Upper Quaternary water level history and sedimentation in the northwestern Black Sea

Gas migration pathways and slope failures in the Danube Fan, Black Sea

Purpose . Waters of the North-Western part of the Black Sea (NWBS) receiving the discharges from three large rivers (255,7 km3 per year) differ from the waters of the Black Sea in their unique physical and chemical characteristics. In this context one of the most important tasks is assessment of the large rivers’ discharge impacts on the estuarine areas of the Black Sea. The objective of the work has been to reveal the variability of physical and chemical characteristics of marine water near the Zmiinyi Island under impact of the Danube discharge and wind conditions in 2004-2013. Materials & Methods . Results of meteorological (wind speed and direction, air temperature), hydrological and hydrochemical observations and measurements (temperature, transparency, salinity, density and relative oxygen content, pH value) performed in the island coastal waters in 2004-2013 have been used as the source data. Statistical and correlation analysis performed for the three sectors of wind direction in the Zmiinyi Island area (“Danube”, “NWBS” (north-western Black Sea) and “Black Sea”) have been used as a basic research tools. Results. Many-years trends in the changes of the main physicochemical characteristics of marine waters near the Zmiinyi Island have been analysed. For the period May-December 2004-2013 the tendency of average monthly water temperature values decreasing has been identified, as well as the tendency of increasing of average monthly values of sea level, transparency, salinity, pH, concentration of and saturation with dissolved oxygen. Quantitative confirmation of significant influence of the Danube discharge on salinity, transparency and water level near the Zmiinyi Island has been received. For the period May-December 2004-2013, increasing repeatability of wind directions was revealed for the sector “Danube” and decreasing repeatability for the sector “NWBS”. No significant trends have been established for repeatability of the “Black Sea” sector. Division of datasets into wind sectors enabled us to establish certain regularities in the hydrological and hydrochemical regime of marine water in the Zmiinyi Island area. In particular, closer connections of salinity, transparency and relative oxygen content with wind speed were identified for the sectors “Danube and “NWBS” and insignificant connections for the “Black Sea” sector. Closer connections of pH, oxygen concentration and air temperature were revealed with the speed of wind from the sectors “Danube” and “Black Sea” and less significant connections for the “NWBS” sector.

Biomass and Size Composition of the Comb Jelly Mnemiopsis sp. in the North-western Black Sea During Spring 1997 and Summer 1995

Hydrological changes in eastern Europe during the last 40,000 yr inferred from biomarkers in Black Sea sediments

