Diplodus Puntazzo Research Articles

Severe mortality in mesocosm-reared sharpsnout sea bream Diplodus puntazzo larvae due to epitheliocystis infection

This paper describes severe mortalities recorded in sharpsnout sea bream Diplodus puntazzo larvae reared in mesocosms. The mortalities were attributed to epitheliocystis infection. The pathology associated with the disease is described using histological techniques. Microscopical examination showed a massive infection of the skin, fins, and oral cavity, with impaired feeding, respiration, and osmoregulation being the most likely cause of death. This is the first report of epitheliocystis disease in sharpsnout sea bream and in fish at such an early developmental stage.

Ontogeny of the digestive tract in sharpsnout sea bream Diplodus puntazzo (Cetti, 1777).

The ontogeny of the digestive tract was studied histologically and histochemically in sharpsnout sea bream Diplodus puntazzo from hatching (0 DAH, Days After Hatching) until day 57 (57 DAH). At hatching, the digestive tract appeared as a histologically undifferentiated straight tube lying dorsally to the yolk sac. When the mouth opened at 3 DAH, the digestive tract was differentiated into buccopharynx, oesophagus, incipient stomach and intestine. The pancreas, liver and gall bladder were also differentiated at this stage and both the bile and pancreatic duct had opened into the anterior intestine. Active feeding began in 50% of larvae at 4 DAH, although permanence of yolk reserves until 7 DAH suggests a period of both endogenous and exogenous feeding. Nutrient absorption was first visible from 5 DAH, as colourless supra- and infranuclear vacuoles in the anterior intestinal mucosa, suggesting a lipid content, as well as supranuclear, eosinophilic vacuoles, containing protein, in the posterior intestinal mucosa. Early caecal development could be detected from 10 DAH, whereas gastric glands appeared at 30 DAH, indicating the transition from larval to juvenile stage and the acquisition of an adult mode of digestion. Goblet cells appeared in the digestive tract of sharpsnout sea bream larvae shortly after first feeding. The mucus content of goblet cells varied with the digestive region and, in the buccal cavity and oesophagus, also with the developmental phase. This study provides knowledge for better husbandry practices in the aquaculture industry, as well as for the implementation of future nutritional studies.

Morphometric characterization of sharpsnout sea bream (Diplodus puntazzo) and gilthead sea bream (Sparus aurata) spermatozoa using computer-assisted spermatozoa analysis (ASMA)

As part of a larger study on sperm quality and cryopreservation methods, the present study characterized the head morphometry of sharpsnout sea bream (Diplodus puntazzo) and gilthead sea bream (Sparus aurata) spermatozoa, using both scanning electron microscopy (SEM) and computer-assisted morphology analysis (ASMA). The latter method has been used rarely in fish and this is its first application on sharpsnout sea bream and gilthead sea bream spermatozoa. Results obtained using SEM are expensive and time-consuming, while ASMA provides a faster and automated evaluation of morphometric parameters of spermatozoa head. For sharpsnout sea bream spermatozoa, similar head measurement values were obtained using both ASMA and SEM, having a mean ± standard error length of 2.57 ± 0.01 μm vs 2.54 ± 0.02 μm, width of 2.22 ± 0.02 μm vs 2.26 ± 0.04 μm, surface area of 4.44 ± 0.02 μm2 vs 4.50 ± 0.04 μm2 and perimeter of 7.70 ± 0.02 μm vs 7.73 ± 0.04 μm using ASMA and SEM, respectively. Although gilthead sea bream spermatozoa were found to be smaller than those of sharpsnout sea bream, spermatozoal head morphometry parameters were also found to be similar regardless of evaluation method, having a mean head length of 1.97 ± 0.01 μm vs 1.94 ± 0.02 μm, head width of 1.80 ± 0.01 μm vs 1.78 ± 0.02 μm, surface area of 3.16 ± 0.03 μm2 vs 3.18 ± 0.06 μm2 and perimeter of 6.52 ± 0.04 μm vs 6.56 ± 0.08 μm using ASMA and SEM, respectively. The results demonstrate that ASMA can be considered as a reliable technique for spermatozoal morphology analysis, and can be a useful tool for studies on fish spermatozoa, providing quick and objective results.

