Spatially different nutrient histories recorded by multiple cores and implications for management in Taihu Lake, eastern China

The Taihu Lake, a large shallow lake in the floodplain of the Changjiang (Yangtze) River in the eastern China, is faced with challenging ecological problems resulting from eutrophication, which has affected the regional freshwater supply of a large population. Although efforts have been made to assess the nutrient evolution histories in the northern bays, little is known regarding nutrient histories in different parts across the entire lake basin. In this paper, we present nutrient histories for different parts of the lake based on chironomid transfer functions applied to four short cores obtained from the northern, western and eastern regions of the lake. The chironomid-inferred total phosphorus (CI-TP) concentrations were compared with the phosphorus concentrations obtained by using instrumental and sedimentary data. The results suggest that trophic evolution histories were asynchronous throughout the lake during the past decades in response to different ecological regimes controlled by the nutrient input, wind direction and shoreline topography. The restoration of aquatic plants may be an effective option for the management of lake rehabilitation to ‘natural’ conditions. Given the multiple factors controlling the biotic communities in such a large and complex lake, combined analyses among the multi-proxies encountered in the sediments are necessary for comprehensive insight into paleolimnological studies. The spatial heterogeneity in the ecological trajectories within this complicated ecosystem suggests that different management practices should be undertaken for specific lake zones in the Taihu Lake.