Trematodes Sphaerostoma globiporum Rudolphi, 1802 were found in the Angara River (a tributary of the Yenisei River, Eastern Siberia) in the roach Rutilus rutilus (33.3
The first data on the species composition of Bacillariophyta has been obtained in the phytoperiphyton of 12 lakes of the Karelian Isthmus using scanning electron microscopy. Altogether, 126 species and varieties of Bacillariophyta from 47 genera have been found, including 3 new to the flora of Russia, and 21 algae were identified to the genus level. The highest species diversity was found among centric diatoms of the genus Aulacoseira (ten species) and pennate algae of the genera Eunotia (13) and Gomphonema (18). The minimum species taxonomic diversity was observed in lakes Vorob’evo, Mikhalevskoe, and Gorskoe (from 7 to 14), and the maximum one was in lakes Naryadnoe, Leskovo, and Belokamennoe (from 41 to 44).
In July 2022, the coastal waters of the Eastern Shelf of the Middle Caspian and the state of the crayfish populations (Astacidae) were studied. Data on the state of the environment has been obtained, and the thermal stratification of water was recorded at the site’s depth drop. The features of the location of crayfish biotopes, their distribution, and species were studied and the sexual composition of population was measured. The biological characteristics of crayfish, their behavior, and the degree of their disease exposure depending on their habitat and conditions are noted and substantiated. It is established that one species of crayfish, the long-clawed Caspian crayfish Pontastacus eichwaldi Bott, 1950, inhabits the study area. The density of crayfish aggregation ranged from 0.03 to 0.23 specimens/m2; it was lowest in the sandy biotope and highest in the stone biotope. The ratio of females to males in the population is three to one. The commercial stock of crayfish reaches 18 t; the total permissible catch is 4.5 t. The prevalence of rusty spot disease in males is 3
The study of the composition, abundance, biomass, and trophic structure of macrozoobenthos in watercourses of various sizes in the southern part of the Olonets Isthmus, most of which belong to the basin of the River Svir, was conducted during the summer seasons of 2011–2023. A total of 207 species of macrozoobenthos were identified in the rivers, with a dominance of chironomids, caddisflies, and mayflies. The riffle areas were characterized by significantly higher abundance (5970 individuals/m2) and biomass (18.21 g/m2) compared to the pools (1540 individuals/m2 and 2.16 g/m2, respectively). All groups were represented in the trophic structure, except for scrapers. An increase in the proportion of collector-gatherers was noted in the pools. Riffle areas exhibited higher β-diversity and expected species richness (278 species) compared to pools (165 species). It was shown that, under conditions of relatively thin layers of sediment, the macrozoobenthos of the rivers combines features of both riffle (high species richness and abundance) and pool rivers (low species richness and abundance).
In 2021–2023, an assessment of the physicochemical parameters of water and the structure of zooplankton communities was conducted in the lakes of the Volzhsko-Kamsky Nature Reserve following pollution by wastewater from a poultry farm and a fur farm. The findings indicate that the lakes still exhibit signs of anthropogenic impact, including elevated nutrient content, hydrogen sulfide presence, and low water transparency. Despite this, zooplankton demonstrates high species diversity (140 species), suggesting partial ecosystem recovery. The highest biodiversity is recorded in Lake Ilantovo (125 species), whereas lakes Linevo and Gniloe are dominated by pollution-tolerant species. The trophic status of the water bodies ranges from mesotrophic to eutrophic, with periodic biomass surges. The results indicate ongoing natural recovery processes, but also persistent ecosystem transformation due to residual pollution.
The effect of tris(chloropropyl)phosphate (TCPP), an organophosphorus ester, at concentrations of 100, 500, and 1000 nanograms per liter (ng/L) on the growth of the aquatic plant Lemna minor was studied. The effect of TCPP on the population size of L. minor has been found. A higher specific growth rate, as well as the appearance of more fronds by the end of the experiment were detected in the medium with the lowest concentration of TCPP. At the highest concentration of TCPP, the daughter fronds failed to separate from the mother plant, leading to the formation of large colonies. The number of fronds within these colonies could reach as high as 18. As a result, the actual production of the L. minor population was lower than the potential one due to the lack of maternal fronds to produce new plants.
