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  • Release of juvenile sturgeons in the Azov–Kuban region by sturgeon hatcheries of the Federal Agency for Fishery in 2016–2022

    Polin, A.A.; Shevchenko, V.N. (2023)
    Aquatic Bioresources & Environment
    By the end of the 20th and the beginning of the 21st century, artificial reproduction had taken up a key role in the sturgeon stock recruitment in the natural water bodies of the Azov–Kuban region. The major part of artificial reproduction of sturgeon species is conducted in the fish hatcheries of the Azov–Kuban region under the authority of the Federal Agency for Fishery (Rosrybolovstvo). The aim of this study was to analyze the volumes of rearing and release of juvenile sturgeons into water bodies of fisheries importance in the Azov–Kuban region by fish hatcheries subordinate to the Federal Agency for Fishery. This article is based on the data recordings of the Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”) for the time range from 2016 through 2022. The data on 4 sturgeon hatcheries (Adygea, Achuevo, Grivensk, and Temryuk) are presented and analyzed. Results. An increase in the total number of juveniles of sturgeon species released into the natural habitat has been revealed. The highest values were recorded in 2021–2022. There has also been a disproportion in the number of released juveniles belonging to different species. Each year, sterlet Acipenser ruthenus accounted for a large share of released juveniles, for which the percentage ranged from 47.6 % in 2018 to 64.4 % in 2022. In recent years, the volumes of rearing and releasing the juveniles of this species have been increasing both quantitatively and in percentage terms. This fact can be explained by the earlier maturation of sterlet breeders, shorter intervals between repeated spawning, and the resultant larger number of “active” breeders of this species in the hatcheries. From 2019 through 2022, the share of the juveniles of sturgeon species released by the hatcheries of the Federal Agency for Fishery into the Protoka River, as compared to the Kuban River, increased from 55.0±0.10 % in 2016–2018 to 68.9±0.44 % (2019–2022). It resulted from the increase in the number of the sturgeon juveniles released into this water body, and not from a redistribution of release volumes between the Kuban and Protoka Rivers. In general, the artificial reproduction of sturgeon species by the fish hatcheries of the Federal Agency for Fishery in the Azov–Kuban Basin has shown a positive dynamics. However, it has also been found necessary to increase the scale of artificial reproduction of the most commercially valuable anadromous species: Russian sturgeon Acipenser gueldenstaedtii and stellate sturgeon Acipenser stellatus.
  • Artificial reproduction of semi-anadromous fish species under different development scenarios of hydrological situation in the Azov Sea

    Mirzoyan, A.V.; Belousov, V.N.; Shevchenko, V.N.; Polin, A.A.; Rybalchenko, A.D.; Poroshina, E.A. (2023)
    Aquatic Bioresources & Environment
    Semi-anadromous fish species of the Azov Sea were the primary fishing targets before the regulation of the flow of the Don and Kuban Rivers, after the anthropogenic transformation of which artificial reproduction became the main source of recruitment for the populations of these species of aquatic biological resources. Unprecedented climate-induced reduction in the volume of freshwater runoff in 2006–2023 aggravated the deterioration of the conditions for reproduction of anadromous fish species in the aquatic areas associated with fish feeding and rearing facilities and contributed to the decline of their feeding conditions in the sea resulting from a sharp increase in salinity, which led to a reduction in their population abundance. Relevance. In the context of a record reduction in freshwater runoff and increasing salinity of the Azov Sea, the Azov Sea ichthyocenosis undergoes a fundamental restructuring, which requires making a forecast of the possible changes in the habitat of semi-anadromous fish species, as well as evaluating the prospects for artificial reproduction of zander, roach and bream for their preservation in new conditions, which, in turn, serves as the aim of this work. To predict possible changes in the hydrological regime of the Azov Sea, the expert evaluation method has been used. The expert assessment of possible scenarios of the impact exerted by the modern climate change on the habitat of the aquatic biological resources in the Azov Sea has been done with the regard to the provisions of the Climate Doctrine of the Russian Federation. Under all predicted scenarios for the period up to 2030, the salinity of the Azov Sea will exceed the values optimal for the juveniles and mature individuals of semi-anadromous fish species. Preservation of biologically valuable populations of zander and roach is possible with the continuous operation of hatcheries (spawning and rearing facilities), both in limans and on floodplain. To preserve the population and increase the stock of bream, it is necessary to restore artificial reproduction of this species. In the medium term (until 2030), only roach has a prospect for the sufficient recovery of its stocks, which could happen under the favorable hydrological scenario involving the water content increase in the basin. In all other cases, bream, zander and roach will not be in position to considerably increase their abundance.
  • Morphological characteristics and biological features of Smith's barb Puntioplites proctozystron (Bleeker, 1865) in the Mekong River Delta

