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This study was undertaken to assess the effects of dietary sodium propionate (SP) supplementation on the growth, haemato-immunological parameters, gut microbiota, and intestinal histology of European seabass (Dicentrarchus labrax) fry. In total, four diets were evaluated during a 90-day growth trial: a control (CTRL) diet without SP supplementation and three diets including 0.1%, 0.2%, or 0.3% SP, which were called SP1, SP2, and SP3, respectively. Diets were assigned to seabass (initial body weight: 0.45 ± 0.23 g), and the results revealed a 34%, 19%, and 15.6% increase in weight gain in SP3-, SP2-, and SP1-fed fish, respectively, concomitant with a lower feed conversion ratio in these fish than in fish not receiving the supplement (CTRL), which exhibited the lowest performance among all fish groups. Administration of 0.3% or 0.2% SP elevated the carcass protein content, major blood constituents, and immune function indicators compared to the CTRL. In addition, dietary inclusion of SP positively modified the bacterial community composition in the distal intestine (DI) of fish, causing an approximately 95% and 87% reduction in total microbial count in SP3- and SP2-fed fish, respectively, compared to CTRL fish. Vibrio spp. were non-existent (zero or negligible) in fish fed the SP2 and SP3 diets, and the number of faecal coliform bacteria gradually decreased to zero in SP3-fed fish. Additionally, an improvement in fish intestinal features, particularly in the DI, was evident from measurements of histological sections from the proximal, mid, and distal intestine. The greater villus area (height and width) and goblet cell count in fish fed the SP3 or SP2 diet than in fish not receiving the supplement suggested stimulation of digestive secretions with enhanced mucus production. In conclusion, enrichment of the diet with either 0.3% or 0.2% SP is capable of improving seabass fry growth performance, general health status, immune response efficiency, and intestinal function.

An innovative physicochemical approach for treating the recycled water within a seawater recirculating aquaculture systems (RAS) has been recently developed, which includes inherent disinfection within the ammonia electro-oxidation cycle. The efficiency of the inherent disinfection was tested in comparison to a RAS consisting of a bio-treatment unit (which did not include a disinfection component), both systems operating under similar fish densities and makeup water flow rates. Neural necrosis virus (NNV) was chosen as a model pathogen, due to its pathogenicity to sea bass (Dicentrarchus labrax) and many other aquaculture species. The course of infection (exposure → immune response → infection) was monitored in a cohabitation experiment, testing the horizontal transmission of NNV using immunological and molecular methods, in addition to recording clinical signs. Results indicate that under the conditions prevailing in the RAS in which the physicochemical method was applied, the NNV horizontal transmission pathway was blocked. No immune response to viral neural necrosis (VNN) was detected in the fish sampled during the experiment, in contrast to a significant and classic immune response observed in the fish held in the RAS based on bio-treatment. Challenged fish in both systems showed typical outbreak profile, however in the bio-treated RAS, a slow disease course was observed, hypothesized by us to be the result of a high concentration of humic substances present in the water. The results indicated that the off-host phase of the NNV can be controlled by effective chlorine-based disinfection. The disinfection effect in the physico-chemically-treated RAS and C∙t (chlorine concentration times the retention time) value quantified in the present work are most likely sufficient to reduce infection of a wide range of other aquaculture pathogens.

Fishmeal (FM) possesses one of the highest buffering capacities in comparison to most alternative vegetable aquafeed ingredients and its decreasing content in current formulations might affect the ideal gastrointestinal environment for digestive enzyme action and gut bacterial community of carnivorous fish species. A study was undertaken, therefore, to assess growth response, gastrointestinal pH, digestive enzyme activity and gut bacterial community of European sea bass (Dicentrarchus labrax L.) juveniles fed low FM diets (10% FM) with or without a feed buffering additive, calcium carbonate (FM10 + B and FM10, respectively) in comparison to a standard FM diet (20% FM, FM20). Three isonitrogenous and isolipidic extruded diets were fed to triplicate fish groups of 80 individuals (initial weight: 23 g) to overfeeding over 64 days. No significant differences due to low FM dietary levels were observed in final body weight, specific growth rate, feed intake, feed and protein efficiency. Low FM diet did not affect gastrointestinal pH in the stomach, anterior intestine, mid-intestine and hindgut at 0, 4, 8 and 12 hours post meal (hpm) while the inclusion of calcium carbonate in low FM diet seems to slightly increase the pH in the hindgut at 12 hpm. The absence of significant differences of pepsin, chymotrypsin, amylase and lipase activity suggests a comparable digestive efficiency among treatments although trypsin activity was slightly reduced in low FM diets after 4 hpm. Decreasing FM content seems to exert an effect on the overall gut bacterial community analysed by next-generation sequencing even if no significant effects on specific bacterial component were detected. The gut bacterial community in all the treatments was particularly rich in lactic acid bacteria such as Lactobacillus spp. which may provide important beneficial functions for the host and be associated with a healthy intestinal epithelium. According to the results, increasing the feed buffering capacity does not seem to improve digestive conditions while it is feasible to include 10% FM dietary level in practical formulation for European sea bass juveniles without negatively affecting growth, feed efficiency and digestive luminal conditions. info:eu-repo/semantics/publishedVersion

Special issue Innovations throughout the supply chain.-- 17 pages, 2 figures, 7 tables, supplemental material https://doi.org/10.1080/13657305.2019.1632388, Often, increases in farmed seabass and seabream production surpluses from Turkey and Greece have been blamed to lead to price declines and aquaculture sector crises. In this study, we investigate whether Turkish exports of farmed European seabass affect prices of European Union (EU) farmed European seabass. This is done by examining the existence of market integration between the prices of Turkish exports of farmed European seabass into the EU and the prices of farmed European seabass commercialized in wholesale markets in Barcelona, Madrid and Paris. Market integration and competition studies in fisheries and aquaculture products have generally focused on analyzing substitutability between species and between wild and farmed conspecifics. Few studies have focused on analyzing market integration between different geographic areas. Market integration analyses between different geographic areas have proven useful in anti-dumping investigations. Results show the lack of market integration between EU imports of Turkish farmed European seabass and main EU wholesale markets; in other words, farmed European seabass prices in EU markets do not seem to be affected by export prices of Turkish farmed seabass

Mycobacteriosis is a chronic progressive disease affecting teleost fishes all over the world. No vaccine is commercially available against its main etiological agent, Mycobacterium marinum. The mycobacterial gene responsible for invasion and intracellular persistence, iipA, is known to modulate M. marinum pathology. The innate and adaptive immune responses in sea bass (Dicentrarchus labrax) vaccinated with M. marinum iipA::kan mutant with (and without) the use of adjuvant, with (and without) a booster vaccination were monitored. The adjuvanted vaccine induced enhanced immune responses. TNF-α transcription levels were extremely high in spleen of the fish vaccinated with the addition of adjuvant in both fish vaccinated once and twice, followed by an IgM response highly specific for M. marinum. Also, histologically, granulomas started appearing in spleen and head-kidney tissues (but with no visible bacteria) within a month after vaccination, mainly with the adjuvanted vaccine. This was followed by reduction in pathology, as demonstrated by the lower number of granulomas (with visible bacteria), indicating that even heat-killed bacteria were able to elicit granulomatous formations. Adhesion of the internal organs and moderate pigmentation were observed in the perivisceral adipose tissue of nearly all vaccinated fish. Although the adjuvanted heat-killed avirulent iipA::kan mutant clearly induced a strong humoral and adaptive immune response, the booster treatment did not seem to have produced a significantly higher degree of protection from the disease compared to fish that received a single vaccination.

