Water Salinity Levels Research Articles

Estimate Raw Water Salinity for the Tigris River for a Long Time Using a Mathematical Model

The measurement data of the raw water quality of Tigris River were statistically analyzed to measure the salinity value in relation to the selected raw water quality parameters. The analyzed data were collected from five water treatment plants (WTPs) assembled alongside of the Tigris River in Baghdad: Al-Karkh, Al-Karama, Al-Qadisiya, Al-Dora, and Al-Wihda for the period from 2015 to 2021. The selected parameters are total dissolved solid (TDS), electrical conductivity (EC), pH and temperature. The main objective of this research is to predicate a mathematical model using SPSS software to calculate the value of salinity along the river, in addition, the effect of electrical conductivity on the salinity value was estimated. Multiple linear regression (MLR) and artificial neural network (ANN) models were used to estimate the mathematical models for calculating water salinity value in Tigris River and to present the highest effective parameter that effect on water salinity. In general, the results showed an increase in the water salinity level downstream of the Tigris River towards the south of Baghdad and the EC is the most significant effect on water salinity, and MLR and ANN analyses present a good indication of the mathematical models with highest coefficient of correlation (R2) as (0.999 and 0.998), respectively. In addition, the regression equations proved good performance in predicting the salinity value with error percentage less than 10% for all WTPs.

SALINITY STRESS AS AN ABIOTIC FACTOR AT GERMINATION STAGE ON DRY BEAN (Phaseolus vulgaris L.) CULTIVARS

The study focused on germination parameters as the most critical stage of plant development in dry bean cultivars under different salt treatment. For two used cultivars (Akman-98, Karaman-2016) the data on germination percentage, mean germination time, seedling shoot length, seedling root length, seedling length and seedling vigor indexes were reached under the different salinity levels of irrigation water (0 mM, 25 mM, 50 mM, 100 mM, 150 mM, and 200 mM of NaCl) in Petri plates. The data indicates that these parameters could be used as screening the dry bean cultivars against salt stress levels. This study was carried out in a Completely Randomized Design (CRD) with a total of 12 treatments (6 salinity x 2 cultivars) for the germination and seedling data each comprising of three replicates. The results demonstrated that; i) From the overall observation of the germination characters, at 100 mM and over salt treatments showed decreasing in the germination percentage, the seedling length and the seedling vigor index in the mean of the cultivars, ii) Significantly decreasing in the seedling shoot length were observed in the mean of the cultivars at just after 25 mM and gradually at all salt concentrations, iii) Although the root length showed increasing in 25 and 50 mM treatments than the control plants, a sudden decrease occurred after 100 mM salt treatment in the mean of the cultivars and in each cultivars separately, iv) The mean germination time were sharply in increasing starting with 25 mM treatment in the mean of the cultivars, v) Except the seedling shoot length, in the mean of all the salt treatments between the cultivars did not show statistically differences in the calculated parameters, vi) Any correlation was found between the salt concentrations and the cultivars.

Assessment of plant mineral nutrition concentrations of tomato irrigated with brackish water and RO concentrate

Salinity-induced nutritional imbalances due to irrigation with brackish water could adversely affect crop production. This study evaluated the concentrations and distributions of 14 ions in roots, stems, leaves, and fruits of tomato irrigated with brackish water. The five saline treatments were tap-water of EC 0.6, brackish water of EC 2 and 3, and reverse osmosis (RO) concentrate of EC 4 and 6 dS/m. The higher concentrations of Na, Mg, Ca, K, and Cl in soil and irrigation water increased Na and Mg but decreased K and Ca concentrations in plant organs. The accumulations of micronutrients (Fe, Mn, Cu, B, and Al) except Zn in the whole plant decreased with increasing salinity levels. However, the amounts of Mn, Fe, B, and Al were positively correlated to yield at a significant level. The Principal Component Analysis (PCA) identified two PCs that explained more than 70% of variability for the whole plant, PC 1 included most ions of Na, K, Ca, P, N, Mn, Cu, Fe, B, and Al, while PC 2 included ions of Mg, Cl, S, and Zn. These results were in accord with the results of Pearson correlation analysis that tomato yield was significantly correlated to accumulations of Na, Ca, P, N, Mn, Fe, B, and Al in whole plants except K and Cu. To achieve an optimal comprehensive fruit nutrition, tomato can be irrigated up to an irrigation water salinity level of ≤2 dS/m.

