Eco-environmental evolution of a freshwater lake in a semiarid grassland from the perspective of Cladocera zooplankton: The impacts of climate change and human disturbance

Abstract

The ecological environment of grassland lakes is closely related to water security and human health in both arid and semiarid regions. The protection of freshwater and wetland ecological environments in grasslands promotes the stable and healthy development of ecosystems in arid and semiarid areas. In the present study, we investigated the long-term eco-environmental evolution of a typical grassland lake: Wulanpao Lake, located in the Hulun Lake Basin of northern China. This region represents the junction of areas subject to monsoons and those that are not and is arid or semiarid. We used the biological indicator of subfossil Cladocera, geochemical indices, and grain size from a well-dated sediment core. The ecological environment of Wulanpao Lake was influenced by climate change, consistent with a low trophic status, and the site developed aquatic vegetation between the 1860s and 1970s. However, the observed shift from predominantly littoral to planktonic Cladocera species was accompanied by ecological turnover (changes in the sedimentary environment and increases in trophic status and organic matter) when human activities began to impact the lake environment in the 1970s. This research provides an empirical foundation for managers and policymakers to protect similar grassland freshwater eco-environments.