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Made available in DSpace on 2022-04-29T08:41:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 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. Centro de Aquicultura da Universidade Estadual Paulista “Júlio de Mesquita Filho” (CAUNESP) Institute of Marine Biology Biotechnology and Aquaculture Hellenic Center for Marine Research Beacon Development King Abdullah University of Science and Technology Centro de Aquicultura da Universidade Estadual Paulista “Júlio de Mesquita Filho” (CAUNESP)

The Mediterranean Triton Charonia seguenzae (Aradas & Benoit, 1870) is an endangered marine gastropod. Re-establishment of C. seguenzae populations in the depleted habitats requires knowledge of its biology and breeding in captivity. Temperature has been recorded to affect the development in marine gastropods. The present study aims to describe the encapsulated development and study the effect of three temperature regimes, that the embryos are exposed to in the wild (17, 20, 23οC), on it. At the stage of morula (7th Day After Deposition – DAD) 180 egg capsules were separated in three groups of 60 capsules. One group remained at 23 °C and the other two were acclimated at 20 and 17 °C. Two capsules were sampled randomly from each temperature setup (every day during the first 5 days, D1-D5, every other day from D7 to D17 and every other two days from D20 to eclosion), opened and the eggs, embryos or larvae were photographed under stereoscope. Stages of development and shape were assessed and dimensions were measured from microphotographs. All developmental stages were described in relation to temperature and time. At 23οC eclosion of free swimming veligers occurred 49 DAD, 17 days faster than the embryonic development at 20οC. Eclosion at 17 οC was not observed up until the 74th DAD when the last sampling was conducted. An increased amount of larval deformities was observed at 17οC reaching 94% during the last sampling (D74), while at eclosion only 4 and 3% of the hatching larvae were deformed at 20 and 23 οC respectively. In this study temperature appears as a key factor during the development of the marine gastropod Charonia seguenzae, affecting the survival and developmental rate. Although temperature affected the size of intermediate stages, the size of free swimming veligers at 20 and 23 οC did not differ.

The histological development of the visual system of meagre (Argyrosomus regius) was studied from hatching to juvenile stage (44 days post hatching, dph), under aquaculture rearing conditions. The cones, horizontal, bipolar, amacrine and ganglia cells appeared already at 3 dph at a total body length (TL) of 3.11 ± 0.21 mm, at the stage of mouth opening. Rods appeared at 6 dph (TL 4.16 ± 0.73 mm) and increased their density continually during the monitoring period. On the contrary at the same period, the evolution of the number of cones, horizontal, bipolar, amacrine and ganglia cells in the retina were reduced. While photopic sensitivity increased over time, meagre may be considered as a species with well-developed scotopic sensitivity as well, already by 17 dph (TL 8.14 ± 1.64 mm). This observation suggests that instead of the commonly used 24-h continuous high light intensities used in larval rearing protocols of meagre, lower light intensities should be employed, especially during the night hours. Histological visual acuity increased with larval development and appeared to stabilize by the early juvenile stage. Based on the estimated histological visual acuity and the theoretical distance at which rotifers and Artemia may be identified by meagre larvae, minimum prey densities should be 0.5 rotifers and 0.009 Artemia ml− 1 during their first use as feed items. The study demonstrated that the majority of ontogenetic events that are related with retinal differentiation and the function of the eye occurred very early during larval development in meagre. The results provide important information for the biology of the species, as well as for the optimization of larval rearing conditions regarding light management and prey item density under aquaculture conditions.

The reproductive behavior of the gastropod Charonia seguenzae (Aradas & Benoit, 1870) was studied through the description of 19 copulation and 21 egg laying events of 134 wild individuals. Findings in the present study regarding a part of the reproduction temperature range (20 to 23oC) and the demonstration of maternal care provided important information on their biology, behavior and ecology. Furthermore, observed polyandry by the females and collaborative care of embryonic sacks, were two aspects of the species reproductive biology that pose new questions both at ecological and evolutionary level.

