The agricultural community has a challenge of increasing food production by more than 70% to meet demand from the global population increase by the mid-21st century. Sustainable food production involves the sustained availability of resources, such as water and energy, to agriculture. The key challenges to sustainable food production are population increase, increasing demands for food, climate change, and climate variability, decreasing per capita land and water resources. To discuss more details on (a) the challenges for sustainable food production and (b) mitigation options available, a special issue on “Water Management for Sustainable Food Production” was assembled. The special issue focused on issues such as irrigation using brackish water, virtual water trade, allocation of water resources, consequences of excess precipitation on crop yields, strategies to increase water productivity, rainwater harvesting, irrigation water management, deficit irrigation, and fertilization, environmental and socio-economic impacts, and irrigation water quality. Articles covered several water-related issues across the U.S., Asia, Middle-East, Africa, and Pakistan for sustainable food production. The articles in the special issue highlight the substantial impacts on agricultural production, water availability, and water quality in the face of increasing demands for food and energy.

Reclaimed water has been identified as a viable and cost-effective solution to water shortages impacting agricultural production. However, lack of consumer acceptance for foods irrigated with reclaimed and treated water remains one of the greatest hurdles for widespread farm-level adoption. Using survey data from 760 participants in the mid-Atlantic region of the U.S., this paper examines consumer preferences for six sources of reclaimed irrigation water and identifies statistically significant relationships between consumers’ demographic characteristics and their preferences for each type of reclaimed water. Key findings suggest that adult consumers prefer rain water to all other sources of reclaimed water. Women are less likely than men to prefer reclaimed irrigation water sources and are particularly concerned about the use of black and brackish water. Consumers who had heard about reclaimed water before are more likely to accept its use. Drawing on evidence from survey and experimental research, this paper also identifies disgust, neophobia and safety concerns as the key issues that lead consumers to accept or reject foods produced with reclaimed water. Finally, we identify avenues for future research into public acceptance of reclaimed water based on our analysis and evidence from prior research.

To investigate biomarkers representing the physiological and biochemical responses of the brackish-water clam Corbicula japonica, we conducted a full factorial-design experiment to test different water-temperature levels (20 °C and 25 °C), salinity levels (5 and 20 psu), and food-availability levels (0.5 and 2.0 mg suspended solids (SS)·ind⁻¹·d⁻¹). Increase in water temperature significantly decreased superoxide dismutase (SOD) and catalase (CAT) activities and oxyradical-absorbance capacity (ORAC), leading to lipid peroxidation (i.e., oxidative damage). Salinity activated or inhibited these biochemical markers. Food availability supported a detoxification mechanism against oxidative stress. Principal-components and cluster analyses revealed that a total of eight experimental conditions fell into three groups related to water temperature and/or salinity. The shift from Group I (20 °C water temperature) to Group II (25 °C water temperature and 5-psu salinity) demonstrated that the condition index, SOD, CAT, and ORAC had significantly decreased. With the further shift to Group III (25 °C water temperature and 20-psu salinity), we found a prominent increase in ORAC, which led to oxidative damage but no mortality. We conclude that future habitat changes driven by global warming should be closely watched, particularly given that local anthropogenic disturbances further add to natural ones.

This research investigates the application of Fertilizer Drawn Forward Osmosis FDFO technique and its potential use in Egypt under the Framework of the Water-Energy-Food Nexus. Fertilizers Drawn Forward Osmosis Desalination Technique has been proven to be a great exhibition of tackling one of the sustainability challenges from Water –Energy-Food Nexus perspective. Being an energy efficient technology, it offers a technical solution to provide alternative water supply without compromising energy consumption, moreover the product water quality is adequate for agriculture and crop production. In this work, feed solution used is real brackish groundwater extracted from a well in Sinai, Egypt. Two sets of experiments have been conducted in order to assess in selecting the proper scenario for the crop producer. The first set examined three commonly used single fertilizers in Egypt: Potassium Nitrate, Di-Ammonium Phosphate and Urea to compare between their performances. The second set examined standard hydroponic recipe, which is a mixture of nutrients, as a draw solution to fertilize crops in hydroponics systems. The nutrients mixture performance has been tested and compared to that of the individual components at the same concentrations in order to assess how mixing nutrients influence their performance. Regarding the first set, Di- Ammonium Phosphate resulted in the best performance as draw solute among the three tested draw solutes, where it has exhibited a significant water flux equivalent to 13.8 (Liter per membrane unit area per hour lm-2h-1 and always referred to as LMH, a feed ions rejection reaching 98% and acceptable concentrations of draw solute ions in the final product water. For the Second set, The Hydroponics nutrients mixture have exhibited better performance as draw solution compared to their individual macro-components. The use of the nutrient mixture as draw solute resulted in a flux of 11.7 LMH, 95% feed ions rejection compared to 9.2 LMH, 91%, and 10.03 LMH, 93% for its individual components. Mixing nutrients boosted the osmotic pressure and enhanced the driving force for fresh water permeation. Hence, it can be concluded that mixed nutrients have better performance than single fertilizers, not only for the enhanced desalination features and for water extraction performance, but also because they provide a complete set of nutrients necessary for growing crops.

