Ecological influences affecting the distribution of larval chironomid communities in the lakes on Yunnan Plateau, SW China

Abstract

Surface sediment samples were collected from 35 lakes on the Yunnan Plateau as part of an investigation into the relationship between surface sediment subfossil chironomid distribution and lake environmental variables. This region of China is unique as it contains large temperature gradients, from the subtropics to the foothills of the Himalaya, but also contains lakes that have been heavily impacted by anthropogenic activities. The chironomid communities were dominated by 8 taxa, which together accounted for 77.7 % of the fauna. The statistical analyses indicated that mean July air temperature and water depth were the most significant variables affecting the distribution of chironomids across these sites. After removing 3 major outliers from axis 1 in the ordination data set, temperature lost its significance but water depth and reductions in bottom dissolved oxygen (DO) were still found to be significant. In addition the diversity of the dataset was found to be low compared with other chironomid training sets throughout the world, suggesting that this region in China has different characteristics governing the abundance and distribution of chironomids compared with other parts of the world, hence the need for regional training sets within China. This is the first subfossil chironomid data set from this region and the understanding of key environmental influences on contemporary faunas will aid interpretations of palaeolimnological data sets to reconstruct past trends and magnitude of environmental change over a range of timescales.