Phytoplankton as an indicator of the current ecological status of the Ob River

The species composition, taxonomic structure, and the dominant complex of algae, and the distribution of phytoplankton abundance in the studied watercourse were identified based on data obtained for phytoplankton from the Ob River (from Tomsk to Salekhard) in summer 2019. Green algae (division Chlorophyta) make up the basis of the phytoplankton abundance in the river. The dominant complex is represented mainly by centric diatoms (genera Aulaсoseira, Cyclotella, Stephanodiscus) and non-heterocyst forms of cyanoprokaryotes (genus Aphanocapsa). The numbers and biomass of phytoplankton gradually decrease downstream of the Ob River; below the confluence of the Irtysh River, the edge effect occurs: increase in the diversity and density of organisms at the boundaries of ecosystems. Compared to the previous studies, the proportion of green and euglena algae, and cyanoprokaryotes in the taxonomic spectrum of phytoplankton increased, the composition of the dominant complex enriched, including due to non-heterocyst forms of cyanoprokaryotes, and the trophic status of the river increased to the category of eutrophic waters.

Potentiometric Study of the Copper(II) Ions Complexation Process with Thiourea in Acidic Medium

Potentiometric titration method was used to study the copper(II) ions complexation process with thiourea in medium containing 1 mol/l of hydrochloric acid at a temperature of 298 K. It was found out that mononuclear (CuTMn) and binuclear (Cu2TMn) complexes were observed in the copper(II) --- thiourea system depending on the copper ions concentration. It was determined that in acid medium with copper(II) ions concentration less than 5 · 10--4 mol/l and mononuclear complexes of the composition are generated in the system, which constant is equal to lg β3 = 11.9. With an increase in the copper(II) ions concentration (CCu+2 > 5 · 10--4 mol/l), binuclear thiourea complex dominates in the system. Stability constant logarithm of the Cu2TM6 composition binuclear complex is equal to 27.5 and was calculated using the modified Leden's method. Based on the constants, complexes existence regions were determined depending on the ratio CTM/CCu+2. With the CTM/CCu+2 ≥ 5 relations, existence of a dominant complex significantly depends on the copper(II) ions concentration. It turned out that fractions of all complex particles were growing with an increase in the copper(II) ions concentration in the system. It was found that stability of thiourea complexes in the CuLi2+, AgLi+, AuLi+ rows was increasing

ZOOPLANKTON OF SMALL LAKES IN THE EASTERN PART OF THE CATCHMENT AREA OF LAKE VOZHE (VOLOGDA OBLAST)

In the summer period of 2017–2020, the authors studied the composition, dominant complex and the abun-dance of zooplankton in 23 small lakes in the eastern part of the Lake Vozhe catchment area (Vologda oblast). The lakes are located in lacustrine-glacial, moraine-hilly and moraine-plain landscapes. A total of 121 species are recorded in zooplankton of the lakes (Rotifera – 38, Cladocera – 56, Copepoda – 27) including Holopedium gibberum, Daphnia pulex, Bunops serricaudata, Paralona pigra, Chydorus ovalis, Acanthodiaptomus denticornus denticorn that are relatively rare species for the region. The highest occurrence is typical for eurybiontic species. The planktonic fauna of the waterbodies of lacustrine-glacial terrains is sui generis (the index of similarity with other lakes is 0.4). The level of similarity in the composition of zooplankton in moraine lakes is 0.7 on average. Zooplankton in the lakes of different landscape types differs in the structure of dominant complex. The set of dominants in the reservoirs of the lacustrine-glacial terrains is sui generis (Keratella cochlearis, Daphnia galeata, Eudiaptomus graciloides, Heterocope appendiculata). The composition of zooplankton dominants in moraine lakes is more diverse. Most of these waterbodies are dominated by Kellicottia longispina, Keratella cochlearis, Bosmina longirostris, Thermocyclops oithonoides. In the lakes of the moraine-hilly landscape, the set of dominants also includes Eudiaptomus gracilis and E. graciloides, and in the moraine-plain water bodies Asplanchna priodonta, Diaphanosoma brachyurum, Ceriodaphnia pulchella, Polyphemus pediculus are dominant. The highest average abundance (137.7 thousand ind./m3) and biomass (1.8 g/m3) are typical for the lakes in moraine-plain landscapes. The morphology of the depressions of these lakes contributes to the development of macrophyte thickets. The abundance and biomass of zooplankters in waterbodies of the lacustrine-glacial landscapes are 58.9 thousand ind./m3 and 0.8 g/m3, respectively. The development of macrophytes in these reservoirs is limited by a rapid increase in depth and the predominance of peat and peat-silt soils.

