Longitudinal patterns of macroinvertebrate communities in relation to environmental factors in a Tibetan-Plateau river system

As the water source of Asian several largest rivers, the numerous Tibetan-Plateau systems support a unique but still unexplored biodiversity. This paper investigates one such river to examine the longitudinal variations of macroinvertebrate richness and composition, and identify the assemblage-environment associations. Altogether 94 taxa belonging to 38 families were identified. Chironomidae was the species-richest and numerically-dominant group, followed by Trichoptera and Ephemeroptera. Taxon richness, Shannon–Wiener diversity and EPT composition significantly decreased downstream, but composition of Chironomidae and Oligochaeta increased. Canonical correspondence analysis showed that five environmental factors including substrate, channel width, current velocity, total suspended solids and turbidity were significant predictors of the community variance. This study gives new taxonomical and ecological information on lotic macroinvertebrate assemblages in a poorly-known high altitude region.