Aquaculture America 2024

February 18 - 21, 2024

San Antonio, Texas

ILLUMINATION AND SYSTEM DECOUPLING: THE IMPACT ON NUTRIENT DYNAMICS AND PRODUCT YIELD IN AQUAPONICS

Shima Rezaei*, Brendan Higgins, David Cline

 

Department of Biosystems Engineering

Auburn University

Auburn, AL 36830

szr0101@auburn.edu

 



 Over 23 million American households reside in food deserts, predominantly affecting marginalized communities in urban areas. Aquaponics holds promise as a sustainable solution, empowering local residents to cultivate fresh fish and vegetables. However, limited technical knowledge, system in stability, and  poor  product quality pose barriers for novice users. This study explores how design choices influence system stability, user-friendliness, and product quality. We conducted a two-factorial experiment examining the impact of algal biofloc and system decoupling. Expert researchers managed three replicates, while novice users in four Alabama high schools operate four additional replicates,  evaluating  aquaponics’ performance in novice user’s hands.

 Nitrification is crucial for aquaponic system stability and product quality. Improving nitrifying bacteria performance potentially enhances system reliability. In our study, most systems maintained stable nitrification with minimal ammonia levels. However, when fish were introduced, decoupled systems experienced a brief ammonia spike due to increased organic load and insufficient nitrifier abundance. In contrast, coupled systems benefited from the higher organic load, boosting nitrification and nitrate levels, while decoupled systems saw a decrease in nitrate levels due to the dilution effect.

 Algae-coupled systems outperformed bacteria-coupled systems in terms of achieving the highest fish growth, confirmin g the findings of prior research that even a small amount of algae in fish diets can enhance both fish growth and nutritional value. Furthermore, despite lower nitrate levels in algae-coupled systems compared to bacteria-only coupled systems, they obtained superior tomato biomass production. This may suggest that in algae- coupled systems, plants were able to absorb nitrate efficiently even though  a lower amount of nitrate was available.