Pilot-Scale Evaluation of Coral Reef Media for pH Buffering and Nutrient Supply in Koi-Lettuce Aquaponics

초록

Nutrient deficiencies and pH fluctuations are among the major issues identified in most aquaponic studies. Studies have mainly used chemical fertilizers and pH adjusters to resolve these issues; however, a sustainable and environment friendly permanent solution is needed. In this novel pilot study, we incorporated coral carbonate media into a koi carp-lettuce aquaponic system-A (APA) to provide a continuous release of Ca2+, Mg2+, Fe, and P and to support accumulation in plant and fish biomass while maintaining neutral pH, in order to compare with the control aquaponic-B (APB). In APA, mean FCR, SGR, and PER were recorded as 1.57 kg feed & centerdot;kg fish-1, 0.58%& centerdot;day-1, and 1.77 kg feed & centerdot;kg fish-1 protein, respectively, in comparison with the control APB which showed mean FCR, SGR, and PER as 3.45 kg feed & centerdot;kg fish-1, 0.27%& centerdot;day-1, and 0.80 kg fish & centerdot;kg protein-1, respectively. Also, the mean plant mass obtained during this 28-day study was 5.28 and 4.40 kg with a fish weight gain of 0.51 and 0.22 kg for APA and APB, respectively. In this pilot-scale study (n = 2 independent systems per treatment), the observed plant and fish biomass in APA were 20.9% and 10.1% higher respectively than APB; these values show descriptive differences observed in this study. Nutrient analysis was found to show higher release and accumulation of key nutrients in APA. This study examined a low-chemical, sustainable approach for aquaponics by using reusable coral carbonate media to maintain neutral pH and to improve nutrient availability and productivity.

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