The impact of different rearing condition on gilthead seabream welfare: Dissolved oxygen levels and stocking densities

Abstract

Aquaculture's success highly depends on a controlled rapid growth of organisms with minimal costs associated. Growth and welfare of reared organisms are affected by physical, chemical, and biological parameters. Following factors can be highlighted as crucial: density, pH, salinity, temperature, dissolved oxygen (DO), and nutrients (nitrogen, phosphorus, etc.). Relationship between fish density and oxygen's optimum levels is essential for designing the performance of each species. Furthermore, it is also necessary to study fish stress factors and physiological responses. Two rearing experiments with gilthead seabream (Sparus aurata) were performed, in order to test different densities (5, 10 and 20 kg/m3) for 9 weeks (271 ± 1.9 g) and to test different levels of oxygen (40%–60%, 60%–80%, and 80%–100%) for 6 weeks (316.3 ± 1.73 g). In both experiments, physiology and growth parameters were analysed, as well as water quality. This study showed that no relation was observed between density and fish physiology, but there structural (gill lesions) and physiological changes (haematocrit) were observed for seabream reared at low levels of DO.

Yucca schidigeraextract mediated the growth performance, hepato‐renal function, antioxidative status and histopathological alterations in Nile tilapia (Oreochromis niloticus) exposed to hypoxia stress

“…Araújo‐Luna et al. (2018) reported that the most frequent damage in gills documented was hyperplasia and cellular anomalies (degeneration and necrosis), with congestion in the secondary lamellae. Moreover, the potential impact of yucca on the protection of fish tissues from the harmful influences of hypoxia is not well documented.…”

Targeting the Mild-Hypoxia Driving Force for Metabolic and Muscle Transcriptional Reprogramming of Gilthead Sea Bream (Sparus aurata) Juveniles

“…The first sign of a mismatch between O 2 supply and demand is the reduction of appetite, varying the O 2 threshold level for maximal feed intake in Atlantic salmon ( Salmo salar ) and gilthead sea bream ( Sparus aurata ) between 40% and 75% saturation within the range of temperature tolerance [ 17 , 18 ]. This threshold level is decreased at high stocking densities [ 19 , 20 , 21 ], probably due to the unbalanced production and scavenging of reactive O 2 species (ROS) [ 22 ]. However, acclimation to one stressor can also improve the capacity to cope with another critical co-occurring stressor, and warm acclimation improves the hypoxia tolerance in Atlantic killifish ( Fundulus heteroclitus ) [ 23 ].…”

Tissue-Specific Orchestration of Gilthead Sea Bream Resilience to Hypoxia and High Stocking Density

“…Indeed, Arctic charr ( Salvelinus alpinus ) or meager ( Argyrosomus regius ) kept at high stocking densities evidenced a better growth performance than fish reared at low densities as long as water quality was preserved (Jørgensen et al, 1993; Millán-Cubillo et al, 2016). The impact of crowding stress can also be minimized when O 2 levels are not below LOS (Ruer et al, 1987; Araújo-Luna et al, 2018). Unraveling the combined effects of hypoxia and high rearing density are, thereby, crucial to warrant welfare during intensive fish farming.…”