RESEARCH PROGRESS ON WATER BLOOM IN TRIBUTARY OF THE THREE GORGES RESERVOIR

Since the impoundment of the Three Gorges Reservoir (TGR) in 2003, its ecosystems have changed significantly, and water bloom in the tributary has become a major ecological and environmental issue of great concern. This paper reviews the research progress on the succession pattern of phytoplankton community and tributary water bloom over the past 20 years since the impoundment. It has been confirmed that the phytoplankton community in the tributaries of TGR is dominated by Chlorophyta, Cyanophyta, and Bacillariophyta, with distinct spatial variations and seasonal characteristics observed across different tributaries. The dominant bloom species include Cryptophyta, Bacillariophyta, Dinophyta, Chlorophyta, and Cyanophyta. The dominant species changed with the reservoir storage operation stage, and the current dominant species are Cyanophyta and Bacillariophyta, with <italic>Microcystis</italic>, <italic>Pseudanabaena</italic>, <italic>Cyclotellae</italic> being prevalent. The water bloom in tributaries mainly occur in the spring and summer, with peak occurrence during flood season and drawdown period. In addition, the frequency of tributary water bloom in Chongqing area is higher than that in Hubei area, and the total frequency of water bloom show a decreasing trend after 2015. Hydrodynamics, temperature, and nutrients are the main factors influencing the water blooms. A comprehensive prevention and control technology system, encompassing physical, chemical, and biological approaches, has been developed and implemented for the TGR tributary water bloom. This system has played a pivotal role in mitigating water blooms and has achieved significant results. However, given the serious ecological and environment threats posed by the tributary water bloom, future research should focus on intelligent monitoring and early warning systems, as well as efficient prevention and control strategies, so as to provide theoretical basis and technical support for safeguarding the ecological environment safety and sustainable utilization of the TGR.