Lake Taihu and the catchment are one of the economic and cultural centre areas of China, and play an important role in the sustainable development of Yangtze River Delta and Eastern China. Assessments of ecosystem health of Lake Taihu from 1960 to 2005 were conducted using both individual and aggregated biological indicators. Concentrations of total phosphorus (TP), total nitrogen (TN), and chemical oxygen demand (COD) in 2000 were 2-10 fold higher than those in 1960, rendering a decline in water quality from Class I – II to Class IV. Trophic state index (TSI) increased from 35 in 1960 to greater than 50 in 1990s, confirming the change in trophic state of Lake Taihu from oligotrophy to eutrophy. These changes in water quality have led to corresponding changes in composition, density and biomass of many aquatic organisms. Algal blooms occurred in high frequency since the late 1980s, which also led to the dominance of small zooplankton and benthic invertebrates. Approximately 41 species of fish have disappeared from the lake since the late 1960s. Buffer capacity (BC) of phytoplankton and zooplankton increased but benthic animals decreased. The Lake Taihu ecosystem was in better health state in 1960s than that in the past twenty years, evidenced by high abundances of macro-benthos, large zooplankton and submerged plants. Poor health state is essentially due to water quality deterioration induced by increasing human activities, which further resulted in the loss of most of the service functions during the past 20 years. All the indicators directed the year of 1992 is an important overturn point during the lake’s health dynamics.
Results/Conclusions
Based on the historical rebuilding and coordination of the area, population, aquatic environment and biodiversity from 200 BC to present, we know that in the long history of this area, the human-induced driving has play an important role since Shui Dynasty and both the positive and negative effects enhanced while years passed. According to the fact, we got the human-induced mode and process which drives the ecological environment development, which provides us the practical possibility of human-induced treatment of the Lake Taihu in the future.
