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The effects of three temperatures (16°C, 19°C and 22°C) during the seabream larval rearing period (60 days) were studied in terms of growth (total length, T.L.), the ontogeny of the digestive system and lipid deposition in the liver (area covered with lipid vacuoles, ACLV%). The trials were performed in duplicate for each treatment. Seabream eggs were stocked (100 eggs L-1) in each 500-L tank. The larvae were reared using an intensive rearing protocol, which offers a combination of enriched rotifers (5 to 7 ind ml-1) followed by Artemia nauplii (0.5 ind ml-1) and finally with dry artificial food, the provision of which started when the total length of larvae was close to 15 mm. The ontogeny of the digestive system and the estimation of ACLV in the liver were performed using histological and image analysis methods. The results showed that the studied parameters were affected by temperature variation. The total length of larvae at the end of the rearing procedure was significantly higher at the temperature groups of 22°C (24.1 ± 3.6 mm) and 19°C (20.11 ± 1.8 mm) than the group of 16°C (12.6 ± 2.1 mm). The rate of digestive system ontogenesis was analogous to the temperature as it was completed (stomach with gastric glands appearance) at 33 dah (T.L. 9.55 ± 0.1.47 mm, 726-degree days), 35 dah (T.L. 11.00 ± 0.78 mm, 665-degree days) and 60 dah (T.L. 12.86 ± 1.68 mm, 960-degree days) in the groups 22°C, 19°C and 16°C respectively. Four distinctive phases were presented concerning the pattern of ACLV in the liver. At the first phase (from 8 to 16 dah), the ACLV was mainly higher in the 16°C and 19°C groups. During the second phase (from 19 to 35 dah), the 16°C group showed higher lipid accumulations. There was a high variation among groups in the third phase (39-45 dah). Finally, in the fourth phase (47-60 dah), the 22°C and 16°C groups showed higher liver lipid accumulation. Compared with the temperatures studied for seabream, the most appropriate rearing temperature is 19°C, constituting a cost-effective method for larval rearing. The effectiveness of the histological liver lipid analysis indicates an accurate method to evaluate feeding conditions during seabream larval rearing, indicating critical feeding periods with precision. [ABSTRACT FROM AUTHOR]

European sea bass, Dicentrarchus labrax L., groups reared under different conditions during larval stages (mesocosm and intensive rearing) were monitored during on-growing in sea cages until marketable size (350-400 g). Four caged groups were followed for a period of 17 months each at a pilot scale farm, where vertical distribution behaviour was monitored. This was performed while fish were under calm conditions, during feeding and when stress events occurred. Also during two specific periods: (i) spawning and (ii) high water temperature. Clear differences in the behavioural pattern of swimming depth, displacement and used space between the groups were observed. The individuals from the mesocosm rearing were more sensitive to human presence, showing stronger reactions (speed of displacement and vertical distribution). Most pronounced differences were observed during the 'extreme' warm period and the reproductive season. Within the seasons, European sea bass responded during feeding and stress showing a tendency to move deeper compared to calm conditions. The increased displacements were longer during feeding and stress. [ABSTRACT FROM AUTHOR]

The working hypothesis of the present study is to verify whether, the spatial distribution of sea bass fry remains invariable under the pressure of certain rearing conditions, due to its extended plasticity or, certain situations lead to specific distributions. for this reason, we investigated and com pared horizontal and vertical distribution of sea bass reared in aquaria, at three different stocking densities (5 ind. l-1, 10 ind. l-1 and 20 ind. l-1), two different temperatures (16 and 23°C) and two different feeding conditions (feeding fish and starving fish). the analysis of the video records and General Linear Models revealed a strong effect of stocking density, feeding condition, and day of experimentation on fish behavior interpreted by the vertical and horizontal distribution of fish. temperature also affected distribution when it was combined with stocking density and feeding condition. however, this effect seemed to be lessened by the effect of the other variables (i.e. stocking density, feeding condition and day of experimentation). the exposure time (chronic stress) to the stocking density, temperature and feeding condition as well as to their additive cumulative effect (variables interactions) was the cause of the development of stereotypic behaviors that increased in occurrence frequency and over an experimental time lapse and gradually led to the weakening and death of the fry (bad welfare). thus, it is assumed that stocking density, feeding condition, day of experimentation and temperature can have negative effects on sea bass "well being" and in order to maintain its welfare during rearing it is important to take all necessary pre cautions of handling when dealing with these variables in the fish environment. [ABSTRACT FROM AUTHOR]