In a single methodological basis, based on complex lithologic and stratigraphic and petrophysical studies, logging interpretation, beds correlation, were selected and indexed 45 productive horizons of Cenozoic sediments at Black and Azov seas shelf (Ukrainian sector): МU-1, МU-2, МU-3, МU-4, МU-5, МU-6, МU-7, МM-1, МM-2, МL-1, МL-2, МL-3, МL-4, МL-5 and МL-6 in Miocene sediments; ОU-1, ОU-2, ОU-3, ОU-4, ОU-5, ОL-1, ОL-2, ОL-3, ОL-4, ОL-5, ОL-6, ОL-7, ОL-8, ОL-9, ОL-10 and ОL-11 – Oligocen; ЕU-1, ЕU-2, ЕM-1, ЕM-2, ЕM-3, ЕM-4, ЕM-5, ЕL-1, ЕL-2 and ЕL-3 – Eocene, PU-1, PL-1, PL-2 and PL-3 – Paleocene. The name of each productive horizon is the sum of the abbreviations of names of department and sub-department, which is the horizon, and the numeral indicating its serial number.Single scheme of indexing and correlation was composed. Key words: productive horizon, Cenozoic sediments, Ukrainian waters of the Black and Azov Seas References Atlas of oil and gas in Ukraine. V.VI. South oil and gas region. 1998. Lviv. UNGA. 224 p. (in Ukrainian). Boboshko A.V., Vakarchuk G.I., Vinnichenko L.G. et al.1974. The scheme of correlation and unified synonymy oil and gas horizons of the Lower Carboniferous of the Dnieper-Donets basin (guidelines). Kharkiv. 52 p. Vakarchuk G.I., Vinnichenko L.G., Kononenko L.P. 1990. The new scheme of indexing and correlation of the productive horizons of the Lower Carboniferous of the Dnieper-Donets basin. Geological Journal. #6. S. 109-115. Stratigraphic Code of Ukraine. 2012. Resp. editor P.F. Gozhyk. 66 p. Gozhik P.F. 2006. Oil-gas facilities in Ukraine. Scientific and practical basis for finding hydrocarbons in the Azov Sea. Kyiv. EKMO. 340 p. (in Ukrainian). Gozhik P.F. 2007. Oil-gas facilities in Ukraine. Scientific and practical basis for finding hydrocarbons in the northwestern Black Sea shelf. Kyiv. ЕКМО. 231 p. (in Ukrainian). State balance of mineral reserves Ukraine. 2012. Кiev, SSPE Geoinform Ukrainin, 3284 p. (in Ukrainian). Oil and gas potential of the northwestern Black Sea. 1995. Series «Oil-gas potencial water area of the Black Sea and the Sea of Azov». V.2. Kyiv. Ukrainian Oil-gas institute. 250 p. (in Ukrainian). Oil and gas potential of the Azov Sea 1995. Series «Oil-gas potencial water area of the Black Sea and the Sea of Azov». V 1. Kyiv. Ukrainian Oil-gas institute. 166 p. (in Ukrainian). Oil and gas potential Kerch-Taman Black Sea shelf, continental slope and deep-sea depression Black Sea. 1996. Series «Oil-gas potencial water area of the Black Sea and the Sea of Azov». V.2. Kyiv. Ukrainian Oil-gas institute. 186 p. (in Russian). Ukraine's oil and gas province. 1981. Kyiv. Naukova dumka, 172 p. (in Russian). Forecast oil and gas exploration in the south of the USSR and adjacent waters. 1981. Ed. V.V. Glushko and S.P. Maximov. Moscov. Nedra. 240 p. (in Russian). Murasta W.А., Baschkirov G.L., Karpenko О.М. 2012. On the issue of allocation of productive horizons in the Paleogene and Neogene sediments Ukrainian shelf of the Black and Azov Seas. Problems of Oil and Gas Industry. Proceedings of SE Naukanaftogaz NAK Naftogaz Ukraine. Kyiv.Vol. 10. P. 97-104 (in Ukrainian). Creation of unified directory breakdowns productive horizons Cenozoic sediments within the areas of the Black and Azov seas based on a single indexing and correlating. 2011. Report on implementation of the provision of geological and thematic work. Responsibility G.L. Bashkirov and I.I. Ishchenko. SE Naukanaftogaz. Vischneve, №16/200. Book 1,2. 503 p. (in Ukrainian). Handbook of Petroleum Geology. 1984. Ed. N.А. Yeremenko. М. Nedra. P. 480. (in Russian). Hanin А.А. 1969. Reservoir rocks of oil and gas and their study. M.: Nedra. 366 p. (in Russian).

Two IFREMER oceanographic surveys carried out in the northwestern Black Sea in 1998 and 2002 complement previous seabed mapping and subsurface sampling by various international expeditions. They show that the lake level rose on the continental shelf to at least the -40 to -30 m isobath based on the landward limit of a Dreissena layer representative of very low salinity conditions ( 50/00). The Black Sea then shows clear evidence for an onset of marine conditions at 7150 BP. From these observations, Ryan et al. (1997) concluded that the Black Sea could have filled abruptly with saltwater cascading in from the Mediterranean. Despite critical discussions of this interpretation, recent IFREMER discoveries of well preserved drowned beaches, sand dunes, and soils appear to lend support to the flood hypothesis. This new evidence includes (1) multibeam echo-sounding and seismic reflection profiles that reveal wave-cut terraces at about -100 m, (2) Romanian shelf cores that show an erosion surface indicating subaerial exposure well below the sill of the modern Bosphorus, (3) 14C ages documenting a colonization of the former terrestrial shelf surface by marine molluscs at 7150BP, (4) evidence of sea water penetration into the Black Sea in the form of recent canyon heads at the Bosphorus outlet, and (5) palynological analysis and dinocyst studies that pinpoint the arrival of freshwater during the Younger Dryas and, later, the rapid replacement of Black Sea dinocysts by a Mediterranean population.