We assessed the effects of light intensity and spectrum on the growth, development and survival of Dicentrarchus labrax larvae from 30 to 96 days after hatching. Twelve lighting regimes were applied using 0.3, 1 and 2 W/m² full spectrum white, blue, red and green light. By day 66 of exposure, growth performance was significantly better in larvae reared under green or red light compared with white or blue light (p

The inclusion of phytogenics in fish feed is a promising strategy to compensate for the negative performance effects of replacing fishmeal (FM) with vegetable sources. The present work assessed the interactive effects of different dietary FM levels (22.5 and 10% of formulation) and the supplementation of a commercial blend of anise, citrus, and oregano essential oils (Digestarom PEP M.G.E 150) on European sea bass, Dicentrarchus labrax growth performance, nutrient utilization, gut morphology, antioxidant status, and immunological response over a 60‐day growth trial. Results showed decreased growth and protein efficiency ratio and increased feed conversion ratio with a low dietary FM level. In contrast, supplementation of the phytogenic product demonstrated improved performance and nutrient utilization together with increased protein and energy retention. Supplementation with the plant essential oils fully compensated for the negative intestinal changes observed in sea bass fed a low‐FM diet but showed little improvement in fish immunological response, except for the 30% increase in lysozyme activity observed in fish fed the low FM‐supplemented diet compared to those fed the standard high‐FM diet. Overall, this study supports the use of this phytogenic product in low‐FM diets as a possible tool to decrease feed costs associated with FM without compromising fish performance, nutrient utilization, and health.

Nucleotides, nucleosides and nucleic acids (NU) have many critical functions in supporting life and increasing evidence suggests that exogenous supply can benefit the health of mammals and fish. For these reasons, a 6‐week feeding trial was conducted on juvenile European seabass (Dicentrarchus labrax) with diets containing 0%, 0.15% and 0.3% inclusion of a NU mixture (Laltide®) derived from the yeast Saccharomyces cerevisiae. At the end of the study no significant differences were found in fish performance, although a tendency towards better performance was indicated in fish fed the Nu0.3 diet. In relation to histological assessment, a significantly greater perimeter ratio; internal to outer (IP/OP) was observed in the posterior intestine of fish fed supplemental NU. Microvilli heights in the posterior intestine were also shown to be significantly promoted in fish fed NU diets (p 0.05). Overall, this study indicates that orally administered NU may be effective promoters of gut functional topography with marginal associated improvements to fish performance. Nonetheless, longer exposure and/or commercial scale application, and in diets that were challenging in use of high inclusion levels of plant by‐products would potentially amplify improvements in production characteristics, in turn benefiting fish culturists.

In aquaculture, there is high interest in substituting marine-derived with vegetable-based ingredients as energy source. Farmed carnivorous fish under high carbohydrate diets tend to increase adiposity but it remains unclear if this happens by increased lipid retention/accumulation, promotion of lipogenic pathways, or both. In order to determine the response of extrahepatic tissue to dietary starch, European (Dicentrarchus labrax) and Asian (Lates calcarifer) seabass were fed a control (low starch; LS) or experimental (high starch; HS) diet, for at least 21 days and then transferred for 6 days to saltwater enriched with deuterated water 2H2O. Incorporation of 2H-labelling follows well-defined metabolic steps, and analysis of triacylglycerols (TAG) 2H-enrichment by 2HNMR allowed evaluation of de novo lipogenesis (DNL) in muscle and visceral adipose tissue (VAT). Fractional synthetic rates for TAG-bound fatty acids and glycerol were quantified separately providing a detailed lipogenic profile. The FA profile differed substantially between muscle and VAT in both species, but their lipogenic fluxes revealed even greater differences. In European seabass, HS promoted DNL of TAG-bound FA, in muscle and VAT. High 2H-enrichment also found in muscle TAG-bound glycerol was indicative of its role on lipid cycling. In Asian seabass, HS had no effect on muscle FA composition and lipogenic flux, with no 2H-enriched TAG being detected. VAT on the other hand revealed a strong enhancement of DNL in HS-fed fish along with high TAG-bound glycerol cycling. This study consolidated the use of 2H2O as tracer for fish lipid metabolism in different tissues, under different dietary conditions and suitable to use in different fish models.

The European seabass (Dicentrarchus labrax) is a teleost remarkably adapted to a wide range of water salinity, through osmoregulatory mechanisms, mainly operating in the gills and the intestine. As an important aquaculture species, its rearing in low-salinity conditions offers benefits for its inland culture. However, this demands a full comprehension of the European seabass osmoregulatory mechanisms and its response to acclimation protocols. The purpose of this study was to evaluate different acclimation protocols in terms of osmoregularity and stress response, following transferring of European seabass juveniles from seawater to freshwater. In addition, nutrient absorption was also examined since drinking rates are sensitive to salinity. The acclimation challenge was applied through three protocols: direct transfer (0 h) to freshwater, gradual transfer during 3 h and during 72 h. The short- (1 h after complete change to freshwater) and long-term effects (after 2 months) of each acclimation protocol were evaluated by assessing the expression of 1. The osmoregulatory genes: Na+/K+-ATPase α1, Na+/K+/2Cl− 1 co-transporter, aquaporins 1 and 3, and the cystic fibrosis transmembrane conductance regulator; 2. The heat shock protein 70 gene; 3. The peptide transporter genes corresponding to PepT1a, PepT1b and PepT2. The short-term acclimation response was pronounced in both gills and the intestine affecting stress-, osmoregulatory- and nutrient-related gene expression. Long-term effects were only evident in the intestine. Direct transfer in freshwater mainly induced a long-term stress response, while the short-term effect was more pronounced in the 3 h-transfer, potentially due to handling. Our results suggest that although the European seabass can withstand direct transfer to low-salinity conditions, a gradual transfer is recommended to prevent long-term stress effects.

Tryptophan participates on several physiological mechanisms of the neuroendocrine-immune network and plays a critical role in macrophages and lymphocytes function. This study intended to evaluate the modulatory effects of dietary tryptophan on the European seabass (Dicentrarchus labrax) immune status, inflammatory response and disease resistance to Photobacterium damselae piscicida. A tryptophan deficient diet (NTRP); a control diet (CTRL); and two other diets supplemented with tryptophan at 0.13% (TRP13) and 0.17% (TRP17) of feed weight were formulated. Fish were sampled at 2 and 4 weeks of feeding and the remaining were i.p. injected with Phdp (3 × 106 cfu/fish) at 4 weeks and the inflammatory response (at 4, 24, 48 and 72 hours post-infection) as well as survival were evaluated. Results suggest that fish immune status was not altered in a tryptophan deficient scenario whereas in response to an inflammatory insult, plasma cortisol levels increased and the immune cell response was compromised, which translated in a lower disease resistance. When dietary tryptophan was offered 30% above its requirement level, plasma cortisol increased and, in response to bacterial infection, a decrease in lymphocytes, monocytes/macrophages and several immune-related genes was observed, also compromising at some degree fish disease resistance. This work was partially supported by Projects ALISSA (reference ALG-01-0247-FEDER-3520), IF/00197/2015 and INFLAMMAA (reference 02/SAICT/2017/032349), financed by Portugal and the European Union through FEDER, COMPETE 2020 and CRESC Algarve 2020, in the framework of Portugal 2020, and through the COMPETE and Operational Human Potential Programmes and national funds through Fundação para a Ciência e a Tecnologia (FCT, Portugal). M. Machado and B. Costas were supported by FCT, Portugal (SFRH/ BD/108243/2015 and IF/00197/2015, respectively). The authors also acknowledge Dr. Nuno Santos (i3S/IBMC) for critically reviewing the manuscript.

