Now showing items 1-20 of 38681

    • Phospholipids profile of the edible clams flesh during different frying processes

      Bejaoui, Safa; Ghribi, F.; Telahigue, Khaoula; Chetoui, I.; Rabeh, I.; Trabelsi, W.; Soudani, N.; El Cafsi, M. (2019)
      The effects of frying treatment using diverse gastronomic oils (corn oil, extra virgin olive oil and margarine oil) on the composition of the phospholipids (PLs), nutritional and chemical quality indices were evaluated on the most commercial clams (Venerupis decussata) in Tunisia. The frying treatment resulted in significant changes on saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in almost fried tissues and fried oils (p<0.05). In all cases, frying method caused important enhancement of the main phospholipids compounds as evidence by the increasement of C16:0, C18:0, C16:1, C18:1, n-6PUFA, arachidonic (ARA) and linoleic (C18:2n-6) acids, while reductions of n-3 PUFA, docosahexaenoic (DHA) and ecosapentaenoic (EPA) acids were observed mostly in the fried tissues with margarine followed by corn oil. Our results revealed depletions of the nutritional quality indices (n-3/n-6 PUFA, EPA+DHA and DHA/C16:0) in all fried clams (p<0.01). Besides, the chemical quality indices were assessed through thiobarbituric acid (TBAR), peroxide value (PV) and free fatty acids (FFA), resulting in a significant elevation of these indices in all fried clams. Taken all the data together, frying tests with margarine oil induced a significant enhancement of phospholipids composition. However, frying with olive oil seems to be safer for the nutrition and health of humans.
    • Examination of the nutritional value of four bivalves species from Bizerte lagoon

      Bejaoui, Safa; Rabeh, I.; Chetoui, I.; Telahigue, Khaoula; Ghribi, F.; Fouzai, Ch. (2019)
      Bivalves are known as a healthy nutrition choice due to the highest amounts of nutrients comprising fatty acids mainly polyunsaturated fatty acids (PUFAs). The study is conducted to provide information about the nutritional qualities of four bivalves species (Mytilus galloprovincialis, Cerastoderma edulis, Venus verrucosa and Lithophaga lithophaga) of great commercial value collected from Bizerte lagoon during spring season. The edibility percent, condition index, protein, lipid, moisture, glycogen, fatty acids and nutritional values indices have been also determined. According to our results, high edibility percent and condition index were observed in all investigated bivalves. The results showed that all bivalves could be considered dietary food due to their important contents of proteins, lipid, essential polyunsaturated fatty acids (PUFA), and nutritional quality. The significant contents of the biochemical and fatty acid compositions observed in the present study make L. lithophaga and M. galloprovincialis more appropriate for consumers’ health. This work will be useful for consumers and an impressive marketing tool for shellfishing farmers.
    • The physiological state of the Fucus vesiculosus L. of the Barents Sea in a prolonged air condition

      Ryzhik, I. V.; Makarov, M. V. (2018)
      The increase in anthropogenic pressure on ecosystems necessitated the implementation of measures aimed at purifying the environment and restoring disturbed biocoenoses. To remediate the marine environment from heavy metals, radionuclides, oil products, it has been proposed to use plantations-biofilters, the biological components of which are seaweeds. Fucoids, in particular Fucus vesiculosus, have been identified as the most suitable objects as they have a high sorption activity to heavy metals, radionuclides, are able to include petroleum hydrocarbons in own metabolism. By the standard methods of plant physiological research (determination of photosynthetic activity, content of photosynthetic pigments, relative water content) the ability of F. vesiculosus to withstand prolonged exposure to air has been determined. In the experiment, the algae were placed on the netting, twisted into a roll wrapped with a tarp (to prevent drying plants) and set in different experimental conditions (in constant (8 ?C) and variable (7–19 ?C) temperatures). Algae retained the photosynthetic capacity for 30 days, but after 20 days there was a decrease in this process compared to control. After the experiment, algae recovered the level of photosynthetic capacity for one day. The total content of chlorophylls and the ratio of Chl A / Chl C during the experiment did not change, which also indicates the sustainability of the photosynthetic apparatus of F. vesiculosus. It has been shown that F. vesiculosus is able to maintain physiological activity within 30 days if it is under conditions that ensure moisture retention in the thalli is not less than 55 %. This ability expands the potential of using F. vesiculosus as an object of sanitary aquaculture: it is possible to pre-build modules of plantation-biofilter and their long transportation.
    • History and status of sturgeon stock (Acipenseridae) in the Caspian pool

