Active producers were selected as a result of studies on the ability of exoproteases of supernatants of culture liquids of bacteria isolated from bottom sediments of the Black Sea to hydrolyze fibrin, fibrinogen, and collagen. It was shown that partially purified enzyme preparations of <i>Bacillus subtilis</i> 248 and <i>Bacillus subtilis</i> 231 differed in physicochemical properties. Thus, the fibrin-(ogen)olytic activity of <i>B. subtilis</i> 248 has a pH optimum of 9.0, and the thermooptimum of fibrinogenolytic activity is 4-20 °C, while that of fibrinolytic activity is 15-20 °C. The partially purified enzyme preparation <i>B. subtilis</i> 231 has two pH optimums of fibrin(ogen)olytic activity - 7.0 and 11.0, and the thermooptimum - 37 °C. It was established that <i>Bacillus subtilis</i> 248 and <i>Bacillus subtilis</i> 231 may be promising for further scientific research as producers of proteases with α/β/γ-fibrinogenase and α/β-fibrinase activity.

Sulfated polysaccharides (SPs) from algae have been shown to be effective in a number of biological applications. Therefore, the chemical composition and different biological functions of various SPs were determined for three brown seaweed species from the Egyptian Red Sea: <i>Dictyopteris polypodioides, Polycladia myrica</i>, and <i>Turbinaria decurrens</i>. It has been found that the yield of crude SPs was higher than that of alginate and fucoidan with a range of 43.64% to 61.90%. Fucoidan, which has the maximum carbohydrate content of 56.89%, was found in <i>D. polypodioides.</i> The crude SPs of <i>P. myrica </i>had the greatest sulfate content of 22.44%. All functional groups of the examined samples were confirmed by the Fourier Transform Infrared spectrum (FTIR). Experimentally, three applicable assays were used to quantify the antioxidant activity of the extracted SPs depending on the method used, the type of polysaccharides, and algal species. The anti-diabetic activity of <i>T. decurrens</i>-crude SPs was highly active scoring 85.85% in the α-glucosidase assay. The anti-obesity activity showed the highest value (95.25%) for <i>T. decurrens</i>-fucoidan. Besides, <i>T. decurrens</i>-crude SPs showed the highest anti-arthritic activity (89.89%). In addition, a few positive records of antibacterial activity were detected. Furthermore, the most potent <i>T. decurrens</i>-crude SPs extract was tested for cytotoxicity against human liver cells and found to be safe. The activity of the isolated SPs and their chemical composition were shown to be correlated. Conclusively, the bioactivities recorded herein by the tested SPs pose promising medicinal applications towards developing a new therapeutic intervention.

The article deals with influence of heavy metal ions (cadmium, zinc, copper, lead, chromium, manganese and nickel) on β-carotene content in hemolymph, hepatopancreas, mantle and foot of <i>Lymnaea stagnalis</i>. Its content dynamics was non-linear, owing to nature and specificity of the ions' effects, the exposure time and metabolic features of the organs and tissues. Over the two-day exposure, the impact Cr<sup>3+</sup>, Mn<sup>2+</sup>, Cu<sup>2+</sup>, Ni<sup>2+</sup> and Cd<sup>2+</sup> ions resulted in increase of β-carotene content in the <i>L. stagnalis'</i> hemolymph, indicating development of the immediate response to the toxic effects aimed at homeostasis. The Cr<sup>3+</sup> impact caused its growth in hepatopancreas, mantle, and foot. The β-carotene content dynamics under the impact of all studied ions was organ-specific. Over the fourteen-day exposure, the suppressive effect of Mn<sup>2+</sup>, Cu<sup>2+</sup>, Ni<sup>2+</sup>, Cd<sup>2+</sup>, Cr<sup>3+</sup> and Zn<sup>2+</sup> on the <i>L. stagnalis</i> metabolism increased, expressed in decrease of β-carotene content by 12.2-66.9%, except in hemolymph where under the impact of Cr<sup>3+</sup> it increased 3.2 times, and in foot where under the impact of Ni<sup>2+</sup> it remained at the control level. The hierarchical cluster analysis enabled to reveal regularities of HM ions impact on β-carotene content in hemolymph, hepatopancreas, mantle and foot of <i>L. stagnalis</i>.

