The effect of hydrological disturbance on the impact of a benthic invertebrate predator

Abstract

The harsh-benign model of community dynamics predicts that the impact of predation will decline as abiotic conditions become more stressful to biota. Experiments were conducted to determine whether hydrological disturbance altered the impact of an invertebrate predator in stream benthic communities. The impact of a predatory stonefly, Cosmioperla kuna, on its mayfly prey was measured in experimental stream channels receiving constant or variable flow (flooding) regimes over a one-week period. Contrary to predictions of the harsh-benign hypothesis, the impact of Cosmioperla on its two major prey taxa was either unchanged or increased by artificial floods, despite increased predator emigration..