The researchers studied how human activities like pollution and water changes have affected Chenghai Lake in China over 250 years. They looked at sediment records and recent data to see how the lake's ecosystem changed. They found that nutrient levels in the lake increased a lot after 2000, leading to more plant growth. Water projects in the 1990s made the lake more turbulent, which helped certain types of algae grow. The lake's carbon cycle was mostly influenced by things inside the lake. Overall, the lake's ecosystem was mainly affected by pollution and water changes, showing the need for better management to protect the lake's health.