SHELF LIFE OF NEW CULTURE SPECIE (DIPLODUS PUNTAZZO) IN REFRIGERATOR

ABSTRACT The shelf life of sharp snout sea bream (Diplodus puntazzo) stored in refrigerator was investigated by measurement of sensory, chemical (total volatile basic nitrogen [TVB‐N], trimethylamine [TMA‐N], thiobarbituric acid [TBA] and pH) and microbiological (total viable and psychrophilic count) analysis. According to the sensory and chemical analysis results evaluated, the shelf life of sharp snout sea bream was detected as 10 days for storage at refrigeration temperatures, respectively, as compared with 8 days of sensory analysis results.PRACTICAL APPLICATIONSSharp snout sea bream is one of the important fish species in the aquaculture sector in Turkey. In recent years, the aquaculture sector was mainly interested with the fish species Dicentrarchus labrax and Sparus aurata, but nowadays, a new valuable fish aquaculture is possible in this sector. Diplodus puntazzo, Dentex dentex and Sciena umbra are some of them. The importance of this study came from being the first in the literature that determines the shelf life for these species.

Ultrastructure of Enteromyxum leei (Diamant, Lom, & Dyková, 1994) (Myxozoa), an Enteric Parasite Infecting Gilthead Sea Bream (Sparus aurata) and Sharpsnout Sea Bream (Diplodus puntazzo)

The ultrastructure of the developmental stages of the myxozoan Enteromyxum leei parasitizing gilthead seabream (Sparus aurata) intestine and sharpsnout sea bream (Diplodus puntazzo) intestine and gallbladder are described. The earliest stage observed was a small dense trophozoite located among enterocytes. Proliferative stages, observed intercellularly in the epithelium of the intestine and gallbladder as well as in the lumen, possessed the typical cell-in-cell configuration throughout their development. Secondary cells were seen undergoing division within a common vacuolar membrane that also encompassed pairs of tertiary cells. Cytochemical studies showed that primary cells stored mainly lipids whereas secondary cells stored abundant beta-glycogen granules. Sporogonic development resembled that described for other disporous myxozoans. Within sporogonic stages, nonsporogonic secondary cells were observed accompanying two developing spores. Mature spores had a binucleated sporoplasm in which glycogen stores were abundant and no sporoplasmosomes were found. Our observations are discussed in relation to our knowledge on other myxozoans of the genus Enteromyxum.

Egg and sperm production and quality of sharpsnout sea bream (Diplodus puntazzo) in captivity

Egg production from captive-reared sharpsnout sea bream (Diplodus puntazzo) was monitored during the spawning seasons of 2003 to 2005, and sperm production during 2003. Spawning took place between September and December under water temperatures of 21.0–18.5 °C. Daily fecundity varied without a consistent trend and peak egg production occurred in October. Mean (±S.E.M.) number of spawning days per month was 20±3 in 2003, and 14±3 in 2004 and 2005. A significant (ANOVA, DNMR, P<0.01) drop was observed in mean total annual relative fecundity from 4.9±0.08 million eggs kg−1 female body weight in 2003, to 2.4±0.07 million eggs kg−1 in 2004 and 2005. Mean monthly fertilization success also dropped significantly from 81±1% in 2003 to 76±2% in 2004 and 78±2% in 2005. Annual hatching success did not vary significantly and was around 86±2%. Finally, 5 day larval survival decreased significantly from 85±2% in 2003 to 44±3% in 2004. The first spermiating males were found in August and sperm production continued until December. Mean total volume of expressible sperm was maximal in November (3±1 ml kg−1) and the gonadosomatic index (GSI) ranged between 0.6 and 2.0% in spermiating fish, reaching its peak in September–November. Sperm motility (%) remained unchanged during the season, whereas motility duration (6.2±1.7 min) and sperm density (2.7±0.2×1010 spermatozoa ml−1) peaked in October. Mean sperm survival ranged between 9 and 13 days during most of the spawning season, and decreased significantly to 5 days in December. The study suggests that egg production is stable for the first 3 months of the spawning season, with relatively unchanged egg quality. On the contrary, sperm production and quality peaks in the middle of the reproductive season in October.

