Extreme climatic events alter the aquatic insect community in a pristine German stream

Abstract As a result of ongoing climate change, extreme climatic events (ECEs) are expected to become more frequent and severe. The high biodiversity riverine ecosystems is susceptible ECEs, especially water temperature (extreme heat cold) discharge-related (flood drought) events. Long time series needed unravel the effects ECEs on ecological communities. Here, we used 20 years (1986–2005) unusually high-resolution data from pristine first-order stream in Germany. Daily recordings species-level identified aquatic insect (Ephemeroptera, Plecoptera, Trichoptera: EPT) emergence, discharge were examine four types heat, cold, flood, drought events) abundance, common taxonomic diversity metrics, selected traits after five different lags (2 weeks, 1, 3, 6, 12 months). Extreme increased 1.8 ± 1.9 SE per year before 2000 5.3 2000. Water temperature-related restructured EPT community species richness, (community index: CTI, dispersal capacity metric: DCM). strongest found when it was exposed multiple 1 3 months an ECE. changing frequencies durations increasing frequency negative cumulative paint worrisome picture for future communities headwater streams. High-resolution, long-term across sites further disentangle ECE stressors.