<p>The Danube Deep-Sea Fan, situated in NW Black Sea, is one of the most developed deep-sea sedimentary structures in Europe (Panin & Jipa, 2002). In 2018, in the framework of the uBiogas Project (24PCCDI/2018), several cores were acquired from the aforementioned area. In this study, high resolution microfaunal analyses coupled with sedimentological and geochemical ones, were performed on two gravity cores that revealed changes since the Last Glacial Maximum. The cores have been collected from two secondary canyons, situated in the E of the Danube Canyon, at 655,7 m (MN183_3_GC_1) and 1315 m water depths (MN183_8_GC_1). In both cores, three stratigraphic units as described by Ross & Degens (1974) were identified (oldest first): Unit 3 (Lacustrine lutite), Unit 2 (Sapropel Mud) and Unit 1 (Coccolith Mud).</p><p>The sediments of Unit 3 correspond to the Last Glacial Maximum and are marked by the presence of the cold-water ostracod species. The cores contain a reddish-brown clay and silty interval belonging to the post-glacial melt-water pulse of the Heinrich Event 1. In these deposits the ostracod assemblages display a high diversity and abundance. The CaCO<sub>3</sub> amount is very low, i.e. below 15%, except for the upper part where it reaches more than 50%. The samples of Unit 3 contain nannofossil assemblages that are entirely composed of reworked species from Cretaceous, Paleogene, Early and Middle Miocene intervals.</p><p>In Unit 2 (the sapropel), very few specimens of ostracods were identified, towards the top. During this depositional interval CaCO<sub>3 </sub>values are dropping again below 15%. The high abundance of the calcareous nannoplankton species Braarudosphaera bigelowii in the upper part of Unit 2 suggests the first strong influx of marine waters into the Black Sea basin.</p><p>In the youngest Unit 1, a brackish-marine ostracod assemblage, with low diversity and abundance was identified. This interval is characterized by the presence of polyhaline ostracods with Mediterranean origin. The ostracods from this assemblage tolerate salinities comprised between 17-21 ‰ and characterize a sub-littoral environment. The CaCO<sub>3</sub> values are increasing to more than 50%. During the depositional interval of Unit 1 the environmental was definitely a marine one, probably with a constant salinity of surface waters over 17 ppm, allowing the calcareous nannoplankton species Emiliania huxleyi and Braarudosphaera bigelowii to proliferate. The great abundance of the two taxa and especially of Emiliania huxleyi indicates the existence in the basin of a high nutrient input.</p><p>The financial support for this paper was provided by the Romanian Ministry of Research and Innovation, through the Programme 1 – Development of the National System of Research – Institutional Performance, Project of Excellence in Research-Innovation, Contract No. 8PFE/2018 and by the Project uBiogas, contract no. 24PCCDI/ 2018.</p><p> </p><p>Panin, N., Jipa, D., 2002. Danube river sediment input and its interaction with the northwestern Black Sea. Estuarine Coastline Shelf Science 54: 551–562.</p><p>Ross, D.A., Degens, E.T., 1974. Recent sediments of the Black Sea. In: Degens E.T. and Ross D.A. (Eds.), The Black Sea: Geology, Chemistry, and Biology. American Association of Petroleum Geologists, Tulsa, USA: 183–199.</p>

A post Younger Dryas Black Sea regression identified from sequence stratigraphy correlated to core analysis and dating

