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Host–pathogen interactions and the design of vaccines for aquaculture fish viruses are challenging and call for innovative approaches. This study explores the potential of adenoviral (Ad) vectors Ad5 and chimeric Ad5/40 as gene delivery tools for fish brain cells susceptible to neurotropic viruses. For this purpose, European sea bass (Dicentrarchus labrax) DLB-1 and gilthead seabream (Sparus aurata) SaB-1 brain cell lines were infected with Ad5 or Ad5/40 vectors expressing GFP, and we evaluated their capacity for infection by fluorescence microscopy and flow cytometry, as well as their antiviral innate immune response by the transcription of gene markers (irf3 and mx). We found that both vectors are able to infect DLB-1 and SaB-1 brain cell lines to similar levels, as demonstrated by fluorescence microscopy and flow cytometry, though the infection efficiency was low. In addition, infection with Ad vectors regulated the transcription of genes related to the interferon-mediated antiviral immune response. Our results indicate that the Ad5/40 vector achieves better infection and consistent cellular distribution. These findings suggest that these vectors may offer targeted gene delivery and local immune responses. [ABSTRACT FROM AUTHOR]

To evaluate the effects of mussel meal, as a sustainable ingredient for fish feed, on the growth, health status, proximate composition, and fatty acid profile of gilthead seabream, mussel meal was included in commercial feed formulations. Sunflower oil (2%) was used as a binding agent. Four groups of gilthead seabream were fed either with control feed (commercial feed, commercial feed and sunflower oil) or mussel-meal-supplemented formulations (commercial feed, sunflower oil, and 2.5 or 5% mussel meal) for six weeks. In this experiment, a total of 180 specimens of gilthead seabream juveniles were included. The initial weight and length of the gilthead seabream specimens were, on average, 13.04 g and 9.57 cm, respectively. The average temperature of the seawater ranged between 25 and 26 °C during the experiment. The results of this study indicated a higher relative weight gain and a slightly lower feed conversion ratio in the control group fed with commercial feed, probably because of macronutrient imbalances introduced by the addition of mussel meal and sunflower oil. The groups fed with mussel-supplemented diets had a slightly lower crude protein content compared to the group fed with a commercial diet. The addition of sunflower oil and mussel meal decreased the saturated fatty acid content while increasing the monounsaturated and polyunsaturated fatty acid content compared to the control group. However, the high content of DHA and EPA in the mussel meal resulted in a proportional increase of these fatty acids in the muscle tissue of gilthead seabream, although the overall effect was not statistically significant. The findings of this study suggest that mussel meal is a promising source of protein and lipids for sustainable fish feed production, but under the experimental setup, mussel meal did not act as an attractant for increasing fish feed intake during the summer conditions. [ABSTRACT FROM AUTHOR]

The gilthead seabream (Sparus aurata) is cultured throughout the Mediterranean; the sea temperature most significantly determines the duration of farming. Sea temperatures reduce gilthead seabream’s need for feed and fish growth is not expected in these conditions. It is hypothesized that improving feed formulation could improve growth during the winter months. For the research, two groups were formed, and fed for a month with two types of fish feed of different nutritional composition at an average temperature of 13.9 ± 0.90 °C. The fish from cage A (21.53 ± 1.53 cm; 173.77 ± 38.24 g) were fed fish feed containing protein and lipid 100% from marine origin (H1). The fi sh from cage B (22.17 ± 1.43 cm; 181.08 ± 43.05 g) were fed with commercial feed for gilthead seabream, whose proteins and lipids were partially replaced by plant raw materials (H2). The temperature was measured daily and samples were taken at the beginning and end of the experiment for biometrics, which included the fish’s total length, total weight, and condition factor. This study showed that fish fed with a modifi ed formula achieved higher growth parameters than fish fed with commercial feed. The data obtained indicate that gilthead seabream can grow at low temperatures and there is a need for further research to ensure the correct selection of raw materials for the testing and production of feed for the period of low sea temperatures. [ABSTRACT FROM AUTHOR]

Abstract Extractive fisheries and marine aquaculture share space and target species. Several regional-scale examples exist of escapees entering wild fisheries landings, yet no study has assessed the influence of aquaculture on landings at an ecosystem scale. We examined the effects of farmed fish escapes on fisheries using FAO data and published escape rates for Gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax). Seabream landings were significantly correlated with the estimated biomass of escaped seabream entering the wild. There was a similar pattern for seabass until 2005, but the overall relationship between landings and escapes was not significant due to the dramatic drop in catches in recent years. We argue that seabass escapees’ relatively high mortality, lower capturability, and minor ‘leaking’ from farms may obscure their influence on landings. Significant positive fisheries regime shifts were detected for both species, matching the onset of aquaculture in the Mediterranean and the period when escapees from aquaculture surpassed landings. Our results suggest that fish escapes of these two iconic species may mask wild stock overexploitation, confound stock assessments, alter genetic diversity, increase the risk of spreading pathogens and parasites, and compete with wild conspecifics while boosting fisheries landings.

Extractive fisheries and marine aquaculture share space and target species. Several regional-scale examples exist of escapees entering wild fisheries landings, yet no study has assessed the influence of aquaculture on landings at an ecosystem scale. We examined the effects of farmed fish escapes on fisheries using FAO data and published escape rates for Gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax). Seabream landings were significantly correlated with the estimated biomass of escaped seabream entering the wild. There was a similar pattern for seabass until 2005, but the overall relationship between landings and escapes was not significant due to the dramatic drop in catches in recent years. We argue that seabass escapees' relatively high mortality, lower capturability, and minor 'leaking' from farms may obscure their influence on landings. Significant positive fisheries regime shifts were detected for both species, matching the onset of aquaculture in the Mediterranean and the period when escapees from aquaculture surpassed landings. Our results suggest that fish escapes of these two iconic species may mask wild stock overexploitation, confound stock assessments, alter genetic diversity, increase the risk of spreading pathogens and parasites, and compete with wild conspecifics while boosting fisheries landings. [ABSTRACT FROM AUTHOR]

Simple Summary: Vitamin D3 and vitamin K3 each play a crucial role in the growth, skeletal development, and regulation of bone biomarkers and calcium homeostasis in larval and juvenile gilthead seabream. Although their interaction has been shown to influence these parameters in animals and humans, there is limited research on this interaction in fish. In this study, juvenile gilthead seabream was fed diets with varying combinations of vitamin D3 and K3. The results showed no significant effects on growth, serum calcitriol levels, or morphometric parameters. However, a significant impact was observed on bone biomarkers and calcium-regulating genes across different tissues. Additionally, there was an increasing tendency of skeletal anomalies with higher vitamin levels. These findings suggest that, while dietary vitamin D3 and K3 can modulate bone biomarkers and calcium-regulating genes in fish, they do not significantly influence growth or serum calcitriol, likely due to the size and developmental stage of the fish. Based on this, we recommend considering vitamin D3 and K3 in diets to support skeletal health but note that they may not yield substantial changes in growth outcomes for juvenile gilthead seabream. The interaction between vitamin D and vitamin K is crucial for regulating bone metabolism and maintaining calcium homeostasis across diverse animal species due to their complementary roles in calcium metabolism and bone health. However, research on this interaction of vitamin D and K in fish, particularly Mediterranean species like gilthead seabream, is limited or not studied. This study aimed to understand the effects of different dietary combinations of vitamin D3 and K3 on juvenile gilthead seabream. Accordingly, seabream juveniles were fed with varying combinations of vitamin D3/vitamin K3 (mg/kg diet) for 3 months: (0.07/0.01), (0.20/0.58), (0.19/1.65), (0.51/0.74), (0.56/1.00). At the end of the trial, survival, growth, body morphology, serum calcitriol, and vertebral mineral composition remained unaffected by varying vitamin levels, while gene expression patterns related to bone formation, resorption, and calcium regulation in various tissues were significantly influenced by both vitamins and their interaction. Gilthead seabream juveniles fed the 0.07/0.01 mg/kg diet upregulated calcium-regulating genes in the gills, indicating an effort to enhance calcium absorption to compensate for dietary deficiencies. Conversely, an increase in vitamin D3 and K3 up to 0.19 and 1.65 mg/kg, respectively, upregulated bone formation, bone remodeling, and calcium homeostasis-related gene expression in vertebra and other tissues. On the contrary, a dietary increase in these vitamins up to 0.56 mg/kg vitamin D3 and 1.00 mg/kg vitamin K3 downregulated calcium metabolism-related genes in tissues, suggesting an adverse interaction resulting from elevated levels of these vitamins in the diet. Hence, sustaining an equilibrium in the dietary intake of vitamin D3 and vitamin K3, in an appropriately combined form, may potentially induce interactions between the vitamins, contributing to favorable effects on bone development and calcium regulation in gilthead seabream juveniles. [ABSTRACT FROM AUTHOR]