High protein distiller's dried grains (HP‐DDG) are co‐products of ethanol production that uses prefractionation technology. An 8‐week growth trial was conducted to investigate the effect of partial replacement of soybean meal (SBM) by three levels of HP‐DDG (30%, 40% and 50%) on growth performance, physiological parameters and histological changes of the intestine of European sea bass, Dicentrarchus labrax. The results indicated that an increased dietary level of HP‐DDG of more than 30% significantly increases growth performance and improved the FCR of sea bass. In addition, replacement of SBM by HP‐DDG enhanced feed intake efficiency and the health status of fish. Haematology and serum biochemistry (haemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs), packed cell volume (PCV %) and humeral immune parameters including total protein, albumin, globulin, cholesterol, lysozyme activity and total antioxidant capacity significantly increased with increase HP‐DDG inclusion levels. The findings of this study indicated that HP‐DDG is a good complementary protein source for inclusion aquaculture diets and levels above 30% as a replacement of SBM did not compromise growth performance and physiological parameters of sea bass while enhancing some important indices of health status in this species.

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.

In the present study, a multi-class multi-residue method for the simultaneous detection and determination of antibiotics in European sea bass (Dicentrarchus labrax) was developed and validated. The method based on UHPLC-MS/MS proved to be a rapid, highly selective and sensitive tool, requiring minimum sample preparation, for screening and detection of 47 compounds from eight different classes. The validation was performed according to EU regulation 2002/657/EC, proving the method's suitability for application in routine analysis. The method was applied to the analysis of 30 samples of farmed European sea bass purchased in different supermarkets in Portugal. Antibacterial residues were detected in 6 of the 30 analysed samples, namely enrofloxacin and oxytetracycline, in concentrations ranging from 0.1 to 12 µg kg

The paper aims to give a comprehensive descriptive survey on the production of Lake Bardawil from 1985 to 2015. The average production in this period was 2970 tons. Monthly samples were collected for 12 species of fish during fishing season 2015. The results showed that the Length at first capture (Lc) of different species in Bardawil Lagoon was less than the length at first maturity (Lm); Lm of Mugil cephalus, Sparus aurata and Dicentrarchus labrax was 31.1, 24.5 and 31.0 cm, meanwhile, Lc was 29.0, 18.5 and 27.8 cm respectively. The percentage of small fish with less than the Length at first maturity (Lm) constitutes 67.3% for inexpensive species and 77.05% for expensive species. The loss of biomass in the inexpensive species was estimated at 3268 tons and the loss in income was 199 million Egyptian pounds (LE). The loss of biomass of expensive species was calculated at 1455 tons and the loss of income was 175 million LE. The total loss of biomass was 4723 tons and 374 million LE due to fishing violations and the use of illegal nets in only one fishing season. For proper management, the Length at first capture (Lc) must be increased by widening the nets mesh size. Legal fishing methods and the development of appropriate non-traditional methods for the management of Bardawil Lagoon must be applied. Keywords: Bardawil Lagoon, Egypt, Lm, Lc, Biomass, Income, Bycatch

The distribution of twenty-four metals and elements in the tissues and organs of brood stock European seabass (Dicentrarchus labrax) was investigated. Muscle, liver, kidney, gills, bone, scales, gonads, otoliths and stomach were dissected from seabass brood stock from hatcheries in different sites in Greece, Eastern Mediterranean. The tissues and organs were clearly different depending on their metal and element content, except for bone and scales. The concentrations of most metals and elements were higher in the liver, kidney, bone and scales compared to the other body tissues and organs. Liver and kidney are the main detoxifying tissues of fish. Bone and scales accumulate the essential elements for the physiological function of the organisms. Muscle and otoliths accumulated the lowest concentrations of most metals and elements compared to the other tissues due to their low metabolic activity. However, the content of a few metals and elements was higher in gills, scales and stomach. Thus, it seems that the accumulation of metals and elements is tissue/ organ-specific and depends mainly on the biological role and activity of each tissue and the exposure pathway as well as on the chemistry of each element.

The aquaculture industry is currently looking for alternative, sustainable diets that provide similar or better growth for the reared species. We investigated whether replacing fishmeal with yellow mealworm (Tenebrio molitor) meal in the supplied diets of the gilthead sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax) and rainbow trout (Oncorhynchus mykiss) causes similar shifts in the bacterial gut communities of these farmed fish species. The diversity of the gut bacterial 16S rRNA gene revealed the presence of 598 operational taxonomic units (OTUs) belonging to all of the major phyla known to exist in the gut of these three fish species, such as Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. Although no statistically significant differences of diversity indices in all three species was found, there was a differential shift in the dominant bacteria in the gut of each species before and after the dietary meal replacement. In S. aurata and D. labrax diversity indices remained practically unchanged before and after the replacement, while for O. mykiss the five-fold increase of the Simpson dominance D index and the almost two-fold decrease of the Shannon H index, suggested that a more specialized gut bacterial community was favoured for this species after the replacement. Also, this replacement resulted in the occurrence of higher number of OTUs which were absent before the replacement in the gut of S. aurata (62.2% of all its OTUs) and D. labrax (60.0% of all its OTUs) compared to O. mykiss (33.0% of all its OTUs) suggesting that insect meal replacement resulted in novel nutritional niches in the gut of S. aurata and D. labrax compared to O. mykiss. Our results indicate that the most desirable fish diet substitution differentially affects the gut microbiota in different hosts, implying that a species-specific tailor-made approach in diet manipulations should be considered in the future.

The present study was conducted to evaluate the effect of various dietary levels of high protein distiller’s dried grains (HPDDG) supplemented with enzyme phytase on growth performance, feed utilization and haematological indices of European sea bass Dicentrarchus labrax fingerlings. A total of 150 D. labrax fingerlings with an average body weight of 7.5 ± 0.5g were divided in the five experimental treatments (in triplicates each). The experiment was conducted for 56 days. Fish were fed to apparent the satiation six days a week. Five isonitrogenous 45% CP experimental diets were formulated. The control (C) diet had no high protein distiller’s dried grains (HPDDG) and phytase enzyme added. Diet 2 (C+) was formulated as control diet and supplemented with phytase at a level of 0.5 g/kg. Diets 3-5 each contained HPDDG at levels of 20, 30, and 40 %, respectively with soybean meal and supplemented each with phytase at a level of 0.5 g/kg. Over the 56 days feeding period, all fish fed HPDDG-supplemented with phytase diets resulted in higher growth than the control diet, suggesting that the using of HPDDG-supplemented with phytase enhanced the growth performance of sea bass fingerlings. The same trend was recorded for the best FCR and PER. The hematology and serum biochemistry (hemoglobin (Hb), red blood cells (RBCs) count, white blood cells (WBCs) and hematocrit (Hct %) and immune parameters (total protein, albumin, globulin, cholestorl, lysozyme activity and total antioxidant capacity) of D. labrax fingerlings significantly (P ≥ 0.05) increased with increasing dietary HPDDG with phytase. Result indicates that HPDDG with phytase is a good alternative protein source for compromising growth performance and physiological parameters of European sea bass, Dicentrarchus labrax Fingerlings

Rendered fats can be sustainable alternatives to fish oil due to their lower price and wider availability. This study evaluates the effects of replacing fish oil by increasing levels of poultry fat (PF) on the nutrient utilization, growth performance, tissue composition and lipid metabolism of European seabass (Dicentrarchus labrax) juveniles. Homogeneous groups of 20 fish (19.1 ± 2.6 g) were subjected to a 12-h light/12-h dark photoperiod regime and kept in a recirculating saltwater system (salinity 35‰, 21 ± 1 °C) for 16 weeks. Triplicate groups of fish were fed a commercial-based diet as control (FO) and four isonitrogenous experimental diets, with 25 (25PF), 50 (50PF), 75 (75PF) and 100% (100PF) fish oil replacement. Soy lecithin was also tested in the diet with 100% PF (100PFL) as an emulsifier agent. The inclusion of PF did not affect nutrient's digestibility nor plasma metabolites at 24 h post-feeding. Final body weight (62–67 g), feed intake, feed conversion ratio, protein efficiency ratio and whole-body composition were similar among experimental diets. Selected lipogenic enzymes' activities were similar among FO and PF diets. The fatty acids profile of muscle, liver and heart reflected the dietary lipid source, decreasing PUFA and increasing MUFA contents with PF inclusion. Fish fed 25PF and 50PF were still able to provide the EPA and DHA muscle levels recommended for human consumption, but 100PF resulted in increased liver lipid accumulation and reduced muscle omega-3 levels. Including soy lecithin could significantly attenuate liver lipid content in fish fed PF-based diets.