An experiment were conducted to evaluate The effect of feeding frequencies and stocking size on growth and feed conversion ratio (FCR) of rainbow trout (O. mykiss) in brackish water for 102 days. Three stocking sizes (10, 25 and 40 g/fish) of rainbow trout and three feeding frequencies (feeding fish twice, three times and four times per day) were examined as the same time. Fish were fed at a restricted feeding program according to the rainbow trout standard table in the definite times during the light period. The results showed that in the group with 10 g initial weight increasing the feeding frequency, some growth factors like final weight, daily growth, and weight gain. But the other factors such as food conversion rate (FCR) and specific growth rate (SGR) decrease. It means in this group (10 g) two times feeding per day is not enough for an acceptable growth rate. In the two other groups with (initial weight 25 and 40 g) although by increasing the feeding frequency, some growth factors a little increase but these differences in 95% level (p≤0.05) are not significant. Therefore in rainbow trout culture with initial weight at least 25 g two times feeding per day was enough. The results of carcasses analysis of fish, showed that by increasing the feeding frequency there were no significantly difference at 95% level between the body compositions in all of treatments. With connivance of feeding frequencies, the best FCR was in the group with 10 g initial body weight and there was not any significant difference in SGR. So according to the results, it suggests that fish should be stocked with 10 g initial body weight. | Iranian Fisheries Science Research Institute | Published

A study was carried out to assess the culture performance of monosex and mixed-sex tilapia (Oreochromis niloticus) in underground brackish water by using semi-intensive integrated pond system. The experiment was conducted in three earthen ponds for a period of 11 months. In pond-1 (P1), 200 females and in pond-2 (P2), 200 males, while in pond-3 (P3), 100 male and 100 female tilapias were stocked. Salt-tolerant fresh biomass, i.e. Leptochloa fusca (Kallar grass), Brachiaria mutica (Para grass) and Kochia indica (Kochia) was used as supplemental feed. Fertilization of all ponds was done with goat droppings @ 6000 kg per ha and nitrophos @ 7.5 kg per ha. Results indicated that tilapia was found well adapted to the saline environment. The net fish production was calculated as 1295, 1752 and 914 kg per ha per year in female, male and mixed tilapia ponds, respectively. Male tilapia culture resulted in a significant (P less than 0.05) increase in fish production.

The growth response of juvenile round gobies was tested in various salinities to assess the potential performance of the species in widely differing salinities in the Baltic Sea and adjacent waters. An experimental approach analysed the survival, daily food intake and growth of juvenile Neogobius melanostomus from the brackish water region of the Kiel Canal, Germany. Round gobies (TL = 61.5 ±5.3 mm; n = 40) were fed ad libitum (diet = mysid shrimp; energy content = 4.7 cal per mg dry weight) at salinity levels of 0.1, 7.5, 15 and 30 over 12 weeks. Two replicate tanks (125 × 30 × 30 cm; 100 L) were maintained for each salinity level, each holding five specimens at a mean temperature of 19.90°C (±0.64°C; n = 136). Survival at all levels was 100%, except for 0.1 with 90%. Mean daily food intake (% of body weight) increased from salinity level 0.1 to 15 (from 17.76% to 19.95%); specimens at level 30 showed a more diversified and lower mean food intake (18.44%). Mean cumulative body weight gain appeared greatest at a level of 7.5 (224.52%), closely followed by 0.1 (206.57%) and 15 (191.92%). In contrast, fish growth was significantly lower at a salinity level of 30 (100.57%). Results of the experiment indicate that salinity tolerance estimates of the round goby made by other authors are too low regarding specimens that stem from brackish habitats. Growth patterns of some specimens, even in the salinity 30 treatment, show that a further spread of this species into regions with higher salinities is quite possible.

Riverine transport of dissolved inorganic carbon (DIC) from land to the ocean is an important carbon flux that influences the carbon budget at the watershed scale. However, the dynamics of DIC in an entire river network has remained unknown, especially in mountainous Japanese watersheds. We examined the effects of watershed land use and geology on the transports of inorganic carbon as well as weathered silica (Si) and calcium (Ca) in the Iwaki River system where agricultural and residential areas have developed in the middle and lower parts of the watershed. The concentration and stable carbon isotope ratios (δ¹³C) of DIC showed the longitudinal increase of ¹³C-depleted inorganic carbon along the river. As a result, most streams and rivers were supersaturated in dissolved CO₂ that will eventually be emitted to the atmosphere. The possible origin of ¹³C-depleted carbon is CO₂ derived from the decomposition of organic matter in agricultural and urban landscapes, as well as from in-stream respiration. In addition, agricultural and urban areas, respectively, exported the large amount of dissolved Si and Ca to the rivers, suggesting that CO₂ increased by respiration accelerates the chemical weathering of silicate and carbonate materials in soils, river sediments, and/or urban infrastructure. Furthermore, riverine bicarbonate flux is likely to enter shell carbonates of Corbicula japonica, an aragonitic bivalve, in the downstream brackish lake (Lake Jusan). These results revealed that the flux of DIC from the human-dominated watersheds is a key to understanding the carbon dynamics and food-web structure along the land-to-river-to-ocean continuum.