Integrating Studies on Chironomid (Diptera) Biological Diversity and Biological Assessment in the Selenge River Watershed, Mongolia

Biological assessment of Chironomidae (Diptera) from eight affluent streams of Lake Hovsgol, Mongolia is combined with diversity survey data from the Hovsgol region. The streams were sampled twice monthly from June through August of 2002 following methods modified from the U.S. EPA Rapid Bioassessment Protocol. All data were combined and analyzed against physical and habitat data by hierarchical cluster analysis. Physical and habitat features of the streams and their watersheds varied little with the exception of substrate and cattle density. Streams in Borsog valley with the lowest density of cattle also had the lowest diversity and abundance of chironomids; whereas Shagnuul gol, which flows through the valley with the highest density of cattle had much higher abundance and diversity and a very unique chironomid assemblage composed of Trichotanypus sp., Derotanypus sibiricus Kruglova and Chernovskij, Potthastia longimani group, and Acricotopus sp. The results of this study are compared to diversity data for the region. This study has resulted in seven new records of chironomids for Mongolia. However, previous qualitative and semi-quantitative sampling of some of the same sites produced markedly different chironomid communities. It is concluded that diversity and ecological sampling are both necessary for biological assessment.