Introduction
Aquaponic systems, the combination of aquaculture (mainly recirculating aquaculture systems) and hydroponics (soilless plant production) as well as the corresponding research, are already present for more than 40 years (Naegel 1977, Watten and Busch 1984). As integrated agricultural systems they offer a huge potential with regard to the improvement of resource efficiency and circularity in agriculture. Nevertheless, this technology has not yet achieved widespread success and one important scientific approach, next to e.g. the systemic research on specific mechanisms, bottlenecks and technical optimizations, is to foster commercial success through the provision of reliable data on production efficiencies, product safety, best practices as well as the holistic comparison of different production systems using e.g. life cycle assessments (LCA´s).
Material & methods
A literature search was conducted to collect and evaluate the diverse field of aquaponics research of the last decades. Additionally, a consultation of different colleagues from various aquaponic research groups as well as different professional networks has been done to supplement these findings. And finally, also personal observations and findings are used to complete this overview aiming at presenting a bigger picture of this complex research area.
Results
Aquaponic systems offer diverse opportunities to overcome major bottlenecks of conventional production practices in aquaculture and horticulture such as the eutrophication potential or excessive water and resource use. Additionally, the use of aquaponic systems could also support the reduction of greenhouse gas emissions in controlled hydroponic production systems through savings of water and synthetic fertilizers without losses in productivity (Monsees et al. 2019). But here, the choice of system design itself plays also an important role (e.g. coupled or decoupled aquaponic systems, Fig 1).
Discussion
Despite the innovative and sustainable approach of aquaponics, further research is still needed to promote this promising technology. One important reason for the missing commercial success is probably the lack of standardized scientific experiments as well as meaningful data on the production costs, product values and investment returns (Colt et al. 2022). Difficulties with regard to the labeling of aquaponic products as organic (Fruscella et al. 2021) might be another obstacle, but only a minor one.
Here, the lack of applied data paired with the higher financial risks of building two production systems instead of one (and being able to professionally manage them together) and often complicated authorization procedures are still seen as the biggest barriers for economic success. Targeted subsidies as well as advanced education and research programs for these integrated agricultural systems might help to foster professionalization in aquaponics, to lower the risks for potential investors and to finally pave the way for the commercial success of these production systems.
References
Colt, J., Schuur, A. M., Weaver, D., & Semmens, K. (2022). Engineering Design of Aquaponics Systems. Reviews in Fisheries Science & Aquaculture, 30(1), 33–80. https://doi.org/10.1080/23308249.2021.1886240
Fruscella, L., Kotzen, B. and Milliken, S. (2021), Organic aquaponics in the European Union: towards sustainable farming practices in the framework of the new EU regulation. Rev. Aquacult., 13: 1661-1682. https://doi.org/10.1111/raq.12539
Monsees H, Suhl J, Paul M, Kloas W, Dannehl D, & Wuertz, S. (2019) Lettuce (Lactuca sativa, variety Salanova) production in decoupled aquaponic systems: Same yield and similar quality as in conventional hydroponic systems but drastically reduced greenhouse gas emissions by saving inorganic fertilizer. PLOS ONE 14(6): e0218368. https://doi.org/10.1371/journal.pone.0218368
Naegel, L. C. (1977) Combined production of fish and plants in recirculating water. Aquaculture, 10, 17-24. https://doi.org/ 10.1016/0044-8486(77)90029-1
Watten, B. J. & Busch, R. L. (1984) Tropical production of tilapia (Sarotherodon aurea) and tomatoes (Lycopersicon esculentum) in a small-scale recirculating water system. Aquaculture, 41, 271-283. https://doi.org/10.1016/0044-8486(84)90290-4