Optimal Salinity Research Articles

Hybridization and growth characteristics of interspecific crosses between Crassostrea hongkongensis and Crassostrea iredalei

Interspecific hybridization of oysters is a highly efficient breeding strategy that can produce commercially viable phenotypes. Crassostrea hongkongensis, the primary cultivar in southern China, faces increasing summer mortality risks and slow growth rates, which elevate commercial risks for farmers. C. iredalei, a commercially cultivated species in Southeast Asia, has been expanding its ecological niche northward in recent years, providing opportunities for interspecific hybridization with C. hongkongensis. This study conducted a 2 × 2 factorial cross between C. hongkongensis and C. iredalei (II: C. iredalei ♀ × C. iredalei ♂, HH: C. hongkongensis ♀ × C. hongkongensis ♂; IH: C. iredalei ♀ × C. hongkongensis ♂, HI: C. hongkongensis ♀ × C. iredalei ♂) and set up 6 salinity treatments (14, 17, 20, 23, 26 and 29 ppt) to explore the optimal salinity for embryo hatching. The results showed that the hybridization was successful, despite bidirectional fertilization and pronounced asymmetry in fertilization success. The optimal hatching salinity for C. iredalei and C. hongkongensis was 23 ppt and 17–20 ppt, respectively, while the optimal salinity for reciprocal hybrids was 20 ppt. Notably, the hatching rate of IH was lower than that of the control group at the optimal salinity. During the pelagic larval stage, hybrid larvae exhibited significant hybrid inferiority, with slower growth rates and higher mortality rates compared to intraspecific hybridization. It is worth noting that IH failed to overcome genetic incompatibility, resulting in complete mortality during the pelagic larval stage and failure to enter the growth stage. At the 360th day of the growth period, HI hybrids grown in Sanbaimen Sea exhibited significant hybrid vigor in shell height (15.65 %), and in Daya Bay Marine Biology Research Station, Chinese Academy of Sciences (MBRS), they showed significant single-parent hybrid advantages in shell height (28.44 %) and cumulative survival rate (58.11 %) compared to C. hongkongensis. In terms of gonadal development, HI hybrids were able to produce functional and viable gametes, although with some delay compared to their parents. The hybrid offspring inherited the phenotypic traits of their parents, with a grayish-yellow flesh color intermediate between the two oyster species. HI is a valuable genetic resource for oyster breeding, and its growth potential should be further explored to meet commercialization demands.

Prevalence of <i>Vibrio parahaemolyticus</i>, <i>Vibrio cholerae</i>, and <i>Vibrio alginolyticus</i> in a White-leg Shrimp (<i>Litopenaeus vannamei</i>) Farm in Sarawak

Vibriosis in shrimp farms poses potential risks to the industry’s sustainability and the consumers’ health. Little is known about the dynamics and variation of <i>Vibrio</i> spp—population in shrimp production in Sarawak, Malaysia. The apparent prevalence of three <i>Vibrio</i> species, <i>V. parahaemolyticus</i>, <i>V. cholerae</i>, and <i>V. alginolyticus</i>, were investigated in water (n=12), sediment (n=12), shrimp (n=12), and effluent (n=12) samples collected from two ponds in a coastal shrimp farm during one production cycle. Multiplex-PCR using specific primer sets showed the presence of the three Vibrio species. Based on the results, <i>V. parahaemolyticus</i> was the most prevalent in all four samples, with a contamination rate of 97.92% (95% CI: 89. 10 to 99.89%), while <i>V. cholerae</i> and <i>V. alginolyticus</i> had a contamination rate of 47.92% (95% CI: 34.37 to 61.67%) and 25.0% (95% CI: 14.92 to 38.78%), respectively. High <i>Vibrio</i> load in the shrimp farm is due to favourable environmental factors, such as optimal temperatures, salinity, and pH ranges for the growth of these species. The study’s findings offer important preliminary insights into the prevalence and distribution of these pathogenic <i>Vibrio</i> spp., within a shrimp farm in Kuching, Sarawak. This study serves as a potential model for monitoring <i>Vibrio</i> spp. prevalence in other shrimp farms across Sarawak, thereby addressing the scarcity of data on prevalence in the region.

