THEMATIC ISSUE Distribution of Ephemeroptera, Plecoptera, and Trichoptera assemblages in relation to environmental variables in headwater streams of Mongolia Dashdondog Narangarvuu • Jargalsaikhan Oyunbileg • Ping-Shih Yang • Bazartseren Boldgiv Received: 15 June 2013 / Accepted: 16 November 2013 / Published online: 10 January 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract Effects of stream environmental variables on the distribution and abundance of Ephemeroptera, Ple- coptera and Trichoptera (EPT) assemblages in the head- waters of rivers and streams of Mongolia were investigated in this broad scale survey aimed to provide a baseline for future research and management of the country’s aquatic ecosystems. The survey was carried out in the first-, sec- ond- and third-order streams of 80 rivers selected from the three main watersheds of Mongolia, namely the Arctic Ocean Basin (AOB), Pacific Ocean Basin (POB) and Central Asian Internal Basin (CAIB). We sampled larvae of EPT by kick and D-nets from the headwater sites during summers of 2007–2009. Chemical and hydrological vari- ables of the sites were measured, and habitat of those sites was assessed. We recorded 89 taxa belonging to 34 fami- lies of EPT orders during the survey. The family Baetidae (Ephemeroptera) was the dominant taxon among all sites. Taxon richness was higher in the POB and AOB than CAIB, while total EPT abundance was higher in the CAIB. Significant differences in the community variables, such as taxon richness, Shannon’s diversity index and evenness of EPT assemblages were observed among the basins. Results of canonical correspondence analysis suggested that alti- tude, dissolved oxygen, order and width of streams were the most important factors explaining the variability in EPT larval distribution in the headwater streams in Mongolia. Keywords Ephemeroptera Á Plecoptera Á Trichoptera Á Mongolia Á Arctic Ocean Basin Á Pacific Ocean Basin Á Central Asian Internal Basin Á Aquatic ecosystem health Introduction Aquatic macroinvertebrate assemblages can be affected by various local and regional environmental factors, such as chemical and physical characteristics of stream water, hydrology, and geographical location, as well as climatic factors (Malmqvist 2002; Heino et al. 2003; Vannote et al. 1980; Zamora-Mun ˜oz et al. 1993; Bispo et al. 2006; Heino 2012; Sandin and Johnson 2004). Spatial and temporal variability of these factors largely determine the macroin- vertebrate communities in stream ecosystems (Baptista et al. 2001). Among the macroinvertebrates, orders Ephemeroptera, Plecoptera and Trichoptera (EPT) are highly diverse insect assemblages in the headwater cobble streams (Bispo et al. 2006) with important roles in trophic transfer (Merritt et al. 2008). They are sensitive to distur- bances and their diversity is often considered as an indi- cator of good quality of the ecosystems (Rosenberg and Resh 1993). Human activities such as climate change, livestock herding, agriculture, deforestation, unregulated urban and industrial development and irresponsible mining have negatively affected the environment of Mongolia. In recent D. Narangarvuu Á P.-S. Yang Department of Entomology, College of Bio-Resource and Agriculture, National Taiwan University, Taipei 106, Taiwan, ROC D. Narangarvuu (&) Á B. Boldgiv (&) Department of Ecology, School of Biology and Biotechnology, National University of Mongolia, Ulaanbaatar 210646, Mongolia e-mail: garvuu@gmail.com B. Boldgiv e-mail: boldgiv@num.edu.mn J. Oyunbileg Ecology Education Center, National University of Mongolia, Ulaanbaatar 210646, Mongolia 123 Environ Earth Sci (2015) 73:835–847 DOI 10.1007/s12665-013-2968-9