The Sambia Peninsula (Kaliningrad region) is historically well known for its amber mining. The 2019 year was the last year of direct overburden disposal into the Baltic Sea as a part of technological amber mining process. The extremely high-suspended particulate matter concentrations during that disposal were recorded immediately after the discharge of significant volumes of pulp and reached 200 mg/L. The impact of pulp discharge had sequentially suppressed plankton communities development due to the high content of suspended solids and afterwards stimulated plankton development due to the glauconite infusion. Cladocera were the most sensitive group to the effects of suspended matter. According to the preliminary forecast, when the pulp discharge stops, the restoration of plankton communities may take from 1 to 2 seasons to 1 year for different groups. This is due to the timing of the removal of fine suspended particulate matter from sediments and the possibility of secondary entry during resuspension.

The article presents a comparative analysis of the use of direct search algorithms to perform automatic tuning and assessment of parameter values for two models of nonstratified aquatic ecosystems: the Neva Bay (NB) and the Vistula Lagoon (VL) of the Baltic Sea. Both models are built on the same methodological principles, but they have different structures, different numbers of model variables and empirical parameters. For the VL ecosystem, the biohydrochemical block consists of two parts: the «Plankton block» and the «Benthos» block. Modeling of the nutrients transformation processes in the lagoon was carried out jointly for the aquatic environment and the upper (active) layer of bottom sediments. The NB ecosystem model uses the «Plankton block», and all processes are described only for the aquatic environment. Modeling enables to quantitatively investigate the mechanisms of biohydrochemical transformation processes: compounds of C, N, P and Si in the ecosystem of the VL; N and P compounds in the NB ecosystem. Both models provide the means to study the features of spatiotemporal dynamics of oxygen dissolved in water. The NB ecosystem model contains 58 empirical parameters, while the VL ecosystem model contains 330 ones. The Theil criterion was used as a criterion for the models adequacy. The optimization problem is solved due to the two-stage computer-aided direct search algorithm. A random search algorithm was used at the first stage. At the second stage, a local search is performed using the modified Nelder-Mead simplex method. The used algorithms proved to be effective. They ensure reliability and computational convergence of the obtained calculation results. The article shows that interannual differences in parameter values are statistically significant for a number of parameters of the models under consideration. The models sensitivity to changes in parameters values was assessed.

The structure and dynamics of plankton communities in the coastal zone of the Curonian Lagoon of the Baltic Sea from January to December 2017–2021 has been studied. It was found that, at the coastal shallow littoral station surrounded by macrophytes, the species diversity was higher and the quantitative characteristics of phytoplankton and zooplankton were lower in all seasons and years of the study than at the deeper coastal station located behind the macrophyte belt. The exception was the period when, as a result of surge events, the phytoplankton biomass in the coastal littoral in October–November 2018 increased to 326–627 g/m3. Every year, Cyanobacteria “blooms” with different intensities and durations were observed at the Lagoon. The abundance of cells of potentially toxic Сyanobacteria exceeded the World Health Organization standard, as a rule, in summer months at a deepwater coastal station, especially in 2017–2018. This had a negative impact on the state of the entire ecosystem, primarily on zooplankton organisms, in which communities the proportion of dead individuals increased. Water during the period of Cyanobacterial blooms in summer and autumn 2017–2018 also had an acute toxic effect on planktonic test organisms.

В ходе гидробиологических исследований четырех малых озер Ярославской области в 2013–2015 и в 2018 гг. в фитопланктоне было выявлено 92 таксона цианобактерий и водорослей, в зоопланктоне – 76 видов планктонных животных, в макрозообентосе – 26 низших определяемых таксонов. Оз. Рюмниково по показателям фитопланктона и зоопланктона имело наиболее низкий трофический статус (мезотрофный), в нем отмечено максимальное разнообразие и количественное развитие макрозообентоса. Озера Вашутинское, Чашницкое и Заозерье по показателям фитопланктона и зоопланктона оценены как эвтрофные, а разнообразие и количественное развитие макрозообентоса в них было на низком уровне, в том числе в связи с влиянием «цветения» воды и накопления сероводорода. In total, 92 taxa of cyanobacteria and phytoplankton algae, 76 zooplankton species, and 26 lower definable taxa of macrozoobenthos were registered during hydrobiological studies at four small lakes of the Yaroslavl Oblast in 2013–2015 and 2018. According to indicators of phytoplankton and zooplankton, Lake Ryumnikovo had the lowest trophic status (mesotrophic), but both the maximum diversity and abundance of macrozoobenthos. Lakes Vashutinskoe, Chashnitskoe and Zaozer'e were eutrophic, the macrozoobenthos diversity and abundance there were low, partly due to the water bloom effect and hydrogen sulfide accumulation.