In silico and experimental characterization of a new polyextremophilic subtilisin-like protease from Microbacterium metallidurans and its application as a laundry detergent additive.

Considering the current growing interest in new and improved enzymes for use in a variety of applications, the present study aimed to characterize a novel detergent-stable serine alkaline protease from the extremophilic actinobacterium Microbacterium metallidurans TL13 (MmSP) using a combined in silico and experimental approach. The MmSP showed a close phylogenetic relationship with high molecular weight S8 peptidases of Microbacterium species. Moreover, its physical and chemical parameters computed using Expasy's ProtParam tool revealed that MmSP is hydrophilic, halophilic and thermo-alkali stable. 3D structure modelling and functional prediction of TL13 serine protease resulted in the detection of five characteristic domains: [catalytic subtilase domain, fibronectin (Fn) type-III domain, peptidase inhibitor I9, protease-associated (PA) domain and bacterial Ig-like domain (group 3)], as well as the three amino acid residues [aspartate (D182), histidine (H272) and serine (S604)] in the catalytic subtilase domain. The extremophilic strain TL13 was tested for protease production using agricultural wastes/by-products as carbon substrates. Maximum enzyme activity (390U/gds) was obtained at 8th day fermentation on potato peel medium. Extracellular extract was concentrated and partially purified using ammonium sulfate precipitation methodology (1.58 folds purification fold). The optimal pH, temperature and salinity of MmSP were 9, 60°C and 1M NaCl, respectively. The MmSP protease showed broad pH stability, thermal stability, salt tolerance and detergent compatibility. In order to achieve the maximum stain removal efficacy by the TL 13 serine protease, the operation conditions were optimized using a Box-Behnken Design (BBD) with four variables, namely, time (15-75min), temperature (30-60°C), MmSP enzyme concentration (5-10U/mL) and pH (7-11). The maximum stain removal yield (95 ± 4%) obtained under the optimal enzymatic operation conditions (treatment with 7.5U/mL of MmSP during 30min at 32°C and pH9) was in good agreement with the value predicted by the regression model (98 ± %), which prove the validity of the fitted model. In conclusion, MmSP appears to be a good candidate for industrial applications, particularly in laundry detergent formulations, due to its high hydrophilicity, alkali-halo-stability, detergent compatibility and stain removal efficiency.

Development of surfactant formulation for high-temperature off-shore carbonate reservoirs.

The residual oil left behind after water flooding in petroleum reservoirs can be mobilized by surfactant formulations that yield ultralow interfacial tension (IFT) with oil. However, finding ultralow IFT surfactant formulations is difficult for high-temperature, off-shore, carbonate reservoirs. These reservoirs are often water-flooded with seawater (with a lot of divalent ions), which is often incompatible with many surfactants at high temperatures. The goal of this research is to develop a surfactant formulation for an off-shore carbonate reservoir at 100°C previously flooded by seawater. Surfactant-oil-brine phase behavior was studied for formulations, starting from a single surfactant to mixtures of surfactants and a co-solvent. Mixtures of three surfactants and one co-solvent were needed to produce ultralow IFT formulations for the oil of interest. The surfactant system with polymer mobility control was tested in crushed reservoir rock packs. The cumulative oil recovery was >99% for the surfactant-polymer (SP) flood with an optimal salinity gradient. The constant salinity SP floods with seawater increased oil recovery significantly beyond the water flood (cumulative oil recovery >91%), even though the recovery was lower than that of the optimal salinity gradient SP flood. Our experimental work demonstrates the effectiveness of the surfactant formulation for a high-temperature carbonate reservoir at seawater salinity.

Integration between experimental investigation and numerical simulation of alkaline surfactant foam flooding in carbonate reservoirs

