Aquaponics combines hydroponic crop production with recirculating aquaculture. These systems comprise various compartments ( in this case: fish tank, biofilter, sump, hydroponic floating raft, settler, and aerobic digester provided by Green in Blue ). Efficient d eveloping of aquaponics in terms of water quality, fish welfare, plant health and food safety requires a thorough understanding of the microbial composition for each compartment of the system . In this study 1 m3 dechlorinated tap water aquaponic system stocked with 50 Nile tilapia ( Oreochromis niloticus L., stocked at 5.7 kg per system) and 72 lettuce plants (Lactuca sativa Batavian Red) for 22 lettuce cycles of 5 weeks. The experiment was conducted in a small scale, closed-loop, simple recirculating aquaculture system (RAS) running for six months from 18 January ended on 21 July 2023. Several physico -chemical water parameters were monitored throughout the cycle to follow the general evolu tion of the system and correlate potential microbiota variations with water parameters and establish connection to the nitrogen cycle.
DNA sequencing results in Figure 1 clearly displays that aquaponics microbiome is complex and each compartment possesses its own bacterial community (p<0.05). An important genus in the biofilter is Nitrospira . This highlights its crucia l role in nitrification as no Nitrobacter or Nitrosomonas is detected in the biofilter. Nocardia. A substantial proportion of denitrifying Flavobacterium genus common in soil, aquatic systems and plant-associated habitats were detected in sump. Also, Cetobacterium genus related to fish gut.
As conclusion, metagenomics allows optimization of the operational parameters of the aquaponics system to prevent pathogen proliferation and pathogen cross- transfer among compartments, as well as to enhance efficient functioning of aquaponics biofilters.
Acknowledgement: Aquaponics from wastewater reclamation (AWARE). GA N. 101084245