The patterns of changes in the composition and quantity of zooplankton and concentration of chlorophyll a in the estuary of the Pregolya River and adjacent waters of the Baltic Sea are considered depending on hydrological and meteorological conditions in 2021–2022. Three zones of the estuary were identified: estuarine, mixing, and marine. In the water mixing zone, there are salinity gradients, the position of which is influenced by wind forcing and river discharge. The largest concentration of chlorophyll a was noted in the estuarine zone and at the boundary of the water mixing zone, where the flow of nutrients from the drainage area is most noticeable. The removal of water from the lagoon affects the concentration of chlorophyll a and the composition of zooplankton. The estuarine zone is characterized by the highest level of eutrophication, where it approaches the threshold of hypertrophy; in the marine zone, the concentrations of chlorophyll a corresponded to eutrophic water. Depending on the inflow–outflow phenomena, the proportion of zooplankton species differs in relation to changes in salinity, and there is a sharp increase in deaths of organisms of species not adapted to a given salinity.

Original data on Cladocera fauna in water bodies and watercourses of mire ecosystems have been obtained for the first time in Kaliningrad oblast during the study conducted in large raised bogs (Zehlau and Bolshoye) and drainage canals of six peatlands affected by peat extraction. In the studied wetland ecosystems, 41 species of Cladocera are recorded in total, including a number of rare and vulnerable taxa ( Flavalona rustica, Scapholeberis microcephala, Streblocerus serricaudatus, and Holopedium gibberum ). The four species of Cladocera are new for Kaliningrad oblast. Cladocera plays a key role in the studied bog pools and waterlogged habitats in peatlands as a key group of organisms that forms here a significant part of the zooplankton biomass due to the abundance and intensive production in the water bodies. The secondary filter feeders and predators are the most abundant in bog ecosystems. The cladoceran fauna in the intact bog ecosystems, especially the Zehlau raised bog, is the most diverse and unique. Nevertheless, the cladoceran assemblages in the disturbed ecosystems of drainage canals retain certain features of the natural water bodies. The latter fact is important in the applied respect, making it possible to consider these canals refugia that have potentials for the natural restoration of the cladoceran fauna during the peatland rewetting program on the Carbon Supersite in the Kaliningrad region.

During the growing season of 2022, the studies were carried out in the water area of the Bratsk Reservoir (the Angara River) and in the near-dam site of the Bratsk high-level hydroelectric power station. The ecological effects of the hydroelectric dam on the zooplankton in the regulated section of the river were studied and the impact of the zooplankton downstream drift on the feeding conditions of the fish in the Bratsk Reservoir was assessed. It is established that the water column stratification is a significant factor in the ecological differentiation of plankton communities in the upper reaches of the hydroelectric power station. Unlike the warmed-up layer of the epilimnion, a specific, poor in species, low-abundant and low-productive plankton develops in the cold-water hypolimnion, which enters the dam intakes. A rigorous analysis does not reveal a transformation of the community composition, a statistically significant decrease in abundance and productivity, increased mortality of invertebrates during their passage through the dam, deterioration of the water ecological quality in the lower reaches of the hydroelectric power station. Both live and dead zooplankton drifting downstream from the reservoir makes up a significant proportion of the diet of fish, which during the feeding period come as close as possible to the hydroelectric power station and form aggregations exceeding those in the water area of the Bratsk Reservoir in density. The data obtained testify to the effective adaptation of lake-river planktocenosis to the specific natural and technogenic mode of operation of a large hydraulic structure. The local impact of the Bratsk hydroelectric power station has no ecologically significant negative effect on the plankton of the Bratsk Reservoir and the Angara River ecosystems and has a positive effect on the fish population in the lower reaches through the enrichment of its forage base.