Five cultures of microalgae ( C hlorella minutissima, T etraselmis chui, N annochloropsis sp., A rthrospira platensis and I sochrysis sp.) with no culturable bacteria were tested for their ability to inhibit the growth of six V ibrio bacterial strains ( V . parahaemolyticus, V . anguillarum, V . splendidus, V . scophthalmi, V . alginolyticus and V . lentus). The influence of light on the antibacterial activity of the microalgae was investigated. All microalgae cultures inhibited the growth of bacteria compared with the control treatments ( P < 0.05), and their antibacterial activity was not influenced by the presence or absence of light. In the control groups, the numbers of bacteria increased exponentially during the experimental period in the absence of microalgae cells demonstrating that the bacterial cells were able to utilize the growth medium of microalgae cultures. The present results may explain the low levels or absence of V ibrio strains in microalgae cultures, and the positive effect of addition of microalgae in rearing of fish larvae, and implicate the production of antibacterial compounds by microalgae cells. [ABSTRACT FROM AUTHOR]

Microbiological conditions in 200 L cultures of microalgae Chlorella minutissima in polyethylene sleeves were examined. The influence of addition of antibiotic (nitrofurantoin) was studied. Samples were taken 2, 5, 9, and 14 d after inoculation and were spread on solid Zobell medium and on thiosulfate citrate bile salts sucrose agar for the enumeration of total numbers of bacteria and numbers of presumptive Vibrio bacteria, respectively. Microalgae grew well in the cultures and high numbers of culturable bacteria (about 107 bacteria/mL) were present in all microalgae cultures. Addition of antibiotic in 200-L cultures of C. minutissima did not result in a significant decrease of total counts of bacteria per unit volume ( P > 0.05), while the numbers of presumptive Vibrio were higher in cultures added antibiotic compared with the control treatment ( P < 0.05). The numbers of presumptive Vibrio per unit volume and the percentage of fast-growing bacteria were higher in microalgae supernatant than in noncentrifuged samples. Representative colonies were taken from all samples and in total 649 bacterial strains were isolated during this study. A range of phylotypes was identified by amplification and sequencing of the 16S rDNA gene and phylogenetic trees were constructed. Several members of the Roseobacter clade were dominant among the culturable isolates. [ABSTRACT FROM AUTHOR]

The rotifer Brachionus plicatilis is a common brackish-water zooplankter, and one of the beststudied rotifer species. It is characterized by high growth rate, widespread distribution, ubiquity in aquatic systems, ease of culture, adequate size, ability to feed on a variety of feed types and a complex life cycle. It has been used extensively as a tool in aquaculture and ecotoxicology and constitutes a model organism in ecological and evolutionary studies. This paper explores other possible uses of this organism in various fields: environmental control of eutrophication and harmful algal blooms, containment of cholera, management of pollution and petroleum compounds, wastewater treatment, impact of climate change on biodiversity and transfer of useful substances. [ABSTRACT FROM AUTHOR]