Response of communities of water organisms to anthropogenic changes in mineralization small steam (White Sea basin, Republic of Karelia, Russia)

An increase in water mineralization in the Kenti River has occurred as a result of mining at the Kostomuksha iron ore deposit (Republic of Karelia, north-west of the European part of Russia); it has become a relatively new type of anthropogenic impact. Meantime, the total mineralization of water in the upper reaches of the Kenti River reached 800 mg/L. The species composition, abundance and biomass of phytoplankton, phytoperiphyton, zooplankton, and zoobenthos were analyzed. The influence of natural and anthropogenic factors on the chemical composition and formation of the structure of aquatic biocoenoses was assessed. The trophic status of the river, its saprobity, and the significance of particular communities and biotic indices for bioindication of the ecological state was studied. Dominant complex of the Kenti River was represented by a small number of species that were resistant to the dynamic load of water. The abundance and biomass of phytoplankton, phytoperiphyton, zooplankton, and zoobenthos made it possible to conclude on rather high degree of their development in river, as well as on their vital activity and flexibility. It was then reported on the ability of the river ecosystem to restore.

MACROFAUNA OF INVERTEBRATE OF LAKE NERO

The taxonomic composition of macrobenthos of Lake Nero and the mouth area of the river Sarah are shown. The main part of the benthos in the summer in the lake is formed by larvae of amphibiotic insects – chironomids, biting midges and mayflies. The macrobenthos of the lake and the mouth of the Sara River can be characterized as chironomid species complex. Relative to the results of previous studies, changes occurred in the dominant complex, a decrease in the total biomass of macroinvertebrates was noted. Together with a decrease in the species diversity, the only one dominant species (Chironomus f.l. plumosus) indicates a decrease in the homogeneity of the structure of benthic communities and its simplification. A decrease in the species richness, occurrence and density of oligochaetes was observed in comparison with the data of other studies. In contrast benthic communities, aquatic plants biotopes can be characterized as more favorable for both benthic and fitophilic invertebrates. The large number of invertebrate species makes it possible to evaluate the thicket as a biotope with very favorable environmental conditions. Rheophilic, limnophilic and obligate benthic species occurring here can coexist, rising from the bottom into thickets with a favorable oxygen regime, which allows them to survive in conditions of oxygen deficiency.

Phytoperiphyton of watercourses from the White Sea Basin (Murmansk District, Republic of Karelia, Russia)

The results of phytoperiphyton studies in 92 watercourses of the White Sea basin are summarized and analyzed. Totally 540 taxa with a rank below the genus were identified. They belong to six divisions: Cyanophyta – 76, Ochrophyta – 374, Euglenophyta – 3, Dinophyta – 4, Rhodophyta – 8 and Chlorophyta – 75. Diatoms, cyanobacteria and chlorophytes form the basis of the species diversity (> 90%) in all studied rivers. The predominance of these groups reflects the specificity of the phytoperiphyton in the river systems of the boreal and subarctic zones. Leading families are Naviculaceae (174 species), Achnanthaceae (45), Desmidiaceae (43) and Fragilaceaceae (36). Together they cover 337 species or 65% of the total number of species found. The group of leading genera (187 species, 35%) includes Eunotia – 36 species, Achnanthes – 33, Navicula – 48, Pinnularia – 39, and Cymbella – 31 species. The heterogeneity of the climatic regime in the study area determines the simultaneous presence in the algae flora of widespread eurythermic species characteristic of the taiga zone, stenothermic rheophiles of alpine origin and the boreal complex typical of wetlands. The dominant complex is represented by a small number of species resistant to dynamic water loading. It is noted that the ecological-geographical spectra of algae are dominated by widespread oligogalobic species, acidophilic or indifferent to the pH of the medium. The relative importance of indicator species in the formation of groupings allows to refer the waters of the studied watercourses and reservoirs to the second class of purity.