When studying the ecological effects of the influence of a hydroelectric power station (HPS) dam on the zooplankton of the regulated section of the Angara River and the effect of the zooplankton downstream drift on the feeding conditions of fish of the Bratsk Reservoir during the vegetation period of 2022, it has been established that water column stratification is a significant factor in the ecological differentiation of plankton communities from the upper reaches of the Bratsk HPS. Relative to the heated epilimnion layer, a specific, poor in species, low-abundant and low-productive plankton, entering the dam water intakes, deve-lops in the cold-water hypolimnion. A rigorous analysis revealed no transformation in the composition of communities, a statistically significant decrease in abundance and productivity, and an increased mortality of invertebrates during the transition through the dam, as well as a deterioration in the ecological quality of water in the lower reaches of the HPS. Zooplankton (both alive and dead) drifting downstream from the re-servoir constitute a significant portion of the diet of fish, which get as close as possible to the HPS during feeding and form clusters that are denser than those in the water area of the Bratsk Reservoir. The data indicate the efficient adaptation of the lake–river planktocenosis to a specific natural and technogenic mode of operation of a large hydraulic structure. Locally, the Bratsk HPS has no ecologically significant negative effect on the plankton of the Bratsk Reservoir and Angara River and it has a positive effect on the fish population of the lower reaches through the enrichment of its forage base.

During the expeditions in July 2018 and 2019 data were obtained on the state of summer plankton and benthos over the entire Russian water area in the southeastern part of the Baltic Sea. The highest abundance of phytoplankton (in terms of chlorophyll “a”) is typical for the coastal region, where it reaches the eutrophic state, and decreases in the seaward zone to the mesotrophic state. Brackish water conditions determined a rather small number of species of zooplankton (36 taxa) and zoobenthos (40 taxa), including invading species (4 in zooplankton and 6 in benthos). Copepoda dominated in zooplankton in the deep-water zone, while the proportion of Cladocera and Rotifera increased in the coastal zone. The abundance and biomass of zooplankton corresponded to the maximum level observed in recent years in the SouthEastern Baltic. Zooplankton was more abundant from the coast to depths of 40 m, as a result, the best feeding conditions for planktophagous fish extended at this area. In benthos, Polychaeta and Bivalvia dominated in abundance, and Bivalvia dominated in biomass. The hydrological conditions in the Russian zone determine the development of zoobenthos in two regions separated by the Gdansk depression, which is characterized by benthic “desert” conditions. The largest region extends from the coast to depths of 70–80 m, and the second – in the deep northwestern part and is confined to the Gdansk-Gotland Sill. High abundance and biomass of zoobenthos are characteristic of the Gdansk basin down to depths of 60 m, where favorable conditions are formed for benthophage fish. The species composition and abundance of zoobenthos on the Gdansk-Gotland Sill much lower and is determined by the presence of North Sea waters inflows, in particular, in 2019 there was an increase in the abundance and distribution of benthos as a result of the inflow of North Sea waters.

In this work, potential (by the fluorescence method) and realized (by the radiocarbon method) phytoplankton primary production and the production of heterotrophic bacteria were determined in the euphotic zone of the seaward part of the Gdansk Bay of the Baltic Sea in summer and autumn. The maximum quantum efficiency of photosystem II of phytoplankton (Fv/Fm) varied significantly in depth in June (0.33–0.59), but was uniformly very high in October (0.68–0.71), which indicates a potentially more active state of early autumn phytoplankton. Integral primary production in October was almost two times higher than in June (633 and 375 mg C/m2 per day, respectively), while bacterial production was one-and-a-half times lower (239 and 371 mg C/m2 per day, respectively). In the upper tenth layer of the water column, autotrophic production (phytoplankton) only slightly exceeded heterotrophic (bacterial) production in June (63

Various water bodies of the Upper Volga River (Yaroslavl oblast, Russia) and the lower course of the Sura River (Middle Volga) are found to be inhabited by closely related rotifer species: native for both studied regions K. longispina and alien K. bostoniensis . Both species occur all year round; however their highest abundance is detected in spring or autumn. Alien rotifer K. bostoniensis has been found not only simultaneously with indigenous rotifer species but also separately, in more shallow water bodies. Alien species is more tolerant to bathymetry, basin form, transparency, and the trophic state of the water body. Probably, these features facilitate wider distribution of K. bostoniensis in the Sura basin water bodies compared to indigenous species. Alien K. bostoniensis spread relatively quickly in the Sura basin without affecting closely related indigenous species, to which it is not a competitor.

