The researchers studied phytoplankton in the Yangtze River Estuary and nearby waters in winter. They found 130 different types of phytoplankton, with Bacillariophyta and Dinophyta being the most common. The main species were Paralia sulcata, Skeletonema costatum, and Thalassiosira rotula. Phytoplankton abundance was higher near the shore and at the surface of the water. It was linked to nutrient levels like nitrate and phosphate, but decreased with higher salinity. Overall, the diversity of phytoplankton was higher in the central area of the study.