Marine Biological Journal <p>Морской биологический журнал Marine Biological Journal.</p> <div><em><strong>Launched in February 2016.</strong></em></div> <div><em><strong>Certificates of registration:</strong></em></div> <div>print version: <a href="" target="_blank" rel="noopener">ПИ № ФС 77 - 76872 of 24.09.2019</a>,</div> <div>online version: <a href="" target="_blank" rel="noopener">ЭЛ № ФС 77 - 76873 of 24.09.2019</a>.</div> <div> <div><em><strong>Founder:</strong></em></div> <div>A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS.</div> </div> <div><em><strong>Publishers</strong></em>:</div> <div><a href="" target="_blank" rel="noopener">A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS</a>,</div> <div><a href="" target="_blank" rel="noopener">Zoological Institute of RAS</a>.</div> <div>ISSN 2499-9768 print, ISSN 2499-9776 online.</div> <div><em><strong>Languages:&nbsp;</strong></em>Russian, English.</div> <div><em><strong>Periodicity:</strong></em> four issues a year.</div> <div>&nbsp;</div> <div><strong>Authors do not need to pay an article-processing charge.</strong></div> <div>The payment of royalties is not provided.</div> <div>&nbsp;</div> <div>Author recieves one copy of printed version of the journal as well as .pdf file.</div> <div>&nbsp;</div> <div> <div class="siteorigin-widget-tinymce textwidget"> <p>Marine Biological Journal is an open access, peer reviewed (double-blind) journal. The journal publishes original&nbsp;articles as well as reviews and brief reports and notes focused on new data of theoretical and experimental research in the fields of marine biology, diversity of marine organisms and their populations and communities, patterns of distribution of animals and plants in the World Ocean, the results of a comprehensive studies of marine and oceanic ecosystems, anthropogenic impact on marine organisms and on the ecosystems.</p> <p>Intended audience: biologists, hydrobiologists, ecologists, radiobiologists, biophysicists, oceanologists, geographers, scientists of other related specialties, graduate students, and students of relevant scientific profiles.</p> <p>The subscription index in the “<a title="Russian Press MBJ" href="" target="_blank" rel="noopener">Russian Press</a>” catalogue is Е38872.</p> </div> </div> en-US (Корнийчук Юлия Михайловна \ Kornyychuk Yulia Mikhailovna) (Баяндин Алексей Сергеевич) Tue, 30 Jun 2020 00:00:00 +0000 OJS 60 Production characteristics of the copepods Arctodiaptomus salinus and Calanipeda aquaedulcis fed with a mixture of microalgae Dinophyceae and Prymnesiophyceae <p>The ubiquitous copepod species <em>Arctodiaptomus salinus</em> (Daday, 1885) and <em>Calanipeda aquaedulcis</em> (Krichagin, 1873) are important components of food chains of numerous fresh- and saltwater areas. These copepods are suitable for feeding larvae of both marine and freshwater fish species; however, influence of nutrition on the production characteristics of these species is not well understood. Previously we determined that monocultures of microalgae Dinophyceae and Prymnesiophyceae are optimal feeding objects for egg production by females of <em>A. salinus</em> and <em>C. aquaedulcis</em>, survival rate, and development time of these copepods throughout ontogenesis. The aim of this work was to determine the production characteristics of copepods <em>A. salinus</em> and <em>C. aquaedulcis</em> under optimal temperature conditions depending on the model of the feeding with a mixture of microalgae Dinophyceae and Prymnesiophyceae. The highest survival rates of <em>A. salinus</em> from the naupliar stage to the adult one (93–95 %) were observed when copepods were fed with a monoculture of microalga <em>Isochrysis galbana</em> (Parke, 1949) or a mixture <em>I. galbana</em> + <em>Prorocentrum cordatum</em> (Ostenfeld) J. D. Dodge, 1975; the shortest development time (19 days) – when copepods were fed with a mixture of three microalgae <em>I. galbana</em> + <em>P. cordatum</em> + <em>Prorocentrum micans</em> (Ehrenberg, 1834). The shortest development time of <em>C. aquaedulcis</em> from the naupliar stage to the adult one (13 days) was observed when copepods were fed with a mixture of microalgae <em>I. galbana</em> + <em>P. cordatum</em>. The shortest duration of the naupliar stage of development of both copepod species was observed when their diet included <em>I. galbana</em> as a monoculture or one of mixture components. During the copepodit stage, the pattern remains the same, only with <em>P. cordatum</em>. The maximum absolute fecundity of <em>C. aquaedulcis</em> reached 24 eggs per female (<em>I. galbana</em>), of <em>A. salinus</em> – 16 eggs per female (<em>P. cordatum</em>). Egg hatching of <em>C. aquaedulcis</em> when being fed with both monocultures of microalgae <em>P. cordatum</em> and <em>I. galbana</em> and with their mixture reached 100 %. The highest egg hatching rate for <em>A. salinus</em> was reached only when copepod females were fed with a mixture of microalgae <em>I. galbana</em> + <em>P. micans</em>.