Frugal Hybrid Aquaponic System: Design, implementation, and molecular validation under tropical climate conditions

Implementing aquaponics systems in developing countries requires low-cost, highly stable solutions. This study presents the design and validation of a Hybrid Aquaponic System (HAS) conceived to contribute to the food sovereignty of rural communities. A frugal technology approach was used, integrating a Multi-Criteria Decision-Making (MCDM) analysis with the Quality Function Deployment (QFD) methodology to prioritize low construction and operating costs under tropical climate conditions. Water quality (ammonia, nitrites, nitrates, dissolved oxygen) was monitored for 331 days. The modified Mann-Kendall and Kruskal-Wallis tests were applied to confirm system stability and identify significant differences among HAS units. Moreover, a biological characterization was performed using environmental DNA (eDNA) and a Principal Component Analysis (PCA), presented as a visual description of the physicochemical profiles linking nitrogen gradients to the structure of the identified bacterial communities, rather than as a generalization. The Shannon, Simpson, Chao1, and Spearman's correlation diversity indices were used to characterize a robust microbial community structure, identifying key taxa with potential relevance to the nitrification process. The results demonstrate a stably operating frugal HAS made viable through self-construction, thereby facilitating its accessibility and its potential to contribute to the food sovereignty of farming families.