Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Do pools impede drift dispersal by stream insects? Freshwater Biology 62: 1578–1586.īunn, S. Parallels and contrasts in the effects of drought on stream macroinvertebrate assemblages. Archives of Environmental Contamination & Toxicology 55: 247–253.īoulton, A. Potential of 11 pesticides to initiate downstream drift of stream macroinvertebrates. River Research and Applications 27: 388–401.īeketov, M. ![]() Downstream effects of diversion dams on sediment and hydraulic conditions of Rocky Mountain streams. Water abstraction impacts stream ecosystem functioning via wetted-channel contraction. Stream Ecology: Structure and Function of Running Waters. Therefore, our results suggest that water abstraction influences drift, with potentially important consequences for the invertebrate assemblages and ecosystem processes further downstream.Īlcamo, J. While drift rates remained unchanged after water abstraction, the Impact reach became a net invertebrate exporter indicating that many taxa drifted actively as a response to stressful conditions rather than passively, which would be reduced by water abstraction. By contrast, drift densities of other abundant taxa, such as Baetis, Esolus and chironomids, increased less than what could be expected from the magnitude of flow reduction. ![]() The sudden decrease in flow promoted a 12-fold increase in overall drift density at the Impact reach, which was primarily driven by filterers, shredders and taxa associated with fast velocities, such as simulids. We also identified the specific taxa and traits that drove these responses. We measured flow-reduction effects on drift densities (animals/m 3), total drift rates (animals leaving the reach per hour) and net balance of invertebrates entering or leaving the Impact reach. We examined this issue with a before–after–control–impact design experiment in which we diverted 90% of the natural flow from a headwater stream. Water abstraction modifies the environmental conditions of stream ecosystems, which can affect invertebrate assemblages by altering drift.
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