Egg quality determination based on the shape of the lipid vesicle in common dentex, Dentex dentex

The shape of the lipid vesicle (the ratio between the maximal and the minimal diameter and the shape coefficient) of the eggs of Diplodus puntazzo and Sparus aurata is correlated with larval survival rate (%) and can be used as an egg quality marker as reported previously by Lahnsteiner and Patarnello (2005). In the present study, this method for egg quality determination has also been validated for common dentex, Dentex dentex, after introducing several modifications in the calculation and evaluation procedure in order to obtain higher sensitivity. In the present study, it could be demonstrated that the shape of the lipid vesicle is not only correlated with the hatching rate but also with the survival rate of 1, 2 and 3 days post hatch larvae and therefore it can also be used as an indicator of larval viability at early stages of development.

Activity of the Digestive Protease, Chymotrypsin, in Larvae of the Cultured Sharpsnout Sea Bream (Diplodus puntazzo)

Specific and total activity of the digestive protease, chymotrypsin, was studied in cultured sharp- snout sea bream larvae (Diplodus puntazzo) for 35 days from hatching and in a variety of pH lev- els. Activity was detected upon hatching (2.8±0.34 mm total length), before the onset of exoge- nous feeding. Specific chymotrypsin activity exponentially increased from mouth opening on day 3 until day 25, then dropped until the end of the experiment. Total chymotrypsin activity sharply increased to day 10, then continued to increase, but slightly, until the end of the experiment. As expected, pH strongly affected both specific and total chymotryptic activity in the digestive tracts of larvae. Both were significantly lower when pH was acidic (1.5, 3.0, 4.0) than when it was alka- line (8.0, 9.0, 10.0) although there were no significant differences within either the acidic or the alkaline range. Our results indicate that chymotrypsin activity is capable of digesting protein before mouth opening and may be a valuable tool for better understanding the nutritional capa- bilities of young larvae.

Gonadal development and spawning cycle in the digynic hermaphrodite sharpsnout seabream Diplodus puntazzo (Sparidae) off the Canary Islands, northwest of Africa

Summary Diplodus puntazzo is a species characterized by a rudimentary hermaphroditism, with a low level of protandry. The study found that the overall sex ratio was one male to 2.03 females, diverging significantly from 1 : 1, and that there was a ratio of one male to 0.11 transitional fish. The sex ratio varied with season: during the reproductive period the ratio was 1 : 1.86 (male : female), significantly lower than in the non-reproductive period in which the sex ratio was approximately 1 : 2.26. Both sexes had similar size distributions; however, females were predominant in all size intervals, especially in the larger ones. No significant difference in mean total length (TL) between females (330 mm), males (319 mm) or transitionals (321 mm) was found. The smallest functional female and male analysed were 159 and 157 mm TL, and the largest were 520 and 510 mm TL, respectively. No significant difference in length at first level of maturity, attained at the second year of life, was found between males (281 mm) and females (292 mm), respectively. A protracted spawning season was identified for the species: from September to February, with a peak in November. GSI values followed the same pattern for males and females, with values of females being similar to those of males; the highest values occurred between September and December, with a maximum in November. Occurrence of transitional fish was significantly higher during the month with highest values of GSI than in the resting period. The study found that vitellogenesis did not begin synchronously for all females, and the simultaneous presence of oocytes in all stages of development indicated an asynchronous mode of ovarian development. The presence of postovulatory, together with tertiary yolk vesicle oocytes, indicated that the species is a multiple spawner.