    Karpova, Evgeniia; Iskiv, Aleksandra; Shavriev, Dmitry; Dinh Cu, Nguyen; Ba Hai, Truong (2023)
    Aquatic Bioresources & Environment
    Fisheries in the Mekong River are characterized by high pressure and extremely low selectivity towards fishing targets, which greatly complicates the conservation and possible restoration of the region's biodiversity. Relevance. Knowledge of fish population structure and biology is essential for fishery management and rational use of resources; however, the fisheries of the region are predominantly artisanal, for which the information on catches is scarce. This work is aimed at a study of the morphological characteristics of Smith's barb Puntioplites proctozystron (Bleeker, 1865) and the distribution of its quantitative parameters. The data have been collected from the bottom trawl catches in the Mekong River Delta that were conducted using a beam trawl in the low water and flood periods of 2018–2022. The average abundance and biomass of this species in fresh waters were 8.3±20.8 ind./ha and 114.7±229.4 g/ha, and in the estuary they were 0.6±2.7 ind./ha and 12.1±63.5 g/ha. These quantitative parameters for Smith's barb in the relatively shallow and low-flow Hau River and its estuarine channels were statistically significantly higher than in the rest of the delta estuary system (8.5±22.2 ind./ha and 110.7±248.7 g/ha as compared to 1.4±6.5 ind./ha and 25.0±90.1 g/ha). Examination of morphological characteristics showed a very low variability of traits in mature individuals; the coefficient of variation was less than 10 %. The obtained results indicate the absence of sexual dimorphism and different morphotypes in the population, provide the ground for minimum landing size recommendations, and can serve as a foundation for the further population research of this species.
  • Results of the investigation of the Azov Sea populations of sturgeon fish species as a part of monitoring the catches by stationary fishing gears along the Kuban coast

    Vasev, A.B.; Luzhnyak, V.A.; Barinova, V.V.; Vakulenko, S.O.; Belyaev, V.A.; Mirzoyan, A.V. (2023)
    Aquatic Bioresources & Environment
    After depletion of the Russian sturgeon Acipenser gueldenstaedtii Brandt & Ratzeburg, 1833 and stellate sturgeon Acipenser stellatus Pallas, 1771 stocks at the end of the 20th century, their abundance in the Azov and Black Sea Basin has been maintained through the release of the juveniles obtained by the means of artificial reproduction. Resulting from the strengthening protection of the aquatic living resources and gradually increasing number of the released juveniles, since 2014, as evidenced by the research studies, an increase in the population abundance of these fish species and their biomass is observed in the Azov Sea (from 42 t in 2015 to 998 t in 2022). Unstable state of the sturgeon populations in the coastal waters of the Azov Sea predicated the relevance of this work. Its aim was to investigate the distribution and age–length composition of the populations of the sturgeon fish species in the coastal waters of the Azov Sea. This study was based on the data on age–length composition collected over the course of the investigation of sturgeon by-catches in stationary pound nets in the coastal waters of the Azov Sea within an administrative unit Primorsko-Akhtarsky District (Yasensk and Achuevo Spits). According to its results, out of all sturgeon species, in the autumn season, the stellate sturgeon prevailed—53 %; the share of Russian sturgeon was 43 %, and for beluga sturgeon, it was 4 %. In summer, the Russian sturgeon share in the catches was 79 %, and for stellate sturgeon, it was 21 %. There have also been recorded some differences of the Russian sturgeon and stellate sturgeon length composition between the early spring and middle autumn, which can result from the fact that the sturgeon individual of greater length leave their wintering sites in the Azov Sea open waters earlier and sooner enter the coastal waters in spring. Conclusions. This study makes it possible to improve the assessment of the stock status and distribution for the sturgeon fish species in the Azov Sea.
  • Short-term forecast of the changes in the primary production of organic matter and pollution by priority toxicants in the Azov Sea