Examining the Effects of Biochar in Spinach Cultivation with Increased Irrigation Water Salinity on Some Physical and Physiological Properties of the Plant

The inadequacy of fresh water resources in today's conditions has revealed the use of salty water as an alternative water source in agricultural irrigation but salinity, which is shown as the most important source of abiotic stress, increases osmotic stress and decreases the water intake of the plant, resulting in a physiological drought. For this reason, there is a need for applications to improve the decreasing efficiency in the use of salt water in irrigation through different practical and economic approaches. This study investigating the effects of biochar application into the soil against irrigation water salinity in spinach cultivation on some physical and physiological properties of the plant was carried out in five-liter pots in greenhouse conditions, in a completely randomized factorial experimental design with three replications, in three different irrigation water salinity levels with NaCl salt source [I0: tap water; 0.4 (control), I1: 2.5, I2: 5 dS m-1] and three different biochar dosage based on weight [B0: 0 (control), B1: 1.5, B2: 3%] conditions. As a result of the study, plant height, leaf number and area, shoot wet weight from physical properties and chlorophyll and leaf relative water contents from physiological properties decreased with increasing irrigation water salinity levels but the membrane damage decreased, while the physical and physiological properties of spinach increased with the increasing mixing ratio of biochar to the soil, excluding membrane damage. It was found that the use of biochar against irrigation water salinity can be recommended considering that mixing biochar to the soil against irrigation water salinity in spinach cultivation regulates the physical and physiological properties of the plant but to obtain more comprehensive information on this subject, evaluation of different irrigation water salinity and biochar ratios in terms of field studies has emerged as a recommendable result.

Water extracts of Spirulina platensis and Chlorella vulgaris enhance tomato (Solanum lycopersicum L) tolerance against saline water irrigation

The research aimed to examine the enhancement effect of Spirulina platensis (blue–green microalga or Cyanobacterium) and Chlorella vulgaris (green microalga) water extracts as biological stimulant in improving growth parameters, chlorophyll content, yield, and fruit quality of tomato plants under salinity stress. Tomato seeds (Solanum lycopersicum L of cv. Agyad) were soaked in three microalgae water extracts at a 10% concentration (Chlorella vulgaris, Spirulina platensis, and Chlorella: Spirulina at a ratio of 1:1). Chemical and biochemical analyses for the used materials and products were achieved. After germination, tomato transplants were irrigated with saline water at three levels of saline water (2, 4, and 7 dS/m) using sea salt. Successive grown tomato transplant at 7.0 dS/cm were infused in clayey soil. The grown plants were prayed by algal extract and irrigated by the same solution. Vegetative growth, yield, shelf life, and chlorophylls (a and b) were determined. It was found that the highest vegetative growth, yield, and chlorophyll content were measured in tomato transplants with the Spirulina: Chlorella mixture, followed by Spirulina platensis and Chlorella vulgaris water extracts, all of these measurements increased significantly in response to microalgae treatments. Experimental tomato fruits of Chlorella and mixture treatments can stay for 45 days at room temperature. Both algal extracts and their mixture enhanced the bioaccumulation of micronutrients (Fe, Zn, Mn, and Cu) compared with the control, while Chlorella extract surpassed Spirulina and mixture extracts. Concerning the used dried algae and their water extract, Spirulina platensis surpasses Chlorella vulgaris for protein and ash content.

Irrigation and crop management using multi-objective optimization – A case study

Irrigation and crop management practices play a crucial role in ecology and agrohydrology and can have significant environmental and socio-economic impacts. The important decision factors include soil moisture and water salinity, particularly in arid and semi-arid regions. In this study, the effects of these two factors on maize are quantitatively measured. To collect data, design of experiments is utilized at a greenhouse in a research center. The dataset consists of eighteen variables, including sixteen qualitative, quantitative, and morphological maize characteristics, as well as two decision variables, i.e., water depletion and salinity. This endeavor aims to promote the use of multi-objective decision-making techniques in the water management context to improve agricultural practices in regions facing water scarcity.To ensure appropriate data analysis, besides data visualization, multivariate and repeated measures analysis of variance are employed. Subsequently, a repeated measures model is used to fit statistical models and construct the corresponding responses. Furthermore, to determine the optimal levels of soil moisture and water salinity, which are often in conflict with each other, the problem is approached within a multi-objective framework. The weighted p-norm method is employed to incorporate management priorities in the decision-making process and facilitate tradeoffs between these two factors. Policy implications based on the findings are provided, offering valuable insights for improving irrigation and crop management practices. Detailed guidelines are provided on how to effectively analyze a problem, construct a model, and verify its assumptions.