This study describes the rotifer mass culture protocol developed at the Institute of Aquaculture (HCMR) in Crete. Rotifers were cultured semi-continuously at a density of 257.6 ± 2.6 ind. mL−1, with a daily dilution rate of 25%. An automatic feeder was used to administer dry feed (Selco Sparkle®) every 10 min. A number of factors were investigated so as to provide an in-depth analysis of the advantages and disadvantages of the two systems, especially when compared with traditional protocols such as batch culture. The use of these two systems resulted in a culture of considerable duration (41 days) and daily yield (0.21 ± 0.01 ind. 106 day−1 L−1), using exclusively dry feed. Both systems can be easily applied in hatcheries, requiring few modifications on existing protocols and contribute to a stable and predictable production. Further improvements include manipulation of the dilution rate, food ration, culture volume and duration, as well as choice of a phytoplankton-based diet. [ABSTRACT FROM AUTHOR]

In the present study the reproductive biology of Tonna galea (Linnaeus, 1758) was studied for the first time. In mid-September 2006 one individual was found laying a pale pink egg rosette of 39.5 cm length. Number of embryos, stages of development, shape and dimensions were studied in relation to time and measured on microphotographs of randomly sampled capsules. Each oval or spherical shaped capsule of 3.61 mm total length contained 101 developing embryos. The embryo diameter ranged from 297.5 µm of the unsegmented egg to 489 µm of the free veliger. At 21°C eclosion occurred 34 days after capsule deposition, at a free-swimming veliger stage. The duration of each developmental stage, from one cell to veliger, is reported. Results are discussed in relation to possible culture and use for ecological purposes. [ABSTRACT FROM AUTHOR]

Red porgies ( Pagrus pagrus) of 20.6±1.5 g mean weight were reared in tanks under four delayed self-feeding conditions (0=control, 7, 30 and 90 s) after rod activation. The time intervals were chosen to simulate the time taken for a commercial pelleted feed to transit the tube linking a surface-mounted feed hopper and the depth at which a cage might be submerged. Daily feeding rate, growth, food conversion index and condition factor were quite similar but fish behaviour differed among conditions. Fish remained close to the feeding point in the first two treatments (0 and 7 s delay) but foraged more widely in the remaining treatments (30 and 90 s delay), only reconsolidating around the feeding point a few seconds before feed was released. Results are discussed in relation to learning capacity and adaptation of fish to feeding behaviour flexibility, in order to develop reliable self-feeding systems suitable for submerged cages. [ABSTRACT FROM AUTHOR]

The freshness of red porgy slaughtered in ice slurry and stored in melting ice was evaluated instrumentally, biochemically and sensorialy. Additionally, postmortem skin colour changes were monitored, in an attempt to demonstrate the use of chromaticity parameters as a reliable and convenient approach to quality assessment. Dielectric properties showed a statistically significant decrease ( P<0.05) from 12±0 on day 0 to 7.85±0.31 on day 7; there was also a significant decrease in muscle polyamines with more than two amino groups (spermidine and spermine) and an increase in the di-amine putrescine. The sensorial score was significantly decreased from 30±0 to 4.33±0.21 on day 7. Minimal lightness ( L) and hue ( H° ab) at the dorsal skin area were observed on days 1 and 3 following harvesting. Finally, there was a marked decrease in the entire colour index (ECI - a combination of skin hue and chroma) of both the dorsal and the ventral area in day 3 onwards to day 7, as well as a statistically significant correlation between all the estimated freshness indices and ECI. Based on all these, we inferred that the total polyamines (or putrescine to spermidine and spermine ratio) and ECI could be reliable estimators of freshness, at least under the experimental conditions applied. [ABSTRACT FROM AUTHOR]

The influence of dietary mannan oligosaccharide (MOS) on the development, gut integrity and quality (in respect of stamina and survivability) of white sea bream Diplodus sargus L. larvae was investigated. White sea bream larvae were held under appropriate rearing conditions and fed Artemia, enriched by A1 DHA Selco™ with the addition or absence of MOS (Bio-Mos®). The results indicated that larval growth performance and survivability were not affected by the MOS supplementation. Light microscopy revealed that MOS supplementation significantly improved the intestinal morphology by increasing the villi surface area by over 12%. Transmission electron microscopy revealed that MOS supplementation increased the microvilli length by 26% compared with the control. Salinity challenge experiments showed that MOS significantly increased larval stamina and survival in both 0 and 60 mg L−1 salinity water by 13% and 22.9% respectively. These improvements in the larval quality at the early stages of fish development are important for the efficiency of intensive hatchery production. [ABSTRACT FROM AUTHOR]

