Bass Dicentrarchus Labrax Research Articles

Using Telemetry Sensors Mapping the Energetic Costs in European Sea Bass (Dicentrarchus labrax), as a Tool for Welfare Remote Monitoring in Aquaculture

Physiological real-time monitoring could help to prevent health and welfare issues in farmed fishes. Among physiological features that can be of interest for such purposes, there is the metabolic rate. Its measurement remains, however, difficult to be implemented in the field. Thus, mapping the fish acceleration recorded by tag with the oxygen consumption rate (MO2) could be promising to counter those limitations and to be used as a proxy for energy expenditure in the aquaculture environments. In this study, we investigated the swimming performance (Ucrit) and the swimming efficiency (Uopt, COTmin), and we estimated the metabolic traits (standard and maximum metabolic rates, SMR and MMR, as well the absolute aerobic scope, AS) of European sea bass (Dicentrarchus labrax; n = 90) in swimming tunnel. Among all tested fish, 40 fishes were implanted with an acoustic transmitter to correlate the acceleration recorded by the sensor with the MO2. In this study, the mean SMR, MMR, and AS values displayed by sea bass were 89.8, 579.2, and 489.4 mgO2 kg−1 h−1, respectively. The Uopt and COTmin estimated for sea bass were on average 1.94 km h−1 and 113.91 mgO2 kg−1 h−1, respectively. Overall, implantation of the sensor did not alter fish swimming performance or induced particular stress, able to increase MO2 or decrease swimming efficiency in tagged fish. Finally, acceleration recorded by tag has been successfully correlated with MO2 and fish mass using a sigmoid function (R2 = 0.88). Overall, such results would help for real-time monitoring of European sea bass health or welfare in the aquaculture environment in a framework of precision livestock farming.

Characterization of Erythroferrone in a Teleost Fish (Dicentrarchus labrax) With Two Functional Hepcidin Types: More Than an Erythroid Regulator.

Erythroferrone is a recently identified erythroid regulator produced by erythroblasts in the mammalian bone marrow and extramedullary sites, known to be induced in conditions of anemia or blood loss. Iron metabolism is affected by erythroferrone through its capacity to inhibit hepcidin production, leading to the increase of iron availability required for erythropoiesis. However, little is known about erythroferrone function in other vertebrates, in particular teleost fish, that unlike mammals, present two different functional types of hepcidin, one type mostly involved in iron metabolism and the other in antimicrobial response. The study of erythroferrone evolution and its biological role in teleost fish can give us valuably new insights into its function. To address these questions, we characterized erythroferrone in the European sea bass (Dicentrarchus labrax), a species presenting two hepcidin types, and evaluated variations in its expression levels in response to different experimental conditions. During experimental anemia, erythroferrone responds by increasing its expression and suppressing hepcidin production, following the pattern observed in mammals, but it is not influenced by iron overload. However, during bacterial infection, erythroferrone is downregulated and hepcidin levels increase. Furthermore, administration of Hamp1 but not of Hamp2 peptides suppresses erythroferrone expression. In conclusion, in dual hepcidin teleost fish erythroferrone seems to only interact with type 1 hepcidin, known to be involved in iron homeostasis, but not with type 2, which has an almost exclusive antimicrobial role.

Growth performance parameters of European Sea bass (Dicentrarchus Labrax) cultured in marine water farm and fed commercial diets of different protein levels

Growth performance parameters of European Sea bass (Dicentrarchus Labrax) cultured in marine water farm and fed commercial diets of different protein levels

Antioxidant Activities and Selenogene Transcription in the European Sea Bass (Dicentrarchus labrax) Liver Depend, in a Non-linear Manner, on the Se/Hg Molar Ratio of the Feeds

Feeding 3.9 and 6.7 mg Hg/kg (Se/Hg molar ratios of 0.8 and 0.4, respectively) for 14 days negatively affected Dicentrarchus labrax growth and total DNTB- and thioredoxin-reductase (TrxR) activities and the transcription of four redox genes (txn1, gpx1, txnrd3, and txnrd2) in the liver, but a diet with 0.5 mg Hg/kg (Se/Hg molar ratio 6.6) slightly increased both reductase activities and the transcription of txn1, gpx1, and txnrd2. Feeding 6.7 mg Hg/kg for 53 days downregulated the genes of the thioredoxin system (txn1, txnrd3, and txnrd2) but upregulated gpx1, confirming the previously proposed complementarity among the antioxidant systems. Substitution of 20% of the feed by thawed white fish (hake) slightly counteracted the negative effects of Hg. The effects were not statistically significant and were dependent, in a non-linear manner, on the Se/Hg molar ratio of the feed but not on its Hg concentration. These results stress the need to consider the Se/Hg molar ratio of the feed/food when evaluating the toxicity of Hg.