    Kosenko, Yu.V.; Korablina, I.V. (2023)
    Aquatic Bioresources & Environment
    Modern climate changes and increasing anthropogenic water withdrawal in the Azov Sea river basins have led to a reduction in freshwater runoff and a record increase in the sea salinity. Salinization of the Azov Sea leads to a transformation of the structure of biological communities and a decrease in primary productivity, which inevitably has a negative impact on fish productivity. Another important factor in the stock formation of aquatic biological resources is the quality of their habitat. Aim of this work is to make a short-term forecast of the hydrochemical foundation of biological productivity and toxicological status of the Azov Sea up to 2030. This study was based on the long-term data on the level of primary production, hydrochemical regime and accumulation of priority toxicants in the Azov Sea ecosystem. In the present period, adaptation of the Azov Sea ecosystem to increasing water salinity is manifested in a decrease in the level of primary production. In recent years, during the summer season, an unfavorable physiological state of phytoplankton has been observed due to the high content of pheophytin in the cells. In the Azov Sea, from 1986 (the peak of industrial development and anthropogenic load) up to the present, in the water, bottom sediments and muscles of commercial fish species, has been observed a decrease in the average annual concentration of the majority of monitored toxicants. Under the most likely forecasted scenario for the river flow and water salinity (14.5–16.5 ‰), a further decrease in the level of primary production is expected. It is possible that the ecosystem will adapt to the increase in water salinity; phytoplankton will be characterized by a more favorable physiological state in the summer. No deficiency of biogenic elements is predicted. If the existing anthropogenic load remains unchanged (the most likely scenario), the level of sea pollution by anthropogenic toxicants is predicted to be low, and in certain areas — Taganrog Bay, the waters of the Yeysk and Temryuk Sea Ports — it is expected to be moderate. The quality and safety of aquatic biological resources as a food product will meet regulatory requirements.
  • Possible scenarios for the formation of the continental runoff and the salinity of the Azov Sea, taking into account the current and future trends in climate change

    Zhukova, S.V.; Mirzoyan, A.V.; Shishkin, V.M.; Podmareva, T.I.; Lutynskaya, L.A.; Taradina, E.A.; Burlachko, D.S.; Karmanov, V.G. (2023)
    Aquatic Bioresources & Environment
    The ongoing climate changes have a significant impact on the formation of the habitat conditions for the aquatic biological resources of the Azov Sea. Salinity of the Azov Sea waters and continental runoff, which role in maintaining the ecological well-being of the habitat of aquatic biological resources is paramount, has underwent particularly noticeable transformations. Relevance. Assessment of the degree of influence of ongoing and expected climate changes on the formation of abiotic parameters of the marine ecosystem is a prerequisite for planning the successful development of the fisheries industry of the Azov Sea Basin. The aim of this work is to assess the current and expected changes in the hydrometeorological parameters of the Azov Sea ecosystem, as well as to identify the most probable scenarios of changes in the Azov Sea salinity depending on the annual volume of continental runoff. Methods. The study is based on the data from AzNIIRKH database for the time range 1960–2020 collected over the course of the expedition surveys examining the Azov Sea hydrological regime and the data of the reference observation network of the Russian Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet). Methods of mathematical statistics, graphoanalytical construction, mapping and analogy have been used for the data analysis. Results. This paper assesses the changes in the hydrological regime of the Azov Sea based on the annual monitoring of the habitat of aquatic biological resources. Preliminary calculations have been performed, and new data on the changes in the parameters of the sea water balance equation not covered by monitoring over the past forty-five years have been presented. The most probable formation scenarios for the continental runoff and the Azov Sea water salinity for the future up to 2030 are considered, with the observed trend of climate warming taken into account. Conclusions. Both the climatic and anthropogenic factors have contributed to considerable changes in the current hydrometeorological regime of the Azov Sea. These changes have mainly been manifested in an increase in air and water temperatures, a decrease in wind activity, and in a reduced continental runoff, in the formation of which, since 2006, a prolonged low water content cycle has been observed. The shortage of river runoff and increased water evaporation rate, along with other factors, have induced an unprecedented increase in the Azov Sea salinity, the average annual value of which in 2021 reached a record high (14.97 %). In the most probable scenario (60 %) with the continuation of the low water content period and the continental runoff into the Azov Sea of about 22 km3 in volume, the average annual salinity of the Azov Sea, including Taganrog Bay, can reach 15±0.40 ‰ with a variation range from 14.5 to 16.5 ‰ in the sea itself (excluding Taganrog Bay). 2021 can serve as an analogous year in terms of salinity formation and its spatial distribution.
  • Aquatic Bioresources & Environment. Vol. 6, issue 4

