The researchers studied the amount of chlorophyll-a in Yao Lake over a year. They found that chlorophyll-a levels varied between different areas of the lake and changed with the seasons. Chlorophyll-a increased in spring, summer, and autumn, but decreased in winter. The amount of chlorophyll-a was linked to factors like water temperature, dissolved oxygen, nutrients, and pH. Higher nutrient levels were associated with higher chlorophyll-a levels.