Sea Bream Sparus Aurata Larvae Research Articles

GROWTH PERFORMANCE AND SURVIVAL OF GILTHEAD SEABREAM SPARUS AURATA LARVAE FED ROTIFER AND ARTEMIA

The experiment was carried out in order to study the effect of a rotifer Brachionus plicatilis and encapsulated Artemia nauplii as a live food on survival rate and growth performance for gilthead sea bream Sparus aurata larvae. Gilthead sea bream larvae (20 days old) with body length and weight of (7.3 + 0.20 mm) (5.4 + 0.10 mg) respectively, were stocked in twelve white fiberglass tanks (each of 400 Liter volumes) at a density of 1200-larvae/tank. Treatments were tested as follows, 1) low rotifers and low artemia (LRLA); 2) high rotifers and low artemia (HRLA) 3) low rotifers and high artemia (LRHA); and 4) high rotifers and high artemia (HRHA) for 24 days (10, 30 rotifers and 100, 200 artemia /ml, during the periods 1st, 8th, 9th , 16th, 17th and 24th days of the feeding experiment). Feeding of higher levels of rotifers and artemia increased the survival rate of S. aurata to 48.96%, however, the lower levels of both resulted in only 12.17 % survival rate. Other intermediate treatments of HRLA or LRHA resulted in better improvements in the survival rates (19.08 and 32.21% respectively) of S. aurata larvae. Values of growth performance of S. aurata larvae (gain in length and weight; average daily (gain in length and weight; and specific growth rate) were significantly increased with increasing the levels of live food from both rotifers and artemia. The results clearly showed the superiority of the higher levels of live artemia in enhancing growth performance of S. aurata larvae than rotifers. Finally, a suitable live food program to improve the survival rates of S. aurata larvae by feeding high levels of rotifers and artemia could be recommended.

Ontogenesis of opercular deformities in gilthead sea bream Sparus aurata: a histological description.

The aim of this study was to characterize histological changes during opercular osteogenesis in farmed gilthead sea bream Sparus aurata larvae from 7 to 69 days post hatching (dph) and compare normal osteogenesis with that of deformed opercles. Mild opercular deformities were first detected in 19 dph larvae by folding of the opercle's distal edge into the gill chamber. Here, the variation in the phenotype and the irregular bone structure at the curled part of the opercles is described and compared with the histology of normal opercles. Results indicated that deformed opercles still undergo bone growth with the addition of new matrix by osteoblasts at the opercular surface, especially at its edges. No significant difference was found in bone thickness between deformed and normal opercles. In addition to differences in bone architecture, differences in collagen fibre thickness between normal and deformed opercles were also found.

Effect of a rotifer and artemia on survival and growth performance of gilthead seabream Sparus aurata larvae.

Effect of a rotifer and artemia on survival and growth performance of gilthead seabream Sparus aurata larvae.

Effect of Reducing Water Salinity on Survival, Growth Performance, Chemical Composition and Nutrients Gain of Gilthead Sea Bream Sparus aurata larvae.

Effect of Reducing Water Salinity on Survival, Growth Performance, Chemical Composition and Nutrients Gain of Gilthead Sea Bream Sparus aurata larvae.

Dietary n-3 HUFA deficiency induces a reduced visual response in gilthead seabream Sparus aurata larvae

Developmental changes in swimming speed were analysed in the seabream ( Sparus aurata) larvae. Four feeding regimes using live preys (rotifer Brachionus plicatilis) enriched with fish oil, soybean oil, linseed oil and rapeseed oil, differing in fatty acid profile, were tested during the first weeks of larval life. There was an increase in burst swimming speed and cruise swimming speed during the visual stimulus experiment at day 16th of life in the present study in agreement with the better eye development in larvae of this age. Swimming activity before stimulus was significantly reduced when larvae were fed rotifers enriched with vegetable oils. Larvae fed with rotifers enriched with fish oil reacted with a higher burst swimming speed after a visual stimulus than after the sound stimulus (159.5 SL/s vs. 18.30 SL/s) denoting the importance of the vision during this period of development not only for predation but also for the burst. The reduction in dietary essential fatty acid contents, by the enrichment with vegetable oils, delays the appearance of response to visual stimulus, in agreement with the minor DHA content in eyes and brains of these larvae and suggesting a delay in the functional development of brain and vision.

Optimization of Artemia Metanauplii on Growth and Survival of Gilthead Sea Bream Larvae Sparus aurata

Abstract–Growth, feed efficiency and survival of gilthead sea bream Sparus aurata larvae fed exclusively various levels of enriched Artemia during the period 25 DPH‐34 DPH were investigated. Larvae had an average initial fresh body weight (BW) of 4.99 mg and were fed on Artemia at rates of 20, 35, 50, 65, and 80% of their body weight per day, in two equal meals. Each ration was administered to duplicate groups of 1,000 larvae, with ration readjusted every second day. Feeding rate had a significant effect on larval survival, which was lower in larvae fed the 20 and 35% BS/d rations. The specific growth rate (SGR) showed a curvilinear significant increase when the feeding rate was increased from 20 to 65% BW/d, but there was no improvement when the feeding rate was increased from 65 to 80% BW/d. Percent feed efficiency (FE) decreased significantly from a maximum value at 20% ration to 80% BW/d but at 65% and 80% rations the values of FE were not significantly different. Optimum ration (minimum quantity of Artemia concomitant with maximum larval growth) was estimated close to 65% BW/d. The significance of the results is discussed in relation to potential economics of Artemia cysts use in commercial hatcheries.

