Comparison of the API 20E and BBL Crystal E/NF Identification Systems for Differentiating Bacterial Isolates from Apparently Healthy Reared Sea Bass (Dicentrarchus labrax)

The ability of two commercial rapid identification systems, API 20E and BBL Crystal E/NF, to reliably identify bacterial isolates from the internal organs of reared sea bass were compared. The tests gave different results: API 20E identified bacteria as Pseudomonas spp. with 37% accuracy, while BBL Crystal E/NF identified them as Flavobacterium odoratum with 99% accuracy. Although F. odoratum is not a marine fish pathogen, conventional tests conducted with the same isolates were more indicative of them being Flavobacterium spp. than Pseudomonas spp., suggesting that BBL Crystal E/NF was more reliable in this identification. Both systems were found to be applicable for diagnostics of marine fish pathogens, but should be used with caution because of possible misinterpretation.     

Age-related changes in hematology and plasma chemistry values of hybrid striped bass (Morone chrysops X Morone saxatilis)

Hybrid striped bass (Morone chrysops X Morone saxatilis ) are an important aquaculture species yet there are few diagnostic tools available to assess their health. Hematology and clinical chemistry analyses are not used extensively in fish medicine due to the lack of reference intervals for various fish species, and because factors such as age can affect blood values. There is little published information regarding age-related changes in blood values of juvenile fish. It is important to evaluate juvenile fish, as this is the time they are raised in aquaculture settings. Determining age-related changes in the blood values of fishes would further develop clinical pathology as a diagnostic tool, enhancing both fish medicine and the aquaculture industry. The results of standard hematology and clinical chemistry analysis were evaluated in juvenile hybrid striped bass at 4, 6, 9, 15, and 19 months of age. Values for PCV and RBC indices were significantly lower, and plasma protein concentration was significantly higher in younger fish. Total WBC and lymphocyte counts were significantly higher in fish at 6 and 9 months of age, while neutrophil and monocyte counts were higher at 6, 9, and 15 months. Eosinophil counts were significantly higher in 9-month-old fish. The majority of hematologic values fell within previously established reference intervals, indicating that only slight modification to the intervals is necessary for evaluating hematologic results of hybrid striped bass at different ages. The following analytes deviated sufficiently from adult reference intervals to warrant separate reference values: plasma protein concentration at 4 months, WBC and lymphocyte counts at 15 and 19 months, and thrombocyte-like-cells at 9 months of age. Values for most biochemical analytes were significantly different among age groups except for creatinine and potassium concentrations. Comparisons with reference intervals were not made for biochemical analytes, because established reference intervals were not available. Age-related changes in hematologic and biochemical values of striped bass were similar to those reported for rainbow trout and mammals.     

Dispersal of black sea bass (Centropristis striata) larvae on the southeast U.S. continental shelf: results of a coupled vertical larval behavior – 3D circulation model

In the marine environment, pelagic dispersal is important for determining the distribution and abundance of populations, as well as providing connections among populations. Estimates of larval dispersal from spawning grounds are important to determining temporal and spatial patterns in recruitment that may have significant influences on the dynamics of the population. We present a case study of the dispersal of Centropristis striata (black sea bass) larvae on the southeast U.S. continental shelf. We use a coupled larval behavior – 3D circulation model to compare the effects of the timing and location of spawning against that of larval vertical migration on larval dispersal. Using the results of field data on larval vertical distributions, we compare the dispersal of virtual 'larvae' which have ontogenetic changes in vertical behavior with that of particles fixed near the surface and near the bottom. Larvae were released at potential spawning sites four times throughout the spawning season (February through May) for 3 yr (2002–04) and tracked for the assumed larval duration (from 27 to 37 days including the egg stage). Results indicate that adult behavior, in the form of spawning time and location, may be more important than larval vertical behavior in determining larval dispersal on the inner- and mid- continental shelves of this region.     

Feed discrimination and selection in self-fed European sea bass Dicentrarchus labrax L.

