The kinetic profile of oxolinic acid in sharpsnout sea bream, Diplodus puntazzo (Cetti 1777)

The pharmacokinetics of oxolinic acid (OA) were investigated after a single intra‐vascular injection (20 mg kg^?1 fish) in sharpsnout sea bream (90 g), a promising new euryhaline species for Mediterranean fish farming. The distribution half‐life (t_1/2α) and the elimination half‐life (t_1/2β) of OA were calculated to be 0.4 and 10 h respectively. The apparent volume of distribution at steady‐state (V_d(ss)) and total clearance rate (CL_T) of the drug were found to be 2.1 L kg and 0.2 L kg^?1 h^?1 respectively. The bioavailability (F%) of OA following oral administration (40 mg kg^?1 fish) was estimated to be 15%. The results indicate a rapid distribution and elimination of the drug, moderate tissue penetration, but low absorption in sharpsnout sea bream. The kinetic profile of OA found in this species is comparable with that observed in another well‐known sparid, gilthead sea bream.     

Sensory evaluation of farmed sharpsnout seabream (Diplodus puntazzo)

The first attempts at applying aquacultural techniques to sharpsnoutseabream (Diplodus puntazzo) have proved very promising.One of the factors to keep in mind when analysing the viability of a speciesforindustrial farming is that of consumer acceptance of the product, a variablethat can be measured by sensory evaluation tests. To that end, 107 participantsfrom a number of work centres were assessed with hedonic sensory tests usingsharpsnout seabream samples. For reference purposes, the tasting also includedgilthead seabream samples. Participants were asked to fill out a questionnairethat included questions concerning their preferences for any one fish. Weanalysed the sensory attributes of both fish species using a hedonic scale, andalso their acceptability (disposition to purchase) to consumers. The resultsproved fairly encouraging with a view to sharpsnout seabream large-scaleproduction. All attributes tested in the sensory profile analysis werepositively rated. About 60% of the surveyed population would consider buyingsharpsnout seabream at a price similar to that of gilthead seabream (10),and 85% found it to be pleasing to the eye. Aside from flavour, its texture,juiciness and fat level are the most important appraisal attributes. Efforts toimprove the organoleptic characteristics of the species should focus mainly onthese attributes.     

Sensory evaluation of farmed sharpsnout seabream (Diplodus puntazzo)

The first attempts at applying aquacultural techniques to sharpsnoutseabream (Diplodus puntazzo) have proved very promising.One of the factors to keep in mind when analysing the viability of a speciesforindustrial farming is that of consumer acceptance of the product, a variablethat can be measured by sensory evaluation tests. To that end, 107 participantsfrom a number of work centres were assessed with hedonic sensory tests usingsharpsnout seabream samples. For reference purposes, the tasting also includedgilthead seabream samples. Participants were asked to fill out a questionnairethat included questions concerning their preferences for any one fish. Weanalysed the sensory attributes of both fish species using a hedonic scale, andalso their acceptability (disposition to purchase) to consumers. The resultsproved fairly encouraging with a view to sharpsnout seabream large-scaleproduction. All attributes tested in the sensory profile analysis werepositively rated. About 60% of the surveyed population would consider buyingsharpsnout seabream at a price similar to that of gilthead seabream (10∈),and 85% found it to be pleasing to the eye. Aside from flavour, its texture,juiciness and fat level are the most important appraisal attributes. Efforts toimprove the organoleptic characteristics of the species should focus mainly onthese attributes.     

Mono- and duoculture of juvenile sharpsnout seabream Diplodus puntazzo (Cetti) and gilthead seabream Sparus aurata L. in a recirculated water system

Although the growth of intensively reared sharpsnout seabream Diplodus puntazzo (DP) has been suggested to improve in duoculture with gilthead seabream Sparus aurata (SA), the stocking ratio for most effective duoculture rearing has not been investigated. For this purpose, juvenile D. puntazzo (1.68±0.011 g) and S. aurata (1.43±0.007 g) were reared in duplicated groups of 165 specimens each, in two monoculture (100% DP, 100% SA) and four duoculture combinations (80% DP–20% SA, 60% DP–40% SA, 40% DP–60% SA, 20% DP–80% SA) for 96 days under recirculated water system conditions. Both species exhibited the highest growth when stocked at 20% and the poorest growth when stocked at 80%. For each species, no major differences for coefficient of weight variation and carcass proximate composition were detected. As the percentage of stocked S. aurata increased, D. puntazzo aggressiveness and weight variability of whole population were reduced, while total biomass, food consumption and food conversion ratio were increased. The results obtained are discussed in relation to fish behaviour and social interactions. From the fish farming point of view, it is indicated that under the present experimental conditions, juvenile S. aurata should be reared in monoculture and D. puntazzo in duoculture 40% DP–60% SA.     

