TY - JOUR A1 - Madge Pimentel, Iris A1 - Baikova, Daria A1 - Buchner, Dominik A1 - Burfeid Castellanos, Andrea A1 - David, Gwendoline M. A1 - Deep, Aman A1 - Doliwa, Annemie A1 - Hadžiomerović, Una A1 - Mayombo, Ntambwe Albert Serge A1 - Prati, Sebastian A1 - Spyra, Marzena Agata A1 - Vermiert, Anna-Maria A1 - Beißer, Daniela A1 - Dunthorn, Micah A1 - Piggott, Jeremy J. A1 - Sures, Bernd A1 - Tiegs, Scott D. A1 - Leese, Florian A1 - Beermann, Arne J. T1 - Assessing the response of an urban stream ecosystem to salinization under different flow regimes JF - Science of The Total Environment N2 - Abstract Urban streams are exposed to a variety of anthropogenic stressors. Freshwater salinization is a key stressor in these ecosystems that is predicted to be further exacerbated by climate change, which causes simultaneous changes in flow parameters, potentially resulting in non-additive effects on aquatic ecosystems. However, the effects of salinization and flow velocity on urban streams are still poorly understood as multiple-stressor experiments are often conducted at pristine rather than urban sites. Therefore, we conducted a mesocosm experiment at the Boye River, a recently restored stream located in a highly urbanized area in Western Germany, and applied recurrent pulses of salinity along a gradient (NaCl, 9 h daily of +0 to +2.5 mS/cm) in combination with normal and reduced current velocities (20 cm/s vs. 10 cm/s). Using a comprehensive assessment across multiple organism groups (macroinvertebrates, eukaryotic algae, fungi, parasites) and ecosystem functions (primary production, organic-matter decomposition), we show that flow velocity reduction has a pervasive impact, causing community shifts for almost all assessed organism groups (except fungi) and inhibiting organic-matter decomposition. Salinization affected only dynamic components of community assembly by enhancing invertebrate emigration via drift and reducing fungal reproduction. We caution that the comparatively small impact of salt in our study can be due to legacy effects from past salt pollution by coal mining activities >30 years ago. Nevertheless, our results suggest that urban stream management should prioritize the continuity of a minimum discharge to maintain ecosystem integrity. Our study exemplifies a holistic approach for the assessment of multiple-stressor impacts on streams, which is needed to inform the establishment of a salinity threshold above which mitigation actions must be taken. KW - Macroinvertebrates KW - Algae KW - Fungi KW - Parasites KW - Organic-matter decomposition KW - Primary production Y1 - 2024 UR - https://www.sciencedirect.com/science/article/pii/S0048969724019922 U6 - https://doi.org/10.1016/j.scitotenv.2024.171849 VL - 2024 (Special Issue Multilevel response to stressor increase and release in stream ecosystems) IS - Volume 926, Artikel Nr. 171849 PB - Elsevier ER -