Maulvault, Ana Luísa Marques Paixão de CarvalhoRepolho, Tiago Filipe Baptista da Rosa, 1974-Chainho, Tomás Antunes2025-01-0220242024http://hdl.handle.net/10400.5/96757Tese de mestrado, Ecologia Marinha, 2024, Universidade de Lisboa, Faculdade de CiênciasAquaculture has become increasingly crucial in ensuring global food security amid growing populations and environmental challenges. Still, its sustainability faces two major bottlenecks: 1) disease outbreaks and 2) climate change impact. This study aimed to assess the effectiveness of aquafeeds biofortified with Laminaria digitata as an eco-innovative approach to improve the welfare, growth performance, immunocompetence and tissue biochemical responses of juvenile Sparus aurata experimentally exposed to a category III Mediterranean marine heatwave (MHW) scenario and challenged with a pathogenic bacterium (Vibrio harveyi). Four experimental feeding treatments were carried: i) a commercial control diet without seaweed supplementation (CTR); ii) a diet supplemented with 0.3% Laminaria digitata (P0.3%; iii) a diet supplemented with 1.5% Laminaria digitata (P1.5%); and iv) a diet supplemented with 0.3% Laminaria digitata extract (E0.3%). After 30 days of prophylactic biofortification treatment, fish were defied with a simulated category III Mediterranean MHW (25.7ºC) and subsequently infected (through intraperitoneal injection) with an inoculum of a virulent strain of V. harveyi (0.49x109 CFU/mL). Animal welfare, performance and post-infection survival were assessed. Key biochemical markers indicative of oxidative stress (catalase - CAT, glutathione S-transferase - GST, lipid peroxidation - LPO) protein degradation (ubiquitin content - UBI), heat shock response (HSP70/HSC70 content) and metabolism (lactate dehydrogenase - LDH) were determined upon biofortification (T1) and exposure to the MHW (T2). Results indicated that biofortification with L. digitata, particularly with 0.3% of extract inclusion (E0.3%), significantly enhanced antioxidant defence, reduced lipid peroxidation, and improved overall fish welfare under stress conditions. As for the effects of MHWs, data highlighted decreased fish health due to increased oxidative stress and impaired growth performance. The research in this MSc thesis underscores the importance of optimising biofortification strategies to enhance the resilience of farmed Sparus aurata in the face of climate change.engAquaculturaalterações climáticasalimentos funcionaisbem-estar animalbiomarcadoresTeses de mestrado - 2024master thesis203877500