The majority of Germany’s small agricultural streams are in poor ecological status

Abstract

AbstractAgricultural pesticides, nutrients, and habitat degradation are major causes of insect declines in lowland streams. To effectively conserve and restore stream habitats, standardized stream monitoring data and societal support for freshwater protection are needed. Here, we sampled 137 small stream sites across Germany, 83% of which were located in agricultural catchments, with more than 900 citizen scientists in 96 monitoring groups. Sampling was carried out according to Water Framework Directive standards as part of the citizen science freshwater monitoring program FLOW in spring and summer 2021, 2022 and 2023. The biological indicator SPEARpesticideswas used to assess pesticide exposure and effects based on benthic invertebrate community composition. Overall, 58% of the monitored agricultural stream sites did not achieve a good ecological status in terms of macroinvertebrate community composition and indicated high pesticide exposure (SPEARpesticidesstatus class: 29% ‘moderate’, 19% ‘poor’, 11% ‘bad’). The indicated pesticide pressure in streams was related to the proportion of agricultural land in the catchment area (R2=0.23, p<0.001). With regards to hydromorphology, monitoring results revealed that 65% of the agricultural stream sites failed to reach a good status. The data base produced by citizen science groups was characterized by a high degree of accuracy. This was quantified by a comparative survey of SPEARpesticidesindex (R2=0.79, p<0.001) and hydromorphology index values (R2=0.72, p<0.001) by citizen scientists and professionals. Such citizen-driven monitoring of the status of watercourses could play a crucial role in monitoring and implementing the objective of the European Water Framework Directive, thus contributing to restoring and protecting freshwater ecosystems.Graphical abstractHighlights-Assessment of ecological status of small agricultural streams in Germany-Pesticides affected invertebrates (bioindicator SPEAR) in 58% of agricultural streams-Failure to reach good hydromorphological status in 65% of agricultural streams-Citizen science monitoring achieves high data accuracy-Citizen science can support European Water Framework Directive monitoring