A study of the levels of persistent organochlorine pesticides (OCPs) in marine mammals of the Black Sea in 2018–2022 revealed a statistically significant relationship of the accumulation levels with the sex of the animals (males were more contaminated than females) and with the age group (adults and adolescents were more contaminated than calves and newborns). The location of tissue sampling for analysis was also an important factor: OCPs accumulated more in dorsal than in caudal blubber. In blubber of Black Sea harbor porpoises and common dolphins, the mean concentrations of OCPs decreased in the order p, p'-DDE > β-HCH > p, p'-DDD > p, p'-DDT; in the common bottlenose dolphin, they decreased in the order p, p'-DDE > p, p'-DDD > β-HCH > p, p'-DDT. The most widespread and highly concentrated metabolite was found to be p, p'-DDE. The concentration of p, p'-DDD was markedly lower; significant tissue concentrations of p, p'-DDT were observed much less frequently than all other metabolites and were among the lowest of all metabolites. Based on an analysis of variations in the mean concentrations of the sum of DDT metabolites in Black Sea harbor porpoise tissues, as reported in literature sources, we can claim that there is currently a significant decrease in the concentrations of these toxicants.

Accumulation of persistent organochlorine pesticides (OCP) in fat tissue was examined for the mammals found released ashore along the Crimean coast of the Black Sea in 2018–2022. This group of animals is positioned at the top of food chain in the local marine ecosystem. Statistically significant dependence of the accumulation on sex (males are more contaminated than females) and age (adults and juveniles are more contaminated than calves and neonates) is found. Besides, the pesticides concentration in fat from dorsal tissue is generally higher than in fat from caudal stem, but the difference is not significant. In the tissue of harbor porpoises and common dolphins, the mean OCP concentration decreased in the order: p,p′-DDE > β-HCH > p,p′-DDD > p,p′-DDT, whereas bottlenose dolphins had the order: p,p′-DDE > p,p′-DDD > β-HCH > p,p′-DDT. The most common metabolites were DDE, and their accumulation was the highest. The concentration of DDD was considerably lower, and significant accumulation of DDT was observed rarely, so the mean concentration of these group of metabolites was the lowest.

Background. 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. Relevance. 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. Methods. 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. Results. 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. Conclusions. 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.

The main sources of pollutants entering the Don R. ecosystem in its lower reaches are discussed. The principal sources are navigation, construction of new berths, dredging operations, and transshipment. At the economic revival, the level of anthropogenic load increases every year, producing an adverse effect on the ecosystem. Data of observations carried out in the recent 5 years and focused on the pollution level of water and bottom sediments by oil products, stable organochlorine pesticides, congeners of polychlorinated biphenyls, heavy metals (mercury, lead, cadmium, copper, iron, zinc, chromium, nickel, and manganese), and arsenic. The stable dynamics of accumulation of some pollutants in bottom sediments is demonstrated. Some hazardous toxicants were found to accumulate in the tissues of commercial fish in the Don. The pollution of water and bottom sediments was evaluated in accordance with the Russian and regional standards and the accumulation of toxicants in commercial fishes was evaluated in accordance with the Technical Regulation of the Customs Union.

This work presents the data on the content of cadmium and arsenic in the viscera (visceral mass) of the veined rapa whelk Rapana venosa caught in the Azov Sea (Kerch Strait) and the Black Sea (Feodosia Gulf). In the viscera of the individuals from the Azov Sea, cadmium content was 8.6 mg/kg, and for the individuals from the Black Sea, this value was 3.5, with the allowable level 2.0 mg/kg as stipulated by TR CU 021/2011. Cadmium content in various internal organs of the investigated veined rapa whelk individuals varied. The highest content of cadmium (48 mg/kg) was recorded in the kidney of the individuals caught in the Azov Sea; cadmium content in the digestive gland also exceeded the allowable level. Arsenic content in the viscera of the individuals from the Azov Sea exceeded the allowable level by 7.8 %; this value was significantly lower for the Black Sea (0.1 mg/kg, while the established norm is 5.0 mg/kg). In several organs of the individuals from the Azov Sea (namely, the kidney, ovaries/testes, and digestive gland), arsenic content was within the normal values established by the regulations. The product derived from Proceedings of AzNIIRKH. Vol. 3, 2021