Unicellular green alga Chlorella minutissima, grown under extreme carbon dioxide concentrations (0.036–100%), natural temperature and light intensities (Mediterranean conditions), strongly increase the microalgal biomass through photochemical and non-photochemical changes in the photosynthetic apparatus. Especially, CO2 concentrations up to 10% enhance the density of active reaction centers (RC/CSo), decrease the antenna size per active reaction center (ABS/RC), decrease the dissipation energy (DIo/RC) and enhance the quantum yield of primary photochemistry (Fv/Fm). Higher CO2 concentrations (20–25%) combine the above-mentioned photochemical changes with enhanced non-photochemical quenching of surplus energy, which leads to an enhanced steady-state fraction of ‘open’ (oxidized) PSII reaction centers (qp), and minimize the excitation pressure of PSII (1 − qp) under very high light intensities (approximately 1700 μmol m−2 s−1 maximal value), avoiding the photoinhibition and leading to an enormous biomass production (approximately 2500%). In conclusion, these extreme CO2 concentrations – about 1000 times higher than the ambient one – can be easily metabolized from the unicellular green alga to biomass and can be used, on a local scale at least, for the future development of microalgal photobioreactors for the mitigation of the factory-produced carbon dioxide. [ABSTRACT FROM AUTHOR]

Shape ontogeny of Diplodus puntazzo was studied during the larval and metamorphosis phase (2.6–33.0 mm total length (TL)) by means of geometric morphometrics. Additionally, shape comparison was performed between newly settled wild individuals of D. puntazzo (11.0–18.0 mm TL) and reared of the same TL range. Results clearly demonstrated that shape ontogeny of D. puntazzo is not continuous during the studied period, but it is characterized by the presence of two inflection points (at 6.2 and 11.4 mm TL), which define three phases of significantly different rates of shape development ( P<0.05). Spline diagrams demonstrated that shape ontogeny mainly correlated with the development of fins, caudal peduncle, snoot and the ventral abdominal profile. Concerning the comparison of reared fish with wild fish, morphometric analysis revealed a significant effect of fish origin on the shape of D. puntazzo (Wilks' λ=0.147, P<0.001). Shape differences between the two populations were mainly demonstrated at the caudal peduncle and at the ventral profile of the abdominal area. Combined with the results of shape ontogeny, spline diagrams showed that shape differences between the two populations were related to the comparatively more advanced ontogenetic state of reared fish, at the studied size range. [ABSTRACT FROM AUTHOR]

The article presents a study that aims to determine whether the hybrids produced by the protandous gilthead seabream (Sparus aurata) and the protogynoyus Mediterranean red porgy (Pagrus pagrus) display sterile gonadal development. Sparids are characterized by peculiar bisexual gonads consisting of a medio-dorsal ovarian area and a latero-ventral testicular area. The female sex dominated in the hybrids with differentiated gonads. Female dominance is a common characteristic to both parental species when they are 2-3 years old. Female hybrids mature with delay compared with parental species regardless of their normal gonadal development.

