Volume 2, Number 4

 

Environmental Concerns and the State of the Aquatic Environment

Results of marine scientific research of the Southern Scientific Centre of the Russian Academy of Sciences (SSC RAS) in the Sea of Azov in 2003–2018. Part 2: Hydrobiology.
Berdnikov S.V., Kleshchenkov А.V., Kreneva K.V., Glushchenko G.Yu., Dashkevich L.V., Kulygin V.V., Gerasyuk V.S., Saprygin V.V., Bulysheva N.I.
Abstract. The article presents the results of hydrobiological studies of the Sea of Azov, conducted since 2003 by the Southern Scientific Centre of the Russian Academy of Sciences, using both classical hydrobiological methods and modern geoinformation technologies. Analysis of the interannual and seasonal variability of the hydrobiological community allowed to characterize modern features of two annually repeated peaks in the development of phytoplankton (spring and more intense summer-autumn ones). The results of measurements of chlorophyll α concentration and primary production, and quantitative analysis of phytoplankton indicate a tendency for an increase in the autotrophic component in the water body and a shift of its maximum development zone to the mouth of the Don River. In the development of the microzooplankton community against the background of an increase in the water salinity, a decrease in the qualitative and quantitative characteristics of ciliate plankton was observed, most pronounced in the cold period of the year. The results of winter studies also demonstrated the decisive influence of the nature of winter not only on the intensity of phytoplankton development in spring, but also on the magnitude of its biomass in summer. Long-term monitoring makes it possible to note some “diminishment” and structural changes in the hydrobiont community: a decrease in the role of microalgae due to an increase of the share of ultraphytoplankton in its total biomass by 1.3 times, and the microzooplankton complex of common species mainly consisting of species of a small-sized group. As a result of the salinization process in the Sea of Azov, the number of cases of marine species invasion and naturalization and the expansion of the distribution areas of these species has increased. In the spatial structure of phytoplankton, narrowing of the ranges of fresh and brackish-water species and the expansion of the ranges of marine species are noted. For the last 15 years, among the representatives of the hydrobionts fauna, three types of shell ciliate infusoria tintinnids and three species of polychaetes, which significantly changed the composition of bottom communities, naturalized in the Sea of Azov.
Keywords: Sea of Azov, satellite images, primary production, chlorophyll α, phytoplankton, zooplankton, ciliate plankton, benthos, alien species.

Basic aspects of  the biogenic elements balance in the Azov Sea.
Kosenko Yu.V. 
Abstract. This article presents the basic aspects of the dynamics of biogenic elements in the Azov Sea, based on literature data and our field research, conducted recently in different seasons of the year from 1998 to 2018.
Correlation relationships of the main factors, affecting the change in the content of biogenic salts, are presented, and seasonal aspects of the dynamics of the mineral forms of nitrogen, phosphorus and silicon are given. It has been established that the Taganrog Bay is affected by the Don River flow to a greater measure, and in the sea, the significant role in the dynamics of biogenic elements is played by intrabasin processes. The importance of the river flow influence is shown by the supply of biogenic elements to the Taganrog Bay, in which not only the volume of river flow but also the general antrhopogenic pressure on the Lower Don and the Taganrog Bay area are crucial factors. Bottom hypoxia in the summer season plays a prominent role in enriching the water column with phosphates and ammonium nitrogen. In estimation of the dynamics of biogenic elements in the Azov Sea, the seasonal processes of mineralization of organic substances, the rate of recycling of biogenic compounds, life cycle of phytoplankton, wind speed over the sea surface, formation of density and oxygen stratification of water masses, water exchange with the Black Sea, bottom sedimentation, outwashing from rock material, and introduction of elements with atmospheric precipitations should also be taken into account. All factors, affecting the change in the concentration of mineral forms of nitrogen, phosphorus and silicon in water, are given in the form of flowcharts.
Keywords: Azov Sea, ammonium nitrogen, nitrite nitrogen, nitrate nitrogen, phosphates, silicic acid, balance of biogenic elements.