Finfish present a great ability to modify their phenotype in response to environmental conditions especially in the early ontogenetic period. Such plastic phenotypic responses have a great importance, from both the ecological and aquaculture point of view. The present study examined the effect of water temperature on the ontogeny and juvenile phenotype of Sparus aurata L. Six combinations of three temperatures (16, 19, and 22 °C) were applied during different phases of ontogeny up to the juvenile stage (ca 33–37 mm standard length, SL). Elevated temperature resulted in a relative acceleration of differentiation versus growth, which morphologically was evident as a significantly smaller SL (ca 11% decrease) at different ontogenetic events (development of fins, squamation and body shape). Moreover, geometric morphometric analysis clearly showed a significant effect of water temperature during early ontogeny on the juvenile body-shape. Thermally-induced variation of juvenile body shape was mainly expressed across the first canonical axis (56.4% explained variance), which discriminated the groups of highest temperatures from the rest. Water temperature mainly affected the position of the bases of supraoccipital and of basioccipital bones, of the upper jaw, as well as of the dorsal, anal and pelvic fins. The results are discussed with respect to the potential use of thermal manipulations during the hatchery phase to control the phenotype of S. aurata at the end of on-growing phase, i.e. at commercial size.

Consumption and digestibility rates of four food items (sea star: Luidia sarcii and Astropecten aranciacus, squid: Nototodarus sloanii, shrimp: Parapenaeus longirostris and fish: Boops boops) by the marine gastropod Charonia seguenzae were studied. The food with the greatest mean daily consumption in wet weight was the sea star with 24.03 ± 2.69 g, followed by fish (11.36 ± 3.74 g), shrimp (9.52 ± 1.21 g) and squid (7.36 ± 2.16 g). Absorption rate was higher when squid was consumed (97.1 ± 3.7%, dry weight) followed by shrimp (93.5 ± 4%), fish (87.8 ± 8.6%) and sea star (45 ± 15.3%). Although squid absorption was higher, due to high consumption rates against sea star and fish, energy input did not differ significantly. Tritons absorbed a large proportion of ash only when consuming sea star. Results indicate that C. seguenzae can adapt well in captivity conditions by efficiently digesting alternative foods. Furthermore, a low metabolism is indicated by its low transit that needs 6 to 8 days to digest food consumed from a single feeding.

Histological development of the digestive system was studied in association with feeding preferences in meagre ( Argyrosomus regius ) from hatching to juvenile (44 days after hatching, dah), using a mesocosm system. In addition, the liver lipid content was evaluated using histological methods (area covered with lipid vacuoles, ACLV%). The ontogeny of the digestive system was completed by 19 dah (or 444 degree days) with the gastric glands appearing at 15 dah (361 degree days), the pyloric ceaca at 17 dah (404 degree days) and the Y-shaped stomach formed at 19 dah (444 degree days). The rearing period was characterized first by relatively slow growth until tail flexion (~ 15 dah) and fast growth thereafter (mean ± SD total length of 45.14 ± 4.00 mm at 44 dah). When the feeding protocol included exclusively rotifers, mean ACLV remained low (2.39 ± 0.34%) while feeding on Artemia nauplii and copepods increased liver ACLV to 47.18 ± 6.56% at 20 dah. Changes in the feeding protocol were reflected in feeding preferences (stomach content), and variations of liver lipid content and the occurrence of vacuoles in the intestine. During transition from live prey to artificial feed (~ 28 dah), ACLV decreased significantly – indicating a malnutrition period – concomitant with a delay in the acceptance of artificial feed of 8 days. Thereafter, consumption of artificial feed resulted in an increased ACLV to 56.3 ± 7.6% at 36 dah. The results indicate that during early development meagre is a fast growing species, developing rapidly the structures and basic organs of the digestive system required to overcome successfully the critical stages of larval rearing. The study also shows that histological evaluation of liver lipid content using the ACLV may be a valuable tool in commercial aquaculture to improve larval rearing protocols, and production efficiency.