CHERRY TOMATO CULTIVATION UNDER DIFFERENT LEVELS OF IRRIGATION WATER SALINITY AND ROOT MANAGEMENT SYSTEM

The use of saline water is a challenge of modern agriculture since the use of this type water reduces crop quality and yield. From this perspective, this study aimed to analyze the performance of cherry tomato under different levels of irrigation water salinity and partial root-zone irrigation. The experiment was conducted in a plant nursery at the Engineering and Agricultural Sciences Campus of the Federal University of Alagoas, in Rio Largo, Alagoas, Brazil. The experimental design was completely randomized, in a 4 x 2 factorial arrangement corresponding to four levels of irrigation water salinity (0.5 (control), 1.5, 2.5, and 3.5 dS m-¹) and two root management systems (with and without root system division), with five replications. The plants were evaluated for growth, dry mass accumulation, and yield. The irrigation water salinity of 3.5 dS m-1 intensely reduces the plant height, number of fruits, and shoot dry mass of cherry tomato. The shoot fresh mass of cherry tomato was reduced by with root system division. However, this treatment increased the plant height and the number of fruits per plant. Root system division in cherry tomato plants mitigates the deleterious effects of irrigation water salinity up to the electrical conductivity of 1.5 dS m-1, especially on the fruit mass per plant.

Water extracts of Spirulina platensis and Chlorella vulgaris enhance tomato (Solanum lycopersicum L.) tolerance against saline water irrigation

The research aimed to examine the enhancement effect of Spirulina platensis (blue-green microalga or Cyanobacterium) and Chlorella vulgaris (green microalga) water extracts as biological stimulant in improving growth parameters, chlorophyll content, yield, and fruit quality of tomato plants under salinity stress. Tomato seeds (Solanum lycopersicum L. of cv. Agyad) were soaked in three microalgae water extracts at a 10% concentration (Chlorella vulgaris, Spirulina platensis, and Chlorella:Spirulina at a ratio of 1:1). Chemical and biochemical analyses for the used materials and products were achieved. After germination, tomato transplants were irrigated with saline water at three levels of saline water (2, 4, and 7 dS/m) using sea salt. Successive grown tomato transplant at 7.0 dS/cm were infused in clayey soil. The grown plants were preyed by algal extract and irrigated by the same solution. Vegetative growth, yield, shelf life, and chlorophylls (a and b) were determined. It was found that the highest vegetative growth, yield, and chlorophyll content were measured in tomato transplants with the Spirulina:Chlorella mixture, followed by Spirulina platensis and Chlorella vulgaris water extracts; all of these measurements increased significantly in response to microalgae treatments. Experimental tomato fruits of Chlorella and mixture treatments can stay for 45 days at room temperature. Both algal extracts and their mixture enhanced the bioaccumulation of micronutrients (Fe, Zn, Mn, and Cu), compared with the control, while Chlorella extract surpassed Spirulina and mixture extracts. Concerning the used dried algae and their water extract, Spirulina platensis surpasses Chlorella vulgaris for protein and ash content.

Effects of exogenous selenium application for enhancing salinity stress tolerance in dry bean

