No 6 (2023)

The hydro-chemical data collected today and structural and quantitative parameters of phyto- and zooplankton from Maloe More Strait, Lake Baikal, were analysed. Comparison of current and earlier observations revealed recent alterations in phyto- and zooplankton functions analogous to other areas of Lake Baikal. Major reconstructions in phytoplankton were registered in spring: violation in cycles of annual growth maxima of large-cell Baikalian diatoms and changes in dominant species. Dramatic abundance of rotifers caused the increase by an order of magnitude in pelagic zooplankton numbers in 2019–2020. In 2021, all of these groups were suppressed under intensive diatom vegetation. In the Mukhor bay, such changes were related to a sharp increase of rotifer numbers until 2021. In 2021, we observed decline in plankton abundance, meanwhile the relative proportion of taxonomic groups did not change with dominance of rotifers.

The study was conducted in the river section of the Gorky reservoir in the zone affected by the heated water discharge from the Kostroma hydroelectric power plant during the growing season (May–November) 2021. The reduced species richness was observed in the sites of the maximum water heating, which, however, quickly returned to the initial values in the downstream section of the river. The lethal effect of warm waters on zooplankton is mainly manifested in the summer, when the natural warming of the river waters is influenced by the heated water discharge from the Kostroma hydroelectric power plant. In autumn, the warming effect of heated waters, on the contrary, promotes better survival of organisms. Fish reach a high abundance in the study area by the end of summer, when the grown juvenile sleave shallow waters. In the autumn period, the fish redistribution and a significant increase in the abundance occur in the area of heated waters compared to the back ground sites. The results obtained indicate the absence of an environmentally significant lethal effect. Local plankton losses are quickly compensated due to high reproduction rates and short-cycle development of invertebrates. The lethal effect of exposure to high temperatures on fish was not found.

The present study aimed to assess the status of successive dams on surface water quality, especially in reducing organic pollution levels, and their effects on the ecological life were investigated. Water samples were collected seasonally from three dam’s monitoring stations. Temperature, pH, dissolved oxygen, electrical conductivity, turbidity, ammonium nitrogen, nitrite nitrogen, nitrate-nitrogen, sulfate, total phosphorus, chemical oxygen demand, biochemical oxygen demand and total hardness parameters were measured in surface waters. The Geographic Information System (GIS) was used to produce thematic maps of the investigated parameters. Stations used as point feature layers were mapped using quantitative labeling via symbology. The results were compared with Turkish Regulation, 2015 and EC Directive on the quality of fresh waters needing protection or improvement to support fish life (2006) guidelines. According to the results of the analysis, Dams that are located one after the other contribute to the partial cleaning of the water by resting. Sarıyar, Gökçekaya, and Yenice Dams were built on the Sakarya River, which is one of Türkiye’s biggest and most significant river systems, for electric supply and utility of water for irrigation and fishery activities. Gökçekaya Dam Lake was built between Sarıyar Dam and Yenice Dam, which are situated in the same line of Sakarya River. Gökçekaya and Yenice Dams are fed by Sarıyar Dam Lake and do not receive fresh water. The fact that the three dams are established one after the other aids in the water’s resting and the aids in removing the suspended solids/suspended load. But, this research show that domestic, industrial, agricultural wastes carried by the branches of the rivers caused algal blooms in Dam lakes, especially which are not fed with fresh water. Due to organic pollution the decrease in dissolved oxygen, especially from time to time, negatively affects the ecological life in the lakes.

The purpose of the study was the ecological and faunal study of dragonflies of the south-east of Belarus. New data for 38 species are reported. Three dragonfly species of them are new for this region: Erythromma viridulum, Epitheca bimaculata, Leucorrhinia pectoralis. Zoogeographically, trans-Eurasian and European dragonfly species predominate. The most numerous is the family Libellulidae. Most of the collected dragonfly species are widespread and numerous on the territory of the south-east of Belarus. Rare for the region are Sympecma fusca, S. paedisca, Erythromma viridulum, Ophiogomphus cecilia, Epithecia bimaculata, Somatochlora metallica, Orthetrum brunneum and Leucorrhinia rubicunda. The location is indicated and brief information about the distribution and ecological and biological characteristics of each species is given.