With high Aw, rich nutrients and suitable pH, aquatic products are generally perishable. It becomes a pivotal restriction in fishing and aquaculture industry. Aimed to this, a novel superchilling storage-ice glazing (SS-IG) approach with clove essential oil (EO) was established in this study. EO was obtained from dry clove buds. Its major components (99.26%) were identified using gas chromatography–mass spectrometry (GC–MS) analysis. Its antioxidant activity was revealed by DPPS (IC50 = 23.39 μg/mL) and ABTS (IC50 = 13.74 μg/mL) assays, while its antimicrobial activity (15 μL) was determined via inhibition zone towards different microbial species (17.8–22.9 mm). On this basis, 0.1%, 0.2% and 0.3% v/v of EO solutions were used to immerse fresh sea bass samples at ~0 °C to form IG layers. The resulting samples were stored at −1 ± 0.2 °C for 25 days and analyzed by a series of freshness assays. Results showed that the treatment was effective in keeping the storage freshness of fish samples by retarding the spoilage of preserved fish samples in electric, chemical, microbial, textural and sensory properties. It can indicate that this SS-IG approach will have promising applications in aquaculture industry.

Available literature indicates that fish are able to recognize familiar conspecifics and that familiarity may offer important benefits (e.g. more stable social environment, improved foraging behavior, growth, survival). In the practice of intensive rearing of European seabass Dicentrarchus labrax mixing of familiar and unfamiliar conspecifics is very common following grading and fish with no previous contact with each other are forced to coexist. The aim of the present study was to investigate whether living with familiar or unfamiliar conspecifics is advantageous for European seabass. To mimic a grading procedure, two size classes were tested (small: 70.2 g and large fish: 96.2 g). Seventy two fish from mixed groups with prior nine-months familiarity were distributed, in groups of six, in twelve tanks to form familiar groups of small (FS) and large (FL) fish (fish selected from the same tank), and unfamiliar groups of small (US) and large (UL) fish (fish selected from six different tanks). All fish were individually marked and individual food consumption was used to rank individuals in the feeding hierarchy. Each treatment was triplicated and the experiment lasted for 75 days. Familiarity had no effect on fish growth performance. In all treatments a feeding hierarchy was established; fish of the highest feeding ranks had the higher mass and specific growth rate, consumed the majority of food offered with little daily variation and made more efforts to catch their food. This hierarchy was weaker in US compared to FS fish (lower correlation coefficients). Correlation coefficients between mean share of meal and coefficient of daily food consumption variation, which have been used as indicators of the strength of the social hierarchy, indicate US groups as the ones with the milder social environment. Familiarity effects on large fish social environment were minor The results of the present study suggest that, within the range of body mass examined, the mixing of unfamiliar conspecifics after performing a grading procedure is not indicated to be neither beneficial nor detrimental for European seabass productive traits. Moreover, milder social conditions seem to be established, at least in the smaller size class, which is of importance form the fish welfare point of view.

One of the goals of the aquaculture industry is to understand and control growth associated traits through selective breeding. In the present study the molecular basis of growth heterogeneity in the European sea bass (Dicentrarchus labrax) was addressed. To establish growth heterogeneity in a group of hatchery bred sea bass individuals were tagged and their specific growth rates (SGR) determined at monthly intervals. Gene expression in the brain, liver and white muscle from fish with the most divergent sustained SGR (6 individuals of the first and last quartile) was assessed using SuperSAGE (Serial Analysis Gene Expression) combined with next generation SOLiD4 sequencing. A total of approx. 11 million edited tags (26 bp), on average 2 million tags per SAGE library, that represented 47.071 unique transcripts were identified. Comparison of transcripts in fish with high and low SGR yielded 344, 698 and 601 differently expressed tags (0.01% false discovery rate and 4-fold change) in brain, liver and muscle, respectively. The tags were mapped onto the sea bass genome and approximately one third of the tags could be assigned to annotated genes. Pathway enrichment analysis revealed in liver, muscle and brain intricate gene expression changes in endocrine regulatory pathways involved in growth, metabolic and the stress axis, underlying divergent SGR in sea bass. Funding by the European Commission of the European Union through the Network of Excellence Marine Genomics Europe (contract GOCE-CT-2004-505403) and by the Portuguese Foundation for Science and Technology (FCT) info:eu-repo/semantics/publishedVersion

Financial support was given by FEDER through the Operational Program for Competitiveness Factors and COMPETE, through FCT and the Portuguese Foundation for Science and Technology under project PTDC/AGR/ALI/122119/2010, and projects ReNATURE - Valorization of the Natural Endogenous Resources of the Centro Region (Centro 2020, Centro-01-0145-FEDER-000007) and SmarBioR - Smart Valorization of Endogenous Marine Biological Resources Under a Changing Climate (Centro 2020, Centro-01-0145-FEDER-000018), cofunded by Centro 2020 Program, Portugal 2020, European Union, through the European Regional Development Fund. Authors also acknowledge FCT for the grant attributed to Sara Leston (grant SFRH/ BPD/91828/2012) and to João Rosa (grant SFRH/BD/102008/2014). The funding source did not interfere with the study design, or in the collection, analysis or interpretation of the data. It also had no involvement in the writing of the report and in the decision to submit the present manuscript for publication. Concerns about antibiotic use led to stricter legislations and overall better practices in aquaculture production. However, depletion time periods in tissues vary greatly with different antimicrobials, fish species, or experimental setup. In the present work, five drugs (sulfadiazine (SDZ), trimethoprim (TRI), flumequine (FLU), oxolinic acid (OXO), and oxytetracycline (OTC)) were incorporated into medicated feed, and their retention in European seabass muscle tissues assessed. Juveniles were placed in 300 L tanks at 18 °C and were manually fed with medicated feeds for a 7 day period (two concentrations per antimicrobial, ranging from 6 to 220 mg kg−1 , which were based on previous studies on the occurrence of these antimicrobials). Residues were analyzed through a multi-class quantification method (UHPLC-MS/MS). Data on residues concentration through time followed a one-compartment model, with TRI concentrations above the established Maximum Residue Level (MRL) throughout the experiment. Similarly, OTC concentrations at the highest dose were also above 100 μg kg−1 up to 14 days after the medication period. Results obtained for TRI may indicate the presence of a dose dependency for this antimicrobial. FLU concentrations in muscle samples were the lowest through time (Cday7 of 279.70 and 386.63 μg kg−1 , for prophylactic and therapeutic treatments, respectively). Half-life values of 14.37, 10.87, 5.36, 7.20, and 27.22 h (prophylactic treatment), and 20.95, 8.41, 5.61, 11.22, and 17.99 h (therapeutic treatment), were determined for SDZ, TRI, FLU, OXO, and OTC, respectively. Withdrawal times of 0, 2, and 5 days were determined for FLU, OXO, and SDZ, but sampling times for OTC and TRI should be longer, since antimicrobial concentrations were above the MRL 14 days after the end of the feeding period with medicated feed. Therefore, special attention should be given since they are the most used antibiotics in aquaculture and European seabass plays a major part in human nutrition in the Mediterranean region. info:eu-repo/semantics/publishedVersion