In Brazil, pre-salt carbonate reservoirs are largely responsible for the current increase in oil production. However, due to its peculiar characteristics, increasing oil recovery by water injection is not enough. Therefore, we seek to evaluate the recovery potential using chemical methods (cEOR). Among these, the Alkali Surfactant Foam (ASF) method appears with high potential, a variant of Alkali Surfactant Polymers (ASP) without the problems presented by it. Therefore, this work presents an innovative methodology, which seeks to evaluate the potential for recovery with ASF in carbonate reservoirs by integrating experimental characterization and recovery prediction using reservoir simulation. For this, phase behavior and adsorption analyses were carried out. The experimental results provided key parameters for the simulation, such as optimal salinity, surfactant adsorption, foam mobility reduction factors. The results are from two case studies of AS and ASF flooding, using a section of UNISIM-II benchmark, using a one-quarter of five-spot model. Having the modelling for these cEOR methods defined, an optimization process for each method was applied, allowing a reliable comparison among the methods and over a base case of water injection, seeking the maximization of the net present value (NPV). As a result, in the experimental part, a low interfacial tension (IFT) value of 0.003 mN/m was achieved with a surfactant adsorption reduction of 17.9% for an optimal setting among brine (NaCl), alkali (NaBO2.4H2O), and surfactant (BIO-TERGE AS 40). In the reservoir simulation part, using a fast genetic algorithm in the optimization process, a NPV of US$ 14.43 million higher than the base case (water injection) and a 4.5% increase in cumulative oil production for the ASF injection case were obtained. Considering the analyses of production curves (cumulative oil production and oil rate) and oil saturation maps, a considerable oil production anticipation was observed, which was the main reason for NPV improvement, proving the high potential for application of the ASF method in carbonate reservoirs.

Low salinity stress increases the risk of Vibrio parahaemolyticus infection and gut microbiota dysbiosis in Pacific white shrimp

BackgroundExtreme precipitation events often cause sudden drops in salinity, leading to disease outbreaks in shrimp aquaculture. Evidence suggests that environmental stress increases animal host susceptibility to pathogens. However, the mechanisms of how low salinity stress induces disease susceptibility remain poorly understood.MethodsWe investigated the acute response of shrimp gut microbiota exposed to pathogens under low salinity stress. For comparison, shrimp were exposed to Vibrio infection under two salinity conditions: optimal salinity (Control group) and low salinity stress (Stress group). High throughput 16S rRNA sequencing and real-time PCR were employed to characterize the shrimp gut microbiota and quantify the severity level of Vibrio infection.ResultsThe results showed that low salinity stress increased Vibrio infection levels, reduced gut microbiota species richness, and perturbed microbial functions in the shrimp gut, leading to significant changes in lipopolysaccharide biosynthesis that promoted the growth of pathogens. Gut microbiota of the bacterial genera Candidatus Bacilliplasma, Cellvibrio, and Photobacterium were identified as biomarkers of the Stress group. The functions of the gut microbiota in the Stress group were primarily associated with cellular processes and the metabolism of lipid-related compounds.ConclusionsOur findings reveal how environmental stress, particularly low salinity, increases shrimp susceptibility to Vibrio infection by affecting the gut microbiota. This highlights the importance of avoiding low salinity stress and promoting gut microbiota resilience to maintain the health of shrimp.

Rapid design and optimization of complex surfactant microemulsions for high-efficiency oil extraction processes integrating experimental and modeling approaches

Microemulsions have been widely used as a means of high-efficiency oil extraction processes in the field of oil recovery, separation, deposit removal, et al. Phase behavior is considered the most reliable evidence for formulating surfactant systems. There, however, few methods exist that can predict the phase behavior of microemulsions formed by complex surfactant compositions.This work developed a modified model based on the Hydrophilic Lipophilic Deviation-Net Average Curvature (HLD-NAC) model that could rapidly and accurately predict the phase behavior and phase evolution of complex surfactant microemulsions. The phase evolution of the microemulsions with equivalent alkane carbon number (EACN), surfactant concentration, and water–oil ratio (WOR) were explored. The results indicated that the new model successfully delineated the salinity boundaries of Winsor Type III microemulsion and predicted the inversions of phase behavior. A linear correlation between the EACN and the optimal salinity was demonstrated, with a precisely defined predictive range of EACN for Winsor Type III microemulsions. A fish diagram that illustrated the evolution path of the microemulsion phase was established through concentration scanning. The WOR test suggested that Winsor Type III microemulsion could be formed through salinity regulation once the surfactant concentration exceeded the critical micelle concentration (CMC).

Cognatishimia coralii sp. nov., a marine bacterium isolated from seawater surrounding corals.