Excess salinity is one of the most important abiotic stress that negatively affect plant growth and development. Like many other leguminous crops, dry bean (Phaseolus vulgaris L.), is classified as salt-sensitive plant. Researches related to the use of selenium to reduce salinity stress have been increasing in recent years. However, no study has been found in the world literature that shows the effects of this element on reducing salinity stress in dry bean. The main purpose of this study was to determine whether the negative effects of salinity stress on growth, yield, and organic compounds of dry bean could be reduced by foliar selenium applications. Three different foliar application dosages of selenium (0, 5 and 20 ppm) under four different irrigation water salinity levels (control-0.6, low-1.6, moderate-3.0 and high-4.8 dS/m) were tested in the study. It has been shown that the foliar application of selenium, which is suggested to be used to reduce salinity stress in many plants, did not show, in general, a statistically positive trend for almost all growth, yield, and quality parameters in dry bean. Compared to the control salinity treatment, it was revealed that the application of 20 ppm selenium did not affect the salinity threshold value at a significant level, but this application had a very low positive effect on the slope value, which expresses the decrease in yield after the threshold salinity. In general, it was concluded that foliar application of selenium under studied concentrations had a minor effect than expected in improving the tolerance of salinity stress in dry bean.

Differential effect of water salinity levels on gas exchange, chlorophyll fluorescence and antioxidant compounds in ex vitro date palm plants

In this study, the response to salt stress was evaluated in ex vitro acclimated date palm plants, regenerated from in vitro culture multiplication. The plants, eighteen-month-old, were irrigated with 0 (control), 150, 300 or 450 mM NaCl solutions (high to very high-water salinity). Photosynthesis parameters and antioxidant compounds were determined at the end of the experiment in leaves. At 150 mM NaCl, net CO2 assimilation rate and internal CO2 concentration were not impaired; while transpiration and stomatal conductance decreased by 60 and 70%, respectively. By increasing salt concentrations, all gas exchanges parameters were decreased. Measurement of chlorophyll fluorescence and P700 redox state showed that PSII and PSI machineries were significantly enhanced under 150 mM NaCl, conditions. With the 300 mM NaCl, the PSI parameters remained unchanged compared to control, while some of the PSII parameters, such as NPQ and Y (NPQ), were increased. At 450 mM NaCl, photosystems functionality was light intensity (PAR) dependent. Only at low PAR, a significant increase of some PSI and PSII parameters was observed. At the contrary, with high PAR, most of the energy conversion functions were significantly reduced, especially those related to PSI, indicating that PSI was more susceptible for damage by salinity than PSII. To overcome high salinity stress, ex vitro date palm plants mobilized a cascade of physio-biochemical pathways including the antioxidant activity and proline biosynthesis. Overall, the salinity of irrigation water, and up to 150 mM, improves the physiological performance of ex vitro date palm plants, which manage to tolerate very high levels of this stress.

The interaction effect of leaching requirements, salinity of irrigation water, levels of added sulfur and type of organic matter on soil salinity cultivated with maize plants (Zea mays L.)

An experiment was carried out using pots in the plastic house of the Agricultural Research Station / College of Agriculture / University of Basrah / Karma Ali site during the year 2022, to study the effect of adding mineral sulfur, organic matter, leaching requirements, and salinity of irrigation water on soil salinity planted with maize plants. By using two types of organic residuses (cow and alfalfa residuses) and with three levels of added mineral sulfur (0%, 0.8% and 1.6%) and three levels of leaching requirements (15, 25 and 35%) in excess of the field capacity and two levels of irrigation water salinity ( 4 and 8 dSm-1), where organic residues and mineral sulfur were added mixed with the surface layer of the study soil and incubated for 60 days before planting yellow corn (Zea mays L.) while maintaining soil moisture at field capacity. After the process of incubating the soil with mineral sulfur and organic matter in pots, yellow corn seeds were sown with crop service operations such as fertilization and irrigation operations carried out according to the above treatments. After 60 days of planting, the plants were mowed to estimate soil salinity. And the end of the experiment. The results of the study showed that the addition of organic residuses led to a decrease in the electrical conductivity of the soil at the end of the experiment from 6.11 dSm-1 to 3.05 and 3.17 dSm-1 for the alfalfa and cows respectively, and the decrease was more clear "in the alfalfa residuses , and the level of leaching requirements exceeded 35% in reducing the electrical conductivity of the soil compared to the other two levels, to reach 3.16 dSm-1, and the salinity of irrigation water 4 dSm-1 excelled in reducing the electrical conductivity of the studied soil to become 3.01 dSm-1, while the value of the electrical conductivity of the soil increased with the increase in the percentage of addition of mineral sulfur to reach 2.58, 4.35, and 3.94 dSm-1 for the levels of 0, 0.8, and 1.6%, respectively.

