Herbaceous plants as part of biological filter for aquaponics system

Aquaponics is a recirculating aquaculture system (RAS), where plants and aquatic animals are grown using the same water. In these systems, plants act as part of biological filters. The cultivation of O. basilicum, Menta x piperita and M. spicata is commonly integrated to the production of O. niloticus in aquaponics. The aim of this study was to evaluate the ability of these herbs as part of biological filters for tilapia intensive production in aquaponics. Various physicochemical parameters were evaluated as water quality indicators. N and P content in the different elements of the system were also measured. Results showed that for tilapia growing the three herbaceous evaluated could be used as part of the biological filters in aquaponics, because they remove significant concentration in nitrogen compounds and phosphates; however, there were no differences among species. There was a positive relationship between the time and the levels of NH₄ and therefore NO₃^? in the water. The pH, temperature and dissolved oxygen were kept at appropriate ranges for tilapia. The electrical conductivity and total dissolved solids were in suitable levels for growing herbaceous, which adapted to flooded substrates, with water constantly moving and high concentration of dissolved oxygen. A key parameter to consider is the oxygen concentration in water when herbaceous is used in aquaponics, due to the high input of this element for these species need, especially basil. Tilapia largely incorporated N and P entering the system.     

Structural and biophysical properties of whole leaf and root tissue and isolated cell walls of common green bean and tomato seedlings grown in an aquaponics system relative to soil-grown counterparts

Due to increased demand for high-yielding agricultural methodologies – which are both sustainable and economically viable for the local market – research on new, alternative methods has become imperative. In this paper, crops grown within an aquaponics system are compared to soil-grown counterparts to observe the changes that occur in the key structural components and energy-producing components. The growth of the plants was monitored in both systems by consistently testing photosynthetic yield, chlorophyll content, the height of the plant, and the surface area of the leaves. After the growth period was completed, the plants were harvested and tested for changes in the fine structure of the plant. The water in the aquaponics system was monitored through the growing process and remained a stable environment for both the plants and the tilapia. The soil used to grow the traditionally grown counterparts was also tested for the same components as the water in the aquaponics system. The results from these procedures were indicative of increased growth rates, biomass production in stem and roots, incorporation of nitrogen, photosynthetic output, and cell respiration, as well as changes to the fine structure of the plant cell wall. It is the hope of this initial investigation to open up further detailed investigations concerning the effect on crops grown using aquaponic-based agriculture.

     

Exploring economic and legal barriers to commercial aquaponics in the EU through the lens of the UK and policy proposals to address them

Aquaponics is a food production system which connects recirculating aquaculture (fish) to hydroponics (plants) systems. Although aquaponics has the potential to improve soil conditions by reducing erosion and nutrient loss and has been shown to reduce food production related carbon emissions by up to 73%, few commercial aquaponics projects in the EU and UK have been successful. Key barriers to commercial success are insufficient initial investment, an uncertain and complex regulatory environment, and the lack of projects operating on a large scale able to demonstrate profitability. In this paper, we use the UK as a case study to discuss the legal and economic barriers to the success of commercial aquaponics in the EU. We also propose three policies: (1) making aquaponics eligible for the new system of Environmental Land Management grants; (2) making aquaponics eligible for organic certification; and (3) clarifying and streamlining the aquaponics licence application process. The UK’s departure from the EU presents a unique opportunity to review agricultural regulations and subsidies, which in turn could provide evidence that similar reforms are needed in the EU.