    Bragina, Tatyana; Azov-Black Sea Branch of Russian Federal Research Institute of Fisheries and Oceanography “VNIRO” (AzNIIRKH) (Azov-Black Sea Branch of Russian Federal Research Institute of Fisheries and Oceanography “VNIRO” (AzNIIRKH), 2023)
    Possible scenarios are given for the formation of the continental runoff and the salinity of the Azov Sea, taking into account the current and future trends in climate change. Short-term forecast are suggested for the changes in the primary production of organic matter and pollution by priority toxicants in the Azov Sea. Specific features of photometric determination of organic carbon in bottom sediments are presented. Exploitable resources of commercial invertebrates in the Azov Sea and the dynamics of their exploitation in 2000–2022 are considered. The Azov Sea populations of sturgeon fish species as a part of monitoring the catches by stationary fishing gears along the Kuban coast are investigated. Morphological characteristics and biological features of Smith's barb Puntioplites proctozystron (Bleeker, 1865) in the Mekong River Delta are studied. Artificial reproduction of semi-anadromous fish species under different development scenarios of hydrological situation in the Azov Sea is analysed. Release of juvenile sturgeons in the Azov–Kuban region by sturgeon hatcheries of the Federal Agency for Fishery in 2016–2022 is reported.
  • Exploitable resources of commercial invertebrates in the Azov Sea and the dynamics of their exploitation in 2000–2022

    Mirzoyan, A.V.; Saenko, E.M.; Dudkin, S.I. (2023)
    Aquatic Bioresources & Environment
    In the context of a low water conent in the Azov Sea along with an increase in its salinity and the background temperature, a decrease in the stocks of stenohaline species of bioresources and an expansion of the species composition of halotolerant species are observed; out of the latter ones, the populations of commercial invertebrates are presently characterized by a drastic increase in their stock abundance and biomass. Upon the development of an increased salinity regime of the Azov Sea, it becomes relevant to monitor the undergoing fundamental changes in the exploitable resources of commercial invertebrates. The aim of this work has been to assess the resource potential of commercial invertebrates for the period 2000–2022 and make a forecast of its dynamics under various salinity conditions of the Azov Sea up to 2030. Analytical data characterizing the status of the exploitable resources of commercial invertebrates in the Azov Sea were originally collected during expeditionary surveys in 2000–2022. To characterize the Azov Sea stocks of commercial invertebrates, standard methods of collecting and analyzing the field samples indicative of the state of their populations have been used. A retrospective analysis of the species composition of commercial invertebrates in the Azov Sea indicates an expansion of the list of commercial species, an increase in their stocks and catch volumes, as well as the potential for further additions to the list of commercial species by involving new ones, currently not targeted by fisheries. The development of the invertebrate fishery creates a crucial alternative to the deteriorated catches of commercial fish species and may facilitate the preservation of a small fishing fleet in the Azov Sea, preventing its decline. In the case if salinity remains in the 14.5–16.5 ‰ range or increases to 18.5 ‰, there will be maintained the favorable conditions for increasing the catches of molluscs (veined rapa whelk, mussels, unequal arc), crustaceans (shrimps, Gammarus, Artemia), insects (chironomids), and jellyfish.
  • Specific features of photometric determination of organic carbon in bottom sediments

    Shevtsova, E.A.; Burdina, E.I. (2023)
    Aquatic Bioresources & Environment
    Organic matter in bottom sediments originates from plants and animals as a metabolic byproduct; it determines biological productivity of a water body and physical and chemical properties of its bottom soils, enriches its aquatic environment with biogenic elements, and provides nutrients for its benthic communites, on which, in turn, feed benthophagous fish species. The most reprepresentative indicator of the organic matter in bottom sediments is organic carbon. Currently, for determination of the organic carbon directly in bottom sediments, either expensive equipment or certified methods approved for soils are used. This work presents the results of development and validation of the method for quantitative determination of organic carbon in bottom sediments. The developed modification of I.V. Tyurin’s method is based on photometric detection of trivalent chrome that is equivalent to the content of oranic carbon after oxidation of the organic matter in bottom sediments in chromosulfuric acid. Chloride interference was precluded with silver sulphate; as a reference standard, the State Standard Sample of glucose was used for the first time. This method has been tested on the bottom sediments of the Azov Sea, and the results are found to be in compliance with those obtained from the investigations conducted by the traditional Tyurin’s method with silver sulphate. This method does not require expensive equipment and is applicable for mass determination. Based on the results of this investigation, a metrological certification of the developed method has been conducted; it regulates the procedure for determination of carbon mass fractions in the bottom sediments of water bodies in the range from 0.3 to 16.0 %.
  • On the fifth anniversary of the scientific peer-reviewed journal “Aquatic Bioresources & Environment”

