Anthropogenic turbulence and velocity barriers for upstream swimming fish: A field study on emerald shiners (Notropis atherinoides) in the Upper Niagara River

Anthropogenic modifications alter the hydrodynamics of rivers and can affect the movement of aquatic organisms. The upper Niagara River is home to a trophically important minnow species, the emerald shiner (Notropis atherinoides) who appear to have difficulty traversing a stretch of the shoreline seawall along Broderick Park, Buffalo, NY, USA. The goal of this study was to determine if the upstream movement of emerald shiners was affected by the current hydrodynamic conditions along the US shoreline at Broderick Park in the Niagara River. Field point- velocity measurements were collected using an Acoustic Doppler Current Profiler and Acoustic Doppler Velocimeter along the US shoreline of the upper Niagara River adjacent to Broderick Park. Results indicate that this highly modified stretch of the shoreline is characterized by velocities beyond the swimming capability of emerald shiners (0.59 m s-1) and turbulence conditions that are not conducive to fish movement as quantified by turbulent kinetic energy, Reynolds shear stress, integral length scales and the energy associated with eddies of a problematic size range (55- 400 mm). Therefore, the seawall upstream of the shoreline recess along Broderick Park is likely to be a barrier to the upstream passage of emerald shiners into Lake Erie. This study also provides an effective method to determine the location of potential barriers to fish passage.