Energy intake and macronutrient selection in sharpsnout seabream ( Diplodus puntazzo) challenged with fat dilution and fat deprivation using encapsulated diets

Sharpsnout seabream fed pure macronutrient capsules were challenged to fat dilution and fat deprivation in order to investigate the effects of fat level on energy intake regulation and macronutrient selection by fish, as they lack oropharyngeal chemosensory information from the diet. During the control phase, the fish were fed three individually encapsulated macronutrients, from which they composed a diet containing 67.36% protein (P), 19.08% carbohydrates (CH) and 13.57% fat (F), in terms of macronutrient weight intake percentage. During the second phase of the experiment, a lipid content reduction in F capsules from 55.0% to 13.4% did not significantly modify this selection pattern, energy ingestion or the number of capsules ingested of each macronutrient. During the third phase, in which they were subjected to fat deprivation, starting on almost the first day, the fish increased their total energy intake and total ingested number of capsules. These results reveal that fish are capable of distinguishing and selecting each of the three macronutrients contained in gelatine capsules, and that fish selection of a balanced diet from pure macronutrients is remarkably stable. Fish are capable of sustaining their macronutrient selection pattern and energy intake with very low amounts of fat in their diets (Phase 2). A certain instability in the initial P, CH and energy intake was only observed when fat was totally deprived (Phase 3), which resulted in higher values than those observed in Phase 1. In order to examine any possible effects of diet encapsulation, digestibility assays were performed in a second experiment. The fish were divided into two experimental groups and fed the same complete commercial diet, the only difference being the way it was presented to each group (pelleted or encapsulated). No statistical differences between the experimental groups were found with regards to both apparent digestibility coefficients and fish growth.

Histopathology and cellular response in Enteromyxum leei (Myxozoa) infections of Diplodus puntazzo (Teleostei)

Enteromyxum leei is an intestinal parasite responsible for serious outbreaks in Mediterranean sharpsnout sea bream Diplodus puntazzo. E. leei infection was experimentally transmitted to healthy D. puntazzo (R) by cohabitation with infected donor fish. Haematological changes and histopathological damage were evaluated in relation to the course of infection. The prevalence of infection in R fish was 100% from day 10 post-exposure (p.e.) onwards, and the infection intensity and histopathological damage increased progressively. Different developmental stages were found in the infected intestines, including proliferative (stages 1–3) and sporogonic (stages 4 and 5) stages. Intestinal damage consisted of vacuolation, necrosis, detachment and sloughing of epithelium, and was correlated with the progression of the infection and with the development of the parasite. Sporogonic stages appeared from day 20 p.e. onwards. Initially, D. puntazzo seems to counteract the infection through the increase in leucocyte numbers, respiratory burst activity, haematopoietic activity and MMC. Two types of eosinophilic granular cells (EGC1 and EGC2) were detected in the intestinal epithelium and lamina propria. EGC1 numbers decreased with the progression of infection, whereas an increase in EGC2 occurred, mainly in the lamina propria. The involvement of the cellular immunity in the response of D. puntazzo to E. leei was demonstrated. The depletion of this response at a certain point of the infection could contribute to the high virulence of this myxozoan in this fish species.

Usefulness of microsatellite markers developed from Pagellus bogaraveo to genetically study five different species of Sparidae

Molecular markers, such as microsatellite loci, are very important in managing and improving breeding stocks as well as in understanding the genetic structure and conservation of natural populations. In this study, we report a set of 15 microsatellite loci isolated from Pagellus bogaraveo and tested in five sparid species by cross-amplification (Sparus aurata, Dicentrarchus labrax, Diplodus puntazzo, Dentex dentex and Pagellus erythrinus). Preliminary analyses of variability were carried out on samples of every species in order to evaluate the potential use of these loci to conduct various genetic population or pedigree analyses. Amplifications succeeded for 12 out of the 15 loci in P. bogaraveo, seven for D. puntazzo, eight for S. aurata, six for D. labrax, two for D. dentex and one for S. erythrinus. No departures from Hardy–Weinberg equilibrium were found at sample level, although single departures for three loci in two species were detected. Highly promising values of variability for pedigree and relatedness analyses were detected for several loci microsatellite within the species. Allelic characteristics, showed for three microsatellite loci, allow unequivocal differentiation among P. bogaraveo, S. aurata and D. puntazzo individuals.