Classical assessments of new fish feeds are anthropocentric, focusing mainly on growth. Although this methodology is accurate, it does not consider the fish' perspective. This study aimed to investigate the behavioural responses and feed preferences of Nile tilapia (Oreochromis niloticus) and gilthead seabream (Sparus aurata) through a self-selection trial using self-feeders. Both species were offered three feeds: a control (PD) commercial-like feed and two diets (ORG1 and ORG2) formulated with different inclusions of alternative ingredients to address some of the current environmental concerns and/or ethical issues often associated with commercial formulations. Three groups of tilapia with an average weight of 163.0 g ± 4.3 g (mean ± SD) and four groups of seabreams with 174.7 g ± 27.0 g were tested. Tilapia exhibited a preference for ORG2 (46.5%), influenced by the sensory properties of the feed and post-ingestion signals. Seabream did not show a preference for any feed. These findings highlight the effectiveness of self-selection experiments in allowing fish to express their feeding behaviour and preferences. Therefore, this approach should be considered in the initial screening and design of new aquaculture feeds and ingredients. [ABSTRACT FROM AUTHOR]

Spawning performance -relative fecundity and fertilization success-was studied in two hatchery-reared broodstocks of gilthead seabream (Sparus aurata) held under relatively constant well-water temperature (18-20 °C) and simulated natural photoperiod, for five consecutive spawning seasons, between 3 and 7 years of age. The spawning season lasted between 4 and 6 months each year, and the total number of eggs produced annually ranged between 1 480 000 and 3 100 000 eggs/kg female body weight, being the highest during the first and second spawning season. No difference was observed in monthly relative fecundity between years -although high variation existed within years, whereas fertilization success was the highest during the second and third reproductive season, and dropped significantly during the last year of the study. The male percentage of the broodstocks was 35% during the first spawning season of the females, and thereafter it decreased further and remained stable at around 15%-20% for the second and third spawning season. Substitution of older females with smaller males to readjust male percentage to 50% in the fourth spawning season, was followed by sex change of larger males to females and a drop of the male percentage to 18% in the following spawning season. The present study demonstrated the long spawning season of gilthead seabream -especially under constant water temperature, the high fecundity and fertilization success, and the stabilization of male percentage to ~20% after the first spawning season or when a broodstock is modified to increase male percentage. These results are useful to the aquaculture industry, demonstrating that there is no need to add males to gilthead seabream broodstocks over the years, as the sex ratio is stabilized and egg production and fertilization success remain high with a relatively low male:female sex ratio. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish an accurate body weight (BW) prediction model for gilthead seabream Sparus aurata of 50–1000 g. Three thousand three hundred twelve (3312) fish were individually weighed and photographed. Traits measured from the images were total body length (TBL), fork body length (FBL), standard body length (SBL), body height (BH), head length (HL), eye diameter (ED), body area (BA, without fins), head area (HA), and eye area (EA). SBL, BH, BA, BA/SBL, and BA/BH showed a strong association with BW (correlation coefficients, r: 0.96–0.99). These traits were selected to proceed with the regression analysis. Simple, multiple linear, and 2nd-order polynomial regressions were applied to the whole data set and three BW subgroups of interest during gilthead seabream rearing (i.e., 50–100 g, 100–500 g, 500–1000 g). The prediction of BW from the whole data set was more accurate than from each BW subgroup. The models with the highest coefficient of determination (R2) and the lowest errors (mean absolute percentage error, MAPE) were either the power regression of BW with BA (R2: 99.0%, MAPE: 5.8%) or the multiple linear regression of BW with SBL, BA, BA/SBL, and BA/BH (R2: 98.6%, MAPE: 5.1%) as predictors. The accuracy of the two models is considered quite similar, and for reasons of simplicity, the power regression is advantageous, requiring only one trait to be measured (BA). The models identified in the present study can help to further develop the accuracy of machine vision-based systems for gilthead seabream BW measurement. [ABSTRACT FROM AUTHOR]

The transcriptome of the seabream larvae farmed in different European commercial hatcheries was analysed during critical larval stages. The complementary data herein presented support the findings reported in the associated research article “Insights into core molecular changes associated with metamorphosis in gilthead seabream larvae across diverse hatcheries”. Samples were collected from gilthead seabream (Sparus aurata) hatcheries in Greece (site Gr), Italy (site It), and France (site Fr). RNA was extracted from larvae with different weights, mainly at the flexion (23 and 25 dph) and mid-metamorphosis stages (43, 50, 52, 56, and 60 dph). RNA-seq libraries were sequenced using Illumina HiSeq xten. The paired-end sequenced raw reads were deposited in the NCBI-SRA database with the accession number PRJNA956882. Differential expression and function of genes were obtained by comparing transcriptome profiles of larvae at different developmental stages. The presented data can be used to improve marine-farmed fish larvae production during critical larval stages.

Abstract Methionine (Met) is one of the most limiting essential amino acids in aquafeeds, and different commercial feed‐grade Met sources are available for diet supplementation, namely L‐Met, DL‐Met, and hydroxy‐Met (OH‐Met). In this work, we compared the bioefficacy of OH‐Met and DL‐Met as diet supplements for gilthead seabream (Sparus aurata) juveniles reared at normal (22°C) and high (29°C) water temperatures. Two isoproteic (50%) and isolipidic (20%) practical diets (24% fish meal; 6% fish oil) were formulated to contain 1% Met and were supplemented with 0.2% DL‐Met (diet DL‐Met) or OH‐Met (diet OH‐Met). The diets were fed to triplicate groups of fish with an initial body weight of 13 g for 78 days. Growth performance and N retention (%) were higher at 29°C. However, feed efficiency, protein efficiency ratio, and hepatic and visceral indexes were higher at 22°C. Hepatic oxidative stress indicators were not affected by dietary Met source. In the muscle, however, oxidative stress index and lipid peroxidation were lower in fish fed the OH‐Met diets. Overall, DL‐Met and OH‐Met proved to be similarly effective as dietary methionine sources for gilthead seabream, while OH‐Met seemed to be more effective in reducing oxidative stress in fish reared at high temperatures.

