Decrease In Salinity Research Articles

Remote sensing inversion of the Zabuye Salt Lake in Tibet, China using LightGBM algorithm

The Zabuye Salt Lake in Tibet, China is the only salt lake in the world that contains natural crystalline lithium carbonate. The grade and spatial distribution of mineral resources are of great importance to the development and utilization of salt lake mineral resources. The use of remote sensing technology for salt lakes observations can overcome the disadvantages of traditional station observations, such as spatial discontinuity, high time consumption, and high labor costs. In addition, machine learning algorithms can efficiently analyze the information from remote sensing data. In this study, Landsat-8 remote sensing image data and the Light Gradient Boosting Machine (LightGBM) algorithm were used to perform inversions of the depth, salinity, and lithium concentration of the Zabuye Salt Lake. Moreover, the water volume, total salinity, and total lithium content of Zabuye Salt Lake in 2000 and 2017 were estimated, and the distribution of mineral resources and changes during the study period were analyzed. The results show that the water depth and volume of the entire lake increased sharply in 2017, resulting in a decrease in salinity and lithium concentration in the lake. Due to the inflow from the surrounding dry salterns, the South Lake experienced a relatively small change. Furthermore, the amount of lithium resources in North Lake decreased significantly in 2017 compared to 2000, possibly due to higher temperatures during the month of observation, which led to precipitation of lithium carbonate. Our study proves the feasibility and accuracy of the LightGBM machine learning algorithm for rapid inversion of salt lakes, which provides technical insight into remote sensing inversion of other mineral resources in salt lakes. Thus, the development of remote sensing technology in recent years can provide increasingly detailed assessments of salt lake resources in the future.

The relationship between bacterial outer membrane vesicles and halophilic adaptation.

Many cells are known to actively release nano-sized outer membrane vesicles (OMVs) that contain bioactive proteins, lipids, and nucleic acids into the extracellular environment. These vesicles have been associated with adaptation to environmental stress in other species, but their role in halophilic salt stress adaptation is not known. This study aimed to isolate and characterize the OMVs of Halomonas caseinilytica KB2 at various salt concentrations [6% (KB2-6), 12% (KB2-12), and 18% (KB2-18)] and to identify the patterns of adaptations to increasing salinity in its structure, protein composition, and expression. Also, a comparison with the composition of OMVs of E. coli, a mesophilic bacterium, was performed. Bioinformatics and statistical analysis were carried out to elucidate the underlying proteome differences that may exist as a result of increasing salinity. The results show that OMV production in H. caseinilytica KB2 is promoted by a decrease in salinity. OMVs also revealed possible structural and metabolic changes happening in the cells which led to the deduction that cells become more stable with increasing salt concentrations. Cell wall integrity, protein expression and folding are important. Although H. caseinilytica KB2 OMVs show cellular changes with changing salt concentration, they may not play a direct role in adaptation to changing salinity.

Lateral variations in the Hosen 8‐2 vein in the Hishikari deposit, Japan: Implications for high Au‐grade zone