Cadmium (Cd) has proved to be associated with numerous toxic effects in aquatic organisms via waterbome exposure. With a view to investigate Cd toxicity along a broad spectrum of exposures reaching from environmental to toxic, we employed adult zebrafish (Danio rerio) for an in vivo study. A number of 10 fish per tank were placed in 40 L tanks and were exposed for 30 days to 0.0, 5.0, 25, 50, 75, 100 and 1000 mu g Cd per liter. There were 2 tanks for each Cd exposure (duplicate experiment). Mortality was recorded daily, dead fish were collected and tissue samples were obtained for histologic observation, whereas remaining tissues were stored for Cd burden determination. Surviving fish were collected at the end of the experiment. Median overall survival (OS) in days was found to be 9.0, 11.0, 8.0 and 7.0 for 25 mu g/L, 50 mu g/L, 75 mu g/L and 100 mu g/L respectively, with all of them showing mortality greater than 50%. Remarkably, fish exposed to the highest Cd concentration (1000 mu g/L) survived the longest exhibiting a mean OS of 29.2 days. Cd determination in fish tissue was conducted with an in house ICP-MS method and levels ranged from 3.1 to 29.1 ng/mg. Log Cd tissue levels were significantly correlated with the log Cd exposure levels (r = 0.535, p lt 0.001). The highest Cd burden was determined for fish exposed to 1000 mu g Cd /L (mean = 12.2 ng/mg). Histopathology supported these results. Our findings disclose a deviation in toxic responses through the range of Cd concentrations, leading to nonlinear responses. These differentiated responses, could be linked to hormesis phenomena.

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.

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.

Five cultures of microalgae (Chlorella minutissima, Tetraselmis chui, Nannochloropsis sp., Arthrospira platensis and Isochrysis sp.) with no culturable bacteria were tested for their ability to inhibit the growth of six Vibrio 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

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.

The lethal effect of enteromyxosis is recorded for the first time in the humphead wrasse, Cheilinus undulatus , a tropical pet fish. Enteromyxosis was caused by the myxosporean parasite Enteromyxum leei , and the gut was the only tissue affected in this case. Severe enteritis and degeneration of the intestinal mucosa may have caused a digestive function disorder, thereby resulting in the fish's death. The histopathological findings of this case included destruction of normal tissue architecture of the intestinal mucosa, chronic inflammation, and infiltration of mast cells/eosinophilic granular cells, which resembled findings described in other fish that were diagnosed with enteromyxosis. Induced stress by transportation and entrance to a new environment possibly played an underlying role in the virulence of the parasitic infection and associated tissue pathology.

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.

The present study investigates the effects of dietary carotenoid sources on the coloration of the red porgy, Pagrus pagrus. Red porgies (131.9 ± 16.2 g; mean ± SD) were fed for 12 weeks on five different diets supplemented with red carotenoids (mainly astaxanthin esters) supplied from Haematococcus pluvialis algae and yellow carotenoids (mainly β-carotene, lutein, and zeaxanthin) supplied from Alfalfa, Medicago sativa L. and Spirulina, Spirulina pacifica. The carotenoid-supplemented diets did not have any marked effect on the growth rate, the feed conversion ratio, the daily feeding rate, or the hepatosomatic index of red porgy. The biochemical indices measured in plasma including cholesterol, total proteins, glucose, lactate, phospholipids, non-esterified fatty acids, triglycerides, and thyroid hormones did not differ significantly among groups. Diet did not affect significantly the melanophore-area coverage, the melanin skin concentration and skin lightness. Carotenoid-supplemented diets affected significantly the carotenoid deposition in the skin, the presence and distribution of erythorphores and xanthophores, and skin hue and chroma. Overall, data have shown the efficacy of Haematococcus algae in promoting a reddish coloration in red porgy.

Red porgies (Pagrus pagrus )o f 20.6� 1.5 g mean weight were reared in tanks under four delayed selffeeding conditions (0 5 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 ¢sh behaviour diiered among conditions. Fish remained close to the feeding point in the ¢rst 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 ¢sh to feeding behaviour £exibility, in order to develop reliable self-feeding systems suitable for submerged cages.