 
Water toxicity of the Don River mouth area by bioassay battery data.
Bakaeva E.N., Taradayko M.N., Ignatova N.A., Davydova N.S.
Abstract. At present, toxicity is one of the most important characteristics of surface water quality. The Don River mouth area is characterized by the change in surface water quality due to influence of the dissolved substances of anthropogenic and natural origin, incoming with the waters of the Lower Don River tributaries and diffused runoff from the water catchment basin. The research is aimed to assess water toxicity in the Don River mouth area from Aksay to Azov in the summer months by means of a bioassay battery. Water samples were collected using a vessel at the Roshydromet (Federal Service for Hydrometeorology and Environmental Monitoring of Russia) section line. Bioassay was carried out in accordance with the Federal Environmental Instruments of Russia and Roshydromet Regulations. Autotrophic (microalgae Chlorella vulgaris, Tetradesmus obliquus, higher plant Raphanus sativus) and heterotrophic (Daphnia magna) test organisms were used. The number of toxic samples in July and August was almost the same. For both months, the areas, where water toxicity was detected, coincided with the places of water intake and sewage discharge of Rostov-on-Don city. Water samples, taken below the second discharge outlet of Rostov-on-Don, were most toxic and retained their inhibiting effect even after dilution. In July, toxicity was also detected above the confluence of the Aksay River branch with the Don River and below the discharge outlet of the city of Azov. In August, the effect of undiluted water samples changed to the inverse and became stimulating, as opposed to the July bioassay data. An increase in the inhibiting but non-toxic effect of water downstream and with depth was noted. Deep water layers were characterized by acute toxic effects. The water at individual sampling sites had diverse (inhibiting or stimulating) effects on different test subjects. By optical density endpoint, the most sensitive test subject was Chlorella vulgaris; by mortality endpoint, the least sensitive ones were Daphnia magna crustaceans. The study of water toxicity in the mouth area of the Don River is necessary to carry out using bioassay battery with endpoints more sensitive than mortality. Water toxicity at the mouth area of the Don River in 2016 decreased compared with the water toxicity data based on bioassay from the previous twenty-year period.
Keywords: toxicity, phytotoxicity, surface water, Don River, bioassay battery.
 

Biology and Ecology of Aquatic Organisms

Arsenic in the commercial freshwater fish species of  the North-Caucasus Region and in the water bodies they inhabit.
Korablina I.V., Barabashin T.O., Katalevsky N.I., Evseeva A.I.
Abstract. The research results on the arsenic content in the water and bottom sediments of freshwater bodies of the Republic of Adygea, Krasnodar Krai, Stavropol Krai, and Rostov Region are given for the period of 2016– 2018. The levels of pollution of the habitat of aquatic biological resources have been estimated in accordance with the standards for freshwater bodies of fisheries importance and the average long-term values. The averaged results are presented for the organs and tissues of such commercial fish species as the pike perch (zander), crucian carp, white bream, European perch, common bream and the roach caught in the Krasnodar, Takhtamukaysk, Otkaznensk, Novotroitsk, Chograysk, Kryukovsk, Varnavinsk, Veselovsk, Proletarsk and Ust-Manych Reservoirs, the Don River, the Kuban and Mokraya (Wet) Buyvola Rivers. The levels of arsenic accumulated in the muscles and gonads of the fish have been compared in accordance with the Russian Sanitary Rules and Norms for Food Quality (SanPiN). It is shown that water and bottom sediments in water bodies of the Krasnodar Krai are the most polluted with arsenic. The determination of arsenic in the fish and the water bodies under investigation has been carried out in accordance with the procedures developed in the Azov-Black Sea Branch of “VNIRO” (“AzNIIRKH”).
Keywords: water reservoirs, North Caucasus Region, arsenic, water, bottom sediments, hydrobionts, accumulation, concentration.
 

Investigation of the genetic structure of the Black Sea turbot Scophthalmus maeoticus (Scophthalmidae) population in the Azov  and Black Seas.
Bessonova N.A., Nebesikhina N.A.
Abstract. In the Russian Federation, the Black Sea turbot Scophthalmus maeoticus (Pallas, 1814) is one of the most important aquatic species for aquaculture; it is promising for domestic practice of both artificial reproduction and commercial aquaculture. In the near future, the Black Sea and Azov populations of the Black Sea turbot will be used to form the broodstocks and obtain juveniles. For this purpose, eight loci of the Black Sea turbot Scophthalmus maeoticus, which have been tested on three samples (Crimean fishing area of the Black Sea, Caucasian fishing area of the Black and Azov Seas), were analyzed. A sample from the Baltic Sea was used as an out-group. As a result of the analysis, the value of average expected heterozygosity, the number of private alleles, the variability of the investigated loci, the deviation from the Hardy-Weinberg equilibrium, the level of genetic differentiation, and the percentage of migrants per one generation between the four studied samples have been determined, as well as their genetic distance from each other.
Keywords: Black Sea turbot Scophthalmus maeoticus, turbot Scophthalmus maximus, genetic structure, microsatellite loci (STR).
 