AbstractLateral sampling of each blasting interval (~ 2.6 m) along a 79 m strike length was conducted for the Hosen 8‐2 vein on the −5 ML (mining level, meters relative to sea level) of the Main ore zone in the Hishikari epithermal Au deposit, Kagoshima, Japan. The horizontal variation of mineral textures, bulk chemical compositions, and fluid inclusion temperatures and apparent salinity of ore fluids were determined. The major gangue minerals of the quartz veins studied include quartz and adularia with minor amounts of calcite and smectite. The major ore minerals include electrum, galena, and sphalerite with minor pyrite, petzite, and hessite. Electrum commonly occurs in a discrete band with microcrystalline quartz, granular adularia, and smectite. The electrum‐bearing band is followed by tabular adularia, and finally by granular or comb quartz. Mineral textures that indicate high degrees of supersaturation with respect to amorphous silica (presently quartz with microcrystalline/mosaic and feathery textures) and adularia (with tabular, rhombic, and granular textures) were common throughout the vein strike. Bulk chemical analyses indicate that Au grade is positively correlated with Ag, Bi, Pb, and Te contents. A bonanza zone with Au grades up to 10,800 ppm occurs in the central part of the Hosen 8‐2 vein on the −5 ML, and is associated with high adularia content, calculated as adularia / (quartz + adularia). The wide lateral variation in the geochemical composition contrasts with the consistent association of electrum with microcrystalline quartz, granular adularia, and smectite throughout the Hosen 8‐2 vein on the −5 ML. Fluid inclusion microthermometry of primary and pseudosecondary inclusions in quartz and adularia yielded histogram modes of homogenization temperature between 160 and 240°C; the most frequent mode is 200–210°C, with most data within ±10°C from this value. The maximum ice‐melting temperature of most samples excluding late comb quartz is −1.5°C, which is equivalent to an apparent salinity of 2.6 wt% NaCl eq. The wide variation in ice‐melting temperatures and apparent salinities (up to 5.2 wt% NaCl eq.) may be due to dissolved CO2 in the fluids, while the sharp decrease in apparent salinity with temperature decrease indicates CO2 loss due to fluid boiling during vein formation. The intimate association of electrum with microcrystalline quartz that recrystallized from amorphous silica indicate sharp boiling and vapor loss as the primary mechanism of Au deposition in the Hosen 8‐2 vein.

도암만 사내호 방류에 의한 담수 확산범위 예측에 관한 연구

To estimation of effect by water discharge from Sanae reservoir in Doam bay, we were conducted to field survey and numerical simulation. In field sequence survey, physical effects by water discharge from Sanae reservoir appeared clearly at discharge early, and decreased greatly since 2 tidal period. Flow pattern of flood tide to calculated by hydrodynamic model was appeared to inflow through two channel, Maryang~Gogeumdo and Wando~Gogeumdo. Flow pattern of ebb tide showed reverse pattern to flood tide. The residual current, which were obtained by intergrating the simulated tidal currents over 1 tidal cycle, showed more than 10cm/sec at interval sea of Maryang and Gogeumdo. And the front sea of Sanae reservoir appeared fewer than 5 cm/sec. The range of salinity decrease by numerical simulation appeared extensively when ebb tide than flood tide. When water discharge increased 30% of total reservoir capacity, freshwater Diffusion area was shown to inner area in Doam bay. And when water discharge increased 50%, effect area extended to Maryang sea area.

The Effect of Reduce Salinity on Behavior and Stress Response in Vannamei Shrimp (Litopenaeus vannamei)

One of the parameters that play an important role in the success of vannamei shrimp cultivation is salinity. This study aims to determine the effect of decreasing salinity on the behavior and stress response of vannamei shrimp. The test animals used were vannamei shrimp, which were in logs with an average weight of 4.6 – 6.3g. This study used a completely randomized design (CRD) with different salinity reduction treatments in each maintenance medium, namely Treatment A without decreasing salinity, Treatment B decreasing salinity 2 ppt per 6 hours for 24 hours, Treatment C decreasing salinity 2 ppt per 4 hours for 24 hours, Treatment D decreased salinity 2 ppt per 2 hours for 24 hours, each treatment was repeated 3 times. Blood glucose was measured after the decrease in salinity and on the last day of the study. Blood glucose collection was carried out at the fifth swimming leg on white shrimp using a 1 ml syringe that had been rinsed using Na Citrate with the aim that the blood glucose taken did not clot quickly. The results showed a decrease in salinity caused by shrimp stress. The concentration of vannamei shrimp blood glucose increased (13.66 – 52.37mg/dl). Treatment D was the best glucose concentration to suppress blood glucose concentrations (13.66mg/dl). Based on the data analysis of blood glucose concentration (p<0.05) it continued with the real difference test. Vannamei shrimp behavior during salinity reduction showed a response that was not different from all treatments. Salinity 6 ppt is good salinity in the process of suppressing blood glucose concentrations when changes in water salinity occur.

