The important role of controlling water velocity and benthic fish in lake eutrophication restoration

Eutrophication has emerged as a significant environmental challenge confronting freshwater lakes globally, largely driven by increased human activities. This study utilizes a combination of in situ simulations and field validation experiments to systematically evaluate the disturbance effects induced by water velocity and benthic fish on lake water quality and aquatic vegetation. We explore the potential of managing water velocity and benthic fish as effective ecological technologies to mitigate endogenous pollution, enhance lake water quality, and promote the growth of submerged plants. Our findings demonstrate that the disturbance of two factors lead to a substantial increase in suspended particulate matter (SPM) ranging between 2 to 10 μm, which is the primary cause of diminished water transparency and the yellowing of water color. Notably, there is a critical velocity threshold under the conditions of this study: between 0.6 × 10 −3 m/s to 1.2 × 10 −3 m/s, algal growth is inhibited, whereas sediment resuspension occurs at flow velocities ranging from 1.2 × 10 −3 m/s to 1.8 × 10 −3 m/s. Our results indicate that reducing flow rates and controlling benthic fish populations can significantly lower fine particle concentrations, decrease nutrient levels, and mitigate algal biomass and odor release, thereby fostering the growth of submerged aquatic vegetation (e.g. Vallisneria natans ). These findings offer valuable insights for the ecological management of similar lakes and provide essential guidance for the restoration and protection of comparable ecosystems.