Coral reefs are declining due to the rising seawater temperature. Bacteria within and surrounding corals play key roles in maintaining the homeostasis of the coral holobiont. Research on coral-related bacteria could provide benefits for coral reef restoration. During the isolation of coral-associated bacteria, a Gram-stain-negative, motile bacterium (D5M38T) was isolated from seawater surrounding corals in Daya Bay, Shenzhen, PR China. Phylogenetic analysis revealed that strain D5M38T represents a novel species in the genus Cognatishimia. The temperature range for strain D5M38T growth was 10-40 °C, and the optimum temperature was 37 °C. The salinity range for the growth of this isolate was from 0 to 4.0 %, with an optimal salinity level of 0.5 %. The pH range necessary for strain D5M38T growth was between pH 5.0 and 9.0, with an optimal pH being 7.5. The predominant fatty acid was summed feature 8 (65.0 %). The major respiratory quinone was Q-10. The DNA G+C content was 56.8 %. The genome size was 3.88 Mb. The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values between strain D5M38T and its two closest neighbours, Cognatishimia activa LMG 29900T and Cognatishimia maritima KCTC 23347T, were 73.2/73.6%, 73.2/73.6% and 19.7/19.5%, respectively. Strain D5M38T was clearly distinct from its closest neighbours C. activa LMG 29900T and C. maritima KCTC 23347T, with 16S rRNA gene sequence similarity values of 97.5 and 97.3 %, respectively. The phylogenetic analysis, along with the ANI, AAI, and dDDH values, demonstrated that strain D5M38T is a member of the genus Cognatishimia, and is distinct from the other two recognized species within this genus. The physiological, biochemical and chemotaxonomic characteristics also supported the species novelty of strain D5M38T. Thus, strain D5M38T is considered to be classified as representing a novel species in the genus Cognatishimia, for which the name Cognatishimia coralii sp. nov. is proposed. The type strain is D5M38T (=MCCC 1K08692T=KCTC 8160T).

A non‐ionic green surfactant extracted from the Anabasis setifera plant for improving bulk properties of CO2‐foam in the process of enhanced oil recovery from carbonate reservoirs

AbstractFoam, as a gas‐in‐liquid colloid, has a higher appearance viscosity than the one of both gas and liquid that form it. Adjusting the mobility ratio of the injected fluid–oil system and increasing gas diffusion in the foam injection process increase oil production. With these properties, foam as an injection fluid in fractured reservoirs has a major effect on oil production from the matrixes and prevents premature production of injection fluid. Surfactants are common foaming agents in injection water. Saponins are known as plant‐derived surfactants for forming stable foam. This feature, along with its cheap price and availability, can make them candidates for enhanced oil recovery (EOR) by the foam injection method. However, the utilization of CO2 as the gaseous phase in foam introduces additional machanisms of CO2 injection to the oil recovery operations. In this assessment, a non‐ionic green surfactant derived from the Anabasis setifera plant was used as a foaming agent, while CO2 served as the gas phase. A series of surface tension tests in CO2 environment were performed to determine the optimal concentration of the surfactant. Foaming tests were performed by a designed foam generator. The produced CO2‐foam was then injected into a fractured carbonate plug with six matrixes (with one horizontal and two vertical fractures). Based on the results, the water–CO2 surface tension was reduced to 20.549 mN/m. The optimum salinity based on the foam stability was 10,000 ppm. The half‐life of the foam was determined to be 40 min. Also, the foam characterization showed that the foamability of the surfactant was favourable for increasing oil production so that by secondary flooding, an oil recovery of more than 66% was achieved from the fractured carbonate plug.

Assessing Salinity Reduction by Environmental Restoration in the Seomjin River Estuary (South Korea): A Numerical Model Approach for Corbicula Habitat Conservation

