Intense “blooming” of cyanobacteria (blue-green algae) caused by eutrophication and climate change poses a serious threat to freshwater ecosystems and drinking water safety. Preventing the proliferation of cyanobacteria and reducing water nutrient load is a priority for the restoration of eutrophic water bodies. Aquatic plants play an important role in the function and structure of aquatic ecosystems, affecting the physiochemistry of the water and bottom sediments, primary production, and biotic interactions that support a balanced ecosystem. This review examines the inhibitory effect of aquatic vascular plants on harmful blooms of cyanobacteria. Aquatic plants are able to successfully inhibit the growth of cyanobacteria through various mechanisms, including by reducing nutrient and light availability, creating favorable conditions for the development of herbivorous zooplankton, and releasing allelopathic active substances (allelochemicals) with algicidal effect. Allelopathy is species-specific and therefore acts as one of the key mechanisms by which the development of cyanobacterial populations in aquatic ecosystems is regulated. However, allelopathic activity of aquatic vascular plants depends on various factors (species characteristics of aquatic plants, area, and density of overgrowth of water bodies, physiochemical properties of allelopathically active substances, hydrological and hydrochemical regimes, temperature, light intensity, etc.), which may regulate the impact of allelochemicals on algal communities. The paper also discusses some problematic aspects of using fast-growing species of aquatic vascular plants to control cyanobacterial blooms.

The qualitative and quantitative composition of phenolcarbonic acids in phytomass of higher aquatic plants of different ecological groups (Scirpus lacustris, Ceratophyllum demersum, Potamogeton perfoliatus and Nuphar lutea) was analyzed by the HPLC/MS method. Analysis of the phenolcarbonic acids content in plants using clustering by the Pearson's correlation coefficient is presented. Hypothetical scheme of flavonoids forming over phenolcarbonic acids biosynthesis in macrophytes has been proposed.

At cultivation of Chlorella vulgaris Beijer. culture (strains LARG-3, HPDP-120) in close system at medium saturation by CO2 it was stated that at initial stages extra carbon dioxide negatively affected functional activity and caused changes of morphological characteristics of the alga. However this phenomenon vanished in course of adaptation to the given conditions, it was reversible at reduction of the CO2 content in the system.

It was shown that the optimal substrates for growth and development of the non-biting midges Chironomus riparius larvae are silty and fine sandy. The larvae are able to select the substrate; they prefer fine fractions and avoid larger-medium sand fraction, but substrate preference of larvae is determined rather by food conditions than particle size.