AquaPLAN researchers Leiden University open artificial river to study fish migration

AquaPLAN researchers at Leiden University (ULEI) have launched their MIGRADROME, a seven-metre-long artificial river they’ll use to investigate the impacts light and noise have on migratory freshwater fish. The artificial river is a water-filled glass tunnel-shaped tank that has cameras and speakers installed. The MIGRADROME is a unique research facility. Inside the tunnel tank, there’s another tank that is adjustable, it can be tilted to simulate different river flow rates and both natural and artificial light and sound conditions can be meticulously controlled.

“Migratory fish are struggling, from eels to salmon – their numbers are declining rapidly. Physical barriers like dams and sluices are well known, but light and sound can also block their path. Now we can finally test how and when that happens,” says Hans Slabbekoorn, AquaPLAN researcher and professor of behavioural ecology. “We want to find out how willing fish are to migrate under certain circumstances, how strong is their drive to migrate when there’s light pollution? What happens when a boat passes by? These are the kinds of questions we can now answer properly, if we understand what’s holding fish back, we can give better advice”. 

The MIGRADROME images are by Christi Waanders (ULEI)

The team’s main goal with the MIGRADROME is to help restore freshwater species, one of the most threatened groups worldwide. More than 50% of the world’s population lives within 3km of a freshwater habitat (Kummu et al. 2011) and as population densities increase, these freshwater habitats and species will face further significant changes in both light and noise pollution (LNP).

In AquaPLAN within the MIGRADROME, ULEI will test freshwater fish, including sticklebacks (Gasterosteus aculeatus), eel (Anguilla anguilla), ide (Leuciscus idus), and sturgeon (Acipenser sturio/ruthenus) in migratory mode for the impact of light and sound conditions on movement decisions. Both natural soundscapes and vessel sounds (with a variety of engine types, cargo sizes, propeller cavitation, and cruising speeds) will be employed. It’s hoped that combining observations and experiments conducted both indoors and outdoors will provide basic insights into the presence and location of light and sound sources in relation to passage bottlenecks, leading to cost effective solutions for increasing the passage rates of a wide range of threatened freshwater fish species. AquaPLAN is producing the first ecological time series relating freshwater, estuarine and marine biodiversity changes to combined LNP by starting a novel long-term monitoring programme based on dual stressor risk maps and harmonised protocols for quantifying LNP.

Learn more, read the original ULEI article

Kummu, M., De Moel, H., Ward, P. J., & Varis, O. (2011). How close do we live to water? A global analysis of population distance to freshwater bodies. PLoS ONE, 6(6), e20578. DOI: https://doi.org/10.1371/journal.pone.0020578