Influence of multiple stressors on watercourses in climate change

Bavarian rivers are among the most important and biodiverse ecosystems in our landscape. However they are also particularly sensitive to climate change. In the interdisciplinary project AquaKlif project partners will investigate climatic stressors such as temperature, precipitation-related fine sediment input and varying runoff and their effects on water ecology and quality. The project will deliver solutions for management of potential climate related stressors to ensure the future health of aquatic ecosystems.

The project focuses on the headwater of upper reaches of river systems and investigates the effects of climatic influences on the hyporheic zone, the highly active reaction space in the transition zone between river and the environment. For this purpose, various typical study sites in the non-Alpine regions of Bavaria have been selected.

The seven subprojects are linked together by cross sectoral themes. In the research phase 2018-2021, the following cross-cutting topics are in focus:

  • Mechanistic understanding of stressors: What exactly happens when different stress factors interact in an “artificial stream” experiment – and can this reaction be theoretically modeled and predicted?
  • Scale effects of stressors: To what extent can the observations from flow channel experiments be observed in the hyporheic zone of real streams – and can the effects of stressors be transfered on entire regions of Bavaria?
  • Analysis of existing data on water quality: Which information can be derived statistically from the long-term monitoring series of water-chemical parameter measurements regarding the influence of climatic stress – and which effects are to be expected for the habitats in streams and rivers on the basis of future climate scenarios?

In the subsequent implementation phase 2021-2023, the focus is on implementation and management as well as environmental education and public outreach. The transition between the research and implementation phases will be accompanied by a central Workshop “Results and recommendations for action” in 2021. To this end, the research results are evaluated with regard to the social, political and administrative implementation of measures, and the objectives of an implementation are defined together with different interest groups. The project AquaKlif is accompanied by a project-related working group.


Stand März 2021

For AquaKlif, the year 2021 marks the transition from research to implementation. Here’s a brief update on the achievements in the AquaKlif subprojects to date, including several photos of different research campaigns.

We would like to thank all the people who have supported us with their experience, drive and ideas,
as well as our financial sponsors and the bayklif head office!

The interdisciplinary flow channel experiment in Freising – center piece for the mechanistic understanding of different stressors – proved to be complex in planning and implementation. Measurements have taken place since summer 2020 with the influence of individual or combined stressors being analyzed over realistic time frames. The aim is to understand the impact of rising temperatures, fine sediment input and lower flow rates on colonization through organisms and fish egg development and how this changes biogeometrical parameters (SP1, SP2 and SP3).  

Since the beginning of the project, data on water ecology and chemistry, stable isotopes and groundwater input has been recorded in numerous measuring campaigns at three selected creeks. The open land results should help to transfer the insights from flow channels to larger scales. The Permuschelbäche in Hof, the Moosach in the calcaerous moraine area, and the Wiesent in Franconian Switzerland represent relevant watercourses in the non-alpine region of Bavaria. It is becoming apparent that the combination of low water levels and high temperatures can drive the precipitation of iron ochre with negative consequences for water ecology (SP1, SP2 and SP3). 

Data recordings over the past 30 years regarding plant societies and water chemistry of more than 100 forest springs in Frankenwald and Fichtelgebirge were continued. Many springs had dried up at the end of the dry summers in 2018 and 2019. Over the years, clear trends have emerged with regards to certain key species and biodiversity (SP4).

Working with regionalized climate scenarios, which were supplied by the State Office of Environment (Landesamt für Umwelt), was particularly exciting. This allowed for a calculation of impact on the level of individual catchment areas. The re-mapping of moor areas around the Lehstenbach showed the advanced degradation of the habitat and enables a more precise modelling and estimation of the actual discharge retention (SP5).

With the help of the Soil and Water Assessment Tool SWAT and the climate scenarios, the potential of agricultural cultivation methods for ecosystem services – in particular erosion regulation, nutrient retention and water supply – is being estimated based on topography, soil and current land use data. The modelling data for the catchment area of Schwesnitz is in full process (SP6).