Antimicrobial peptides (AMPs) are promising molecules in diverse fields, including aquaculture. AMPs possess lytic effects on a wide range of pathogens, resulting in a potential replacement for traditional antimicrobials in aquaculture. In addition, they also have modulatory effects on host immune responses. Thus, the objective of this work was to evaluate the immunomodulatory capability of three known synthetic AMPs derived from European sea bass, NK-lysin (Nkl), hepcidin (Hamp), and dicentracin (Dic), in head-kidney cell suspensions from European sea bass and gilthead seabream. The tested peptides were neither cytotoxic for European sea bass nor gilthead seabream cells and failed to modulate the respiratory burst and phagocytosis activities. However, they modified the pattern of transcription of immune-related genes differently in both species. Peptides were able to promote the expression of marker genes for anti-inflammatory (il10), antiviral (mx, irf3), cell-mediated cytotoxicity (nccrp1, gzmb), and antibody responses (ighm) in European sea bass, with the Nkl peptide being the most effective. Contrary to this, the effects of those peptides on gilthead seabream mainly resulted in the suppression of immune responses. To conclude, European sea bass-derived peptides can be postulated as potential tools for immunostimulation in European sea bass fish farms, but more efforts are required for their universal use in other species. [ABSTRACT FROM AUTHOR]

Methionine (Met) is one of the most limiting essential amino acids in aquafeeds, and different commercial feed‐grade Met sources are available for diet supplementation, namely L‐Met, DL‐Met, and hydroxy‐Met (OH‐Met). In this work, we compared the bioefficacy of OH‐Met and DL‐Met as diet supplements for gilthead seabream (Sparus aurata) juveniles reared at normal (22°C) and high (29°C) water temperatures. Two isoproteic (50%) and isolipidic (20%) practical diets (24% fish meal; 6% fish oil) were formulated to contain 1% Met and were supplemented with 0.2% DL‐Met (diet DL‐Met) or OH‐Met (diet OH‐Met). The diets were fed to triplicate groups of fish with an initial body weight of 13 g for 78 days. Growth performance and N retention (%) were higher at 29°C. However, feed efficiency, protein efficiency ratio, and hepatic and visceral indexes were higher at 22°C. Hepatic oxidative stress indicators were not affected by dietary Met source. In the muscle, however, oxidative stress index and lipid peroxidation were lower in fish fed the OH‐Met diets. Overall, DL‐Met and OH‐Met proved to be similarly effective as dietary methionine sources for gilthead seabream, while OH‐Met seemed to be more effective in reducing oxidative stress in fish reared at high temperatures. [ABSTRACT FROM AUTHOR]

Yeast, Saccharomyces cerevisiae, has been utilized as a probiotic in aqua-feeds to promote growth and alleviate the stress in aquatic animals. On the other hand, cadmium (Cd) toxicity causes serious retardation of growth and welfare status of aquatic animals. The present study was conducted to evaluate the protective role of dietary yeast in mitigating the waterborne Cd toxicity effects on the growth, haemato-biochemical, stress biomarkers, and histopathological investigations of gilthead seabream (Sparus aurata L.). In a 3 × 3 factorial design, the acclimated fish (20–24 g) were randomly distributed into nine treatments in triplicates where they were fed on 0.0% (control), 0.5%, and 1.0% of yeast along with exposure to 0.0, 1.0, and 2.0 mg Cd/L for 60 days. All growth parameters and mRNA expressions of IGF-1 and GH genes as well as haematological parameters were markedly increased with the increase of dietary yeast levels; meanwhile these variables were significantly retarded with Cd exposure. Contradictory effects on the above-mentioned variables were observed with Cd toxicity. In contrast, blood cortisol, glucose, total cholesterol, and triglyceride, lactate dehydrogenase, alanine transaminase, aspartate transaminase, alkaline phosphatase, in addition to DNA fragments % were noticeably increased with Cd toxicity especially at the treatment of 2.0 mg Cd/L, while decreasing with increasing dietary yeast levels. Compared with the control fish group, Cd concentrations in the gill, liver, and muscle tissues of gilthead seabream were higher in Cd-exposed treatments, especially at the treatment of 2.0 mg Cd/L. Deposition of Cd in fish liver was higher than that in gill tissues but lowest Cd residue was observed in muscle tissues. No significant changes in Cd residues in fish organs were observed in yeast-fed fish with no Cd exposure. The Cd exposure negatively affected histological status of gill, liver, and kidney tissues of S. aurata; while feeding Cd-exposed fish on yeast diets lowered the Cd residues in fish organs and recovered the adverse effects of Cd toxicity. Hence, this study recommends the addition of bakery yeast (1.0%) to fish diets to improve the performance, overall welfare, and histopathological status of gilthead seabream, S. aurata. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) and nanoplastics (NPs) are widely spread in the environment, generating significant concern due to their potential impact on environmental health. Marine species usually ingest plastic fragments, mistaking them for food. Many toxic compounds, such as plastic additives that are not chemically bound to the plastic matrix, can be released from MPs and NPs and reach humans via the food chain. This paper highlights the development and validation of a straightforward solid–liquid extraction clean-up procedure in combination with a matrix solid-phase dispersion method using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) detection, enabling facile, precise, and reliable identification and quantitation of a total of six bisphenols and phthalates in gilthead sea breams. Under the optimized conditions, the developed method showed good linearity (R2 > 0.993) for all target compounds. The recoveries obtained were between 70 and 92%. The relative standard deviations (RSDs) for reproducibility (inter-day) and repeatability (intra-day) were less than 9% and 10%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the target compounds ranged from 0.11 to 0.68 µg/kg and from 0.37 to 2.28 µg/kg, respectively. A new, efficient extraction methodology for the determination of BPA, BPS, BPF, DBP, DEP, and DHEP in gilthead seabream has been optimized and validated. [ABSTRACT FROM AUTHOR]

In vivo and in vitro treatments against Sparicotyle chrysophrii (Monogenea: Microcotylidae) parasitizing the gills of gilthead sea bream (Sparus aurata L.). Strong effect of long-term Sparicotyle chrysophrii infection on the cellular and innate immune responses of gilthead sea bream, Sparus aurata. Keywords: antiparasitics; efficacy; gilthead seabream; praziquantel; Sparicotyle chrysophrii; Sparus aurata EN antiparasitics efficacy gilthead seabream praziquantel Sparicotyle chrysophrii Sparus aurata 1439 1443 5 11/10/23 20231201 NES 231201 INTRODUCTION Praziquantel (PZQ) is a synthetic broad-spectrum antiparasitic, widely used in veterinary and human medicine (Andrews et al., [1]). [Extracted from the article]

The gilthead seabream, one of the most important species in Mediterranean aquaculture, with an increasing status of exploitation in terms of production volume and aquafarming technologies, has become an important research topic over the years. The accumulation of knowledge from several studies conducted during recent decades on their functional and biological characteristics has significantly improved their aquacultural aspects, namely their reproductive success, survival, and growth. Despite the remarkable progress in the aquaculture industry, hatchery conditions are still far from ideal, resulting in frequent abnormalities at the beginning of intensive culture, entailing significant economic losses. Those deformities are induced during the embryonic and post-embryonic periods of life, and their development is still poorly understood. In the present review, we created a comprehensive synthesis that covers the various aspects of skeletal morphogenesis and anomalies in the gilthead seabream, highlighting the genetic, environmental, and nutritional factors contributing to bone deformities and emphasized the potential of the gilthead seabream as a model organism for understanding bone morphogenesis in both aquaculture and translational biological research. This review article addresses the existing lack in the literature regarding gilthead seabream bone deformities, as there are currently no comprehensive reviews on this subject. [ABSTRACT FROM AUTHOR]