This study modelled possible ways of reducing salinity in the Seomjin River estuary to improve habitats for corbicula, which are important components of the ecosystem (ecologically and commercially) in the Seomjin River. Additionally, we analyzed the salinity reduction effects of structural measures to sustain optimal salinity. To do this, salinity measurement facilities were installed at crucial habitat locations in the Seomjin River estuary. After ensuring the reliability of the model, numerical simulations were conducted. Salinity changes were analyzed for four major locations (Dugok, Shinbi, Mokdo, Hwamok) and simulated under various conditions, resulting in concentrations of 4.7 psu in Dugok, 16.0 psu in Shinbi, 19.2 psu in Mokdo, and 28.2 psu in Hwamok. Additionally, this study analyzed reduction effects by applying three reduction scenarios (riverbed restoration, submerged weir, and groyne) by simulating the numerical model. The reductions in salinity for the submerged weir (SWS-1 to 3) and groyne (GS-1 to 3) scenarios were minimal, below 1 psu, indicating a very limited reduction effect. In conclusion, the salinity concentration in the Seomjin River estuary is dominated by the neap tide, and the salinity intrusion distance is influenced more by the spring tide. The Songjeong discharge strongly impacts the spring tide, while the neap tide is less dominant due to salinity stratification. Among the salinity reduction scenarios, riverbed restoration has the most critical effect, but artificial reduction measures may pose challenges in terms of cost and practicality.

Detection of soil salinity distribution and its change in the Yellow River Delta comparing 2006 and 2022

AbstractThe Yellow River Delta (YRD) has the world's highest land formation rate. However, soil salinization has caused severe land degradation in the region. Understanding the distribution of soil salinity and its variation is essential for saline soil management. This study combined soil salinity sampling data, remote sensing imagery, and layers of geographic environmental factors. Three different models, including Ordinary Kriging (OK), Geographically Weighted Regression (GWR), and Bayesian Maximum Entropy (BME), were used and compared to predict the soil salinity of two soil layers in 2006 and 2022. Then the spatial distribution characteristics and development trends of soil salinity in the YRD were analyzed. The results indicated that (1) The BME model is an optimal salinity prediction model that integrates soft data from multiple sources to perform nonlinear estimates. Compared to the OK and GWR models, the RMSE was reduced by up to 25% and 13%, respectively, and the greatest improvement in R2 was increased from 0.0534 and 0.2718 to 0.5569, respectively. (2) Soil salinity in the YRD shows a spatially increasing trend from the southwestern inland to the northeastern coast. Over the past 16 years, the salinization pattern has become more complex: soil salinization has been mitigated in the central and southern regions, with the average salinity decreasing from 1.03% to 0.86% and the salinization rate decreasing from 99% to 88%; and it has significantly intensified in the northern part of the study area near the old Yellow River channel and the Gubei Reservoir, and in some scattered inland areas. Continuous water and sediment regulation in the Yellow River basin and ecological management of natural reserves can generally alleviate soil salinization, but the risk of soil salinization can be increased by seawater erosion, inappropriate land use, and resource exploitation.

Exploring interfacial properties and thermodynamic parameters of synthesized biodegradable surfactants from Brassica Juncea and their emulsification characteristics

This study investigates the synthesis and characterization of four non-ionic surfactants of different spacer lengths derived from Brassica Juncea (mustard oil) and explore their potential applications. The chemical structures of the surfactants were confirmed by FTIR, 1HNMR spectroscopy and GC. Surface tension values of the surfactants were measured at various temperatures, unveiling temperature-dependent behaviour and associated thermodynamics. The critical micelle concentrations (CMC) of different surfactants were found to be very low (0.064–0.096 mmol/l at 303 K) compared to conventional surfactants. The CMC and the surface tension further decrease significantly with an increase in temperature. Surface-active thermodynamic parameters of the surfactants demonstrate their lower interfacial characteristics and enhanced self-aggregation capability. At CMC, the synthesized surfactants effectively decrease the interfacial tension (IFT) between water and dodecane to a notably low range of 9.5 to 12.1 mN/m, which is further reduced to a range of 3.2 to 6.1 mN/m at optimal salinity. The surfactants also show good emulsification properties, the emulsions formed in the water-dodecane system using the gemini surfactants as emulsifiers were extensively characterized, encompassing phase behaviour and droplet size distribution analysis. These emulsions exhibit favourable viscous properties, with viscosities ranging from 5 to 20 mPa.s at a 5 s-1 shear rate. This study establishes that the synthesized Gemini surfactants are viable candidates for Enhanced Oil Recovery (EOR), showcasing robust stability, interfacial activity, and favourable rheological properties, alongside biodegradability.

Naturally and Anthropogenically Induced Lingulodinium polyedra Dinoflagellate Red Tides in the Galician Rias (NW Iberian Peninsula).