Cultivo fertirrigado de mini melancia submetida à níveis de salinidade e aplicação foliar de silício

ABSTRACT The application of silicon (Si) represents one of the alternatives that can be used to mitigate the deleterious effects caused by salinity on plants in fertigated cultivation. The objective was to evaluate the effect of different levels of water salinity, associated with the use of sodium silicate on the production parameters and nutrient levels in the leaf and stem of mini watermelon in a protected environment. To conduct the experiment, a randomized block design was adopted, in a 6 x 2 factorial scheme, with 4 repetitions, with six levels of irrigation water salinity (1.05; 2.12; 3.26; 4.41; 5.91 and 7.32 dS m-1) and two types of Si application: without Si and in foliar solution. The following parameters were evaluated: plant height, stem diameter, number of leaves, leaf and stem fresh and dry mass; biometric variables and total soluble solids content in the fruits; and nutrient contents in leaves and stem. The use of Si associated with fertigation with different salinity levels promoted a positive response for peel thickness, ºBrix, fresh and dry mass of leaves, and Si accumulation in leaves and stem. Salinity alone promoted an increase in pulp weight, ºBrix of the fruits and potassium content in the stem, besides increasing the manganese content and inhibiting the zinc content in the leaves. There was a significant interaction for the manganese content in the stem, with a positive response in the absence of foliar-applied Si and a negative response in the presence of foliar-applied Si under different levels of salinity.

Growth, Morphological, and Biochemical Responses of Four Native Species to Salinity Stress

Native plants are of great value in landscape maintenance. Despite their importance in the landscape, the salt tolerance of most native plants has received little attention. The present research was designed to assess morphological, physiological, and biochemical responses of four Utah-native plants [Arctostaphylos uva-ursi (kinnikinnick), Cercocarpus ledifolius (curl-leaf mountain mahogany), Cercocarpus montanus ‘Coy’ (alder-leaf mountain mahogany), and Shepherdia ×utahensis ‘Torrey’ (hybrid buffaloberry)] at different salinity levels. Each species was irrigated with a nutrient solution at an electrical conductivity (EC) of 1.2 dS·m−1 (control) or saline solutions at ECs of 5.0 or 10.0 dS·m−1 for 8 weeks. The experiment was a randomized complete block design with 10 replications. At 8 weeks after the initiation of the experiment, A. uva-ursi and C. montanus ‘Coy’ had slight foliar salt damage with an average visual score of 3.7 (0 = dead, 5 = excellent with no sign of foliar salt damage) when irrigated with saline solution at an EC of 5.0 dS·m−1 and were dead at an EC of 10.0 dS·m−1. Similarly, C. ledifolius had an average visual score of 3.2 when irrigated with saline solution at an EC of 10.0 dS·m−1. However, almost no foliar salt damage was observed on S. ×utahensis ‘Torrey’ during the experimental period. In addition, the shoot dry weight of all species was reduced with elevated salinity levels in the irrigation water. Salinity stress also reduced gas exchange rates of plants and affected their mineral content. Proline accumulated in the leaves of native plants but was species-dependent. In conclusion, S. ×utahensis ‘Torrey’ was tolerant to salinity stress followed by C. ledifolius; A. uva-ursi and C. montanus ‘Coy’ were sensitive to salinity stress.

High salinity in drinking water creating pathways towards chronic poverty: A case study of coastal communities in Tanzania.

Seawater intrusion is a growing pressure in coastal communities worldwide, putting millions of people at risk of excess salinity in drinking water. This study examines the impact of saline water on people's health and labor allocation as potential pathways towards chronic poverty. Using a transdisciplinary approach based on a coupled human-water system framework, we test these linkages combining field data on well water salinity levels and rich household survey data in coastal Tanzania. The results suggest that increased salinity levels lead to more time spent collecting drinking water and an increase in illnesses. Moreover, households in poorer villages with weaker public infrastructure have limited access to alternative sources of drinking water, making them more vulnerable to scarce potable water resources stemming from high salinity. To prevent chronic poverty, communities vulnerable to saline drinking water need better adaptation strategies as well as groundwater monitoring and management.