This study aims to understand the interactive effects of high dietary vegetable oils (VO) and carbohydrate (CH) content in European seabass cellular, humoral, and molecular innate immune responses to an acute stress. For that purpose, European sea bass juveniles (74.0 ± 1.5 g) were fed four diets differing in lipid source (fish oil (FO) or a blend of vegetable oils (VO)) and carbohydrate content (0% (CH–) or 20% (CH+) gelatinized starch). Nine fish per dietary treatment were sampled after 73 days of feeding and used as control whereas the remaining fish were subjected to an acute stress (netting, 1 min air exposure, and transfer to smaller tanks). Those fish were then sampled after 1 h and considered the stressed group. In the present study, dietary VO incorporation affected fish humoral immune parameters with a decrease of haematocrit, plasma peroxidase activity, and head-kidney mc2r and gr1 mRNA expression levels. Regardless of dietary treatment, higher cortisol levels were accompanied by an increase of several haematological, cellular, and humoral parameters in response to an acute stress. Dietary VO incorporation led to lower neutrophil numbers, plasma antiproteases activity, and head-kidney cox2 expression level in stressed fish. Fish fed CH+ diets showed a reduction of head-kidney mc2r expression levels in response to stress, while plasma cortisol remained unchanged, plasma NO decreases and antiproteases activity increased. In fish fed the VO diets, CH+ led to a decrease of plasma bactericidal activity compared to that of group CH-, while the opposite pattern was observed for plasma peroxidase. In conclusion, dietary substitution of FO by VO in CH– diet negatively affected the immune response in both undisturbed and stressed fish, while the effect of dietary CH incorporation in VO diet was not clear.

A total 180 marine fish samples, 60 of each mullet (Mugil cephalus), seabream (Sparus aurata) and seabass (Dicentrarchus labrax),were randomly collected from different fish farms in Port-Said Governorate. Some of collected fishes displayed hemorrhages on the external body surface, base of fins and operculum (gill cover) with congested gills, pale liver and corneal opacity were noticed. Bacteriological examination of samples was collected from fish surface, liver, kidney, spleen, muscle and gills revealed that the highest level of the isolates was recorded in liver followed by kidney, spleen, muscle and gill. Biochemical identification results of the isolated Vibrio species were revealed that 38 samples (21.11%) from the total collected samples were positive for the prevalence of Vibrio species at a percentage of (28.33%), (18.33%) and (16.67%) for mullet, seabream and seabass respectively. Molecular identification of Vibrio species isolated from some marine fishes using 16S rRNA and toxR revealed that 32 strains of the isolated Vibrio were belong to V. parahaemolyticus with a prevalence of 15, 8 and 9 from mullet, seabream and seabass respectively. Meanwhile molecular characterization of the identified V. parahaemolyticus by using PCR showed that all 32 isolates were harbored recA gene and only 25 isolates were harbored tlh gene. The public health hazards of this microorganism, as well as improve quality status of marine farms fishes were discussed. Keywords: Vibrio parahaemolytius, virulence, mullet, seabream, seabass fish, PCR, Public health.

Nowadays, Edwardsiella is considered the most dangerous bacterial problem in cultured fish farms. In this study, 100 diseased Nile tilapia (Oreochromis niloticus) and 100 diseased sea bass (Dicentrarchus labrax) were collected randomly from kafer El-sheikh cultured fish farms and also from Damietta Government during the period from May 2016 till May 2017. All diseased fishes showed hemorrhages, all over the body surface accompanied by swelling of abdomen were observed clinically and post-mortem. Liver, kidney and spleen samples were subjected to bacteriological examinations, for isolation of E. tarda. The suspected isolates were characterized morphologically and biochemically including microbact 24. PCR technique was applied for detection of some virulence genes (etfA, etfD, gyerB genes) in E. tarda isolates. Total prevalence of well identified E. tarda isolates was 12% in Oreochromis niloticus while 7% in Dicentrarchus labrax. Most E. tarda isolates were sensitive to ciprofloxacin, streptomycin chloramphenicol and gentamycin, conversely, most of isolates were resistant to tetracyclin, nalidixic acid, ampicillin, and sulphamethoxazole. PCR results recorded that all recovered E. tarda isolates contain gyerB at 415bp and etfD at 445 bp, while not all E. tarda posses etfAat 415bp .

In the current study, we report the thermal tolerance, standard metabolic rate (SMR) and preferred temperature of juvenile European sea bass (Dicentrarchus labrax) (1.2 ± 0.4 g) acclimated at 15, 20, 25 and 30 °C for 30 days. Dynamic and static thermal tolerance zones of juvenile European sea bass are 861 °C2 and 613 °C2, respectively. The European sea bass is a fish species with low thermal resistance, with a resistance zone area of 162.5 °C2. The SMR of the fish species at the above acclimation temperatures are 184, 255, 382 and 459 mg O2 h−1 kg−1, respectively and are significantly different (P

The effects of water temperature (15, 20 and 25 °C) on the stress response of European sea bass, Dicentrarchus labrax, were studied. Blood and water samples were collected prior and at 0.5, 1, 2, 4 and 8 h post-stress for hormonal and biochemical analysis. Water temperature affected the resting concentrations of all stress indicators examined, as well as their response after stress, apart from lactate which response was unaffected by temperature. Cortisol showed the response with the highest outcome at 15 °C, and the fastest at 25 °C. Cortisol release rate in the water was also faster and of higher magnitude at higher temperatures. Glucose had both the fastest and higher in magnitude response at 25 °C, while lactate responded similarly in all temperatures tested. Finally, osmolality changed only at the highest temperature. These results suggest that temperature should be taken into consideration when evaluating the resting levels of stress indicators of European sea bass in laboratory, rearing and field conditions. Additionally, the present results show that temperature affects the stress response, suggesting that fish can differ in their susceptibility to stress depending on the acclimatization temperature. Moreover, it was shown that cortisol release rate in the water, a non-invasive stress indicator, can depict the effects of temperature on cortisol stress response.

Seawater chlorination is widely used for coastal, marine industries for the prevention of fouling. Using a choice chamber system, we investigated the influence of chlorinated seawater at typical concentrations occurring near chlorinated cooling water discharges, on the behaviour of juvenile seabass (Dicentrachus labrax). These studies showed that there was evidence of an effect of chlorination, with models predicting 22% fewer fish present in the chlorine dosed chamber compared to the undosed chamber in all control runs (mean number of fish in the dosed chamber in all control runs was 2.23 in comparison to 1.74 when chlorine was present). These data suggest that when food is available D. labrax will enter areas that are at mean chlorination levels of 0.04 mg l−1, which are typical close to the discharge of power station cooling water but are more likely to move away once the food supply is reduced.

Understanding how marine fish early-life history is affected in the long-term by environmental and oceanographic factors is fundamental given its importance to population dynamics and connectivity. This work aimed at determining the influence of these processes on the interannual variability in hatch day and early-life growth patterns of European seabass, over a seven-year period (2011-2017) in the Atlantic Iberian coast. To accomplish this, otolith microstructure analysis was used to determine seabass hatch day and to develop early-growth correlations. In most years, hatching occurred from February to April, with two exceptions: in 2012, hatching started in early-January, and in 2016 an exceptionally long hatching period was registered. Using generalized additive models (GAM), we observed that sea surface temperature (SST), the North Atlantic Oscillation index (NAOi) and Chlorophyll-a (Chla) were the main drivers behind the inter-annual variability in seabass hatch day. Analysis of correlations between growth increments allowed assessing important periods of seabass growth and how future growth is affected. Since seawater temperature is among the main drivers for seabass recruitment and growth, its life cycle may be hampered due to ocean warming and an increasingly unstable climate, with consequences for the natural marine stocks and their harvest. PTDC/MAREST/2098/2014; 9471-RIDTI; POCI01-0145-FEDER-016787; CENTRO-01-0145-FEDER-000007 CENTRO-01-0145-FEDER-000007 info:eu-repo/semantics/publishedVersion

