivore causes a trophic cascade that can extend beyond the aquatic system and suggests that non-consumptive effects may more strongly influence the strength of a trophic cascade than has been previously recognized., Usage notesPiscivore_addition_zooplanktonData_160323Zooplankton data collecting for the study as described in Rudman et al. 2016.Piscivore_addition_phytoplanktonData_160323Phytoplankton data used collected from experiment described by Rudman et al. 2016.Piscivore_addition_EmergingInsects_160323Emerging insect data from Rudman et al. 2016.Piscivore_addition_CascadeCorrelates_160323Data file with calculated strength of trophic cascade, measure of consumptive, and non-consumptive effects from Rudman et al. 2016.Piscivore_addition_sticklebackDiet_160323Stickleback diet data from Rudman et al. 2016.