Despite the fact that the first red tide reported on the coasts of the Iberian Peninsula was due to Lingulodinium polyedra, knowledge about their frequency and, particularly, about the environmental conditions contributing to bloom initiation is still scarce. For this reason, L. polyedra bloom episodes were observed and studied in three Galician rias during the summer season based on the 1993-2008 record database period; additionally, samples were collected in summer 2008. Proliferations of L. polyedra occurred in the rias of Ares and Barqueiro in June and August, respectively, while in the Ria of Coruña, they persisted from the end of June to early September. Red tides developed when the surface temperature reached 17 °C, with "seasonal thermal window" conditions, and when salinities were ≥30, i.e., an "optimal salinity window"; when these parameters were lower than these thresholds, cyst germination decreased. A cyst transport mechanism from sediments to the surface must also exist; this mechanism was found to be natural (tidal currents) in the ria of Barqueiro or anthropogenic (dredging) in the rias of Ares and Coruña. Surface temperatures during summer were usually favorable for cyst germination (85 to 100%) during the 1993-2008 period; however, water temperatures below 10 m depth only rarely reached the 17 °C threshold (2 to 18%). During this 16-year period, dredging activities could explain 71% (Coruña) and 44% (Ares) of the recorded bloom events. When a bloom episode developed in early summer, favorable conditions did not lead to a new red tide, probably due to the lag period required by cysts for germination. Moreover, blooms did not develop when high densities of diatoms (>1,000,000 cells·L-1) remained in the water column as a result of summer upwelling pulses occurring in specific years. The temperature-sediment disturbance pattern found in this study provides a useful tool for the prevention of eventual risks resulting from red tides of this dinoflagellate.

Salt thickening performance and mechanism of an N-Vinyl-2-Pyrrolidinone based amphiphilic polymer

Enhancing salt tolerance is a critical requirement for polymer flooding in the petroleum production process. This work introduced a novel salt thickening polymer called NDC16, which is a cationic polymer composed of poly(N-Vinyl-2-Pyrrolidinone-co-Double hexadecyldimethylallyl ammonium chloride). Notably, NDC16 does not contain traditional Acrylamide (AM) or Acrylic acid (AA). Its salt thickening performance and mechanism in sodium chloride and calcium chloride solutions were separately analyzed at aggregation and molecular levels by photophysical method, micromorphology, and molecular dynamics (MD) simulation. The results demonstrated that the novel polymer was able to increase the viscosity of the sodium chloride solution to 20 times higher than the initial one. However, its performance in increasing viscosity in a calcium chloride solution was only half as effective. The inclusion experiments indicated that almost all increasing viscosity could be contributed to the hydrophobic association effects of the polymer molecules. The results of the dynamic analysis revealed that the NDC16 aggregates showed a more orderly arrangement in NaCl solutions, while the network structure appeared as relatively disordered clusters in CaCl2. Besides, there existed an optimal salinity at which the network density of the hydrophobic structure reached the highest level. The variation in thickening performance can be elucidated by the molecular interaction. Due to their smaller molecular interactions, the Na+ ions exhibited a stronger potential to permeate into the polymer clusters. It stretched the polymer molecules and allowed them to display a structured arrangement. The large Radius of Gyration (Rg) and spatial distance of the polymers in two solutions indicated that the polymer clusters were much elongated in Na+ solvents, thereby confirming their permeation effect. These results enhance the comprehension of the process by which salt thickening occurs due to the interaction between cationic hydrophobic associative polymers and various salt solutions.

Assessment of spawning habitat suitability for Amphidromous Ayu (Plecoglossus altivelis) in tidal Asahi River sections in Japan: Implications for conservation and restoration

