Freshwater ecosystems are amongst the most threatened ecosystems on earth and the threats they face also extend to the migratory fish using them. This is likely due to a multitude of stressors and a sequential dependency of migratory fish on the typically narrow and linearly shaped river systems without spatial alternatives. Not only are they caught for consumption, blocked by barriers (such as weirs, dams, and locks), but they are also confronted with an altered underwater riverscape of artificial light at night and traffic noise from boats, nearby roads and the daily rhythm of human activities.
We know there are problems for fish during their migration, but we do not know to which extent they are determined by light and sound conditions, or to which extent smart solutions may exist to reduce problems at migratory bottlenecks. We also do not know how typical diurnal or nocturnal migrants respond to artificial light at bifurcations or river stretches, or how they react to the fluctuations of sound level and spectra during passages through cities or under bridges. At Leiden University, we study the underwater light- and soundscapes in Dutch river systems, and we test impact of field conditions in the laboratory, using the newly built MIGRADROME, a 7 meter long swim tunnel, in which we can manipulate light and sound conditions, as well as the speed and gradient of the water velocity.
We are looking for a talented and motivated PhD candidate that will explore the combined effects of light and noise pollution on migratory fish in outdoor and indoor conditions. This PhD-project is part of a large consortium funded by the EU-HORIZON-project AquaPLAN, and follows up on PhD-projects on the effects of light pollution on the biological clock of migratory fish (within the NWO-NWA-funded BIOCLOCK-project) and the effects of vessel noise on swimming behaviour of migratory fish (EU-HORIZON-project SATURN). Key tasks
- Design and execute sampling efforts on environmental light and sound conditions in combination with presence and behaviour of local and migratory fish communities
- Conduct controlled exposure experiments in the MIGRADROME to test combined effects of multiple stressors on migratory tendencies of various fish species