Mycobiota of the marine area of Odessa region was studied (30°70′00′′-31°00′00′′N, 46°23′00′′-46°60′00′′E) (See Fig. 1). Hydrological and hydrochemical regimes of the marine area of Odessa region in the northwestern Black Sea are affected by the discharge of the Dnieper (93.4%) and the Southern Bug (5.7%) rivers, the permanent anthropogenic discharges of the cities of Odessa, Chernomorsk (Ilyichyovsk), Yuzhnyi and their ports, shipping, dredging, and the open sea. The aim of this work was to study the species composition, the number of colony forming units (CFU) and the dynamics of the spatiotemporal distribution of reared microfungi as a function of abiotic factors and the trophic level of seawater in this area. Water samples were taken in summer and autumn 2008-2012 in the surface (1 m depth) and bottom (7-24 m depth) layers. The samples were taken, at least, in three replicates. The results of processing 258 samples from 22 stations were analyzed. The effects of environmental factors (water temperature, salinity, dissolved oxygen, five-day biochemical oxygen demand, petroleum hydrocarbons, dissolved metals Cu, Zn, Ni, Cd and suspended particulate matter) were studied in 140 samples (See Table 1). Micromycetes were isolated on Czapek’s medium prepared in sea water. 1 ml of sample water was added to a Petri dish and filled with medium cooled to approximately 36-40 °C. To suppress the growth of bacteria, 0.03% chloramphenicol was added to the medium (by volume of the medium). Cultivation was carried out at a temperature of 18-20 °С for 2-8 weeks. Micromycetes were identified by morphological and cultural characteristics according to Vera Bilay and Eleonora Koval’ (1988) and GS De Hooh ea tl. (2000). Nomenclature, and taxonomy of fungi correspond to The Index Fungorum database. The ecological analysis of mycocomplexes was carried out according to: species composition, the number of species in complexes, frequency of occurrence of a species and the number of colony-forming units (CFU / L). In this research, 50 fungal species of 19 genera, 14 families, 9 orders, 4 classes of the division Ascomycota were revealed. Fungal taxa from Odessa region were grouped into families. The family Aspergillaceae included the genera Aspergillus, Penicillium and Talaromyces (27 species); the family Pleosporaceae included the genera Alternaria and Stemphylium (8); and there were 3 species of the genus Cladosporium from the family Cladosporiaceae. In total, 76.0% of species found were from the three families (See Table 2). Using Average Taxonomic Distinctness index, AvTD (Δ+), and Variation in Taxonomic Distinctness index, VarTD (Λ+), features of the taxonomic diversity of mycocomplexes were revealed. These indices were calculated from a matrix of micromycete species from the region under study combined with the fungi list (master list, 219 species) of the Black Sea pelagic zone. In the analysis, the taxonomy levels from Species to Kingdom were included. For the indices Δ+ and Λ+, 95% probability funnel graphs were plotted, and their mean expected values were calculated for mycobiota of the region under study and for mycocomplexes from each station. It was found out that the mean expected values of the index Δ+ for mycobiota of the marine area of Odessa region and the stations are considerably lower, and index Λ+ values are higher than those for the sea as a whole (See Fig. 2 and 3). According to literature sources, no significant seasonal and inter-annual changes in the trophic status of the region occurred in 1992-2010. It was transitional between mesotrophic and eutrophic. The long-term mean TRIX value was 5.3 (4-5: medium trophic level; 5-6: high trophic level and poor water quality). In the species composition and numerical structure of mycocomplexes of the mesotrophic and eutrophic zones, no significant differences were detected. Over the entire period of this research, a relatively uniform distribution of the mean abundance of fungi over the area and depth was noted (See Table 3). No significant correlation was found between abiotic parameters under study and micromycete abundance over the horizons, seasons, sampling dates, location of stations, as well as mesotrophic and eutrophic zones. In the region, 44% of fungi-indicators of different kinds of pollution were registered. In the areas of stormwater runoff and wastewater treatment plant discharges, the indicator value (IndVal) was the largest for melanin-containing fungi Cladosporium cladosporioides (28.3%), Alternaria alternata (17.5%), and Aspergillus niger (12.3%), which are resistant to several adverse environmental factors. In the eutrophic zone, large values of the indices were found in Aspergillus clavatus (21,2%), Penicillium expansum (17,7%), Penicillium citrinum (16,1%), Al. tenuissima (12,5%), and in A. fumigatus (60%), Al. alternata (40%) and A. niger (35,7%) in places of local oil pollution. It is established that in the entire marine area of Odessa region, the formed mycocomplexes have a high similarity in species and numerical structure, and therefore, they can be considered as a single community.

Piebaldism is one of three types of hypopigmentation of animals, when some areas on the skin have no pigments. Anomalously white cetaceans are rare, although they have been reported in more than 20 different cetacean species, including the common bottlenose dolphin, which in the Black Sea is recognized as an endangered endemic subspecies — the Black Sea bottlenose dolphin (Tursiops truncatus ponticus Barabash-Nikiforov, 1940). Its main habitat in the north-western Black Sea region is the coastal waters, however, these dolphins also occur offshore. Thirty cases of anomalously white bottlenose dolphins have been reported from the Black Sea, which were unevenly distributed, and only a few sightings have been reported from the north-western Black Sea. Cetacean observations were conducted in the Ukrainian part of the north-western Black Sea waters in April 2017, onboard the research vessel "Auguste Piccard". All encountered cetaceans were photographed, and individual distinctiveness of dorsal fin images was used for their photo-identification. On 13 April 2017, four groups of up to four individuals of bottlenose dolphins were encountered in the same area at a distance of 61 km south of Odesa (34 km from the nearest coast). The depth at the observation site was about 20 m. The initially observed type of dolphins’ behavior was feeding. However, two groups changed their behavior and followed the vessel by 5–6 individuals for approximately 18 minutes. The joint group consisted of adults and one juvenile individual. Among the adults, there was one piebald specimen with white patches on its dorsal fin, peduncle, and tail fluke. The piebald dolphin was photographed and photo-identified. Our research has shown that piebald Black sea bottlenose dolphins occur not only in the coastal waters, but also in offshore waters of the north-western Black Sea. However, the frequency of such hypopigmentation in local populations remains unknown. Further intensive photo-identification and genetic sampling of local stocks of the Black Sea bottlenose dolphins are necessary for the assessment of their population genetic structure and its divergence.