The three groups of mollusks of the triploid Pacific oyster Crassostrea gigas from the Liman Donuzlav (Black Sea), differing in morphometric characteristics: fast growing (FG) – shell height (H) > 40 mm, medium growing (MG) – 15 mm < H < 40 mm and slow growing (SG) – H < 15 mm, were studied. The stable differences in the growth rates of juveniles of the same age were revealed. Mollusks of the FG group were the leaders in terms of weight gain and linear size throughout the study. The average daily increase in shell height in the studied mollusks ranged from 0.1 to 0.35 mm/day, with maximum values in June and September. Weight gain occurred with different intensity, on average in SG – 0.051 g/day, in MG – 0.168 g/day, in FG – 0.287 g/day. The peaks of this indicator were in August and September, reaching 0.12, 0.26 and 0.43 g/day, respectively. A negative allometry of the shell in height was obtained in slow–growing polyploid oysters (b = 2.17), in the other two other groups – a clear positive (for MG b = 3.23, for FG b = 3.80), i.e., the increase in mass was faster than linear growth in juveniles of the species. Polyploidy (triploidy) is suggested as the reason for the differences in the growth rates of the same-aged mollusks. The allometry indicator b can be used to identify growth features in the early stages of oyster development.

Morphological variations of the Asian sheat catfish, Wallago attu (Bloch and Schneider, 1801) sampled from the rivers Gomti, Ganga, Yamuna at Lucknow, Kanpur and Agra districts in Northern India, river Hooghly at Kolkata in Eastern India and river Pampa at Kerala in Southern India were analyzed in the present study. Images of 261 specimens of W. attu were taken without harming the fish to evaluate the morphometric variation using 8 digitized homologous landmarks for truss analysis and geometric morphometrics. Size corrected morphometric variables were analyzed using analysis of variance (ANOVA), multivariate analysis of variance (MANOVA), principal component analysis (PCA) and discriminant function analysis (DFA). Coefficients of all PCs were positively and negatively correlated to 31 significant (p < 0.001) truss measurements due to variations in size and shape. Morphometric measurements lying in the head region such as head length (HL), eye diameter (ED), inter-orbital length (IOL) and snout length (SNL) contributed most to differentiate the populations in truss analysis. The ED, HL, SNL and IOL of Yamuna fish was significantly (p < 0.001) smaller than the other fish populations. This could be attributed to the heavy pollution load in the Yamuna River and differences in the feeding regimes of fish. PCs and relative warps depicted differences in geometric analysis because of body shape variations among different river populations. The scatter plot in DFA revealed the presence of three distant and different phenotypic groups of W. attu among five wild river populations of fish with 70.5 and 83.9% of correct classification of fish into their original groups in truss and geometric analysis respectively. A single homogenous stock of fish was found to be in the rivers Gomti, Ganga and Hooghly because of a high level of intermixing (maximum misclassification) among the three river populations, whereas Yamuna and Pampa populations were two non-overlapping isolated groups due to negligible intermixing. These variations in the present study might be the effect of geographical isolation and river fragmentation due to the change in habitat that restricts fish movements. This is the first report on the morphometric assessment of W. attu that provides base line data for further confirmatory stock studies that would be useful for conservation and sustainable management of this vulnerable fish.

According to the saprobity index, estimated by the phytoplankton biomass, the degree of organic pollution of ecotone areas (the mouth of the Il’d River and the littoral of the Volga reach of the Rybinsk reservoir) was determined. The saprobity index in protected shallow waters was 1.83 in 2009 and 2.07 in 2010; in the pelagial – 2.14 and 2.13 in 2009 and 2010 respectively. In the “river-reservoir” system, the lowest average values of the saprobity index were noted in the mouth area of the Il’d River: in 2009 – 1.94, in 2010 – 1.87, in 2011 – 1.88. In the river and the reservoir, its values were higher: 2.05 and 2.07 in 2009, 1.96 and 2.08 in 2010, and 1.97 and 1.99 in 2011 respectively. The decrease in saprobity in shallow waters and at the mouth of the river, compared to the bordering water, indicates a higher intensity of self-purification processes, which can ensure the sustainability of the ecosystem of the reservoir as a whole. Abnormal weather phenomena, in particular, high summer water temperatures, can lead to destabilization of the features of ecotone algocenoses, as a result, to a violation of the process of self-purification of the reservoir.

