Functional Feeds to Tackle Meagre (Argyrosomus regius) Stress: Physiological Responses under Acute Stressful Handling Conditions

Abstract

Marine algae are recognised sources of bioactive compounds that have attracted great interest as nutritional supplements for aquaculture fish. Intensive rearing conditions often expose fish to husbandry-related stressors, rendering fish more susceptible to disease and reducing production yields. The present work evaluated the potential of two marine algae extracts (Fucus vesiculosus and Nannochloropsis gaditana) as nutritional supplements to mitigate stress effects in meagre (Argyrosomus regius) exposed to an acute handling stress (AS). A plant-based diet was used as a control, and three other diets were prepared, which were similar to the control diet but supplemented with 1% of each algal extract or a combination of the two extracts (0.5% each). The effects of supplemented diets on stress biomarkers, antioxidant enzyme activities, and immune response were analysed in fish exposed to AS after 4 weeks of feeding. Supplemented diets did not affect growth performance but the inclusion of F. vesiculosus promoted higher feed efficiency, as compared to the control group. Dietary algal extracts supplementation reduced plasma glucose levels, increased white blood cell counts, and reduced the expression of pro-inflammatory genes when compared with the control. N. gaditana supplementation led to a reduction in hepatic antioxidant enzyme activity and glutathione levels, while F. vesiculosus supplementation increased muscle glutathione reductase activity and reduced lipid peroxidation. These findings support the potential of algal extracts as nutraceuticals in aquafeeds to enhance the ability of fish to cope with husbandry-related stressful conditions and ultimately improve fish health and welfare.

Effect of Tryptophan Dietary Content on Meagre, Argyrosomus regius, Juveniles Stress and Behavioral Response

“…Similarly, glucose levels increased after the stress test, especially in fish fed 0.5% tryptophan, potentially associated with heightened energy resources catabolism. In the primary stress response, cortisol release triggers a secondary response, leading to increased glucose levels and its transport to energy-demanding tissues for restoration [5,35,36]. This is consistent with the results obtained for the treatment with lower tryptophan content and coincident with those reported by Saavedra et al [24] for meagre, Abdel-Tawwab [35] for Nile tilapia and Hoseini et al [37] for sturgeon.…”

The Use of Tricaine Methanesulfonate (MS-222) in Asian Seabass (Lates calcarifer) at Different Temperatures: Study of Optimal Doses, Minimum Effective Concentration, Blood Biochemistry, Immersion Pharmacokinetics, and Tissue Distributions

“…The blood pH is decreased at the same time, because the accumulation of carbon dioxide increases the acidity of the blood [ 40 ]. Under hypoxic condition, the production of lactate is increased as an energy substrate for anaerobic respiration [ 41 , 42 ], which was the case in this study and short-horned sculpin ( Myoxocephalus scorpius ) [ 43 ]. It has been previously discovered that the increase in lactate level goes back to normal at 4 h post-anesthetic exposure in bonefish ( Albula vulpes ) and Atlantic salmon [ 41 , 44 ].…”

Microalgae with immunomodulatory effects on fish

“…65,92 Recently, the ability of the genus Nannochloropsis to reduce the effects of different types of stress related to aquaculture has been explored. On the one hand, Monteiro et al 93 showed that Tackle Meagre (Argyrosomus regius) supplemented with N. gaditana at 1% and subjected to acute handling stress had lower gene expression of proinflammatory cytokines tnf-α and il-1β genes, as well as a lower number of parameters related to oxidative stress. On the other hand, Abdelghany et al 66 found that the dietary administration of Nannochloropsis oculata at 10% and 15% to Nile tilapia (O. niloticus) subjected to air stress and then challenged with Aeromonas veronii induced greater protection compared with control fish.…”