THE ECOLOGICAL ASSESSMENT OF THE SMALL RIVER ECOSYSTEMS STATE ACCORDING TO BIOLOGICAL DIVERSITY OF PHYTOPLANKTON AND PRODUCTION CHARACTERISTICS OF ALGAE

This paper presents the results of inventory of autotrophic components of small rivers of the Central Polesye with different levels of human activity - Kroshenka (Zhytomyr) and Kodnyanka (settlement Pryazhiv Zhytomyr district). Patterns of primary production and decomposition of organic matter in streams have been studied, quality of the aquatic environment of small rivers according to saprobiological characteristics of indicator species of algae has been assessed. The aim of the study was to evaluate the current status of small rivers of the Central Polesye (with varying degrees of anthropogenic load) according to the diversity of phytoplankton. Algological samples were conserved, concentrated and worked on a desk by generally accepted methods in hydrobiology. The paper used taxonomic system of algae proposed in the latest reference book «Algae of Ukraine». Biological indication analysis has been made on the basis of indicator properties of algae. Phytoplankton primary production and organic matter decomposition was measured by oxygen modification of light-and-dark-bottle method. Hydrochemical, floral comparative and statistical methods being used allowed to identify the factors determining the patterns of phytoplankton formation and functioning in the rivers under research. During our research 206 species of algae were found in the river plankton, represented by 209 infraspecific taxa, including those containing nomenclatural species type. According to its species composition, phytoplankton of the rivers under research can be described as Chlorophyta-Bacillariophyta-Euglenophyta. According to biological indication characteristics, benthic and plankton forms of algae, indifferent in relation to pH and salinity degree, indicators of average flow of water and moderate temperature regime, mildly alkaline waters dominated the water column. A leading role of β-mezosaprobionts was found. The river water according to the level of organic contamination pursuant to Pantle-Buck method (modification of Sladechek) belongs to class III of quality (water "satisfactory quality"), and according to the system of Watanabe it is characterized as water with moderate content of organic compounds. The rivers Kodnyanka and Kroshenka are distinguished by high productivity. Positive balance of organic matter predominates, which indicates the autotrophic direction of ecosystems' metabolism. However, significant predominance of production processes above destruction was recorded in r. Kroshenka and this can lead to accumulation of excessive amounts of organic matter. Succession of river ecosystems takes place under condition of natural factors predominating at the present stage of their functioning. Disturbance of the natural succession in the river Kroshenka is caused by anthropogenic impact of Zhytomyr and reduces the informational diversity and balance of production-destruction processes