Assessment of the Soil Buffer Capacity in the Sea of Azov Basin Under Heavy Metal Pollution

Heavy metals (HM) are among the most hazardous soil pollutants. The intensity of accumulation and distribution of HM in soils directly depends on the ecological conditions of pedogenesis and its buffering properties. At the same time, a significant accumulation of HM in the soil as a result of anthropogenic impacts reduces the buffering capacity of the soil and its resistance to pollution. The purpose of this work was to assess the buffering capacity of soils to HM pollution in the Don River delta and the coast of the Taganrog Bay of the Sea of Azov undergoing the great anthropogenic impact. The buffer capacity of experimental soils was carried out using the Il’in’s method (1995), based on the calculation of the inactivation ability of soils: organic matter, clay fraction (particle size < 0.01 mm), carbonates, sesquioxides, and pH. The content of HM was compared with soil Clarke and the maximum permissible concentration of HM in soils accepted in the Russian Federation. It was found that the experimental soils could be ordered by buffer capacity value as following (in decreasing order): haplic chernozem ≥ alluvial-meadow light loamy ≥ solonchak > alluvial-meadow sandy and sandy loamy > sandy primitive soil ≥ stratified alluvial soil. Keywords: trace elements, contamination, impact territories

The Status of Crimea and the Sea of Azov as a Jurisdictional Hurdle in Ukraine v. Russia

On 21 February 2020, the arbitral tribunal constituted under Annex vii of the United Nations Convention on the Law of the Sea (unclos) in the Dispute Concerning Coastal State Rights in the Black Sea, Sea of Azov, and Kerch Strait (Ukraine v. the Russian Federation) rendered its award concerning preliminary objections. This comment focuses on the arbitral tribunal’s findings concerning Russia’s two most important and far-reaching objections, both of which concern jurisdiction ratione materiae. First, it argues that the arbitral tribunal convincingly declined jurisdiction over those of Ukraine’s claims, which would have required the arbitral tribunal to decide the dispute between Ukraine and Russia concerning sovereignty over Crimea. Second, this comment analyzes the arbitral tribunal’s conclusion that the parties’ dispute concerning the status of the Sea of Azov and Kerch Strait was not of an exclusively preliminary character and must, therefore, be reserved for the proceedings on the merits.

Assessment of infection of hamsa Engraulis encrasicolus nematode Hysterothylacium aduncum in the Sea of Azov in the summer and autumn periods 2015-2020

The dynamics of infection of anchovy Engraulis encrasicolus Linnaeus, 1758 with nematode parasite Hysterothylacium aduncum Rudolphi, 1802 in the Sea of Azov during the summer seasons of 2015 and 2017-2020 and autumn seasons of 2017-2020 is analyzed. To specify the scheme of infestation, the division of nematodes into living and degenerating ones was used. The degenerating specimens were attributed to three stages of destruction. The infection rate was estimated by using of the common parasitological indices (prevalence of infection, intensity values, abundance of larvae). Statistical analysis of data obtained in the process of the research was conducted using Spearman’s rank correlation.

State of the Fishing and the Aquaculture in the southern Seas of Russia in XXI century

The analyze of dynamic of quantity and composition of the Russian catches in the Sea of Azov, Black and Caspian Seas in the 21st century was made. It has been shown that catches decrease with a simultaneous increase in the proportion of marine fish proper. The analyze of aquaculture development in southern regions is provided and also identified the prospects for its development in the near future. Currently, there is a positive dynamics of growth in the production of commercial fish farming products. Since 2000 this parameter has decreased from 77 to 328 thousand tons in 2020. The volume of aquaculture in the southern regions of the country in 2020 amounted to more than 78 thousand tons, which is 24% of the total Russian. In Rostov and Astrakhan region, Krasnodar territory obtained 90.6% aquaculture production. The perspective ways are pasture aquaculture, ponds and industrial fish farming, recreational aquaculture, mariculture. The expansion of the species diversity of farmed fish is possible both due to the aboriginal ichthyofauna and the use of previously acclimatized species.

