The Zernov's Phyllophora Field (ZPF) is a water area in the northwestern Black Sea (NWBS) that occupied about 11 000 km 2 in the early 20 th century. Since 2008, a water area of 4025 km 2 has been given the status of a botanical sanctuary of national importance «Zernov's Phyllophora Field». The goal of the present study is to assess the species richness and quantitative development of macrozoobenthos of the ZPF and their long-term variations under the current conditions of de-eutrophication of the Black Sea basin. The work is based on the material of 43 benthos stations performed in 2010-2013 within an area of 8400 km 2 in the ZPF. In 2010-2013, a total of 162 macrozoobenthos species were identified: Polychaeta (49 species), Mollusca (39), Crustacea (43), Ascidiacea (6); the other taxa comprised 25 species. The current level of species richness of macrozoobenthos is the highest for the entire historical period of the ZPF studies. The mean abundance and wet biomass of macrozoobenthos were estimated at 2417 ± 175 individuals/m² and 283 ± 32 g/m² (without mantle cavity fluid of bivalves). Values for Polychaeta amounted to 1017 individuals/m² and 6 g/m², Mollusca -887 individuals/m² and 256 g/m², Crustacea -165 individuals/m² and 1.3 g/m², Ascidiacea -42 individuals/m² and 17 g/m². The biomass of the dominant species, the filter-feeders Mytilus galloprovincialis, reaches 73% of the total macrozoobrnthos biomass. Our research of the long-term alterations in benthic macrofauna covers the period 1957 to 2013, including the pre-crisis time of the Black Sea ecosystem (1957)(1958)(1959)(1960), its crises of the second half of the 20 th century (1979, 1984, 1991) and the modern (post-crisis) stage (2010)(2011)(2012)(2013). Based on the maps of biomass spatial distribution for all periods mentioned above, the mean values and the total stocks of macrozoobenthos within the area 8400 km 2 of the ZPF were evaluated. The long-term changes of the macrozoobenthos biomass were analysed in relation to the main factors adversely affected the bottom biocoenoses in NWBS -i.e. anthropogenic eutrophication, oxygen depletion and near-bottom hypoxia in summer, as well as the secondary siltation of the seabed due to intensive near-bottom trawling. The most critical period for the ZPF ecosystem state occurred in the late 1970s, when the mean biomass and the total stock of macrozoobenthos decreased by 7 times in comparison with the pre-crisis period. The data collected in the first decades of the 21 st century indicate the actual recovery of the mean macrozoobenthos biomass and of its total stock in the ZPF area to the level of 1957-1960, which is related to the improving of the general ecological situation in the region.Ключевые слова: Phyllophora, биомасса, запасы макрозообентоса, макрофауна бентоса, многолетняя динамика, морская особо охраняемая природная территория, численность Nature Conservation Research. Заповедная наука 2018. 3(4): 32-43
The results of the first studies of the ecosystem state of the underwater part of the channel, artificially created in the middle of the 20th century on the western shore of the Balaklava Bay (Sevastopol) as a naval base of the Black Sea Fleet for the submarines repair, are presented. Channel's ecosystem is determined by uniqueness of anthropogenic formation and considered as analogue of natural Black Sea cave. Hydrospelological survey of the channel and biological studies allowed assessing its current state, the nature of biofouling of its walls and anthropogenic and technical pollution of the bottom. Macrofauna of the channel wall biofouling is represented by the Mytilaster lineatus community, which has a high level of species abundance (about 80 species have been registered) and quantitative development. Both in taxonomic diversity and in quantitative terms, this community is comparable to the rocky substrate community near open Crimean coasts, but with a smaller share of crustacean group development. Due to weakened hydrodynamics, well developed fauna of bryozoans forming plurannual crusty structures and single sponges is observed on the channel's walls. In contrast to the channel walls biofouling, its bottom macrofauna has relatively lower quantitative and qualitative composition. Meiobenthos in the channel’s wall biofouling is represented by 18 higher taxa (type, class, order) of Protozoa and Metazoa with predominance of harpacticoids by abundance. Meiobenthos of the soft bottom of underground channel is represented by 15 higher taxa with predominance of free-living nematodes and harpacticoids by abundance. Average density of meiobenthos in the channel’s bottom sediments is comparable with similar parameters of its development in open water areas and Sevastopol bays.
In the XIX and XX centuries thickclawed crayfish Astacus pachypus was reported for the Sevastopol area in Crimea. Nowadays significant changes of hydrolological conditions and substrates took place in the only possible locality where a population of this species could exist-inner part of the Sevastopol Bay and the mouth of River Chernaya. Biotopes characteristic for this place in the XIX century were lost. Since the conditions optimal for thick-clawed crayfish in the River Chernaya estuary are currently absent, this species most likely has vanished from the Sevastopol area. РЕЗЮМЕ. В XIX и начале XX веков в Крыму, в районе Севастополя отмечался толстопалый рак Astacus pachypus. К настоящему времени в месте наиболее вероятного обитания этого вида-кутовой части Севастопольской бухты и устья реки Черной произошли значительные изменения гидрологических условий, субстрата и утрата биотопов, характерных для этих мест в прошлом. Поскольку условия, оптимальные для жизни толстопалого рака в эстуарии реки Черной в настоящее время отсутствуют, то с большой долей вероятности можно предположить, что в районе Севастополя этот вид исчез.
The spat of the scallop Flexopecten glaber were collected in cages with the Pacific oyster Crassostrea gigas cultured on a mussel-and-oyster farm (outer roadstead of Sevastopol Bay). For two years they were reared in plastic cages at a depth of 2-3 m. The cages were periodically withdrawn to measure the size and weight parameters of the molluscs: the length (L, mm), height (H, mm), and width (D, mm) of shells and the total live weight (W, g). The correlations among the parameters under study are presented. The changes in the indices of the frontal (D/L) and sagittal (H/L) curvatures, convexity ((H+D)/L) and conditional volume (H×D×L/1000) of the shells in ontogenesis are shown. Upon reaching a shell length of 30-35 mm, the allometry of the volumetric and weight growth of molluscs changed from positive to negative. The largest values of the shell convexity index were registered in thesame length range. A conclusion about the interval-type growth of F. glaber in linear size and weight is made. It is suggested that the optimal strategy of shell formation in F. glaber in ontogenesis implies the ripening and the first reproduction of the molluscs occurring at the highest volumetric characteristics of the shell. The relationships for the linear size and weight growth ofF. glaber in the first two years of life are obtained. It is concluded that the scallop F. glaber should be considered as a possible element for the diversification of the existing aquaculture of molluscs (mussels and oysters) off the coast of Crimea.
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