     

Productivity and economic viability of snakehead Channa striata culture using an aquaponics approach

This study was carried out to investigate the viability of utilizing aquaponic technology in culturing local fish: snakehead Channa striata and water spinach Ipomoea aquatica. Snakehead was raised for 150 days in a floating plastic pond with an area of 3 × 4 × 1.2 m having a capacity volume of ∼14.4 m³. Fish were randomly arranged into two experimental systems at density of ∼0.3 kg fingerlings/m³ e.g. SAQ – snakehead in aquaponics; SC – snakehead in normal system where control ponds were continuously aerated with ∼20% daily exchange of water. Fish were fed commercial feed twice a day. Initial results showed that in aquaponics compared with normal systems the SAQ efficiency exhibited 70% water exchange; five times lower in NH₃ level: (0.01–0.03 mg/L vs. 0.05–0.16 mg/L); three times lower in NO₂ level: (0.28–0.58 mg/L vs. 0.56–2.59 mg/L). Snakehead production was significantly higher in aquaponics with higher survival ratio of fish: 99.76% vs. 71.40%; ∼3 times higher in fish yield: 366 kg vs. 130 kg. The production of water spinach was also elevated in aquaponics versus normal systems 406.4 kg vs. 188 kg. The total income from snakehead and water spinach in SAQ were 4 times higher than in normal farming systems: 1219.42 $US and 307.04 $US. Based on the results of the current study, it is expected that applying aquaponics utilizing local available materials and species will enhance the sustainability of the overall system and keep the aquaponics lasting and expanding to social life especially on sustainable culturing snakehead Channa striata.     

Is aquaponics good for the environment?—evaluation of environmental impact through life cycle assessment studies on aquaponics systems

Aquaponics is often presented as a sustainable food production system that can reduce environmental costs of global food production; yet, its actual environmental effects are understudied. The aim of this research was to review the limited number of life cycle assessment studies dealing with aquaponics, and to highlight environmental cost and benefit of this practice. Our assessment highlights some of the problems, challenges, and advantages of aquaponics as a valuable food production system. We propose guidelines for future life cycle assessments of aquaponics that will facilitate policy and decision-making for farmers with respect to aquaponics.

     

Integrated production of fish (pacu <Emphasis Type="Italic">Piaractus mesopotamicus</Emphasis> and red tilapia <Emphasis Type="Italic">Oreochromis</Emphasis> sp.) with two varieties of garnish (scallion and parsley) in aquaponics system

Aquaponics is emerging as an alternative for high-health food production. Being able to identify the technical viability of non-conventional plants and fish species would help to increase the interest and possibilities in aquaponic systems. The goal of the present study was to evaluate the aquaponics production of two garnish species: scallion (S) and parsley (P), using effluents of pacu and red tilapia culture. Two aquaponics devices were used, differing according to the fish species, generating two different effluents. Thus, for plant performance, four treatments were evaluated in a factorial design (plant species and fish effluent as main factors), as followed: Pacu-S, Tilapia-S, Pacu-P, and Tilapia-P, with three replicates each, for 35 days. Fish performance was evaluated using Student’s t test. Each experimental device included a fish tank, filters, and six experimental units for the plants (floating rafts). Results indicated that feed conversion ratio (FCR) was higher in tilapia as compared to pacu (p < 0.05); however, fish productivity and survival were similar between species. Plant performance parameters were similar with no significant differences regardless of the fish effluent (p > 0.05), except for higher number of leaves per plant in scallion cultured using pacu effluent. Plant performance comparing both plant species indicated that scallion performed better as compared to parsley in all parameters. In addition, scallion also performed better related to the plant quality index. The results indicate that pacu presented a viable alternative for the aquaponics production, and regarding to the garnish, scallion performed better results as compared to parsley.     

Profitability of multi‐loop aquaponics: Year‐long production data,economic scenarios and a comprehensive model case

This case study examined the productivity and economic performance of a double recirculation aquaponic system in Germany with a total interior area of about 540 m². Calculations were carried out as an ex post analysis based on one‐year production data. The initial situation was not profitable; therefore, two scenarios were developed, which envisaged a significantly improved productivity of the fish as well as of the plant unit and a more than threefold enlargement of the greenhouse to make maximum use of the fish effluent. An ex ante analysis was performed and showed that the second scenario was profitable with a payback period of about 12 years. On the basis of this scenario, a simple but comprehensive model case with the complete set of economic key indicators showed that aquaponics is feasible if it exploits its potential, regardless of the high initial investment costs. The model case would cover an overall space of about 2,000 m², which is suitable for professional aquaponics in urban and peri‐urban areas with their limited space availability. Furthermore, multi‐loop aquaponics with its inherent circles fits into the circular city concept and implements resource‐efficient and sustainable food production into the urban fabric, which is important with increasing urbanization.     