Aspects of the reproductive biology of the sharpsnout seabream Diplodus puntazzo (Cetti, 1777). I. Gametogenesis and gonadal cycle in captivity during the third year of life

A histological study was made of the reproductive cycle of captive sharpsnout seabream Diplodus puntazzo during the 3rd year of life. All specimens contained both ovarian and testicular tissue. Ovarian tissue prevailed in 64 out of 120 fish sampled throughout one year. The ovary underwent a long resting phase from October to August, during which time it contained oogonia, primary growth phase (PGP) and occasional yolk vesicle stage oocytes. Intense ovarian development took place in September leading to the formation of advanced vitellogenic oocytes. Final maturation and spawning were not achieved in any of the fish. The testicular area in the predominantly female gonads contained only spermatogonia and was found to be histologically normal in 76% of individuals, but severely regressed in the remaining fish. The testicular portion was found to be dominant in 56 out of 120 fish sampled throughout one year. These underwent a resting phase from November to July, a maturing/pre-spawning phase in August, and a spawning phase with spontaneous sperm release in September to October, as in the natural environment. The ovarian portion in the functional male gonads contained only oogonia and oocytes which did not develop beyond the perinucleolus stage at any point during the reproductive cycle. Apart from the pre-spawning/spawning phase, during which the gonadosomatic index (GSI) was comparable in the two groups, the GSI values were approximately ten-fold higher in those fish in which the ovary predominated than in those in which the testis predominated.     

Effect of feeding rate on fatty acid composition of sharpsnout seabream (Diplodus puntazzo)

The effects of different feeding rates on the lipids fatty acid profile of sharpsnout seabream (Diplodus puntazzo) tissues were studied. During a 15‐day period, four fish groups were allowed to feed to satiation, at two‐thirds and one‐third of satiety, and starved, respectively. Reducing food intake progressively increased the n‐3:n‐6 relationship by increase of n‐3 (mainly Highly Unsaturated Fatty Acids) and decrease of n‐6 fatty acid percentages. In perivisceral fat, this n‐3:n‐6 value was already statistically significant lower for the group fed to satiety (1.29 versus 1.71, 1.80 and 1.65 for the two‐third‐fed, one‐third‐fed and fasted groups, respectively), whereas in the white muscle (1.69 versus 2.13 and 2.12) and liver (0.83 versus 1.40 and 2.66) the differences were statistically significant only for the one‐third‐fed and fasted groups. Linoleic acid was the main contributor to the n‐6 drop, whereas the n‐3 fatty acids preferentially preserved were for the most part essential fatty acids. Fat quality indices (thrombogenic and atherogenic) were not affected by food restriction except for liver, being the former significantly lower in the one‐third‐fed and fasted groups. Food intake restriction to one‐third of satiety levels was enough to trigger the mechanisms that preserve essential fatty acids.     

Dietary self-selection in sharpsnout seabream (Diplodus puntazzo) fed paired macronutrient feeds and challenged with protein dilution

Macronutrient selection and responses to dietary protein dilution were investigated in 95-g sharpsnout seabream, an omnivorous fish species of interest for Mediterranean aquaculture. Five groups of 18 sharpsnout seabream were distributed among circular 450-l tanks and allowed to self-feed from 3 feeders each of which distributed feeds composed of different pairs of macronutrients: PC (75% protein, 25% carbohydrate), PF (75% protein, 25% fat) or FC (50% fat, 50% digestible carbohydrate). Regardless of self-feeders position, the fish composed a diet containing 63% protein, 19% fat and 18% carbohydrate. When the protein-containing diets (PC and PF) were diluted 50% with cellulose, the fish increased their food intake to compensate for the energy dilution (170 kJ/kg BW/day vs. 168 kJ/kg BW/day after dilution), and dietary composition (63% protein, 16% fat and 21% carbohydrate) did not change significantly. These results demonstrate that sharpsnout seabream can select from incomplete diets to compose a balanced diet, and the fish are also able to compensate for a dietary dilution to regulate both energy intake and the relative proportions of macronutrients.     

A study of the pattern of digestive enzymes in Diplodus puntazzo (Cetti, 1777) (Osteichthyes, Sparidae): evidence for the definition of nutritional protocols

The digestive enzymes (proteases, carbohydrases and lipases) present along the alimentary tract of juveniles and adults of Diplodus puntazzo were studied. The data obtained showed a different distribution of the enzymatic activities in the different parts of the alimentary tract. Levels of enzymatic activity in the adults were higher than those measured in juveniles, suggesting that adults have a greater ability to digest larger pieces of food. The enzymatic pattern of D. puntazzo justifies its omnivorous habit and suggests an high potential for digesting vegetable polysaccharides. The results of this study suggest the need to adapt the diet to the digestive potential of this new farming species, thus contributing to the attainment of a product that is qualitatively more similar to the wild one.     