Desalinization of degraded soils by atmospheric precipitation and Biosolvent for saving water resources

In the Syrdarya region of Uzbekistan, the influence of atmospheric precipitation on changes in the degree of salinity and chemical composition of the upper 30 cm soil layer was studied. Experiment options: 1 - loosening the soil to a depth of 70 cm, 2 - loosening, followed by soil treatment with preparation containing polymaleic acid. A decrease in the degree of soil salinity by 7 - 8 dS/m has been established with the help of only 302 mm of precipitation, without water wasted for leaching. The decrease in soil salinity was: according to EU, 56% - in option 2, and 52% - in option 1. According to TDS, the salinity reduction was: - 61 and 52%, according to SO “4. - 58 and 47%. The content of calcium in the variant with the use of Biosolvent decreased by 48%, and in the control variant, it increased by 15%. It has been estimated that with a decrease in salinity from 16 to 8 dS/m, a possible increase in the yield of a salt-tolerant barley crop by 1.6 t/ha is possible. Taking into account the costs of loosening and tillage with the preparation, the net income of the farmer can be $480/ha.

Tidal restoration to reduce greenhouse gas emissions from freshwater impounded coastal wetlands

Freshwater impounded wetlands are created by artificially restricting coastal wetlands connection to tides. The decrease in salinity and altered hydrology can significantly increase greenhouse gas (GHG) emissions, specifically methane (CH4). Restoration of freshwater impounded wetlands through tidal reintroduction can potentially reduce GHG emissions; however, studies in tropical regions are scare. This study investigates the potential for tidal restoration of impounded freshwater coastal wetlands by comparing their GHG emissions with tidally connected mangrove and saltmarshes in the Burdekin catchment in Queensland, Australia. We found that freshwater impounded wetlands had significantly higher CH4 emissions (3,633 ± 812 μg CH4 m−2 hour−1) than mangroves (27 ± 8 μg CH4 m−2 hour−1) and saltmarsh (13 ± 8 μg CH4 m−2 hour−1). Soil redox, moisture, carbon, nitrogen, and bulk density were all significantly correlated to methane emissions. Conversely, freshwater impounded wetlands had significantly lower nitrous oxide (N2O) emissions (−0.72 ± 0.18 μg N2O m−2 hour−1) than mangroves and saltmarsh (0.35 ± 0.29 and 1.32 ± 0.52 μg N2O m−2 hour−1 respectively). Nevertheless, when converting to CO2 equivalents (CO2‐eq), freshwater impounded wetlands emitted 91 ± 20 g CO2‐eq m−2 hour−1, compared to the much lower 0.8 ± 0.2 and 0.7 ± 0.2 g CO2‐eq m−2 hour−1 emission rates for mangroves and saltmarsh. In conclusion, restoration of freshwater impounded wetlands through tidal restoration is likely to result in reduced GHG emissions.

Histopatology kidney of seed white snipper (lates calcarifer bloch) which experienced a different decrease in salinity

White snapper (Lates calcarifer Bloch) is a consumption fish that has high economic and nutritional value. FAO stated that white snapper was a diversified species in aquaculture in 2018. This is because white snapper has many advantages such as fast growth rate, high fecundity, easy hatchery techniques in controlled containers, and high adaptability to various environmental conditions. The method used in this study was experimental with a completely randomized design (CRD) technique using 3 treatments with each treatment being repeated 3 times. The 3 treatments include; A : Water medium with a salinity content of 5 ppt; B : Water medium with a salinity content of 10 ppt; C : Water media with 15 ppt salinity. In this study, white snapper seeds measuring ±3 cm were given 3 different salinity treatments. The three treatments, salinity 5 ppt, 10 ppt, and 15 ppt caused histopathological abnormalities in the kidneys of snapper fish which were used as research objects. The kidney organ has Melano Macrophages Centers (MMC) and Necrosis (N). Kidneys with MMC are characterized by the presence of inflamed organ parts and a collection of pigmented macrophages. The occurrence of necrosis is characterized by the loss of tissue structure and then the kidney tissue is damaged, as well as the loss of cell boundaries or cell nuclei.