The development of skeletal deformities is an important problem for finfish hatcheries. In the present paper, the effect of water temperature on the development of skeletal deformities in Sparus aurata was examined. Six combinations of three temperatures (16, 19, and 22 °C) were applied during three ontogenetic windows: the autotrophic (embryonic and yolk-sac larval stages), the exotrophic larval (first feeding to metamorphosing larvae of 14–16 mm TL) and the juvenile (metamorphosing larvae of 14–16 mm TL to juveniles of 40–45 mm TL) periods. The results demonstrated a significant effect (p

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

Osteological development of Seriola dumerili is described and illustrated based on 141 specimens (3.9–27.0 mm TL) reared under semi-intensive culture conditions (Greece). The ontogeny of the vertebral column started with the formation of the neural arches (4.6 mm TL) and continued with the haemal arches and the centrum (4.8 mm TL). Until the end of the study, the centrum (12.5 mm TL) and neural arches (23.8 mm TL) were fully formed, while the haemal arches were not. The first skeletal elements of the fins started developing in the pectoral (3.9 mm TL), anal (4.8 mm TL), caudal (4.8 mm TL), dorsal (6.0 mm TL) and pelvic fins (6.3 mm TL), while the fin rays followed a slightly different pattern pectoral (5.6 mm TL), caudal (5.3 mm TL), anal (6.2 mm TL), dorsal (6.3 mm TL) and pelvic fin rays (7.0 mm TL). The ontogeny of the skeletal parts are compared with those of other Carangidae and Teleosts.

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.

Twelve salts were tested for their ability to coagulate microalgae cells in cultures of Chlorella minutissima. The final aim was to develop an easy and efficient approach for harvesting microalgae biomass in dense cultures. Aluminum, ferric, and zinc salts coagulated C. minutissima cultures, while optimum concentration was 0.75 and 0.5 g L−1 for sulfate and chloride salts, respectively. Aluminum salts were most efficient, but caused some cell lysis, which may render this approach inappropriate in some cases. Ferric and zinc salts were ranked second and third, respectively, according to their culture cell-coagulation efficiency. Ferric salts caused a change in the color of the cells, mainly at concentrations higher than 1 g L−1. Zinc salts were less harmful for the microalgal cells, but an additional problem was observed with cell aggregates adhering to the walls of the glass test tubes. Selection of the appropriate coagulant is related to the purpose of the coagulation process.

En Europe, la pisciculture marine s’est developpee en deux vagues successives : celle du saumon atlantique, puis celle du bar et de la daurade. L’elevage de « nouvelles especes de poissons marins » repond a de nombreux avantages complementaires. Cet article presente l’etat de la production de ces « nouvelles especes », l’historique des recherches menees, les problemes et perspectives lies au developpement de leur elevage.

article i nfo The influence of the absence of Artemia nauplii from larval diet protocols on growth and digestive system ontogeny was studied using histological techniques in the shi drum (Umbrina cirrosa). One group of larvae was reared using the standard intensive rearing protocol, which offers a combination of enriched rotifers (Brachionus plicatilis), Artemia spp. nauplii and artificial diet (Std-group). Another group was reared using the same protocol, but without the offering of Artemia nauplii (group No-Artemia). The ontogenesis of the digestive system from hatching to metamorphosis was a very rapid process, and there were no differences between the two feeding regimes in the temporal appearance of the various components of the digestive system. The first organised presence of the hepatic and pancreatic tissue appeared at 2-3 d after hatching (dah), suggesting that these organs function from a very early developmental stage. In the No-Artemia larvae between 13 and 29 dah there was a reduction in the height of enterocytes in the intestinal mucosa, a progressive flattening of the primary intestinal folds in the anterior and posterior intestine and a decrease in lipid stores in the liver, suggesting a period of relative starvation. However, by the end of the study at 41 dah, there were no significant differences in body length, intestinal morphology or liver lipid stores between larvae reared under the two feeding regimes. The study suggests that the diet may influence the maturation and/or function, but not the ontogeny of the digestive system. Furthermore, the rapid differentiation of the digestive system in shi drum and the prompt recovery of the No-Artemia larvae from the symptoms of starvation by 29 dah, indicate a plasticity during ontogenesis and the ability of larvae to adapt to artificial diets at very early developmental stages.