Biochemical and hematological parameters of the roach Rutilus rutilus heckelii (Nordmann, 1840) from the Sea of Azov stock in the spring season of 2020–2021

This work presents the results of the investigation of the physiological state of the roach Rutilus rutilus heckelii breeders from the Sea of Azov stock during the spawning period. It has been established that, in the spring season of 2020 and 2021, the content of proteins and lipids in fish tissues, as well as hematological parameters in all investigated roach specimens from different water bodies were consistent with the average long-term values. The content of proteins in the muscles and liver of roach does not differ by sex. A higher protein content in the gonads of females is characteristic of the pre-spawning period due to the process of gonad maturation. The high content of lipids in the gonads of males apparently results from the lower energy consumption for maturation of the gonads and spawning. The average concentration of sodium and potassium ions decreased in comparison with the values obtained in 2020, while the concentration of chloride anions increased. It has been concluded that the physiological state of all investigated roach specimens was normal.

Climate Change in the Hydrometeorological Parameters of the Black and Azov Seas (1980–2020)

To study the nature of climate change in the hydrometeorological parameters of the Black and Azov Seas—surface air temperature (SAT), sea surface temperature (SST), ice cover, and sea level—under conditions of ongoing global warming, we used reanalyses and remote sensing data, as well as information from known publications of recent years. It was found that against an increase in SAT over the Black–Azov Sea region (+0.053°C/year in 1980–2020) and SST of the Black Sea (+0.052°C/year in 1982–2020), the values of these parameters in the 2000s differ significantly from those in the 1980s–1990s: the maximum average monthly summer and minimum average monthly winter temperatures have increased, as well as the number of mild winters. The average annual SST of the Black Sea, which practically did not exceed 15°C in the 1980s–early 1990s, has exceeded 16°C in most cases since 2010 (maximum 16.71°C in 2018). In the 2010s, the average monthly winter minima, with the exception of the winters of 2011/2012 and 2016/2017, did not fall below 8°С. A consequence of the increase in winter temperatures was a decrease in the ice concentration in the Sea of Azov (the trend of the mean monthly concentration is –1.2%/10 years). From about 2004–2010 in the Black Sea and since 2004 in the Sea of Azov, the tendency towards increase in their levels (on average) has been replaced by a slight decrease, so that the average positive trends for the period 1993–2020 (+0.32 ± 0.16 cm/year in the Black Sea and +0.21 ± 0.05 cm/year in the Sea of Azov) were approximately 2.5 times less than in 1993–2012. The reason for this decrease in levels (on average) in the last 10–15 years was apparently a decrease in the incoming part of the freshwater balance of both seas, which is indirectly confirmed by the observed increase in salinity of their waters.

Changes in native and introduced host–parasite networks

Introduced species can alter the dynamics and structure of a native community. Network analysis provides a tool to study host–parasite interactions that can help to predict the possible impact of biological invasions or other disturbances. In this study, we used weighted bipartite networks to assess differences in the interaction patterns between hosts and helminth parasites of native (Sea of Japan) and invasive (Black Sea and Sea of Azov) populations of Planiliza haematocheilus (Teleostei: Mugilidae). We employed three quantitative network descriptors, connectance, weighted nestedness and modularity, to gain insight into the structure of the host–parasite networks in the native and invaded areas. The role of parasite species in the networks was assessed using the betweenness centrality index. We analyzed networks encompassing the whole helminth community and subsets of species classified by their transmission strategy. The analyses were downscaled to host individual-level to consider intraspecific variation in parasite communities. We found significant differences between networks in the native and invaded areas. The latter presented a higher value of nestedness, which may indicate a co-occurrence between parasite species with many connections in the network and species with fewer interactions within the same individual-host. In addition, modularity was higher in the native area’s networks than those of the invaded area, with subgroups of host individuals that interact more frequently with certain parasite species than with others. Only the networks composed of actively transmitted parasites and ectoparasites did not show significant differences in modularity between the Sea of Azov and the Sea of Japan, which could be due to the introduction of a part of the native community into the invaded environment, with a lower diversity and abundance of species. We show that network analysis provides a valuable tool to illuminate the changes that occur in host–parasite interactions when an invasive species and its parasite community are introduced into a new area.