The researchers studied the zooplankton and phytoplankton in a reservoir in the Three Gorges region. They found that the types of plankton and their abundance changed with the seasons. Phytoplankton were most abundant in summer, while zooplankton peaked in spring. The water quality was best in winter and spring but worse in summer, indicating the reservoir was somewhat polluted. Factors like nutrients and oxygen levels affected the plankton communities.