This paper presents the first data on the content of plant pigments in the bottom sediments of the Uvod Re-servoir (Volga basin, Russia), unique in its hydrological regime, which support the hypothesis of more intensive carbon accumulation in small water bodies. It is established that the average concentration of chlorophyll a and its transformation products at the stations is 62.6 ± 10.0 μg/g dry sediment, 35.2 ± 4.5 mg/(m² mm) of wet sediment, and 0.73 ± 0.09 mg/g organic matter of sediments. The ratio of organic carbon to the pigment concentration varies within 400–6000 depending on the type of bottom sediments, which significantly exceeds the values known for macrophytes and phytoplankton. Despite the features of hydrodynamics and geomorphology of the reservoir, the spatial distribution of sedimentary pigments is consistent with the structure of the bottom sediment complex, which is typical for water bodies of different types. A decrease in differences between the pigment concentrations in the sandy and silty biotopes of the Uvod Reservoir compared to the Upper Volga was noted. Average concentration of chlorophyll a with pheopigments (58.5 ± 6.7 μg/g of dry sediment), calculated considering the areas of bottom sediments of different types, in the Uvod Reservoir is 2.3 times higher than in the Gorky Reservoir (25.3 ± 1.5 μg/g), from which water inflows through the Volga–Uvod Canal. According to the content of sedimentary pigments, the trophic state of the reservoir is mesotrophic. Features of eutrophication in the Uvod Reservoir are more distinctly expressed than in the Gorky Re-servoir.

For the first time, the effect of a patented alcoholic solution of algicide on seed germination and the development of seedlings of three species of helophytes Sparganium emersum, S. glomeratum and Schoenoplectus lacustris was studied based on gallic, tetradecanoic, heptane and octane organic acids. Significant differences were found in the effect of different algicide concentrations (0.1, 1.0 and 10.0 mg/L) on seed germination and the initial stages of seedling development of three species of helophytes. We observed the stimulation of germination of Sparganium emersum seeds at a concentration of 10.0 mg/L and inhibition of this process in S. glomeratum at concentrations of 1.0 and 0.1 mg/L. No significant effect of algicide on the germination of Schoenoplectus lacustris seeds was found. According to the degree of increase in the resistance of morphological parameters of plants to the effect of different algicide concentrations, seedlings of three species of helophytes are arranged in the following series: Schoenoplectus lacustris > Sparganium glomeratum > S. emersum.

The taxonomic composition and quantitative characteristics of zooplankton and zoobenthos of some reservoirs of natural origin of the Norilsk industrial district and adjacent territories after a man-made accident have been determined. In most sample collection points, all age groups of many invertebrates are marked. The Daldykan River above the confluence of the Bezymianny Сreek and the source of the Pyasina River represent a poorly disturbed watercourses and can serve as a norm for organizing recovery activities.

The results of long-term studies of biting midges (Diptera, Ceratopogonidae) in macrozoobenthos communities of five saline rivers of the hyperhaline Lake Elton basin are presented. The fauna of Ceratopogonidae includes 5 halophilic and euryhaline species, among which representatives of the tribe Palpomyiinae predominate. Taxonomic composition of the family differs in rivers with different levels of salinity. Species Sphaeromias miricornis and Culicoides riethi are widely distributed in mesohaline the Khara, the Lantsug and the Bolshaya Samoroda rivers, and P. schmidti widely distributed in polyhaline the Chernavka and the Solyanka rivers. Two generations of S. miricornis and three generations of P. schmidti were recorded. Departure of the first generation of P. schmidti occurs in mid-May, S. miricornis in late May–early June. There is an increase in mean annual abundance and biomass of biting midges in polyhaline rivers compared to mesohaline rivers.

The influence of mtDNA cytochrome c-oxidase I gene fragment variability on body length was studied in twelve species of cyprinids, which may have hybrids with Rutilus rutilus L. and Abramis brama L., and in reciprocal hybrids (RA, AR) and alloplasmatic backcrosses (_ARR, _RAA) of roach (R) and bream (A). It has been established that the rate of nucleotide substitutions in COX1 is negatively related not only to body size but also to fish life span, which differentiates them into two groups: group I – species with a high rate of COX1 changes and a relatively small body size and group II – species with low sequence variability and relatively large body size. The boundary for the distinguished groups runs between species the same genus Leuciscus leuciscus and L. idus: with a twofold decrease in the rate of substitutions in ide, a twofold increase in body size and lifespan occurs, which indicates a decrease in the rate of cellular respiration and free radical leak, and the exact mitonuclear match respiratory complexes. Presumably, the decrease in the rate of COX1 changes in species of group II and in bleak Alburnus alburnus is associated with an increase in the size of genome, which provides additional protection of genes from chemical mutagens and, regardless of body size, reduces the rate of aerobic metabolism. It has been experimentally shown that mtDNA affects body length. When bream mtDNA is included in the roach nuclear genome, _ARR backcrosses have the body length of a bream and high viability, while _RAA backcrosses with roach mtDNA and the bream nuclear genome inherit the roach body length and reduce viability. Species of group II are not able to effectively use the highly polymorphic mtDNA of species of group I, which is also manifested by a violation of the inheritance of a longer bream body length in RA hybrids and leads to reproductive isolation. Group I species, such as Rutilus rutilus, can include mtDNA of both groups in their genome, which underlies sexual selection in hybridization. Accordingly, sexual size dimorphism has a genetic origin, and body size for a potential partner can be a signal for determining the mitonuclear compatibility of genomes in respiratory complexes.

