Integrated aquaponic food production systems are capable of producing more food on less land using less water than conventional food systems, and marine systems offer the potential of conserving freshwater resources. However, critical factors such as suitable species combinations, environmental conditions (salinity and pH), and nutrient management (animal to plant ratio, C/N ratio, and dietary crude protein) have not been fully understood for marine systems. There were four objectives in this project. The first objective was to evaluate the growth performance of potential comparable combination (whiteleg shrimp with three halophytic plants) for the development of marine aquaponics with BFT under different salinities. The second objective was to evaluate stocking densities and the C/N ratio on growth and production of whiteleg shrimp and three halophytes. The third objective was evaluation of varying concentrations of dietary crude protein in practical diets fed to shrimp raised in biofloc aquaponic saltwater systems. The fourth objective was to evaluate effects of pH levels and additional C on the growth and production of whiteleg shrimp and five plant species in marine aquaponics. Four conclusions were determined: 1) Regarding marine aquaponics, whiteleg shrimp and the three halophytes (Atriplex hortensis, Salsola komarovii, and Plantago coronopus) are suitable combinations for future development. According to the research results, shrimp performed better in a salinity of 15 and 20 ppt; yet, plants performed better in a salinity of 10 and 15 ppt. Therefore, a salinity of 15 ppt is suggested as the optimal saline condition for shrimp and the three halophytes in an indoor marine aquaponics system. In addition, inoculating probiotics do have the efficiency of stabilizing water quality, cultivating microbial community, and enhancing the health of shrimp and plants in the operation of aquaponics. 2) The stocking density ratio and C/N ratio exerted significant impacts on the performance of shrimp and plants in marine aquaponics. Shrimp performed better with the stocking density of 2:1 and 3:1, with no impact from the C/N ratio. Conversely, plants performed better with the stocking density of 3:1 and 5:1 with the C/N ratio at 15. Therefore, a stocking density ratio of 3:1 with a C/N ratio at 15 is suggested as the optimal condition for shrimp and the three halophytes in an indoor marine aquaponic food production system. Inoculating the water with biofloc and applying probiotics regularly can enhance the management of water quality and the health of shrimp and plants in aquaponics. 3) Among the findings of the study, shrimp growth was not affected by the protein content of the feed, suggesting that it is possible to use feeds with lower protein concentration when culturing shrimp in biofloc-based marine aquaponics. However, plants grew better in the treatments with higher protein content feed in the early and middle stages of production. Hence, for maximum production, providing a higher protein concentration feed (35 %) in the early stages of system start-up, and switching to a lower protein concentration feed (30 %) in the later stages of cultivation might be feasible. 4) The current study found no significant effects of pH or additional C on shrimp performance. In contrast, plants grew better in lower pH treatments, while additional C supplements improved the performance of plants grown in higher pH treatments and had similar results to the lower pH treatments. We suggest that RO water is not suitable source of water for shrimp-based marine aquaponics if ionic composition is not managed. The addition of C, however, led to improved growth and yields of most plants. Hence, adding C can be a promising approach in marine aquaponics to enhance the resistance to the abiotic stress of plants and improve their growth.<div> <br>The present study on marine aquaponics has produced important findings that will fill some knowledge gaps, provide management guidelines for production, and facilitate its development. <br></div>

This study explores the question of how soil-less agriculture through hydroponics, aeroponics, and aquaponics can empower smallholder farmers to achieve food sovereignty as portrayed in documentaries. It addresses the power imbalance between large corporations and smallholder farmers in the traditional agriculture industry. Documentary research approach is used to understand the various applications and research aspects of soil-less agriculture from around the world. Real-life examples from different countries where these methods have been successfully implemented in the agriculture industry, ranging from large industrial settings to smallholder farmers in disadvantaged communities, are analyzed. Further, content analysis is done on these documents by constructing a matrix that combines the process of empowerment and the six pillars of food sovereignty to analyze the different forms of empowerment. The study also investigates how the use of soil-less agriculture can build capabilities through enhanced “well-being freedom” and “agency freedom” and empower smallholder farmers to achieve food sovereignty.