Microphytobenthos of water bodies of some Maldivian Islands (Kelaa and Filladho) and the Madagascar Island of the Indian Ocean was studied in autumn (September and November) 1981. As a result of the performed investigations, 43 species of microscopic algae belonging to 30 genera, 25 families, 21 orders, 5 classes, 3 divisions, 2 kingdoms, and 2 empires (domains) were found. Among them, diatoms (38 species) prevailed over Dinoflagellata (4) and Cyanobacteria (1). The Sorensen - Chekanovsky coefficient of community similarity between the Maldivian and Madagascar floras was 0.56 and the Jaccard coefficient of community similarity was 0.36. Microphytobenthos of the investigated water bodies was of marine type. It was represented by alkaliphilous species and cosmopolitan (27 species) and tropical (10) groups with boreal-tropical (4) and boreal-tropical-notal (2) elements.

The paper deals with comparative analysis of the main abiotic factors and phytoplankton taxonomic characteristics in various ecosystems of the Dnieper River, including the head cascade Kyiv Reservoir and the natural Dnieper estuary. Investigations were carried out in summer seasons of 2014-2020. The studied water bodies differ significantly in their physical, geographic, climatic, hydrological, and hydrochemical characteristics. However, they have some common features: both water bodies are large highly productive lentic ecosystems with similar morphometric parameters. As regards phytoplankton taxonomic diversity, the similarities include the same rank distribution of leading divisions and high species richness of summer phytoplankton. A number of differences has also been observed: a higher share of Bacillariophyta in the reservoir and higher shares of Cyanobacteria and Miozoa in the estuary; higher species richness of phytoplankton in the Dnieper estuary compared to the Kyiv Reservoir; a large number of species, occurring only in one of the studied ecosystems - 75 species in the Kyiv Reservoir and 88 species in the Dnieper estuary. The obtained data can serve as a background for assessing an adverse effect of the Russia's military aggression and arising hazards for the Dnieper ecosystems of Ukraine.

The paper deals with the structural features of the waterbirds' cenoses, the fish population composition and distribution of metacercariae of trematodes, whose final hosts are waterbirds, in the model shallow lentic ecosystems of the city of Kyiv (Almazne, Martyshev, Verbne lakes and Sovski ponds). The waterbird cenosis was dominated by ichthyophagous (58.5-75.7%) and pantophagous birds (16.4-41.42%). The black-headed gull <i>Chroicocephalus ridibundus</i> (21.9-56.7%) prevailed in terms of relative abundance everywhere. The ornithocenoses differed in terms of the subdominant species: in the Almazne lake it was <i>Podiceps cristatus</i>, in the Martyshev Lake - <i>Sterna hirundo </i>(14.6%), in the Sovski ponds and Verbne Lake - <i>Anas platyrhynchos</i> (12.8-20.2%). Differences in the coastal ornithocenoses' composition were confirmed by results of the cluster analysis WPGMA (weighted pair-group centroid (median)); distance measure - 1-Pearson <i>r</i>). The coastal fish population comprised 24 species, including the native fresh-water (15 species), Ponto-Caspian and Mediterranean self-dispersers (4 species), and alien species - distant invaders (5 species). Parasitological studies revealed trematode metacercariae localized in lens (<i>Diplostomum</i> sp.) and vitreous body (<i>Tylodelphys clavata</i>) of the eye, ripples (<i>Apatemon gracilis</i>), and in the integument of the body (<i>Posthodiplostomum cuticola</i>). The discriminant analysis enabled to reveal significant differences in the species composition and abundance of trematode metacercariae in the water bodies with different structure of the water ornithocenoses (Wilks' Lambda: approx. 0.92235; <i>F</i>(8, 510) = 2.6293f) - 2.6293; the dispersion analysis showed confidently lower total number of trematode metacercariae in the Almazne Lake (Wilks' Lambda = 0.87377; <i>F</i>(6, 432) = 5.0253; <i>p</i><0.00005).

