Author(s): Maria Joao Costa; Francisco Godinho; Filipe Romao; Juan Francisco Fuentes-Perez; Jeffrey A. Tuhtan; Isabel Boavida
Linked Author(s): Juan Francisco Fuentes Perez
Keywords: No Keywords
Abstract: Hydropeaking generates abrupt sub-daily fluctuations that alter river hydraulics and morphology, affecting fish populations and their respective habitat use. Understanding how small-bodied leuciscids respond to these pressure-driven flow changes at the microhabitat scale remains difficult. However, fish use the lateral line system to detect hydrodynamic changes in their surroundings through local changes in pressure. Traditionally, fish–habitat relationships are described by microhabitat use metrics (depth, substrate, velocity), but these often overlook fluid-body interactions that fish use to sense and respond to the flow field. This study related fish detections (presence vs. avoidance, presence vs. avoidance vs. mobility) to hydrodynamic conditions immediately after a pulsed-flow event downstream of a small hydropower plant. A 150-m reach was surveyed, 133 PIT-tagged leuciscids were tracked over five days, and three pressure-derived variables were measured with an artificial lateral line, representing streamwise flow (front pressure), turbulence (front fluctuations) and cyclic flow patterns (pressure asymmetry). The analysis identified pressure asymmetry and pressure fluctuations as the main drivers of fish presence, showing that fish were consistently present in microhabitats with lower asymmetry and fluctuations. These results highlight the value of this non-invasive pressure-sensing technology for quantifying the hydrodynamic conditions that drive habitat selection in hydropeaking-impacted rivers.
Year: 2026