    Bragina, Tatyana; Mikhaylyuk, Ekaterina A.; Reshitko, E.E.; Savchuk, Elena A. (2023)
    Водные биоресурсы и среда обитания
    The scientific peer-reviewed journal “Aquatic Bioresources & Environtment” has been published since 2018 and functions as a discussion platform for researchers and practitioners of the vast fishery region (mainly the Southern Russia). In July 2023, the journal celebrated its fifth anniversary. The aim of this article is to review the notable milestones of the formation of the journal as a scientific publication from its first issue up to the present moment. Currently, the journal is included in the List of peer-reviewed scientific publications, in which the main scientific results of dissertations for the degree of Candidate of Science and for the degree of Doctor of Science should be published (List of the Higher Attestation Commission), and is abstracted in the International Information System for Aquatic Sciences and Fisheries Abstracts (ASFA) and the Scientific Electronic Library (eLIBRARY), as well as indexed in the Russian Science Citation Index (RSCI). Articles in the journal are assigned with Digital Object Identifiers (DOI), which are registered by the international agency Crossref; they are posted on the journal's website and added to RSCI and other databases.
  • Stock assessment of the marine fish species in the Black Sea (Russian waters) in 2021

    Shlyakhov, Vladislav; Piatinskii, Mikhail (2023)
    Водные биоресурсы и среда обитания
    Based on the available biological and fisheries data, stock status review for 18 units of the fish species inhabiting the Black Sea and the both Azov and Black Seas is presented. A modified version of the traditional approach to the harvest control rules for the aquatic bioresources of the Azov and Black Sea Fishery Basin is described for the case when they are assessed by the mathematical methods to estimate the current stock biomass and fishing mortality. For 11 stock units, analytical modeling including cohort, production and trend models has been applied. Based on the estimates of biomass and fishing mortality concerning biological reference points, in 2021, the status of six stock units of the marine fish species inhabiting the basin and exploited by the Russian fisheries was identified as increasing or stable (“Black Sea” stock units of the European sprat and European anchovy, “Crimean” stock unit of turbot, “Crimean and Caucasian” stock unit of red mullet, and “Black and Azov Seas” stock units of garfish and rays). Five fishery stock units (“Crimean and Caucasian” of mullets, picarel and Mediterranean horse mackerel, “Black and Azov Seas” of sand smelts, and “Caucasian” of turbot) have shown a decreasing trend in terms of abundance, and for the rest of the investigated fish stock units (“Mediterranean migrant” bluefish, Atlantic bonito and Atlantic mackerel, “Black Sea” whiting, so-iuy mullet and the other marine fish species, “Black and Azov Seas” spiny dogfish), the status has not been determined due to the absence of systematic biological and fishery data.
  • Fluctuating asymmetry of the head seismosensory canals in roach Rutilus rutilus (L.) from the middle rivers of Udmurtia with different levels of chemical pollution

    Kotegov, Boris (2023)
    Aquatic Bioresources & Environment
    In the middle rivers of the Udmurt Republic, fish were caught near the sampling stations for the state environmental monitoring. The fluctuating asymmetry (FA) of the pore number of the seismosensory canals in the dermal head bones of the roach, Rutilus rutilus (L.), which prevailed in the catches, was estimated using osteological analysis. Its indicators in the roach individuals caught in the different river sections have been collated with the values of specific combinatorial water pollution index (SCWPI) of the examined sections and with the average concentrations of some pollutants in water in late spring and early summer for the several years preceding the years of catching. A statistically significant trend for the increase in the FA variance (Sas2), calculated on the basis of the total number of pores in the head seismosensory system of the roach, with the increase in the SCWPI and the content of some anions (chlorides, nitrites, nitrates) in the river water of its habitats has been identified. The highest Sas2 was observed in the roach individuals caught in the Izh River dowstream from Izhevsk in the environment, severely polluted by municipal wastewater, while the lowest one was recorded in the Kilmez River, the least polluted by wastewaters. No significant relationships between the FA indicators in this fish species and the content of heavy metals or other pollutants in the middle rivers of Udmurtia have been revealed. These results are considered to be attributable to a decrease in stability of morphogenesis in the fish organisms that developed under non-optimal (stressful) hydrochemical conditions.
  • Characterization of the beluga breeding practices at the Don Sturgeon Hatchery

