The results of a typological analysis of aquatic ecosystems in the Danube River Delta (the Ukrainian and Romanian parts) based on the taxonomic composition of benthic macroinvertebrate communities are given in the paper. The hierarchical clustering using the Morisita and Chekanovsky - Sorensen indices was applied to identify similarities among benthic macroinvertebrate communities in different types of water bodies. The analysis revealed distinct typologically homogeneous groups of water bodies reflecting common hydrological, geochemical, and biocenotic characteristics. An updated typology of surface water bodies and a codification of aquatic ecosystems in the lower reaches of the Danube River are proposed according to the national methodology and the requirements of the EU Water Framework Directive.
Natural water provides the normal life of animal and plant organisms. It has a fairly stable ratio of light and heavy hydrogen isotopes - protium and deuterium. When the isotopic composition of the aquatic environment changes to light or heavy water, the vital activity of animals and plants is inhibited, their metabolism is disrupted, which can lead to death. So, the biological properties of water with modified isotopic composition were considered using a set of animal and plant organisms. It has been established that both light protium water (37.5 mg/kg deuterium) and heavy deuterium water (99.9%) inhibit the vital activity of the test organisms and result in their death. The impact of light water (37.5 mg/kg) on embryogenesis of the freshwater fish resulted in decrease of the development rate and embryonal abnormalities, and in heavy water (99.9%) the fish eggs do not develop and die.
The features of the spatial distribution of phytoplankton in the cooling pond of the power plant in view of the concept of limnic continuum are discussed in the paper. It has been shown that when one or both power units of the power plant are operating and in the absence of wind, the distribution of phytoplankton occurs along radial vectors from the center of the water body to the coastline, which corresponds to the idea of a limnic continuum. In strong winds, which affect the localization of the technogenic flow and its area, the radial nature of changes in phytoplankton indices is disrupted.
The content of photosynthetic pigments in the cells of the green microalgae Tetradesmus dimorphus (Turpin) M.J. Wynne and Desmodesmus brasiliensis (Bohlin) E. Hegew was determined during the formation of their coenobia under conditions of cultivation. It has been found that in both species of microalgae the content of chlorophylls a, b, and carotenoids during the studied period of growth had tends to increase. At the same time, a significant increase in the content of photosynthetic pigments in T. dimorphus was observed at the beginning of exposure, and in D. brasiliensis - at its end. High values of the ratio of Cchl a/Cchl b and Ccar /Cchl a were noted in the studied cultures, which indicate their high functional activity. It was shown that the culture of T. dimorphus, which is characterized by a low degree of coenobia formation, had high chlorophyll a content at the initial stages of its growth, which subsequently gradually decreased. At the same time, the content of chlorophyll a in D. brasiliensis cells during the active formation of a high number of 4-celled coenobia significantly decreased, and during their disintegration - increased. The species specificity of the studied coenobial green microalgae is the predominance of unicellular forms in the growth process of T. dimorphus, and 2- and 4-celled coenobia - in D. brasiliensis.
Aquaculture is the world's fastest-expanding industry, yet faces major challenges from aquatic diseases, especially viral infections. In recent years, aquatic diseases have had massive economic and environmental consequences, and the emergence of novel aquatic infections, particularly viruses, poses a constant threat. According to recent discoveries, fishes harbour more viruses than any other vertebrate class. Fish viruses encompass a wide array of pathogens belonging to diverse viral families such as the Reoviridae, Birnaviridae, Iridoviridae, and Rhabdoviridae. These viruses infect various fish species at different developmental stages, causing diseases ranging from mild to severe, often resulting in mass mortalities and substantial economic losses. Addressing viral diseases in aquatic species remains challenging due to the scarcity of effective therapeutics available, and the discovery of potent viral vaccines for delivery in aquatic systems remains a long way off. Research efforts focusing on understanding viral pathogenesis, host-virus interactions, and vaccine development are essential for mitigating the impact of fish viruses on aquaculture sustainability. Despite these challenges, there exists limited information on the diversity, abundance, and evolution of fish viruses. This review emphasizes the diversity of fish viruses, their transmission dynamics, and their profound implications for aquaculture and prevention with a keen focus on important fish species.
The article deals with the biotechnological aspects of microalgae application in treatment of aquatic media contaminated by heavy metals, wide range of the organic micropollutants, pharmaceuticals, particularly antibiotics, pesticides, nitrogen- and phosphorus-containing compounds facilitating eutrophication. Special attention was given to analysis of the toxicants' biodegradation with microalgae participation and use of immobilized microalgae in various matrixes. The algae immobilization in matrices, along with optimization of hydraulic retention time and illumination, are identified as the key factors for enhancing purification efficiency.