Ихтиофауна морских и континентальных водоемов

. Crayfish is a well-established fishing target in the basin of the Sal River within the Rostov Region. The climate change causing unstable hydrological conditions, as well as the extensive anthropogenic activity have a significant impact on aquatic biological resources. This work was aimed at the investigation of the status of the water bodies and exploitable biological resources (crayfish) in the water bodies of the Sal River Basin, with the anthropogenic pressure and climate changes taken into account. A retrospective analysis of the following parameters has been carried out: hydrological regime of the Sal River Basin since 1937, of the habitat conditions and status of the crayfish population (2012–2021), and the status of its feeding resources (2000–2013) in the context of anthropogenic activities and climate change. It has been found out that the hydrological regime of the water-deficient basin of the Sal River since the mid-1970s has been characterized by a decreased runoff during the spring flood and an increased runoff during the winter and summer–autumn low water period due to air temperature increase in the cold season. Due to the decrease in the water content of the Sal River Basin, the stream water supply lessened and the content of sulfates, chlorides and total dissolved solids in water increased, which resulted in the change of the water type from the hydrocarbonate to the sulfate one. These changes in the concentrations and ratios of salt-forming ions have been also caused by decreased precipitation and an increased feed of ground-and underground waters to the rivers of this basin . The priority toxicants and active ingredients of the pesticides of modern classes found in the water and bottom sediments of the Sal River did not affect the growth and reproduction of the crayfish . Commercial productivity of crayfish stock has shown a trend toward decrease, which resulted from the changes in some observed climate parameters (an increase in air temperature, a decrease in water content in the Sal River Basin), as well as from the increase in total dissolved solids in the water. However, the hydrochemical regime remains to be relatively favorable for life sustenance of the bottom species of aquatic animals, and the anthropogenic pollution of the ecosystem with priority toxicants is low, which makes it possible for the population to maintain stable length composition and similar quantitative values for different length classes of crayfish, as well as its reproduction capacity.

. The results of investigation of the pollution of the water and bottom sediments of the Caucasian Shelf in the Black Sea by heavy metals (copper, zinc, lead, cadmium, mercury) and arsenic, as well as their content in the Black Sea turbot Scophthalmus maeoticus (Pallas, 1814) are presented for 1995–2020. In the water and turbot, the determination of Zn, Cu, Pb, As, and Cd has been conducted using the method of atomic absorption with electrothermal atomization; mercury in all components of the ecosystems was measured using the method of atomic absorption with “cold steam”; in the bottom sediments, the content of Zn, Cu, Pb and As was identified using X-ray fluorescence method. In 1995–2020, in some water samples, the concentrations of zinc, copper and mercury exceeded the maximum permissible level established for the water bodies of fisheries importance, while the lead and cadmium were below it. The arsenic content during the entire observation period was extremely low. A noticeable decrease in the concentrations of zinc, lead and copper in the shelf waters of the Black Sea in the present period as compared with the years of the greatest pollution (1995–2002) was recorded. In the bottom sediments, the content of lead, zinc and mercury exceeded their content in the earth's crust for several years; for arsenic, the excess was recorded throughout the entire observation period. This mostly results from the peculiarities of the granulometric composition of the shelf bottom and, to a much lesser extent, from anthropogenic influence. The differences in the bioaccumulation of heavy metals and arsenic in the organs of the Black Sea turbot are shown. Out of the identified elements, only lead, mercury and arsenic in isolated cases exceeded the permissible level in the organs of the turbot in some years.

The monitoring results for the oil pollution of the Azov Sea water in the summer and autumn seasons of 2018–2020 are presented. The identified concentrations of petroleum products are given based on the total content of the main petroleum components: hydrocarbons, resins, and asphaltenes. The concentrations of petroleum products in the water ranged from <0.02 to 0.85 mg/dm3 in the summer season, and from <0.02 to 0.11 mg/dm3 in the autumn season. In some years, the weighted average values of the content of petroleum products in water exceeded the maximum allowable level: by 2.4 times in the summer season, and by 1.2 times in autumn. Based on the averaged data for the investigated period, the most severe water pollution was recorded in the central area of the Taganrog Bay and the sea itself. The highest influx of petroleum products occurs to the eastern parts of the Taganrog Bay and the sea in the autumn season, and to the southern part of the sea in summer. Along with the petroleum products identified in water, the highest content of petroleum hydrocarbons in the organs and tissues of the investigated fish was recorded in the roach, captured in the Taganrog Bay in the summer and autumn seasons of 2018. In other examined pelagic fish species of the Azov Sea (anchovy, Black Sea sprat, zander), content of petroleum products ranged at the level of determination limit.