The purpose of the study was to assess the distribution and assemblage pattern with their environmental responses in a pristine river, the Belan, from the Neolithic geological period of the Vindhyan region in North Central India. The diatom samples were collected at 5 distinct locations along approximately 180 km long the river Belan. The samples for physicochemical parameters and diatoms were collected during the period from November 2021 to October 2022. Diatom samples were obtained by scraping a 3 × 3 cm2 area of the substratum through a standard procedure. The permanent slides of diatoms were prepared by acid treatment and NAPHRAX mounting for valve count of each sample. The following species: Aulacoseira granulata (Ehrenberg) Simonsen (10.8
Long-term dynamics of age, body size, and body mass in Russian sturgeon of the Caspian population has been analyzed based on the data of trawling survey. The rejuvenation of the population and a decrease in the mature part of population abundance has been found, particularly after a ban on sturgeon commercial fishing, which was a response to extensive poaching. These tendencies indicate a decrease in the reproductive potential of the Russian sturgeon population. It is found that Russian sturgeon females have higher growth rate in body length and mass than males. In 2004–2020, the sturgeon growth rate in body length and mass and fecundity decreased when compared with 1991–1998 due to a decline in its trophic conditions resulting from the invasion of the ctenophore jelly Mnemiopsis leidyi and the mass mortality of kilka (Clupeonella)—an important component of sturgeon food.
Five species of carp fish (roach, rudd, bleak, white bream, and ide) have been studied in the Usman River in the Voronezh Nature Reserve, and four species of opisthorchiid metacercariae have been found (Opisthorchis felineus, Pseudamphistomum truncatum, Metorchis bilis, and M. xanthosomus). Data on the extensiveness and intensity of fish infestation with opisthorchiids vary significantly in certain sections of the river. Anthropogenic pollution of the river increases eutrophication and reduces the biodiversity of opisthorchiids. A significant increase in the indices of fish invasion by metacercariae is noted in the protected sections of the river, indicating stable circulation of opisthorchiids. Bleak, roach, and rudd are considered to be the leading link in the accumulation of metacercariae. At the same time, bleak bears the main burden in the circulation of the four-species community of these trematodes. Bleak is characterized by wide host plasticity and high accumulation of all types of opisthorchiids. The assessment of the infection indices of carp fish represents the share of a certain type of opisthorchiids in the community structure, where Pseudamphistomum truncatum dominates (>60
Lake Maly Terenkul in the Southern Urals was oligotrophic about 100 years ago, but after years of pollution from domestic waste, it has become a eutrophic–polytrophic body of water with a massive growth of cyanobacteria. The lake was not studied during the period of oligotrophy. An attempt was made to theoretically reconstruct the composition of the main components of zooplankton—rotifers, copepods, and cladocerans—that inhabited the lake a century ago. For this purpose, materials on the autecology of rotifers and crustaceans were used based on scales of trophic and thermal indicator properties of species previously developed by the author. It has been shown that trophic status is a key factor determining the composition of zooplankton, which is formed in interaction with the fauna of neighboring lakes. An algorithm for the theoretical reconstruction of lake fauna is proposed that includes the determination of the potential trophic status of the water body, an analysis of the current composition of zooplankton and identification of the reasons for its formation in the observed form, the identification of potential sources of immigration into the water body (and especially the “parent” water body, immigration from which had a decisive influence on the formation of zooplankton), and adoption of the composition of its fauna as the basis for reconstruction.