      Vlasenko, A. D.; Bulgakova, T.I.; Lepilina, I. N.; Konopleva, I. V.; Safaraliev, I. A. (2020)
      Analysis of materials from long-term studies characterizing the current state of sturgeon stocks in the Volga-Caspian fisheries basin, and the dynamics of commercial catches of beluga, sturgeon and stellate sturgeon in the XX – XXI centuries indicates that the Northern Caspian occupies the leading value in catch volumes, where more than 70 % of sturgeon fish are annually harvested. In the first half of the twentieth century sturgeon stocks were determined by the scale of natural reproduction in rivers and fishing volumes; in the second half, natural and anthropogenic factors began to intensively influence the formation of sturgeon stocks. The development of hydraulic construction on rivers, an increase in the withdrawal of freshwater runoff, a decrease in sea level to –29.0 mBS, pollution by industrial and agricultural runoff have necessitated the development of a set of measures for the reproduction, conservation and rational use of the Caspian’s aquatic biological resources. As a result of the studies, the response of the sturgeons to the changed conditions of reproduction has been determined in order to restore and increase their commercial stocks; high ecological adaptability of sturgeons to various living conditions within their range, their exceptional plasticity and pronounced intraspecific differentiation have been established. These indicators point to the possibility of creating conditions that meet the requirements for water quality for the life of sturgeons during migration and reproduction. In the course of the analysis of the obtained data, the influence of regulation of the Volga River flow on the efficiency of natural reproduction of sturgeons has been evaluated; the role of industrial sturgeon breeding in sturgeon stock formation has been shown; the abundance of juveniles in the North Caspian and adult individuals on feeding pastures of the sea has been estimated; trends in the number of sturgeon producers migrating in the Volga to spawning sites have been identified; the prospects for the restoration and rational use of sturgeons in the Volga-Caspian basin have been determined.
    • Some information on biology of three-spined stickleback Gasterosteus aculeatus Linnaeus, 1758 in the Barents Sea coastal region (East Murman)

      Garmash, M. V.; Zhuravleva, N. G. (2020)
      Three-spined stickleback is one of the widespread fish species of East Murman. It is found in 13 catchment areas of the Barents Sea coast in the eastern part of the Murmansk region, including major rivers, shallow river basins and inter-basin spaces. Stickleback is found in such lakes as Enozero, Pervoe Titovskoe, Opasovskoe, Dolgoe, etc, and in the rivers Yokanga, Varzina, Kharlovka, Voronia, Teriberka, etc. There is no detailed biological description of stickleback in this area, and the information available only mentions its presence in water bodies and occurrence in the stomachs of predators. The present paper provides data on three-spined stickleback caught in the coastal region of the Barents Sea at a depth of 120–123 m. The marine form of stickleback spends entire life cycle in the sea. In the Barents Sea, stickleback has a pelagic way of life, going quite far from the shore. According to the published data, its habitat depth in the Barents Sea is 50–450 m, with an average of 270 m, where temperature varies from 0 to 4 °C, with salinity 33–35 ‰. It has been found out that stickleback is represented by two morphotypes – trachurus with a keel (98 %) and semiarmatus (2 %) with a keel. The study has revealed different number of lateral plates and the nature of their distribution on the body of stickleback. In the study area, individuals of different size groups could be found. On average their body length ranges from 51 to 60 mm with a maximum length of 81 mm; the weight changes from 0.79 to 1.39 g. The authors have observed positive allometry of the dependence of mass on body length. Proportion of empty stomachs is almost 100 % with the fat content 1–2 points. The gonads of males and females caught in August 2015 were in after spawning condition. Females comprise the majority of the population (65 %). Infestation of stickleback with helminths is insignificant. Larvae of Anisakis simplex nematode have been observed most frequently during the examination of internal organs and body cavity.
    • Comparative lithological characteristics of modern sediments of the Kara and Pechora Seas

