The increasing global population has led to an increase in food demand; consequently, aquaculture is one of the food production sectors that has offered opportunities to alleviate hunger, malnutrition, and poverty. However, the development of a sustainable aquaculture industry has been hindered by the limited availability of natural resources as well as its negative impact on the surrounding environment. Hence, there is an urgent need to search for better aquacultural production systems that, despite their high productivity and profitability, utilize fewer resources such as water, energy, land, and capital in conjunction with a negligible impact on the environment. Biofloc technology (BFT) is one of the most exciting and promising sustainable aquaculture systems; it takes into account the intensive culture of aquatic species, zero water exchange, and improved water quality as a result of beneficial microbial biomass activity, which, at the same time, can be utilized as a nutritious aquaculture feed, thus lowering the costs of production. Furthermore, BFT permits the installation of integrated multi-trophic aquaculture (IMTA) systems in which the wastes of one organism are utilized as feed by another organism, without a detrimental effect on co-cultured species. This review, therefore, highlights the basics of BFT, factors associated with BFT for the successful production of aquatic species, the significance of this food production system for the sustainable production of economically important aquatic species, its economic aspects, drawbacks, limitations, and recommended management aspects for sustainable aquaculture.

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In the aquaculture feed industry, fishmeal is widely used as a source of animal protein due to its high palatability, excellent amino acid profile and increased digestibility.However, the incorporation of fishmeal in aquaculture diets increases the costs of production due to the declining wild fish stocks hence an urgent need to search for sustainable and cheaper alternative protein sources. The use of fermented plant proteins as substitutes for fishmeal in aquaculture diets has recently gained attention due to their improved nutritional quality, easy availability and low costs. Therefore, a systematic review and meta-analysis were conducted to quantify the effects of fermented plant proteins as substitutes for fishmeal on the growth performance, feed utilisation, survival, antioxidant, metabolic and digestive enzyme activity of several aquaculture species. Results of the meta-analysis indicated that replacement of fishmeal with fermented plant proteins in aquaculture diets enhanced the growth performance, feed utilisation, antioxidant and digestive enzyme activities of several aquaculture species regardless of experimental duration and source of fermented plant protein. Likewise, metabolic enzyme activity (i.e., Alanine aminotransferase and Aspartate aminotransferase) was reduced in experimental dietary treatment groups relative to the fishmeal control groups. To elucidate the influence of moderators on the observed effect sizes, a mixed-effects model was conducted and the results indicated that fishmeal substitution levels and aquaculture species influenced the observed effect sizes in both antioxidant and digestive enzyme activity. No significant differences were noted in survival between the experimental dietary treatment groups and fishmeal control diets among all aquaculture species. However, carnivorous marine species exhibited lower values for specific growth rate and protein efficiency ratio in experimental dietary treatment groups compared to the fishmeal control diets. Likewise, freshwater species exhibited poor FCR values in experimental dietary treatment groups relative to the fishmeal control diets. Overall, the replacement of fishmeal with fermented plant proteins in aquaculture diets is a safe and viable solution for increased and sustainable aquaculture production.

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The human population is expected to reach 9.7 billion by 2050. This in turn will put more pressure on the limited available resources such as land and freshwater. Combined with the high food demand, highly virulent pathogens, and worsening effects of climate change, cases of chronic hunger and malnutrition are expected to escalate in the future. Therefore, the implementation of sustainable food production systems is crucial in safeguarding food security. Recirculating aquaculture systems (RAS) have gained much attention today for the intensive production of certain aquatic species in controlled conditions. In these systems, wastewater is purified via several water purification steps and recycled back into the system. As such, water quality parameters such as water temperature, dissolved oxygen, dissolved carbon dioxide, pH, Total Ammonia-Nitrogen, nitrites, nitrates, and total soluble solutes are maintained within the desirable range required for proper growth and survival of the reared species. However, maintenance of good water quality largely depends on certain factors, most noticeably, the stocking density. Stocking densities below and above the recommended optimal levels negatively impact the behavior, growth performance, and immunity of reared animals. As a consequence, huge production losses are incurred. This review, therefore, aims to discuss the effect of stocking density on behavior, growth performance, feed utilization, and immunity of reared species in RAS. Moreover, optimum stocking densities of several aquatic species reared in RAS under certain culturing conditions are highlighted for sustainable production of food.

