Multiple stressors in agricultural streams: interactions among sediment addition, nutrient enrichment and water abstraction

摘要: Summary 1. Many ecosystems are influenced simultaneously by multiple stressors, and the consequences of stressors often unpredictable on basis knowledge single effects. Agriculture affects streams world-wide via nutrient enrichment, elevated fine sediment water abstraction for irrigation, but combined impacts these unknown. 2. We manipulated all three in an 18-day experiment determined their individual pair-wise effects benthic invertebrates, algal biomass leaf decay. We added nutrients (phosphorus plus nitrogen) and/or (grain size 0·2 mm) to 18 experimental stream channels (dimensions 250 × 15 × 15 cm) supplied with from a nearby stream. Three treatments (high, intermediate, natural) were applied each six while flow was reduced 80% half channels. Invertebrates (composition, abundance) algae (chlorophyll a) assayed using ceramic tile substrata decay bundled leaves native shrub. colonizing packs also sampled. 3. Effects addition reduction biological response parameters twice as common enrichment Nutrient increased total invertebrate abundance tiles, accrual rates, whereas both (at highest level) had mostly negative (e.g. biomass, taxonomic richness). 4. Stressors interacted often, interactions between particularly common. The impact aquatic biota stronger at flow, especially that more exposed current than leaf-pack substrata. 5. Synthesis applications. Our key findings imply abstracting already subjected high inputs may have far worse fauna similar lower levels. Aquatic resource managers should be aware this important interaction stressors.