      Chikirev, I. V.; Uliantsev, A.S.; Nikiforov, S.L.; Sorokhtin, N. O.; Dmitrevskiy, N. N.; Libina, N. V.; Kovalev, G. A. (2020)
      Global climate warming and increased anthropogenic pressure on the Arctic shelf contribute to the development of thermoabrasive processes along the coast of the western sector of the Russian Arctic.Comprehensive geophysical, hydroacoustic, geological-geomorphological, and hydrophysical scientific studies were carried out within the Kara and Pechora Seas in June – July 2019, during the 41st cruise of the R/V Akademik Nikolai Strakhov.To test modern sediments, bottom grabbers and shock tube were used. The sampling points were selected based on the materials of continuous seismic profiling and bathymetric bottom survey.As a result of the studies, mapping of the relief and modern sediments within the Kara and Pechora Seas has been carried out and it has been found that the Pechora basin is characterized by various types of sediments and deposits (pelitic mud, aleurite-pelitic mud, clay, silt, sand, moraine deposits), and the Kara Sea is mainly inhabited by thin sediments (pelitic mud). A small amount of sand and siltstone among the bottom sediments of the Kara basin should be associated with an insignificant introduction of terrigenousclastic material from the continent and its deep water. The wide distribution in the southern and central parts of the Pechora Sea of psammiticfacies is due to its shallow water, intensive supply of a large amount of sand-silty material by river flow, processes of solifluction and thermal abrasion of the coasts. In 2020, the next flight of the R/V Akademik Nikolai Strakhov is planned to continue the study of the upper sedimentary stratum and topography of the seabed of the western sector of the Russian Arctic. The purpose of the study is to substantiate the most likely scenario for the development of changes in the natural environment on the shelf, associated primarily with a reduction in the area of ice cover.
    • Background concentrations of heavy metals and other chemical elements in the sediments of small lakes in the south of Karelia, Russia

      Slukovskii, Z. I. (2020)
      The average background concentrations of 42 elements, including heavy metals which are the most dangerous pollutants of the environment, were calculated based on detailed research of sediments of 15 small lakes in the south of the Republic of Karelia. The sediment samples from the lakes were collected from 2016 to 2018. The main items of equipment were a gravity sampler Limnos and hand sampler. The former is capable of producing a 60 cm core and dividing it into 1 cm layers, the latter can enter sediment to a depth of 15 m. All samples were prepared by chemical analysis and measured using uniform methods. The concentrations of chemical elements were taken by the mass-spectral method on a ХSeries-2 ICP-MS. To reveal the layers accumulated in the pre-industrial period, similar research of the area of the Murmansk region and countries of the Scandinavian Peninsula were used. Besides this, the geochemistry and geochronology of lake studies of the author were also used. Eventually, from 73 to 76 samples were taken for an assessment of background concentrations of heavy metals and other elements in the sediments of the lakes from Karelia's south. Given that the data obtained do not obey the normal distribution law, which is often found in geochemistry, the median sample was taken as the averaged background concentration of chemical elements. The results were similar to analog data for neighboring regions, including the Murmansk region and Scandinavian countries. Moreover, the levels of accumulation of chemical elements in lake sediments of Karelia's south are similar to some of the data for stream sediments of the studied region. The exceptions were elements controlled by terrigenous fractions of the stream sediments. This fraction is more rapidly accumulated in the stream and river sediments than in lake sediments. New data can be used for future environmental and geochemistry studies of the sediments of small lakes subject to anthropogenic impact.
    • Assessment of the efficiency of passive thermal protection system of rock massif