Phenotypic Convergence in Sea Bass (Dicentrarchus labrax) Escaping From Fish Farms: The Onset of Feralization?

The impact of fish escaping from fish farms may depend on the extent to which escapees adapt to the natural environment, resemble wild conspecifics, and become feral. Yet, little is known about the process of feralization in marine fish. We examined phenotypic changes in body shape, body condition, and scale growth profiles of sea bass escaping from fish farms in the Canary Islands and quantified the extent to which escapees had diverged from farmed conspecifics. Most feral sea bass had sizes that overlapped with those of farmed fish, indicating that they had escaped throughout the production cycle. However, 29% of escapees were larger than the maximum size at harvesting, indicating growth in the wild. Analysis of scale growth profiles showed that some escapees had grown in the wild as fast as cultured fish, albeit at more variable growth rates. Feral sea bass tended to converge towards a similar body shape, having more streamlined bodies, lower body condition, and lower hepatosomatic indices (HSI) than fish in cages. Although our study cannot discriminate between phenotypic plasticity and differential mortality of escapees, we interpret phenotypic convergence as the likely result of a period of initial starvation, phenotypic plasticity, and selection against maladapted phenotypes. Our results warn against the risks of rearing sea bass in open-net cages and suggest that sea bass escapees could pose a threat to shallow coastal assemblages, particularly in areas where the species is not naturally found.

Family-effects in the epigenomic response of red blood cells to a challenge test in the European sea bass (Dicentrarchus labrax, L.)

BackgroundIn fish, minimally invasive blood sampling is widely used to monitor physiological stress with blood plasma biomarkers. As fish blood cells are nucleated, they might be a source a potential new markers derived from ‘omics technologies. We modified the epiGBS (epiGenotyping By Sequencing) technique to explore changes in genome-wide cytosine methylation in the red blood cells (RBCs) of challenged European sea bass (Dicentrarchus labrax), a species widely studied in both natural and farmed environments.ResultsWe retrieved 501,108,033 sequencing reads after trimming, with a mean mapping efficiency of 73.0% (unique best hits). Minor changes in RBC methylome appeared to manifest after the challenge test and a family-effect was detected. Only fifty-seven differentially methylated cytosines (DMCs) close to 51 distinct genes distributed on 17 of 24 linkage groups (LGs) were detected between RBCs of pre- and post-challenge individuals. Thirty-seven of these genes were previously reported as differentially expressed in the brain of zebrafish, most of them involved in stress coping differences. While further investigation remains necessary, few DMC-related genes associated to the Brain Derived Neurotrophic Factor, a protein that favors stress adaptation and fear memory, appear relevant to integrate a centrally produced stress response in RBCs.ConclusionOur modified epiGBS protocol was powerful to analyze patterns of cytosine methylation in RBCs of D. labrax and to evaluate the impact of a challenge using minimally invasive blood samples. This study is the first approximation to identify epigenetic biomarkers of exposure to stress in fish.

Temporal and spatial variation in adult and juvenile mobile fauna associated with natural and artificial coastal habitats

Coastal habitats are important for commercially exploited and protected species of fish and larger mobile invertebrates. The addition of artificial structures within the marine environment has the potential to alter the connectivity between habitats and to affect metapopulations of a region. Baited remote underwater videos (BRUV) were used to investigate the spatial and seasonal variation in abundance of adult and juvenile mobile species associated with subtidal natural and artificial habitats within Poole Bay on the south coast of England in 2019. Metrics included the relative maximum abundance (MaxN), number of species seen (S), assemblage structure and size range of fish. Higher values of MaxN and S were recorded on artificial structures in the spring and early summer; however, this pattern was reversed by mid-summer and early autumn when more fish were recorded on the natural reefs. Yet overall differences in MaxN and S between habitats were not significant. Differences in assemblage composition between habitats varied monthly, but this was mostly driven by particular sites. Although most fish observed were juveniles, there were some seasonal differences in the size of fish using natural and artificial sites, especially bib (Trisopterus luscus), black bream (Spondyliosoma cantharus), bass (Dicentrarchus labrax) and pollack (Pollachius pollachius). The artificial habitats in this region appeared to be important in certain months, so temporal studies of this type need to be incorporated within surveys, particularly those in proximity to protected areas.