Experimental Study and Numerical Simulation of W/O Emulsion in Developing Heavy Oil Reservoirs

In the process of waterflooding development of heavy oil, W/O emulsion has a strong ability to improve the mobility ratio and block the high-permeability layer, which can effectively improve the sweep coefficient and enhance oil recovery. In this paper, the stability and droplet size distribution of emulsions under different conditions were studied by taking heavy oil and formation water from Jimusar Oilfield in Xinjiang as samples. On this basis, double-pipe core flooding experiments were carried out to study the shut-off ability and oil displacement efficiency of W/O emulsion, and then a numerical simulation was carried out. The results show that oil and water can be completely emulsified when the stirring speed is higher than 4000 r/min. A stable emulsion can be formed when the experimental temperature is lower than 60 °C. A lower water cut results in a more stable emulsion. The emulsion is difficult to stabilize after the salinity exceeds 10,000 mg/L. When the pH value is about 7, the stability of the emulsion is the worst. With the increase in stirring speed, the increase in temperature, and the decrease in water content and salinity, the emulsion droplet size range is relatively concentrated, and the average particle size is smaller. In heterogeneous reservoirs, the permeability of different percolation channels is quite different, such that the displacement fluid only percolates along the high-permeability channel and cannot drive oil effectively. The results of displacement experiments show that the emulsion with a water cut of 60% has high viscosity and obvious sweep ability, but its stability is very poor; the effect is opposite when the water cut is less than 40%. The shut-off ability of W/O emulsion disappears gradually when the permeability contrast is more than 5.92. The research results are of great significance for improving oil recovery in heterogeneous heavy oil reservoirs.

Sustainability of Coastal Agriculture in the Face of Soil Degradation: The Influence of Water Salinization as an Example

The pump-irrigated soils of the coastal Chaouia in Morocco are subject to changes in their qualities due to the quality of the irrigation water and their proximity to the sea. This work aims to approach irrigation water quality and the influence of these waters on the quality of agricultural soils. The study is based on the systematic and selective sampling of water and soils (19 water samples and 19 soil samples). Analyzed parameters mainly include the salinity and pH of the soil and water samples. The main results show that soil pH varies from 6.81 to 7.7. However, the pH of the water varies from 6.22 to 8.13. The electrical conductivity in soils varies from 12,260 μs/cm to 700 μs/cm and from 1123 μs/cm to 8120 μs/cm. The results of the analysis of soil salinity show that in moving away from the sea, the salinity decreases, and the salinity of the water samples follows the same trend. The Richard and Wilcox graphs show that most water samples taken near the sea are highly mineralized and have poor water quality. This paper presents important aspects of the feasibility of coastal agriculture and can be a source of inspiration for future research and planning of coastal agriculture.

Genetic Mechanism for Antioxidant Activity of Endogenous Enzymes under Salinity and Temperature Stress in Turbot (Scophthalmus maximus).

Three antioxidant properties (corresponding to the enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase) were measured in the livers of Scophthalmus maximus under different salinities/temperatures (5, 10, 20, 30, and 40‰/17, 20, 23, 25, and 28 °C). Split-plot (SP) analysis, additive main effects, and multiplicative interaction (AMMI) and genotype × environment interaction (GGE) biplots were used to analyze genotype × salinity/temperature interactions for antioxidant properties. The results of the SP analysis show that the activity of the three antioxidant properties was significantly (p < 0.01) affected by salinity/temperature, antioxidant, and salinity/temperature × antioxidant interaction. The results of the AMMI analysis for salinity reveal that the effect of genotype, salinity, and genotype × salinity interaction on antioxidant properties reached a significant level (p < 0.001); 92.1065%, 2.6256%, and 4.4360% of the total sum of squares for antioxidant property activity were attributable to the effects of genotype, salinity, and genotype × salinity interaction, respectively. The results of GGE biplot analysis for salinity reveal differences in the activity ranking of the three antioxidant properties under five salinities; this difference expands with an decrease or increase in salinity from 30‰ (optimum salinity). A salinity of 5‰ had the strongest ability to identify the three antioxidant properties. The five experimental salinities were divided into one region, and SOD activity was the highest in this region. In a comprehensive analysis of stability and activity, SOD had the best activity and stability. The results of AMMI analysis for temperature reveal that genotype, temperature, and genotype × temperature interaction had significant effects on the antioxidant properties (p < 0.001); 82.4720%, 4.0666%, and 12.0968% of the total sum of squares for antioxidant property activity were attributable to the effects of genotype, temperature, and genotype × temperature interaction, respectively. The results of GGE biplot analysis for temperature reveal a large difference in the activity ranking of antioxidant properties between 17 °C and the other four temperatures, while only small differences in the activity rankings were detected among the other four temperatures. The difference in the activity ranking of antioxidant properties was greatest between the temperatures of 17 and 20 °C. A temperature of 17 °C showed the strongest ability to distinguish the three antioxidant properties. Additionally, the five test temperatures were grouped into one region, and comprehensive analysis of activity and stability showed that SOD had the best activity and stability.

