Assessment of the ecological status of the river water system in European North under conditions of ultra-fresh humus waters using biotic indices (Suna River, Lake Onega Basin, Russia)

Abstract

An assessment of the ecological state of the lake–river system of Eastern Fennoscandia in the European North of Russia has been carried out. It was found that in conditions of ultra-fresh waters with a high humus content, biotic indicators may indicate pollution of water bodies that do not actually experience significant anthropogenic impacts. Based on the indicators of macrozoobenthos and phytoperiphyton (indices such as FBI, EBI, BMVP, ASPT, BBI, IBGN, SI, GV, EPT, IB, IM, and TDI), a comprehensive assessment of water quality was given. Ratings ranging from ‘poor’ to ‘excellent’ were obtained for different stations, reflecting the influence of natural features of different sections of the river. ‘Good’ water quality was noted at the river rapids. For river reaches and lake biotopes, ‘mediocre’ water quality was revealed. The low anthropogenic load on the river catchment allows us to conclude that most indices for assessing water quality significantly underestimate the results in the natural conditions of Eastern Fennoscandia. The relatively poor natural fauna, low water salinity and high humus content can make it difficult to determine the level of anthropogenic pollution using biotic indicators. The most error-prone indices are GW and IBGN, of which the former overestimates and the latter underestimates.