2) Student projects offered by Bernhard Wegscheider
Project 1
Mapping the shifting habitat mosaic of the Sense river
Braided rivers like the Sense are constantly reshaped by changing discharge. Riffles, runs, pools, gravel bars and side channels appear, shift and disappear, while the river as a whole maintains a diverse mosaic of habitats. This “shifting habitat mosaic” is thought to provide refugia and stabilise aquatic communities, much like a diversified portfolio buffers against risk. To test this, we sample macroinvertebrates at sites along the Sense and characterise the communities using DNA metabarcoding. In this Bachelor thesis, you will link the community data from our invertebrate monitoring to the drone derived habitat conditions at each site.
You will fly a drone at the sampling sites at different discharge levels to map mesohabitats and wetted versus dry areas, and document how the habitat mosaic changes as flow rises and falls. From these maps, you will develop a metric of habitat heterogeneity that captures both the diversity of habitats and how they change with discharge. You will then relate it to the metabarcoding data, to test whether sites with a more heterogeneous and dynamic habitat mosaic support more diverse invertebrate communities, and whether community composition shifts differently between seasons. The project combines field work, drone-based remote sensing, GIS analysis and molecular community ecology. It is part of our wider research on how habitat heterogeneity creates resilience in river ecosystems.
Project 2
Recovery of invertebrate communities and their nutritional quality after an artificial flood in the Saane river
Hydropower dams dampen the natural flood regime of rivers. Less bed load is moved, the substrate clogs and becomes overgrown with algae, and habitat heterogeneity declines. Benthic invertebrate communities in regulated rivers are therefore often less diverse and differently composed than in free-flowing rivers, which may also lower their nutritional value for fish, for example their content of omega-3 fatty acids. Artificial floods are increasingly used to restore natural disturbance in regulated rivers, but it is poorly understood how invertebrate communities and their nutritional quality respond, and whether they move towards the state of a natural river. This thesis uses an experimental flood in the regulated Saane to follow this response, with the near-natural Sense as a reference.
You will analyse invertebrate samples from the Saane taken before the flood, and at several time points after the flood, and compare them with reference samples from the Sense, a near-natural river. You will identify invertebrates morphologically to quantify richness, abundance and community composition, and measure the fatty acid content of dominant taxa. The analyses address three questions: How does the Saane community differ from the Sense? What are the immediate effects of the flood? And does the Saane community converge towards the Sense during recovery, beyond normal seasonal change? The project offers training in river field sampling, invertebrate identification, fatty acid analysis and community analysis in R. It is part of a larger project on how temperature and habitat heterogeneity shape invertebrate communities and food quality for fish in pre-Alpine rivers, in collaboration with the University of Bern.
Requirements: Strong interest in freshwater ecology, conservation and restoration of river ecosystems, and quantitative analysis. Willingness to conduct fieldwork in riverine environments. The project can be started in autumn 2026.
Contact:
Dr. Bernhard Wegscheider, University of Bern, Institute of Ecology and Evolution; bernhard.wegscheider@unibe.ch
Prof. Dr. Ole Seehausen, University of Bern, Institute of Ecology and Evolution; ole.seehausen@unibe.ch