Both the anaerobic and the aerobic oxidation of methane are fundamental microbial processes with far reaching influences on global element cycles and, consequently, on the physico-chemical nature of the hydro- and atmosphere. These processes lead to substantial removal of the radiatively active gas methane and are powerful factors in controlling the composition of ecosystems and the distribution of authigenic deposits at methane-rich sites. For instance, the sulfate-dependent anaerobic oxidation of methane (AOM) mediated by methanotrophic Archaea and sulfate-reducing Bacteria yields hydrogen sulfide and bicarbonate ions, which subsequently react with ions derived from pore waters and the water column to form sulfidic and carbonaceous minerals. The aerobic oxidation of methane, performed by obligate aerobic Bacteria particularly effective at oxic-anoxic boundaries, leads to the generation of carbon dioxide, which is a less radiative gas than methane but has higher residence times in the atmosphere.The geochemical characteristics of the contemporary Black Sea promote processes associated with the conversion of methane and are considered to resemble those of the Paleo/Mesoproterozoic global ocean. Geochemical and molecular microbiological considerations support the idea that the microbes involved in the AOM emerged before the Archaean – Proterozoic transition, and became more important in the Paleoproterozoic, when oceanic deep waters are thought to contain high amounts of methane and adequate amounts of sulfate. With the rise of atmospheric oxygen in the Paleo/Mesoproterozoic, substantial parts of the global ocean became oxygenated, which promoted the spreading of aerobic methanotrophs. Since then, biogeochemical remnants, like fossil seep deposits or lipid biomarkers strongly depleted in 13C, demonstrate the relevance of methanotrophy in Earth history.Methane in the contemporary Black Sea is mainly sourced from sedimentary gas reservoirs at emission sites like cold seeps and mud volcanoes. Detailed seismic and hydroacoustic investigations at deep-water cold seep areas on the Ukrainian shelf (northwestern Black Sea), the continental slope off Georgia (southeastern Black Sea) and at mud volcanoes located in the Sorokin Trough (northern Black Sea) provided insights into their subsurface structures, fluid migration pathways, and extents of gas plumes in the water column. This review considers recent studies on sources and migration pathways of methane, and its fate in the sediments in the water column of the Black Sea with special emphasis on the anaerobic and aerobic microbial methane consumption.KeywordsAuthigenic CarbonateCold SeepAnaerobic Methane OxidationEuxinic WaterSorokin TroughThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Extensive mass transport deposits (MTDs), which form a significant component of the stratigraphic record in ancient and modern deep water systems, mostly distributed in the continental margin of ocean basins worldwide. To date, no large‐scale MTDs have been found in Chinese terrestrial basins. Based on integrated analysis of the seismic, drilling, core and logging data, this article report MTDs have been found in Songliao terrestrial basin (SLTB), Northeast China. During the depositional period of the Upper Cretaceous Qingshankou Formation, slope break of lacustrine basins was an ideal discharge place for gravity depositions. Regional sedimentary study of MTDs reveals that Cretaceous‐age MTDs in SLTB were deposited in slope‐break environments by slide, slump and debris flow, and MTDs were mixed with little turbidite simultaneously. Besides the massive aspect, key features of MTDs are the common presence of deformational structures or soft‐sedimentary deformation, floating shale clasts, boudins, microfaults, distortion beddings, rotated sand debris. Detailed mapping of two three‐dimensional (3‐D) seismic surveys acquired in Yingtai (YT) and Haituozi (HTZ) areas reveals that MTDs are characterized by chaotic, mounded, and transparent seismic reflection. Growth fault, slope gully and geomorphology of the slope break greatly influenced the sedimentary process and external geometry of MTDs, and as a consequence, MTDs in SLTB exhibit classic fan‐like geometry and some special (non‐fan‐like) external geometry. Furthermore, fan‐like MTDs can be divided into three subcategories, including isolated fan, mother‐son fan and stacked fan. Non‐fan‐like MTDs can be divided into two subcategories, strip‐like MTDs and faulted‐pit MTDs. A new sedimentary model has been built for MTDs in SLTB. MTDs have become a new exploration and development target in the SLTB.

