Interactions between pH and nutrients on benthic algae in streams and consequences for ecological status assessment and species richness patterns

► Acid-tolerant taxa are usually also associated with nutrient-poor conditions. ► This could lead to a drift in nutrient indices with recovery from acidification. ► pH-gradients interfere with nutrient indices and patterns in taxon richness. ► Diatom taxon richness increases with nutrients, while non-diatoms decrease.