</p> L. O. Aganesova Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Influence of mussel Mytilus galloprovincialis exometabolites on R-phycoerythrin concentration in red alga Gelidium spinosum when grown in polyculture <p>To increase R-phycoerythrin concentration in red Black Sea alga <em>Gelidium spinosum</em> (S. G. Gmelin) P. C. Silva, 1996 (Rhodophyta), it was cultivated in laboratory conditions in polyculture microalga <em>Tetraselmis viridis</em> – mussel <em>Mytilus galloprovincialis</em> – <em>Gelidium</em>; the results of the study are presented. The positive effect of mussel exometabolites on R-phycoerythrin concentration in <em>Gelidium</em> in polyculture is described. The relevance of the work is determined by the value of R-phycoerythrin, which is used as a powerful antioxidant, as well as a marker in cytometry and microscopy. The aim of the study is to increase R-phycoerythrin concentration in <em>Gelidium</em> using the polyculture method. As a material, <em>Gelidium</em> from the fouling of rocks and coastal protection structures of Karantinnaya Bay (Sevastopol) was used; it was cultivated in a laboratory installation with eight working volumes, four of which contained mussels. Mussel decontamination, supplemented with mineral salts and biogens, was used as a nutrient medium for <em>Gelidium</em>. The combination of mussel exometabolites with previously developed nutrient medium, based on Black Sea water and enriched with nutrients and mineral salts, results in an increase in R-phycoerythrin concentration by more than 2 times, while the addition of exometabolites to pure filtered seawater increases it maximum by 35 %. Approximate ratios of polyculture elements in 1.5-L volumes, allowing to achieve the desired results in 2 weeks, are as follows: 2 g of <em>Gelidium</em> / 50–60 g of two-year-old mussels / 0.4–0.6 g of microalga wet weight.</p> B. N. Belyaev, N. M. Beregovaya Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Barents Sea megabenthos: Spatial and temporal distribution and production <p>This long-term observation of the faunal composition within the Barents Sea provides a benchmark for monitoring community changes caused by oceanographic variability, fishery activities, and crab predators (<em>Chionoecetes opilio</em>, <em>Paralithodes camtschaticus</em>), whose populations have been rapidly growing and spreading in recent years. In the Arctic systems, megabenthic communities comprise a significant part of benthic biomass and play an important role in carbon cycling on continental shelves. The gradual accumulation of knowledge on megabenthos may make it possible to assess their role in the ecosystem and ultimately contribute to a more rational management of the Barents Sea resources. This article represents an important series of long-term megabenthic observations in the Barents Sea. The main goal of our research is to identify spatial patterns and temporal trends in the megabenthic part of communities, including changes in the biomass and production values. As a part of the joint Norwegian-Russian ecosystem surveys, benthic experts have been identifying the invertebrates (megafauna) collected by bottom trawls during annual assessments of commercial stocks, such as Atlantic cod (<em>Gadus morhua</em>) and northern shrimp (<em>Pandalus borealis</em>). The sampling equipment used was a Campelen 1800 bottom trawl, rigged with rockhopper ground gear and towed on double warps, and standardized to a fixed sampling effort (equivalent to a towing distance of 0.75 nautical miles (nm), or 1.4 km). The processing of the biological material was conducted in accordance with standardized procedures, following the retrieval of each trawl. This work represents data from 5016 stations from 2005 to 2017, with a total sampled biomass of 238.4 tons and 14.9 million individual organisms. In total, 694 megabenthic species (1058 taxa) have been recorded, with the greatest diversity observed in the depth range of 100–400 m, while the largest mean catches were taken between depths of 600–800 m. The biomass (B) and production (P) values of the benthic megafauna were approximately stable during the 9 years of investigation, although there was a decreasing trend after 2014. The annual production P/B ratio of megabenthos was calculated to be at 0.3. The distribution, contribution to production, and gross biomass values of the megabenthos had been underestimated in the previous studies of zoobenthos. The results from this research show that, in the current warm period, the majority of the Barents Sea is in an intermediate state between the Arctic and boreal regions due to the wide distribution of boreal species toward the north. The dynamics of the mean biogeographical index (the border between areas of the dominance of boreal and Arctic species) within the central-southern part of the Barents Sea suggests that a large part of the area can be characterized as predominantly boreal intermediate since 2013.