Response of the chironomid community to late Holocene climate change and anthropogenic impacts at Lake Ulungur, arid Central Asia

Lake ecosystems in arid Central Asia are in crisis due to water abstraction and eutrophication, and it is important to understand their response to combined climate and human impacts. In this study, based on the relationship between modern chironomids and salinity, we studied subfossil chironomid remains in a similar to 4550-year sedimentary record from Lake Ulungur in northwest China, with the aim of reconstructing past ecosystem dynamics, especially in response to climate change and human impacts. The results show that from 4550-580 cal yr BP the hydrological status of Lake Ulungur was transformed from close to open and the salinity decreased causing an increase in freshwater chironomid species. Comparison with regional paleoclimatic records makes us to infer that the lake ecosystem evolution has been primarily controlled by changes in the westerly driven by the Northern Hemisphere insolation. Since 580 cal yr BP, the lake returned to be closed and the structure of the aquatic community reorganized. In recent centuries, human activities have made a more significant effect on lake ecosystems in northwest China than natural climate changes, which largely was induced by a surge in the human population related to national policies. Furthermore, due to the combined effects of global warming and intensifying human activities, lake ecosystems in Central Asia are subject to unprecedented anthropogenic pressures and urgent action is needed to protect them.

Automated summary

Lake ecosystems in arid Central Asia are facing crisis due to water extraction and eutrophication, with significant impacts from both climate change and human activities. The evolution of Lake Ulungur over the past 4550 years has been influenced by changes in hydrological status, salinity, and freshwater chironomid species, primarily driven by Northern Hemisphere insolation and human population surges related to national policies. Urgent action is needed to protect lake ecosystems in Central Asia from the unprecedented anthropogenic pressures caused by global warming and intensifying human activities.