Salinity is one of the major abiotic stress factors that threaten crop development and sustainable food production. As a mitigation strategy, several plant growth regulators and osmoprotectants have been applied to ameliorate the negative effects of salinity stress in plants. Therefore, the current study aimed to investigate the effect of foliar applications of different concentrations of salicylic acid and proline on the growth, yield, fruit quality, and nutritional composition of cucumber crops grown under saline conditions. The three main irrigation salinity variations included electrical conductivity (EC) of 0.5 dS/m (control), EC 6.0 dS/m, and EC 12.0 dS/m. Foliar spray treatments were as follows: T1 (distilled water), T2 (1.0 mM salicylic acid), T3 (1.0 mM salicylic acid + 5.0 mM proline), and T4 (1.0 mM salicylic acid + 10 mM proline). Our results showed that foliar application of salicylic acid alone or in combination with proline under non-saline conditions improved the growth and yield of cucumber, with T4 recording the highest values. Irrigating plants with saline water (EC 6.0 and 12.0 dS/m) severely compromised cucumber's growth performance and yield, with the lowest values recorded at EC 12.0 dS/m. However, under EC 6.0 dS/m, T2 and T3 slightly ameliorated salinity stress effects regarding fruit yield, for T2, and nutritive composition of fruits, for T2 and T3. Overall, this study demonstrated that cucumber (Cucumis sativa L.) could tolerate irrigation salinity levels of up to EC 6.0 dS/m without significant detrimental effects on the growth performance, yield, and nutritional composition of fruits.

The environmental consequences of desalination concentrate disposal have limited the practical adoption of desalination systems for inland brackish water. Desalination concentrate, which is generated by desalination facilities, has the ability to offer water and nutrients for microalgal growth. A useful application for concentrate from desalination systems is required to boost the feasibility of installing desalination procedures for both inland brackish and seawater plants. Several research has been conducted to investigate the use of desalination concentrate as a medium for microalgal culture. This paper reviews the impact of desalination concentrate on microalgal productivity by describing instances of microalgae cultivated in desalination concentrate. Based on the research results, it was found that Chlorella vulgaris, Scendesmus quadricauda, S. platensis, Nannochloropsis oculata and Dunaliella tertiolecta can be cultivated on desalination brine. Also, the paper reviews the different applications of these types which may contribute to adding revenue that will reduce the cost of desalinated water.

Salinity and freshwater scarcity are significant challenges affecting agriculture production worldwide. Sustaining food production in arid and semi-arid regions requires innovative, efficient, and low-cost technologies. Integrated aqua-vegeculture systems (IAVS) are promising technologies for cultivating vegetable crops and rearing fish and in a closed-loop system. The system utilizes fish effluents as crop fertilizers and recycles water for increased productivity. Hence, the current study aimed to investigate the response and productivity of kale (Brassica oleracea L.) grown at different brackish water salinities in an IAVS. The greenhouse experiment followed a completely randomized design with three salinity variants (i.e., 3000, 6000, and 9000 ppm) and control (freshwater, 400 ppm) with four replicates per treatment. The study results indicated that kale grown in a greenhouse could tolerate salinity levels of up to 6000 ppm without significantly compromising the plants’ growth, yield, and nutritional composition of leaves. Likewise, rearing Oreochromis niloticus at high water salinities did not negatively impact the water quality and the growth performance, survival, and feed utilization of fish. Overall, cultivating kale and rearing O. niloticus in IAVS in water salinities reaching up to 6000 ppm could be a sustainable agricultural strategy to increase food production in regions affected by freshwater scarcity.