Salinity Stress Effects on the Growth Yield and Quality Performance of Two Sweet Potato Varieties

The yield response of several sweet potato varieties to salinity stress has been extensively studied in the scientific literature, but no research on the Koganesengan and Beniazuma varieties has been identified. The purpose of this study was to examine the effects of various irrigation salinity levels on the growth (vine and tuber lengths, stem and tuber diameters, and number of leaves, shoots, and tubers), yield (fresh, dry, tuber, and total yields, and water use efficiencies for vine, tuber, and total yields), and quality parameters (dry matter, ash, crude fiber, starch, phenolic matter, antioxidant activity, ß-carotene, ascorbic acid, protein, saccharose, glucose, and fructose contents) of these sweet potato varieties under drip irrigation. The findings show that without a varietal difference, increasing water salinity levels increased soil salinity and decreased soil pH values. Some growth and yield parameters of “Beniazuma” were negatively affected by the salinity level, but not those of “Koganesengan”. Irrigation salinity levels only had an effect on the crude fiber content and antioxidant activity of “Koganesengan” and the ash, starch, ß-carotene, and ascorbic acid contents of “Beniazuma”. Significant variations between varieties were only seen under the control treatment for all yield parameters (except dry vine yield) and water use efficiency values. According to the calculated salinity threshold and slope values, “Beniazuma” is more sensitive to salt stress than “Koganesengan”.

Pengembangan Sistem Monitoring Tingkat Salinitas Air Pada Tambak Rumput Laut Berbasis Website

The level of salinity in water quality is one of the determining factors in the success of seaweed aquaculture production. The purpose of this study was to develop a website-based monitoring system for the level of water salinity in seaweed ponds. Monitoring system development is carried out by designing and developing an integrated website. Measurement of water salinity in ponds uses a sensor with a microcontroller connected via the internet network so that monitoring can be carried out without the need to go to the pond location. This type of research is development (Research and Development) which refers to the waterfall model (Planning, Analysis, Design, Implementation, Maintenance). The results of the research show that website development as a monitoring system has been successfully developed. There are four pages that can be displayed on the website for monitoring seaweed pond water salinity, namely the login page, homepage, viewing data, and monitoring water salinity. This research is expected to provide an overview in monitoring water quality in increasing the productivity of seaweed cultivation.

Impacts of Saline Water Irrigation on Soil Respiration from Cotton Fields in the North China Plain

Saline water irrigation has been widely used for crop production where agriculture is short of freshwater. However, information about the response of soil respiration to saline water irrigation is limited. To identify the effect of saline water irrigation on soil respiration, the experiment based on long-term saline water irrigation cotton fields (since 2006) was conducted in the Heilonggang area in 2021. Five salinity levels in irrigation water were tested (3.4 [S1], 7.1 [S2], 10.6 [S3], 14.1 [S4], and 17.7 dS m−1 [S5]), and deep ground water (1.3 dS m−1) was used as the control (CK). After 15 years of saline water irrigation, we monitored soil physicochemical properties and soil respiration. In addition, we developed a structural equation model of the relationship between them. The results demonstrated that saline water irrigation significantly reduced soil water-stable aggregate content and porosity by 4.42–45.33% and 6.52–14.10%, respectively, and attenuated soil cellulase, α-glucosidase, and alkaline phosphatase activity. Soil respiration under saline water irrigation was significantly reduced by 5.28–33.08%. Moreover, saline water irrigation with salinity below 10.6 dS m−1 had no significant effect on cotton yield. Moreover, soil salinity (62%), water-stable aggregate content (46%), and soil porosity (25%) had significant effects on soil respiration, and soil porosity had a significant positive effect on soil alkaline phosphatase activity according to the structural equation model. Overall, saline irrigation with salinity below 10.6 dS m−1 can alleviate water shortages and reduce soil carbon emissions without affecting cotton yield in the study area.