On quasinormal frequencies of black hole perturbations with an external source

In the study of perturbations around black hole configurations, whether an external source can influence the perturbation behavior is an interesting topic to investigate. When the source acts as an initial pulse, it is intuitively acceptable that the existing quasinormal frequencies will remain unchanged. However, the confirmation of such an intuition is not trivial for the rotating black hole, since the eigenvalues in the radial and angular parts of the master equations are coupled. We show that for the rotating black holes, a moderate source term in the master equation in the Laplace s-domain does not modify the quasinormal modes. Furthermore, we generalize our discussions to the case where the external source serves as a driving force. Different from an initial pulse, an external source may further drive the system to experience new perturbation modes. To be specific, novel dissipative singularities might be brought into existence and enrich the pole structure. This is a physically relevant scenario, due to its possible implication in modified gravity. Our arguments are based on exploring the pole structure of the solution in the Laplace s-domain with the presence of the external source. The analytical analyses are verified numerically by solving the inhomogeneous differential equation and extracting the dominant complex frequencies by employing the Prony method.

Response of phytoplankton to heavy pollution of water bodies

Phytoplankton structure was studied in five ponds (located in the Oleksandriya Nature Park, Ukraine), which significantly differed in the level of their contamination. The concentration of ammonium (NH4+-N) in the studied water bodies was 0.02–74.00 mg l−1, of nitrite (NO2−-N) – 0.002–1.750 mg l−1, nitrate (NO3−-N) – 0.13–58.00 mg l−1, inorganic compounds of phosphorus (Pinorg) – 0.041–0.160 mg l−1, chloride (Cl−) – 35.4–560.5 mg l−1, whereas the content of organic matter (PO and DO) – 4.4–10.4 and 18.0–81.0 mg O l−1, respectively. It has been found that the response of phytoplankton to heavy pollution consisted in changes in its species richness, taxonomic structure, species composition, quantitative indices, numbers and biomass structure, dimensional structure, pigment index, dominant complex, as well as changes in its ecological spectrum. Individual divisions of algae differed in their response to heavy pollution of water bodies, which was conditioned by the specificity of algae metabolism. Bacillariophyta and Cyanoprokaryota proved to be more sensitive to contamination, whereas Chlorophyta and Euglenophyta – more tolerant. The obtained data can be used to monitor the status of water bodies and their biota and to determine the type and intensity of contamination.

DYNAMICS OF SOIL MESOFAUNA IN THE MONITORING OF FOREST ECOSYSTEMS IN THE KANSK FOREST-STEPPE

The study revealed that the population of pedobionts of the studied biotopes includes representatives of two types (Annelida, Arthropoda), belonging to four classes (Oligochaeta, Chilopoda, Insecta, Arachnida) and 16 families.The fauna of each site is represented by 9 families. The degree of complexity of groupings is due to the heterogeneity of stations. The biocenological similarity of the compared habitats is small (0.006-0.168), which is determined by the number of animals of the same taxonomic groups in different habitats. The dominant complex varies depending on the season and the biotope. The structure of pedocomplexes changes throughout the season: it is more diverse in mid-summer and decreases in autumn. The number and diversity of the complex of soil inhabitants depends on the season (F=3,62, P=0,033), the biotope (F= 4,03, P=0,011) and the hydrothermal habitat regime. The results obtained in the course of thе work can be a basis for the development of principles of rational nature management and environmental protection.

Phytoplankton of the cooling waterbody of the Lukoml state district power station under changing anthropogenic load

The paper presents the results of long-term research of phytoplankton of the cooling waterbody of the Lukoml state district power station (Belarus). The dynamics of abundance, biomass, community structure, and composition of the dominant phytoplankton species for the period of 1972 – 2019 were analyzed. The stages of development of the plankton algae community are determined, due to changes in the intensity and direction of anthropogenic factors. The response of phytoplankton to changes in heat load and dependence on the development of the population of Dreissena polymorpha Pallas is shown. The influence of the fish rearing complex on the developmental intensity and phytoplankton structure was revealed. Since 2004, the periods of intensive vegetation of algae alternate with a significant decrease in abundance and biomass, which indicates the unstable state of the ecosystem of the cooling waterbody. The succession of the dominant complex in 2019 was characterized by the loss of the species Aphanizomenon flos-aquae Ralfs ex Bornet & Flahault (family Nostocaceae) and the inclusion of the species Planktothrix agardhii (Gomont) Anagnostidis & Komárek (family Oscillatoriaceae).