Abstract This study was conducted to evaluate feed discrimination and preference of European sea bass Dicentrarchus labrax L., taking into account the effects of feed location, previous feeding experience and light conditions. Fish (63 g) were held in tanks and exposed to a 12L:12D photoperiod and ambient temperature. The following feeding practices were applied in triplicate: three‐choice feeding (self‐ feeding with feeds formulated for carnivorous, herbivorous and omnivorous fish rotated on a weekly basis) and monofeeding (self‐feeding with one of these feeds). After 9 weeks (phase I), fish previously held in monofeeding, were subjected to three‐choice feeding for 2 weeks (phase II). In phase I, fish discriminated between feeds after their rotational displacements and preferred the feed formulated for carnivorous species. This also supported the best growth. Fish used in phase II preferred the same feed. There was no preference for any location within tanks. Feeding was generally diurnal, although in some tests with the feeds for herbivores and omnivores, diurnal and nocturnal feed demands were similar and fewer in number than with the feed formulated for carnivores.     

Digestibility of nutrients and amino acids of different protein sources in practical diets by largemouth bass Micropterus salmoides (Lacepéde, 1802)

This study evaluated the apparent digestibility coefficients (ADCs) of dry matter, protein, lipid, energy, calcium, phosphorus, and essential and non‐essential amino acid availability of animal and plant protein sources in practical diets for the carnivorous fish, largemouth bass Micropterus salmoides (8.0±0.5 g; 10.0±0.3 cm). Fish were conditioned to accept artificial feed and those stocked in plastic cages were fed pelleted test diets. Diets contained 30% of the ingredient tested mixed with 70% of a reference ration (RD) containing 40 g 100 g^?1 of crude protein, 19.85 kJ g^?1 crude energy, and 0.5% of chromic oxide. Cages were then transferred to cylindrical, conical‐bottomed aquaria (200 L) where the faeces were collected by sedimentation in a refrigerated container. All the tested ingredients had high ADCs for protein and lipid; ADCs of amino acids of varying protein sources showed significant differences (P<0.01). Plant protein sources did not significantly influence the ADCs of diets. The results allow the inference that the availability of amino acids in plant and animal protein sources varies considerably.     

Immune response of sea bass <Emphasis Type="Italic">Dicentrarchus labrax</Emphasis> to <Emphasis Type="Italic">Tenacibaculum maritimum</Emphasis> antigens

ABSTRACT:   Seawater fishes are affected by a pathology commonly called 'myxobacteriosis', caused by Tenacibaculum maritimum (formerly Flexibacter maritimus ). The disease is characterized by fin erosion and necrotic ulcers of skin and muscle, and by low but constant mortality in cultured marine fish; in Italy is one of the most important and widely spread diseases affecting sea bass Dicentrarchus labrax , gilthead seabream Sparus aurata , sharp-snouted bream Diplodus puntazzo , white bream Diplodus sargus , and six-tooted bream Dentex dentex . In order to obtain an effective vaccine against the disease, formalin killed cells (FKC), extracellular products (ECPs) and crude lipopolysaccharide (LPS) preparations were obtained from the T. maritimum strain SPVId and injected intraperitoneally twice into the sea bass. The fish immune response to the preparations was studied: agglutinating antibody titer and in vitro phagocytosis were determined after the first and second injection in order to evaluate whether the preparations are immunogenic or not and if the booster effect took place. The results show that FKC and LPS preparations increased the antibody titer after the first injection when compared to the control sea bass. Moreover, all the preparations stimulated a secondary (booster) response. In vitro phagocytosis of the total blood was significantly higher for all the preparations when compared to the controls, but the crude LPS immunized sea bass showed the highest activity.     

