Sub-project 1: Determination and quantification of flow traits of benthic invertebrates in river ecosystems

Expected alterations in community structure of aquatic invertebtrates under global change can be estimated only if hydrological/hydraulic preferences and tolerances of target species get assessed numerically
Sub-project 1 details

Hydrological and hydraulic conditions are key habitat variables in running waters. It is anticipated that global change may induce flow alterations in space and over time. Such changes in stream flow will have consequences for the biological communities of aquatic invertebrates – particularly, it may affect their diversity, composition and distribution. Flow changes can be described in great detail by numerous observed and simulated hydrological flow indices providing information on magnitude, timing, rate, duration and frequency of changes in hydrological conditions. In contrast, surprisingly little empirical based knowledge on the ecological requirements (aka traits) of benthic invertebrates is available: e.g. preferences are described on nominal scale (such as habitat preference) or ordinal scale (current preferences) and have often been assessed based on literature analysis and/or expert knowledge. Being descriptive, these ecological traits are of limited value to quantify effects of changes in flow. The aim of the study was thus to determine and quantify preferences of invertebrates regarding flow conditions (“hydrological traits”) to describe the species response to flow changes in greater detail. 

The study is conducted throughout Germany by analyzing existing data available from environmental agencies. Two datasets are collected: (1) long-term hydrological data recorded at all available gauging stations throughout the country and results from benthic invertebrate samples of Germany's rivers and streams. (2) Sampling in three model catchments in Germany, namely a lowland (Treene), a mountainous (Kinzig) and an alpine catchment (Ammer, a TERENO observatory site).

From the hydrological data we calculate hydrological indices i.e. discharge/flow values, including mean or long‐term hydrological conditions, min./max. values, ranges, or seasonal metrics. We then identify preferences for different hydrological conditions with different statistical methods. The results of this study improves our understanding of stream-specific effects of global change, and may be beneficial e.g. for management planning.

Contact for sub-project 1
Karan Kakouei,
Tel.: +49 (0)30 6392 4098, Website

Sub-project 2: Quantification of global change impacts on hydrological and hydraulic conditions

A simulation model will depict the recent past and current conditions regarding hydrological and hydraulic parameters, followed by a prediction model showing explicit data on flow conditions under climate change
Sub-project 2 details

This subproject deals with the simulation of hydrologic and hydraulic parameters in three German catchments in different ecoregions: The Treene in the northern lowlands, the Kinzig in the low mountain range and the Ammer in the alpine region. In each catchment, a hydrologic, 1D and 2D hydraulic model cascade is applied. Through this, hydrologic and hydraulic parameters, which are relevant for benthic invertebrates, are depicted for the recent past and for the next decades. Necessary input data ranges from catchment properties like soils, landuse and management to climate as well as river structure and stream geometry. To gather this data, existing data sources are screened, measurement campaigns are carried out and climate projections are incorporated.
At first, a simulation of the recent past and current state is carried out. As soon as those are satisfactory, the models are used to assess the impact of expected global changes on alterations of hydrologic and hydraulic conditions. Model output includes temporally and spatially explicit data on different scales, i.e. river discharge, flow velocities and water depth. These simulated in-stream data are an important information to link and eventually assess the impact of global change on stream biota.

Contact for sub-project 2
Dr. Jens Kiesel,
Tel: +49 (0)30 6392 4086 or +49 (0)9742 931077, Website

Sub-project 3: Improvement of climate change projections for benthic invertebrates

Existing models for species range changes will be improved by adding riverine characteristics and stressor functions
Sub-project 3 details

There is a lack of suitable models predicting ecological effects of global change for the riverine environment and to guide management decisions. While it would be tempting to actually measure potential range shifts and community changes by long-term analyses, these data are often geographically restricted and involve costly and time-consuming observation and quantification of species in the field. As an alternative, species distributions models (SDMs) are valuable tools for predicting and evaluating species range changes under global or climate change. However, large-scale modeling approaches have not considered riverine characteristics sufficiently.

The aim is thus to integrate stream specific data into SDMs: At the model building stage we aim to include variables like stream networks, water temperatures, hydrological / hydraulic variables, land use / land use past, upstream/lateral influences. From the biotic side we aim to include parameters like vegetation cover, life stages of insects, or categories of dispersal ability (e.g. terrestrial, aquatic, aerial dispersal). At the projection stage we aim to include stressor functions in projection areas, reflecting that organisms even while dispersing successfully, might encounter establishment problems.

Contact for sub-project 3
Katherine Irving,
Tel: +49 (0)30 6392 4089, Website

Sub-project 4: Analysis of flow related changes at large spatial scales

Investigation of climate change impacts on aquatic invertebrates on a continental or global level allows better understanding changes along gradients
(Project start in 2016)
Sub-project 4 details

The analysis on data rich model catchments from three important ecoregions in Germany (lowland, mountainous, alpine) will be complemented by analyzing large-scale flow changes and their ecological effects. Depending on the data availability the focus region might be a north-south European gradient from the Mediterranean to the Scandinavian region, but preferably a global approach will be sought. The regions chosen are expected to react differently to global change (i. e. increase/decrease in mean annual precipitation or enhanced summer droughts) and thus allow a comprehensive overview on potential effects.

It is planned to obtain macroinvertebrate data from rivers where flow characteristics have been altered. Such preferred sampling areas have been identified by modeled river flow alterations due to dams and water withdrawals as computed by the global water model WaterGAP. Furthermore, regions with semi-arid and conditions will be identified, where strong influence of water flow variations on freshwater biota is always expected.

Contact for sub-project 4
Martin Friedrichs,
Tel: +49 (0)30 6392 4082, Website