</p> D. V. Zakharov, L. L. Jørgensen, I. E. Manushin, N. A. Strelkova Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Fatty acid composition in trochophores of mussel Mytilus galloprovincialis grown under contamination with polychlorinated biphenyls <p>Status of <em>Mytilus galloprovincialis</em> populations in the natural habitat is known to directly depend on development of Black Sea mussel at all its stages, including initial stages of larval ontogenesis, which are very sensitive to environmental pollution. Organic pollutants adversely affect mussel larvae by inhibiting their growth and development. Patterns of mussel reproduction are well studied, which makes it possible to obtain larvae from artificially fertilized eggs of this mollusc species in controlled laboratory conditions. In this work, the fatty acid composition of <em>M. galloprovincialis</em> larvae at the trochophore stage on the 3<sup>rd</sup> day in the control experiment and under artificial contamination with polychlorinated biphenyls (PCBs) in different concentrations is studied for the first time. The fatty acid composition of total lipids in the biomass of larvae obtained on the 3<sup>rd</sup> day of the experiment was studied by means of gas chromatography – mass spectrometry. Totally, 14 fatty acids were identified in the samples; 59 % of them were saturated fatty acids, 24 % were monounsaturated fatty acids, and 17 % were polyunsaturated fatty acids. Statistical analysis was performed using Statistical Toolbox of MATLAB software (version 8.2). The totals of monounsaturated and polyunsaturated fatty acids significantly differed in lipids of <em>M. galloprovincialis</em> trochophores in the experiment with different PCB concentrations. The totals of saturated fatty acids did not significantly differ. The major saturated fatty acids in all mussel trochophores studied were palmitic (C16:0) and stearic (C18:0) acids. Their concentration did not significantly change under the exposure to PCBs. The main monounsaturated fatty acids were oleic (C18:1ω9), palmitoleic (C16:1ω7), and vaccenic (C18:1ω7) acids. The fraction of monounsaturated fatty acids was twice as low when exposed to the PCB concentrations 0.1 and 1.0 μg·L<sup>−1</sup>. However, when the PCB concentration was 10 μg·L<sup>−1</sup>, the total of these acids did not differ from the control. Among polyunsaturated fatty acids having biological essentiality, it was possible to identify arachidonic (C20:4ω6), eicosapentaenoic (C20:5ω3), and docosahexaenoic (C22:6ω3) acids. The total fraction of omega-3 and omega-6 acids in mussel larvae in the control did not exceed 12.8 %. With an increase of the PCB concentration in the growth medium 0.1 to 1.0 μg·L<sup>−1</sup>, the fraction of polyunsaturated fatty acids increased 2.5-fold. At the PCB concentration 10 μg·L<sup>−1</sup> and in the sample with pure acetone added, the total fraction of polyunsaturated fatty acids was comparable with that in the control. The results of the study indicate that fatty acid response is the highest when the medium is exposed to the PCB concentrations ranging 0.1 to 1.0 μg·L<sup>−1</sup>. At the PCB concentrations equal to 10 μg·L<sup>−1</sup> or higher, biochemical processes in larvae seem to slow down. The results of this study will contribute to a better understanding of biochemical rearrangements that allow molluscs at larval developmental stages to adapt to environmental pollution with organic xenobiotics.</p> L. L. Kapranova, L. V. Malakhova, M. V. Nekhoroshev, V. V. Lobko, V. I. Ryabushko Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Effects of low frequency rectangular electric pulses on Trichoplax (Placozoa) <p>The effect of extremely low frequency electric and magnetic fields (ELF-EMF) on plants and animals including humans is quite a contentious issue. Little is known about ELF-EMF effect on hydrobionts, too. We studied the effect of square voltage waves of various amplitude, duration, and duty cycle, passed through seawater, on <em>Trichoplax</em> organisms as a possible test laboratory model. Three Placozoa strains, such as <em>Trichoplax adhaerens</em> (H1), <em>Trichoplax</em> sp. (H2), and <em>Hoilungia hongkongensis</em> (H13), were used in experiments. They were picked at the stationary growth phase. Arduino Uno electronics platform was used to generate a sequence of rectangular pulses of given duration and duty cycle with a frequency up to 2 kHz. Average voltage up to 500 mV was regulated by voltage divider circuit. Amlodipine, an inhibitor of calcium channel activity, was used to check the specificity of electrical pulse effect on voltage-gated calcium channels in <em>Trichoplax</em>. Experimental animals were investigated under a stereo microscope and stimulated by current-carrying electrodes placed close to a <em>Trichoplax</em> body. Variations in behavior and morphological characteristics of <em>Trichoplax</em> plate were studied. Stimulating and suppressing effects were identified. Experimental observations were recorded using photo and video techniques. Motion trajectories of individual animals were tracked. Increasing voltage pulses with fixed frequency of 20 Hz caused