Gilthead Seabream Sparus Aurata Research Articles

Oxidative status and intestinal health of gilthead sea bream (Sparus aurata) juveniles fed diets with different ARA/EPA/DHA ratios

The present work assessed the effects of dietary ratios of essential fatty acids, arachidonic (ARA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), on liver and intestine oxidative status, intestinal histomorphology and gut microbiota of gilthead sea bream. Four isoproteic and isolipidic plant-based diets were formulated containing a vegetable oil blend as the main lipid source. Diets were supplemented with ARA/EPA/DHA levels (%DM) equivalent to: 2%:0.2%:0.1% (Diet A); 1.0%:0.4%:0.4% (Diet B); 0%:0.6%:0.6% (Diet C); 0%:0.3%:1.5% (Diet D) and tested in triplicate groups for 56 days. Lipid peroxidation was higher in fish fed diets C and D while no differences were reported between diets regarding total, oxidized, and reduced glutathione, and oxidative stress index. Glutathione reductase was higher in fish fed diet A than diets C and D. No histological alterations were observed in the distal intestine. Lower microbiota diversity was observed in intestinal mucosa of fish fed diet C than A, while diets C and D enabled the proliferation of health-promoting bacteria from Bacteroidetes phylum (Asinibacterium sp.) and the absence of pathogenic species like Edwardsiella tarda. Overall, results suggest that a balance between dietary ARA/EPA + DHA promotes gilthead sea bream juveniles’ health however higher dietary content of n-3 LC-PUFA might limited the presence of microbial pathogens in intestinal mucosa.

Swimming Performance and Oxygen Consumption as Non-lethal Indicators of Production Traits in Atlantic Salmon and Gilthead Seabream.

The aim of this study was to investigate swimming performance and oxygen consumption as non−lethal indicator traits of production parameters in Atlantic salmon Salmo salar L. and Gilthead seabream Sparus aurata L. A total of 34 individual fish of each species were subjected to a series of experiments: (1) a critical swimming speed (Ucrit) test in a swim-gutter, followed by (2) two starvation-refeeding periods of 42 days, and (3) swimming performance experiments coupled to respirometry in swim-tunnels. Ucrit was assessed first to test it as a predictor trait. Starvation-refeeding traits included body weight; feed conversion ratio based on dry matter; residual feed intake; average daily weight gain and loss. Swim-tunnel respirometry provided oxygen consumption in rest and while swimming at the different speeds, optimal swim speed and minimal cost of transport (COT). After experiments, fish were dissected and measured for tissue weights and body composition in terms of dry matter, ash, fat, protein and moist, and energy content. The Ucrit test design was able to provide individual Ucrit values in high throughput manner. The residual Ucrit (RUcrit) should be considered in order to remove the size dependency of swimming performance. Most importantly, RUcrit predicted filet yield in both species. The minimal COT, the oxygen consumption when swimming at Uopt, added predictive value to the seabream model for feed intake.

Radiological characterization of gilthead seabream (Sparus aurata) fat by X-ray micro-computed tomography

In fish, the fat content contributes to promoting the nutritional and organoleptic characteristics of the flesh, which is crucial for consumer acceptance. Methods to predict the fat in fish are important in nutritional and physiological research, where body content is traditionally determined by dissection followed by chemical analysis. However, X-ray micro-computed tomography (micro-CT) provides three-dimensional information in a non-destructive way. This work aims to characterize radiologically the fat, in situ, in a widely cultivated marine species, gilthead seabream (Sparus aurata). To validate the method changes in fat content in a control group (fed) and another group (unfed for 60 days) were assessed. Fish images were acquired on an Albira SPECT/PET/CT preclinical-scanner. Image analysis and measurements were performed using the Carestream Molecular Imaging Albira CT system in conjunction with Pmod and Amide packages. By micro-CT analysis the density values were determined for the whole fish body (− 1,000 to + 2,500 HU, Hounsfield units), and density ranges for the fat in S. aurata were established from − 115 to + 50 HU. As expected, significant differences were found between fed and starved groups at 60 days. The present study confirms the usefulness of high-resolution morphological analysis for evaluating the presence and distribution of fat in this important fish species.