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.

This study aims at examining the effect of caffeine administration on growth, feed efficiency, and consumption of sea bream (Sparus aurata), reared in winter temperatures. Moreover, it is questioned whether caffeine has a central action in the brain and its effects are partly mediated via central brain mechanisms. For this, we studied the influences of caffeine treatment on the cerebral pattern of the cholinergic neurotransmission and the novel neuromodulator nitric oxide (NO), by means of acetyl-cholinesterase (AchE) and nitric oxide synthase (NOS) histochemistry. Five different diets containing 0.0, 0.1, 1.0, 2.0 and 5.0 g caffeine kg⁻¹ of diet were administrated to five groups of fish. Caffeine adversely affected sea-bream growth at a concentration higher than 1 g kg⁻¹ diet and increased feed conversion ratio in the treatments of 2 and 5 g kg⁻¹ (P < 0.05). The daily consumption of feeds was similar to all groups, indicating that caffeine did not influence diet palatability. AChE- and NADPH-diaphorase histochemistry showed densely labeled cells and fibers mainly in dorsal telencephalon, preoptic, pretectal, hypothalamic areas, optic tectum, reticular formation, cerebellum and motor nuclei. When compared with matched caffeine-treated animals, no differences in the histochemical pattern and cell densities of cerebral AChE and NADPH-diaphorase were found.

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, CO(2) concentrations up to 10% enhance the density of active reaction centers (RC/CS(o)), decrease the antenna size per active reaction center (ABS/RC), decrease the dissipation energy (DI(o)/RC) and enhance the quantum yield of primary photochemistry (F(v)/F(m)). Higher CO(2) 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 (q(p)), and minimize the excitation pressure of PSII (1 - q(p)) under very high light intensities (approximately 1700 micromol m(-2) s(-1) maximal value), avoiding the photoinhibition and leading to an enormous biomass production (approximately 2500%). In conclusion, these extreme CO(2) 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.

Common dentex were fed three isoprotein and isoenergetic diets to investigate the effect of partial substitution of fish meal by soy protein concentrate (0 [FM], 25 [SM25] and 40% [SM40]) in the presence or absence of taurine (T) supplementation (2 g kg − 1 on a dry weight basis) [FM + T], [SM25 + T] and [SM40 + T], on growth related parameters, muscle composition and bile salt activated lipase activity. The fish were fed twice a day by hand to apparent satiation over the course of a 12-week growth trial. The [SM40] diet resulted in lower feed intake compared to the [FM] and [SM25] diets, lower specific growth rate compared to the [FM] diet, lower condition factor and increased mortality of dentex compared to the [FM] and [SM25] diets. On the other hand, the [SM25] diet had no adverse effect on either feed intake or specific growth rate of dentex compared to the [FM] diet. The hepatosomatic and mesenteric fat indices did not change by increasing soy content. Moreover, no difference was observed in the composition of muscle in dentex fed different proportions of soy protein concentrate. However, the activity of the bile salt-activated lipase in liver was significantly lower in fish fed the [SM25] diet than in fish fed the [FM] diet. Dietary taurine supplementation increased the specific growth rate and daily feed intake while it reduced feed conversion ratio of dentex. Comparison among groups showed that dietary taurine supplementation increased feed intake but not specific growth rate in the [SM40 + T] group compared to [SM40] group. The condition factor was higher in fish fed the [FM] diet compared to the [SM25 + T] and [SM40 + T] diets. However, no difference was observed between the [SM25] and [SM40] groups compared with the [SM25 + T] and [SM40 + T] groups, respectively. Analysis of the chemical composition of the muscle showed that the [SM25 + T] fed fish had higher crude protein compared to the [SM40 + T] fed fish. Furthermore, the mesenteric lipid index was higher in [SM25 + T] fed fish compared to those fed the [SM25] and [SM40 + T] diets. The activity of the bile salt-activated lipase in the liver increased in fish fed the three diets [FM], [SM25] and [SM40] in the presence of taurine, indicating that taurine in diets at 2 g kg − 1 may improve lipid metabolism, although no significant differences were observed in the total fat content of the muscle of fish fed either of these experimental diets. In conclusion, it appears that in dentex, partial substitution of fish meal is possible with 25% of soy protein concentrate without affecting growth, which can be improved further by dietary taurine supplementation of 2 g kg − 1 diet.

