Spatial and temporal variations in algal phosphorus in Taihu Lake

Phosphorus circulation in Taihu Lake has attracted extensive attention, but the contribution of Microcystis to phosphorus circulation in this area is unknown. In this study, the phosphorus concentrations in algal samples collected from the lake in 2015–2016 were determined in the laboratory. From the concentration data, the total quantity of algal phosphorus was calculated and the seasonal variations in algal phosphorus were examined. The results indicated that the intracellular phosphorus content of Microcystis in Taihu varied from 0.044 to 0.130 pg/cell and tended to be high in spring and low in summer. The total amount of algal phosphorus in Taihu Lake ranged between 7.78 and 97.32 t over the study period. Algal phosphorus only accounted for between 1.5 and 18.5% of the phosphorus stock in the water. Because Microcystis accumulated downwind, there was a tendency for the total phosphorus concentrations to be low in the east of the lake and high in the west of the lake. This new information about the spatial and temporal distribution of algal phosphorus contributes to our understanding of how phosphorus in Microcystis contributes to phosphorus circulation in Taihu Lake.