This work was supported by the National Natural Science Foundation of China (no. 31600315), the Postdoctoral Research Foundation of China (nos. 2017M612559, 2017M611939), the Opening Fund of the State Key Laboratory of Freshwater Ecology and Biotechnology (grant no. 2018FB08), the Science and Technology Plan of Changde City: Research on Light Stress of Freshwater Diatoms, and the Doctoral Start-up project of Hunan University of Arts and Science (no. 16BSQD30). The authors thank Dr. Qiang Yang (Trinity College, Dublin) for their valuable comments. The authors thank Dr. Lingling Zheng (FACHB, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan) for offering technical support in diatom isolation.