The female sex steroid 17β-oestradiol (E2) is involved in the regulation of numerous physiological functions, including the immune system development and performance. The role of oestrogens during ontogenesis is, however, not well studied. In rodents and fish, thymus maturation appears to be oestrogen-dependent. Nevertheless, little is known about the function of oestrogen in immune system development. To further the understanding of the role of oestrogens in fish immune system ontogenesis, fingerlings of European sea bass (Dicentrarchus labrax) were exposed for 30 days to 20 ng E2·L−1, at two ages tightly related to thymic maturation, i.e., 60 or 90 days post hatch (dph). The expression of nuclear and membrane oestrogen receptors was measured in the thymus and spleen, and the expression of several T cell-related gene markers was studied in both immune organs, as well as in the liver. Waterborne E2-exposure at 20.2 ± 2.1 (S.E.) ng·L−1 was confirmed by radioimmunoassay, leading to significantly higher E2-contents in the liver of exposed fish. The majority of gene markers presented age-dependent dynamics in at least one of the organs, confirming thymus maturation, but also suggesting a critical ontogenetic window for the implementation of liver resident γδ and αβ T cells. The oestrogen receptors, however, remained unchanged over the age and treatment comparisons with the exception of esr2b, which was modulated by E2 in the younger cohort and increased its expression with age in the thymus of the older cohort, as did the membrane oestrogen receptor gpera. These results confirm that oestrogen-signalling is involved in thymus maturation in European sea bass, as it is in mammals. This suggests that esr2b and gpera play key roles during thymus ontogenesis, particularly during medulla maturation. In contrast, the spleen expressed low or non-detectable levels of oestrogen receptors. The E2-exposure decreased the expression of tcrγ in the liver in the cohort exposed from 93 to 122 dph, but not the expression of any other immune-related gene analysed. These results indicate that the proliferation/migration of these innate-like T cell populations is oestrogen-sensitive. In regard to the apparent prominent role of oestrogen-signalling in the late thymus maturation stage, the thymic differentiation of the corresponding subpopulations of T cells might be regulated by oestrogen. To the best of our knowledge, this is the first study investigating the dynamics of both nuclear and membrane oestrogen receptors in specific immune organs in a teleost fish at very early stages of immune system development as well as to examine thymic function in sea bass after an exposure to E2 during ontogenesis., This research was supported by ANR financed project ETaT (ANR-15-CE32-0014), by FCT (project UID/Multi/04326/2019, fellowship SFRH/BPD/84033/2012 and contract with the University of Algarve with reference DL57/2016/CP6321/CT0015 for P.I.S.P.) and by the EU H2020 Research and Innovation Programme AQUAEXCEL2020 (grant agreement 652831; TNA project AE050029) and ASSEMBLE PLUS (contract SR02022018976f).

The European sea bass (Dicentrarchus labrax) is a euryhaline marine teleost that can often be found in brackish and freshwater or even in hypersaline environments. Here, we exposed sea bass juveniles to sustained salinity challenges for 15 days, simulating one hypoosmotic (3‰), one isosmotic (12‰) and one hyperosmotic (50‰) environment, in addition to control (35‰). We analyzed parameters of skin mucus exudation and mucus biomarkers, as a minimally invasive tool, and plasma biomarkers. Additionally, Na+/K+-ATPase activity was measured, as well as the gill mucous cell distribution, type and shape. The volume of exuded mucus increased significantly under all the salinity challenges, increasing by 130% at 50‰ condition. Significantly greater amounts of soluble protein (3.9 ± 0.6 mg at 50‰ vs. 1.1 ± 0.2 mg at 35‰, p &lt, 0.05) and lactate (4.0 ± 1.0 µg at 50‰ vs. 1.2 ± 0.3 µg at 35‰, p &lt, 0.05) were released, with clear energy expenditure. Gill ATPase activity was significantly higher at the extreme salinities, and the gill mucous cell distribution was rearranged, with more acid and neutral mucin mucous cells at 50‰. Skin mucus osmolality suggested an osmoregulatory function as an ion-trap layer in hypoosmotic conditions, retaining osmosis-related ions. Overall, when sea bass cope with different salinities, the hyperosmotic condition (50‰) demanded more energy than the extreme hypoosmotic condition.

An effective replacement for fish meal (FM) and fish oil (FO) based on plant-based raw materials in the feed of marine fish species is necessary for the sustainability of the aquaculture sector. However, the use of plant-based raw materials to replace FM and FO has been associated with several negative health effects, some of which are related to oxidative stress processes that can induce functional and morphological alterations in mucosal tissues. This study aimed to evaluate the effects of dietary oligosaccharides of plant origin (5,000 ppm; galactomannan oligosaccharides, GMOS) and a phytogenic feed additive (200 ppm; garlic oil and labiatae plant extract mixture, PHYTO) on the oxidative stress status and mucosal health of the gills of juvenile European sea bass (Dicentrarchus labrax). The experimental diets, low FM and FO diets (10%FM/6%FO) were supplemented with GMOS from plant origin and PHYTO for 63 days. GMOS and PHYTO did not significantly affect feed utilization, fish growth, and survival. GMOS and PHYTO downregulated the expression of β-act, sod, gpx, cat, and gr in the gills of the fish compared with that in fish fed the control diet. The expression of hsp70 and ocln was upregulated and downregulated, respectively, in the GMOS group compared with that in the control group, whereas the expression of zo-1 was downregulated in the PHYTO group compared with that in the GMOS group. The morphological, histopathological, immunohistochemical, and biochemical parameters of the fish gills were mostly unaffected by GMOS and PHYTO. However, the PHYTO group had lower incidence of lamellar fusion than did the control group after 63 days. Although the tissular distribution of goblet cells was unaffected by GMOS and PHYTO, goblet cell size showed a decreasing trend (−11%) in the GMOS group. GMOS and PHYTO significantly reduced the concentration of PCNA+ in the epithelium of the gills. The above findings indicated that GMOS and PHYTO in low FM/FO-based diets protected the gill epithelia of D. labrax from oxidative stress by modulating the expression of oxidative enzyme-related genes and reducing the density of PCNA+ cells in the gills of the fish.

Sea bass is a fish widely produced, consumed and appreciated in Italy. Its intensive rearing system provides the consumption of valuable fish to a wider population. Thanks to the use of an appropriate feed, it is possible to obtain reared sea bass which are richer in total lipid with a majority presence of polyunsaturated fatty acids, such as n-3 and n-6 families. In this study, a total of 75 specimens of European sea bass coming from three different origins (two farmed and one wild) were considered, 25 fish from each origin. Biometry traits were valued as of the chemical and fatty acid composition of fillets. Biometric indices, chemical composition and fatty acid profile resulted significantly affected by the rearing system. Fishes from the Intensive rearing system (IRS) showed the highest value of relative profile and condition factor; higher content of lipid and total n-6 that influenced the n-3/n-6 ratio and the atherogenic indexes; values that make their meats very healthy and indicated for human consumption as the wild fishes.

A very sensitive, selective, rapid and easy gas-phase preconcentration based method is presented for the determination and speciation of inorganic selenium in chicken meat, poultry eggs, mullet fish (Mugil Cephalus) and sea bass fish (Dicentrarchus Labrax) samples. Gold-coated W-coil atom trap was used to increase the sensitivity of conventional HG-AAS. LOD and LOQ values were calculated to be 0.021 μg/L and 0.070 μg/L, respectively. RSD% was found as 3.24. The sensitivity was increased 20 times more with the method used in the current study than the HG-AAS method. The interference effects of other metals on Se signal were significantly reduced by trap. SEM and EDX images of both bare and gold coated W-coil atom trap were screened. In order to check the accuracy of the method, “DOLT-5: Dogfish Liver” standard reference material was used and there was a good agreement between certified and found values at the 95% confidence level.