Effect of a functional feed additive on mitigation of experimentally induced gilthead sea bream Sparus aurata enteromyxosis.

In gilthead sea bream Sparus aurata, infection by Enteromyxum leei produces a cachectic syndrome with anorexia, weight loss, severe epaxial muscle atrophy and, eventually, death. Currently, there are neither vaccines nor effective prescription medicines to control this infection. Nutraceutical approaches are raising interest in the aquaculture industry, responding to the lack of therapeutic tools for the management of insidious chronic losses due to parasites. In this study, the effect of a commercially available health-promoting feed additive (SANACORE® GM) at 2 different doses was tested in comparison with a basal diet without the additive during a laboratory-controlled challenge with E. leei. Group performance and biometrical values were monitored, and an in-depth parasitological diagnosis, quantification of parasite loads and histopathological examination were carried out at the end of the trial. Supplemented diets mitigated the anorexia and growth arrestment observed in challenged fish fed the basal diet. This mitigation was maximum in the highest dose group, whose growth performance was not different from that of unchallenged controls. Treated groups also presented lower prevalence of infection and a lower parasite load, although the differences in the mean intensity of infection were not statistically significant. Although the decrease in parasite levels was similar with both doses of additive tested, the pathogeny of the infection was mostly suppressed with the higher dose, while only mitigated with the lower dose. The mechanisms involved in the effects obtained remain to be investigated, but the results point to a modulation of the immunopathological response to the infection.

Effects of graded levels of minerals in a multi‐nutrient package on Gilthead sea bream (Sparus aurata) fed a plant‐based diet

Effects of graded levels of minerals in a multi‐nutrient package on Gilthead sea bream (<i>Sparus aurata</i>) fed a plant‐based diet

Vegetated Habitats Trophically Support Early Development Stages of a Marine Migrant Fish in a Coastal Lagoon

Understanding the trophic ecology of early developmental stages of commercial fish species migrating between sea and coastal lagoons is crucial to effective management of nursery habitats and resulting resources. While most information on diet shift of the gilthead seabream Sparus aurata comes from studies in experimental conditions, here we investigated the trophic niche dynamics of post-larvae, juveniles and sub-adults in natural environment, hypothesising that habitat and resources use of marine and lagoonal sites will exhibit strong relationship with ontogeny of the species. Carbon and nitrogen stable isotopes showed evidence of a clear shift in the trophic niche features, trophic position and trophic pathways supporting S. aurata during growth. Main differences occurred between post-larvae and juveniles/sub-adults, perfectly matching their diet shift from zooplanktivorous to zoobenthivorous habits. The wider trophic niche of juveniles exploiting the variety of resources within the lagoon, compared to the narrower niche of marine post-larvae demonstrates the importance of the trophic role of the lagoon as nursey ground, where aquatic macrophytes (seagrasses and macroalgae) provide the main trophic support as sources of organic matter.

Modulation of Pituitary Response by Dietary Lipids and Throughout a Temperature Fluctuation Challenge in Gilthead Sea Bream

Low temperatures provoke drastic reductions in gilthead sea bream (Sparus aurata) activity and nourishment, leading to growth arrest and a halt in production. However, scarce data exist concerning the implications of central core control during the cold season. The aim of this work was to study the effects of low temperature and recovery from such exposure on the pituitary activity of sea bream juveniles fed 18% or 14% dietary lipid. A controlled indoor trial was performed to simulate natural temperature fluctuation (22 °C to 14 °C to 22 °C). Meanwhile, we determined the regulatory role of the pituitary by analyzing the gene expression of some pituitary hormones and hormone receptors via qPCR, as well as plasma levels of thyroidal hormones. In response to higher dietary lipids, hormone pituitary expressions were up-regulated. Induced low temperatures and lower ingesta modulated pituitary function up-regulating GH and TSH and thyroid and glucocorticoid receptors. All these findings demonstrate the capacity of the pituitary to recognize both external conditions and to modulate its response accordingly. However, growth, peripheral tissues and metabolism were not linked or connected to pituitary function at low temperatures, which opens an interesting field of study to interpret the hypothalamus–pituitary–target axis during temperature fluctuations in fish.