AbstractThe Amphidromous Ayu (Plecoglossus altivelis), vital for Japan's riverine commercial fisheries, is experiencing population decline due to habitat degradation. In response, Japan is implementing restoration efforts by releasing juvenile fish and cultivating spawning habitats. This study, focusing on the Asahi River's Heidan area, evaluates Ayu spawning habitat suitability, especially in tidal zones, and its conservation implications. Through field surveys and numerical analysis, the research identifies optimal conditions for spawning amid dwindling numbers. Observations from the 2020 peak spawning season showed that water temperatures below 20°C are conducive to spawning, with the best sites producing up to 48,817 eggs/m2. Gravel sizes between 0.85 and 53.0 mm were identified as crucial for effective spawning. Notably, artificial spawning grounds established in 2019 showed no spawning activity, likely due to saline intrusion from tides. Using the three‐dimensional hydrodynamic‐aquatic ecosystem numerical model, the study assesses flow, substrate, and water quality's impact on spawning, corroborated by sensor data. A key finding is the negative correlation between salinity and egg density in tidal sections of the Asahi River. Furthermore, an artificial intelligence (AI)‐based YOLOv5 model, trained on underwater images, effectively detected Ayu aggregations, demonstrating an F1‐score of 0.757 in differentiating Ayu from other coexisting fish species in the same aquatic environment. This AI approach provides a nonintrusive method for monitoring Ayu populations and habitat preferences. The research underlines that successful spawning habitats require minimal saline intrusion, with optimal salinity and flow conditions. These insights are critical for spawning ground development, emphasizing the management of tidal effects and riverbed conditions to bolster Ayu populations and preserve aquatic ecosystems.

Optimal conditions and nitrogen removal performance of aerobic denitrifier Comamonas sp. pw-6 and its bioaugmented application in synthetic domestic wastewater treatment.

To assess the possibility of using aerobic denitrification (AD) bacteria with high NO2--N accumulation for nitrogen removal in wastewater treatment, conditional optimization, as well as sole and mixed nitrogen source tests involving AD bacterium, Comamonas sp. pw-6 was performed. The results showed that the optimal carbon source, pH, C/N ratio, rotational speed, and salinity for this strain were determined to be succinate, 7, 20, 160 rpm, and 0%, respectively. Further, this strain preferentially utilized NH4+-N, NO3--N, and NO2--N, and when NO3--N was its sole nitrogen source, 92.28% of the NO3--N (150 mg·L-1) was converted to NO2--N. However, when NH4+-N and NO3--N constituted the mixed nitrogen source, NO3--N utilization by this strain was significantly lower (p < 0.05). Therefore, a strategy was proposed to combine pw-6 bacteria with traditional autotrophic nitrification to achieve the application of pw-6 bacteria in NH4+-N-containing wastewater treatment. Bioaugmented application experiments showed significantly higher NH4+-N removal (5.96 ± 0.94 mg·L-1·h-1) and lower NO3--N accumulation (2.52 ± 0.18 mg·L-1·h-1) rates (p < 0.05) than those observed for the control test. Thus, AD bacteria with high NO2--N accumulation can also be used for practical applications, providing a basis for expanding the selection range of AD strains for wastewater treatment.

Effects of Salt Water on Growth and Quality of Raphanus sativus L. and Physiological Responses against Salt Stress

To determine the optimal salinity of irrigation water for fruit radish cultivated in peat, five levels of salinized water were used to evaluate their effect on the growth and quality of fruit radish (Raphanus sativus L.). Results showed that with an increase in salinity, the leaf growth was somehow inhibited, but the fleshy root growth increased, and quality improved with more soluble solids, sugar, protein, and Vitamin C substances in fleshy roots. With an increase in water salinity up to 4.2 dS/m, the weight of fleshy roots increased by 51.10% with a high increment in the root/shoot ratio. With the same salt concentration, the content of soluble solids in both root peal and pulp was the highest and improved by 11.06% and 6.70%, respectively. The soluble sugar content was the highest in root peals with the 4.2 dS/m treatment and in fleshy roots with the 7.4 dS/m treatment, with a 55.85% and 32.30% increase, respectively. The content of both soluble protein and vitamin C with the 4.2 dS/m treatment increased by 11.99% and 113.36%, respectively. Strong evidence derived from the study has indicated that 4.2 dS/m salinized irrigation water is optimal for growing ‘ice-cream’ fruit radishes and maintaining ultimate root weight and quality.

Thriving under Salinity: Growth, Ecophysiology and Proteomic Insights into the Tolerance Mechanisms of Obligate Halophyte Suaeda fruticosa.