Towards commercial aquaponics: a review of systems,designs, scales and nomenclature

Aquaponics is rapidly developing as the need for sustainable food production increases and freshwater and phosphorous reserves shrink. Starting from small-scale operations, aquaponics is at the brink of commercialization, attracting investment. Arising from integrated freshwater aquaculture, a variety of methods and system designs has developed that focus either on fish or plant production. Public interest in aquaponics has increased dramatically in recent years, in line with the trend towards more integrated value chains, greater productivity and less harmful environmental impact compared to other production systems. New business models are opening up, with new customers and markets, and with this expansion comes the potential for confusion, misunderstanding and deception. New stakeholders require guidelines and detail concerning the different system designs and their potentials. We provide a definitive definition of aquaponics, where the majority (>?50%) of nutrients sustaining the optimal plant growth derives from waste originating from feeding aquatic organisms, classify the available integrated aquaculture and aquaponics (open, domestic, demonstration, commercial) systems and designs, distinguish four different scales of production (≤?50, >?50–≤?100 m², >?100–≤?500 m², >?500 m²) and present a definite nomenclature for aquaponics and aquaponic farming allowing distinctions between the technologies that are in use. This enables authorities, customers, producers and all other stakeholders to distinguish between the various systems, to better understand their potentials and constraints and to set priorities for business and regulations in order to transition RAS or already integrated aquaculture into commercial aquaponic systems.     

Selection of suitable aquaponics system for empurau (Tor tambroides) fries nursery in polyculture method

Aquaculture International - Long-term use of the recirculated water for fish and crop production in the aquaponics system that is the major concern in sustainable aquaculture for reduction of the...     

Nitrogen transformations in aquaponic systems: A review

In recent years, aquaponic systems have gained significant popularity as soilless agriculture systems for organic fruits and vegetables production with concomitant remediation of aquaculture effluent. Aquaponics is a potential sustainable food production system that integrates aquaculture with hydroponics in which nitrogen-rich effluent from the fish production is utilized for plant growth. Because nitrogen is one of the most important inputs in an aquaponic system, it is critical to investigate the nitrogen transformations in the system for enhanced recovery of resources. Since studies on nitrogen transformations and nitrogen utilization efficiency (NUE) in aquaponic systems have been very limited, this review critically examines the important fates of nitrogen from input to outputs (e.g., ammonia nitrogen generation, nitrification, nitrate assimilation and nitrogen loss) to improve NUE in aquaponic systems. Various factors affecting the nitrogen transformations are also discussed. Furthermore, an example of nitrogen imbalance between nitrate uptake and nitrate generation rates in an aquaponic system was demonstrated. This review aims to advance our current understanding of nitrogen transformations and outlines future research needs in aquaponic systems, a sustainable model for efficient water and nutrient managements, and food production.     

An Investigation of Aquaponics Using Brackish Water Resources in the Negev Desert

An aquaponics system using the brackish waters of the Negev (conductivity approximately 4500 μS/cm) is described. Tilapia sp. were grown with a variety of vegetables, herbs, and other plants within three systems within an aquaculture hothouse: a brackish water floating raft system, a brackish water gravel system, and a fresh water floating raft system. Water quality remained adequate within all systems for plant growth and fish health. Growth rates for fish were low, averaging about 1.4 g/day. Standing stock of fish at harvest was 12.5 kg/m³. Plants required the addition of iron chelate to contend with chlorosis and some macro- and micronutrients seem to have been in short supply.     