In the aquaculture industry, the transfer of lipids from the diet to fish to consumer is of great importance. Special attention is being given by researchers, feed manufactures and farmers to optimize the use of feeds to provide efficient production and the best use of dietary resources in the growth of healthy and nutritious aquaculture species. In this sense, this study was conducted to investigate the effects of dietary lipid reduction in seabream (Sparus aurata) and to assess whether reducing dietary lipid level could improve the quality of the fish without impairing their welfare. Two diets were formulated containing 20% (control) and 10% (hypolidimic) lipid levels. Fish were fed the formulated diets for nine weeks and sampling was conducted after three, six and nine weeks in order to follow the trend of the different parameters studied according to the rearing period. The results showed that the decreased dietary lipid did not significantly affect fish growth level. The total lipid content, diminished significantly by 11% and 8% after six and nine weeks, respectively, in fish fed on the lower lipid diet compared with fish fed the higher lipid level. Plasma cholesterol (CHOL) and low-density lipoprotein (LDL) were significantly reduced only after nine weeks. The total saturated fatty acid (SFA), total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) levels were significantly reduced after six and nine weeks. The oxidative state, as a biomarker welfare was investigated and the results show that catalase (CAT) and superoxide dismutase (SOD) activities and sulfhydryl proteins (PSH) and thiobarbituric acid reactive substances (TBARS) levels were not affected significantly during the study. It may be concluded that, under the experimental conditions, the decrease of dietary lipid levels from 20% to 10% could improve the fish quality without impairing fish welfare. [ABSTRACT FROM AUTHOR]

Skeletal disorders are problematic aspects for the aquaculture industry as skeletal deformities, which affect most species of farmed fish, increase production costs and affect fish welfare. Following recent findings that show the presence of osteoactive compounds in marine organisms, we evaluated the osteogenic and mineralogenic potential of commercially available microalgae strains Skeletonema costatum and Tetraselmis striata CTP4 in several fish systems. Ethanolic extracts increased extracellular matrix mineralization in gilthead seabream (Sparus aurata) bone-derived cell cultures and promoted osteoblastic differentiation in zebrafish (Danio rerio) larvae. Long-term dietary exposure to both extracts increased bone mineralization in zebrafish and upregulated the expression of genes involved in bone formation (sp7, col1a1a, oc1, and oc2), bone remodeling (acp5a), and antioxidant defenses (cat, sod1). Extracts also improved the skeletal status of zebrafish juveniles by reducing the incidence of skeletal anomalies. Our results indicate that both strains of microalgae contain osteogenic and mineralogenic compounds, and that ethanolic extracts have the potential for an application in the aquaculture sector as dietary supplements to support fish bone health. Future studies should also identify osteoactive compounds and establish whether they can be used in human health to broaden the therapeutic options for bone erosive disorders such as osteoporosis. [ABSTRACT FROM AUTHOR]

Over the years, the gilthead seabream (Sparus aurata), a prominent species in Mediterranean aquaculture with an increasing production volume and aquafarming technologies, has become an important research focus. The accumulation of knowledge via several studies during the past decades on their functional and biological characteristics has significantly improved the aquacultural aspects, namely their reproductive success, survival, and growth. Despite the remarkable progress in the aquaculture industry, hatchery conditions are still far from ideal, resulting in frequent challenges at the beginning of intensive culture, entailing significant economic losses. Given its increasing importance and the persistent challenges faced in its aquacultural practices, a thorough review is essential to consolidate knowledge, and elucidate the intricate facets concerning its distribution, life cycle, growth dynamics, genetics, aquaculture methodologies, economic dimensions, and the challenges inherent to its cultivation. [ABSTRACT FROM AUTHOR]

Water temperature variations affect fish growth and health, often leading to huge losses in fish production, especially during the cold season. To alleviate this constraint, fish farmers can use a water heating system driven by solar energy during daytime. This action will cause a water temperature drop during the night period, making it important to understand the physiological response of fish exposed to the resulting day/night temperature oscillations. To investigate this scenario, gilthead seabream juveniles (96.3 ± 1.0 g) were exposed to different thermal regimes for 67 days: Tconstant and Tdaily cycles. The latter group was exposed to daily water temperature oscillations between ~19 and 13 °C compared with a constant temperature of ~19 °C for the other experimental group. Temperature fluctuations compromised fish growth efficiency and reduced the proportion of fatty acids in several tissues, with implications for the whole proximate composition. Moreover, temperature oscillations influenced several blood parameters. These results favor the usage of a constant water temperature of ~19 °C for optimal gilthead seabream juvenile production instead of a day/night water temperature oscillating regime. Nevertheless, the type of energy used to warm the water will depend on the operational conditions and/or business strategy of fish farmers. [ABSTRACT FROM AUTHOR]

Gilthead seabream is among the most important farmed fish species in the Mediterranean Sea. Several approaches are currently applied to assure a lower impact of diseases and higher productivity, including the exploration of the fish microbiome and its manipulation as a sustainable alternative to improve aquaculture practices. Here, using 16S rRNA gene high-throughput sequencing, we explored the microbiome of farmed seabream to assess similarities and differences among microbial assemblages associated to different tissues and compare them with those in the surrounding environment. Seabream had distinct associated microbiomes according to the tissue and compared to the marine environment. The gut hosted the most diverse microbiome; different sets of dominant ASVs characterized the environmental and fish samples. The similarity between fish and environmental microbiomes was higher in seawater than sediment (up to 7.8 times), and the highest similarity (3.9%) was observed between gill and seawater, suggesting that gills are more closely interacting with the environment. We finally analyzed the potential connections occurring among microbiomes. These connections were relatively low among the host's tissues and, in particular, between the gut and the others fish-related microbiomes; other tissues, including skin and gills, were found to be the most connected microbiomes. Our results suggest that, in mariculture, seabream microbiomes reflect only partially those in their surrounding environment and that the host is the primary driver shaping the seabream microbiome. These data provide a step forward to understand the role of the microbiome in farmed fish and farming environments, useful to enhance disease control, fish health, and environmental sustainability. [ABSTRACT FROM AUTHOR]

Coastal aquaculture systems are complex environments with multiple microbial interactions that affect fish health and productivity. High-throughput amplicon sequencing is a valuable tool for identifying such bacterial communities and investigating the relationship between bacterial diversity and sustainability in these systems. In the present study, the seasonal dynamics of marine bacterial communities were assessed, in terms of diversity and composition, in three marine aquaculture farms in the northern Ionian Sea (western Greece) and a distant control site unaffected by aquaculture activities, using 16S rRNA amplicon metabarcoding. Results revealed that Proteobacteria, Bacteroidota, Cyanobacteria, and Verrucomicrobiota were the dominant phyla in the bacterial communities. Alpha diversity was significantly lower in the aquaculture farms compared to the control site. Season was the major factor driving bacterial community fluctuations. Comparative analysis between seasons revealed the presence of differentially abundant amplicon sequence variants (ASVs) in all pairwise comparisons, with the majority of them belonging to the phyla Bacteroidota (families Flavobacteriaceae, Cryomorphaceae) and Proteobacteria (family Rhodobacteraceae). Our study provides the first detailed description of bacterial communities present in Greek coastal aquaculture farms using amplicon metabarcoding analysis and expands our understanding of the impact of seasonality and environmental variables on marine bacterial community diversity and composition. [ABSTRACT FROM AUTHOR]

Lymphocystis disease is one of the main viral pathologies affecting cultured gilthead seabream (Sparus aurata) in the Mediterranean region. Recently, we have developed a DNA vaccine based on the major capsid protein (MCP) of the Lymphocystis disease virus 3 (LCDV-Sa). The immune response triggered by either LCDV-Sa infection or vaccination have been previously studied and seem to be highly related to the modulation of the inflammatory and the IFN response. However, a comprehensive evaluation of immune-related gene expression in vaccinated fish after viral infection to identify immunogenes involved in vaccine- induced protection have not been carried out to date. The present study aimed to fulfill this objective by analyzing samples of head-kidney, spleen, intestine, and caudal fin from fish using an OpenArray® platform containing targets related to the immune response of gilthead seabream. The results obtained showed an increase of deregulated genes in the hematopoietic organs between vaccinated and non-vaccinated fish. However, in the intestine and fin, the results showed the opposite trend. The global effect of fish vaccination was a significant decrease (p<0.05) of viral replication in groups of fish previously vaccinated, and the expression of the following immune genes related to viral recognition (tlr9), humoral and cellular response (rag1 and cd48), inflammation (csf1r, elam, il1β, and il6), antiviral response (isg15, mx1, mx2, mx3), cell-mediated cytotoxicity (nccrp1), and apoptosis (prf1). The exclusive modulation of the immune response provoked by the vaccination seems to control the progression of the infection in the experimentally challenged gilthead seabream. [ABSTRACT FROM AUTHOR]