Trophic structure and resource utilization of the coastal fish community in the western Wadden Sea: evidence from stable isotope data analysis

We studied the trophic structure of the western Wadden Sea fish community through stable isotope analysis (δ13C and δ15N) of 1658 samples from 57 fish species collected between 2012 and 2016. Stable isotope values differed between species but did not vary between years or seasons, and only for some species with fish size. Stable isotope values were not different between immigrating (spring) and emigrating (autumn) fish, suggesting a similar trophic niche of the various fish species in the coastal zone and inside the Wadden Sea. For the majority of species, average δ13C values were within the range of -12 to -20.5‰, showing that both (marine) pelagic and benthic primary producers were at the base of the food web. Average δ15N values varied among species from 13-18‰, resulting in estimated trophic positions (TPs) of 2.1-5.5 with the majority between 2.2 and 3.5. Thick-lipped grey mullet Chelon labrosus, golden grey mullet C. aurata, greater pipefish Syngnathus acus and pilchard Sardina pilchardus had the lowest TP (2.2-2.4). Among the common species (>10 observations), the highest TP values (3.4-3.5) were found for twaite shad Alosa fallax, smelt Osmerus eperlanus, bull-rout Myoxocephalus scorpius, bass Dicentrarchus labrax and cod Gadus morhua. For all species, estimated TPs based on isotope values were lower than those based on stomach content composition (2.0-4.7), which could be explained by species-specific differences in trophic fractionation or by underestimation of the contribution of smaller prey species in the stomach content analysis. The trophic niche space of benthopelagic species was the smallest and overlapped with that of the pelagic and benthic species. In terms of area use, trophic niche space was smaller for juvenile marine migrant species (nursery-type species) and overlapped with that of the (near-)resident species and marine seasonal visitors. Potentially, trophic competition is highest for the functional group of benthopelagic species and the guild of juvenile marine migrant species (nursery-type species).

Draft Genome Sequence of Mycobacterium hippocampi DL, Isolated from European Sea Bass (Dicentrarchus labrax).

Mycobacterium hippocampi is an acid-fast opportunistic pathogen associated with infections in aquatic animals. Here, we report the draft genome sequence of M. hippocampi strain DL, an isolate from cultured European sea bass (Dicentrarchus labrax) associated with systemic symptomatology.

Dietary Supplementation of Enzymes for Promoting the Growth Performance and Health Of European Sea Bass (Dicentrarchus labrax)

This study was aimed to investigate the effects of dietary supplementation with exogenous enzymes such as phytase and protease enzymes on the growth performance, haemato-immunological, antioxidative status, and intestinal histomorphometry of European seabass (Dicentrarchus labrax). One hundred and fifty Sea bass (Dicentrarchus labrax) fingerlings with an initial body weight of 20 ± 2 g were obtained from Borg Al-Arab, Mariout regain at Alexandria Governorate, Egypt. The fingerlings were stocked into 15 fiberglass tanks (each with 30 m3) at the same. Each tank was stocked with 10 fish. The two exogenous enzymes used for the trial were phytase and protease. Two of the formulated diets were supplemented with the exogenous (phytase and protease at two doses from both 1000 mg kg-1 and 2000 mg kg-1, respectively) and the basal diet served as control diet. Our results concluded that, enzymes play an important role in formulating eco-friendly aqua-feeds. The use of enzymes as a feed additive has rapidly expanded and significant use in aqua-feed. Although the economic and social benefits of enzymes have been well established, the future of feed enzymes is a bright one in the aquaculture industry. From the current study, it can be concluded that dietary supplementation with protease and phytase has the potential to improve the growth performance, haemato-immunological, and antioxidative parameters of cultured sea bass. Additionally, the best inclusion dose of protease and phytase enzymes is a 2000 mg/kg diet. Further quantitative studies are necessary to confirm how exogenous enzymes (especially protease and phytase) modulate intestinal microbiota.

In vitro study of the serum effect on the supplementation of sea bass (Dicentrarchus labrax) head-kidney macrophage culture medium: Effect on the immune response

In vitro study of the serum effect on the supplementation of sea bass (Dicentrarchus labrax) head-kidney macrophage culture medium: Effect on the immune response

Differential immune responses of European sea bass (Dicentrarchus labrax) upon nodavirus infection by bath or intramuscular injection

Differential immune responses of European sea bass (Dicentrarchus labrax) upon nodavirus infection by bath or intramuscular injection

Detection and quantification of 47 antibiotic residues in farmed European sea bass (Dicentrarchus labrax) using a multi-class and multi-residue UHPLC-MS/MS method

ABSTRACTIn 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−1.

