МІКРОФІТОБЕНТОС ЯК БІОІНДИКАТОР ЗМІНИ ГІДРОМОРФОМЕТРИЧНИХ ПАРАМЕТРІВ ВОДНОГО ОБ’ЄКТУ МІСТА КИЄВА

A great number of water bodies within urban areas of Kyiv City are exposed to human impact. Hydrotechnical construction operations alter their morphometric and hydrological parameters, water bodies are contaminated with various inorganic and organic substances etc. Since human impact upon water bodies has diversified, bioindication is a well-established and effective method of assessing water bodies’ ecological status and measuring the rate of their ecosystems’ disturbance. Microphytobenthos is an important element of aquatic ecosystems and is widely used as a reliable biological indicator. While using microphytobenthos as an ecological community, it is required to evaluate the bioindication efficiency of its indicative structural elements, which respond distinctly to changes in anthropogenic factors on the whole and in the degree of human impact upon water bodies of different types. This paper considers the findings of studying microphytobenthos indicative structural element bioindication characteristics – ecological-morphological group of benthic filamentous blue-green algae and their role in forming the respective parameters among benthonts in the littoral area of Opechen Lower Lake, located within Kyiv City residential community. Large-scale hydrotechnical construction operations conducted in the lake in 2019 greatly affected its hydromorphometric parameters by reducing the shallow-water area and disturbing the bottom sediments stability, which resulted in increase of the human load. The objective of the study was to identify key characteristics of the microphytobenthos indicative structural element under conditions of the lake’s hydromorphometric parameters alteration. Benthic algae were sampled with the MB-TE microbenthometer within the littoral area at aquatic-vegetation-free sites located in the lake’s upper and lower sections. Algae sampling and laboratory processing of samples were performed in accordance with the methods generally accepted in hydrobiology. For diatoms identification permanent slides were made with using special high-resolution mounting media. Autochthonous components in microphytobenthos, the indicative ecological-morphological group of benthic filamentous blue-green algae were distinguished proceeding from algae’s association with particular biotopes. In addition to separate characteristics (species richness, number, biomass), a multimetric index was calculated for the benthonts’ indicative group as an arithmetic average of several characteristics. The degree of human impact upon the lake ecosystem was calculated according to the proven method, consisting in distinguishing the total number of the most obvious human factors with consideration taken of their different intensity. The findings of studying the key characteristics of phytomicrobenthos indicative structural element – benthic filamentous blue-green algae in 2018–2019 confirm their high bioindication efficiency and distinct response to hydromorphometric parameters alteration in Opechen Lower Lake. As a consequence of hydromorphometric alterations the share of these algae in the benthonts’ species richness, number and biomass has decreased by half, and the vegetation-period-average multimetric index has lowered by 1.7. This gives the evidence that the conditions for bottom algae vegetation have worsened.