A 120-day experiment investigated the new organic raw materials for Gilthead seabream (Sparus aurata) feeding on growth, nutritional parameters, digestibility, and histology. An organic control diet (CON) and three diets with 100% organic raw materials—the rest of rainbow trout, visceral Iberian pig, and insects as a protein source (TRO, IBE, and INS)—were tested. After the experiment, growth, nutritional parameters, digestibility, and histology were measured. The CON diet-fed seabream obtained the highest weight; there was no difference between the experimental diets. The crude protein content was the highest in seabream fed the TRO and INS diets. Crude fat was the highest value observed in the CON diet. High digestibility was observed in seabream-fed IBE and INS diets. Except for EAA methionine (Met), there were no static differences in retention efficiency. The diet with the highest hydrolysis rate was IBE. Diet differences were significant but had the typical healthy liver morphology of seabream. Seabream fed on the TRO and INS diets had shorter distal gut measurements. In conclusion, the full substitution of fishmeal with organic raw materials, including rainbow trout remains, Iberian pig viscera, and insects, offers several benefits in terms of digestibility, histology, and growth performance and may help improve sustainable and healthy aquaculture practices. [ABSTRACT FROM AUTHOR]

Lymphocystis disease is one of the main viral pathologies affecting cultured gilthead seabream (Sparus aurata) in the Mediterranean region. Recently, we have developed a DNA vaccine based on the major capsid protein (MCP) of the Lymphocystis disease virus 3 (LCDV-Sa). The immune response triggered by either LCDV-Sa infection or vaccination have been previously studied and seem to be highly related to the modulation of the inflammatory and the IFN response. However, a comprehensive evaluation of immune-related gene expression in vaccinated fish after viral infection to identify immunogenes involved in vaccine-induced protection have not been carried out to date. The present study aimed to fulfill this objective by analyzing samples of head-kidney, spleen, intestine, and caudal fin from fish using an OpenArray® platform containing targets related to the immune response of gilthead seabream. The results obtained showed an increase of deregulated genes in the hematopoietic organs between vaccinated and non-vaccinated fish. However, in the intestine and fin, the results showed the opposite trend. The global effect of fish vaccination was a significant decrease (p

Vibrio harveyi, a significant opportunistic marine pathogen, has been a challenge to the aquaculture industry, leading to severe economical and production losses. Phage therapy has been an auspicious approach in controlling such bacterial infections in the era of antimicrobial resistance. In this study, we isolated and fully characterized a novel strain-specific phage, vB_VhaS_MAG7, which infects V. harveyi MM46, and tested its efficacy as a therapeutic agent in challenged gilthead seabream larvae. vB_VhaS_MAG7 is a tailed bacteriophage with a double-stranded DNA of 49,315 bp. No genes linked with virulence or antibiotic resistance were harbored in the genome. The phage had a remarkably large burst size of 1393 PFU cell−1 and showed strong lytic ability in in vitro assays. When applied in phage therapy trials in challenged gilthead seabream larvae, vB_VhaS_MAG7 was capable of improving the survival of the larvae up to 20%. Due to its distinct features and safety, vB_VhaS_MAG7 is considered a suitable candidate for applied phage therapy. [ABSTRACT FROM AUTHOR]

Territoriality, spatial exploration and social hierarchy are strictly related behaviors in gregarious fishes, and are often under-appreciated in farms where the individuals are confined within crowded spaces. In this study, we investigated the role of spatial exploration, elucidating the importance of time upon forming the social organization, and the role of the territoriality in gilthead seabream (Sparus aurata), using two experimental approaches. In the first approach, three fish were placed sequentially in the aquarium with an interval of two days (sequential model), while in the second (simultaneous model), two fish were simultaneously placed in an aquarium divided by a barrier which was removed after a certain period of time. To study the effect of social stress and spatial perception in the two models, we monitored behavior (aggressive acts and feeding priority), integrated with the evaluation of physiological and cellular stress parameters, such as phagocytosis, cortisol, glucose, and blood osmolarity levels. After the establishment of the social hierarchy in the "sequential model", we observed that the levels of cortisol and an immunological cell-mediated marker were higher in subordinate individuals than in the dominant ones. We observed a different modulation of phagocytic activity in peritoneal cavity cells between dominant and subordinates, demonstrating that social stress acts upon immune response. Differently from the first model, no behavioral, physiological, or phagocytic differences were found between the two fish involved in the simultaneous model, where both fish acted as co-dominants, defending their territory. The study achieved a deeper understanding of the role of spatial exploration, territorial dominance and intraspecific interaction in gilthead seabream, and elucidated the link between them and physiological stress indicators. The results highlight aspects of interest to the aquaculture industry, showing the importance of a greater focus on rearing conditions, finding solutions to mitigate crowding effects and promoting the quality of aquacultural products. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) and nanoplastics (NPs) are widely spread in the environment, generating significant concern due to their potential impact on environmental health. Marine species usually ingest plastic fragments, mistaking them for food. Many toxic compounds, such as plastic additives that are not chemically bound to the plastic matrix, can be released from MPs and NPs and reach humans via the food chain. This paper highlights the development and validation of a straightforward solid–liquid extraction clean-up procedure in combination with a matrix solid-phase dispersion method using high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) detection, enabling facile, precise, and reliable identification and quantitation of a total of six bisphenols and phthalates in gilthead sea breams. Under the optimized conditions, the developed method showed good linearity (R2 > 0.993) for all target compounds. The recoveries obtained were between 70 and 92%. The relative standard deviations (RSDs) for reproducibility (inter-day) and repeatability (intra-day) were less than 9% and 10%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the target compounds ranged from 0.11 to 0.68 µg/kg and from 0.37 to 2.28 µg/kg, respectively. A new, efficient extraction methodology for the determination of BPA, BPS, BPF, DBP, DEP, and DHEP in gilthead seabream has been optimized and validated.

The rapid development of intensive fish farming has been associated with the spreading of infectious diseases, pathogens and parasites. One such parasite is Sparicotyle chrysophrii (Platyhelminthes: Monogenea), which commonly infects cultured gilthead seabream (Sparus aurata)—a vital species in Mediterranean aquaculture. The parasite attaches to fish gills and can cause epizootics in sea cages with relevant consequences for fish health and associated economic losses for fish farmers. In this study, a novel stratified compartmental epidemiological model of S. chrysophrii transmission was developed and analysed. The model accounts for the temporal progression of the number of juvenile and adult parasites attached to each fish, as well as the abundance of eggs and oncomiracidia. We applied the model to data collected in a seabream farm, where the fish population and the number of adult parasites attached to fish gills were closely monitored in six different cages for 10 months. The model successfully replicated the temporal dynamics of the distribution of the parasite abundance within fish hosts and simulated the effects of environmental factors, such as water temperature, on the transmission dynamics. The findings highlight the potential of modelling tools for farming management, aiding in the prevention and control of S. chrysophrii infections in Mediterranean aquaculture.