Durch die Nutzung des fischfutterbedingten Nährstoffeintrags für die kombinierte Produktion von Fischen und Pflanzen können Aquaponiksysteme eine nachhaltige Erweiterung von Kreislaufanlagen der Aquakultur (RAS) darstellen. Herkömmliche Aquakulturfutter zielen jedoch auf Fischproduktion mit geringer Umweltbelastung ab und sind somit nicht für die Aquaponik optimiert. Daher weist RAS-Wasser häufig Mängel im Profil gelöster anorganischer Pflanzennährstoffe auf. So war es Ziel dieser Arbeit, die Auswirkungen unterschiedlicher Proteinquellen auf die Nährstoffdynamik in RAS durch Fütterungsversuche mit Afrikanischem Raubwels und Nil-Tilapia zu untersuchen, bei denen Wachstum, gelöste anorganische Nährstoffkonzentrationen im RAS-Wasser und die Ausscheidung von Nährstoffen über den Kot verfolgt wurden. Der Fokus lag auf nachhaltigen alternativen Proteinquellen zu marinem Fischmehl und terrestrischen Pflanzenproteinen: Larvenmehl der Schwarzen Soldatenfliege (BSFM), Welsschlachtabfallmehl (CM), Geflügelschlachtabfallmehl (PM) und Geflügelblutmehl (PBM). Experimentalfutter, die phosphorreiches PM und CM enthielten, förderten erhöhte Ausscheidung von löslichem reaktivem Phosphor, erzeugten die besten gelösten N:P-Verhältnisse im RAS-Wasser verglichen mit einer Hydroponik-Nährlösung und ermöglichten in Kombination mit PBM besseres Wachstum beim Wels als ein vergleichbares kommerzielles Futter. In Futtern basierend auf einer einzigen Proteinquelle führte PM bei Wels und insbesondere bei Tilapia zu ähnlichem Wachstum verglichen mit marinem Fischmehl, wohingegen BSFM und PBM bei beiden Arten Wachstumsleistung beeinträchtigte. Meta-Analysen aller Versuche legen nahe, dass höherer Phosphor-, Kalium- und Magnesiumgehalt im Futter erhöhte Ausscheidung dieser Elemente in gelöster Form bedingt, was sie zu Zielnährstoffen in Aquaponikfuttern macht, während die Optimierung des Protein zu Energie-Verhältnisses im Futter die gelösten N:P- und N:K-Verhältnisse im RAS-Wasser verbessern kann. / By using the nutrient input from fish feeds for the combined production of fish and plants, aquaponic systems can be a sustainable extension of recirculating aquaculture systems (RAS). However, conventional aquaculture feeds are optimized for fish production and reduced environmental impact rather than aquaponics. Hence, RAS water is often characterized by deficiencies regarding its dissolved inorganic plant nutrient profile. Therefore, this thesis aimed to explore the effect of purposeful dietary protein choice on nutrient dynamics in RAS through four systematic feeding trials involving African catfish and Nile tilapia in which growth performance, dissolved inorganic nutrient concentrations in RAS water and solid fecal nutrient excretion were tracked. Focus was on sustainable alternative protein sources to marine fish meal and terrestrial plant proteins: black soldier fly larvae meal (BSFM), catfish by-product meal (CM), poultry by-product meal (PM) and poultry blood meal (PBM). Experimental diets including phosphorus-rich PM and CM supported increased excretion of soluble reactive phosphorus, produced the most favorable dissolved N:P ratios in RAS water when compared to a renowned hydroponic nutrient solution, and, combined with PBM, enabled better growth performance in African catfish than a comparable commercial diet. In single protein source diets, PM produced similar growth performance in African catfish and particularly Nile tilapia versus marine fish meal, whereas BSFM and PBM impaired growth performance in both species. Meta-analyses covering all trials suggest that higher dietary phosphorus, potassium and magnesium content leads to their increased excretion in dissolved form, making them target nutrients for aquaponic feed formulation, while the optimization of the dietary protein to energy ratio can further improve dissolved N:P and N:K ratios in RAS water.