The paper deals with content of phospholipids and ratio of their individual fractions in the gills, liver, and muscles of silver carp (Carassius gibelio Bloch.) and common pike (Esox lucius L.) exposed to 0.1 and 0.25 mg/dm3 of cobalt ions for 14 days. It has been shown that changes in the phospholipid profile in fish organs under the toxic impact depended on the metal concentration and were species- and tissue-specific. Thus, phospholipid profile in gills was similar in both species, whereas in liver and muscles it differed. The dynamics of the phospholipid fractions' content and the phosphatidylcholine/sphingomyelin and phosphatidylcholine/phosphatidylethanolamine ratio in pike tissues were more pronounced. Instead, crucian carp showed greater resistance to the cobalt ions, which was reflected in the efficiency of absorption and detoxification of cobalt in liver and muscles, preventing oxidative damage. The obtained data indicate remodeling of phospholipids and modulation of the cell membrane fluidity as an adaptive response to the environmental factors, in particular cobalt ions' impact.
The paper deals with the study of the influence of nutrients and their ratio on phytoplankton of the upper cascade Dnieper reservoirs. A significant positive correlation was established between nitrogen concentration and the quantitative indices of phytoplankton development. A polynomial relationship was established between inorganic phosphorus concentration and phytoplankton biomass. At phosphorus concentration below the threshold value of 0.05 mg/L, which corresponds to the Redfield ratio (16N: 1 P), there is a significant positive correlation between Pinorg and phytoplankton biomass, and at its concentration above 0.05 mg/L, no significant correlation was registered. It has been found that the highest phytoplankton species richness, numbers, and biomass were observed at nitrogen and phosphorus ratio in the range of 11-30. It has been proven that in the mesotrophic-eutrophic ecosystems of the Kyiv and Kaniv reservoirs, the Vollenweider law does not work, since at present, unlike the 1960s-1980s, phosphorus is not a limiting factor for phytoplankton vegetation.
The paper is dealt with the study of the diversity of macrophytes in Lake Bile and assessment of changes over the past 25 years. Significant qualitative and quantitative transformations in the structure of plant communities were observed in the areas subject to recreational use. It has been found that the share of eutrophication-tolerant species in the macrophyte flora of the lake is increasing, while the number and cenotic role of taxa sensitive to the disturbance of natural conditions are decreasing. The results highlight the need for conservation measures to preserve the ecosystem of Lake Bile.
Information on the species composition and quantitative indices of macrozoobenthos communities in the Gorikhuvatka ponds (the Golosiyivsky National Nature Park, Kyiv city) is presented. Species diversity (Shannon's index) and species composition similarity (Sorensen's index) of benthic fauna in different ponds and sections of the Gorikhuvatka River connecting them were established. Ecological characteristics, including saprobity and trophic level, and also the classes and categories of water quality, were calculated in the studied ponds in terms of macrozoobenthos indices. Cluster and comparative analyses of macrozoobenthos abundance, biomass, species number, and its species composition were performed. The signs of discreteness and continuity of different ponds and the pond system as a whole were revealed in terms of benthic fauna indices.
The article deals with feeding habits of four goby species (Neogobius melanostomus, Ponticola cephalargoides, Ponticola ratan, Ponticola eurycephalus) in the Odesa Bay over summer 2020. In the study, 276 stomach contents and 29 macrozoobenthos samples collected along the coastal zone of the Odesa Bay were analyzed. The results showed that P. eurycephalus and P. cephalargoides have similar diet (similarity index 67.9%), they consumes mainly crustaceans (Carcinus aestuarii), N. melanostomus specializes in mollusks (Mytilaster lineatus, IFS = 6668.7%), and P. ratan prefers oligochaetes (IFS = 2597.1%). The Horn's index (0.9 for P. eurycephalus and P. cephalargoides) suggests potential competition. Findings highlight the trophic flexibility and adaptability of these species to the environmental conditions of the Odesa Bay.
Some physiological and biochemical parameters of rudd (Scardinius erythrophthalmus L.) and perch (Perca fluviatilis L.) from the water bodies of the Chernobyl Exclusion Zone (CEZ) were studied within the absorbed dose rates range of 5.1-18.7 μGy/h. It was found that the specimens from CEZ water bodies were characterized by higher fattening and increased liver index compared to the control (0.06 μGy/h), which indicated activation of the compensatory mechanisms aimed at mitigation of the negative environmental impact. This was confirmed by the reduced RNA content and RNA/DNA ratio in gills of these specimens, indicating inhibition of the biosynthetic processes in tissues, primarily protein synthesis. In liver of specimens from CEZ, content of lipid peroxidation products (diene conjugates and malondialdehyde) was elevated, indicating the cell membranes damage owing to the free radicals' impact and development of oxidative stress, which can lead to pathological processes in the organism.
