Taxonomic and functional diversity differentiation of chironomid communities in northern Mongolian Plateau under complex environmental impacts

We analyzed the taxonomic and functional diversities of chironomid communities on the northern Mongolian Plateau to understand the responses to multiple environmental pressures. The 27 lakes studied were classified into three groups based on significant heterogeneity of habitats. A total of 65 chironomid taxa were identified with the dominant taxa being Chironomus pallidivittatus-type, Cricotopus sylvestris-type and Glyptotendipes pallens-type. Our redundancy analysis revealed that temperature, salinity and oxygen concentrations are the main factors influencing the functional feeding traits of the chironomids. Taxonomic and functional alpha diversities show a significant positive relationship across the lakes. Taxonomic alpha diversity is more responsive to the environmental variables in low-altitude freshwater lakes. In contrast, functional alpha diversity contributes to a better understanding of the relationship between chironomid communities and environmental factors in high-altitude freshwater and low-altitude brackish lakes. The decomposition components of overall beta diversity respond differently to taxonomy and function. The turnover component predominates in taxonomic beta diversity, while the nestedness component plays a more important role in functional beta diversity. Our study suggests that taxonomic and functional beta diversities and their partitioning components can be used as a reference for the aquatic biodiversity protection and ecological management in arid and semi-arid regions.