Testing the pressure-specific invertebrate index (PSI) as a tool for determining ecologically relevant targets for reducing sedimentation in streams

摘要: Summary Sedimentation is a major cause of river impairment and water pollution worldwide. However, setting an ecologically meaningful sedimentation target proving challenging due to significant gaps in the understanding quantitative links between ecological response as well variability different types surface waters. This study evaluates utility new pressure-specific macroinvertebrate index, Proportion Sediment-sensitive Invertebrates (PSI), act simple tool for measuring impacts relevant targets. Five indices were calculated from 51 samples taken 13 sampling locations across two neighbouring, but contrasting catchments spring autumn 2010 2011. For four these, environmental quality (EQIs) also proportion observed expected (O:E) scores, which predicted theoretical pristine invertebrate community using River Invertebrate Prediction Classification System model. Principal component analysis has shown clear hydromorphological gradient within catchments. A generalised hierarchical mixed model with site random factor % fine bed sediment fixed found relationship PSI O:E cover at reach-scale resolution over moderate impact. Lotic Index Flow Evaluation (LIFE) scores Ephemeroptera–Plecoptera–Trichoptera (EPT) abundance related cover. was more strongly than either LIFE or EPT abundance. While correlated LIFE, not abundance, suggests differentiated these metrics multiple stressors. The other should be subjected further testing along pronounced stressors, our findings suggest that have potential provide simple, sensitive effective tools ‘twin’ physical targets add additional exploratory power existing suite indices.