The results of studies of oil pollution (by the sum of hydrocarbons and resinous substances) of water and bottom sediments in the northeast Black Sea in spring and autumn are presented. It is revealed that the mean oil pollution of the sea water has decreased in comparison with the data of 2001–2010, but remains quite high in some areas. The most polluted regions include the Kerch prestrait zone and the sea area between the cities of Anapa and Gelendzhik, where n-alkanes are dominated by oil homologues. The pollution of bottom sediments in the coastal sea area is higher in the period of 2016–2020 as compared to 2001–2010. Terrigenous hydrocarbons are present in bottom sediments along with petroleum hydrocarbons. Pollution of bottom sediments is increased in the areas of Abrau-Dyurso, Yuzhnaya Ozereevka, and Arkhipo-Osipovka. Taking into account the particle-size composition (according to the multiplicity of the mean typical concentration), bottom sediments of the Kerch prestrait zone are also assigned to the areas of increased pollution.

The results of content estimation of 8-e most common toxic heavy metals in the water column of the North-Eastern Black Sea in 2000-2019 are presented. Annual ranges for the content of individual heavy metals in the water column are given. Identified values have been compared with the pollution levels for the water bodies of fisheries importance as they are defined in the relevant normative and regulatory framework. Cases of exceedance of maximum permissible concentrations of copper, mercury, zinc, manganese, and iron have been recorded at all sampling depths in various seasons and years. The link to the coastline was carried out, the most problematic areas in terms of anthropogenic load were identified. A brief description of each of the metals under consideration is given. The quantitative characteristic of the increased concentrations of certain heavy metals is presented in terms of the MPC multiplicity. Seasonal dynamics of the content of particular metals in sea water during the entire course of the investigation (2000-2019) is shown. Trends and patterns in variations of their concentrations at the present time are assessed. Possible influence of increased content of the aforementioned elements on comfort the habitat of aquatic living organisms is considered.

Purpose. The study is aimed at investigating metal accumulation in the 0–2 cm layer of the bottom sediments of the Black Sea northwestern shelf over 2000–2020, and at identifying the sea bottom areas subjected to the increased anthropogenic load through comprehensive assessment of the degree of their pollution taking into account their granulometric composition. Methods and Results. The bottom sediments were sampled annually from the 0–2 cm depth at the same stations. The detected metal concentrations were compared with their content in the Earth crust and the background values. The dynamics and trends of the individual metals’ content in the shelf bottom sediments were assessed for the whole period of observations. The notion of the average characteristic concentration of an element is introduced; the procedure for its calculation is represented. The pollution of bottom sediments was analyzed with the regard for the element average characteristic concentration in the bottom sediments of various granulometric types. Increase in the average content of lead, zinc and chromium was revealed from the beginning of the observation period to 2020. The seasonal dynamics of these elements was found in the whole water area under study (as well as the iron content at some areas). Conclusions. Multiple cases of the lead, manganese and chrome concentrations exceeding their content in the Earth crust were recorded; as for zinc and copper, such cases were few and sporadic. The tendencies in variation of the bottom sediments content were determined: the average long-term values of the lead concentration increased by 1.2 times, those of zinc – by 1.6 times, and those of chrome – by 2 times; the concentrations of iron, manganese and copper remained essentially the same. Seasonal dynamics of the zinc, chromium, lead and iron content was shown. For a number of metals, the cases when their absolute content exceeded their average characteristic concentration in the corresponding type of the bottom sediments had been found. The regions subjected to a multifaceted anthropogenic load were identified; the areas of possible local inflow of the monitored elements were revealed. The bottom sediments sampled in 2019 were the most polluted.