Effects of total replacement of fish oil by vegetable oils on n-3 and n-6 polyunsaturated fatty acid desaturation and elongation in sharpsnout seabream (Diplodus puntazzo) hepatocytes and enterocytes

The main aim of this work was to determine the impact of total dietary fish oil replacement by vegetable oils on the fatty acid metabolism of sharpsnout seabream hepatocytes and digestive tract enterocytes. Three isonitrogenous (48% crude protein) and isoenergetic (23 MJ/kg) experimental diets were formulated using three different lipid sources: fish oil (FO), rich in n-3 HUFAs; soybean oil (SO), rich in linoleic acid (LA), and linseed oil (LO), especially rich in linolenic acid (LNA). These diets were fed, three times a day to apparent satiation, to triplicate groups of 30 sharpsnout seabream (with an initial average weight of 14.9 g) for nine months at 23.5±1.2 °C. Inclusion of vegetable oils in sharpsnout seabream diet did not have any quantitative nutritional effects on desaturation/elongation of [1-14C] LNA and [1-14C] LA in isolated hepatocytes and total digestive tract enterocytes. Most of the radioactivity found in tissue lipid extracts (94% and 86% for hepatocytes and enterocytes, respectively) using silver nitrate thin-layer chromatography was recovered as [1-14C] C18 PUFA, clearly showing the lack of any significant desaturase/elongase activity in these cells. Only the high levels of HUFA in fish tissues pointed to the existence of some kind of regulatory mechanism, presumably based on HUFA bioaccumulation and C18 PUFA oxidation. Moreover, direct measurements of β-oxidation rates yielded very low values in all cases, the only significant difference being a higher oxidation rate in hepatocytes from fish fed LO versus FO diet.

Digestive enzyme activities in larvae of sharpsnout seabream ( Diplodus puntazzo)

The ontogenesis and specific activities of pancreatic and intestinal enzymes were investigated in sharpsnout sea bream, Diplodus puntazzo, during larval development until the end of weaning on day 50. The green-water technique was carried out for larval rearing in triplicate. Trypsin was first detected as early as hatching and sharply increased related to age and exogenous feeding until day 25, but a sharp decrease was observed towards the end of the experiment. Amylase was determined 2 days after hatching (DAH) and sharply increased to 10 DAH. Afterwards, slight decreases were found between 10 and 20 DAH and then slow alterations were continued until end of the experiment. Lipase was measured for the first time on day 4, and then slight increase was found to 25 DAH. After this date, slow variations were maintained until end of the experiment. Pepsin was firstly assayed 32 DAH related with stomach formation and sharply increased to 40 DAH. Then it was fluctuated until end of the experiment. Enzymes of brush border membranes, alkaline phosphatase and aminopeptidase N, showed similar pattern on specific activities during the first 10 days. Thereafter, while specific activity of alkaline phosphatase slightly decreased to 15 DAH and fluctuated until 20 DAH, aminopeptidase N activity slowly declined to 20 DAH. Afterwards, activity of alkaline phosphatase and aminopeptidase N were sharply increased to 30 DAH, showing maturation of the intestinal digestive process and also these activities continued to slight increase until end of the experiment. The specific activity of cytosolic peptidase, leucine-alanine peptidase sharply increased to on day 8, then suddenly declined to 12 DAH and further decreased until 20 DAH. After this date, in contrast to enzymes of brush border membranes, it sharply decreased to 25 DAH and continued to gradually decline until the end of the experiment. These converse expressions were indicative of a maturation of enterocytes and the transition to an adult mode of digestion.

