The researchers studied the phytoplankton community and water quality in Lake Baiyangdian by sampling at eight sites. They found 133 species of phytoplankton, with green algae, cyanobacteria, and diatoms being the most common. In spring, green algae and diatoms were dominant, while in summer, green algae and cyanobacteria were dominant. The phytoplankton density increased significantly compared to previous years. The water in Lake Baiyangdian was mostly eutrophic, meaning it had high nutrient levels.