The aim of the study was to investigate the totality of local benthic macroinvertebrate communities in the Kilia arm of the Danube Delta from positions of the metacommunity theory, with a focus on identification of the core environmental drivers and species groups that determine the formation and maintenance of its spatial structure. The application of the pattern-based Elements of Metacommunity Structure (EMS) approach enabled to establish that metacommunity of the benthic invertebrates in the Kilia Delta corresponds to the quasi-Clementsian structure, consisting of distinct species' groups associated with brackish water bodies, fresh water bodies, and fresh water courses, with blurred or absent transition zone between them. This structure is maintained by distribution patterns of 27 peculiar species, which provide connections of the individual localities both within and across the identified water bodies' groups. Effects of salinity and the flow intensity on distribution of these peculiar species, along with spatial distance between the local communities resulted in prevailing of the species sorting mechanisms along the environmental gradients within this metacommunity.
The paper deals with microbiological and hydrochemical studies of the Kyiv section of the Kaniv Reservoir over 2022-2024. The abundance of bacterioplankton ranged from 3.9 to 14.9·106 cells/cm3, portion of bacteria with damaged cytoplasmic membranes was 10.5-87.5% of the total numbers. The abundance of eutrophic and oligotrophic bacteria amounted to 30.0-475.8·103 and 2.1-226.7·103 cells/cm3, respectively. The studied microbiological and hydrochemical parameters were characterized in seasonal, spatial, and interannual aspects. Seasonal fluctuations in bacterioplankton development depended on temperature regime, water level, dissolved organic matter quality, and anthropogenic pressure, including that caused by hostilities. Certain elements of the hydrological regime, hydrochemical, and microbiological parameters significantly correlated (p ≤ 0.03). In the spatial distribution, similar fluctuations of the average abundance of bacterial communities was observed in the bays and river section; however, the ranges of fluctuations differed being broader in the bays. Interannual changes of the bacterial abundance in water were comparable, except for the dead bacteria portion, which gradually decreased about 1.5 times during 2022-2024. The abundance of the sanitary indicatory bacteria and opportunistic microorganisms indicated that the water quality of the Kyiv section of the Kaniv Reservoir did not meet the sanitary-ecological safety standards at all studied sites. According to the ecological classification of the surface water quality based on the abundance of eutrophic bacteria, the Kyiv section of the Kaniv Reservoir was classified as "very bad" corresponding to the V quality class. The observed changes in ammonium nitrogen, phosphate phosphorus concentrations, and organic matter content (in terms of CODMn and CODCr) resulted from the intensified impact of natural and anthropogenic factors, as well as unstable operational regime of the Kyiv hydroelectric power plant.
It has been shown that the macroscopic green filamentous algae Spirogyra sp. and Oedogonium sp. from the ponds of the Golosiyivsky National Nature Park (Ukraine) accumulate and concentrate a significant amount of heavy metals (Fe, Mn, Zn, Cu, Ni, Cr, Pb, Co) from the aquatic environment, leading to its purification and detoxification. The established values of the bioaccumulation factors of metals by algae ranged from hundreds and thousands (for Zn, Co, Cr, Cu, Ni, Pb) to tens of thousands (for Fe and Mn). According to the values of bioaccumulation factors in algae, the studied metals are arranged in the following order: Fe > Mn > Zn > Ni, Co > Cu, Pb, Cr. A significant correlation between the content of heavy metals in the green filamentous algae Spirogyra sp. and Oedogonium sp. and the concentration of soluble form of metals in the water of the ponds of the Golosiyivsky National Nature Park has been established. This fact makes it possible to recommend these species for use as biomonitors of heavy metal pollution of water bodies.
The paper deals with the processes of Typha angustifolia L. colonization by algae in the river section of the Kaniv Reservoir. At the end of the first week of exposure, the free surface of study plants was colonized by algae (primary colonization), the species richness of the newly formed community comprised 79 species and infraspecific taxa, and the biomass reached 0.192 mg/10 cm2. In the third week of exposure, phytoepiphyton biomass on study plants decreased significantly, however in the fourth week "recolonization" of the free patches took place. It has been shown that the daily flow velocity and water level fluctuations directly affect the processes of colonization. When water level is high and its fluctuations are insignificant, phytoplankton and phytoepiphyton on neighbor plants are the main sources of species immigration to phytoepiphyton on study plants, and when water level drops down abruptly, species mainly immigrate from microphytobenthos. The migration of typically plankton Aulacoseira italica to the surface of plant substrates can be considered as mass effect. A significant positive correlation was established between A. italica biomass in phytoepiphyton on study plants and its biomass in phytoplankton (r = 0.97, p = 0.007). No such correlation has been found for phytoepiphyton on background plants, because their phytoepiphyton communities had been forming for a longer time, with species sorting processes prevailing.