Early on during the research phase, exciting guests such as Norbert Bäuml (Praxiplattform boden:ständig) and the renown water ecologist Klement Trockner were invited. bayklif research topics were presented at the geoecology annual meeting 2019. Some outreach activities had to be postponed or rearranged due to the pandemic: as such, thematic panel discussions with live stream (“Wasserkonstroversen”) are replacing the workshop for exchanging experiences between science and practice. A podcast on moor renaturation and further digital formats for environmental education are in the making (coordination: SP7).

Currently, measurement and modelling results are being analyzed, publications are in preparation and further data is being recorded in subprojects which started at a later time point. Meanwhile, the AquaKlif team has acquired international reinforcement from South Africa, India and Peru.  

Effects of fine sediment and temperature stress on aquatic communities

Subproject 1

Many stream-dwelling species do not only depend on clean water, but also on a functional stream bed. Fine soil particles that are washed out from surrounding fields and settle on the stream bed can result in colmation and oxygen-depletion. By additional “climate-related stress”, e.g. higher temperatures and extended dry periods with little discharge, but also by torrential rains that cause additional erosion, these effects can be exacerbated.

In this subproject, the scientists investigate at flow channels and real streams the effects of the expected double burden on aquatic animals. They plan to deduce which measures in the restoration of brooks are most promising for future climate conditions.

Principal investigator
Prof. Dr. Jürgen Geist

Chair of Aquatic Systems Biology
Technical University of Munich
Mühlenweg 22
85354 Freising
Tel: +49 8161 713947

Stable Isotopes - Indicators of altered flow conditions and biological turnover in hyporheic zones

Subproject 2

One critical factor for anticipated “good conditions” of waterbodies is the amount of dissolved oxygen. In this subproject, we investigate climate-related shifts of oxygen in streams to characterize ecological states. Based on these results, recommendations for protection of streams will help to establish a more “positive chemistry” in surface waters.

A new measurement method in this subproject will apply stable isotope ratios of dissolved oxygen. It offers new opportunities to determine its pathways in the water column, in sediments and in associated ground waters. These investigations help to answer the following questions:

  • Where does this vital element originate from – photosynthesis or atmosphere?
  • How is oxygen consumed – by bacterial respiration or via precipitation into iron-containing minerals?

Stable isotope investigations can also apply to other elements such as carbon. Such expansions help to better understand interconnections in carbon and oxygen cycles in water compartments including pore- and ground waters. The Applied Geology group of the Friedrich-Alexander-Universität Erlangen-Nürnberg is one of the few laboratories that offers combined isotope measurements of oxygen and carbon in aqueous cycles and thus supplies new tools of investigation in aqueous research.

Principal investigator
Prof. Johannes Barth, Ph. D.
Lehrstuhl für angewandte Geologie
Friedrich-Alexander-Universität Erlangen-Nürnberg
Schlossallee 5
91054 Erlangen
Tel: +49 9131 85 22620

Influence of multiple stressors on N, C and Fe turnover in the hyporheic zone

Subproject 3

Climate change is expected to increase the frequency of periods with little or no rainfall, which will lead to low water levels and flow in streams. Such dry periods have been observed several times in Bavaria during mid and late summer over the last decade. During such draught periods there is an increased risk that certain spots of steam sediment have little or no oxygen, which is both chemically and biologically relevant for stream health. The low oxygen levels induces a whole series of chemical reactions, which are easily recognized by the precipitation of reddish brown iron hydroxides on the steam bed, vegetation and other stream material.

When and where do such oxygen-free zones occur? What is the influence of elevated temperatures, low discharge rates and sediment input on their development? The results of this subproject are important to assess the future water quality of streams and their ecological status.