Simple Summary: The sustainability and further development of an intensive aquaculture of carnivores have been threatened in recent years by their dependence on fishmeal and fish oil. Alternative ingredients are therefore necessary to promote sustainable aquaculture production without compromising fish growth and health. Use of insects as an alternative protein source for aquaculture feed production is an excellent example of circular economy. Among insects, Hermetia illucens is one of the most promising sustainable protein and lipid sources. This study aimed to evaluate the effects of partially defatted HIM dietary inclusion on growth performance, stress indicators and gut histological traits of Sparus aurata. The feeding trial was carried out on 312 fish fed with a basal diet containing only fish meal as a protein source of animal origin, and three diets (HIM25, HIM35 and HIM50) containing 25%, 35% and 50% defatted Hermetia illucens meal as a partial replacement for fishmeal. The trial lasted 131 days. The results show that the insect meal inclusion did not affect growth performance and blood parameters and the health of the posterior gut tract, while the inclusion level at the 50% caused morphometric and histopathological changes in the anterior gut tract. Among the diets, the HIM35 was the most tolerated formulation by fish. This study provided new data and knowledge on the potential use of Hermetia illucens meal (HIM) as a new sustainable ingredient for Sparus aurata diet. The effect of HIM dietary inclusion on fish growth performance, stress indicators and gut histology was studied. For 131 days, 312 fish were fed a basal diet containing fishmeal as animal protein source, and three diets containing 25%, 35% and 50% HIM as a partial replacement for fishmeal. The main findings indicated that fishmeal can be replaced by HIM up to 110 g/kg of substitution (35% of inclusion in diet) without negative effects on growth performance, stress parameters or histological traits of the posterior gut tract, and with positive effects (p < 0.05) on the histological and morphometric characteristics of the anterior gut tract. At the same time, the results showed that the effect of Hermetia illucens meal at 50% inclusion level caused morphometric and histopathological alterations in the anterior gut tract of seabream. In conclusion, this preliminary study suggested that the dietary inclusion level of HIM35 was the most tolerated by fish showing the best gut morphometric parameters and histological conditions, with fewer signs of inflammation, as well as good nutritional and health status. [ABSTRACT FROM AUTHOR]

Simple Summary: Aquaculture is currently directing its efforts towards the principles of sustainability, especially in the reduction in the use of fishmeal, which is why it faces a constant search for alternative sources. In the current work, it has been found that the use of two different feed additives, hydrolyzed porcine mucosa and nucleotide concentrate, in different percentages in a plant-based diet for gilthead seabream, improves growth and feed efficiency. The fishmeal replacement by vegetable meals or other alternative sources, without affecting fish performance and productivity, is one of the principal challenges in aquaculture. The use of hydrolyzed porcine mucosa (HPM) and nucleotide (NT) concentrates, as feed additives in gilthead seabream (Sparus aurata L.) non-fishmeal diets was assessed in order to determine the possible effects on growth, feed efficiency, protein digestion, and gut histology when these were included in a plant-based diet (HPM 1% and 2%, P1 and P2; NT 250 and 500 ppm, N250 and N500), in comparison with two control diets, AA0 (100% plant-protein-based diet) and FM100 (100% fishmeal-protein-based diet). Diets were assayed in triplicate and the growth assay lasted 134 days. Results showed a significant improvement in all groups in terms of final weight and specific growth rate in comparison with the AA0 group. An improvement in the feed conversion ratio and the protein efficiency ratio was also observed when the additives were included in lower percentages (P1 and N250) compared to the FM100 group. Significant differences were found in hepatosomatic index, villi thickness, and goblet cells. Thus, the inclusion of NT and HPM was tested as beneficial for the improvement of efficiency of plant feed in seabream. [ABSTRACT FROM AUTHOR]

Simple Summary: This study evaluated using NGS techniques and bioinformatic analysis the influence on the microbiota and transcriptomic response of skin mechanically wounded gilthead seabream (S. aurata) specimens fed with a probiotic SpPdp11 supplemented diet. Four group of fish were established: non-wounded and wounded fed control diet, and non-wounded and wounded fed a probiotic enriched diet. The wounded group that received the probiotic diet showed a decrease in the abundance of taxa related to bacterial biofilm formation, and transcriptomic results suggested that specimens of this same group had a group of genes up-regulated and down-regulated related differently to those expressed in control group (non-wounded). Then, five genera that presented significant differences between these groups showed positive correlations with genes related to cell migration and negative correlations with inflammation and cell proliferation. These results are promising, and they open new perspectives and possibilities in the use of probiotic SpPdp11 to improve the skin after an injury, which can happen frequently in farmed specimens. Skin lesions are a frequent fact associated with intensive conditions affecting farmed fish. Knowing that the use of probiotics can improve fish skin health, SpPdp11 dietary administration has demonstrated beneficial effects for farmed fish, so its potential on the skin needs to be studied more deeply. The wounded specimens that received the diet with SpPdp11 showed a decrease in the abundance of Enterobacteriaceae, Photobacterium and Achromobacter related to bacterial biofilm formation, as well as the overexpression of genes involved in signaling mechanisms (itpr3), cell migration and differentiation (panxa, ttbk1a, smpd3, vamp5); and repression of genes related to cell proliferation (vstm4a, areg), consistent with a more efficient skin healing processes than that observed in the wounded control group. In addition, among the groups of damaged skin with different diets, Achromobacter, f_Ruminococcaceae, p_Bacteroidetes, Fluviicola and Flavobacterium genera with significant differences showed positive correlations with genes related to cell migration and negative correlations with inflammation and cell proliferation and may be the target of future studies. [ABSTRACT FROM AUTHOR]

The effects of a functional additive (Sanacore® GM; SAN) on immune and antioxidant indices, and the resistance of gilthead seabream (Sparus aurata) against Vibrio alginolyticus infection were investigated. For this, four diets containing 0% (the control), 0.1%, 0.2%, and 0.4% SAN were offered to triplicated groups of fish (20–23 g) for ten weeks. Subsequently, fish were injected intraperitoneally with V. alginolyticus and monitored for further ten days. Feeding the fish on SAN-supplemented diets showed positive effects on leukocyte counts and its differential percentages. Serum lysozyme activity and total immunoglobulin values, as well as blood phagocytic activity and indices, were linearly and quadratically higher in SAN-fed fish, especially at the 0.4% SAN diet. Similarly, linear and quadratic increases in catalase, superoxide dismutase, and total antioxidant capacity were observed in SAN-fed fish, particularly at the 0.4% SAN diet. Conversely, malondialdehyde values decreased in SAN-fed fish compared with the control group, which showed its highest value. The highest expression of the IL-1β gene coupled with the lowest TNF-α and HSP70 genes expressions was found in the fish fed with the 0.4% SAN. On the other hand, fish fed on the control diet showed the lowest IL-1β gene coupled with the highest TNF-α and HSP70 genes expressions. After bacterial infection, most of the control fish died with a relative percent of survival of 5.0%; meanwhile feeding gilthead seabream on SAN-enriched diets significantly enhanced their protection against V. alginolyticus infection fed on the 0.4% SAN diet showed 100% survival. The SAN administration to gilthead seabream especially at the 0.4% level led to significant promotions in antioxidative and immune responses and augmented the fish resistance to V. alginolyticus infection. [ABSTRACT FROM AUTHOR]

