Features of Zoobenthos of Mesohumus Lakes of the Republic of Karelia in a Natural State

Abstract

The results of studies of the current state of zoobenthic communities of lakes Sukkozero and Gimolskoye, located in the western part of the Republic of Karelia (Muezersky district), are presented. Under conditions of high color and low mineralization of waters, communities are formed with a predominance of chironomid larvae, caddisflies, mayflies, and oligochaetes. Biomass and abundance indicators in 2017–2018 were within 0.41–0.75 g/m2 and 315–685 ind./m2 in the lake Sukkozero and 0.41–0.93 g/m2 and 220–346 ind./m2 in the lake Gimolskoye. The highest values of abundance and biomass were noted in biotopes of silty soils (overgrown littoral and profundal), the lowest values in the biotope of sandy littoral. According to the level of quantitative development of zoobenthos, Sukkozero belongs to oligotrophic water bodies; Gimolskoye – mesotrophic. The experience of using common biotic indices for assessing the ecological quality of waters (Mayer, oligochaete, saprobity, chironomid) indicates that low mineralization and high humus content can affect their performance and distort the assessment of real organic pollution.