The accident discharge of wastes from the sugar factory in the russian town of Tiotkino in September 2024 resulted in heavy pollution of the Seym River and unprecedented fish kill caused mainly by the oxygen deficit. Among the dead fishes rheophiles prevailed - specimens of four species formed 73.3 %, specimens of the adventive crucian carp counted for 12.9 %, and specimens of seven limnophilous species counted for 13.7 %. Analysis of catches of juvenile fishes in October 2024 in the same sites as in 2021 showed principal modification of ichthyocenosis of the riverbed: change of the dominant species, species number in the catches decreased from 20 to 12, species diversity in terms of the Shannon index decreased 1.4 times. Total juveniles' numbers in the catches decreased 7 times, limnophilous 5.9 times, rheophilous 38.9 times, adventive 39 times, species of the Red Data Book of Ukraine 9 times. At the same time, species number and numbers in the catches in the flood-land lakes increased. The common loach Cobitis taenia s. l. was the only species that did not decrease numbers, at this ratio of its diploid and polyploid forms did not change after the disaster. According to assessment of the State fishery agency, total mass of dead fishes amounted to 40.3 t, this 2-8 times exceeded commercial catches in the Desna River basin before the hostilities. Considering changes of the hydrological regime over the last decade, the ichthyocenosis rehabilitation will take some years, successfully at the expense of the limnophilous and adventive ichthyofauna only.
The effect of exogenous phytohormones on the accumulation of biomass of the aquatic floating fern Salvinia natans (L.) All., as well as the content of endogenous phytohormones of the cytokinin class during the period of intensive and stationary growth, was studied. It has been found that the effect of adding growth-regulating substances to the plant cultivation medium depended on their concentration and growth stage, and probably on the balance of endogenous phytohormones. Kinetin and abscisic acid (ABA) had opposite effects on fern biomass accumulation, and the direction of this effect also varied depending on the intensity of growth processes. The regularities of the effect of these phytohormones at different stages of growth are discussed in connection with the dynamics of endogenous cytokinins and ABA in sporophytes. Cytokinin hormones can be considered as a factor in increasing the productivity of S. natans during the period of slowing down of growth processes, which is important for the development of modern methods of phytoremediation of anthropogenically polluted water bodies.
The study of the effect of 19 biocoordination compounds of germanium (IV) and four compounds of stannum (IV) on activity of elastase of Bacillus licheniformis IMB B-8008, isolated from the bottom sediments of the Black Sea, showed that they have a multivector effect. Maximal stimulating effect was exhibited by [M(H2O)6][Ge2(OH)2(H2Glu)2]·nH2O (H6Glu is gluconic acid, M = Cu), which stimulated the elastase activity by 65%, whereas [Fe(phen)3]4[Ge6(μ-OH)4(μ-O)2(μ-hedp)6]·20H2O and [Fe(phen)3]2[{Sn(HMal)2(Mal)}Cl]·14H2O showed maximal inhibiting effect (100%). The inhibiting effect of these compounds did not depend on their concentrations and incubation time. The stimulating effect of [M(H2O)6][Ge2(OH)2(H2Glu)2]·nH2O (H6Glu is gluconic acid, M = Cu) was manifested only under its concentration of 0.1 %, whereas under 0.01 % it did not show any effect. The results obtained are important for the inhibition of the elastase activity of pathogenic microorganisms occurring in the seas and oceans.
The paper deals with seasonal fluctuations of the main microbiological indicators in samples of the freshwater fishes (common carp and round goby) from the Khadzhybey estuary. Attention was focused on use of live fishes as bioindicator of pollution of the aquatic environment, as sanitary condition of the reservoir is unsatisfactory. Besides, high microbial pollution of the reservoir can pose a threat to public health. It was found that during 2021-2022, the values of total bacterial contamination in fish samples were almost constant throughout the year, with a clear tendency to increase in summer, with a gradual decrease in the autumn-winter period due to self-purification processes in the reservoir. In 2023, a significant increase in parameters was detected in summer (June), which coincided with catastrophe of the Kakhovka HPS, but then total bacterial contamination stabilized. No Escherichia coli was detected in any sample, indicating the absence of fecal contamination of water in the Khadzhybey estuary and satisfactory operation of water treatment facilities. The results demonstrate that over periods of increased water temperature, special attention should be paid to conducting veterinary and sanitary inspection of fresh fish, as it can become a source of food-borne infections and toxicoinfections.