Fish in coastal ecosystems can be exposed to acute variations in CO2that can approach 1 kPa CO2(10,000 μatm). Coping with this environmental challenge will depend on the ability to rapidly compensate the internal acid-base disturbance caused by sudden exposure to high environmental CO2(blood and tissue acidosis); however, studies about the speed of acid-base regulatory responses in marine fish are scarce. We observed that upon exposure to ~1 kPa CO2, European sea bass (Dicentrarchus labrax) completely regulate erythrocyte intracellular pH within ~40 minutes, thus restoring haemoglobin-O2affinity to pre-exposure levels. Moreover, blood pH returned to normal levels within ~2 hours, which is one of the fastest acid-base recoveries documented in any fish. This was achieved via a large upregulation of net acid excretion and accumulation of HCO3− in blood, which increased from ~4 to ~22 mM. While the abundance and intracellular localisation of gill Na+/K+-ATPase (NKA) and Na+/H+exchanger 3 (NHE3) remained unchanged, the apical surface area of acid-excreting gill ionocytes doubled. This constitutes a novel mechanism for rapidly increasing acid excretion during sudden blood acidosis. Rapid acid-base regulation was completely prevented when the same high CO2exposure occurred in seawater with experimentally reduced HCO3− and pH, likely because reduced environmental pH inhibited gill H+excretion via NHE3. The rapid and robust acid-base regulatory responses identified will enable European sea bass to maintain physiological performance during large and sudden CO2fluctuations that naturally occur in coastal environments.Summary statementEuropean sea bass exposed to 1 kPa (10,000 μatm) CO2regulate blood and red cell pH within 2 hours and 40 minutes, respectively, protecting O2transport capacity, via enhanced gill acid excretion.

This experimental study determined internal distributions of an array of radio-elements (54Mn, 60Co, 65Zn, 134Cs, 241Am, 109Cd, 110mAg, 75Se and 51Cr) accumulated from seawater by three chondrichthyan fish species (Scyliorhinus canicula (dogfish), Raja undulata (undulate ray) and Torpedo marmorata (spotted torpedo)) and three teleost species (Scophthalmus maximus (turbot), Sparus aurata (seabream) and Dicentrarchus labrax (seabass)). The study tested the hypothesis that the chondrichthyan (cartilaginous) fish taxon and teleost (bony) fish taxon have different patterns of bioaccumulation of these radio-elements in six body components (head, digestive tract, liver, kidneys, skin and muscle), consistent with their long period of evolutionary divergence. Comparisons of body component CFs between the two taxa for each radio-element and the full array of radio-elements showed highly significant differences (p ≤ 0.001) between cartilaginous and bony fishes in each body component, confirming the existence of a strong and pervasive phylogenetic signal; however, the subset of radio-elements most determinant of these differences were unique for each body component. Partitioning between the three individual bony species and the three individual cartilaginous species also occurred repeatedly among their body components, particularly for bony fishes. Distributions of these radio-elements among body components were typically highly heterogeneous for both fish taxa.

Dicentrarchus punctatus (Bloch, 1792) Dicentrarchus punctatus: Ben-Tuvia, 1953a; Ben-Tuvia, 1971a; Ben-Tuvia, 1971b (Syst.); Paperna, 1972 (Parasit.); Darom & Tsurnamal, 1992 (Heb.); Golani, 1996; Golani, 1997 (Heb.); Ethad, 2004 (Heb.); Golani, 2005; Edelist et al., 2011a (Fish.). CALANTHIIDAE, Published as part of Golani, Daniel, 2021, An updated Checklist of the Mediterranean fishes of Israel, with illustrations of recently recorded species and delineation of Lessepsian migrants, pp. 1-108 in Zootaxa 4956 (1) on page 39, DOI: 10.11646/zootaxa.4956.1.1, http://zenodo.org/record/4691195, {"references":["Ben-Tuvia, A. (1953 a) Mediterranean fishes of Israel. Bulletin of the Sea Fisheries Research Station, Haifa, 8, 1 - 40.","Ben-Tuvia, A. (1971 a) Revised list of the Mediterranean fishes of Israel. Israel Journal of Zoology, 20, 1 - 39.","Ben-Tuvia, A. (1971 b) On the occurrence of the Mediterranean serranid fish Dicentrarchus punctatus (Bloch) in the Gulf of Suez. Copeia, 1971, 741 - 743. https: // doi. org / 10.2307 / 1442650","Paperna, I. (1972) Parasitological implications of fish migration through interoceanic canals. 17 e Congress of Internatioal Zoology, Monte Carlo, 5 + iv pp. [mimeo]","Darom, D. & Tsurnamal, M. (1992) Handbook of the Seashores of Israel. Keter Publishing House, Ltd., Jerusalem, 271 pp. [in Hebrew]","Golani, D. (1997) Handbook of the Fishes of Israel. Keter Publishing House Ltd. Jrusalem. 269 pp. [in Hebrew].","Ethad, D. (2004) Fishes caught in the Electric Company's Haifa power station's filtering systems in relation to environmental conditions and in comparison to fish assemblages from ancient coastal sites. M. Sc. Thesis. University of Haifa, 98 + 4 pp. [in Hebrew with English abstract]","Edelist, D., Sonin, O., Golani, D., Rilov, G. & Spanier, E. (2011 a) Spatiotemporal patterns of catch and discards of the Israeli Mediterranean trawl fishery in the early 1990 s: ecological and conservation perspectives. Scientia Marina, 75 (4), 641 - 652. https: // doi. org / 10.3989 / scimar. 2011.75 n 4641"]}

The European sea bass (Dicentrarchus labrax) exhibits female-biased sexual size dimorphism (SSD) early in development. New tagging techniques provide the opportunity to monitor individual sex-related growth during the post-larval and juvenile stages. We produced an experimental population through artificial fertilization and followed a rearing-temperature protocol (~16°C from hatching to 112 days post-hatching, dph; ~20°C from 117 to 358 dph) targeting a roughly balanced sex ratio. The fish were tagged with microchips between 61 and 96 dph in five tagging trials of 50 fish each; individual standard length (SL) was recorded through repeated biometric measurements performed between 83 to 110 dph via image analyses. Body weight (BW) was modelled using the traits measured on the digital pictures (i.e. area, perimeter and volume). At 117 dph, the fish were tagged with microtags and regularly measured for SL and BW until 335 dph. The experiment ended at 358 dph with the sexing of the fish. The sex-ratio at the end of the experiment was significantly in favor of the females (65.6% vs. 34.4%). The females were significantly longer and heavier than the males from 103 dph (~30 mm SL, ~0.44 g BW) to 165 dph, but the modeling of the growth curves suggests that differences in size already existed at 83 dph. A significant difference in the daily growth coefficient (DGC) was observed only between 96 and 103 dph, suggesting a physiological or biological change occurring during this period. The female-biased SSD pattern in European sea bass is thus strongly influenced by very early growth differences between sexes, as already shown in previous studies, and in any case long before gonadal sex differentiation has been started, and thus probably before sex has been determined. This leads to the hypothesis that early growth might be a cause rather than a consequence of sex differentiation in sea bass.

The pressurized liquid extraction (PLE) technique was used, for the first time, to obtain protein extracts with antioxidant activity from side streams (muscle, heads, viscera, skin, and tailfins) of gilthead sea bream (Sparus aurata) in order to give added value to these underutilized matrices. Extraction conditions previously optimized for sea bass (Dicentrarchus labrax) side streams were applied. Protein recovery percentages were 22% (muscle), 33% (heads), 78% (viscera), 24% (skin), and 26% (tailfins), which represented an increase of 1.2–4.5-fold compared to control samples (extraction by stirring). The SDS-PAGE profiles revealed that PLE-assisted extraction influenced protein molecular weight distribution of the obtained extracts. PLE conditions also allowed increasing the antioxidant capacity measured by both Trolox equivalent antioxidant capacity (TEAC, 1.3–2.4 fold) and oxygen radical absorbance capacity (ORAC, 1.9–6.4) assays for all fish extracts. Inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (LC-ESI-qTOF-MS) were used to investigate the presence of toxic metals and mycotoxins in sea bream side streams. The levels of As, Hg, Cd, and Pb were below those established by authorities for fish muscle for human consumption (except for Cd in viscera samples). Through a nontargeted screening approach, no mycotoxins or related metabolites were detected for all sea bream side streams. This study contributes to the research on the valorization of fish processing side streams using environmentally friendly technology.