Principal investigator
Prof. Dr. Stefan Peiffer

Department of Hydrology
University of Bayreuth
Universitätsstraße 30
95447 Bayreuth
Tel: +49 921 55 2251

Principal investigator
Dr. Ben Gilfedder

Department of Hydrology
University of Bayreuth
Universitätsstraße 30
95447 Bayreuth
Tel: +49 921 55 2223

Forest springs as climate indication systems

Subproject 4

For more than 25 years, the Department of Biogeography at the University of Bayreuth has been studying the water of spring areas in Upper Franconian forests as well as the characteristic plant communities growing around these swamp springs. The water chemistry of spring water – as well as certain “indicator” plant species – can be used to deduce ecological processes in the catchment area. The aim of the subproject is to determine if and how the temperature of the springs and the indicator species growing there are related, and how the amount of rain and spring water affects the water temperature. Further spring locations in Steinwald, Oberpfälzer Wald and Bavarian Forest are included to characterize the climatic conditions of Bavarian forest landscapes.

Principal investigator
Prof. Dr. Carl Beierkuhnlein

Chair of Biogeography
University of Bayreuth
Universitätsstraße 30
95447 Bayreuth
Tel: +49 921 552270

Prognosis and analysis of the behavior of small catchment areas in the context of local climate change

Subproject 5

The average temperature of the earth has been rising for a long time now, and the resulting consequences for ecosystems are only poorly understood. It has been shown that climate change also impacts the water chemistry of rivers and streams. 

In this subproject, data of the integrated hydrological monitoring programs collected over decades at the University of Bayreuth and the Bavarian Environment Agency (LfU) are statistically analyzed. Objectives of this subproject are: Are there clear trends and patterns in the time series that can be traced back to local climatic changes in the different catchments? Can causal relationships be proven statistically? Depending on the local climate scenarios of the Bavarian Environment Agency, can it be used to predict future developments of water-chemical parameters?

Principal investigator
Dr. Britta Aufgebauer

Department of Ecological Modelling
University of Bayreuth
Dr.-Hans-Frisch-Straße 1-3
95448 Bayreuth
Tel: +49 921 55 5653

Principal investigator
Dr. Sven Frei

Department of Hydrology
University of Bayreuth
Universitätsstrasse 30
95447 Bayreuth
Tel: +49 921 55 2297

Climate change in Bavaria: water quality and sustainable agriculture

Subproject 6

After heavy rainfall in Bavaria’s streams, the swept-in soil not only clogs the gravelly habitat of many aquatic animals, it also carries along large amounts of nutrients such as nitrogen and phosphorus, which were intended to fertilize meadows and farmland. Instead, these nutrients promote the growth of algae and aquatic plants in the stream – weeding and lack of oxygen at the river bottom are the consequences. 

With climate change, the problem is exacerbated in two ways: on the one hand, the nutrients applied to fields and meadows are more poorly absorbed by the plants in dry phases; on the other hand, more frequent heavy rains are likely to flood the fertilized soil. 

What can be done to keep yields in agriculture as stable as possible in the future and to reduce the nutrient load in waters? In this subproject, climate forecasts for Bavaria are used to investigate how alternative agricultural production measures impact crop yields and nutrient loads in selected river basins.

Principal investigator
Prof. Dr. Thomas Koellner

Professorship of Ecological Services
University of Bayreuth
Universitätsstraße 30
95447 Bayreuth
Tel: +49 921 55 2373

Implementation and outreach activities

Subproject 7

The subproject aims at preparing and implementing the results from the research phase of AQUAKLIF on two levels:

Implementation in practice – deriving options for action

  • through the project-related exchange with a working group of representatives of public authorities, nature conservation and agriculture
  • in a central workshop “Results and recommendations for action” in transition between research and implementation phase
  • with the development of guidelines for the revitalization of streams, conducting of workshops up to the monitoring of pilot projects. 

Implementation within environmental education and public outreach actions

  • by developing new concepts for education on climate protection and aquatic ecology together with the student research laboratories of the University of Bayreuth
  • by further working on the existing student outdoor laboratory “Rotmain-Safari” as a model concept
  • by designing a guideline “Environmental Education: Climate Change and Water Ecology”
  • by communicating results and measures to the public.

