Marine Biological Journal最新文献

{"title":"Some peculiarities in vertical distribution of metazoan microzooplankton in the Black Sea in spring","authors":"S. Seregin","doi":"10.21072/MBJ.2020.05.4.08","DOIUrl":"https://doi.org/10.21072/MBJ.2020.05.4.08","url":null,"abstract":"Based on material, received in the 84th and 93rd cruises of the RV “Professor Vodyanitsky”, vertical distribution of microplankton fraction of metazooplankton (MM) in the Black Sea in spring was analyzed. A total of 27 stations were examined both in the coastal zone and in the deep sea. The 10-L bottles of the CTD probes “Mark-III Neil Brown” and “Sea Bird 911” were used to collect 4–6 L of water from 4–11 horizons of the water column. The samples obtained were concentrated by the reverse filtration through the plankton net with the mesh size of 10 µm. Quantitative and systematic analysis of all samples was carried out totally in the Bogorov chamber using an MBS-9 stereo microscope. The main factors determining nature of the distribution are MM species composition, physical structure of the water column, and hydrodynamic processes affecting its stability/instability. Nauplii of Black Sea Copepoda and veligers of Bivalvia were the most numerous systematic groups in “spring” MM. Mollusc veligers determined abundance maxima in the lower layers of shallow water habitats, while copepods prevailed over large depths and determined total abundance peaks in the upper and middle water layers. Daily time series experiment showed that advective hydrodynamic processes can significantly affect MM vertical distribution, changing physical structure of the water column. For some species, in most cases, a correlation of their distribution with vertical profiles of temperature and salinity was revealed, which rarely manifested at total MM abundance level. A comparison of two spring seasons (2016 and 2017) showed the relationship between vertical distribution of MM abundance and temperature to be more pronounced in cases of low temperature. A change in the sign of correlation with temperature was detected during spring season for Oithona similis: an initially cold-loving species of Black Sea copepods. This revealed in a more superficial distribution of the maxima abundance of this species at lower seasonal temperatures, which could reflect a shift in temperature optimum for the species population and play the role of an adaptive reaction in conditions of seasonal changes in sea thermal characteristics.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87847340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heavy metals in surface water of the Atlantic sector of the Antarctic during the 79th cruise of the research vessel “Akademik Mstislav Keldysh”","authors":"N. Mirzoeva, N. Tereshchenko, A. Paraskiv, V. Proskurnin, E. Morozov","doi":"10.21072/MBJ.2020.05.4.05","DOIUrl":"https://doi.org/10.21072/MBJ.2020.05.4.05","url":null,"abstract":"Relevance of monitoring heavy metals content in the water of the Atlantic sector of the Antarctic is due to the need for a current assessment of quality of the marine environment for making responsible decisions on the conservation of marine living resources in this unique area of the World Ocean. The aim of the study was to obtain new data on levels and spatial distribution of concentrations of trace elements, mainly heavy metals, in surface water. Sampling of surface seawater was carried out during the Antarctic expedition of the 79th cruise of the RV “Akademik Mstislav Keldysh” at 21 stations in the area of the Drake Passage, the Bransfield Strait, and the Antarctic Sound, as well as in Weddell and Scotia seas. Extracting and concentrating of dissolved form of 13 trace elements (Be, Se, Sb, Tl, V, Pb, Cd, Cu, Zn, Ni, Mo, Co, and Fe) were performed using sodium diethyldithiocarbamate and carbon tetrachloride (CCl4). The elements were measured by mass spectrometry. Among all trace elements content, only Mo concentration in seawater at 9 stations, located in the Drake Passage, the Bransfield Strait, northern Weddell Sea, and off the southern coast of Tierra del Fuego Island, exceeded 1.2–2.8 times maximum permissible concentration of trace elements in fishery water bodies of the Russian Federation (MPCF). According to international regulatory legal acts, such as “Dutch sheets”, there were single cases of exceeding MPC (maximum permissible concentration under short-term exposure) for Cd and Zn, as well as exceeding TV (target value under chronic exposure) for Cu, Pb, Cd, Zn, Se, and Co at several stations. The research has shown as follows: despite limited anthropogenic pressure on this area of the Southern Ocean, in seawater of some regions of the Atlantic sector of the Antarctic, increased concentrations of several trace elements, inter alia heavy metals, are recorded. Further study of the sources of trace elements intake and the peculiarities of their distribution in seawater of the Atlantic sector of the Antarctic is required in order to account for ongoing processes, take measures for rational management, and provide ecologically acceptable use of natural resources in the Antarctic.