Studies on obligate halophytes combining eco-physiological techniques and proteomic analysis are crucial for understanding salinity tolerance mechanisms but are limited. We thus examined growth, water relations, ion homeostasis, photosynthesis, oxidative stress mitigation and proteomic responses of an obligate halophyte Suaeda fruticosa to increasing salinity under semi-hydroponic culture. Most biomass parameters increased under moderate (300 mmol L-1 of NaCl) salinity, while high (900 mmol L-1 of NaCl) salinity caused some reduction in biomass parameters. Under moderate salinity, plants showed effective osmotic adjustment with concomitant accumulation of Na+ in both roots and leaves. Accumulation of Na+ did not accompany nutrient deficiency, damage to photosynthetic machinery and oxidative damage in plants treated with 300 mmol L-1 of NaCl. Under high salinity, plants showed further decline in sap osmotic potential with higher Na+ accumulation that did not coincide with a decline in relative water content, Fv/Fm, and oxidative damage markers (H2O2 and MDA). There were 22, 54 and 7 proteins in optimal salinity and 29, 46 and 8 proteins in high salinity treatment that were up-regulated, down-regulated or exhibited no change, respectively, as compared to control plants. These data indicate that biomass reduction in S. fruticosa at high salinity might result primarily from increased energetic cost rather than ionic toxicity.

Study on the Typical Environmental Factors in the Middle Part of Zhoushan Fishery Based on HY-1C/D and Other Multi-Source Data

This study utilizes satellite data, including HY-1C/D, along with reanalysis data, to unveil the typical environmental characteristics of the sea surface in the middle of Zhoushan fishery. The article addresses three main issues. The first one is the development of an ocean primary productivity (OPP) inversion algorithm model. The second one is the study of chlorophyll-α (Chl-α) concentration and OPP distribution characteristics in Zhoushan fishery using China’s domestically produced ocean satellite HY-1C/D CZI data. The last one is the revelation of the characteristics of typical environmental factors on the sea surface at Zhoushan fishery by combining HY-1C/D with multi-source data. The results show the following: (1) The middle part of Zhoushan fishery exhibits significant seasonal and regional variations in Chl-α concentration and OPP. Chl-α concentration ranges mainly between 0.2 and 2.9 µg/L, with higher concentrations in spring and summer and lower Chl-α concentrations in autumn and winter. Spatially, Chl-α concentration gradually decreases from west to east. The OPP in the study area ranges from 100 mg·m−2d−1 to 1000 mg·m−2d−1, with high OPP values distributed on the western side, ranging from 400 mg·m−2d−1 to 1000 mg·m−2d−1, and gradually decreasing seaward. The highest OPP occurs in summer and the lowest in winter. (2) The correlation analysis between Chl-α concentration and OPP revealed a strong positive relationship. Consequently, this study developed an empirical model for estimating OPP based on Chl-α concentration and validated its feasibility. The model applies to areas with Chl-α concentrations ranging from 0.2 to 4 µg/L. (3) The convergence of freshwater injection, multiple ocean currents, and seasonal upwelling in the study area brings about a rich supply of nutrients. Additionally, the region is characterized by suitable conditions, including optimal Chl-α concentrations, OPP, SST, salinity, currents, and geological water depths. The synergistic effect of these factors together contributed to the formation of Zhoushan fishery.

Sensitivity of Daphnia spinulata Birabén, 1917 to glyphosate at different salinity levels.

Daphnia spinulata Birabén, 1917 is an endemic cladoceran species, frequent in the zooplankton communities of the shallow lakes of the Pampean region of Argentina. These lakes have varying salinity levels and, being located in agricultural areas, are frequently subject to pesticide pollution. This study aimed to determine the effects of the herbicide glyphosate (Panzer Gold®) in combination with different salinity levels on the biological parameters of D. spinulata and its recovery ability after a short exposure. Three types of assays were performed: an acute toxicity test, a chronic assessment to determine survival, growth and reproduction, and recovery assays under optimal salinity conditions (1g L-1). The LC50-48h of glyphosate was 7.5mg L-1 (CL 3.15 to 11.72). Longevity and the number of offspring and clutches were significantly reduced due to the combined exposure of glyphosate and increased salinity. The timing of the first offspring did not recover after glyphosate exposure. Our results reveal that D. spinulata is sensitive to the herbicide Panzer Gold® at concentrations well below those indicated in the safety data sheet of this commercial formulation, which causes stronger negative effects in conditions of higher salinity. Further research is needed to shed light on the sensitivity of this cladoceran to glyphosate and its variability under other interactive stress factors.