Animal Welfare in Fish Aquaculture: Stress Attenuation through the Diet and the Use of Anesthetics during Transport

Fish aquaculture generates stressful situations that reduce animal welfare conditions and the economic benefits. In this article, we expose two possibilities for stress attenuation in the gilthead seabream ( Sparus aurata L.), an emblematic species for the national and European aquaculture.

The influence of organic versus conventional feeding on the growth and survival of gilthead sea bream Sparus aurata L. juveniles

The influence of organic versus conventional feeding on the growth and survival of gilthead sea bream Sparus aurata L. juveniles

Proteomic characterization of primary cultured myocytes in a fish model at different myogenesis stages

Myogenesis is a complex two-phase process of proliferation and differentiation, which seems to be greatly conserved in vertebrates. For the first time in fish, we identify the changes that occur in the proteome during this process in a gilthead sea bream (Sparus aurata) myocyte primary cell culture (on days 4, 8 and 12), using 2-D gel electrophoresis and LC-MS/MS. A significant increase of myogenin expression at day 8 marked the transition from proliferation to differentiation. Of the 898 spots in the proteome analysis, the 25 protein spots overexpressed on day 4 and the 15 protein spots overexpressed on day 8 indicate the end of proliferation and the beginning of differentiation, respectively. Proliferation was characterized by enrichment of proteins involved in actin cytoskeleton remodelling and in cellular metabolic processes (transcription, ubiquitination, response to stress and glucose metabolism). During differentiation, 41 proteins were overexpressed and 51 underexpressed; many of them related to biosynthetic processes (RNA and protein synthesis and folding, and pentose pathways), terminal myotube formation and muscle contraction. The main cellular processes of both phases of muscle development in fish are similar with those observed in mammals but extended in time, allowing sequential studies of myogenesis.

Muscle bioenergetics of two emblematic Mediterranean fish species: Sardina pilchardus and Sparus aurata

We investigated links between swimming behavior and muscle bioenergetics in two emblematic Mediterranean fish species that have very different ecologies and activity levels. European sardines Sardina pilchardus are pelagic, they swim aerobically, school constantly and have high muscle fat content. Gilthead seabream Sparus aurata are bentho-pelagic, they show discontinuous spontaneous swimming patterns and store less fat in their muscle. Estimating the proportion of red and white muscle phenotypes, sardine exhibited a larger proportion of red muscle (~10% of the body mass) compared to gilthead seabream (~5% of the body mass). We firstly studied red and white muscle fiber bioenergetics, using high-resolution respirometers, showing a 4-fold higher oxidation capacity for red compared to white muscle. Secondly, we aimed to compare the red muscle ability to oxidize either lipids or carbohydrates. Sardine red muscle had a 3-fold higher oxidative capacity than gilthead seabream and a greater capacity to oxidize lipids. This study provides novel insights into physiological mechanisms underlying the different lifestyles of these highly-prized species.

Dietary arginine and citrulline supplementation during a short-term feeding period improves the gilthead seabream (Sparus aurata) immune status

Dietary arginine and citrulline supplementation during a short-term feeding period improves the gilthead seabream (Sparus aurata) immune status

Morphological and histological characterization of an ectopically mineralized structure in a gilthead sea bream Sparus aurata with opercular deformation.

In this study, we describe an abnormal ectopically mineralized structure (EMS) that was found inside the skull of a juvenile Sparus aurata that also showed a bilateral opercular deformation. The overall phenotype and tissue composition were studied using micro-CT scanning and histological analyses. The ectopic structure occupies a large volume of the brain cavity, partially extruding into the gill cavity. It shows a dense mineralization and an extracellular matrix-rich phenotype, with variation in both the morphology and size of the cell lacunae, combined with an irregular fibre organization inside the matrix. This study is the first to report such an EMS in a juvenile teleost fish, where the tissue does not resemble any other connective tissue type described in bony fish so far. The tissue phenotype seems to rule out that the EMS corresponds to a tumorous cartilage. Yet, it is rather reminiscent of a highly mineralized structure found in cartilaginous fish, where it is suggested to be associated with damage repair.