      Gusak, S. A.; Orlov, A. O.; Smirnov, Y. G.; Biryukov, V. V.; Palivoda, A. A. (2020)
      The problem of ensuring the stability of rock mass is of particular importance in the conditions of thermal interaction of mine workings with permafrost rocks. The paper presents the results of studying the effectiveness of passive thermal protection system of permafrost massif. Based on a numerical modeling by use of ANSYS FLUENT software complex, studies of thermal interaction of a large-span chamber working and permafrost massif have been performed. On the example of a hypothetical three-dimensional model of mine working with different variations in the material composition of the protective structure (lining) of working and the use of convective heat transfer in the technological channel (air gap), it has been performed the calculated study of the features of the temperature regime of the lining structural elements. There has been carried the estimation of the predicted depth of thawing of rock depending on the design and material composition of the lining and the duration of the thermal impact on the rock massif. The influence of the thermal resistance of the mine working protective structure on the depth and dynamics of thawing rock massif has been studied, the structure determines the conditions of preservation of its cryogenic state and requirements for mining systems of regulation of the thermal regime. The temperature gradients formed in the structural elements of the lining, which can contribute to the occurrence of thermal stresses that have a negative impact on the stress-strain state of the protective structure of the mine working have been founded. On the example of the accepted model representations of the technological channel (temperature of the entering air, width of the channel) the weak influence of heat exchange due to free convection on the intensity of thermal interaction of the working and rock massif has been shown. To reduce the thermal impact on the protective structure of the mine working and the permafrost massif it is necessary to increase the intensity of heat exchange in the technological channel by decreasing the temperature of the air entering the channel, or using the forced convection based on the organization of a special ventilation system.
    • Environmental protection and sustainable development of the mining industry in Murmansk Region, Russia

      Makarov, D. V.; Borovichev, E. A.; Klyuchnikova, E. M.; Masloboev, V. A. (2020)
      The mining complex of the Murmansk region (Russia) has a negative impact on natural ecosystems and worsens the quality of the environment, since the development of non-renewable mineral resources is associated with a significant transformation and destruction of natural communities. In the Murmansk region, where the mining industry forms the basis of the regional economy, the research aimed at achieving sustainable development goals involves the search for 1) new integrated approaches to ensure the development and implementation of environmentally friendly technologies for the extraction and processing of minerals; 2) managerial decisions supporting the transition to a circular economy; 3) the establishment and development of protected areas, including compensatory; 4) the restoration of disturbed landscapes; 5) the development of nature-like technologies for the recovery of valuable components from minerals, and 6) the protection of the environment. Futhermore, there is need for a constant search for some balance of interests of local communities and mining corporations in the context of environmental protection and economic development in order to maintain social sustainability. Without designing the foundations of the state policy for the transition to a closed-loop economy, the implementation of even existing technologies will be too slow. There is a survey of nature-like technologies developed in the Kola Science Center of the Russian Academy of Sciences for processing minerals and protecting the environment, rehabilitation of disturbed areas exposed to industrial air pollution, reclamation of the water and land areas polluted by oil and oil products as well as examples of territorial nature conservation that do not block the development of processing minerals.
    • Fadeev Stream and spring of the same name: Water quality and geo-ecological characteristics