    Vorobieva, O.A.; Gorbenko, E.V.; Sergeeva, S.G.; Pavlyuk, A.A.; Khorosheltseva, V.N. (2023)
    Водные биоресурсы и среда обитания
    The study conducted in 2022 has identified a lack of consistency in the results of the beluga artificial reproduction at the Don Sturgeon Hatchery (DSH). To obtain eggs, mostly the females born in 2001–2004 were used, out of which 31 females at age 18 reached their first maturity and one female at age 21 was a repeat spawner. The majority of first-spawning females produced eggs of low quality. During incubation, there was a substantial loss of fertilized eggs, and various anomalies of embryonic development were observed, which necessitated termination of the incubation of such eggs. The yield of one-day larvae from the eggs obtained from the first-spawning females and set for incubation was low, around 12 %. One of the reasons for the increased mortality rates and development anomalies in the larvae was low quality of the oocytes in the first-spawning individuals. A second-spawning female has shown satisfactory results; the fertilization rate was in line with the standard values, and no more than 17 % of the eggs manifested embryonic anomalies during their incubation. The yield of one-day larvae was 53.3 %. In total, 799 thousand one-day beluga larvae were obtained. The analysis of the cultivation practices at the Don Sturgeon Hatchery made it possible to identify the bottleneck points and critical junctures at some stages of the biotechnological process, as well as to give recommendations on improvement of the hatchery operation. An important prerequisite for obtaining good results is the physiological adequacy of beluga females, which is based, for the most part, on the living environment and feeding quality of the breeders and their replacement in the broodstock.
  • Hydrobiological communities of the middle reaches of the Lena River

    Sidorova, Lena I.; Gorokhova, Elena S.; Kolodeznikova, Yorinda N. (2023)
    Водные биоресурсы и среда обитания
    The investigated site is located within the area of the Yakutsk Urban District and subjected to a high anthropogenic load. The construction of a bridge over the Lena River at its middle reaches is crucial for transport accessibility but will have a negative impact on aquatic bioresources and their habitat. Previously, this section of the river has not been studied, so the results will be indicative of the current state of aquatic biological resources and their habitat. This factor determined the aim of this study: the status assessment of the hydrobionts inhabiting a localized area in the middle reaches of the Lena River. The hydrochemical analysis of water samples has been carried out in the laboratory of the Republican Center for Information, Analysis and Environmental Monitoring (State Budgetary Institution “RIATSEM”); collection and laboratory processing of zooplankton and zoobenthos samples have been conducted according to generally accepted methods. The hydrochemical composition and dissolved gases of the aquatic environment in the localized section of the Middle Lena River in the vicinity of the bridge crossing are favorable for the development of organic life. Zooplankton is represented by 54 species, more than a half of which is comprised by rotifers (52 %). The average biomass of zooplankton in the spring and summer seasons was 1.135 g/m3; in the autumn and winter seasons it was 0.057 g/m3, and the average annual value was 0.238 g/m3. Crustaceans have the highest share in the biomass, and rotifers are the most abundant. Zoobenthic organisms are represented by 9 groups; oligochaetes and chironomid larvae prevail throughout the year. The average biomass of the zoobenthos in the area along the shore was 37.41 g/m2; in the auxiliary streams it was 174.84 g/m2, and in the main course it was 3.52 g/m2. Following the results of this study, the qualitative and quantitative characteristics of the invertebrates have been found to be indicative of a favorable state of their habitat.
  • Long-term variability of oceanic zooplankton biomass

    Piontkovskiy, Sergey A.; Minsky, Ivan; Мегер, Яков (2023)
    Водные биоресурсы и среда обитания
    Numerous scientific publications are dedicated to the analysis of long-term variability of zooplankton biomass in oceanic and neritic zones of the World Ocean. The number of these publications keeps growing with the availability of new data. Relevance of this research can be attributed to the crucial role of zooplankton biomass in the spatio-temporal and trophic structure of aquatic ecosystems. Interannual fluctuations of zooplankton biomass affect the catch volumes of small pelagic fish. This research is aimed at identification of statistically valid long-term trends of the World Ocean zooplankton biomass, which involves the analysis of the data from databases and published articles describing such variability. Regional and international databases (namely COPEPOD, HOT, JGOFS, ODATE and others), which are available in the form of CDs, archived materials, and online, have been used. For the time series of the biomass across 21 areas of the World Ocean (Pacific, Indian, Atlantic Oceans and internal seas), the regression analysis has been conducted, which made it possible to estimate the parameters of linear monotonic trends. Based on bivariate spatial autocorrelation functions, the areas within which the trends are statistically homogeneous have been identified. A comparative study of long-term variability of zooplankton biomass, phytoplankton biomass, primary production, and the total live biomass of the pelagic World Ocean is presented. It is shown that the spatial distribution of positive, negative and neutral trends of zooplankton biomass on the World Ocean scale is heterogeneous. The negative monotonic trends of zooplankton biomass are found to be prevailing (in 1980–2010s); the regression parameters describing them are presented.
  • Energy metabolism of Mytilus galloprovincialis under low seawater pH