Simple Summary: The use of fishmeal and fish oil has long been an issue of major concern since nutrition for most aquaculture farms entails a considerable cost. To reduce the cost of the nutrition, many efforts have been made to replace the fishmeal/fish oil, either partially or totally, in diets by using plant-based proteins. The selected candidates per generation might be affected and the query of the establishment of a fish line selection used for a plant-based diet is under consideration. In the present study, fish were on different diets: a high-plant-protein diet containing 85% plant proteins and a high-animal-protein diet (standard commercial). During the experiment, fish were weighed and fat content was collected. We subsequently estimated the inheritance of the body weight performance and the fat content (0.39–0.85). Moreover, a genotype by diet interaction was re-evaluated causing a significant re-ranking of the selected candidates per diet. Furthermore, a higher genetic gain for body weight performance can be achieved by using the standard commercial diet, rather than the plant-based one. Thus, the establishment of a plant-based diet breeding line could be possible, if the reduction of the cost of aquafeed could balance the lower genetic gain expected to be achieved in each generation. There has been thorough research on the genotype by diet interaction and the extent of its impact on the genetic evaluation, using a partly replaced marine animal protein on the gilthead seabream. To do that, 8356 individuals were gathered from two batches and followed different diets: a high-plant-protein diet containing 85% plant proteins and a standard commercial one containing 30% marine animal protein. During the experiment, body weight, growth and fat content were recorded. High heritability estimates were detected for the body weight performance and fat content. A small effect of genotype by diet interaction was detected in all phenotypes (presented as the genetic correlations from 0.95 to 0.97) but a medium-high ranking correlation between the breeding values for each trait was estimated (0.72–0.70). A higher expected response to selection for the body weight performance was detected using the standard commercial rather than the plant-based diet. Based on the findings, the establishment of a plant-based diet breeding strategy can be achieved provided the reduction of the cost of aquafeed is attained, though a lower genetic gain is expected. [ABSTRACT FROM AUTHOR]

The present study evaluated the effects of the inclusion of commercial feed additive (Sanacore® GM; SAN) in diets on growth and productive performance, digestive enzymes, intestinal microbiota, intestinal histomorphometry and blood profile of gilthead seabream (Sparus aurata). For this purpose, four diets containing 0.0% (the control), 0.1%, 0.2% and 0.4% SAN were formulated and offered to triplicate groups of fish (20–23 g) reared in cages (30 × 10 × 3 m) for ten weeks. Water quality parameters were regularly monitored during the experimental period. No marked variations (p > 0.05) were observed in water temperature, dissolved oxygen and pH values; meanwhile, substantially decreases in unionized ammonia and nitrite levels were specifically detected at the treatment of 0.4% SAN. Feeding the fish on SAN‐supplemented diets confirmed significant modulations in fish growth and production, haemato‐biochemical profile, intestinal microbiota and intestinal histomorphometry. Fish growth, production and feed utilization indices extensively multiplied alongside with the increase in dietary SAN levels achieving their optimum values at the treatment of 0.4% SAN in contrast to the control group (0% SAN). Intestinal α‐amylase, lipase and proteases activities were notably greater in fish fed with SAN‐supplemented diets in particular at the 0.4% SAN diet. Feeding gilthead seabream on SAN‐containing diets markedly increased red blood cell counts, haemoglobin level and haematocrit per cent mainly at the diet of 0.4% SAN. Compared with the control group, highest values of serum total protein, albumin and globulin accompanied with lowest values of alanine and aspartate aminotransferase were significantly recorded in fish fed on the 0.4% SAN diet. Intestinal microbiota were additionally modulated due to SAN administration to gilthead seabream. However, marked reductions in counts of Vibrio sp. and Escherchia coli alongside with high Bacillus sp. counts were obtained in fish mid‐intestine mainly at the 0.4% diet. Feeding gilthead seabream on SAN‐enriched diets confirmed higher villi length/width, absorption area and crypt depth than the control group with optimal values at the 0.4% SAN diet. According to the outcomes observed in this study, the SAN administration to gilthead seabream, especially at the 0.4% level led to considerable enhancements in overall growth and production performance via improving the secretion of digestive enzymes and prompting the intestinal morphometry and beneficial microbiota. [ABSTRACT FROM AUTHOR]

Over the years, the gilthead seabream (Sparus aurata), a prominent species in Mediterranean aquaculture with an increasing production volume and aquafarming technologies, has become an important research focus. The accumulation of knowledge via several studies during the past decades on their functional and biological characteristics has significantly improved the aquacultural aspects, namely their reproductive success, survival, and growth. Despite the remarkable progress in the aquaculture industry, hatchery conditions are still far from ideal, resulting in frequent challenges at the beginning of intensive culture, entailing significant economic losses. Given its increasing importance and the persistent challenges faced in its aquacultural practices, a thorough review is essential to consolidate knowledge, and elucidate the intricate facets concerning its distribution, life cycle, growth dynamics, genetics, aquaculture methodologies, economic dimensions, and the challenges inherent to its cultivation.

Simple Summary: Fish provides high nutritional value in human diets but may trigger severe allergenic reactions, which result from a hypersensitive response of the immune system. Due to several allergenic proteins, and especially to parvalbumin, consumers with a known fish allergy must avoid any product that might contain this protein. This study focused on the characterization of parvalbumin in gilthead seabream and European seabass. Using mass spectrometry and circular dichroism, parvalbumins primary (sequence) and secondary structures were determined, respectively. Furthermore, parvalbumin was detected by sandwich enzyme-linked immunosorbent assay after gastrointestinal digestion and fish processing techniques. Parvalbumin—presented as α-helices and β-sheets, at room temperature—was detected at lower levels during gastrointestinal digestion. Several processing techniques showed a significant reduction (p < 0.05) in parvalbumin detectability, in comparison to raw muscle samples from gilthead seabream and European seabass. Therefore, we concluded that parvalbumins from both species are susceptible to digestion and processing. These results demonstrate that these techniques can be used in parvalbumin modulation and may be an important contribution to further studies on fish allergenicity. Consumption of aquatic food, including fish, accounts for 17% of animal protein intake. However, fish consumption might also result in several side-effects such as sneezing, swelling and anaphylaxis in sensitized consumers. Fish allergy is an immune reaction to allergenic proteins in the fish muscle, for instance parvalbumin (PV), considered the major fish allergen. In this study, we characterize PV in two economically important fish species for southern European aquaculture, namely gilthead seabream and European seabass, to understand its stability during in vitro digestion and fish processing. This information is crucial for future studies on the allergenicity of processed fish products. PVs were extracted from fish muscles, identified by mass spectrometry (MS), and detected by sandwich enzyme-linked immunosorbent assay (ELISA) after simulated digestion and various food processing treatments. Secondary structures were determined by circular dichroism (CD) after purification by anion exchange and gel filtration chromatography. In both species, PVs presented as α-helical and β-sheet structures, at room temperature, were shown to unfold at boiling temperatures. In European seabass, PV detectability decreased during the simulated digestion and after 240 min (intestinal phase) no detection was observed, while steaming showed a decrease (p < 0.05) in PVs detectability in comparison to raw muscle samples, for both species. Additionally, freezing (−20 °C) for up to 12 months continued to reduce the detectability of PV in tested processing techniques. We concluded that PVs from both species are susceptible to digestion and processing techniques such as steaming and freezing. Our study obtained preliminary results for further research on the allergenic potential of PV after digestion and processing. [ABSTRACT FROM AUTHOR]

Water temperature variations affect fish growth and health, often leading to huge losses in fish production, especially during the cold season. To alleviate this constraint, fish farmers can use a water heating system driven by solar energy during daytime. This action will cause a water temperature drop during the night period, making it important to understand the physiological response of fish exposed to the resulting day/night temperature oscillations. To investigate this scenario, gilthead seabream juveniles (96.3 ± 1.0 g) were exposed to different thermal regimes for 67 days: Tconstant and Tdaily cycles. The latter group was exposed to daily water temperature oscillations between ~19 and 13 °C compared with a constant temperature of ~19 °C for the other experimental group. Temperature fluctuations compromised fish growth efficiency and reduced the proportion of fatty acids in several tissues, with implications for the whole proximate composition. Moreover, temperature oscillations influenced several blood parameters. These results favor the usage of a constant water temperature of ~19 °C for optimal gilthead seabream juvenile production instead of a day/night water temperature oscillating regime. Nevertheless, the type of energy used to warm the water will depend on the operational conditions and/or business strategy of fish farmers.