H2 haplotype individuals to leave “electrode zone” within several minutes at a voltage of 25 mV. They lost mobility in proportion to voltage rise and were paralyzed at a voltage of 500 mV. Therefore, a voltage of 50 mV was used in further experiments. An animal had more chance to move in various directions in experiments with two electrodes located on one side instead of both sides of <em>Trichoplax</em>. Direction of motion was used as a characteristic feature. <em>Trichoplax</em> were observed to migrate to areas with low density of electric field lines, which are far from electrodes or behind them. Animals from old culture were less sensitive to electrical stimulus. H2 strain was more reactive than H1 strain and especially than H13 strain; it demonstrated stronger physiological responses at frequencies of 2 Hz and 2 kHz with a voltage of 50 mV. Motion patterns and animal morphology depended on the duration of rectangular stimulation pulses, their number, amplitude, and frequency. Effects observed varied over a wide range: from direct or stochastic migration of animals to the anode or the cathode or away from it to their immobility, an increase of optical density around and in the middle of <em>Trichoplax</em> plate, and finally to <em>Trichoplax</em> folding and detach from the substrate. Additional experiments on <em>Trichoplax</em> sp. H2 with pulse duration of 35 ms and pulse delay of 1 ms to 10 s showed that the fraction of paralyzed animals increased up to 80 % with minimum delay. Nevertheless, in the presence of amlodipine with a concentration of 25 nM, almost all <em>Trichoplax</em> remained fast-moving for several minutes despite exposure to voltage waves. Experimental animals showed a total discoordination of motion and could not leave an “electrode trap”, when amlodipine with a concentration of 250 nM was used. Further, <em>Trichoplax</em> plate became rigid, which appeared in animal shape invariability during motion. Finally, amlodipine with a concentration of 50 μM caused a rapid folding of animal plate-like body into a pan in the ventral-dorsal direction and subsequent dissociation of <em>Trichoplax</em> plate into individual cells. In general, the electrical exposure applied demonstrated a cumulative but a reversible physiological effect, which, as expected, is associated with activity of voltage-gated calcium channels. Amlodipine at high concentration (50 μM) caused <em>Trichoplax</em> disintegration; at moderate concentration (250 nM), it disrupted the propagation of activation waves that led to discoordination of animal motion; at low concentration (25 nM), it prevented an electric shock.</p> A. V. Kuznetsov, O. N. Kuleshova, A. Yu. Pronozin, O. V. Krivenko, O. S. Zavyalova Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Influence of invader ctenophores on bioluminescence variability off the coast of Western Crimea <p>In the second half of the XX century, Black Sea ecosystem has undergone significant changes: a number of storm winds and upwellings decreased, precipitation abundance increased, coastal waters salinity decreased, temperature increased; moreover, ctenophores invaded. As a result, in the late 1980s, Black Sea pelagic ecosystem abruptly got restructured. This research is based on the studies performed in 1965–1966 and 2007–2012 near Sevastopol (Western Crimea) using the remote sensing data. Analysis of satellite data over the past 20 years showed the presence of positive dynamics in surface water temperature in Sevastopol water area. In the mid-1960s, the annual bioluminescence was characterized by seasonal peaks of dinophytes luminescence. In recent years, this rhythm has changed due to ctenophores invasion. The increase in <em>Mnemiopsis leidyi</em> abundance leads to a decrease in bioluminescence of luminous microalgae being consumed by these ctenophores. Due to <em>Beroe ovata</em> invasion and reproduction, <em>M. leidyi</em> biomass decreased; as a result, bioluminescence increased.</p> A. V. Melnik, V. V. Melnikov, L. A. Melnik, O. V. Mashukova Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Estimation of cell distribution heterogeneity at toxicological experiments with clonal cultures of benthic diatoms <p>An increase in anthropogenic pressure on coastal water areas requires regular monitoring of marine ecosystems. The appropriate bioindicators for indirect assessment of the quality of the near-shore environment are benthic diatom algae, which are a key element of coastal communities and are highly sensitive to environmental impact. Changes in the development of diatoms under the influence of various toxicants may be used as relevant tool for monitoring of marine environment quality. However, scientific and methodological approaches to application of benthic diatom algae as test objects remain unstudied. One of the important methodological problems is the assessment of the significance of the samples in experimental vessels when counting cells abundance at different stages of toxicological test. The study is focused on assessment of the statistical