      Glazova, V. A.; Gaponenkov, I. A.; Fiodorova, O. A.; Dauvalter, V. A. (2020)
      Research of the geoecological and hydrochemical characteristics of the water of the Fadeev Stream (surface source) and the spring "Fadeev Stream" (underground source) located in the Kola District of the Murmansk Region has been carried out in order to identify the influence of the anthropogenic factor on the formation of its hydrochemical composition, caused primarily by the consequences of construction and reconstruction of Eastern bypass highway located around the city of Murmansk. The sampling has been taken accounting the requirements of regulatory documents to perform measurements; the tests have been carried out according to standard methods of hydrochemical analysis. In the course of the study, it has been found that the waters of the Fadeev Stream and the underground source are of natural origin; there is no influence of technogenic factors. The Fadeev Stream water is very soft, slightly mineralized, with significant variations in color depending on the season, there is swamp nutrition of water bodies. The spring water can be described as slightly acidic, very soft, ultra-unleavened with a variable chemical composition depending on the season of the year. The increase in the content of pollutants in the spring water is observed during periods with the most intense precipitation and heavy snowmelt. Precipitation can wash out pollutants from the soil or parent rock. A comparison of the qualitative composition of water from surface and underground water sources has shown that at the sampling points, natural waters have a natural genesis and are not affected by anthropogenic factors.
    • The traditional fishery «charfia» in Chebba (Middle Eastern Tunisia): technical characteristics, catch composition and the related social issues

      Moussa, Hamdi; Shili, A.; Nasraoui, S. (2019)
      The « Charfia » is a traditional, sustainable fishing method that catches fish alive. The study emphasizes the first assessment of this technique in Chebba area. It provides a catch analysis, and aims to characterize its technical aspect as well as mapping its implementations. In Chebba area 15 implantations of Charfia traps were identified and located. Traps are mainly made out of multifilament gillnets interspersed with palm leaves. These fisheries are of complex type, formed out of multiple consolidated implantations. Scale based plan of all the Charfia implantations was made. Some factors are influencing the production in Chrafi as the position of the implantation and its maintenance. We noticed a quantitative and qualitative variation from one Charfia to another. Furthermore, fish accession to the Chrafi’s fish traps is governed by the sea currents, tides, anticyclonic winds and other hydrodynamic factors. Charfia have been affected by the changes in the traditional materials constituting it, which might impact negatively the environment and the fisheries resources.
    • The ages and rock mineral composition of the Pechenga eastern frame, the Kola Region

      Nitkina, E. A.; Kaulina, T. V.; Kozlov, N. E. (2020)
      The research and dating of rocks in the area of the Central Kola block (the Kola Peninsula) is due to the need to develop the Lyceum uranium ore area, the most promising for uranium mining in the Kola region, located in close proximity to the study area and composed of similar gneisses from the Kola series. Within the Central Kola block, Archean complexes are represented by granite-gneisses and migmatites with relicts of biotite-plagioclase, biotite-amphibole-plagioclase gneisses, amphibolites, garnet-biotite-plagioclase and aluminous gneisses containing interlayers of ferruginous quartzite (quartz metasomatites) of various capacities. The rocks are repeatedly metamorphosed in conditions from high-temperature steps of the amphibolite facies to the granulite facies. Geological and geochronological methods have established the sequence of geological processes manifested in the rocks of the Kola series of the northwest framing of the Pechenga structure. The results of U-Pb dating are determined by zircon grains of the following genesis: metamorphic – in gneiss; magmatic and metamorphic – in metagabbro; metamorphic and metasomatic – in quartz metasomatite. The data obtained have made it possible to establish the age sequence of geological processes: 2.8 Ga – the time of metamorphism of garnet-biotite gneisses; 2,722 ? 9 Ma – crystallization of granodiorites; 2,636 ± 41 Ma – the formation of aplitic granites; 2,620 ? 16 Ma – the emplacement of pegmatites; the age of aplitic granites and pegmatites marks the final stages of the Archean evolution of the region; 2,587 ± 5 Ma – the emplacement of gabbroids, 2,522–2,503 Ma – the period of the thermal process associated with the formation of quartz metasomatites during the metamorphism of gabbro and garnet-biotite gneisses; 2,507 ± 7 Ma – metamorphism, schist and budding of gabbroids.
    • New occurence and new records of fish species of Tunisian coasts