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87443077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of 24-hour hypoxia on hemocyte functions of Anadara kagoshimensis (Tokunaga, 1906)","authors":"E. Kladchenko, A. Y. Andreyeva, T. A. Kukhareva, V. Rychkova, A. Soldatov","doi":"10.21072/MBJ.2020.05.4.03","DOIUrl":"https://doi.org/10.21072/MBJ.2020.05.4.03","url":null,"abstract":"Shellfish farms are usually located in coastal areas, where molluscs can be exposed to hypoxia. Cultivating at low oxygen levels causes general disruptions of growth rate, outbreaks of diseases, and mollusc mortality. Impact of short-term hypoxia on hemocyte functions of ark clam (Anadara kagoshimensis) was investigated by flow cytometry. A control group was incubated at 6.7–6.8 mg O2·L−1, an experimental one – at 0.4–0.5 mg O2·L−1. Exposition lasted for 24 hours. Hypoxia was created by blowing seawater in shellfish tanks with nitrogen gas. In ark clam hemolymph, 2 groups of hemocytes were identified on the basis of arbitrary size and arbitrary granularity: granulocytes (erythrocytes) and agranulocytes (amebocytes). Erythrocytes were the predominant cell type in A. kagoshimensis hemolymph, amounting for more than 90 %. No significant changes in cellular composition of ark clam hemolymph were observed. The production of reactive oxygen species and hemocyte mortality in the experimental group also remained at control level. The results of this work indicate ark clam tolerance to hypoxia.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"85 1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89333519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genotyping of Black Sea trematodes of the family Opecoelidae by mitochondrial markers","authors":"A. V. Katokhin, Y. Kornyychuk","doi":"10.21072/mbj.2020.05.4.02","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.4.02","url":null,"abstract":"Opecoelidae Ozaki, 1925 (Trematoda: Opecoeloidea) is the biggest trematode family in the Black Sea in terms of species and genera number. Maritae of the most common Black Sea Opecoelidae trematodes are well described morphologically; nevertheless, information on their genomes structure is sketchy, and data on mitochondrial genomes are absent. The aim was to study the structure of mitochondrial genome fragments of Black Sea trematode species: Cainocreadium flesi Korniychuk & Gaevskaya, 2000, Gaevskajatrema perezi (Mathias, 1926) Gibson & Bray, 1982, and Helicometra fasciata (Rudolphi, 1819) Odhner, 1902. Sequences were made for CO1 (the cytochrome c oxidase subunit I) and 16S mitochondrial genes. To amplify CO1 gene fragment of Cainocreadium and Helicometra trematodes, primers were developed. Phylogenetic relationships within the analyzed part of the Opecoelidae family were reconstructed on the basis of our data and the corresponding GenBank data by the Maximum Likelihood estimation and the MEGA X programme. To root the phylogenetic trees, the corresponding sequences of the closely related trematode Brachycladium goliath (Brachycladioidea: Brachycladiidae) were used. For the first time, nucleotide sequences of CO1 and 16S mitochondrial genes fragments of Black Sea trematodes C. flesi, G. perezi, and H. fasciata from different definitive fish hosts were determined and deposited in the GenBank. In case of C. flesi, no host-specific lines were found in the structure of CO1 mitochondrial gene fragment, but high CO1 nucleotide diversity was noted. Black Sea H. fasciata, parasitizing peacock wrasse, Symphodus tinca, were revealed to be a host-specific CO1 haplogroup; its taxonomical status requires further clarification, and ecological and genetic studies of the putative H. fasciata species complex from different water areas are needed. No host-specific genetic lines were found when analyzing the sequences of H. fasciata 16S rRNA mitochondrial gene fragment. No significant differences in 16S fragment were registered between G. perezi trematodes from different Black Sea definitive hosts; however, the intraspecific 16S nucleotide diversity was rather high.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78634812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biogeochemical characteristics of shallow methane seeps of Crimean coastal areas in comparison with deep-sea seeps of the Black Sea","authors":"T. V. Malakhova, V. Egorov, L. Malakhova, Yu. G. Artemov, N. Pimenov","doi":"10.21072/mbj.2020.05.4.04","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.4.04","url":null,"abstract":"Methane gas bubble emissions (seeps) are widespread phenomenon in the World Ocean, inter alia in Black Sea basin. The relevance of the research of methane seeps is due to their important role as a source of methane – greenhouse and environment-forming gas – for water column and atmosphere. The article presents a comparative analysis of the data from our biogeochemical 10-year studies of shallow gas seeps of the Crimean Peninsula and data on deep-sea gas seeps of the Black Sea. During 10-year period, apart from carrying out hydroacoustic research, the following parameters were determined: bubble gas component composition, methane carbon isotopic composition, microbial community structure of bacterial mats, covering gas bubble emission sites, and gas fluxes from separate seeps. During long-term monitoring, 14 separate gas bubble emission sites were detected and described in Crimean coastal areas; they were located from Cape Tarkhankut in the west of the