Economic analysis of aquaponics and hydroponics production in the U.S. Midwest

This article examined the profitability of aquaponics in the U.S. Midwest. Three sources of data were considered for the study: (1) three active aquaponics farms, (2) a university greenhouse experiment, and (3) published research. The first analysis compares the economics of aquaponics and hydroponics systems under similar operations. Results suggest that the aquaponics system requires higher investment and operating cost but has lower production of vegetables compared with the hydroponics system. However, if aquaponics vegetable production is managed as an organic production, and the produce is sold at 20% premium price, aquaponics becomes profitable. The second analysis constructed three different representative farm sizes of aquaponics production of basil and tilapia—small, medium, and large. The production of basil provides better economic returns than the fish. All farm sizes are feasible when the basil price is above $10.00 per kg. The larger farm has the best results because of lower cost of production.     

Aquaponics and sustainability: The comparison of two different aquaponic techniques using the Life Cycle Assessment (LCA)

Aquaponics is generally regarded as a sustainable practice, but its environmental burdens were not yet deeply investigated. In this study, Life Cycle Assessment (LCA) was used to assess the environmental impacts of two hypothetical coupled aquaponics systems (CAPS): Raft System (RAFT) and Media-Filled Beds System (MFBS). Rainbow trout (Oncorhynchus mykiss) and lettuce (Lactuca sativa) were considered as cultivated species in both systems. The Simapro^© software V.8.0 was used for calculation. The comparison between the two virtual systems indicated the floating technique as the less impacting one. Even though energy consumption appears to be higher in the floating system, LCA results were markedly influenced by the extensive use of inert materials in MFSB. In both systems, contribution analyses underlined that the main environmental impacts are related to infrastructures, electricity and fish feed. The LCA analyses carried out in this study highlights that the choice of less impacting materials, and the optimization of management practices, should be taken as priorities in order to reduce environmental impacts of this activity.     

Tilapia recirculating aquaculture systems as a source of plant growth promoting bacteria

A recirculating aquaculture system with farmed tilapia is the most popular combination in aquaponics, an integration of aquaculture and hydroponics. Despite nutrient‐rich fish‐rearing water being regarded as a valuable resource for aquaponics, the quality and value of inhabitant microorganisms are certainly understudied. Our present research illustrates the feasibility of the tilapia‐rearing water as a valuable source of beneficial microorganisms called plant growth promoting bacteria (PGPB). Microbial communities were examined with a combination of culture‐independent high‐throughput 16S rRNA gene sequencing and cultivation methods. Microbial communities determined using high‐throughput sequencing indicated the usefulness of Bacteroidetes and Alphaproteobacteria as beneficial microbial indicators to assess the health condition of recirculating aquaculture systems. Siderophore production, ammonia production and phosphate solubilization assays were used for screening and 41% of isolates were identified as plant growth promoting bacteria. These bacteria were classified as Actinobacteria (eight strains [32% in total], Dietzia, Gordonia, Microbacterium, Mycobacterium and Rhodococcus), Bacilli (six strains [24%], Bacillus and Paenibacillus), Flavobacteriia (one strain [4%], Myroides), Betaproteobacteria (two strains [8%], Acidovorax and Chromobacterium) and Gammaproteobacteria (eight strains [32%], Aeromonas, Plesiomonas and Pseudomonas). We found that the tilapia‐rearing water naturally contained various lineages of PGPB and could be esteemed as a worthy seed bank of PGPB. Because aquaponics is a difficult system to use pesticides and herbicides, the role of PGPB to prevent plant pathogens and maintain healthy root system may be more important than traditional agricultural settings.     

Suitability and optimization of FAO’s small-scale aquaponics systems for joint production of lettuce (Lactuca sativa) and fish (Carassius auratus)

Aquaponics is a developing technique that combines the simultaneous production of plants (hydroponics) and fish (aquaculture). With it, the use of resources (i.e., water, nutrients, land) is reduced whilst at the same time minimising residues’ discharge to the environment. Among its benefits, it allows the production of healthy vegetables and fish in reduced spaces by means of small-scale systems. In this work, three of them based on FAO models with different hydroponic subsystems (nutrient film technique -NFT-, floating raft, and vertical felt) are tested to produce lettuce (Lactuca sativa) and goldfish (Carassius auratus). Water parameters as well as the growth of plants and fishes were monitored in two different production cycles. The hydroponic subsystem that outperformed the best was the NFT, both in terms of crop production and water consumption. All systems showed similar results in fish production. Further research is needed to corroborate the outputs obtained when using other combinations of plants and fishes. Small-scale aquaponic systems are particularly interesting for self-production and even more so in urban environments with reduced available space.     