Study presents information on alien fish species of the Volga and Kama rivers. The share of alien species in the total number of fish species in the catch in the Volga River basin varies from 8–10
Cell parameters of peripheral blood of Danio rerio (Hamilton, 1822) exposed for 30 days to aqueous solutions of dimethyl disulfide (DMDS) of different concentrations were studied, using light microscopy. It was shown that significant changes in the analyzed parameters were observed only at a DMDS concentration of 5 mg/L. There was a shift in the leukocyte formula towards a decrease in lymphocytes and an increase in the proportion of granulocytes (mainly metamyelocytes and band granulocytes). The proportions of other cell types did not exceed 2–6
The growth characteristics of individuals of the garfish Belone belone euxini Günther, 1866, caught with a hook and line gear in the northeastern part of the Black Sea off the coast of southeastern Crimea, have been studied. A total of 412 specimens of garfish were examined in 2019–2022; 246 were females, 153 were males, and the sex of 13 individuals was not determined. The range of total length (TL) of the garfish specimens (17.0–57.3 cm) is generally consistent with the results of previous studies conducted in the Aegean (26.0–54.5 cm), Mediterranean (24.2–55.0 cm), and Black (22.2–61.1 cm) seas. The portion of females in the population of garfish caught off the coast of southeastern Crimea was higher than the portion of males (1.61 : 1), which was also noted by other authors when studying fish of this species living in the Aegean (1 : 0.45), Mediterranean (2.36 : 1), and Black (1.9 : 1 in 2006 and 1.07 : 1 in 2014) seas. The maximum age was 7 years. The dominant age group was 3 years. The parameters of the Bertalanffy function for linear and weight growth were as follows: for females L∞ = 43.00 cm, W∞ = 89.68 g, k = 0.5871 year–1, and t0 = –0.6527 year; for males L∞ = 44.96 cm, W∞ = 100.83 g, k = 0.2978 year–1, and t0 = –2.5656 year; and for all individuals L∞ = 59.26 cm, W∞ = 239.52 g, k = 0.2027 year–1, and t0 = 1.4941 year.
The present study explores the symbiotic relationships between the common freshwater mussel Lamellidens marginalis and two associated symbionts: water mites (Unionicola spp.) and ciliates (Conchophthirus spp.). Host mussels were collected from Banipur, Habra, West Bengal, India between August 2024 and March 2025, focusing on the prevalence, anatomical localization, and morphological diversity of the symbionts. Water mites exhibited a high prevalence of 71.8
The small water bodies associated with croplands in the Western Ghats region support the cultivation of Catla catla (Hamilton, 1822) to meet local fish demand. Although fish farming is commonly practised on a small scale, there is little information on the potential impacts of agrochemicals and heavy metals in these water bodies. In this study, we aimed to evaluate the health status of C. catla by examining the effects of heavy metals on the occurrence of erythrocytic and nuclear abnormalities, which are known indicators of fish health. We observed nine types of erythrocytic cellular abnormalities (ECA) and seven different nuclear abnormalities (ENA) in the fish C. catla cultivated in small water bodies located within rice paddy fields. Incidences of ECA and ENA clearly showed a significant difference between the three sites (S1, S2, and S3: P < 0.01). The water temperature, pH, and dissolved oxygen content did not correlate with the incidence of ECA and ENA. The pesticide content of water and sediment was below the detectable range. Compared to sediment, the heavy metal content of the water was low, however, it has a high value (>100) for heavy metals pollution index (HPI). Mn in water and Cu and Cd in sediment showed differences between sites (P < 0.05). The ECA increased with Zn and Pb sediment content in S1, while ENA showed an increase with Zn and a decrease in the Mn content of water and sediment in S2. Overall, the heavy metal content of Pb and Zn showed a strong influence on the occurrence of abnormalities. The occurrence of numerous erythrocytic and nuclear abnormalities at a high prevalence reflects the poor health status of fish cultivated in small water bodies within rice paddy fields.
Freshwater ecosystems have been among the most vulnerable habitats globally over the past 50 years. These ecosystems have experienced varying degrees of decline due to a combination of global changes, including anthropogenic activities and climate change in recent decades. As a result, monitoring the diversity of freshwater ecosystems and their biota has emerged as a hotspot area of research in light of this diminishing variety. Environmental DNA (eDNA) has emerged as a powerful, complementary tool, offering a rapid, non-invasive alternative for biodiversity monitoring. eDNA represents an environment-friendly and cost-effective method for identifying and quantifying taxa without harming native species or habitats. The genetic material, consisting of short DNA fragments or cellular components released by aquatic organisms through skin, urine, feces, mucus, and cellular debris into environments like water, air, soil, or sediment, enables species identification and the characterization of community composition. The use of eDNA has expanded significantly in recent years, particularly in freshwater ecosystems in China, demonstrating its utility across various ecological and conservation applications. However, challenges remain, particularly regarding false positives and false negatives, which affect its reliability. This highlights the need for rigorous calibration and validation at each stage of analysis. Additionally, advancing eDNA technology requires a better understanding of the ecological and physical processes that influence eDNA dynamics, including its production, persistence, degradation, and transport. This review provides Chinese researchers, as well as non-molecular biologists, with a clearer understanding of the eDNA metabarcoding concept and its methodological overview.