Effect of tides on river water behavior over the eastern shelf seas of China

Abstract. Rivers carry large amounts of freshwater and terrestrial material into shelf seas, which is an important part of the global water and biogeochemical cycles. The earth system model or climate model is an important instrument for simulating and projecting the global water cycle and climate change, in which tides however are commonly removed. For a better understanding of the potential effect of the absence of tides in the simulation of the water cycle, this study compared the results of a regional model with and without considering tides, and evaluated the effect of tides on the behavior of three major rivers (i.e., the Yellow, Yalujiang, and Changjiang rivers) water in the eastern shelf seas of China from the perspectives of transport pathways, timescales, and water concentration. The results showed that the tides induced more dispersed transport for the water of the Yellow and Yalujiang rivers, but more concentrated transport for the Changjiang River water. The effect of tides on the transit areas of the Yellow, Yalujiang, and Changjiang rivers was 13 %, 40 %, and 21 %, respectively. The annual mean water age and transit time of the three rivers in the model with tides were several (∼ 2–10) times higher than those in the no-tide model, suggesting that tides dramatically slow the river water transport and export rate over the shelf. By slowing the river water export, tides induced a three-fold increase in river water concentration and a decrease in shelf seawater salinity by &gt; 1. Moreover, the effect of tides on river behavior was stronger in relatively enclosed seas (i.e., the Bohai and Yellow seas) than in relatively open seas (i.e., the East China Sea). The change in the shelf currents induced by tides is the main cause of the difference in the river water behavior between the two model runs. Tides can increase bottom stress and thus weaken shelf currents and decrease the water transport timescales. The improvement in tidal parameterization in the no-tide model in the simulation of river water behavior was very limited. Given the important role of river runoff on the global water cycle and the effect of changes in river water behavior on ocean carbon cycling, it is important to include the tidal effect in earth system models to improve their projection accuracy.

Water Desalination Using Polyelectrolyte Hydrogel: Gibbs Ensemble Modeling.

Polyelectrolyte hydrogels can absorb a large amount of water across an osmotic membrane as a result of their swelling pressure. On the other hand, the insoluble cross-linked hydrogel network enables dewatering under the influence of external (thermal and/or mechanical) stimuli. Moreover, from a thermodynamic perspective, a polyelectrolyte hydrogel is already an osmotic membrane. These properties designate hydrogels as excellent candidates for use in desalination, at the same time avoiding the use of expensive membranes. In this article, we present our recent theoretical study of polyelectrolyte hydrogel usage for water desalination. Employing a coarse-grained model and the Gibbs ensemble, we modeled the thermodynamic equilibrium between the coexisting gel phase and the supernate aqueous salt solution phase. We performed a sequence of step-by-step hydrogel swellings and compressions in open and closed systems, i.e., in equilibrium with a large and with a comparably small reservoir of aqueous solution. The swelling in an open system removes ions from the large reservoir, whereas the compression in a closed system decreases the salt concentration in the small reservoir. We modeled this stepwise process of continuous decrease of water salinity from seawater up to freshwater concentrations and estimated the energy cost of the process to be comparable to that of reverse osmosis.