Effects of dietary orange peel on growth performance, antioxidant activity, intestinal microbiota and liver histology of Gilthead sea bream ( Sparus aurata ) larvae

Effects of dietary orange peel on growth performance, antioxidant activity, intestinal microbiota and liver histology of Gilthead sea bream ( <i>Sparus aurata</i> ) larvae

Arginine Vasotocin and Cortisol Co-regulate Vasotocinergic, Isotocinergic, Stress, and Thyroid Pathways in the Gilthead Sea Bream (Sparus aurata).

In teleosts, a complex interaction between several endocrine axes modulates physiological functions related to metabolism, stress, and osmoregulation. Although many studies in fish underline the interconnection between the hypothalamic–pituitary–interrenal (HPI) and hypothalamic–pituitary–thyroid (HPT) endocrine axes, their relationship with the vasotocinergic and isotocinergic systems remains unknown. The aim of the present study is therefore to shed light on the potential cross-regulations between HPT, HPI, and the vasotocinergic and isotocinergic axes in gilthead sea bream (Sparus aurata) at hypothalamic, hypophyseal, and plasma levels. Sea breams were administered with intraperitoneal slow-release implants containing different doses of vasotocin (the active peptide in vasotocinergic system) or cortisol (the last component of HPI axis). Plasma osmolality was higher in active neuropeptides vasotocin (Avt)-treated fish, indicating an osmoregulatory function of this hormone. Low concentrations of Avt increased hypothalamic arginine vasotocin precursor (avt) mRNA levels and increased Avt storage in the pituitary. Avt treatment down-regulated hypothalamic arginine vasotocin receptor v1a-type (avtrv1a), suggesting a negative paracrine co-regulation of the HPI axis due to the close location of avtrv1a and adrenocorticotropin hormone (Acth) cells in the anterior pituitary. Furthermore, the up-regulation observed in arginine vasotocin receptor v2-type (avtrv2) suggests their involvement in metabolic and cortisol-related pathways in the hypothalamus. The decrease in isotocin (It) pituitary storage and the up-regulation of it receptor, observed in the Avt-treated group, reinforce the idea of an interconnection between the vasotocinergic and isotocinergic systems. Cortisol and Avt administration each inhibited the HPI axis, down-regulating crh gene expression in the absence of variations in corticotropin releasing hormone binding protein (crhbp). Finally, both hormonal treatments activated the HPT axis via up-regulation of trh and down-regulation of thrb. Our results provide evidence for strong interactions among the Avt/It, HPI, and HPT axes of marine teleosts, particularly at the hypothalamic level.

Morphological and ecophysiological adaptations of wild gilthead seabream Sparus aurata associated with tuna farms

Morphological and ecophysiological adaptations of wild gilthead seabream Sparus aurata associated with tuna farms

The genetic population structure and temporal genetic stability of gilthead sea bream Sparus aurata populations in the Aegean and Ionian Seas, using microsatellite DNA markers.

We examined 662 gilthead sea bream Sparus aurata from wild samples of the species in the Aegean and Ionian Seas, using 20 EST-linked microsatellite markers, in three multiplex panels, as well as seven anonymous loci. Most of the markers were revealed to be highly polymorphic. We found low genetic differentiation between the sampling stations/areas with total FST 0.002 (P < 0.05). Based on comparison of five temporal samples, our results indicate genetic data consistency over time for all tested samples, pointing to stable populations, despite reported repeated escape events. Our results confirm the genetic population structure previously observed in these specific areas, using by far more markers than in previous studies in both coding and non-coding DNA loci. The limited genetic structure and the temporal genetic stability indicate neither major genetic differentiation of local populations by geographic isolation nor influence from anthropogenic factors. These results provide a baseline for future reference in any management programme of both wild and farmed population of S. aurata as well as of other aquaculture species with a potential introgression among farmed and wild populations.

Reproductive success of a marine teleost was correlated with proactive and reactive stress-coping styles.

