Disentangling multiple chemical and non-chemical stressors in a lotic ecosystem using a longitudinal approach

Markus Weitere, Rolf Altenburger, Christine Anlanger, Martina Baborowski, Ilona Bärlund, Liza Marie Beckers, Dietrich Borchardt, Werner Brack, Lisa Brase, Wibke Busch, Antonis Chatzinotas, Björn Deutschmann, Jens Eligehausen, Karin Frank, Daniel Graeber, Christian Griebler, Jeske Hagemann, Peter Herzsprung, Henner Hollert, Pedro A. InostrozaChristoph G. Jäger, René Kallies, Norbert Kamjunke, Bernhard Karrasch, Sigrid Kaschuba, Andrew Kaus, Bernd Klauer, Kay Knöller, Matthias Koschorreck, Martin Krauss, Julia V. Kunz, Marie J. Kurz, Matthias Liess, Margarete Mages, Christin Müller, Matthias Muschket, Andreas Musolff, Helge Norf, Florian Pöhlein, Lena Reiber, Ute Risse-Buhl, Karl Werner Schramm, Mechthild Schmitt-Jansen, Markus Schmitz, Ulrike Strachauer, Wolf von Tümpling, Nina Weber, Romy Wild, Christine Wolf, Mario Brauns

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

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.

Original languageEnglish
Article number144324
JournalScience of the Total Environment
Volume769
DOIs
StatePublished - May 15 2021
Externally publishedYes

Funding

This integrated research activity received program-oriented funding under the research area Earth and Environment of the Helmholtz Association (Germany) from 2014 until 2020. The icons for the graphical abstract were created by Susan Walter-Pantzer (Helmholtz Centre for Environmental Research - UFZ).

FundersFunder number
Helmholtz Association

    Keywords

    • Ecological functions
    • Effect based analyses
    • Indicators
    • Multiple stress
    • Running waters

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