Guidelines for determining the age of the Antarctic fish species (Dissostichus mawsoni (fam. Nototeniidae),  Macrourus caml (fam. Macrouridae)).
Misar N.A.
Abstract. Methodology for age determination of the Antarctic fish species, in particular fish belonging to Antarctic toothfish Dissostichus mawsoni (fam. Nototeniidae) and caml grenadier Macrourus caml (fam. Macrouridae) species, using otoliths is presented. This methodology has been improved and adapted to modern specialized electronic tools and equipment. In place of the customary technique of obtaining a transverse section of an otolith through its core using a high-speed saw, an otolith was ground down to its transverse center with a grinding wheel and then baked with a heat gun at the temperature 350 °С and duration of exposure 3 minutes. The counting of the annual rings was carried out in digital photographs. It allowed for simplified preparation and processing of examination items to obtain reliable data on the age of the investigated Antarctic fish species. This methodology shows relatively high quality of processing the preparations, which ensures that obtained data on fish age are reliable; these data are vital for mathematical modelling of populations, for stock assessment, and for estimation of population abundance, which, in turn, ensures sustainable fisheries.
Keywords: age determination, hyaline zone, opaque zone, growth rings, otoliths, grinding, polishing, baking.
 

Microsatellite variability of the European anchovy Engraulis encrasicolus Linnaeus, 1758.
Nebesikhina N.A., Barmintseva A.E., Timoshkina N.N., Vodyasova E.A.
Abstract. In the Azov and Black Sea Basin, the European anchovy accounts for the majority of trawl fleet fishing; its exploitation is carried out in the context of distinguishing two populations of stock management: the “Azov anchovy” and the “Black Sea anchovy”. Conventionally, exploitation of the “Azov anchovy” stock is conducted using precautionary approach, and, on the contrary, the “Black Sea anchovy” fishing is not under any limitations. To make a more accurate forecast of the anchovy stock and achieve its sustainable yield, it is necessary to study inter- and intrapopulation composition of the Azov and Black Sea anchovy. Ten samples of the European anchovy (Engraulis encrasicolus) from the Black, Azov and Adriatic Seas, and the Bay of Biskay have been investigated by six microsatellite loci. To ascertain intraspecific status of the anchovy from the Azov and Black Sea Basin, 7 microsatellite loci have been used. Cluster analysis, analysis of genetic distances (Fst), and principal component analysis (PCA) have shown the existence of differentiation between populations of the European anchovy that coincided with three marine basins. AMOVA analysis has shown a high level of intrapopulation variance (96 %) in the European anchovy from the Azov and Black Sea Basin, maintained by means of active migration within the range of this species. Analysis of genetic variability of STR-loci in different spawning groups and morpho-groups of the Azov and Black Sea anchovy has not identified intraspecific differen tiation. Phenotypic distinction of the Azov and Black Sea anchovy is paratypical. Taking into account the absence of intraspecific differentiation between the “Azov” and “Black Sea” anchovy, it can be concluded that it is important to take a rational and balanced approach to utilization of the common Azov and Black Sea anchovy stock to avoid its overfishing.
Keywords: European anchovy, Engraulis encrasicolus, Azov Sea, Black Sea, genetic structure, microsatellite loci (STR).
 