The levels of contamination of the water bodies of the "Oleksandriya" arboretum (the town of Bila Tserkva, Ukraine) by heavy metals, petroleum products, and anionic synthetic surfactants were investigated in August 2022 and their potential toxicity for aquatic organisms was assessed. It has been proven that the detected concentrations of some heavy metals (Cu, Zn, Mn, Fe, and Pb) in the ponds located in the Western ravine of the "Oleksandriya" arboretum can exert an adverse effect on the vital activity of hydrobionts (aquatic plants, fish, etc.). The maximum concentration of petroleum products was registered in the water of the Kholodny pond (the Eastern ravine of the park), which can cause toxic effects in hydrobionts. The water of the ponds also contained anionic synthetic surfactants probably due to the influx of municipal sewage, which also results in worsening the ecological and toxicological state of the studied water bodies.

The hydrochemical parameters, the production and destruction of organic substances in different areas on the Ros and Protoka rivers were studied. Nearby the Horodyshche vil. (Ros River) and Pishchana vil. (Protoka River), concentration of ammonium nitrogen exceeded control values 2-5 times, nitrites - 1.5-2.5 times, nitrates - almost 3.0-5.8 times (as control the Ros River in the Olexandria dendrological park was used). Water of the considered sections was significantly contaminated by pesticides (chlorpyriphos) from the adjacent territories. Elevated content of nutrients in water conditioned intensive production processes (Pishchana vil.), whereas high chlorpyriphos content (Gorodyshche vil.) along with significant concentration of chlorpyriphos (Gorodyshche vil.) suppressed organic matters' production. The water quality deterioration and presence of the toxic contamination caused decrease of the size-mass parameters of common ruff, river perch and common rudd, mainly owing to decrease of somatotropin content in blood. The gonadosomatic index of perch and rudd females from contaminated water bodies increased, whereas in males it decreased as compared with the control. The relative and absolute fertility of rudd increased along with increase of the contamination degree. The females' fertility growth under the unfavorable conditions was associated with increase of the estradiol content in blood. The perch and rudd males were characterized by decrease of the gonadosomatic index along with decrease of the testosterone content in blood. Decrease of size and mass parameters and increase of the females' fertility is an adaptive response aimed at the population maintaining and higher vitality under toxic environment. These processes are provided by hormonal regulation of metabolic processes.

Based on analysis of the archive, literature and cartographic data and results of the field surveys in 2023-2024, distribution of the water bodies (WB in terms of EC WFD) was established. The ratio was established between the linear and polygonalWBincluding natural and candidates to the heavily modified. The WB distribution was assessed according to the significant changes of the certain descriptors. They included catchment area, length, water surface area and depths (for polygonal WB), as well as WB distribution owing to the main modifying factor (regularity degree and morphological modifications), and assessment of the risk of not-achieving the ecological objectives. The peculiarities of the water regime of the studied rivers within individual WB, the flow-influencing factors, decrease in the minimum flow rate, and changes in morphological features were analyzed. The crucial role of the Irpin drainage system in the anthropogenic transformation of the rivers of the basin and specific conditions in the estuary of the Irpin River supported by the Kyiv Reservoir were considered. The main hydrological and morphological effects of hostilities in the basin (flooding of the Irpin River estuary, destruction of hydraulic constructions and bridges) were assessed. It is proposed to partially adjust the boundaries of the delineated WBs and delineate additional WB due to changes in the basin under the hostilities impact.