This study presents data on the effect of carotenoid sources on skin coloration of red porgy (Pagrus pagrus). Three experiments were conducted: in the first, fish were fed an astaxanthin (Naturose®)-supplemented diet, while the second fish received diets supplemented with β-carotene (Rovimix β-caroten®) or lycopene (Lyc-O-Mato®): Carotenoids were added to the level of 100 ppm in each diet, while a non-carotenoid-supplemented diet served as a control. In the third experiment, the effect of dietary protein/carbohydrate ratio on melanin content in the skin was investigated. For this experimentation, four diets were formulated to contain 50/23, 40/32, 30/48 and 20/59 protein/carbohydrate ratio. Naturose® astaxanthin increased total carotenoid content in the dorsal skin area while β-carotene and lycopene seem to have had no significant effect. Naturose® was the only carotenoid source that had a significant effect on skin hue, promoting a reddish coloration to the dorsal skin area and a ventral hue similar to wild red porgy. No apparent effect of carotenoid source on skin melanin content was observed. In contrast, dietary protein/carbohydrate ratio affected melanin content in the skin. The fish fed the 50/23 diet showed significantly higher values. Farmed red porgy had eight times higher dorsal-skin melanin content than wild ones. [ABSTRACT FROM AUTHOR]

The ontogeny of shi drum Umbrina cirrosa (Linnaeus 1758), a candidate new species for aquaculture, was studied throughout the entire larval phase. Geometric morphometric analysis revealed two clear inflection points (7.0 and 12.7 mm total length, TL) in the shape ontogeny of this species, separating the studied period into three phases of different allometric priorities. Spline graphs demonstrated that the major non-uniform shape ontogeny correlated with the development of the fins, the anterior dorsal area of the body, the caudal peduncle, the eye and the mouth. Concerning the morphological features, shi drum larvae are characterized by an upward anterior bending of the notochord. The ontogeny of the fins began with the formation of the pectoral buds (2.9 mm TL), continued with the notochord flexion (4.3 mm TL, associated with the caudal fin development), the appearance of the pelvic buds, the first anal rays (4.5 mm TL) and the first dorsal rays (4.8 mm TL). Shi drum juveniles presented 25 vertebrae and the following dominant fin types: D XI,23, AII,6, VI,5, P17 and C17. [ABSTRACT FROM AUTHOR]

Two series of experiments were conducted for the evaluation of the effect of dietary taurine supplementation on survival, growth performance and feed preference of sea bass Dicentrarchus labrax fry when fed with demand-feeders a fish/soybean meal-based diet. In the first experiment, fish were imposed one of four diets supplemented with taurine (0, 0.1, 0.2 or 0.3% taurine on a dry weight basis), while in the second they had simultaneous free access to the four diets supplemented with taurine. When not allowed to choose, fish exhibited better specific growth rate of 3.2 and 3.2% per day with diets supplemented with 0.2 and 0.3% taurine than those of 2.3 and 2.2% per day of 0 and 0.1% taurine, respectively. When fish were free to access the diets, they selected more actively the 0.2 and 0.3% taurine-supplemented diets than the 0 and 0.1% taurine. As survival was not significantly different among trials, the results indicate that sea bass fry require a 0.2% taurine in the diet for better growth when fish meal and soybean meal are the primary sources of protein. The positive correlation between growth performance and nutrient preference is discussed as a method for improvement of fry food formulation. [ABSTRACT FROM AUTHOR]

Cultured red porgy Pagrus pagrus (L.) males ( n=6) were sampled every 2 weeks for milt, in order to monitor changes in sperm quality parameters during a whole spawning period. On 11 January 2001, 60% of the fish were spermiating, increasing to 100% in mid-February and dropping to 30% by mid-April. Sperm density showed a slight increasing trend, with mean values ranging between 8.6 and 23.7×109 spermatozoa mL−1. Sperm motility percentage exhibited a significant improvement during the spawning season (analysis of variance ( anova) P=0.0001). The duration of forward motility for the major part of the monitoring period ranged between 2 and 4 min. Red porgy spermatozoa maintained their viability for many days after whole storage of milt at 4°C. During the monitoring period there were significant changes in the mean duration of sperm survival after cold storage, ranging from 5 to 12 days. The total volume of expressible milt was maximal on 28 March, increasing from a mean value of 1.7 mL to 5.3 mL kg−1. Milt production of captive-reared red porgy does not appear to be limiting, when compared with the volume of expressible milt produced by other cultured marine fishes. [ABSTRACT FROM AUTHOR]