    Vialova, Oksana (2023)
    Водные биоресурсы и среда обитания
    The problem of acidification of the World Ocean and predicting the consequences for its inhabitants is becoming more and more relevant every year. The effect of short-term pH fluctuations in coastal ecosystems on the physiology of calcifying organisms—bivalves—remains poorly understood. The energy metabolism of the Black Sea mussel Mytilus galloprovincialis was investigated for the marine environment in a wide pH range, from 8.2 to 6.65. Lowering the pH to 7.0–7.5 led to a 20–25 % reduction in oxygen consumption by molluscs. At lower pH (6.54–6.7), aerobic respiration sharply decreased by 85– 90 %, down to the minimum values (2.12–2.62 μgO2/g dry/h), and the organisms transitioned to anaerobic metabolism. The metabolic response of the mussels subjected to short-term pH changes (8.2→6.65→7.2) has been investigated. The oxygen consumption of molluscs exposed at the same pH of 7.2 depended on the direction of the change in pH. Thus, in the case of pH 6.65→7.2, the respiration intensity was 30 % higher compared to the values obtained under the acidification pH 8.2→7.2. The Black Sea mussel M. galloprovincialis is shown to have the capacity for survival in the marine environment characterized by the rapid fluctuations in pH that occur during the upwelling events in the coastal areas of the Black Sea.
  • Infection of cyprinid fish with larvae of human-pathogenic helminths and bacteria in the Lower Volga River Delta at the present time

    Proskurina, Viktoriya V.; Menkova, Anna V.; Voronina, Elena A; Diakova, Svetlana A.; Lakhtina, Anastasia (2023)
    Водные биоресурсы и среда обитания
    Recreational and artisanal fishing is very widespread in the Astrakhan Region; its primary targets are cyprinids, which are susceptible to epedemiological threats. Food products derived from the biological resources harvested during such fishing are not subjected to the processing in specialized facilities, and therefore, safety of the final product for its consumer cannot be ensured. In this region, the diseases, the agents of which are transmitted through fish and the products of its processing, are annually recorded among the population. Sanitary and parasitological control is one of the components in the set of measures for the prevention of these diseases. This work was aimed at evaluation of the infection level in some species of commercially valuable cyprinids in the Lower Volga River Delta with bacteria and larvae of pathogenic helminths capable of causing the development of diseases in humans. An incomplete helminthological survey of Caspian roach, common bream, white bream, crucian carp and rudd, as well as microbiological examination of their muscle tissue have been carried out in accordance with the requirements of the regulatory documents currently in force with application of methods described in State Standards. Larvae belonging to four species of human-pathogenic parasites have been recorded in the parasitic fauna of the Caspian roach, rudd, and white bream. Common bream was infected by larvae belonging to two species of such helminths. The identified larvae of pathogenic trematodes and nematodes were viable. The level of bacterial contamination of fish muscle tissues did not exceed the standard-prescribed limit, and the sanitary indicator microorganisms were absent. The results of the parasitological study indicated the need for mandatory disinfection of cyprinid fish from larvae of pathogenic helminths.
  • Qualitative and quantitative composition of hydrocarbons in bottom sediments in the Northeastern Kara Sea

