Effect of flow velocity on phytoplankton biomass and composition in a freshwater lake

Abstract Water flow has been widely accepted as a target to suppress algae blooms. However, the effectiveness of the flow regulation is unclear due to lack of hard evidences to illuminate the direct cause–effect relationship between hydrodynamic forces and algae growth. In this study, a field observation at a freshwater lake was conducted weekly or biweekly from July 2007 to December 2009. Phytoplankton biomass and composition were investigated at flow velocities of 0.03 m/s, 0.06 m/s, 0.10 m/s, 0.15 m/s and 0.30 m/s in field enclosure experiments. The results from the field observation indicated that phytoplankton biomass and spatial distribution largely depend on the flow condition. A strong negative correlation (R 2  = − 0.618, n = 222, P