Transcriptome and metabolome analyses provide insights into the salinity adaptation of clam Ruditapes philippinarum

Salinity is an important environmental factor affecting the growth and survival of marine organisms. Marine shellfish possess the efficient osmoregulatory mechanism to cope with either hypo- or hyperosmotic stress. However, little is known about the molecular and metabolic adaptation involved in the osmotic regulation of these intertidal habitants. The Manila clam Ruditapes philippinarum is a worldwide cultured intertidal shellfish, which usually encounters a great risk of salinity stress in its coastal habitats. In the present study, the integrated analysis of transcriptomics and metabolomics was performed to investigate the transcriptional and metabolic profiles of the clams in response to abrupt salinity decrease. The comparative transcriptome analysis uncovers the changes of genes involved in ion channel activation, amino acid metabolism, and energy metabolism in the salinity-stressed condition. The metabolomics analysis reveals that the glucose-succinate pathway may play a critical role in energy metabolism during the osmotic stress. The multi-omics analysis reveals that neural adaptation to salinity stress may be potentially regulated by arachidonic acid metabolism and glutathione metabolism. The important metabolites (12-HPETE, PGEs, and spermine) may be served as the signaling molecules in response to acute salinity stress in the intertidal shellfish. These findings suggest that clams may get through the osmotic stress by ion channel activation, neural adaptation, and anaerobic metabolism to maintain their energy homeostasis for maximum survival. The present study provides great insights into the molecular and metabolic strategies of intertidal shellfish in response to salinity stress, and uncovers the new potential signaling metabolites to assess the health states of molluscs in aquaculture.

Characterization of a West African Coastal Lagoon System: Case of Lake Nokoué with Its Inlet (Cotonou, South Benin)

The purpose of this work was to investigate the physical and chemical dynamics of Lake Nokoué for its efficient management. For this purpose, two sampling campaigns per month from five stations (North, South, Central, East and West) were conducted for a period of one year (November 2020 to November 2021). Physic and chemical parameters (temperature, salinity, depth, water transparency, pH, dissolved oxygen and total dissolved solids) were measured and wet substrate samples were collected to study the granulometry. Data analysis revealed that Lake Nokoué is mainly affected by two regimes: flooding and low water. Flooding, which is not directly related to rainfall, did not begin until one month after the major rainy season in June. The sources that contributed to the flooding of Lake Nokoué were the freshwater tributaries coming mainly from the Ouèmé River and the flow of the Sô River from August to November. The inflow of fresh water contributed to the decrease in salinity and transparency of the lake from the east to the south. During the low water period (from December to July), Lake Nokoué is characterized by an increase in salinity and transparency from the south to the northeast due to the massive intrusion of sea water into the lake. The highest dissolved oxygen levels are observed in the south and center (5.92 ± 0.46 mg/L) while it varies greatly in the north and west (Eichhornia crassipes concentration zone) during flooding. The average annual depth of Lake Nokoué was 1.47 ± 0.66 m with an average annual pH of 6.85 ± 0.56.

The Control of Sea Level Change over the Development of Favorable Sand Bodies in the Pinghu Formation, Xihu Sag, East China Sea Shelf Basin