Sharpsnout sea bream ( Diplodus puntazzo) humoral immune response against the parasite Enteromyxum leei (Myxozoa)

The humoral innate immune response of sharpsnout seabream Diplodus puntazzo against the myxozoan Enteromyxum leei was studied. Enteromyxosis was transmitted by cohabitation and a group of uninfected fish served as control. At 5, 12, 19, 26, 40 and 55 days post-exposure (p.e.), control and recipient fish were sampled to determine the prevalence of infection and some humoral innate immune parameters (antiprotease, antitumoral and peroxidase activities). Prevalence of infection was high from day 12 p.e. and reached 100% at days 40 and 55, when intensity of infection was medium to severe. The antiprotease activity was significantly increased in E. leei-exposed fish with respect to control fish at days 12 and 19 p.e. The serum antitumoral activity was slightly lower in recipient than in control fish at all sampling times, except at 40 days p.e., though no statistically significant differences were observed. Serum peroxidases were higher in all recipient fish than in control ones, with the highest stimulation index at 40 days p.e. Within recipient fish, no differences were detected between sampling times in any of the measured activities. The possible implication of these immune factors in the high susceptibility of D. puntazzo to this enteromyxosis is discussed.

Somatic indexes, chemical-nutritive characteristics and metal content in caught and reared sharpsnout seabream (iplodus puntazzo)

The aim of this study was to compare some somatic indexes, chemical-nutritive characteristics and the contents of some metals (Pb, Cu, Cr and Zn) in the whole body and fillet from caught and reared sharpsnout seabream (Diplodus puntazzo). The fish came from three different conditions: reared in marine cages (R), captured in a natural lagoon (L) and in the Mediterranean sea (S). Thirty fish per group, divided into three weight categories (100±15.3, 200±18.7 and 300±20.4g), were used for the trial.Reared sharpsnout seabream showed higher amounts of celomatic fat (3.41%, 2.43%, 0.21%, respectively for R, L and S) and total lipid (13.86%, 11.23% and 5.06% respectively for R, L and S), and lower moisture (64.14%, 65.54%, 71.53%) and protein (17.73, 19.03 and 19.17%) than those caught in the lagoon and sea. The whole body of reared fish contained lower amounts of lead (0.70, 0.75 and 0.97mg/kg, respectively for R, L and S), copper (0.15, 0.38, 0.25mg/kg) chrome (2.19, 3.52, 3.77mg/kg) and higher zinc contents (63.47, 53.42, 47.31mg/kg) than caught fish.Fatty acids from sharpsnout seabream fillets showed a high lipid quality as confirmed also by low values of Thrombogenic index (0.36, 0.30 and 0.22, respectively for L, S, R) and Atherogenic index (0.47, 0.42 and 0.33, respectively for L, S, R). Reared sharpsnout seabream showed lower saturated fatty acid values (26.44%, 32.21%, 34.85%, respectively for R, S, L) and higher oleic acid amount (21.61%, 19.15%, 11.99%, respectively for R, L and S). The subjects captured in the sea had a higher arachidonic acid content (5.44%, 1.76%, 0.59%, respectively for S, L, R).In the weight categories, the 100g subjects, showed higher incidence of viscera (VSI: 4.32%, 3.12% and 2.92%, respectively for 100, 200 and 300g) and liver (HIS: 2.20%, 1.97%, and 1.77%, respectively for 100, 200 and 300g), higher moisture (69.49%, 67.03%, 64.69%) and lower lipid rate (7.64%, 10.18%, 12.32%).

