Relationship between water quality and phytoplankton biomass in Microcystis-laden raw water under silver carp filter-feeding

Silver carp were stocked in a pre-sedimentation pond in front of conventional water treatment processes in order to control Microcystis blooms in raw water. Silver carp effectively reduced the Microcystis flos-aquae concentrations, but green algae concentrations increased due to the ineffective filtration of silver carp for them. Water quality variations based on the effect of silver carp stocking on the two major phytoplankton communities (Microcystis and green algae) were evaluated by to investigate the relationship between water quality and phytoplankton cell concentrations in influent and effluent during Microcystis blooms period. Linear regression analysis indicated that the dominant species Microcystis governed the variation of turbidity and COD _Mn, and its concentration showed positive correlations with the two parameters. Meanwhile, the increase of green algae biomass led to the increase of pH and Chlorophyll a content, and showed obvious positive correlations with the two parameters in effluent.