Together with Romana Salis, Katie Blakemore and Christoph Matthaei from the University of Otago (New Zealand) and Ralph Tollrian from the Ruhr University Bochum, Jan Macher and Florian Leese investigated the impact of multiple anthropogenic stressors on morphological cryptic species of the New Zealand mayfly genus Deleatidium.The genus Deleatidium is an important indicator taxon in New Zealand, commonly thought to indicate good water quality. In their newly published paper in the Journal Ecological Indicators with the title “Multiple-stressor effects on stream invertebrates: DNA barcoding reveals contrasting responses of cryptic mayfly species”, Jan and Florian could show that Deleatidium species show contrasting responses to agricultural stressors. While stressors have strong negative effects on some species, other species show no reaction to stressors at all. This has consequences for future water quality assessments as not all species are versatile indicators of poor water quality. The data show that more information on the ecology of freshwater taxa is urgently needed.