Rapid Multiparameters Approach to Differentiate Fresh Skinless Sea Bass (Dicentrarchus labrax) Fillets from Frozen-Thawed Ones

ABSTRACTFood authenticity is one of the major issues in the mind of today’s consumers. The sale of frozen-thawed fish fillets under the “fresh fillet” label is considered as a commercial fraud. However, their close sensory properties complicate the differentiation. This study focused on analyzing the composition of exudate (pressured flesh juice) in order to rapidly differentiate between fresh and frozen-thawed skinless fillets of sea bass (Dicentrarchus labrax). Protein concentration, α-D-glucosidase specific activity, nucleotides and related compounds (NRCs) concentration, and free calcium concentration were measured in exudates corresponding to fresh or frozen-thawed sea bass fillets. Significant increases of these four parameters were observed in exudates from frozen-thawed fillets, especially with a twofold increase in NRCs and free calcium concentrations. These results suggest that NRCs and free calcium concentrations can be promising indicators to rapidly detect mislabeling of fresh fillets.

Anti-parasitic activity of garlic (Allium sativum) and onion (Allium cepa) juice against crustacean parasite, Lernantropus kroyeri, found on European sea bass (Dicentrarchus labrax)

The copepod parasite Lernantropus kroyeri impairs the productivity of European sea bass (Dicentrarchus labrax) culture by leading to a direct infection or as a vector for other disease agents. In current conditions, the parasitic infections in mariculture are usually treated with the chemicals, mainly with the pesticides. However, therapeutic chemical use has potential risks on the overall aquatic environment. Thus, the aquaculture sector needs to find alternative substances to the treatment or prophylaxis of the diseases instead of chemicals. In the present study, in vitro exposure tests were performed to elucidate the effects of garlic (Allium sativum) and onion (Allium cepa) on adult L. kroyeri. Female individuals of L. kroyeri were exposed to different concentrations of garlic or onion juice (20, 40, 60, 80 and 100% of the plant juice) for a specified time. Garlic juice exposure at a ratio of 100% resulted in instantaneous death of all individuals in five minutes. Although the killing time varied by the concentration, garlic juice killed the L. kroyeri females within 30 min even at the lowest concentration. Onion juice had lower killing effect at low concentrations, however, higher concentrations of onion juice killed the female parasites within 60 min. Results revealed that garlic and onion juices had killing effect on L. kroyeri females in a time and concentration-dependent manner. It can be concluded that against parasitic copepods alternative solutions can be developed in aquaculture, using these plant juices with emphasising necessity of further in vivo tolerance tests in fish.HighlightsGarlic and onion juices had anti-parasitic effect in vitro on the crustacean parasite, Lernantropus kroyeri found on the gills of European sea bass (Dicentrarchus labrax).After exposure of L. kroyeri to garlic and onion juices, the mortality was time and concentration-dependent.The killing activity of garlic juice for L. kroyeri was stronger than that of onion juice.

Persistent organic pollutants in farmed European sea bass (Dicentrarchus labrax, Linnaeus, 1758) from Sicily (Italy)

ABSTRACTFarmed European sea bass (Dicentrarchus labrax, Linnaeus, 1758) were collected during 2016 from one Sicilian fish farm that uses two different rearing systems – sea cage and concrete tank – for determination of polychlorinated biphenyls (PCB), organochlorine pesticides (OCP) and polycyclic aromatic hydrocarbons (PAH) residues by HRGC-MS/MS. Moreover, commercial feed was analysed. This study aimed to determine whether the different rearing systems affect the concentration of these compounds, and to assess the safety of cultured fish. PCBs represent the pollutants with the highest concentration; in particular, PCB138 and 153 have the highest concentration in almost all samples. Among OCPs, only 4,4′-DDE, 4,4′-DDD and 4,4′-DDT residues have been detected. Concerning PAHs, only fluorene and phenanthrene were detected, in both rearing systems. Although some residues of organic pollutants were found in the analysed samples, they were always below the MRLs, so the results suggest that farmed sea bass are safe for human consumption.