Systematic mapping of 3.5 kHz seismic facies (echo character) reveals the geometry, scales and distribution of Late Quaternary mass-transport deposits (MTDs) within the northern Gulf of Mexico (GOM) intraslope basin province and adjacent Sigsbee Abyssal Plain. The 3.5 kHz seismic facies indicate that localized MTDs are common in the intraslope mini-basins. MTDs of larger scale occur on the upper continental slope (e.g. East Breaks Slide Complex) and seaward from the eastern base of the Sigsbee Escarpment. Approximately 120 piston cores from these deposits “ground truth” the seismic facies interpretations and reveal that the sedimentary facies of the MTDs in intraslope basins contain a spectrum of slumps, slides and debris flows. Most MTDs are muddy deposits, but sandy MTDs are also common. The presence of sandy debris flows suggests that similar, more deeply buried MTDs may constitute significant reservoir sands. Many piston cores containing MTDs were biostratigraphi-cally and chemically zoned using G. menardii complex and calcium carbonate fluctuations to determine the timing and sourcing of MTDs in relation to glacio-eustatic sea-level changes associated with the Last Glacial and Holocene. This stratigraphic analysis indicates that the majority of downslope transport (including sandy turbidites, sandy and muddy debris flows, and slumps) occurred during the Last Glacial cycle. Downslope transport of MTDs during the Holocene Interglacial was rare.

Late Quaternary channel avulsions on the Danube deep-sea fan, Black Sea

Изучение таксоцена Annelida (Polychaeta), эпибионтов брюхоногого моллюска — вселенца Rapana venosa, продолжает цикл по описанию состава консорции самого крупного брюхоногого моллюска черноморского бентоса. Консорция R. venosa до сих пор является мало исследованной и неучтённой компонентой в структуре биоценозов шельфа Чёрного моря. Цель данной работы — изучить комплекс полихет консорции R. venosa. Задачи этого этапа: составление списка таксонов Annelida (Polychaeta) — эпибионтов рапаны; изучение биогеографической и трофической структуры таксоцена; исследование экологических связей полихет с ядром консорции. Для изучения консортного сообщества рапаны были осуществлены сборы в семи районах северной части Чёрного моря: 1 — Мамайя, Румыния; 2 — северо-западная часть Чёрного моря, Крымский сектор; 3 — Севастополь; 4 — Алупка; 5 — Ялта — Алушта; 6 — Карадаг; 7 — Керченский пролив. Сбор R. venosa в прибрежной зоне до глубины 15 м проводили тотально с использованием легководолазного оборудования, в более глубоководной зоне (до 40 м) — дночерпателем «Океан-50» с борта НИС «Профессор Водяницкий». Каждый экземпляр (пробу) рапаны помещали в отдельный пластиковый пакет с указанием района, глубины и биотопа. Всего отобрано и проанализировано 2411 проб, из них 977 — скальной рапаны и 1434 — песчаной. Покрытие эпибионтами раковины R. venosa (интенсивность обрастания) оценивали в процентах от общей площади внешней поверхности раковины. Таксоцен Polychaeta консорции R. venosa включает 31 вид, представляющий 31 род 15 семейств 2 подклассов. Бόльшая часть видов (18) относится к Errantia, половину из них составляют представители семейств Nereididae и Syllidae. К Sedentaria относятся 13 видов; наибольшее их количество (4) принадлежит семейству Serpulidae. Таксоцен Polychaeta консорции рапаны представлен тремя биогеографическими группами: аборигенные виды средиземноморско-атлантического генезиса (84 %), эндемики Чёрного моря (10 %) и современные виды-вселенцы различного географического генезиса (6 %). На песчаной рапане обнаружен 31 вид полихет, а на скальной — только 5. Показатели развития фауны полихет значительно различаются по глубинам и районам исследований. Наиболее разнообразны полихеты в бухтах г. Севастополя (район № 3) на глубинах 2–10 м; максимальная глубина обнаружения полихет (40 м) соответствует наибольшей глубине отбора рапаны. Площадь покрытия раковины рапаны полихетами достигает 70 %, встречаемость в отдельных районах составляет до 95 %. Максимальное число видов, обнаруженных на отдельном экземпляре рапаны, — 8; в среднем на особях R. venosa отмечено 2–4 вида полихет. Таксономическое разнообразие и обилие Polychaeta определяют их значимость в консорции R. venosa. Благодаря инвазионному хищному моллюску R. venosa полихеты получают дополнительные возможности для распространения на шельфе Чёрного моря.