Keywords
Fieldwork, ecohydraulics, hydropeaking, dispersal, larval fish
Description
Fish move within rivers for many reasons, including spawning, feeding, and avoiding predators. Early life stages such as fish larvae, in particular, often rely on the river flow to move downstream, facilitating their dispersal. As a result, rapid changes in river flow, such as hydropeaking caused by hydropower operation, can negatively affect fish dispersal. While previous flume experiments have supported this hypothesis, no study has yet investigated the impacts of hydropeaking on larval fish dispersal in the field.
In 2025, the Ecohydraulics team at the Institute of Environmental Engineering (ETH Zurich) will carry out experiments to understand the effects of hydropeaking on the dispersal of brown trout larvae (Salmo trutta) in the Poschiavino river (GR). We will study dispersal by combining a cutting-edge underwater camera system (the Riverine Organism Drift Imager, RODI, see image) with electrofishing and tagging of fish with visual markers. Larval fish will be marked after they emerge from their nest in the gravel bed, and their subsequent dispersal in the river monitored. By marking the fish and using continuous image-based monitoring, we can reconstruct their dispersal pathways and quantify potential differences between hydropeaking and non-hydropeaking reaches.
We are looking for motivated students who are passionate about riverine ecosystems and are keen to undertake their studies in field settings to join our Ecohydraulics team in this project. You will perform up to 12 weeks of fieldwork with us, including setting up and maintaining RODIs, assisting during electrofishing, and supporting the marking of the fish larvae. After that, data analysis will be performed using computer vision and machine learning techniques. You will have the opportunity to shape your thesis according to your interests, with possibilities that might include identifying differences in dispersal between reaches, assessing which environmental conditions promote larval fish drift, or developing your own methodology for quantification of the sampled discharge based on the recorded videos.
Skills you will learn
You will gain hands-on experience conducting fieldwork in alpine rivers, combining hydraulic engineering with aquatic ecology. Additionally, you will apply computer vision and/or machine learning techniques to identify aquatic organisms in the video recordings and gain experience in applying statistics to field data.
Goal
The aim of the Master Thesis or Project is to measure the dispersal of brown trout larvae and identify differences between reaches affected by hydropeaking and residual flow reaches.
Project start
March 2025 or by arrangement
Location
Fieldwork: Poschiavo (GR)
Analysis: Environmental Microfluidics Laboratory, IfU, D-BAUG (ETH Zurich, Hönggerberg campus)
Project type
This project is available for multiple students who will work together in the field but analyze different aspects of the collected data. Fieldwork takes place over 12 weeks between April and July 2025, with the exact dates communicated by January 2025. The Ecohydraulics team covers fieldwork expenses. A driver’s license would be an asset but is not essential.
This Master thesis is also available as a Master project, with six weeks of fieldwork and reduced data analysis.
Contact details
Joël Wittmann (joelw@ethz.ch)
Dr. Luiz Silva (lumartins@ethz.ch)