@article{WeitereAltenburgerAnlangeretal.2021, author = {Weitere, Markus and Altenburger, Rolf and Anlanger, Christine and Baborowski, Martina and B{\"a}rlund, Ilona and Beckers, Liza-Marie and Borchardt, Dietrich and Brack, Werner and Brase, Lisa and Busch, Wibke and Chatzinotas, Antonis and Deutschmann, Bj{\"o}rn and Eligehausen, Jens and Frank, Karin and Graeber, Daniel and Griebler, Christian and Hagemann, Jeske and Herzsprung, Peter and Hollert, Henner and Inostroza, Pedro A. and J{\"a}ger, Christoph G. and Kallies, Ren{\´e} and Kamjunke, Norbert and Karrasch, Bernhard and Kaschuba, Sigrid and Kaus, Andrew and Klauer, Bernd and Kn{\"o}ller, Kay and Koschorreck, Matthias and Krauss, Martin and Kunz, Julia V. and Kurz, Marie J. and Liess, Matthias and Mages, Margarete and M{\"u}ller, Christin and Muschket, Matthias and Musolff, Andreas and Norf, Helge and P{\"o}hlein, Florian and Reiber, Lena and Risse-Buhl, Ute and Schramm, Karl-Werner and Schmitt-Jansen, Mechthild and Schmitz, Markus and Strachauer, Ulrike and von T{\"u}mpling, Wolf and Weber, Nina and Wild, Romy and Wolf, Christine and Brauns, Mario}, title = {Disentangling multiple chemical and non-chemical stressors in a lotic ecosystem using a longitudinal approach}, series = {Science of the Total Environment}, volume = {769}, journal = {Science of the Total Environment}, pages = {144324}, year = {2021}, abstract = {Meeting ecological and water quality standards in lotic ecosystems is often failed due to multiple stressors. However, disentangling stressor effects and identifying relevant stressor-effect-relationships in complex environmental settings remain major challenges. By combining state-of-the-art methods from ecotoxicology and aquatic ecosystem analysis, we aimed here to disentangle the effects of multiple chemical and non-chemical stressors along a longitudinal land use gradient in a third-order river in Germany. We distinguished and evaluated four dominant stressor categories along this gradient: (1) Hydromorphological alterations: Flow diversity and substrate diversity correlated with the EU-Water Framework Directive based indicators for the quality element macroinvertebrates, which deteriorated at the transition from near-natural reference sites to urban sites. (2) Elevated nutrient levels and eutrophication: Low to moderate nutrient concentrations together with complete canopy cover at the reference sites correlated with low densities of benthic algae (biofilms). We found no more systematic relation of algal density with nutrient concentrations at the downstream sites, suggesting that limiting concentrations are exceeded already at moderate nutrient concentrations and reduced shading by riparian vegetation. (3) Elevated organic matter levels: Wastewater treatment plants (WWTP) and stormwater drainage systems were the primary sources of bioavailable dissolved organic carbon. Consequently, planktonic bacterial production and especially extracellular enzyme activity increased downstream of those effluents showing local peaks. (4) Micropollutants and toxicity-related stress: WWTPs were the predominant source of toxic stress, resulting in a rapid increase of the toxicity for invertebrates and algae with only one order of magnitude below the acute toxic levels. This toxicity correlates negatively with the contribution of invertebrate species being sensitive towards pesticides (SPEARpesticides index), probably contributing to the loss of biodiversity recorded in response to WWTP effluents. Our longitudinal approach highlights the potential of coordinated community efforts in supplementing established monitoring methods to tackle the complex phenomenon of multiple stress.}, language = {en} }