loading . . . Species Structure of Communities of Oligochaetes (Oligochaeta and Annelida) in the Upstream Water of the Pechora and Vychegda Rivers: A Comparative Faunal Analysis - Inland Water Biology Abstract Oligochaete communities of different landscapes in the upper reaches of two large rivers flowing through the European northeast of Russia—Pechora and Vychegda—are compared. A high diversity of oligochaetes (42 taxa) is found, with species common to both rivers comprising only 26% of the fauna. The family Naididae prevails in species richness in both rivers. Dominant species include Lumbriculus variegatus, Nais communis, and Propappus volki in the Pechora River and Nais bretscheri, Stylodrilus heringianus, Spirosperma ferox, Limnodrilus hoffmeisteri, and Potamothrix hammoniensis in the Vychegda River. It is shown that the diversity in the studied parts of the rivers is primarily based on a large number of rarely encountered species. Calculations of diversity indices reveal opposite trends for the oligochaete communities in the upper reaches of the Pechora and Vychegda rivers. For the Pechora River, an increase in alpha diversity, expressed by the Shannon (HN) and Simpson (1-DS) indices and species richness, is observed from the upper (mountainous) to the lower (plains) section. Conversely, for the Vychegda River, a decrease in diversity downstream is noted. The comparison of faunas between the rivers (beta diversity), expressed by the Whittaker index, shows higher diversity of oligochaete communities in the upper reaches of the Pechora River. https://doi.org/10.1134/s1995082925600437
