Development of a Multimetric Index Based on the Composition and Structure of Macrozoobenthos for Assessing the Ecological Status of Altai Low-Mountain Lakes

Multimetric indices (MMIs) are an important biomonitoring tool that is widely used to assess the ecological status of aquatic ecosystems worldwide. The effectiveness of MMIs lies in their ability to combine both the structural and functional features of communities of organisms, as well as the features of the entire ecosystem. The use of organisms such as macroinvertebrates in the development of MMIs is most common in lake biomonitoring. No such work has been carried out in Russia to assess the ecological state of lakes. In this study, an MMI based on the composition and structure of macroinvertebrate communities is developed for low-altitude Altai lakes experiencing high recreational and agricultural stress. The lakes are put into two groups according to the degree of organic pollution: reference and disturbed. Using a step-by-step statistical analysis, five metrics were selected from 55 indicators of macrozoobenthos communities, which were included in the final MMI. The selection tests included sensitivity (discrimination), stability (seasonality), redundancy, and correlation with environmental variables (abiotic factors). The new index is compiled by the following metrics: Pielou’s evenness index, the number of mayflies species, the occurrence of shredders, and the abundance of caddisflies and gammarids. These indicators are evaluated on a continuous scale and divided into six classes of water quality in accordance with the classification adopted in Russia. The index demonstrated the ability to distinguish not only dirty and clean lakes, but also moderately polluted water bodies. The new index can become an informative tool for monitoring and assessing the ecological status of lakes.