The Pinghu Formation consists primarily of marine-continental transitional deposits. The widely distributed fluvial and tidal transgressive sand bodies comprise the main reservoirs of the Baochu slope zone in the Xihu Sag in the East China Sea Shelf Basin. These sand bodies are deeply buried, laterally discontinuous, and are frequently interrupted by coal-bearing intervals, thereby making it extremely difficult for us to characterize their hydrocarbon potential quantitatively via seismic inversion techniques, such as multi-attribute seismic analysis and post-stack seismic inversion, hindering further hydrocarbon exploration in the Xihu Sag. Here, a prestack seismic inversion approach is applied to the regional seismic data to decipher the spatiotemporal distribution pattern of the sand bodies across the four sequences, i.e., SQ1, SQ2, SQ3, and SQ4, from bottom up, within the Pinghu Formation. In combination with detailed petrology, well log, and seismic facies analysis, the secular evolution of the sedimentary facies distribution pattern during the accumulation of the Pinghu Formation is derived from the sand body prediction results. It is concluded that the sedimentary facies and sand body distribution pattern rely on the interplay between the hydrodynamics of fluvial and tidal driving forces from the continent and open ocean, respectively. Drops in the sea level led to the gradual weakening of tidal driving forces and relative increases in riverine driving forces. The direction of the sand body distribution pattern evolves from NE–SW oriented to NW–SE oriented, and the dominant sand body changes from tidal facies to fluvial facies. In addition, the sea level drop led to the decrease in the water column salinity, redox condition, organic matter composition, and the development of coal seams, all of which directly influenced the quality of reservoir and source rocks. The sand bodies in SQ2 and SQ3 are favorable reservoirs in the Pinghu Formation due to their good reservoir properties and great thickness. The high-quality source rock in SQ1 could provide significant hydrocarbons and get preserved in the sand body within SQ2 and SQ3. This contribution provides an insight into the control of the sea level change over the development of hydrocarbon reservoirs in the petroleum system from marginal-marine environments such as the Xihu Sag.

Effects of short-term hyposalinity stress on four commercially important bivalves: A proteomic perspective

Increased heavy rainfall can reduce salinity to values close to 0 in estuaries. Lethal and sublethal physiological and behavioural effects of decreases in salinity below ten have already been found to occur in the commercially important clam species Venerupis corrugata, Ruditapes decussatus and R. philippinarum and the cockle Cerastoderma edule, which generate an income of ∼74 million euros annually in Galicia (NW Spain). However, studies of the molecular response to hyposaline stress in bivalves are scarce. This ‘shotgun’ proteomics study evaluates changes in mantle-edge proteins subjected to short-term hyposaline episodes in two different months (March and May) during the gametogenic cycle. We found evidence that the mantle-edge proteome was more responsive to sampling time than to hyposalinity, strongly suggesting that reproductive stages condition the stress response. However, hyposalinity modulated proteome profiles in V. corrugata and C. edule in both months and R. philippinarum in May, involving proteins implicated in protein folding, redox homeostasis, detoxification, cytoskeleton modulation and the regulation of apoptotic, autophagic and lipid degradation pathways. However, proteins that are essential for an optimal osmotic stress response but which are highly energy demanding, such as chaperones, osmoprotectants and DNA repair factors, were found in small relative abundances. In both months in R. decussatus and in March in R. philippinarum, almost no differences between treatments were detected. Concordant trends in the relative abundance of stress response candidate proteins were also obtained in V. corrugata and C. edule in the different months, but not in Ruditapes spp., strongly suggesting that the osmotic stress response in bivalves is complex and possibly influenced by a combination of controlled (sampling time) and uncontrolled variables. In this paper, we report potential molecular targets for studying the response to osmotic stress, especially in the most osmosensitive native species C. edule and V. corrugata, and suggest factors to consider when searching for biomarkers of hyposaline stress in bivalves.

The effect of water salinity on the effectiveness of oil dispersants

A comparative evaluation of the effectiveness of the industrially produced oil spill dispersants (Finasol OSR 52 (France), Slickgone NS and Slickgone EW (United Kingdom)) was carried out. The effectiveness of dispersants was assessed using three samples of domestic crude oil with different physical and chemical properties (extra light, heavy, and bituminous oil) in water samples of various salinity. An adapted version of ASTM F2059–17 «Standard Test Method for Laboratory Oil Spill Dispersant Effectiveness Using the Swirling Flask» (the so-called SFT test) was used for evaluation. The low-energy technique was chosen to determine conditionally lower limits of the dispersant effectiveness. Comparative tests were carried out at the highest dispersant-to-oil ratio 1:10 allowed in the Russian Federation (according to STO 318.4.02–2005 «Rules of dispersant application for oil spill response»), water temperature 20°C and water salinity 0, 5, 10, 20, and 35‰. It is shown that the dispersants are poorly effective in dispersing the considered oil samples at water salinity 35‰. A general trend of increasing the dispersant effectiveness with a decrease in water salinity is demonstrated. It is shown that all tested dispersants are not suitable for application in the studied range of water salinity in the event of spill of the bituminous oil with a high content of asphaltenes and polar compounds. For all dispersants, the limits of their application are determined depending on the salinity of water. The effectiveness value equal to 45 % legally approved in the USA and Mexico was taken as a threshold value. The revealed lack of the dispersant versality necessitates preliminary experimental testing using a sample of spilled oil under climatic and hydrochemical conditions corresponding to the potential area of their application.