The species composition, abundance and biomass, trophic relationships of phytoplankton and zooplankton, as well as the proportion of dead individuals in zooplankton were studied in the water system "Pregolya River – Kaliningrad Sea Channel (KSC) – Vistula Lagoon – Baltic Sea" in July, August and October 2021. In total 173 taxa of phytoplankton and 73 taxa of zooplankton were found during period of investigation. The maximal species diversity was observed in the summer period, in autumn it was decreasing. The maximum number of taxa for both phyto- and zooplankton was found in the Vistula Lagoon and in the KSC, the minimum – in the Baltic Sea. In summer the 3 communities in phytoplankton, 4 in zooplankton, in autumn – 3 communities in both phyto- and zooplankton were found. The plankton communities were confined to water areas with different salinity: The Pregolya River, the KSC and the Vistula Lagoon, the Baltic Sea. The dominant complex of species at the stations differed; species of a predominantly freshwater complex were noted in the Pregolya River, brackish-water species were found in the Vistula Lagoon, and a marine complex of species was identified at the stations of the sea strait and in the Baltic Sea. More abundant plankton communities both in summer and autumn were in the KSC and the Vistula Lagoon (phytoplankton biomass varied from 1.19 g/m3 to 11.89 g/m3; zooplankton biomass varied from 305 mg/m3 to 1801 mg/m3). In this area the most optimal conditions for the development of plankton were formed such as an increased nutrient content and maximum water heating. Plankton communities both in the Pregolya River and in the Baltic Sea in summer and autumn were less abundant (phytoplankton biomass varied from 0.16 g/m3 to 2.50 g/m3; zooplankton biomass varied from 34 mg/m3 to 468 mg/m3). The most intense trophic relationships in the plankton community in the summer in the Baltic Sea, optimal – in the KSC and in the Vistula Lagoon were formed. The proportion of dead individuals in the zooplankton of the studied system in both seasons was maximal in the areas, which had the critical salinity for hydrobionts and high turbulence conditions such as KSC, the Sea strait and at the exit from Sea strait.

In 2021, Acanthocyclops trajani Mirabdullayev et Defaye, 2002, was first recorded in the Vistula Lagoon of the Baltic Sea. This species quickly spread throughout the water area of the Lagoon. In summer, A. trajani reached its maximum development (up to 92 thous. ind./m 3 , 2.4 g/m 3 ); it was a dominant, forming a particularly high proportion of zooplankton in the most polluted, desalinated, and eutrophicated eastern part of the Vistula Lagoon. As a result of predatory feeding, A. trajani exerted significant pressure on the planktonic communities of the lagoon; its diet in August exceeded the production of nonpredatory zooplankton. The pressure on zooplankton increased even more due to the mass development of Cercopagis pengoi (Ostroumov, 1891), with which the new species entered into competitive relationships. The main reasons for the successful naturalization of A. trajani in the Vistula Lagoon, apparently, include some features of its biology, the structure of the plankton community with the presence of unoccupied trophic niches, the continued eutrophication of this waterbody, decreasing pressure of the invasive mollusk Rangia cuneata (G.B. Sowerby, 1831), and the local climate warming noted in recent decades.

In lakes of the Upper Volga (Yaroslavl district) and in the lower course of the Sura River (Middle Volga), closely related rotifers - common for both studied regions native K. longispina and alien K. bostoniensis - were found. Both species occur all year round and more frequently in spring or autumn, when they are the most abundant. Alien rotifer K. bostoniensis occurred not only simultaneously with indigenous species, but also separately, in more shallow waterbodies. Alien species is more tolerate to bathymetry, basin form, transparency and the trophy state of the waterbody. This likely facilitates wider distribution of the K. bostoniensis in the Sura basin waterbodies compared to indigenous species. Alien species K. bostoniensis spread relatively quickly in the Sura basin without any harm to closely related indigenous species, to which it is not a competitor.

УЧАСТЬ О. ПАЩЕНКО У РОЗБУДОВІ НАЦІОНАЛЬНОЇ ШКОЛИ НА ПОДІЛЛІ В ДОБУ

The seasonal dynamics of production processes in the Baltic Sea are poorly studied. The aim of our research was to study the seasonal features of primary productivity (including the balance with bacterial production) and its redistribution in plankton in the southeastern part of the Baltic Sea in different seasons. More than 70% of primary production is formed in the 0–10 m layer (74–97% of the PP in the euphotic layer). In the same layer, PP accounted for almost 100% of the sum of primary and bacterial production in April and October, and almost 60% in June. Photosynthetic efficiency (PP/rETR) increased in June and October, demonstrating an increase in phytoplankton utilization of absorbed light energy. The depth-integrated values of PP, Chl a, bacterial, and phytoplankton biomasses were maximal in October. The maximum values of zooplankton biomass were determined in June, and they were significantly (5–14 times) higher than in other seasons. The maximum values of bacterial production were also in June.

