The researchers studied the types and amounts of tiny plant-like organisms called phytoplankton in the waters near the Yangtze River estuary. They found 135 different species of phytoplankton, with diatoms being the most common type. The amount of phytoplankton was highest in certain areas and decreased as they moved towards the lower part of the estuary. One species, Skeletonema costatum, was the most abundant, making up over 70% of all phytoplankton. The researchers also looked at factors that influenced the distribution of phytoplankton in the area.