Meristic character counts and incidence of skeletal anomalies in the wild Diplodus puntazzo (Cetti, 1777) of an area of the south-eastern Mediterranean Sea

The sharpsnout seabream (Diplodus puntazzo, Cetti 1777) is a species rarely found in coastal areas of Sicily, but is important in Mediterranean aquaculture. In order to detect the number of meristic characters and the main types of body deformation, 588 specimens of sharpsnout seabream were collected from a coastal zone of south-east Sicily (Licata, AG—Italy). Different sized classes were examined and the relationship between size and the number of meristic characters (number of fin rays) was found. The number of vertebrae, anal fin hard rays and dorsal fin hard rays was constant and did not vary with size. Seventeen types of skeletal and fin anomalies were observed, but no grave anomalies were found, such as the absence of a swimbladder, lordosis, kyphosis and calculi in the terminal tract of the urinary duct. The most prevalent anomalies were associated with the fins, especially E7 (pectoral fin rays), F7 (anal fin rays) and I7 (dorsal fin soft rays). There was no correlation between frequency of anomaly and size class. The malformation index was 4.54.     

Chronic ulcerative dermatopathy in cultured marine fishes. Comparative study in sharpsnout sea bream, Diplodus puntazzo (Walbaum)

Chronic ulcerative dermatopathy (CUD) also known as chronic erosive dermatopathy, hole-in-the-head, head and lateral line erosion syndrome (HLLE) and lateral line depigmentation (LLD) is a chronic disease of unknown aetiology that affects the lateral line canals of the head and the trunk of various fish species. It has been described only in freshwater species although there are reports that it also affects marine fish. Here, we describe the disease in cultured sharpsnout sea bream using histology and scanning electron microscopy and identify several marine species as CUD sensitive. The results of this study correlate the development of the disease with the use of borehole water, indicating that the aetiology is probably associated with water quality rather than nutritional imbalance or infectious agents.     

Phenotypic effects of antibiotic‐induced axenity and egg disinfection in early larval European seabass (Dicentrarchus labrax L.)

In the present study, the hypothesis that the difference in axenic conditions in the incubation and rearing environment of European seabass larvae induces size and shape effects on the specimens is tested. This difference is studied between xenic and axenic seabass larvae of DAH (day after hatching) 0, 5, 11 and 15. The axenic rearing protocol involves an egg disinfection with glutaraldehyde after the primary one with iodine in the hatchery, and the hypothesis that this secondary disinfection induces size and shape effects is also tested. In order to accomplish this, three egg and larvae treatments are included: “DA” (disinfected axenic), “DX” (disinfected xenic) and “NX” (nondisinfected xenic). Regarding the effect of antibiotic‐induced axenity, DA larvae exhibited larger bodies than both DX and NX on DAH 5 and 11. They also had a smaller yolk sac than DX at hatching, but consumed it slower. Towards the end of the experiment, DA larvae were thicker, but slightly more curved than DX and NX, which may be an abnormal shape, or a slightly more advanced ontogenetic stage. As far as egg disinfection, it had significant but very moderate shape effects on DAH 5 and 11, and disinfected larvae consumed their yolk sac faster. To the best of our knowledge, this study is one of the first to illustrate the subtle but significant size and shape effects caused by antibiotic‐induced axenity and secondary egg disinfection in the early larval stages, which suggest the existence of bacterial mechanisms that play a phenotypic role.     

Effects of antibiotic‐induced differences in bacterial load on growth and shape of early larval European seabass (Dicentrarchus labrax L.)

The aim of the present study was to quantify the effects of antibiotic‐induced differences in bacterial load on the size and shape of fish larvae, using Dicentrarchus labrax of day after hatching (DAH) 3 as a case study. They were split in two treatment groups and reared in 50 ml vials until DAH 14, with the control treatment (“NA”) including larvae reared in filtered autoclaved seawater without antibiotics, while the second (“A”) included larvae reared in filtered autoclaved seawater with rifampicin, ampicillin, kanamycin, trimethoprim and gentamicin, with a concentration of 10 mg/L each. They were sampled for bacterial presence on DAH 4, 7 and 14, and had their mortalities recorded, their total lengths, gut lengths, anal body depths, eye diameters, head depths, yolk sac lengths and yolk sac depths measured, and their outlines analysed on DAH 7 and 14. Treatment NA exhibited the highest mortalities on DAH 14. The antibiotics had a significant size effect, yielding larvae with larger total length on DAH 7 and 14, larger bodies on DAH 7, and on DAH 14 larger anal body depth and greater variance in body size. Their effect on outline shape was also significant in both age classes, with increasing differences from DAH 7 to DAH 14. On DAH 7, “A” specimens were more uniform in their dorso‐ventral development, and on DAH 14 “NA” had more slender shapes. The beneficial total length and size effects and the witnessed shape effects might be associated with the low bacterial presence.     