This paper presents materials on the development of criteria for the typification of water bodies for the purposes of commercial aquaculture on the example of model water bodies in the Rostov Region. Altogether, 24 water bodies located in the southern and south-eastern parts of the Region have been investigated. The development of criteria for the typification of water bodies has been carried out based on hydrological and hydrochemical indicators, which were scored in 4 blocks. The total score established for the main hydrological and hydrochemical parameters can be used as a criterion for a water body being suitable for the purposes of commercial aquaculture. The dependence of suitability of the water body for fish farming on its location, the average annual flow rate of rivers or the annual precipitation–evaporation ratio according to the established scores has not been revealed. However, in the zone of very arid climate, more unusable water bodies have been identified. Since, according to the conditions of water availability, almost all water bodies should be classified as the reservoirs that are insecure for fish farming, the number of water bodies not recommended or recommended with significant restrictions amounted to only 25 % of the total. This indicates a fairly high potential for fish farming even in the arid zone of the Rostov Region. A brief hydrological and hydrochemical characterization of each investigated water body can be used to develop scientifically grounded recommendations for the organization of fish farms for the purposes of commercial aquaculture.

Содержание токсикантов в глубоководном и прибрежных районах Чёрного моря у Крымского полуострова в весенне-осенний период 2019 года Т. О. Барабашин, И. В. Кораблина, Л. Ф. Павленко, Г. В. Скрыпник

. The results of radioecological investigation of the bottom sediments in the Azov Sea are given for 2017–2019. Pollution of the Azov Sea bottom sediments during the period under study has been detected sporadically and is determined by redistribution of predominately post-Chernobyl fallout. The level of caesuim-137 pollution of the bottom sediments has been evaluated in comparison with its long-term average values. The results of monitoring of radiocaesium content in the main commercial fish species of the Azov Sea are presented for the same period. Comparison of caesium-137 content in the fish muscle tissues according to the sanitary and epidemiological regulations and standards, currently in force in the Russian Federation, is made. It is shown that the content of caesium-137 in the aquatic biological resources of the Azov Sea is much lower than the maximum permissible content of this isotope in fish and does not pose a radiation threat. For the investigated period, the state of the Azov Sea environment in terms of radiation does not give cause for concern pertaining to the accumulation of caesium-137 isotope. Radioecological monitoring of the Azov Sea area in 2017–2019 has revealed that Chernobyl trace remains the main source of radiation pollution.

. The content of nine heavy metals (Fe, Mn, Zn, Cr, Cu, Pb, Cd, Hg, Ni) and arsenic in the water and bottom sediments of the North-Eastern Black Sea at the present time (2018–2019) has been estimated, and the results of this investigation are presented. The analyses of samples, collected during the multi-purpose expeditions of the Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”) in the spring – early summer and summer – early autumn seasons, are summarized. Altogether, 204 water samples and 60 bottom sediment samples have been collected. Estimation of mass concentrations of heavy metals and arsenic has been conducted according to the methods, developed and adopted by the Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”). Pollution levels in the habitat of aquatic living resources have been assessed based on the standards for maximum allowable concentrations (MAC) of harmful substances in water bodies of fisheries importance and on the average long-term values. In some areas, subjected to the increased anthropogenic pressure, exceedance in MAC of iron, manganese, zinc, and nickel is recorded. It is shown that, at present, the revealed content of heavy metals and arsenic in the water and bottom sediments of the investigated area of the Caucasus Region of the Black Sea does not pose a threat for the aquatic living resources.

Results of long-term studies on the accumulation of organochlorine pesticides (OCP), polychlorinated biphenyls (PCB), heavy metals and arsenic in muscles, liver and gonads of the main commercial fish species of the Azov Sea (round goby Neogobius melanostomus, zander Sander lucioperca, so-iuy mullet Planiliza haematocheila, roach Rutilus heckelii, and anchovy Engraulis encrasicholus) are presented for the period from 2009 to 2018. Evaluation of OCP, PCB, heavy metals and arsenic was carried out in accordance with the techniques developed in the Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”). Out of the organochlorine pesticides under investigation, only the breakdown products of dichlorodiphenyltrichloroethane (DDT), such as dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), were found in the samples; the DDT was not detected. The content of hexachlorocyclohexane isomers (α-, γ-, β-HCH) in the total amount of OCP was either below the limit of determination, or insignificant (2–3 %). Out of congeners of polychlorinated biphenyls in the organs of the investigated fish, persistent and dangerous penta-, hexaand heptachlorobiphenyls were present in different variations, among which dioxin-like congeners were found. The concentrations of OCP and PCB found in the organs of commercial fishes did not exceed the allowable levels (AL) provided by Sanitary Rules and Norms (SanPiN). Accumulation levels of heavy metals and arsenic were low, aside from isolated cases when allowable levels were exceeded.