significance of the equality of the initial mean number of cells of clonal culture inoculum placed into each of the replicates, as well as the statistical uniformity of cell distribution over the entire bottom area of Petri dishes. We used clonal cultures of three benthic diatom species belonging to different classes of Bacillariophyta: <em>Thalassiosira</em> <em>excentrica</em> Cleve, 1903 (Coscinodiscophycea), <em>Ardissonea crystallina</em> (C. Agardh) Grunow, 1880 (Fragilariophyceae), and <em>Pleurosigma</em> <em>aestuarii</em> (Bréb. in Kütz.) W. Smith, 1853 (Bacillariophyceae). They significantly differ in valve morphology and life history (floating in water mass, attached to substrate, and motile). The results of statistical comparison of cell number variability in the experiment for all studied species confirmed the absence of significant differences between the mean values of the tested parameter at a standard significance level (0.05). It was shown that despite specific differences in cell growth rate during the experiment, the variability in cell number in the microscope viewing fields varies irregularly. The highest value of the variability coefficient was observed on the 5<sup>th</sup> day for the small-sized species <em>T. excentrica</em> (<em>Cv</em> = 42…55 %), and the lowest variability – for the large-cell species <em>A. crystallina</em> (<em>Cv</em> = 27…31 %). The absence of significant differences in cell number between three replicates (for each species) was established both during the initial placing of inoculum into the dishes and on the following days of the experiment. The conclusion is applicable for each of diatom species studied, which allows to consider all replicates as subsamples of the replicate sample and to average the results obtained at different stages of the toxicological experiment. The uniformity of cell distribution throughout experimental dishes bottom, which does not depend on species and absolute cell number, was statistically proven. The results obtained allow to statistically reliably estimate the changes in cell number at different stages of toxicological experiment according to replicate sampling, based on cell counting in a limited number of viewing fields.</p> A. N. Petrov, E. L. Nevrova Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Features of formation of colonial settlements of marine benthic diatoms on the surface of synthetic polymer <p>The topic of interactions between plastic and natural communities is now more relevant than ever before. Gradual accumulation of artificial polymer products and their fragments in the natural environment has reached a level at which it is already impossible to ignore the affect of these materials on living organisms. First and foremost, microorganism colonies inhabiting different biotopes, both aquatic and terrestrial, have been affected. These species are at the front-end of interaction with plastic, including those present in marine ecosystems. Nevertheless, in order to understand these processes, it is necessary to take into account several aspects of such interactions: the impact of different types of plastic on microbial community through the release of their decomposed products into the environment, the forms of plastic usage by microorganisms themselves, including mechanisms for surface colonization, as well as possible biodegradation processes of polymers due to the actions of microorganisms. At the same time, types of plastic may differ not only in mechanical strength, but also in their resistance to biodegradation caused by microorganisms. Experiments with surface colonization of types of plastic, which are different in composition and mechanical strength, provide a wide range of results that are not just relevant for understanding modern natural processes involving plastic: these results are also important for application in certain areas of technology development (for example, when creating composite materials). In particular, researches into the forms and mechanisms of sustainable colonization of particularly strong polymers by diatoms from natural communities are of great interest. Due to the fouling of surface of particularly strong synthetic polymers by diatoms, it is possible to form a single diatom-polymeric composite with general properties being already substantially different from those of the polymer itself. For example, when a polymer is fouled with diatoms that are firmly held on its surface due to physiological mechanisms that ensure their reliable fixation, total surface area of the composite increases by 2–3 orders of magnitude compared with this of bare polymer. Such composites and their properties are formed due to mechanisms of substrate colonization used by diatoms from natural marine cenoses – during the transfer of these mechanisms to a new material being prospective for diatom settlement. The practical applications of these composites lie in the sphere of heat and sound insulation, as well as in the field of creating prosthetic tissues for bone operations. In our