Continuous electrocoagulation treatment system for partial desalination of tropical brackish peat water in Sarawak coastal peatlands

Sarawak coastal peatlands located on Borneo Island have vast availability of brackish peat water sources especially in some coastal rural areas. However, brackish peat water is currently underutilized as the source for water treatment plants due to excessive salinity levels. As such, this study aims to investigate the salinity reduction in brackish peat water sources for domestic consumption in Sarawak coastal peatlands by utilizing continuous electrocoagulation treatment with aluminium electrodes. Correspondingly, this study analyzes the effects of salinity percentage, electric current, and flow rate on salinity reduction with electrocoagulation treatment. This study has found that the treated salinity levels in brackish peat water with 30 % of salinity percentage meet the Malaysia Class I in National Water Quality Standard. The study has also identified both monolayer and multilayer adsorption that occurs in electrocoagulation treatment as the precursor to salinity reduction. In addition, the presence of in-situ aluminium hydroxide coagulants could adsorb some sodium chloride from brackish peat water with 70 % of salinity percentage at 2503 mg/g of maximum adsorption capacity and 2.65 min−1 of adsorption rate. This study has also found that electrocoagulation treatment could achieve 91.78 % of maximum salinity reduction efficiency at an optimum electric current of 5 A and flow rate of 1.2 L/min in brackish peat water with 30 % of salinity percentage. This treatment system costs only Ringgit Malaysia (RM) 0.29 or United States Dollars (USD) 0.06 per meter cubic of treated brackish peat water. Overall, this study demonstrates that continuous electrocoagulation treatment could partially desalinate brackish peat water with 30 % of salinity percentage in which the treated salinity levels could be utilized for domestic consumption in Sarawak coastal peatlands at reasonable cost.

Hypoxia and Anoxia Tolerance in Diploid and Triploid Eastern Oysters at High Temperature

Increasing reliance on the use of triploid oysters to support aquaculture production relies on their generally superior growth rate and meat quality over that of diploid oysters. Reports of elevated triploid mortality have generated questions about potential trade-offs between growth and tolerance to environmental stressors. These questions are particularly relevant as climate change, coastal activities, and river management impact water salinity, temperature, nutrients, pH, and oxygen levels within key estuarine oyster growing areas. In particular, the co-occurrence of warm water temperatures and low dissolved oxygen concentration (DO) events are increasingly reported in estuaries, with potentially lethal impacts on sessile, oyster resources. To investigate potential differences in DO tolerance, diploid and triploid market-sized or seed oysters were exposed to continuous normoxia (DO > 5.0 mg L–1), hypoxia (DO < 2.0 mg L–1), and anoxia (DO < 0.5 mg L–1) at 28°C and their mortalities were monitored. The hemolymph of the market-sized oysters was collected to measure cellular and biochemical changes in response to hypoxia and anoxia, whereas their valve movements were also measured. In general, about half of market-sized oysters died within about 1 wk under anoxia (LT50: 5.7–8.9 days) and within about 2 wk under hypoxia (LT50: 11.9–19.4 days) with diploid oysters tending to die faster than triploid oysters. Seed oysters took longer to die than market-sized oysters under both anoxia (LT50: 9.5–12.1 days) and hypoxia (LT50: 21.8–25.0 days) with diploid oysters (LT50: 9.5–11.8 days) dying slightly faster than triploid oysters (LT50: 11.8–12.1 days) under anoxia. Hemolymph pH decreased and plasma calcium and glutathione concentrations increased with decreasing DO, with values under anoxia being different than those under normoxia. Hemocyte density was also lower under anoxia than under either normoxia or hypoxia. Overall, few differences in physiological responses to hypoxia and anoxia were found between diploid and triploid oysters suggesting that ploidy (2N versus 3N) had limited effect on the tolerance and response of eastern oysters to low DO.

Effect of Different Water Salinities on the Larvae of the Blue Bream Ballerus ballerus (Linnaeus, 1758) during Rearing

The influence of water salinities of 3, 5, and 7 ppt on the growth and survival of Ballerus ballerus (L.) larvae was studied. The control group was fish reared in freshwater (0 ppt). The larvae showed high tolerance to water salinities of 5-7 ppt. The mean final weight of the larvae ranged from 48.6 to 64.1 mg, with corresponding mean total lengths from 18.9 to 22.6 mm, depending on the water salinity level. The best larval length increments were recorded in water with salinity of 3 ppt. They were only slightly lower in 0 ppt water, and there were no statistically significant differences between the breeding rates calculated for larvae reared in 3 ppt water. Depending on the salinity level of the water, the final survival rate of the blue bream larvae ranged from 83.5 to 98.6%. The blue bream larvae reared in water with salinity levels of 5 and 7 ppt were statistically smaller than the others, but the results obtained were equally satisfactory.