The primary source of persistent organic pollutant (POP) exposure is food, especially fish. European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata) are among the most eaten sea fish in Italy. Fish from lakes in Northern Italy, such as agone (Alosa agone), represent niche consumption for most people, but possibly constitute a much larger percentage of overall consumption volume for local residents. This study dealt with the presence of POPs in the above-mentioned fish species via GC-MS/MS analysis. None of the analytes for which maximum limits are in place showed concentrations above those limits. Moreover, none of the substances without maximum limits exceeded the provisional tolerable daily intake (PTDI) when given, nor did they exceed the more general values considered safe, even for 99th percentile consumers. [ABSTRACT FROM AUTHOR]

Simple Summary: Aquaculture plays an important role in supplying global food demand and protein sources. The increasing restriction of drugs in fish production has forced this sector to carry out changes in the management of farms. Functional feed additives such as probiotics, prebiotics, and phytogenics have been proposed in order to maintain or improve productive levels and general health status of fish. In this study, we explore the effects of Allium-derived food additives in the bacterial community and growth of gilthead seabream (Sparus aurata) juveniles. We found that this additive produced significant changes in bacterial community of the hindgut. In this sense, this shift occurred towards a more diverse microbiota. Especially relevant is the decrease in the populations of potential pathogenic bacteria as Vibrio and Pseudomonas, while this additive enhanced Lactobacillus, a well-known beneficial genus. Our work shows that the addition of PTSO has beneficial effects on bacterial communities while keeping productive parameters on fish growth. This study analyzes the potential use of an Allium-derived compound, propyl propane thiosulfonate (PTSO), as a functional feed additive in aquaculture. Gilthead seabream (Sparus aurata) juveniles had their diet supplemented with this Allium-derived compound (150 mg/kg of PTSO) and were compared with control fish. The effects of this organosulfur compound were tested by measuring the body weight and analyzing the gut microbiota after 12 weeks. The relative abundance of potentially pathogenic Vibrio and Pseudomonas in the foregut and hindgut of supplemented fish significantly decreased, while potentially beneficial Lactobacillus increased compared to in the control fish. Shannon's alpha diversity index significantly increased in both gut regions of fish fed with a PTSO-supplemented diet. Regarding beta diversity, significant differences between treatments only appeared in the hindgut when minority ASVs were taken into account. No differences occurred in body weight during the experiment. These results indicate that supplementing the diet with Allium-derived PTSO produced beneficial changes in the intestinal microbiota while maintaining the productive parameters of gilthead seabream juveniles. [ABSTRACT FROM AUTHOR]

Due to the emergence of multidrug-resistant bacteria, commonly known as "superbugs", phage therapy for the control of bacterial diseases rose in popularity. In this context, the use of phages for the management of many important bacterial diseases in the aquaculture environment is auspicious. Vibrio harveyi, a well-known and serious bacterial pathogen, is responsible for many disease outbreaks in aquaculture, resulting in huge economic and production losses. We isolated and fully characterized a novel bacteriophage, Vibrio phage Virtus, infecting V. harveyi strain VH2. Vibrio phage Virtus can infect a wide spectrum of Vibrio spp., including strains of V. harveyi, V. owensii, V. campbellii, V. parahaemolyticus, and V. mediterranei. It has a latent period of 40 min with an unusually high burst size of 3200 PFU/cell. Vibrio phage Virtus has a double-stranded DNA of 82,960 base pairs with 127 predicted open reading frames (ORFs). No virulence, antibiotic resistance, or integrase-encoding genes were detected. In vivo phage therapy trials in gilthead seabream, Sparus aurata, larvae demonstrated that Vibrio phage Virtus was able to significantly improve the survival of larvae for five days at a multiplicity of infection (MOI) of 10, which suggests that it can be an excellent candidate for phage therapy. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the effects on growth performance, intermediary metabolism and welfare of the inclusion of two commercial microalgae-based ingredients called LB-ChromaBream (LB-CB) and LB-ChromaBream-plus (LB-CBplus) in the diet of gilthead seabream (Sparus aurata) close to commercial size. For this purpose, fish of ~182 g of initial body mass were fed to satiety (ad libitum) for 41 days with three different diets: (i) CONTROL diet (CTRL), with a commercial-like formulation; (ii) LB-CB diet, with a 10 % inclusion of microalgal product; (iii) LB-CBplus diet, with a 10 % inclusion of the same product but enzymatically hydrolysed to increase the bioavailability of the nutrients. The results obtained show that the use of these microalgal products leads an overall improvement in productive parameters in terms of growth (15 % in SGR) and feed efficiency (11 %), as well as a significant reduction in circulating cortisol with the LB-CBplus diet. Observations on plasma and liver metabolites, and particularly on hepatic metabolic enzymes, collectively indicate that microalgae supplementation of feed lead to a better use of carbohydrates as a source of energy in the liver and other tissues, potentially sparing triglycerides within this tissue, and a channelling hepatic triglycerides to fuels growth. Finally, the specimens fed the supplemented diets experienced a substantial improvement in intestinal health, achieved by longer intestines, a higher transepithelial resistance and better apparent permeability measured by electrophysiological methods, especially those fed LB-CBplus, which could explain the increase in productive performance by improving nutrient assimilation. In conclusion, this study shows that the experimental feeds, especially the one containing biotechnologically treated microalgae, are suitable for improving some important indicators of growth performance and physiological condition of gilthead seabream, thus revealing the potential for their inclusion in new functional feeds for this species at an advanced stage of the production cycle.

Peracetic acid (PAA) is a European Union Commission authorized disinfectant for use in animal health care. It has shown a strong inactivation potential for bacteria, viruses, fungi and bacterial spores. A stress-related adaptive response after an exposure to PAA has been described in different species of fish such as carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss). The present study aims to evaluate the response of gilthead seabream systemic (plasma) as mucosal (gill and skin) defences after PAA a unique exposure (5 min), by measuring cortisol, glucose and lactate in plasma, as well as the expression of several genes (glutathione peroxidase, glucocorticoid receptor, superoxide dismutase 2 and superoxide dismutase involved in the response to oxidative stress in mucosal tissues). study. We observe how seabream (Sparus aurata) copes with oxidative stress induced by PAA. PAA exposure did not induce an important antioxidant response in fish, whereas induced a mild response to stress, with a fast and effective recovery of basal levels after 24 h. Although PAA triggers a mild stress response, the response described in our study reflect that it can be used for sea bream in the concentration tested with no severe physiological consequences.

Knowledge of population structure and genetic diversity within and between wild and farmed populations of gilthead sea bream (Sparus aurata) and European seabass (Dicentrarchus labrax) is important to achieve sustainable aquaculture production of these species and to assess the risk of genetic impacts of fish escaped from farms. Previous population genetic studies on these species have been based on a limited number of genetic markers and samples. In this study, these features were assessed using samples from 24 seabream and 25 seabass populations distributed throughout the Mediterranean Sea, and 3 wild seabream Atlantic populations. Samples were genotyped with a newly developed combined species SNP array that includes ~60K SNPs. Data from sequencing pools of individual DNA from the same populations were also used. Different approaches were employed for identifying the extent of population stratification within species. The effective population size (a parameter inversely related to the rate at which genetic variability is lost) was estimated for each population based on linkage disequilibrium. Population structure results revealed a clear differentiation between wild and farmed populations in both species. Wild populations showed a low degree of differentiation, particularly in seabream. Despite this, a slight differentiation was observed between Atlantic and Mediterranean seabream populations and between western and eastern Mediterranean seabass populations. However, farmed populations were quite heterogeneous and showed a high degree of differentiation. Some farmed populations of both species showed a genetic makeup similar to that found in wild populations. In general, the effective population size was large (> 1000) for wild and small (< 100) for farmed populations of both species. About 40% of the seabream and 80% of the seabass farmed populations had estimates of effective population size smaller than 50 highlighting the need of applying measures to control the rate at which genetic variability is lost.