Body shape variation within and among three species of darters (Perciformes: Percidae)

Abstract –  Using geometric morphometric (GM) techniques, we quantified intra and interspecific variation in female body shape using five collections each of Etheostoma caeruleum Storer, Etheostoma nigrum Rafinesque, and Etheostoma stigmaeum (Jordan). Nested multivariate analysis of variance showed significant variation in body shape among populations (Wilks' Λ = 0.0687, F _144,7585.1 = 19.35, P  < 0.0001), as well as among species (Wilks' Λ = 8.7 × 10⁻⁶, F _24,2 = 28.18, P  = 0.0348). Etheostoma caeruleum displayed greater body depth relative to both E. nigrum and E. stigmaeum , whereas E. nigrum displayed a compressed arrangement of mid-body landmarks relative to both E. stigmaeum and E. caeruleum . The broader implications of these findings highlight the value of geometric morphometrics as both an exploratory and analytical approach. Conclusions drawn from comparisons among moderately differentiated darter species in future studies of body size and shape are likely robust to intraspecific variation within species, and will permit more rigorous investigations into the ecomorphology of these benthic stream fishes.     

Fish oil substitution by soybean oil in Sharpsnout seabream Diplodus puntazzo: Performance,fatty acid profile,and liver histology

The present study was conducted to determine the effect of soybean oil on the performance and liver histology in Sharpsnout seabream (Diplodus puntazzo) (initial body mass 35 g). Four experimental diets were formulated containing 0%, 25%, 50%, and 75% of soybean oil substituting fish oil. Fish were fed for 84 days. Increasing the level of soybean oil had no significant effects on growth and feed efficiency parameters. Biometrics, body composition, protein efficiency, and energy efficiency were not affected by the fish oil replacement. Muscle and liver fatty acids reflected fish oil substitution. Moreover, histology did not show statistical differences among treatments. Sharpsnout seabream juveniles can be fed with diets in which fish oil has been replaced with soybean oil at up to 75% of total lipid in the diet for a period of 84 days without affecting growth, feed efficiency, biometric parameters, and body composition.     

Morphoecology in larval fin-fish: a new candidate species for aquaculture, Diplodus puntazzo (Sparidae)

This study was aimed to acquire information ontrophic behavior of Diplodus puntazzolarvae and juveniles, by studing theontogenetic sensory development, except vision.D. puntazzo specimens were observed usinga scanning electron (n = 67) and a lightmicroscope (n = 7). The results concerned fourontogenetical stages of sharpsnout seabream:larval, post-larval, transitional, and juvenilestages. The yolk-sac larval stage was notdetected as the smallest larvae at our disposal(3.1 mm TL; 2nd day from hatching) showedno external appearance of the yolk. During thelarval stage (3.1–4.7 mm TL), sharpsnoutseabream is equipped with free neuromasts andolfactory ciliated receptor cells. In thepost-larval stage (5–28.6 mm TL), mechano- andchemo-reception is implemented: the inner andouter taste buds differentiation, the nasalformation, the lateral line system canalizationoccur. The precocious differentiation ofchemo-receptors makes post-larvae particularlysensitive to the organoleptic properties ofadministered preys. D. puntazzo, at theend of this phase, could be considered ajuvenile (complete squamation is acquired),except for the mouth and pharyngeal teeth.During the subsequent phase (`transitional'),in fact, eight chisel-type and two lateralseries of molar-like teeth progressivelysubstituted the conical ones on each jaw, andthree different types of teeth on the upper andlower pharynx differentiated. So, the juvenilephase is reached in individuals longer than58 mm TL.     

Body shape variation in two species of darters (Etheostoma,Percidae) and its relation to the environment

Environmental variation can shape phenotypic variation in organisms, but most evidence for trait differentiation comes from analyses of dichotomous habitat types that differ in only one or few key environmental factors. In reality, environmental variation is often more subtle, gradual and multifarious. Here, we investigated geographic variation in body shape of two darter species (Etheostoma spectabile and Etheostoma flabellare; Percidae) that occur along river gradients. This study addressed three specific questions: Is there intraspecific geographic variation in the two species across different sites in the Ozark Highlands of Oklahoma (USA)? Is phenotypic variation across sites correlated with abiotic environmental conditions? Do the two species share site‐specific (i.e. convergent) phenotypic variation in areas where they occur together? Our results indicated significant body shape variation in both species. Population differences in body shape were particularly correlated with variation in substrate composition. The combined analysis of both species indicated a small but significant effect of convergence on body shape wherever they are sympatric; shared variation, however, was not related to any environmental variables included in the analysis. While it remains unclear whether phenotypic variation in these species is due to heritable differentiation or environmentally induced plasticity, our results indicate that even subtle and gradual environmental variation can induce substantial variation in phenotypes on a relatively small spatial scale.