      Bradai, Mohamed Nejmeddine; Enajjar, Samira; Saidi, Bechir (2019)
      Investigations conducted in the Gulf of Hammamet (Central Tunisia) between 2013 and 2017, revealed the sighting of six new species of fish not reported in the area. Five species are observed in the landings of the Teboulba artisanal fishery. Among them, two are mentioned for the first time in Tunisia: The goatfish Upeneus moluccensis (Bleeker, 1855), a non-native species of the Mullidae family and the Alexandria pompano Alectis alexandrinus (Geoffroy Saint-Hilaire, 1817) (Carangidae). Two other rare species not observed during the last three decades in Tunisia are noted: The zebra seabream Diplodus cervinus cervinus (Lowe, 1838) (Sparidae) and the Red Seabream Pagellus bogaraveo (Brünnich, 1768) (Sparidae). The squirrelfish Sargocentron rubrum (Forskäl, 1775) (Holocentridae) is an exotic species detected in Tunisian water for the second time during this study. A cartilaginous fish was landed in the port of Mahdia: The Atlantic torpedo, Torpedo nobiliana Bonaparte, 1835, not observed since 80’s
    • Geodynamics and metallogeny of the Keivy domain (Baltic Shield)

      Kozlov, N. Е.; Sorokhtin, N. О.; Martynov, E. V.; Marchuk, T. S. (2020)
      Geodynamic and petrogeochemical study of the Keivy domain in the Baltic Shield has shown that it was overlapped by surrounding microcontinents in the Archean. As a result, the Baltic Shield was subject to cratonization. Thus, the Keivy microcontinent can be considered as the most ancient known median massif of the continental crust. Specific features of its geodynamic evolution predetermined conditions for formation of unique in scale stratiform deposits of alumina raw materials on the surface of the microcontinent. The paper describes and justifies the mechanism of alumina formation by physical-chemical decomposition of Archean and early Proterozoic metamorphosed sedimentary complexes in the Kola region of the Baltic Shield. Besides, the study of metallogenic features of transformation processes in the Archean continental crust of the Keivy microcontinent and its rimming suggests that carbonaceous schists of the Keivy domain that formed in the sedimentary cover can be significantly rich in nanogold. It will allow considering the central part of the Kola region as a major gold-bearing province. The authors believe that the metallogenic forecast based on geodynamic reconstructions is promising for further research of early Precambrian complexes. This work continues a series of publications on structural-material study of the Keivy domain.
    • Structures of sulfide melt crystallization as an indication of metamorphism of the ores in the Oleninskoe gold deposit

      Kalinin, A. A.; Savchenko, Ye. E. (2020)
      Multiphase fine aggregates of galena, pyrrhotite, freibergite, pyrargyrite, diaphorite, fizelyite, uchucchacuaite, ullmanite, and some other minerals are found in the ores of the Oleninskoe gold deposit in the Kolmozero-Voronya greenstone belt (Kola Peninsula, Russia). The aggregates are considered to be the product of crystallization of sulfide melt formed of the minerals of low-melting-point chalcophile elements (Zn, Ag, Cd, Tl, Pb, As, Sb, Bi, Se, Te, etc.) during heating to the temperature above 500 °C. This origin of the aggregates is affirmed by: 1) multiphase composition (up to 6 minerals) of the aggregates; 2) absence of signs of replacing early minerals by the late ones; 3) essential presence in the aggregates of the minerals of chalcophile elements Ag, Pb, Sb, i. e. elements with a low melting point of their compounds; 4) roundish droplet form of inclusions of minor minerals in the main sulfide, and 5) aggregates' position at the boundary sulfide – quartz or in fractures in vein minerals. Partial melting and crystallization of sulfide melts took place during Paleoproterozoic metamorphic event, when the Neoarchean sulfide-bearing rocks were mid-amphibolite metamorphosed under the temperature > 500 °C. Signs of the Paleoproterozoic metamorphism are found in the ores of the neighboring Cu-Mo porphyry Pellapahk deposit as well.
    • Seismic effect of industrial explosions of GOK Kostomuksha

