Disturbed aquatic habitats in central-eastern Inner Mongolia revealed by the prevalence of widespread ostracod species

Despite previous scientific investigations on the limnic ostracods in eastern Inner Mongolia, the ostracod assemblages in aquatic habitats other than the large brackish lakes in this region have been poorly studied, hampering comprehensive knowledge of the regional ostracod fauna. Here we analyze the ostracod assemblages in various surface waters in central-eastern Inner Mongolia, including the abundant ponds formed due to road construction that are otherwise rare on the grassland, as well as natural swamps, lakes, and running waters. A total of 19 species of living ostracods are recovered, with the ponds dominated by Heterocypris incongruens and Ilyocypris mongolica, swamps by Physocypria kraepelini, lakes by Limnocythere inopinata and I. mongolica, and running waters hosting fewer ostracods. Comparative study of the ostracod assemblages from different areas in China and Mongolia reveals intermediate to strong degree of ecological disturbance of the aquatic habitats in central-eastern Inner Mongolia, as denoted by the prevalence of the ecologically tolerant widespread species H. incongruens, L. inopinata, and P. kraepelini. We propose that the ecological disturbance of the aquatic habitats in this area originates from both artificial and natural factors: the flourishment of H. incongruens and P. kraepelini reflect unstable and polluted environments due to human activities including road constructing and livestock raising, while the ubiquity of L. inopinata is due to enriched and fluctuating water chemistry under semi-arid climate. The endemic ostracods in central-eastern Inner Mongolia show sporadic occurrence, and future conservation of these species should be focused on the sites that possess favourable ecological niches.