Preliminary study on the impact of mussel integration on qualitative changes of water in an aquaponic system

Abstract

Freshwater resource sustainability is a growing concern in modern agriculture. Aquaponic systems, which integrate fish farming and soilless plant cultivation, offer a promising solution by enabling nutrient recycling within a closed water loop. However, the accumulation of organic waste and suspended solids can challenge system stability and water quality. This study investigates the potential of the freshwater mussel Unio crassus as a biological filter to enhance organic waste removal and water purification in aquaponic systems. Two system configurations were tested: the Media Bed System and the Nutrient Film Technique (NFT) system, each receiving identical daily tilapia effluent dosing, and containing identical plant cohorts (lettuce and collard greens) and U. crassus mussels. Over 30 days, key water quality parameters—total suspended solids (TSS), dissolved oxygen (DO), pH, and ammonia (NH₃)—were monitored, alongside plant biomass development. Results indicated that while the media bed system achieved significantly lower TSS concentrations (14.2 ± 2.1 mg L-1), the NFT system maintained higher DO levels (5.8 ± 0.6 mg L-1) and supported greater plant growth. Localised zones of improved clarity were observed near mussel clusters; however, quantitative mussel-specific contributions were not measured. Within this scope, integrating U. crassus may offer ecological value while warranting controlled, quantitative verification. Moreover, this approach may contribute to species conservation through practical ex situ applications. The study highlights the potential of hybrid aquaponic systems utilising both design types and nature-based filtration for sustainable food production.