@article{MadgePimentelBaikovaBuchneretal.2024, author = {Madge Pimentel, Iris and Baikova, Daria and Buchner, Dominik and Burfeid Castellanos, Andrea and David, Gwendoline M. and Deep, Aman and Doliwa, Annemie and Hadžiomerović, Una and Mayombo, Ntambwe Albert Serge and Prati, Sebastian and Spyra, Marzena Agata and Vermiert, Anna-Maria and Beißer, Daniela and Dunthorn, Micah and Piggott, Jeremy J. and Sures, Bernd and Tiegs, Scott D. and Leese, Florian and Beermann, Arne J.}, title = {Assessing the response of an urban stream ecosystem to salinization under different flow regimes}, series = {Science of The Total Environment}, volume = {2024 (Special Issue Multilevel response to stressor increase and release in stream ecosystems)}, journal = {Science of The Total Environment}, number = {Volume 926, Artikel Nr. 171849}, publisher = {Elsevier}, doi = {10.1016/j.scitotenv.2024.171849}, pages = {20 Seiten}, year = {2024}, abstract = {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.}, language = {en} }