      Zueva, I. A.; Lebedev, A. A. (2020)
      Active development of quarries in the Republic of Karelia contributes to the improvement of the control system of the parameters of drilling and blasting operations with the aim of ensuring the safety of buildings and structures near mining facilities. During the study of the seismic effect of industrial explosions, the technology of blasting has been considered and a typical scheme of blasting at a mining enterprise has been described. In the quarries of the Kostomuksha mining and processing plant, to reduce the seismic effect, short-blasting is used. The created monitoring system in Karelia makes it possible to select not only teleseismic earthquakes, but also regional and local scale events on the seismic records. Explosions are recorded by seismic stations of the Karelian network and other regions if the magnitude of the event is more than 1.7. As a result of the waveforms' analysis of the records of the seismic station KOS6, located a few kilometers from the quarries, a clear entry of the transverse wave has been noted. The values of the local magnitudes of the explosions established during the six months of 2018 vary from 1.5 to 2.5 and do not exceed 3. The constructed averaging line shows the dependence of magnitude on the total charge; facts of its growth are noted with an increase in the total mass of the charge, as well as significant spread of data from the averaging line. In the course of the study, the possibility of reducing the seismic effects of industrial explosions through the use of effective short-delayed invocation schemes has been determined.
    • Residual magnetization of various genetic rocks and ores of the Kola Region under the influence of mechanical oscillations

      Zhirova, A. M. (2020)
      The paper considers magnetoelastic phenomena in rock samples. Research is of interest for solving problems of nonlinear geophysics, as well as of some issues of materials science. Magnetite-bearing rocks and ores have been sampled in different geological structures of the Kola region in order to study their magnetoelastic properties. All samples have been subject to elastic mechanical oscillations in laboratory conditions. The experiment has been conducted under changing impact parameters of acoustic waves. The effect of signal amplitude on magnetic properties of the samples has been first studied using magnetite-bearing amphibolites from the Serpovidny Ridge structure. According to results of the experiment, it is considered reasonable to use a pulse signal with higher amplitude in the future. An effect of a signal direction regarding a vector of residual magnetization has been studied, using rocks with different ferromagnetic contents. Values of natural residual magnetization of the studied samples vary from 100 А/m to 0.5 А/m. The study has indicated some relation between a spatial behavior of a vector and a direction of the acoustic impact in rocks with high magnetite content. In particular, the spatial location of the vector changes considerably, when the angle between the direction of the acoustic wave front and the magnetization vector of samples is 100 degrees and more. No statistically significant relations or patterns have been identified for low-magnetic samples. At the final stage, the effect of duration of elastic mechanical oscillations impact on magnetic properties of rocks has been studied. Results of the research also indicate an interrelation between an impact of this acoustic effect and an amount of the magnetic matter in the rock. Thus, a significant response of the samples' magnetic state is registered during the acoustic impact on rocks with high ferromagnetic content. In general, it has been concluded that studying electromagnetic effects on high-magnetic samples is more promising compared to rock samples with lower ferromagnetic content.
    • Study of the structure and seismicity of the near-surface zone of the earth's crust at the White Sea seismogenic zone on the Kola Peninsula

      Demakhin, A.Yu. (2020)
      The Kandalaksha-Bothnian deep fault is the subject of a comprehensive geological and geophysical study in connection with the development of the Shtokman gas field on the Kola Peninsula. In the process of studying the structure and seismicity of the near-surface zone of the earth's crust in the vicinity of the route of the planned Shtokman – Volkhov gas pipeline, the following have been carried out: 1) lineament analysis of the topographic map where the lines of the supposed faults were plotted, corresponding to the beds of the largest rivers, large streams, elongated lakes and bays; 2) analysis of the geological profile along the class I levelling line; 3) comparison of the lineament analysis results with the results of the geological profile analysis along the levelling line. When determining seismic risks, the sources of earthquakes occurred in the study area have been mapped; the impact of recorded earthquakes on the designed pipeline has been estimated and seismic intensity has been calculated at the point of the pipeline route design closest to the earthquake epicenter. Georadar studies of areas of the Kandalaksha seismogenic zone, interpretation and analysis of the obtained radarograms have made it possible to identify lineaments that coincide in location with faults, subsurface boundaries indicated on the geological section, outline the layers of bulk and natural soils and rocks with high accuracy and identify areas with anomalous physical and mechanical properties, fracture zones, as well as the boundary of the rocky base under the moraine and to conclude that the earthquakes occurred theoretically would not have had a significant impact on the projected pipeline. Thus, it is possible to carry out industrial construction in the study area (including linearly extended objects), taking into account the limitations caused by the Kandalaksha-Botnichsky deep fault seismicity indices obtained during georadar analysis.
    • Value Chain Analysis of Maliputo, Caranx ignobilis in the Philippines