    Tkachenko, Yulia S.; Elena, Tikhonova (2023)
    Водные биоресурсы и среда обитания
    The surface layer (0–5 cm) of the bottom sediments, which samples were collected during the expedition of the RV “Academician Boris Petrov” in the Northeastern Kara Sea in the summer of 2022, has been investigated. Data on the content and composition of hydrocarbons (HCs) in the bottom sediments of the investigated aquatic area have been obtained. Since oil and petroleum products are among the most common sources of pollution of the seas and oceans, it is necessary to conduct regular surveys of marine ecosystems. This work is aimed at a qualitative and quantitative assessment of HCs in the bottom sediments of the Northeastern Kara Sea and identification of their possible sources. Examination of the qualitative and quantitative composition of HCs was carried out by gas chromatography using the gas chromatograph "Crystal-5000.2" with a flame ionization detector. The quantitative determination of the total HC content was conducted by the method of absolute calibration of the FID using a mixture of HCs prepared by the gravimetric method. Chromatec Analytic 3.0 software was used to process the results. It has been found that the total amount of HCs in the bottom sediments of the Northeastern Kara Sea ranged from 25.8 to 152.4 mg/kg, being 68.21±7.76 mg/kg on average. Based on analysis of the chromatograms, the predominance of high-molecular fractions has been identified; the maximum distribution of n-alkanes was represented by homologous compounds n-C25–C29, which are the markers of allochthonous organic matter. After comparison with the calculated diagnostic indices (CPI1, CPI2, ACL, LWH/HWH, TAR, C31/C29, Paq, TMD, ΣC25–35/ΣC15–21, Pr/Ph), it was found that the increased concentrations of HCs mainly result from the natural processes and prevalence of allochthonous organic matter in bottom sediments.
  • Macrophytes of the genus Potamogeton as the bioindicators for the accumulation of heavy metals

    Куанова, Алина; Litvinova, Natalia; Ershova, Tatiana; Zaitsev, Vyacheslav; Шабоянц, Наталья (2023)
    Водные биоресурсы и среда обитания
    This work presents the investigation of the content of some heavy metals in the pondweeds of the Lower Volga River Delta within the area of Astrakhan State Biosphere Reserve. Higher aquatic plants extract chemical elements both from bottom sediments and water column. Moreover, the macrophytes, namely the representatives of Potamogeton genus, are capable of extraction and accumulation of the metals dissolved in the water, contained in the suspended colloidal particles, and present on the surface of leaves. This work is aimed at the identification of species-specific features of the typical hydatophytes (aquatic plants of Potamogeton genus) pertaining to the accumulation of heavy metals. The content of chemical elements in the investigated specimens has been identified using atomic absorption spectrometry; the results have been processed with statistical methods. It has been found that all investigated plant species accumulate iron and manganese in the highest quantities and cobalt and cadmium in the lowest. The investigated pondweed species have shown species-specific properties in the accumulation of chemical elements. Potamogeton crispus and Potamogeton lucens are found to be iron concentrating species. Potamogeton lucens also accumulates nickel, iron and manganese, and Potamogeton pectinatus accumulates chrome, cobalt and lead.
  • Trophic basis of the European anchovy stock development in the Azov Sea

    Mirzoyan, Zinaida; Надолинский, Виктор; Martynyuk, M.L.; Надолинский, Роман (2023)
    Водные биоресурсы и среда обитания
    Formation of the European anchovy Engraulis encrasicolus (Linnaeus, 1758) stocks in the Azov Sea depends on the development of zooplankton, which is the main food source for this fish species. Under the conditions of the natural flow regime of the rivers (1937–1951) and the 10.6 ‰ salinity of the sea, native zooplankton species ensured a high food supply for the anchovy, which resulted in relatively large anchovy stocks. During the Azov Sea salinization up to 12.8 ‰ that occurred in the late 60–70s of the last century, the zooplankton species composition changed. Predatory scyphoid jellyfish species—Aurelia aurita and Rhizostoma pulmo—underwent drastic increase in abundance, which led to the reduction in the summer biomass of the zooplankton almost by half. During that period, large stocks of the European anchovy developed less often. In the late 1980s, as a result of the introduction of a predatory ctenophore Mnemiopsis leidyi in the Azov Sea, the summer biomass of the zooplankton decreased further by 2–3 orders of magnitude. During the feeding season of the European anchovy, the areas with high zooplankton productivity disappeared, which resulted in the recurring low stocks of this fish species. At the end of the 1990s, a ctenophore Beroe ovata, feeding on the mnemiopsis, appeared in the Azov Sea. Its invasion led the delayed entry of the mnemiopsis into the sea, which, in turn, ensured the development of a sufficient food supply for the anchovy during its pre-spawning period. However, the main feeding season of the anchovy, just as before the arrival of B. ovata, took place under a shortage of the food supply. In the last few years, another increase in salinity to 15.0 ‰ is observed in the Azov Sea. The Black Sea jellyfishes A. aurita and R. pulmo are actively developing once again and, along with M. leidyi, provide even stronger food competition for the anchovy. During these years, only low-productive generations and low stocks of this fish species have been observed.

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