peninsula to the Dvuyakornaya Bay in the southeast. Crimean coastal seeps were mostly of biogenic origin, with a seasonal type of gas bubble emission. Laspi Bay seeps were classified as emissions of deep gas of thermocatalytic genesis. A significant variation was recorded in values of isotopic composition of methane carbon δ13C-CH4 of bubble gas in coastal shallow areas (−94…−34 ‰), which indicates different conditions for bubble gas generation and maturation in seabed sediments. Similar to deep-sea seeps, coastal gas bubble emissions were accompanied by bacterial mats of diverse structure, with different dominating species. As shown, formation of stable bacterial biomass, usually consisting of sulfide- and sulfur-oxidizing bacteria, requires a fluid flux of reduced dissolved gases, while pointwise bubble gas discharge does not provide sufficient concentration gradients and can mechanically disrupt community structure. Various methods were used to estimate the size spectra of bubbles, as well as fluxes from separate seeps. Gas flux values varied from 1.8 L·day−1 (the Martynova Bay) to 40 L·day−1 (the Laspi Bay). The environment-forming effects, related to gas bubble emission in coastal areas, are discussed: effect of seeps on oxygen conditions in seabed sediments and in water column above gas emission sites, vertical water mixing due to gas lift effect, and fluid discharge at gas emission sites.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90250251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"137Cs concentration in surface waters of Far Eastern seas: Results of expeditionary research in 2018","authors":"O. Miroshnichenko, A. Paraskiv","doi":"10.21072/mbj.2020.05.3.05","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.3.05","url":null,"abstract":"Based on the results of expeditionary research carried out during the 82nd cruise of the RV “Akademik M. A. Lavrentyev” (01.06.2018–20.07.2018), the assessment of current levels of concentration activity of technogenic radionuclide 137Cs in surface waters of Far Eastern seas is given. The studies were carried out in the northwestern part of the Sea of Japan, the southern part of the Sea of Okhotsk, the coastal waters of the Pacific Ocean near the Kamchatka Peninsula, and the western part of the Bering Sea. Activity of 137Cs in seawater samples was determined by sorption method using two series-connected adsorbers with subsequent measurement of 137Cs content via its gamma-emitting daughter radionuclide 137mBa. Sorption efficiency was assessed by the difference in activity on the first and second adsorbers. A comparative analysis of contamination levels of water areas studied was made. It was revealed that 137Cs volumetric activity in surface water of the Sea of Japan varied from (2.9 ± 0.1) to (5.1 ± 0.3) Bq·m−3, in the Sea of Okhotsk – from (1.8 ± 0.1) to (2.3 ± 0.1) Bq·m−3, and in the Bering Sea – from (1.7 ± 0.1) to (3.1 ± 0.1) Bq·m−3. The maximum 137Cs concentrations were registered in the Sea of Japan, which might be due to its isolation from other water areas and presence of secondary sources of radionuclide intake. In general, contamination of adjacent water areas is insignificant, and fluctuations in concentrations occur within technogenic isotopes global background in the marginal seas of the Pacific Ocean.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78096265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of the G. G. Polikarpov conceptual model of chronic action zonality of ionizing irradiation doze rates to biosphere objects in applied hydrobiology","authors":"Н. Н. Терещенко","doi":"10.21072/mbj.2020.05.3.08","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.3.08","url":null,"abstract":"Evolution of the approach to assessing ionizing radiation effects on living organisms is briefly discussed in this paper. Using the example of Black Sea hydrobionts, possibility of applying the G. G. Polikarpov conceptual radiochemoecological model of chronic action zonality of ionizing irradiation dose rates in nature to assess ecological exposure of technogenic radioisotopes ionizing radiation on aquatic biota was shown. In applied hydrobiology, this model can serve as the basis for a complex approach in assessing aquatic biota ecological state and its prediction for a wide range of 239,240Pu activity concentration in seawater. The necessity of combined use of biogeochemical and equidosimetric indicators of radionuclide behavior in a water area is emphasized. In particular, for predictive dosimetric assessments, it is important to take into account quantitative characteristics of accumulative ability of Black Sea hydrobionts and a type of radioelement biogeochemical behavior, reflecting peculiarities of plutonium biogeochemical migration in a marine ecosystem.