Results of the zoobenthos studies in the North-Eastern Black Sea according to the data obtained in 2016–2017.
Frolenko L.N., Zhivoglyadova L.A., Kovalev E.A.
Abstract. Based on the materials of summer and autumn complex research expeditions conducted in 2016 and 2017, the distribution and quantitative characteristics of zoobenthos and its main groups (molluscs, polychaetes, crustaceans, and other species) inhabiting the north-eastern Black Sea, have been considered. In summer, 82 zoobenthos species were identified, whereas 90 species were observed in autumn. Among these species, polychaetes, molluscs and crustaceans were most diverse. Seasonal variability of quantitative and species composition of the zoobenthos was estimated. The average abundance of bottom organisms in summer was 5,172 ind./m2, while in autumn it amounted to 4,235 ind./m2. The zoobenthos biomass in summer and autumn equaled 118.2 g/m2 and 134.8 g/m2, respectively. Polychaetes were the dominant group in benthos, among them Aricidea (Strelzovia) claudiae Laubier, 1967, Prionospio cirrifera Wirén, 1883, Heteromastus filiformis (Claparède, 1864) and Micronephthys longicsornis (Perejaslavtseva, 1891) were the most developed and had high occurrence level. The variability of the total benthos biomass was determined by the presence of bivalve molluscs, which were one of the main components of the bottom communities in the north-eastern Black Sea. The bivalve molluscs Pitar rudis (Poli, 1791), Gouldia minima (Montagu, 1803) and Mytilus galloprovincialis Lamarck, 1819 developed intensively on silty-shelly and silty substrates, while Chamelea gallina (Linnaeus, 1758) occurred on sandy-shelly bottom.
Keywords: North-Eastern Black Sea, zoobenthos, distribution, abundance, biomass, bivalves, Pitar rudis, Gouldia minima, Chamelea gallina, polychaetes, crustaceans.
 

Fisheries and Processing of Aquatic Bioresources

Technological standardization of discards and losses during horse mackerel Trachurus mediterraneus ponticus processing.
Esina L.M., Gorbenko L.A.
Abstract. Technological standardization means determination of a necessary measure (norm) of raw material consumption while producing food items, derived from aquatic living resources or aquaculture target species. At present, there are no standards in force that could determine losses, discards and final output of dressed Mediterranean horse mackerel Trachurus mediterraneus ponticus, caught in the Black and Azov Seas. In this article, the main types of dressing, used during the manufacturing process of salted and smoked horse mackerel products, are analyzed. The results of experimental control operations on standardization of discards, losses and output of both headed horse mackerel and dressed horse mackerel, which have been conducted in production and laboratory conditions, are presented. It is shown that a fishing area does not influence the output of processed horse mackerel. The output of the dressed fish caught in the Black Sea made up 63.1 %, from the Sea of Azov —
62.9 %. It is noted that weight percentage of horse mackerel discards when processing it during its spawning period is higher than in other catch periods due to the presence of eggs and milt. For the horse mackerel of the spawning period, the output of the dressed fish equals 57.8 %, of the post-spawn period — 64.4 %. As it has been ascertained, the obtained values of the dressed horse mackerel output belong to normal distribution. Statistical processing of the obtained data and their adherence to the normal distribution law give evidence of the possibility to determine the unified average annual output norms for processed mackerel irrespective of the area and time of its catch.
Keywords: Trachurus mediterraneus ponticus, fish processing, discards and losses, yield of processed fish, technological standardization, experimental control operations, dressed fish.
 

Informational Messages

All-Russian Scientific Conference “Seas of Russia: Fundamental and Applied Research” Announcement of the 9th All-Russian Scientific Conference “Commercial Invertebrates”.
Panov B.N., Borovskaya R.V.
Abstract. This informational message is prepared using the data from the official website of the Marine Hydrophysical Institite http://mhi-ras.ru/. From the 23rd to 28th of September, 2019, the All-Russian Scientific Conference “Seas of Russia: Fundamental and Applied Research” was held on the basis of the Marine Hydrophysical Institute of the Russian Academy of Sciences; it was dedicated to the 90th Anniversary of the Marine Hydrophysical Institute. The program of this conference included 8 plenary reports, and 151 reports have been presented during breakout sessions, divided between the sections “Fundamental studies of the processes of marine environment formation and evolution”, “Applied problems of assessing and predicting the state of marine systems and the processes of their interaction with the atmosphere”, and “Remote research of the marine environment processes and phenomena”. Within the poster session, 65 reports were presented. Among the reports, included in the conference program, three reports have been presented by the researchers of the Azov-Black Sea Branch of the FSBSI “VNIRO” (“AzNIIRKH”). Following the proceedings of the Conference, a collection of its abstracts has been published.
Keywords: conference, fundamental research, remote research, applied research, plenary reports.