From land to water: circularity for the development of a zero-waste food supply chain

The rapid global expansion of aquaculture has driven the need for more sustainable and circular production systems capable of reducing environmental impacts and reliance on finite marine resources. This doctoral thesis aimed to contribute to the development of such systems by exploring innovative combinations of rearing technologies and alternative feed ingredients. The research encompassed seven studies, ranging from bibliometric analyses to applied trials involving several species (Solea senegalensis, Sparus aurata, Dicentrarchus labrax, Litopenaeus vannamei). In this regard, a global literature and text-mining analysis (Trial 1) revealed a marked increase in research addressing sustainable aquaculture, emphasizing alternative feeds and integrated farming systems. Then, experimental trials demonstrated that the inclusion of macroalgae (Ulva ohnoi) and probiotics (Phaeobacter sp.) in IMTA-RAS systems (Trials 2 and 3) improved growth, lipid profiles, and oxidative stability in Senegalese sole. Similarly, partial replacement of fishmeal with Hermetia illucens larvae meal in gilthead seabream diets (Trials 4 and 5) maintained product quality and extended shelf life, confirming the nutritional reliability of insect proteins. In biofloc systems instead, supplementing with specific microalgae species (Trial 6) enhanced shrimp growth and fatty acid composition, while aquaponic systems combined with spirulina- enriched insect meal diets (Trial 7) yielded high-quality European seabass with improved gut health. Overall, the thesis demonstrates that integrating sustainable feeds with resource- efficient aquaculture systems can produce nutritionally superior and environmentally responsible seafood. Thus, these results provide a scientific foundation for advancing circular aquaculture models that reconcile productivity, animal welfare, and ecological sustainability, contributing to the transformation of global food systems toward greater resilience and environmental compatibility.