World Aquaculture Magazine -December 2021

46 DECEMBER 2021 • WORLD AQUACULTURE • WWW.WA S .ORG 2019), although implications for Eh, pH and EC have yet to be explored. Filtration media composition or processes could further reduce oxidative stress and suppress pathogens and parasites (Cheng et al. 2010, Yakar et al. 2018). Applications of plant fertilizers are routine in aquaponics facilities due to the low availability of specific plant-required nutrients in the fish feed (either because it is colloidally bound or lacking completely) or the source water (Rakocy et al. 1982, 2010, Goddek et al. 2019, Lobanov et al. 2021). The chemical form of the added minerals plays a significant role in their bioavailability. Although well-documented in soil systems (da Cruz Ferreira et al. 2020, Imran et al. 2020, Naveed et al. 2020, Sharma and Mathur 2020), research on the interplay between mineral nutrients and plant oxidative stress response in aquaponic systems is lacking. This knowledge can better inform fertilizer and media application to minimize oxidative stress. Oxidative stress of aquatic animals extends beyond their physicochemical milieu, including nutritional components of feed (Olsvik et al. 2011, Gao et al. 2014, Dossou et al. 2018, Elia et al. 2018). Although largely impacting the organism through the gastrointestinal microbiota (Dawood et al. 2018), the ramifications of this stressor are widely recognized yet poorly understood. As such, tailoring feed composition to provide greater anti-oxidative capacity or mitigate oxidative stressors is a valuable topic for aquaponics, with extensive work underway on potential pre- and probiotic formulations indicating promising effects (Wang and Xu 2006, Wang 2007, Martínez Cruz et al. 2012, Toledo et al. 2019, Wang et al. 2019). Conclusion Observing and managing the interplay between Eh, pH and EC can provide valuable insights to farmers that can lead to improved system functionality, reduced crop loss, and improved product quality. Better monitoring devices and infrastructure to automate measurements and associated data analysis have spurred the integration of fundamental physical parameters into aquatic animal and plant farming. Until costs and knowledge obstacles are reduced however, a theoretical approach to managing Eh, pH and EC may be more practical. For instance, farmers may benefit from accruing data on the interplay between these fundamental parameters without needing a deeper understanding of their relationships, simply by following standardized protocols to correct the cultivation environment should it deviate from target ranges. Likewise, the farming community can benefit frommanagement strategies that prioritize buffering practices capable of regulating Eh, pH and EC within target ranges. These practices may range from specific farming strategies (regenerative/natural farming), regulation of other inputs including fish feed composition, fertilizer type and source, and health-promoting interventions (e.g., prebiotics, probiotics). More conscientious farming practices integrating Eh, pH and EC measurements should ultimately prioritize resisting oxidative stress in target organisms without tipping the scales in the opposite direction towards an environment that is overly reduced. While still in its infancy, inexpensive, non-invasive farmmanagement practices have the potential to streamline cultivation systems and shift the priority from disease treatment to disease prevention. Notes George J. Pate, Regenerative Aquaculture, 43 Needmore St., Walton, KY 41094 Joe@regenaquaculture.com Victor Lobanov and Alyssa Joyce, Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden * Corresponding author The author(s) would like to thank John Kempf and Olivier Husson for introducing the relationship among Eh, pH, EC and biological systems to the greater community through their free educational courses. The authors declare no conflicts of interest. The authors received no financial support for the research, authorship and/or publication of this article. References Abbasi, H., V. Vasileva, V. and X. Lu. 2017. The influence of the ratio of nitrate to ammonium nitrogen on nitrogen removal in the economical growth of vegetation in hybrid constructed wetlands. Environments 4:24. https://doi.org/10.3390/environments4010024 Ahnen, M., S.L. Aalto, S. Suurnäkki, M. Tiirola and P.B. Pedersen. 2019. 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