      Mutia, Maria Theresa M.; Muyot, Myla C.; Balunan, Rielyn L.; Muyot, Frederick B. (2020)
      Maliputo (Caranx ignobilis) is a high-value food fish in the Philippines with limited studies on market potential. This value chain analysis study was conducted to understand the industry, to identify the key actors, supply and value chain, and to identify issues and concerns to support the development of C. ignobilis industry. A survey interview was conducted using purposive sampling in nine maliputo-producing regions with 224 respondents, and focus group discussion validated the analyzed data. Key chain actors identified are fishers, fish cage operators, fish buyers categorized as small-scale (local vendors and peddlers) and large-scale intermediaries (commission agents and wholesalers), and processors (restaurants and resorts). Annual production was 188,722 kg valued at PHP 33,752,859.79 with 58.12% coming from capture fisheries and 41.88% from aquaculture. Major producing regions for captured and cultured C. ignobilis are Regions 2 (Cagayan), 6 (Iloilo), and 3 (Central Luzon). The industry’s value chain map showed a gross value addition of PHP 116.58, 135.65, 75.04, 23.58, and 749.71 per kg maliputo for capture, aquaculture, small-scale fish buyer, large-scale fish buyer, and processors, respectively. Processors attained the highest net returns while fishers got the lowest. This study noted that C. ignobilis is a non-target species in capture fisheries resulting in an inconsistent supply of the fish. For aquaculture, there is a need to improve its culture technology, develop seed production technology, and formulate an artificial diet. Various upgrading strategies to improve the industry and to increase the benefits derived by the key actors had been identified and presented in the paper.
    • Reproductive Biological Performance of Otolithes ruber (Bloch and Schneider 1801) in San Miguel Bay, Philippines

      Lanzuela, Noemi SB.; Gallego, Errol M.; Baltar, Jethro Emmanuel P. (2020)
      The tigertooth croaker, Otolithes ruber (Bloch and Schneider 1801), was studied to determine its reproductive biology characteristics for 34 months from March 2015 to November 2017. A total of 7,977 individuals were sampled and the measured total lengths (TL) ranged from 8.1 cm to 32.1 cm (16.70 ± 2.53 cm ) and 10.0 cm to 33.5 cm (17.95 ± 2.95 cm) for male and female, respectively. The length-weight relationship can be summarized as W = 0.00521 L3.18 and W = 0.00837 L3.01 for female and male, respectively. The length at first maturity of this species was determined to be 13.95 cm, which is smaller compared to other studies. The overall sex ratio of this species was 1:0.8, with males dominating the female sex (P < 0.05, X2 = 64.3). In addition, synchronized development of male and female gonads was observed. It was also verified that mature individuals were present all throughout the study period indicating that this species spawn continuously and the presence of juveniles during the sampling period indicated continuous recruitment. Mean monthly GSIs indicate July to November as the main spawning season of this species. The in-site occurrence of mature and juvenile stocks in the bay further implicates that San Miguel Bay is a nursery ground for this species. The fecundity varied between 3,420 to 422,100 with an average fecundity of 86,142 eggs. Lastly, the spawning potential ratio is still above the limit reference point (SPR = 0.36), indicating that the stock can still replenish their biomass.