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74552181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mercury accumulation in suspended matter of foam and water of the Black Sea","authors":"A. Stetsiuk","doi":"10.21072/mbj.2020.05.3.07","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.3.07","url":null,"abstract":"The ability of suspended matter to concentrate mercury may be the prevailing factor in Black Sea purification. As a result of sedimentation, suspended particles transport pollution from the surface layer of the water column and, as a consequence, can deposit them in bottom sediments, thus participating in self-purification of marine area. Suspended matter, as a dispersed phase of an aqueous medium, considered as a heterogeneous dispersed system, can be more saturated with mercury than water itself, as a dispersion medium. In this work, contribution of dissolved and suspended forms of mercury to its total content was determined, and concentrating ability of suspended matter relative to mercury, which affects biogeochemical self-purification of waters from mercury, was estimated. All water samples were separated into filtrate and suspension by filtration through nucleopore filters with a pore diameter of 0.45 μm. Measurements of mercury concentration were carried out using a Hiranuma-1 analyzer by the method of atomic absorption spectrophotometry. Concentration of dissolved mercury in water was determined per liter, while in suspended matter – per liter and per gram of dry weight. Prevalence of dissolved form of mercury was revealed regardless of the season, with its percentage varying from 66.3 to 85.8 % of total mercury concentration. Average content of suspended form varied in the range of 14.2–33.7 % of its total form. Values of the dry weight of suspended matter (mss) varied from 0.1 to 15.0 mg·L−1 over the entire period studied, and an accumulation coefficient of mercury in suspended matter (Kss) varied from n·10³ to n·107. Significant contribution of suspended form of mercury in sea foam to its total content in stormy weather was established. With dry weight of suspended matter in seawater reaching 9.6 mg·L−1, the concentration of dissolved form of mercury reached 55 ng·L−1, and the concentration of suspended one reached 20 ng·L−1. In sea foam, the concentration of suspended sedimentary matter was of 895.2 mg·L−1; mercury concentration reached 200 ng·L−1 in dissolved form and 260 ng·L−1 in suspended one. Total mercury concentration in sea foam in this case exceeded the threshold limit value (100 ng·L−1) for seawater. The accumulation coefficient of mercury in suspended matter (Kss) was 3.8·104 for seawater and 1.5·103 for foam. Such distribution of mercury in sea suspension, foam, and water, as well as Kss values obtained, may indicate high significance of suspended matter in self-purification of marine area. At a low mercury content in water, the concentrating ability of suspended matter, characterized by relatively high values of its mercury accumulation coefficient, becomes a very significant factor in the sedimentation self-purification of waters from mercury; however, with an increase in water pollution with mercury, the effect of this factor decreases.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88395012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of mussel Mytilus galloprovincialis exometabolites on R-phycoerythrin concentration in red alga Gelidium spinosum when grown in polyculture","authors":"B. N. Belyaev, N. Beregovaya","doi":"10.21072/mbj.2020.05.2.02","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.2.02","url":null,"abstract":"To increase R-phycoerythrin concentration in red Black Sea alga Gelidium spinosum (S. G. Gmelin) P. C. Silva, 1996 (Rhodophyta), it was cultivated in laboratory conditions in polyculture microalga Tetraselmis viridis – mussel Mytilus galloprovincialis – Gelidium; the results of the study are presented. The positive effect of mussel exometabolites on R-phycoerythrin concentration in Gelidium 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 Gelidium using the polyculture method. As a material, Gelidium 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 Gelidium. 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 Gelidium / 50–60 g of two-year-old mussels / 0.4–0.6 g of microalga wet weight.","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"560 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72505803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of low frequency rectangular electric pulses on Trichoplax (Placozoa)","authors":"A. Kuznetsov, O. Kuleshova, A. Pronozin, O. Krivenko, O. Zavyalova","doi":"10.21072/mbj.2020.05.2.05","DOIUrl":"https://doi.org/10.21072/mbj.2020.05.2.05","url":null,"abstract":"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 Trichoplax organisms as a possible test laboratory model. Three Placozoa strains, such as Trichoplax adhaerens (H1), Trichoplax sp. (H2), and Hoilungia hongkongensis (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 Trichoplax. Experimental animals were investigated under a stereo microscope and stimulated by current-carrying electrodes placed close to a Trichoplax body. Variations in behavior and morphological characteristics of Trichoplax 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 Trichoplax. Direction of motion was used as a characteristic feature. Trichoplax 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 Trichoplax plate, and finally to Trichoplax folding and detach from the substrate. Additional experiments on Trichoplax 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 Tri","PeriodicalId":18191,"journal":{"name":"Marine Biological Journal","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81174268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}