Browsing by Author "Guwa, Oyama"

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    Optimisation of nutrient input to integrated aquaponics systems through mineral supplementation by way of fish feed additives
    (Stellenbosch : Stellenbosch University, 2020-12) Guwa, Oyama; Goosen, N. J.; Salie, Khalid; Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering.
    ENGLISH ABSTRACT: Aquaponics is an integrated production system with the primary goal of sustainable food production in the form of fish and vegetables. The main challenge in aquaponics is the imbalance of nutrients between the fish and plants grown in the system as each has different nutritional requirements. The requirements of fish are met through fish feed and those of plants by supplementing nutrients, especially trace elements, through nutrient solutions, which adds extra costs to the production system. Therefore, the aim of this study is to design a feed to fulfil a dual role: provide optimal nutrition to the fish and optimise plant production in integrated aquaponics systems. The aims were met by i) determining whether dietarysupplementation of minerals through different feed additives in a recirculating aquaculturesystem can benefit the production performance and haematological profile of the Africancatfish, ii) determining whether dietary supplementation of minerals through different feedadditives in a recirculating aquaculture system can enhance the excretion of iron in wastewater for ultimate use in aquaponics systems, and ultimately iii) evaluating theperformance of the feed additives using the African catfish in combination with lettuce in anintegrated aquaponics system. The inclusion of feed additives, potassium, and iron in the diet of the African catfish improvedits haematological profile and excreted wastewater with high concentrations of potassiumand iron in a recirculating aquaculture system. Fish production and non-specific immunitywere not affected by the inclusion of different additives. Further investigations into anintegrated aquaponics system revealed that the inclusion of these feed additives at the rightinclusion level in the diet of the African catfish improved lettuce growth. The highconcentrations of potassium and iron excreted from the supplemented feed were absorbedby the lettuce in the aquaponics system, resulting in improved growth when compared to thecontrol treatment. From these results, it can be concluded that the addition of minerals through fish feed additives can reduce or even eliminate the need to supplement plants with nutrients in the form of nutrient solutions. The improvement of plant growth through dietary feed additives of fish in aquaponics systems can improve the efficiency of integrated aquaponics production systems. These results contribute to the improvement of the overall performance of the aquaponics system and the production of the African catfish in recirculating systems.