experiments, we tracked the sequence of development of a stable composite when diatoms colonized the surface of samples of a particularly strong synthetic polymer being resistant to corrosion. In this case, the sample population process took place on the basis of colonies formed in accumulative cultures from the natural marine environment. Samples of ultra-high molecular weight polyethylene (UHMWPE) with a smooth and porous surface structure (with an open cell, bulk porosity up to 80 %) were colonized by diatoms <em>Karayevia amoena</em> (Hust.) Bukht., 2006, <em>Halamphora coffeaeformis</em> (C. Agardh) Levkov, 2009, and <em>Halamphora cymbifera</em> (W. Greg.) Levkov, 2009. These laboratory experiments lasted for three weeks. Accumulative microphyte cultures, on the basis of which the experiments were conducted, were obtained from the Baltic Sea (Baltiysk area, Russia) and the Arabian Sea (Mumbai area, India). The types and stages of development of colonial settlements on various elements of the frontal surface microrelief and in the underlying caverns were studied using a scanning electron microscope on samples subjected to stepwise thermal drying. Individual cells of <em>K. amoena</em>, <em>H. coffeaeformis</em>, and <em>H. cymbifera</em>, their chain-like aggregates, and outstretched colonial settlements occupied varying in degree non-homogeneous microrelief surface elements, forming structures with a thickness of 1–2 layers with an average settlement height of 1–1.3 single specimen height. <em>K. amoena</em> cells were tightly fixed to the polymer substrate using the pore apparatus of the flap of the frustule. Observations using scanning electron microscope revealed shell imprints on the substrate, which were signs of a polymer substrate introduction into hypotheca areoles. The spread mechanisms of diatoms of three mentioned species on various elements of UHMWPE surface were explored, as well as the formation of the characteristic elements of colonial settlements, including for <em>K. amoena</em> – consecutively in the form of “pots” and spheres, by means of interaction with polymer surface and its extension with the increase in the number of tightly attached cells in the colonial settlement.</p> Ph. V. Sapozhnikov, A. I. Salimon, A. M. Korsunsky, O. Yu. Kalinina, F. S. Senatov, E. S. Statnik, Ju. Cvjetinovic Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 Response of Mnemiopsis leidyi larvae to light intensity changes <p>A possible response to light of larvae of Black Sea ctenophore <em>Mnemiopsis leidyi</em> of two age groups (first to fourth day and one-two weeks after hatching) was experimentally studied. The larvae were placed in a Petri dish with seawater, in which two areas (light and dark) were created using a light source and a black opaque background. The number of larvae in each area was recorded for an hour after the start of the experiment. It was found that on average 77 % of the early stage larvae (first to fourth day) migrated to the dark area after an hour. We hypothesized that <em>Mnemiopsis leidyi</em> early stage larvae have negative phototaxis. Similar response of the older larvae (one-two weeks) was not recorded.</p> Iu. S. Baiandina Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 The finding of a rare in the Black Sea polychaete Ctenodrilus serratus (Schmidt, 1857) (Annelida, Cirratulidae) <p>In July 2019, three polychaetae specimens of the genus <em>Ctenodrilus</em> were found in oyster cages on silted oyster shells. The cages from a mussel-and-oyster farm located at the outer roadstead of Sevastopol Bay were suspended at a depth of 6–8 m. The bottom soil under the mussel-and-oyster farm is silted sand, and the depth is of 16 m. During the sampling, water temperature was of +23 °C, and the salinity was of 17.7 ‰. Thus, according to morphological characteristics, polychaetae we found should be classified as <em>Ctenodrilus serratus</em> (Schmidt, 1857). Photographs of alive and fixed polychaetae, chaetae patterns, and a schematic representation of their number by segments are presented. At the beginning of the XX century, a single specimen of this species was found in the Black Sea.</p> E. V. Lisitskaya, N. A. Boltachova Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000 To the anniversary of Academician of the RAS Viktor Egorov <p>This year, Viktor Egorov, IBSS Supervisor, Academician of the Russian Academy of Sciences, D. Sc., Prof., Editor-in-Chief of “Marine Biological Journal”, celebrates the anniversary. He developed the theory of mineral metabolism between marine organisms and the aquatic environment, discovered jet methane gas emissions from the bottom of the Black Sea, and created the basics of the biophysical theory of the ecological capacity of the marine environment in relation to pollutants. Viktor Egorov is the author of more than 360 articles and 6 monographs.</p> Staff of IBSS radiation and chemical biology department Copyright (c) 2020 A. O. Kovalevsky Institute of Biology of the Southern Seas of RAS Tue, 30 Jun 2020 00:00:00 +0000