Research interests

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Research focuses on the diversity and variability of structures and key functions of freshwater ecosystems at different spatial and temporal scales. We mainly investigate two types of running waters: lowland sandy-bottomed streams and karst streams. Core features of sandy streams are the harsh shifting sand, the mostly immobile woody debris as well as tree roots as the only hard substrates, and allochthonous inputs of coarse particulate organic matter. Karst streams in contrast are characterized by their temporary character, causing at the reach scale more or less predictable flow intermittency and habitat fragmentation due to stream drying. At the local scale, shrinking and expansion of the water body is a typical phenomenon exerting hydraulic stress on the biota.

Phenomenological studies, field and laboratory experiments, and statistical data processing are integrated (i) to understand how the spatial and temporal variability of the respective environmental conditions affect patterns and dynamics of regional biodiversity, (ii) to enlighten the underlying mechanisms, and (iii) to make predictions with respect to climate change scenarios.

Basic research aims to answering questions emerging from human impacts on running water ecosystems.

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The research is conducted across different levels of biological hierarchy and addresses the following topics:

Species level (individuals and populations)

• species traits including life history and population dynamics of selected benthic invertebrate species

• behavioural stress response and cellular stress response of selected invertebrate and fish species

• adaptation to the variable and dynamic environmental conditions, and trends with respect to global warming (e.g., fitness consequences).

Community level

• spatial and temporal patterns of benthic invertebrate communities, hot spots of regional biodiversity

• controlling factors and relevant scales of invertebrate biodiversity in karst and sandy-bottomed streams

• dispersal and metapopulation structure of amphipods in fragmented temporary streams

• invasion biology.

Ecosystem level

• food web interactions and energy transfer

• decomposition of leaf litter and wood

• oxygen and nitrogen metabolism in sandy-bottomed and streams and gravel streams.

Tropical and boreal freshwater ecology

Biodiversity patterns and ecosystem functions encountered in temperate regions are compared to tropical and boreal streams, rivers, and lakes (Costa Rica, Guatemala, Colombia, Chile, Peru, Russia).

Applied limnology

• contributions to planning concepts and control of success of restoration projects

• conceptual design and performance of monitoring projects
  (e.g., habitat quality of Atlantic salmon (Salmo salar) redds with respect to oxygen conditions and substrate composition)

• development of appropriate methods, etc..