© 2021 Basto, Calduch-Giner, Oliveira, Petit, Sá, Maia, Fonseca, Matos, Pérez-Sánchez and Valente., [Objective]: This study aims to determine the maximal inclusion level of defatted (d-) Tenebrio molitor larvae meal (TM) able to replace dietary fishmeal (FM) without compromising growth performance, general metabolism, and flesh quality traits in European sea bass, and to evaluate the major underlying physiological mechanisms. [Materials and Methods]: Fish (55 ± 2 g) were fed with diets containing increasing levels of dTM: 0, 40, 80 and 100% (CTRL, TM40, TM80, and TM100, respectively) to replace FM. After 10 weeks of feeding, the growth performance, nutrient and energy balance, intestinal integrity, plasma metabolites and the expression of genes related to growth and nutrient metabolism, in liver and muscle were determined. The fatty acids (FA) profile, textural properties and color were also evaluated in muscle. [Results]: Protein and lipids digestibility remained unaltered up to 80% dTM inclusion. Growth performance parameters were similar among dietary treatments. The dTM inclusion increased the hepatosomatic index in fish fed TM100. Muscle eicosapentaenoic acid, docosahexaenoic acid and n-3 long-chain polyunsaturated FA levels were maintained up to 80% dTM inclusion, but total cholesterol and non-esterified FA increased with dietary dTM inclusion. In liver, the expression of elongation of very long-chain FA protein 6 (elovl6) and FA desaturase 2 (fads2) did not change in fish fed TM40 and TM80, but elovl6 decreased whilst fads2 increased in fish fed TM100 when compared to those fed CTRL. The expression of cholesterol 7 alpha-monooxygenase (cyp7a1) decreased with dietary dTM inclusion. In muscle, the expression of myoblast determination protein-2 (myod2) decreased in fish fed TM80 and TM100. [Conclusion]: It is feasible to substitute dietary FM by dTM up to 80% in European sea bass without detrimental effects on nutrient digestibility, growth performance and associated genetic pathways, whilst assuring fillet nutritional value for human consumption., This work was funded by the EU H2020 Research Innovation Program under the TNA Program (project AE090027) at IATS-CSIC Research Infrastructure within AQUAEXCEL2020 Project (652831). Additional financial support was received by the structured program of R&D&I ATLANTIDA - Platform for the monitoring of the North Atlantic Ocean and tools for the sustainable exploitation of the marine resources (reference NORTE-01-0145-FEDER-000040), supported by the North Portugal Regional Operational Programme (NORTE2020), through the European Regional Development Fund (ERDF) and by ANIMAL4AQUA Project, funded by Portugal 2020, financed by ERFD through COMPETE – POCI-01-0247-FEDER – 017610. This output reflects only the author’s view and the European Union cannot be held responsible for any use that may be made of the information contained herein. AB and MM were financially supported by FCT, Portugal (SFRH/BD/138593/2018 and DL57 – Norma transitória, respectively). Financial support from FCT – Foundation for Science and Technology within the scope of UIDB/04423/2020 and UIDP/04423/2020 is also acknowledged.

Disease outbreaks continue to represent one of the main bottlenecks for the sustainable development of the aquaculture industry. In marine aquaculture, many species from the Vibrio genus are serious opportunistic pathogens responsible for significant losses to producers. In this study, the effects on the immune response and the skin microbiota of European sea bass (Dicentrarchus labrax) were studied after a natural disease outbreak caused by V. harveyi. Data obtained from infected and non-infected fish were studied and compared. Regarding the local immune response (skin mucus) a decrease in the protease activity was observed in infected fish. Meanwhile, at a systemic level, a decrease in protease and lysozyme activity was reported while peroxidase activity showed a significant increase in serum from infected fish. A clear dysbiosis was observed in the skin mucus microbiota of infected fish in comparison with non-infected fish. Moreover, V. harveyi, was identified as a biomarker for the infected group and Rubritalea for healthy fish. This study highlights the importance of characterizing the mucosal surfaces and microbial composition of the skin mucus (as a non-invasive technique) to detect potential disease outbreaks in fish farms.

Climate change causes warming, decreased O2, and increased CO2 in marine systems and responses of organisms will depend on interactive effects between these factors. We provide the first experimental assessment of the interactive effects of warming (14 to 22°C), reduced O2 (∼3 – 21 kPa O2), and increased CO2 (∼400 or ∼1000 µatm ambient CO2) on four indicators of aerobic performance (standard metabolic rate, SMR, maximum metabolic rate, MMR, aerobic scope, and hypoxia tolerance, O2crit), blood chemistry, and O2 transport (P50) of a marine fish, the European sea bass (Dicentrarchus labrax). Warming increased SMR and O2crit (i.e. reduced hypoxia tolerance) as well as MMR in normoxia but there was an interactive effect with O2 so that hypoxia caused larger reductions in MMR and aerobic scope at higher temperatures. Increasing CO2 had minimal effects on SMR, MMR and O2crit and did not show interactive effects with temperature or O2 for any measured variables. Aerobic performance was not linked to changes in blood chemistry or P50. Despite lack of effects of CO2 on aerobic performance, increased CO2 induced 30% mortality of fish exercised in low O2 at 22°C indicating important threshold effects independent of aerobic performance. Overall, our results show temperature and O2, but not CO2, interact to affect aerobic performance of sea bass, disagreeing with predictions of the oxygen- and capacity-limited thermal tolerance hypothesis.

© 2021 Piazzon, Mladineo, Dirks, Santidrián Yebra-Pimentel, Hrabar and Sitjà-Bobadilla., Ceratothoa oestroides (Cymothoidea, Isopoda) is a generalist crustacean parasite that negatively affects the economic sustainability of European sea bass (Dicentrarchus labrax) aquaculture in the North-East Mediterranean. While mortalities are observed in fry and fingerlings, infection in juvenile and adult fish result in approximately 20% growth delay. A transcriptomic analysis (PCR array, RNA-Seq) was performed on organs (tongue, spleen, head kidney, and liver) from infected vs. Ceratothoa-free sea bass fingerlings. Activation of local and systemic immune responses was detected, particularly in the spleen, characterized by the upregulation of cytokines (also in the tongue), a general reshaping of the immunoglobulin (Ig) response and suppression of T-cell mediated responses. Interestingly, starvation and iron transport and metabolism genes were strongly downregulated, suggesting that the parasite feeding strategy is not likely hematophagous. The regulation of genes related to growth impairment and starvation supported the growth delay observed in infected animals. Most differentially expressed (DE) transcripts were exclusive of a specific organ; however, only in the tongue, the difference between infected and uninfected fish was significant. At the attachment/feeding site, the pathways involved in muscle contraction and intercellular junction were the most upregulated, whereas the pathways involved in fibrosis (extracellular matrix organization, collagen formation, and biosynthesis) were downregulated. These results suggest that parasite-inflicted damage is successfully mitigated by the host and characterized by regenerative processes that prevail over the reparative ones., This work was funded by the EU H2020 program through the ParaFishControl Project (634429). This publication reflects only the authors' views and the European Union cannot be held responsible for any use that may be made of the information contained herein. MCP was funded by a Ramón y Cajal Postdoctoral Research Fellowship (RYC2018-024049-I/AEI/10.13039/501100011033 co-funded by the European Social Fund (ESF) & ACOND/2020 Generalitat Valenciana). We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)