Innovative nutritional and ecological approaches for sustainable european seabass aquaculture

Global aquaculture is rapidly expanding but faces sustainability challenges, including limited fishmeal resources, disease outbreaks, and welfare concerns. High-value species like European seabass (Dicentrarchus labrax) require innovative strategies that balance growth, health, and environmental impact. This doctoral research addresses these challenges through three interconnected studies exploring nutritional, immunological, and ecological dimensions of sustainable seabass aquaculture. The first study investigated dietary nucleotides combined with vaccination. While nucleotides did not enhance growth, they improved hepatic and renal function, as indicated by reduced plasma ALT, AST, and LDH. Nucleotides modulated immune responses by upregulating IgM and lysozyme expression, balancing inflammatory (il-1β) and anti-inflammatory (il-10) genes. The nucleotide-supplemented vaccinated group exhibited enhanced antioxidant enzyme activity (SOD, CAT), skin mucus bactericidal activity against Vibrio harveyi, and reduced vaccine-related side effects, demonstrating synergistic immunomodulation. The second study evaluated integrating low-trophic species from Integrated Multi-Trophic Aquaculture—Sabella sp. and Ulva spp.—into seabass diets. These inclusions did not compromise growth, feed conversion, or survival. Hepatosomatic and viscerosomatic indices remained stable, while slightly reduced carcass lipid content suggested potential health benefits. Partial replacement of vegetable ingredients and krill meal supports circular economy principles without impairing production performance. The third study assessed invasive species (Anadara kagoshimensis and Callinectes sapidus) as alternative protein sources. Although growth performance decreased, biochemical analyses revealed adaptive metabolic responses. This approach offers a dual benefit: reducing fishmeal dependence while managing invasive populations, contributing to biodiversity conservation and resource recycling. Collectively, this research advances functional feed design by demonstrating nucleotides' immunomodulatory potential and validating ecological ingredients from IMTA and invasive species management. These findings support a paradigm integrating nutritional innovation with ecological responsibility to enhance resilience, productivity, and sustainability in marine fish farming.