Characterisation of aquaponic producers and small-scale facilities in Spain and Latin America

Aquaponics is a sustainable food production system combining hydroponics and aquaculture. Although the domestic/small-scale aquaponic production has proliferated worldwide, there is scarce knowledge about how it is performed. The objective of this study was to determine the profile and motivations of aquaponic producers, the characteristics of the facilities and the performance of the production. The average aquaponic producer is a middle-aged man, with a certain level of studies and a moderate household income. The main motivations reported were the production of high-quality, healthy food, the concern for the environment and the autonomy gained. These motivations conditioned the purposes of the aquaponic facilities (mainly education, production of food for self-consumption and as a hobby), which, excepting small sales, did not have an economic motive. Due to their characteristics, aquaponic facilities are particularly adapted for urban agriculture (many of them were located on rooftops) and most of those studied were constructed recently. The nutrient film technique was the most used hydroponic subsystem, followed by media beds, where mostly a polyculture of leaf and fruit vegetables and aromatics are produced. Tilapia was the most common fish species used. In general, there is a lack of proper knowledge and expertise about these complex systems in order to efficiently operate them.

     

Effect of plant density in coupled aquaponics on the welfare status of African catfish,Clarias gariepinus

We investigated the effects of plant density on the welfare of African catfish, Clarias gariepinus, in coupled aquaponics over 85 days. The moderate density (mpd) of basil, Ocimum basilicum, was compared with the high density (hpd) and control (n = 0). The behavior was analyzed by visual and video observations, and after the application of induced stressors, skin injuries, blood glucose, lactate, and plasma cortisol responses were considered. The hpd fish showed the least activity (control: visual 77.8%, video 81.6%; mpd: 74.6%, 82.6%; hpd: 63.2% [p < 0.05], 78.8%). High agonistic behavior (control: 5, 131; mpd: 4, 57; hpd: 1, 45) and the highest number of injuries (control: 3.9; mpd: 2.9; hpd: 3.4) were observed in the control. Glucose and lactate levels did not differ significantly (control: 5.5, 2.6 mmol/L; mpd: 5.6, 2.7 mmol/L; hpd: 5.3, 2.6 mmol/L); however, cortisol levels did (control: 18.8 ng/mL, mpd: 19.9 ng/mL, hpd: 25.8 ng/mL). pH adjustment led to additional stress, resulting in temporal cortisol alterations. While in the control and mpd, low cortisol levels were followed by acute responses and downregulation, the hpd fish showed prior elevation and lagged an acute response. However, comparing injuries and behavioral patterns with control, aquaponics with high basil density influenced African catfish positively.     

Effect of support medium,hydraulic loading rate and plant density on water quality and growth of halophytes in marine aquaponic systems

The development of marine intensive land‐based aquaculture systems has been limited due to the absence of methods to manage saline wastewater. Aquaponic systems, although commonly applied to freshwater aquaculture, can potentially manage nutrient wastes while providing a secondary product. The aim of this study was to evaluate both the capacity for water treatment and the production requirements of two saltwater‐tolerant plant species (Sesuvium portulacastrum and Batis maritima) when grown hydroponically in a marine aquaponic system. The presence of plants was found to significantly contribute to nitrate removal, such that mean nitrate concentrations were 10.1 ± 5.4 and 12.1 ± 6.1 mg/L NO₃^?‐N in planted and unplanted treatments respectively. The use of coconut fibre as a planting medium also significantly contributed to nitrate removal, such that mean nitrate concentrations were 9.78 ± 5.4 and 12.4 ± 6.0 mg/L NO₃^?‐N in coconut fibre and expanded clay treatments respectively. Daily nitrogen removal was greatest in the coconut fibre/plants treatment, ranging from ?18% to 67%. Hydraulic loading rate, plant species and plant density did not significantly affect water quality or plant growth. The low flow/saltwort/low density treatment had the greatest mean daily nitrogen removal, ranging from 25% to 172%. The results indicate that the main nitrogen removal mechanisms were simultaneous nitrification–denitrification in the hydroponic plant beds and nitrogen removal through plant growth. This study demonstrates that marine aquaponics could be an effective way to manage nutrient removal in marine land‐based aquaculture systems.     

