Community Structure of Oligochaetes (Annelida: Oligochaeta) of the Vychegda River in the Zone of Influence of Wastewater from Pulp and Paper Production

This paper contains original data on the composition and structure of Oligochaeta communities in the zone of influence of wastewater from a pulp and paper mill (the Vychegda River, Northern Dvina River basin). Forty species and forms of oligochaetes have been identified. We have found species which had been earlier identified only in tributary floodplain water bodies and lakes of the Vychegda River basin. According to the diversity index (Shannon index (H_N) and Simpson index (D_S)), evenness index (Pielow index (E)), and Whittaker (βw) indices, the studied section of the river exceeds the control section in regards to species diversity. There is a significant increase in abundance and biomass of oligochaetes in comparison to the section upstream the river. Based on a correlation analysis between the quantitative development indicators of oligochaetes and the environmental parameters (type of substrate, presence of algal growths and macrophytes, depth, and chemical composition), an assessment of biotopic confinement of species (F_j), and the conjugate between species (r_A), we found that the distribution of oligochaetes in the study area largely depends on the type of substrate. According to the results of the assessment of diversity and distribution of oligochaetes in the zone of influence of wastewater from a pulp and paper mill, the appearance of technogenic areas with an artificial substrate along the bank line leads to changes in the composition, diversity, and quantitative development characteristics of benthic organisms.