The ontogeny of greater amberjack digestive and antioxidant defence systems under different rearing conditions: A histological and enzymatic approach

An overall synchronization of morphological and physiological ontogenetic events of the digestive and antioxidant defence systems occurred in greater amberjack (Seriola dumerili) larvae reared under intensive (INT) or semi‐intensive (MES) conditions for 30 days. The first differentiations of the digestive channel took place at 3–4 days post‐hatch (dph) (3.6–3.7 mm). Differentiation of the endocrine and exocrine pancreas begun at 4–5 dph (4.0–4.1 mm), coinciding with a decrease in carbohydrase activity from egg to the onset of exogenous feeding and the maintenance of bile salt‐activated lipase and total alkaline proteases. The first gastric glands and pepsin activity were evident at 17–20 dph (5.5–6.2 mm) in both fish groups. The appearance of pyloric caeca had a 5‐day delay in the INT compared to the MES larvae (28 versus 23 dph). Antioxidant enzyme activities decreased progressively from 7 to 30 dph in both rearing conditions. However, GPx, SOD at 7 and 18 dph, and GST activities were higher in the INT larvae. Although both larval groups did not globally differ in somatic growth and maturation of digestive function, it seems that the antioxidant defence system of MES larvae had to face less oxidative assaults, which may be attributed to lower stressful and more stable culture conditions.info:eu-repo/semantics/acceptedVersio

Surplus of dietary micronutrients promotes antioxidant defense and improves fin erosions in European seabass (Dicentrarchus labrax) fry

Dietary micronutrient supplementation can serve as skin health promotor to prevent from natural infections and can be applied to decrease the use of antibacterial agents and their impact on the environment. Such supplementation has indicated anti-inflammatory and antioxidant properties in farmed fish. In this study, dietary supplementation of zinc, selenium, ascorbic acid and niacin, at levels 2 to 3-fold higher than recommended, was evaluated as a measure to promote skin health and antioxidant defense in European seabass, Dicentrarchus labrax, fry. For this purpose, fish survival, growth performance, fin and skin erosions as well as whole-fish antioxidant enzyme activity (catalase, selenium (Se)-independent and dependent glutathione peroxidase) were assessed. Moreover, bacterial load in the rearing water and skin mucus were evaluated to assess the potential of the dietary micronutrient mixture as a preventive from natural infections. A group fed with a diet including these micronutrients at recommended levels served as a control. Surplus of these micronutrients significantly reduced the percentage of fish with eroded fins, while also induced the activity of catalase and Se-dependent glutathione peroxidase. Fish growth and bacterial loads in the water and fish skin mucus were not affected, whereas no skin lesions were observed. Overall, a mineral- and vitamin-supplemented diet at levels higher than recommended seems to act as a promotor of skin health and prevent from fin erosions, potentially through an increase in the antioxidant defense system.</p

Growth Performance and Environmental Quality Indices and Biomarkers in a Co-Culture of the European Sea Bass with Filter and Deposit Feeders: A Case Study of an IMTA System

This study aimed to evaluate the efficiency of an integrated multi-trophic aquaculture (IMTA) system comprising co-cultured fed fish and organic extractive species representing three distinct trophic levels as well as the impact and potential utilization of two commercially available fish feeds made up of 35% fish meal (FM) and 20% fish meal (LFM) ingredients, using a multi-indicator assessment approach. Significant alterations were observed in growth performance indicators (GPIs), water and sediment quality indices, toxicity tests and biomarkers within the IMTA system. The fish survival, weight gain (WG), and specific growth rate (SGR) were higher in the IMTA system with significantly lower feed conversion ratios (FCRs) and higher feed efficiency (FE) in comparison to the fed fish monoculture system. Yet, organic filter feeders displayed 100% survival, and increased shell growth, while deposit feeders exhibited successful survival and significant weight gain. In the comparison between FM-IMTA and LFM-IMTA, fed fish in FM-IMTA showed higher WG, SGR, and FE with lower FCR. Environmental parameters like temperature, oxygen, and nutrient concentrations fluctuated but generally improved in the IMTA system, indicating lower mesotrophic conditions. Sediment fatty acid profiles differed between systems and toxicity assessments, which suggested a lower impact in IMTA and FM-IMTA systems. The sediment microbial community displayed high similarity within IMTA systems and between FM-IMTA and LFM-IMTA. These findings underscore the potential of IMTA systems for sustainable aquaculture, emphasizing improved growth performance and reduced environmental impact, particularly when using fish meal feeds

Aquaculture Multi Trophique Intégrée : le projet IMTA Effect

National audienc

Aquaculture Multi Trophique Intégrée : le projet IMTA Effect

National audienc

AQUACULTURE MULTI-TROPHIQUE INTÉGRÉE Perspectives pour une aquaculture plus durable: Une nécessité pour répondre à la demande en produits aquatiques

Brochure de diffusion des résultats du projet ERANET-COFASP IMTA-EffectThe objective of the IMTA-Effect project, sup¬ported by EU ERANET-COFASP, was to provide new knowledge to sustain development of IMTA using experimental and modeling approaches. Seawater ponds (fish + filter feeders + depo¬sit feeders or macroalgae) were studied by IPMA in Portugal and HCMR in Greece. Rice-fi¬sh culture was studied by ISEM in Madagascar, and freshwater ponds in semi-separate systems for carp polyculture were studied by UDJG and Romfish in Romania, and for Azolla-Gourami in Indonesia. A compartmented IMTA that added planted lagoons to fish polyculture in freshwa¬ter ponds was studied by INRAE in France. Fi¬nally, RAS were studied by separating each spe¬cies into specific tanks by AUA in Greece and by ISEM (fish and macroalgae) and Ifremer (marine fish, phytoplankton, oysters, and ragworms) in France. The case studies showed that IMTA’s adapted management of interactions among species of different trophic groups improved the aqua¬culture system. Compared to a reference fish monoculture, the overall productivity of the sys¬tems can increase due to the production of other products or services. The efficiency of delivering feed to fish increases overall by recycling in the system loop, which decreases the environmental impacts. IMTA also diversifies aquatic products, which can increase the robustness of aquatic farms. We demonstrated the key role of prima¬ry producers (plants, micro- and macroalgae) as the engine of nutrient recycling. One advance of the IMTA-Effect project was made in system modeling. We characterized the energy distribu¬tion (DEB) of ragworms and modeled the food web structure in pond systems using Ecopath with Ecosim, combined with the use of C and N isotopes, which trace the fate of nutrients in the food web. The IMTA-Effect project was an op¬portunity to strengthen the knowledge and dif¬fusion of new practices in the aquaculture sector, thus opening new perspectives for development