Steroidogenic Effects of Salinity Change on the Hypothalamus-Pituitary-Gonad (HPG) Axis of Male Chinese Sea Bass (Lateolabrax maculatus).

As lower vertebrates, teleost species could be affected by dynamic aquatic environments and may respond to environmental changes through the hypothalamus–pituitary–gonad (HPG) axis to ensure their normal growth and sexual development. Chinese sea bass (Lateolabrax maculatus), euryhaline marine teleosts, have an extraordinary ability to deal with a wide range of salinity changes, whereas the salinity decrease during their sex-maturation season may interfere with the HPG axis and affect their steroid hormone metabolism, resulting in abnormal reproductive functioning. To this end, in this study, 40 HPG axis genes in the L. maculatus genome were systematically characterized and their copy numbers, phylogenies, gene structures, and expression patterns were investigated, revealing the conservation of the HPG axis among teleost lineages. In addition, freshwater acclimation was carried out with maturing male L. maculatus, and their serum cortisol and 11-ketotestosterone (11-KT) levels were both increased significantly after the salinity change, while their testes were found to be partially degraded. After salinity reduction, the expression of genes involved in cortisol and 11-KT synthesis (cyp17a, hsd3b1, cyp21a, cyp11c, hsd11b2, and hsd17b3) showed generally upregulated expression in the head kidneys and testes, respectively. Moreover, cyp11c and hsd11b2 were involved in the synthesis and metabolism of both cortisol and 11-KT, and after salinity change their putative interaction may contribute to steroid hormone homeostasis. Our results proved the effects of salinity change on the HPG axis and steroidogenic pathway in L. maculatus and revealed the gene interactions involved in the regulation of steroid hormone levels. The coordinated interaction of steroidogenic genes provides comprehensive insights into steroidogenic pathway regulation, as well as sexual development, in teleost species.

Effects of low-salinity acclimation on the Na+/K+ ATPase activity and expression of osmoregulatory-related genes in large yellow croaker (Larimichthys crocea)

Large yellow croaker (Larimichthys crocea) is one of the most commercially important marine fish in southeast China. The white spot disease frequently occurs in large yellow croaker leading to a devastating loss. Given that the pathogen, Cryptocaryon irritans, hardly survive in the low-salinity environment, the low-salinity farming is a potential strategy to defend large yellow croaker. In this study, the water salinity was consecutively decreased from 28 ‰ to 0 ‰, during which the survival rate of L. crocea was stable from 28 ‰ to 4 ‰, while a higher mortality was observed at < 4 ‰. The NKA activity in the kidney and gill of L. crocea was significantly stimulated by the decrease of water salinity from 28 ‰ to 4 ‰ and gradually dropped to the baseline, which was associated with variations of the expression level of NKAα1 and NKAβ1. The expression profile of PRLR was consistent with NKAα1 and NKAβ1, which implied that they might be the targets of PRL in L. crocea in response to the challenge of salinity variations. The other two osmoregulatory-related genes, NHEβ and NCC, significantly increased at low water salinity (< 4 ‰) in both the kidney and gill, which likely dedicated the sodium reabsorption at low water salinity. Our findings would provide new insights into osmoregulation of the kidney and gill in the large yellow croaker in response to the challenge of lowing water salinity.