Osteologic development of the viscerocranial skeleton in sea bream: alternative ossification strategies in teleost fish

The ontogeny of the viscerocranial skeleton of sea bream Sparus aurata larvae was studied from 1 to 90 days post‐hatching. In the smallest specimens analysed at 2·7 mm LN no cephalic elements were present and at 3·1 mm LN the following cartilaginous structures were visible: trabecula cranii, auditory capsule, Meckel's cartilage, quadrate, hyosymplectic cartilage, sclerotic, hypohyal, ceratohyal epihyal cartilage, interhyal, hypobranchial 1 and ceratobranchial 1. The only structure ossified at this size is the maxillary and the next ossified structures to appear are the preopercle and opercle at about 3·7 mm LN. The last bones to appear are infraorbital 2 and 6 at 15·1 mm LS. The first cartilaginous elements and structures to ossify in S. aurata appear to be related with functional requirements, so that structures involved directly in feeding and breathing generally appear and ossify before those that are not. The ontogeny of different regional structures revealed that generally the dermal bones ossify before the cartilage replacement bones. Comparison of S. aurata viscerocranial skeleton ontogeny with that of phylogenetically distant fish demonstrates that different ossification strategies exist in higher and lower teleost fish.

The effect of glycerol dissolved in the rearing water on the transition to exotrophy in gilthead sea bream Sparus aurata larvae

The effects of glycerol added to seawater at different concentrations were tested in monocultures of Chlorella minutissima and Brachionus plicatilis in mixed cultures of these two species and on starved or fed Sparus aurata larvae. Glycerol enhanced the growth of Chlorella and seemed to indirectly benefit the rotifers that feed on it. Its beneficial effect on gilthead sea bream prelarvae and larvae resulted in glycogen accumulation in the liver and absence of signs of cholestasis-like pathology. This effect varied according to the glycerol concentration in the water, to its addition timing and to light and feeding conditions. The gluconeogenic origin of the hepatic glycogen reserves is discussed, together with the mediating role of the food chain in glycerol larval assimilation.

Development of osteological structures in the sea bream: vertebral column and caudal fin complex

The development of cartilaginous structures in cultured sea bream Sparus aurata larvae and the timing of their ossification was studied. In cultivated sea bream larvae the first cartilaginous structure to be identified was hypural 1 at 4.1 mm notochord length (LN). By 5.3 mm LN, prior to the onset of ossification, it was possible to distinguish the following cartilaginous structures: all 23 neural arches, all 13 haemal arches and two of the four pairs of parapophyses. The neural arches 1–4 and 15–23 were formed on the notochord and elongated dorsally, while neural arches 5–14 appeared on the dorsal side of the spinal cord and elongated ventrally. Initiation of ossification occurred at 5.7–6.0 mm standard length (LS) when the cartilaginous ontogeny of the vertebral column was completed. Ossification was coincident with dorsal flexion at the posterior end of the notochord and occurred in a sequential manner: (1) dorsoanteriorly, the cartilaginous neural arches and the centra were the first structures to ossify; (2) ventrad at the centre, at 7.0–7.5 mm LS; (3) posteriorly at 7.1 mm LS the hypural complex and urostyle (24th centrum) were ossified; and (4) dorsad at the centre (neural arches and spines).

The mode of action of Artemia in enhancing utilization of microdiet by gilthead seabream Sparus aurata larvae

In recent years, a great deal of interest has been generated in the development of a microdiet (MD) as an economic live food alternative for the larvae of commercially important species of marine fish. Despite the poor performance of microdiets (MD) when used exclusively to rear marine fish larvae, results were markedly improved when inert MDs were co-fed with live Artemia nauplii. This paper reviews the influence of Artemia on the enhancement of the ingestion, digestion and assimilation of MD during co-feeding with an emphasis on work carried out at the National Center for Mariculture (NCM) in Eilat, Israel. The accumulating information and findings at the NCM suggest two possible modes of influence by Artemia nauplii on the ingestion, digestion and assimilation of MD during co-feeding: (1) the remote influence on MD ingestion by visual and chemical stimuli and/or (2) the direct influence of nauplii biochemical composition on larval digestion and assimilation. The MD ingestion rates in seabream larvae when exposed to both Artemia visual and chemical stimuli, at various concentrations of Artemia nauplii, increased up to 120% as compared to ingestion rates in larvae that were offered MD alone. The free amino acids (FAA) alanine, glycine and arginine and the compound betaine were identified as the chemical stimuli for gilthead seabream larvae from the 14 metabolites found in the Artemia rearing medium. The effect of exogenous enzymes on digestion and assimilation in gilthead seabream larvae was demonstrated when pancreatin supplementation to a MD enhanced its assimilation by 30% and significantly improved growth while seabass ( Dicentrarchus labrax) larvae were unaffected by a similar pancreatin supplementation suggesting species-specific proteolytic ability during larval development. The Artemia body composition may also contain substances exerting an influence on larval digestion and assimilation. MDs supplemented with various fractions extracted from Artemia nauplii i.e. neutral and polar lipid classes or a non-lipid fraction, separately and in combination, significantly increased MD assimilation by 10–20% in 22-d old larvae while the effect of the supplemented fractions diminished with age. In a series of follow-up studies the results indicated that Artemia phosphatidylcholine (PC), lysophosphatidylcholine (LPC) and the free fatty acid (FFA) fraction influenced significantly ( P < 0.05) MD assimilation compared to the other lipid classes. The consumption of Artemia nauplii may also increase the production of bombesin, a hormone influencing digestion. When Artemia nauplii were given as the sole food to the larvae, the presence of bombesin increased by 300% as compared to the levels that were found in larvae given only a MD.