Global river ecosystems face growing threats from pollution and habitat degradation, creating an urgent need for efficient and interpretable health assessment tools. The Biological Monitoring Working Party (BMWP) index is widely used for water quality evaluation but suffers from low efficiency and subjectivity due to reliance on expert judgment and limited ecological representation. To improve its application, we analyzed 161 benthic macroinvertebrate samples from the Key River Basins in Hainan Province, China, and developed several machine learning models, including LASSO regression, to predict BMWP values. The LASSO model outperformed others, achieving R2 = 0.88, demonstrating strong stability and generalization. SHAP analysis identified the Shannon diversity index, number of sensitive taxa, and Hilsenhoff index as key drivers of BMWP variation: higher diversity and sensitive taxa indicated better water quality, while the Hilsenhoff index reflected higher pollution risks. Based on these insights, BMWP values were classified into five risk levels, each corresponding to distinct ecological conditions, with significant differences in indicator distribution supporting their ecological basis. Spatial analysis revealed high-risk clusters in the upper and lower reaches of the Changhua River, a downstream gradient along the Nandu River, and overall better conditions in the Wanquan River. These findings highlight priority areas for ecological management. The integrated framework—combining prediction, interpretability, and early warning—provides a systematic approach for ecological risk identification and spatial conservation planning in tropical river systems.
This is the first record of the alien species Lychaete herpestica (Mont.) M.J. Wynne from the Black Sea. This macroalga is of Indo-Pacific origin and was previously included in the database of Exotic Macrophytes in the Mediterranean Sea developed by a CIESM. The immigrant species was found in the water area of the Cape Martyan Nature Park located at the Southern coast of Crimea (SCC) in the pseudolittoral zone. This corresponds to its confinedness to the littoral zone within its modern range limits. The studied specimens correspond to the taxonomic diagnosis, their key morphological and morphometric characters are specified for the new region and illustrated. The species entry into the Azov-Black Sea Basin probably occurred as a result of accidental introduction with a spat of mollusks directly from the primary range in 2023–2024. Within the boundaries of the new region, L. herpestica can widely disperse and successfully naturalize, while its development will likely have a pronounced seasonality peaking in summer. However, given its narrow biotopic confinedness and increased vulnerability to hydrodynamic factors, mass development of the species with subsequent structural transformation of native communities is unlikely. At the same time, the import of hydrobionts from donor regions and self-dispersal of invasive species from the Mediterranean Sea leave no doubt that the detection of new alien macrophytes in the Black Sea and the Sea of Azov will become more frequent. Against the background of global climate change, naturalization of some of them may seriously affect the structure of biota and the state of the natural environment of this semi-enclosed basin.
Beetles of the family Heteroceridae are characteristic inhabitants of contour biotopes; as algodetritophages, they are involved in processing of organic matter included in the detrital food webs and in transfer of the matter and energy in the ecotone zone at the interface of two “water–land” environments. Collection and preservation methods, as well as methods of primary processing of the collection material are discussed in detail. The general ecology and biology of the family Heteroceridae are described. The paper is abundantly illustrated with photographs and drawings.
The effect of short-term exposure to a low-frequency electromagnetic field (50 Hz, 10 μT) and thermal stress (water heating at a rate of 8°C/h) on amylolytic and proteolytic activities (AA and PA, respectively), maltase activity (AM) in the intestine, acetylcholinesterase (AChE) activity, and water-soluble protein (WSP) content in the brain of juvenile Prussian carp Carassius gibelio fed a specific diet for 2 months with low (LMC; 0.07 mg/kg wet weight) and high (HMC; 0.182 mg/kg wet weight) mercury content have been studied. After 1st and 2nd months of exposure mercury content in the fish muscles of the HMC group (0.40 and 0.66 mg/kg, respectively) was approximately 2 times higher compared to the LMC group (0.22 and 0.30 mg/kg, respectively). After 2 months of the experiment, AA increased by 30–48
