Coupling of light and nutrients affects Microcystis gas vesicle content at different depths

Abstract

Abstract Lakes are important water resources for human beings, but Microcystis blooms pose a serious threat to drinking water security and aquatic ecosystems. Gas vesicles (GVs) are an important trigger for the occurrence of Microcystis blooms. To understand the effects of light and nutrients on GV content, the phytoplankton in Lake Erhai were investigated. The results showed that the average GV content in the surface water was higher than that in the deep water. The total nitrogen in water affected the GV content by limiting the protein content, and the content of GVs increased by 9.2 μm3/cell for each 1.0 pg/cell increase in the intracellular nitrogen content. Moreover, light and total phosphorus affected the GV content in deep water by limiting the energy supply, and the content of GVs increased by 52.4 μm3/cell for each 1.0 pg/cell increase in the intracellular phosphorus content. These results indicate that for lakes with low transparency, decreasing the total phosphorus concentration can reduce the GV content. Reducing the total nitrogen concentration can reduce the GV content and decrease the dominance of Microcystis in all lakes. This study provides useful information for the control of Microcystis.