Amino Acid Requirements of Gilthead Bream (<i>Sparus aurata</i>) Juveniles

In one trial 120 gilthead bream fingerlings received tow different feed mixtures containing two different levels of protein (diet A.400 and B 360 gkg-1). The average initial live weight was about 2.2 ±0.1 g fish-1 in each replicate of all treatments. Twenty fish per aquarium were stocked randomly in 6 glass aquaria (120 l each). Fish were fed with experimental diets at rate 8 % of the body weight daily. The amino acids (AA) content was in the diets, whole fish and muscle at the end of the growth period (60 days). The results indicated that, at the end of experiment Sea bass fry had reached an average live weight 18.5 and 16.2 g fish-1 for fish fed diet A and B respectively. Also the increase of protein levels in the feed to 40% caused a significant decrease in the content of indispensable amino acid (IAA) and dispensable amino acid (as %v of whole fish and muscle of wet weight). Tow methods were subsequently used to estimate the quantitative IAA requirements of Sea bass fry based on the hypothesis that (a) the dietary requirement pattern of IAA reflects the tissue pattern and (b) the rate of daily deposition in the fish can be equated with the dietary requirement as percentage of 100 g-1 diet. The quantitative IAA requirement (%) of Sea bass (Dicentrarchus labrax) diets as follow: Lysine 2.27, Methionine 1.09, Therionine 0.61, Leucine 2.4, Isoleucine 0.47, Histidine1.6, Arginine 1.39, Phenylalanine 1.43, Valine 1.22 and Tryptophane 0.42.

Nutritional quality of different fish species farmed in the Adriatic Sea

The nutritional quality of commercially important farmed fish species, i.e. sea bream (Sparus aurata), sea bass (Dicentrarchus labrax), dentex (Dentex dentex) and turbot (Scophthalmus maximus) was investigated. Dentex was shown to have twice as high omega-3 fatty acid content and two to four times higher eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid content as compared to other fish species. The recommended n-6/n-3 ratio was determined in all fish species, whereas the recommended PUFA/SFA ratio was not seen in turbot. Except of turbot, all other fish species matched the recommended atherogenic index (AI), the thrombogenic index (TI) and the ratio of hypocholesterolemic over hypercholesterolemic fatty acids (HH), while the highest the flesh lipid quality (FLQ) value was determined in dentex.

Nondestructive Semistatic Testing Methodology for Assessing Fish Textural Characteristics via Closed-Form Mathematical Expressions

This paper presents a novel methodology based on semistatic nondestructive testing of fish for the analytical computation of its textural characteristics via closed-form mathematical expressions. The novelty is that, unlike alternatives, explicit values for both stiffness and viscoelastic textural attributes may be computed, even if fish of different size/weight are tested. Furthermore, the testing procedure may be adapted to the specifications (sampling rate and accuracy) of the available equipment. The experimental testing involves a fish placed on the pan of a digital weigh scale, which is subsequently tested with a ramp-like load profile in a custom-made installation. The ramp slope is (to some extent) adjustable according to the specification (sampling rate and accuracy) of the equipment. The scale’s reaction to fish loading, namely, the reactive force, is collected throughout time and is shown to depend on the fish textural attributes according to a closed-form mathematical formula. The latter is subsequently used along with collected data in order to compute these attributes rapidly and effectively. Four whole raw sea bass (Dicentrarchus labrax) of various sizes and textures were tested. Changes in texture, related to different viscoelastic characteristics among the four fish, were correctly detected and quantified using the proposed methodology.

Gonadal sexual differentiation of European sea bass (Dicentrarchus labrax, L. 1758) of fingerlings in different size classes

This report describes a study of the gonad differentiation in fingerlings of European sea bass (Dicentrarchus labrax) belonging to different size groups. Fishes were divided into four groups according to their weight: Group 1 (4.5 ± 0.7 g), Group 2 (9.2 ± 0.8 g), Group 3 (14.8 ± 1.8 g), and Group 4 (21.8 ± 2.3 g). In all groups, low percentages of undifferentiated or early sexually differentiated fish were found. Higher percentages of fully differentiated ovaries were found in Groups 1 and 3. Fully differentiated testes occurred in 90% of Group 4. Ninety percent of fish in Group 2 had gonads with intratesticular oocytes. This highlights the occurrence of intersexual cases and suggests that at this size, the fish is susceptible to phenotypic plasticity. The results of the present study show that sexual differentiation of the gonads is found in fish at 4.5 g weight. The ambiguous relationship between the observed gonad morpho-functional characteristics and fish size suggests a subject-dependent sexual differentiation.