Investigation in Reuse of Decommissioned Wastewater Facility and Reclaimed Water for Culturing Paddlefish Fingerlings

Reclaimed water is treated wastewater that has received at least secondary treatment and basic disinfection and is reused for beneficial purposes. The goal of this study was to develop a safe and reliable sustainable aquaculture system for producing stocker fish using reclaimed water in decommissioned wastewater treatment plants (WWTP) in Kentucky. The specific objectives were (1) to monitor paddlefish, Polyodon spathula, growth and survival and water quality in experimental tanks with static or flow‐through reclaimed water, (2) to evaluate the use of decommissioned tanks for large‐scale production of phase II paddlefish, and (3) to biomonitor paddlefish grown in reclaimed water for contaminants. Phase I paddlefish (11 ± 2.6 g) were produced by feeding live Daphnia collected daily from the clarifier tanks with hand‐pulled nets for 27 d. Phase II paddlefish were produced in four replicated 5600‐L experimental tanks with static and flow‐through reclaimed water. Paddlefish from the flow‐through system were significantly larger (199.2 ± 61 g) and had better feed conversion ratios (2.8 ± 2.1) than those from the static system (135.5 ± 51 g; 4.1 ± 1.6). For the large‐scale trial, two 1125 m³ decommissioned digester tanks were stocked with 50,000 paddlefish larvae per tank. One tank was treated as a flow‐through system with reclaimed water flowing at a rate of 280 L/min, while the other tank was treated as a static system where water was just added to replace that lost by evaporation. Survival rate (40%) and weight (194.1 ± 25.4 g) from the flow‐through system were significantly different from those of the static system (31%; 147.1 ± 6.5 g). This difference could be linked to better water quality in the flow‐through systems. Analyses for 38 contaminants were conducted on Daphnia, prepared diets, and paddlefish. All the concentration levels detected were at levels well below the FDA action limits and their permissible limits in edible food. The result from this project showed that paddlefish can be successfully produced in large-scale as stocker fish using reclaimed water in decommissioned tanks at WWTP.     

Food Production and Water Conservation in a Recirculating Aquaponic System in Saudi Arabia at Different Ratios of Fish Feed to Plants

An indoor aquaponic system (i.e., the integration of fish culture with hydroponic plant production in a recirculating setup) was operated for maximizing water reuse and year-round intensive food production (Nile tilapia, Oreochromis niloticus , and leaf lettuce) at different fish feed to plants ratios. The system consisted of a fish culture component, solid removal component, and hydroponic component comprising six long channels with floating styrofoam rafts for holding plants. Fish culture effluents flowed by gravity from the fish culture component to the solid removal component and then to the hydroponic component. Effluents were collected in a sump from which a 1-horsepower in-line pump recirculated the water back to the fish culture tanks at a rate of about 250 L/min. The hydroponic component performed as biofilter and effectively managed the water quality. Fish production was staggered to harvest one of the four fish tanks at regular intervals when fish attained a minimum weight of 250 g. Out of the total eight harvests in 13 mo, net fish production per harvest averaged 33.5 kg/m³ of water with an overall water consumption of 320 L/kg of fish produced along with the production of leaf lettuce at 42 heads/m² of hydroponic surface area. Only 1.4% of the total system water was added daily to compensate the evaporation and transpiration losses. A ratio of 56 g fish feed/m² of hydroponic surface effectively controlled nutrient buildup in the effluents. However, plant density could be decreased from 42 to 25–30 plants/m² to produce a better quality lettuce.