Influence of environmental parameters on the distribution of subfossil chironomids in surface sediments of Bosten lake (Xinjiang, China)

The distribution of larval subfossil chironomids in surface sediment samples obtained from Bosten lake was analysed, and ordination methods were used to identify the influences of physical and chemical parameters on the abundance and diversity of chironomids. A total of 18 chironomid taxa was identified across the 32 samples, 15 of which showed minimum abundance of >1% and were present in more than one site. Chironomus plumosus-type, Microchironomus and Tanytarsus glabrescens-type were the most abundant of the 18 chironomid taxa identified. The distribution of the main chironomid species within Bosten Lake exhibited spatial heterogeneity. T. glabrescens-type was found to dominate Huangshuiwan, in the northwest part of Bosten lake, which had higher salinity and organic content. Microchironomus was mainly distributed in the Kaidu river mouth, in the southwest part of Bosten lake, whereas C. plumosus-type was more abundant in the deep centre, suggesting the importance of water chemistry, water dynamics and water depth on chironomid distribution. The relationship of chironomid distribution with environmental parameters was assessed using redundancy analysis, and the results revealed that water depth, Secchi depth and salinity were the predominant factors influencing chironomid distribution; these factors could explain the chironomid variances of 18.3, 5.3 and 5.0%, respectively. Our surface sediment-derived data provide a baseline for the analysis of future environmental variations of the lakes in the arid regions of northwest China, which are threatened by impacts of global climate change and regional water management.