Lamellodiscus theroni sp. nov. (Monogenea, Diplectanidae), a gill parasite from Diplodus puntazzo (Teleostei, Sparidae) from the Mediterranean Sea

AbstractWe propose to name as Lamellodiscus theroni sp. nov., the gill parasite of Diplodus puntazzo (Cetti) that was reported by Euzet (1984) as L. ergensi Euzet and Oliver, 1966 in Kerkennah Island (Tunisia). L. theroni sp. nov. was also found specific to D. puntazzo in Algiers Bay (Algeria) and in Gulf of Lion (France). The host specificity of various Lamellodiscus species on D. puntazzo is briefly discussed. Within Lamellodiscus, L. theroni belongs to the “ignoratus” group characterized by a “lyre” shaped male copulatory organ and to the “ergensi” subgroup, characterized by a complex morphology of the haptoral dorsal bars. L. theroni differs from the five other species of this subgroup (L. ergensi, L. kechemirae, L. tomentosus, L. sanfilippoi, L. baeri) by the morphology and the size of the haptoral dorsal bar. L. theroni, as well as, L. hilii, L. bidens, L. impervius, was only reported on the sparid Diplodus puntazzo. These parasite species are all considered as oioxenic.

Host Switch of Lamellodiscus elegans (Monogenea: Monopisthocotylea) and Sparicotyle chrysophrii (Monogenea: Polyopisthocotylea) between Cage-reared Sparids

Sharpsnout bream (Diplodus puntazzo) has been used in Adriatic aquaculture for less than a decade, but the decreasing trend of rearing this species will probably result in its complete substitution by more exploited sea bream (Sparus aurata). Only two facilities still rear both fish species in neighbouring cages in monoculture. A switch of parasites was observed between sparids during monitoring of the gill monogeneans of farmed fish. In wild fish of the Adriatic Sea, Lamellodiscus elegans (Monogenea: Monopisthocotylea) has previously been reported in annular (Diplodus annularis), and two-banded sea bream (D. vulgaris) and sharpsnout bream (D. puntazzo), and the present study confirmed its presence also in sea bream, in low prevalence and abundance. The exclusively sea bream monogenean Sparicotyle chrysophrii (Monogenea: Polyopisthocotylea) was also isolated from sharpsnout bream, showing prevalence and abundance values even higher than in its resident host. In the occurrence of L. elegans in sea bream, the opportunistic switch resulted in lower abundance and prevalence than in the original host, while in the second case of switching the monogenean S. chrysophrii showed better reproductive capacity on a new host (sharpsnout bream). Both cases point to the possible enlargement of parasite host range.

Evaluation of bioavailability of individual amino acids in Diplodus puntazzo larvae: Towards the ideal dietary amino acid profile

The indispensable AA profile of fish carcass has been commonly used as a good indicator of fish amino acids requirements. Amino acids composition of the whole body tissue of Diplodus puntazzo was determined for the larval ages of 5, 9, 12, 17, 25 and 35 days after hatching (DAH). No significant differences were found during this species ontogeny for any indispensable amino acid although for dispensable amino acids, significant differences were found for glutamate and glutamine ( p = 0.003), aspartate and arparagine ( p = 0.027) and serine ( p = 0.027). In order to obtain the ideal dietary amino acid profile, bioavailability was determined using 15N-labelled rotifers together with GC-C-IRMS. High relative bioavailabilities were found for isoleucine, leucine and valine, meaning these amino acids are retained more efficiently. On the contrary, alanine, glutamate and aspartate presented a lower bioavailability when compared to lysine. Histidine appeared to be the first limiting amino acid at 4 days after hatching (DAH) when larvae were fed rotifers. At 12, 25 and 35 DAH the first limiting amino acid seemed to be threonine. Comparing amino acid profiles, with and without taking into account the relative bioavailability data, accentuated differences were found for methionine and leucine. Using larval amino acid profiles corrected with relative amino acid bioavailability enables an estimation of the ideal dietary amino acid profile for Diplodus puntazzo.

Fishmeal replacement by alfalfa protein concentrate in sharp snout sea bream Diplodus puntazzo

Fishmeal replacement by alfalfa protein concentrate in sharp snout sea bream Diplodus puntazzo