The genus Erythroculter (Cypriniformes, Cyprinidae, Abramidinae) is one of the most commercially important freshwater fish species inhabiting China. However, very limited information is available regarding genetic variation among Erythroculter species, therefore hindering their effective management. In this regard, microsatellite markers and sequences of mitochondrial COII and D-loop were analyzed to investigate the genetic variation among three species of genus Erythroculter. Results demonstrated that 11 microsatellite loci were amplified effectually, and the size of allele was 110–350, 94–338 and 86–384 bps in E. ilishaeformis, E. dabryi and E. mongolicus respectively. Average number of allele was 5.82, 5.73 and 6.45 per locus for E. ilishaeformis, E. dabryi and E. mongolicus respectively. Fragments of COII and D-loop was 675 and 929 bps respectively. On the basis of Shannon’s information index, heterozygosity, polymorphic information content and nucleotide diversity index (P), the microsatellite and nucleotide diversity of E. ilishaeformis was most abundant, and that of E. mongolicus was least abundant. Based on the haplotype distribution of D-loop or the allele size in microsatellite loci of EI19 or HWB05, it could be distinguished perfectly among E. ilishaeformis, E. dabryi and E. mongolicus. Some historical and environmental elements might result in the high genetic divergence and promote the speciation of E. ilishaeformis, E. dabryi and E. mongolicus. These results would be of avail in the conservation and sustainable utilization of these three species.

For the first time data on parasite diversity of Syngnathidae fishes inhabiting the Black and the Sea of Azov, the rivers flowing into these seas and their estuaries accumulated in more than 30 articles and books during almost one century of investigations were summarized. A high level of parasitic organisms’ richness is registered to date: 64 species from 45 genera, 35 families, 14 classes, 10 phyla have been recorded here from 8 species of Syngnathidae fish hosts: Syngnathus abaster Risso, 1827, S. acus L., 1758, S. schmidti Popov, 1927, S. tenuirostis Rathke, 1837, S. typhle L., 1758, S. variegatus Pallas, 1814, Nerophis ophidion (L., 1758), Hippocampus hippocampus (L., 1758). Host-parasite and parasite-host lists are provided, the results for Kinetoplastida, Sporozoa, Microsporidia, Myxozoa, Ciliophora, Platyhelminthes (Monogenea, Trematoda, Cestoda), Nematoda, Acanthocephala, Annelida, and parasitic Arthropoda are presented. Platyhelminthes and Ciliophora (19 and 18 species, respectively) turned out to be the most species-rich taxa of Syngnathidae parasites, while Trematoda was the richest (15 species) class among flatworms. The largest number of parasite species is known from three fish hosts: S. abaster parasite fauna comprises 54 species of 10 phyla (84% of total parasite fauna of this fish family in the region), S. typhle – 27 parasite species belonging to 6 phyla (38%) and relatively pure parasites fauna in H. guttulatus, 14 species of 6 phyla (22%).

In order to assess the impact of cyanobacteria on mollusks under experimental conditions, the interaction of toxic and non-toxic strains of cyanobacteria Microcystis aeruginosa (Kützing) Kützing and bivalve mollusks Unio pictorum (L., 1758) was studied. Cyanobacteria have a negative effect on bivalve mollusks: 40% death of mollusks and deterioration of their adaptive capacity were recorded when co-cultivated with M. aeruginosa at a high cell concentration. At the same time, there was no difference in the mortality of mollusks incubated with toxic and non-toxic cyanobacteria. A decrease in the content of microcystin LR in the presence of bivalves was revealed. No statistically significant increase in the number of cyanobacteria in the water was noted after transit passage through the digestive system of bivalves.

The cellular composition of the peripheral blood of the Baikal seal Phoca sibirica (Gmelin, 1788) has been studied. In blood smears, various cells were found: large and small lymphocytes, monocytes, neutro-, eosino- and basophils. Analysis of the leukogram showed the predominance of neutrophils and lymphocytes among white blood cells. The proportion of the content of various forms of leukocytes corresponded to similar data of marine representatives of true seals (Phocidae).

During the study of parasites of the ninespine stickleback Pungitius pungitius, a resident in the Volga basin, intestinal nematodes Pseudocapillaria tomentosa and Rhabdochona denudata were found. Both species are recorded for the first time in the parasite fauna of the host of the European part of Russia. Data on the occurrence and intensity of fish invasion by worms are presented.