Two closely related, difficult to diagnose calanoid copepod species, Eudiaptomus transylvanicus (Daday, 1891) and E. vulgaris (Schmeil, 1898), were studied based on the new material from the Sura River floodplain (the Middle Volga region, European Russia). The redescriptions and illustrations of two species are provided. The main diagnostic differences between these species are refined. New characters useful in the identification of E. transylvanicus are proposed. The data on distribution and habitats of the two species are reviewed and briefly analysed.

ПЕДАГОГІЧНА СПАДЩИНА ОЛІМПІАДИ ПАЩЕНКО У ФОНДАХ НАУКОВОГО АРХІВУ ШЕВЧЕНКІВСЬКОГО НАЦІОНАЛЬНОГО ЗАПОВІДНИКА Анотація.У статті аналізується особовий фонд О. М. Пащенко, який зберігається у Науковому архіві Шевченківського національного заповідника.Для досягнення мети дослідження та реалізації окреслених завдань авторка базувалася на фундаментальних принципах історизму, об'єктивності та системності, а також послуговувалася історико-педагогічними методами, з-поміж яких варто виділити метод аналізу літературних джерел, історикоретроспективний, що дозволяє впорядкувати та систематизувати життєві віхи О. Пащенко та історико-структурний. Подано історію листування просвітницької діячки із співробітницею Канівського музею «Могила Т. Г. Шевченка» В. Я. Кривицькою, завдяки котрій вдалося зберегти інтелектуальну спадщину О. Пащенко.З'ясовано, що остання у своїй найбільшій повноті зберігається у двох архівних зібраннях -Центральному державному архіві-музеї літератури і мистецтва України та Науковому архіві Шевченківського національного заповідника.У структурі Шевченківського меморіального комплексу сформовано особовий фонд О. Пащенко, який відноситься до категорії народної шевченкіани.Його наповнюють всього лише вісім справ, але наразі тут зібрано практично усю шевченкіану педагога.Охарактеризовано вміст справ, що зберігаються в Науковому архіві.Наголошено на унікальних документах О. Пащенко, які віддзеркалюють її життєві етапи.До таких відноситься особовий лист з обліку кадрів та особисті фото громадської діячки.Частково у фонді Наукового архіву представлена епістолярна спадщина

An increase in the level of ROS during the prenatal period, which is associated with active differentiation of cells, leads to the formation of dose-dependent teratogenic effects. The aim of this study was to determine the relationship between the duration of stress experienced by pregnant female rats in the third trimester with the degree of shift of free radical homeostasis in blood plasma and at different levels of the central nervous system. We analyzed changes in the level of activity of superoxide dismutase, changes in the products of lipid peroxidation and changes in oxidative modification of proteins in homogenates of the cerebral cortex, hypothalamus, cerebellum, and spinal cord of prenatally stressed sexually mature male outbred white rats. To this aim, their dams from 16 to 19 days of pregnancy were exposed daily to immobilization stress in plastic cases for one or three hours. Females of the control groups were kept in standard vivarium conditions with free access to food and water. Prenatal stress influenced the free radical homeostasis of all the CNS regions studied in 90-day-old male rats. More significant effects were observed after 3 hours of immobilization. The offspring of stressed mothers were characterized by more pronounced shifts in free radical balance. As a result of one-hour of daily immobilization from 16 to 19 days of pregnancy, we observed an increase in the indices of oxidative modification of the protein and lipid components in the mature offspring of stressed mothers, while the consequences of three-hour-long prenatal immobilization, on the contrary, are characterized by a decrease in the studied indices of free radical oxidation products and an increase in SOD activity. Regardless of the duration of exposure, the most pronounced shifts in the studied parameters of free radical homeostasis were in the hypothalamic region.

Abstract Functional traits are becoming more common in the analysis of marine zooplankton community dynamics associated with environmental change. We used zooplankton groups with common functional properties to assess long‐term trends in the zooplankton caused by certain environmental conditions in a highly eutrophicated gulf. Time series of zooplankton traits have been collected since the 1960s in the Gulf of Riga, Baltic Sea, and were analyzed using a combination of multivariate methods (principal coordinate analysis) and generalized additive models. One of the most significant changes was the considerable increase in the amount of the zooplankton functional groups (FGR) in coastal springtime communities, and dominance shifts from more complex to simpler organism groups—cladocerans and rotifers. The results also show that functional trait organism complexity (body size) decreased considerably due to cladoceran and rotifer increase following elevated water temperature. Salinity and oxygen had negligible effects on the zooplankton community.