The present study investigated the relationship between reproductive success and stress-coping styles in gilthead seabream Sparus aurata in captivity. To characterise stress-coping styles, a total of 22 breeders were submitted to three different individual-based tests, one group-based test and post-handling glucocorticoid quantification. To assess spawning participation, a microsatellite analysis was performed on a total of 2698 larvae, which allowed each offspring to be assigned unambiguously to a single parental couple. Overall, S. aurata showed defined proactive and reactive behavioural traits. Proactive breeders exhibited higher levels of activity and risk taking and lower glucocorticoid blood levels than reactive breeders. The stress-coping style traits were consistent over time and context (different tests). Breeders that contributed to a higher number of progeny exhibited proactive behaviours, while those showing low progeny contribution exhibited reactive behaviour. Therefore, breeders with a high proportion of progeny (> 20%) had significantly higher activity and risk taking and lower cortisol than breeders with low progeny contribution (< 20%). In addition, males were more proactive than females and males exhibited significantly higher activity, risk taking and lower cortisol than females. This study is the first to establish in S. aurata breeders: (a) a relationship between stress-coping styles and spawning success; (b) a relationship between stress-coping styles and gender; and (c) the existence of proactive and reactive traits at the adult stage.

Effects of food quantity and distribution on aggressive behaviour of gilthead seabream and European seabass

In intensive aquaculture, aggression among fish creates a disturbed social environment and leads to serious implications. Food is a resource of great importance for fish and its acquisition is an important enough reason for increased competition. Gilthead seabream Sparus aurata and European seabass Dicentrarchus labrax are the two main reared species of the Mediterranean aquaculture and known to exhibit aggressive behaviour. The present study aimed at investigating the effects of food quantity (low and high feeding ration, i.e. 1% and 3% of body mass) and method of food distribution (localised and dispersed) in the aggressive behaviour of these two species (mean initial body mass 39 g), before, during and after feeding. Analyses of data obtained showed that: a) Both species are most aggressive during feeding. b) In the case of gilthead seabream, aggression is intensified when fish are fed a low feeding ration, while the method of food distribution has no effect on aggression. However, a higher degree of social stress in feeding and non-feeding periods is indicated when the low feeding ration is distributed locally (i.e. appearance of dark vertical bands on the body). c) In the case of European seabass, aggression is intensified not only during feeding but also before and after feeding, especially at the low feeding ration under localised feeding. d) In both species aggressive acts are mainly biting and chasing, but the relative importance of each behavioural pattern is differently expressed in each species, especially before and after feeding. Present results add to a better understanding of gilthead seabream and European seabass aggression and could help towards an improved feeding practice in these species intensive rearing. Feeding an adequate amount of food and distributing it in a dispersed way can appease fish competition and spare energy for growth, thus providing for fish welfare and productivity.

Prevalence of nervous necrosis virus (NNV) and Streptococcus species in wild marine fish and crustaceans from the Levantine Basin, Mediterranean Sea.

Infectious diseases in marine animals have ecological, socio-economic and environmental impacts. Nervous necrosis virus (NNV) and Streptococcus iniae have become major threats to marine aquaculture and have been detected in morbid marine organisms worldwide. However, despite their importance, there is a lack of knowledge regarding the prevalence of these pathogens in wild fish species. Here we sampled indigenous and Lessepsian species from different trophic levels and different biological niches in the eastern Mediterranean. A total of 174 fish and 32 crustaceans were tested for S. iniae and a total of 195 fish and 33 crustaceans were tested for NNV. We found an overall prevalence of 9.71% Streptococcus spp. and 21.49% NNV in selected marine fish and crustaceans by PCR and qPCR. In fish, the zoonotic agent S. iniae was detected at a higher prevalence in kidney compared to liver tissue. Co-infection by both pathogens was detected only in 5 specimens. We also examined gilthead sea bream Sparus aurata from an Israeli offshore marine farm during the grow-out period, in order to assess the possibility of horizontal pathogen transmission from wild to maricultured fish. Three out of 15 (20%) fish were found to be NNV positive after 120 d in the sea, suggesting spontaneous transmission from wild to farmed fish. Our findings suggest that more surveys should be conducted, especially in areas were mariculture farms are planned to be established.