Principal investigator
Prof. Dr. Stefan Peiffer

Department of Hydrology
University of Bayreuth
Universitätsstraße 30
95447 Bayreuth
Tel: +49 921 55 2251

Principal investigator
Dr. Birgit Thies

Bayreuth Center of Ecology and Environmental Research
University of Bayreuth
Dr.-Hans-Frisch-Strasse 1-3
95448 Bayreuth
Tel: +49 921 55 5700


  • Sauerstoff als ohnehin knappes Gut in Gewässern könnte noch weniger werden
    Piatka D, Barth JAC
    Klima-Report Bayern 2021: 67
  • Amorphous silica controls water storage capacity and phosphorus mobility in soils
    Schaller J, Frei S, Rohn L, Gilfedder BS
    Frontiers in Environmental Science 2020
  • A first assessment of the impact of the extreme 2018 summer drought on Central European forests
    Schuldt B, Buras A, Arend M (et al., et seq.) Beierkuhnlein, C, Rammig A, Zang CS
    Basic and Applied Ecology 2020; 45: 86-103
  • Quantifizierung lokaler Grundwassereintritte in die Spree und deren Bedeutung für die Verockerungsproblematik in der Lausitz
    Frei S, Wismeth F, Gilfedder BS
    Grundwasser 2020; 25: 231–241
  • Needle in the haystack: tracing groundwater interaction with lakes and streams across temporal and spatial scales using radon
    Gilfedder B, Kaule R
    Forum Geoökologie 2020; 1/2020: 13-15
  • Predicted climate shifts within terrestrial protected areas worldwide
    Hoffmann S, Irl SDH, Beierkuhnlein C
    Nature Communications 2019; 10: 4787
  • Fließgewässer im Klimastress: Diagnose und Prognose mittels innovativer Methoden
    Peiffer S, Thies B
    Umwelttechnologie und Energie in Bayern 2019: 44-46; München, media mind

Doctoral Thesis

  • Influence of multiple stressors on N, C and Fe turnover in the hyporheic zone
    Kaule, Robin (derzeit PhD bei Dr. Gilfedder, AquaKlif TP3)
  • Prognosis and analysis of the behavior of small catchment areas in the context of local climate change
    Kaule, Lisa (derzeit PhD bei PD Dr. Frei, AquaKlif TP5)
  • Homogenisation of forest spring ecosystems
    Smith, Timothy J. (derzeit PhD bei Prof. Beierkuhnlein, AquaKlif TP4)
  • Oxygen and carbon dynamics in freshwater systems as a proxy for future developments due to climate change and land use
    Piatka, David (derzeit PhD bei Prof. Barth, AquaKlif TP2)

Final Papers

  • Drivers of dissolved oxygen dynamics in streams and hyporheic zones inferred from natural and controlled systems
    Daxeder, Luisa (Masterarbeit 2020 bei Prof. Barth, AquaKlif TP2 )
  • Prediction of stream water and hyporheic temperature in the context of local climate change: a case study at the Bavarian Mähringsbach, Fichtel Mountains
    Drainas, Konstantina (Masterarbeit 2020 bei Prof. Geist / Romy Wild, AquaKlif TP1, mitbetreut von Lisa Kaule, TP5)
  • A short oxygen isotope analysis and hydrogeological overview of Bavarian streams accompanied by sampling validation experiments
    Bittman, Lennart (Masterarbeit 2020 bei Prof. Barth, AquaKliF TP2 )
  • Die Auswirkungen multipler anthropogener und klimabedingter Stressoren auf die Laubabbauraten und die Artenzusammensetzung der laubabbauenden Makroinvertebraten in ausgewählten Fließgewässern Bayerns
    Kreidenweis, Markus (Masterarbeit 2020 bei Prof. Geist, AquaKlif TP1 )
  • Die Auswirkungen multipler anthropogener Stressoren auf Laubabbauraten in Fließgewässern unter Anwendung des Tea-bag Index
    Schmitt, Phillip (Bachelorarbeit 2020 bei Prof. Geist, AquaKlif TP1 )
  • Hydrochemische und stabile Isotopenuntersuchungen von Freiwasser und Sedimentwasser in Bayerischen, nicht-alpinen Fließgewässern im Rahmen des AquaKlif Projektes
    Paulus, Fabian (Masterarbeit 2019 bei Prof. Barth, AquaKlif TP2 )