Effects of wind and wind-induced waves on vertical phytoplankton distribution and surface blooms of Microcystis aeruginosa in Lake Taihu

Effects of wind and wind-induced waves on vertical phytoplankton distribution and Microcystis aeruginosa bloom formation were studied in Meiliang Bay of Lake Taihu from September 5 to 9, 2004. Concentrations of chlorophyll a, b, and phycocyanin in the water column were used to represent the abundance of total phytoplankton, chlorophytes, and cyanobacteria, respectively. Water samples were taken under different wind and wind-induced wave conditions. Ca. 90% of Microcystis aeruginosa had densities less than that of lake water and were thereby positively buoyant. Vertical distributions of total phytoplankton, chlorophytes, and cyanobacteria were markedly affected by wind and waves, with coefficients of variation of pigment concentrations throughout the water column showing a negative correlation with increasing wind and waves. Surface proportions of M. aeruginosa versus total amounts in the water column also closely correlated with wind and waves, which demonstrated that wind and waves directly influenced surface M. aeruginosa blooms in Lake Taihu. A less significant correlation was found for total phytoplankton, but there was no correlation for chlorophytes in the water column.