Dietary spermine supplementation induces intestinal maturation in sea bass (Dicentrarchus labrax) larvae

Sea bass (Dicentrarchus labrax) larvae were fed microparticulated compound diet containing 0 (FP0), 0.10 (FP10) and 0.33% (FP33) of a polyamine, spermine, from day 20 to day 38. LP group was fed live prey. This group exhibited the highest growth and survival. The addition of spermine did not lead to growth enhancement. A 33% survival improvement was obtained in FP33 group compared to FP0 group. The spermine addition affected the activity of pancreatic enzymes, trypsin, chymotrypsin and amylase, during larvae development. This non specific effect suggested that the action of spermine would be mediated by hormones. In the intestine, the FP33 group exhibited from day 31 higher activities of brush border membrane enzymes (leucine aminopeptidase and alkaline phosphatase) and lower level in a cytosolic enzyme (leucine-alanine peptidase) compared to FP10 and FP0 group. The diet containing the highest spermine level induced an enzymatic profile similar to that obtained in LP group and characteristic of a mature enterocyte. The initiation of enterocyte maturation at a proper development stage was associated to the survival improvement observed in FP33 group.     

Production of meiotic gynogenetic and triploid sea bass, Dicentrarchus labrax L.: 1. Performances, maturation and carcass quality

Meiotic gynogenetic and triploid sea bass were produced by pressure shocks according to a previously published protocol. Pressure-treated groups did not survive as well as controls during early development and larval rearing. Performances, sexual maturation and carcass quality were examined over a period of 34–45 months. At the age of 34 months, growth of the gynogenetic fish was comparable to that of the control but inferior in the triploid fish. A predominance of male fish was found within the triploid groups, while diploid and meiotic gynogenetic fish showed equal proportions of the sexes. Gonadal maturation in triploid fish was significantly impaired, particularly in the females that showed rudimentary ovaries. Triploid males exhibited primary maturation but proved to be gametically sterile. Pressure-induced triploids did not grow as well as diploids, but these results might be ascribed to specific on-growing conditions (communal rearing). The performance of gynogenetic sea bass was comparable to that of control. The superiority of diploid fish over their triploid counterparts was confirmed during the final growing period and more clearly so in females. Performances of triploids varied according to their maternal origin. Overall, striking qualitative differences between diploid and triploid fish were found at the age of 34 and 45 months, although the results varied in a gender-specific manner. A strong maternal effect was also observed. The potential advantages of triploid sea bass for aquaculture purposes are discussed.     

饲料中维生素K3含量对大口黑鲈消化能力、血清代谢指标、肌肉氨基酸和脂肪酸组成的影响

为研究饲料中维生素K₃含量对大口黑鲈消化能力、血清代谢指标、肌肉氨基酸和脂肪酸组成的影响,在基础饲料中分别添加不同水平的维生素K₃,配制成维生素K₃含量分别为0.78(K0组)、5.80(K5组)、10.82(K10组)、15.84(K15组)和20.85 mg/kg(K20组)的5种试验饲料,对初均重为(12.96±0.07)g健康大口黑鲈幼鱼进行为期8周的饲养试验。结果表明:添加维生素K₃的各组胃和肠道的蛋白酶、淀粉酶和脂肪酶活性均显著低于K0组(P<0.05)。K10组、K15组和K20组的表观消化率和蛋白质表观消化率显著低于K0组(P<0.05)。K20组的血清尿素氮含量显著高于其他4组(P<0.05),血清总蛋白、白蛋白、总胆固醇和甘油三酯含量在各组之间无显著差异(P>0.05)。肌肉必需氨基酸、非必需氨基酸和总氨基酸含量以及必需氨基酸指数在各组之间无显著差异(P>0.05),但是随着饲料中维生素K₃含量的增加,必需氨基酸和总氨基酸含量呈增加的趋势。K15组的肌肉单不饱和脂肪酸含量显著高于其他4组(P<0.05),其中C16∶1n7和C18∶1n5含量均较其他组显著升高(P<0.05)。肌肉饱和脂肪酸和多不饱和脂肪酸含量在各组之间无显著差异(P>0.05)。综上可知,饲料中添加维生素K₃可以改善大口黑鲈肌肉氨基酸组成,但当饲料中维生素K₃含量≥5.80 mg/kg时会使大口黑鲈的消化能力下降,并且高剂量的维生素K₃会改变大口黑鲈的蛋白质和脂质代谢。