EGU General Assembly 2023
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Stranding of early cyprinid life stages: effects of artificial flow down-ramping on Barbus barbus L. and Chondrostoma nasus L. under experimental conditions

Simon Führer1, Daniel S. Hayes1, Thomas Hasler1, David R. M. Graf1, Felix Stoisser1, Elora Fauchery2, Anna Coudrais2, Antonin Olejarz2, Daniel Mameri3, Stefan Schmutz1, and Stefan Auer1
Simon Führer et al.
  • 1University of Natural Resources and Life Sciences, Vienna, Institute of Hydrobiology and Aquatic Ecosystem Management, Department of Water, Atmosphere and Environment, Austria (
  • 2Graduate School of Engineering, University of Tours, Tours, France
  • 3Forest Research Centre (CEF) and Associate Laboratory TERRA, School of Agriculture, University of Lisbon, Lisbon, Portugal

Artificial sub-daily flow fluctuations caused by peak-operating hydropower plants are considered one of the most significant impacts on riverine ecosystems downstream of dams. These rivers have, therefore, been subject to numerous studies in recent decades. However, cyprinid fish, in contrast to salmonids, have hardly been addressed in hydropeaking studies yet, and extensive knowledge gaps remain. Therefore, our experimental study aims to assess the effects of rapid flow reductions on the early life stages of two European cyprinid indicator species, the common barbel (Barbus barbus L.) and the common nase (Chondrostoma nasus L.).

We conducted mesocosm experiments (2.25×2 m) under semi-natural conditions at an outdoor experimental facility (, simulating different hydropeaking scenarios with varying down-ramping rates during day and night. At each trial, 100 fish from one species (body length <20 mm) were stocked at peak flow (80 L.s-1). After an acclimation time (15 min.), the flow rate was reduced with variable ramping rates (0.3–1.8 cm.min-1) to constant low flow conditions (10 L.s-1). As a response parameter, larval stranding on a gently sloped shoreline mimicking typical nursery habitats was quantified during day and night.

The results reveal distinct diurnal patterns for both species, with increased stranding rates at night for all experimental scenarios. In addition, the data indicate differences between the tested down-ramping rates and show interaction effects between both parameters. The difference between species may result from water temperature and ecological factors. The study outcomes will benefit the ongoing discussion on species-specific hydropeaking mitigation by providing first insights on the direct effects of artificial flow down-ramping on early life stages of cyprinid fish.

How to cite: Führer, S., Hayes, D. S., Hasler, T., Graf, D. R. M., Stoisser, F., Fauchery, E., Coudrais, A., Olejarz, A., Mameri, D., Schmutz, S., and Auer, S.: Stranding of early cyprinid life stages: effects of artificial flow down-ramping on Barbus barbus L. and Chondrostoma nasus L. under experimental conditions, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5678,, 2023.