The weaning of greater amberjack (Seriola dumerilii Risso 1810) to a dry diet was studied in two consecutive experiments. The experimental fish were hatchery-produced and grown to their initial size on a soft pellet containing 50% trash fish and 50% commercial dry pellet. In the first experiment, three homogenous groups of greater amberjacks (n = 153, mean weight: 374 ± 43 g), initially adapted for a period of 30 days to a diet with a 40% moisture content, were fed on commercial pellets containing three different levels of dietary moisture (7, 20 and 40%, respectively) for 126 days. We found that fish needed a month to adapt to the 7%- and 20%-moisture diets and that moisture content of the diet had a significant effect on fish growth in terms of increasing feed consumption and lowering feed conversion ratio. The group fed on the 20%-moisture diet not only compensated for the initial adaptation period but presented the higher growth rate and best feed conversion ratio. In the second experiment, all groups of experiment 1 were fed the same commercial diet with a 7% moisture content for 72 days. The group that had been previously fed on the 20%-moisture diet showed the best growth performance. The implication of the above results for the weaning of greater amberjack to dry diets is discussed in terms of the digestion process and physiology.

Summary The present study investigates the effect of water temperature on the development of deformities during embryonic and larval stages of European sea bass, Dicentrarchus labrax (L.). Two temperature conditions were examined in duplicate by studying the presence of skeletal deformities in a sample of 45 to 51 fish taken from each population at the end of the rearing trials [20–23 mm total length (TL)]. The results indicated that water temperature during the embryonic and larval phase has significant effects on deformation of the branchiostegal rays (P 0.05). At 15°C, 27.2–33.4% of the examined fish had branchiostegal rays of abnormal shape and/or orientation, whereas at 20°C this deformity had a frequency of only 4.0–4.1%. The frequency distribution graph of branchiostegal counts demonstrated a significant deviation in the deformed fish from the normal (seven rays on each side of the body) phenotype at both temperatures tested. This deviation was mainly expressed as a lack of one to four rays (56.7% of deformed fish), or the formation of one extra ray (26.7% of deformed fish) (P

Summary The haematological profile and a description of the cell types from the peripheral blood of six Mediterranean fish species are presented. The highest haematocrit value was recorded in the saupe, Sarpa salpa (P

Skin coloration patterns in fish are of great physiological, behavioural and ecological importance, can be considered as an index of animal welfare in aquaculture and as an important quality factor for the retail value, especially of red skinned fish. In the present study we developed an appropriate method for comparisons of the skin chromaticity parameters in wild (Pagrus pagrus, Pagrus caeruleostictus, and Dentex gibbosus) and farmed red skin Sparidae and investigated the effect of storage time on skin colour of farmed Pagrus pagrus. The three-dimensional characteristics of colour appearance (lightness — L⁎, hue — H°ab and chroma —Cab⁎) were calculated. A new index, named Entire Colour Index (ECI), was developed to express hue and chroma which as combined variables, cannot be considered separately. In all species there was a remarkable dorsoventral gradient in mean L⁎ and H°ab, with the ventral area being statistically significant brighter than the dorsal one. ECI value was species specific but did not show any statistically significant dorsoventral gradient, with the exception of P. pagrus. Skin melanin and carotenoids content presented differences between the Pagrus and the Dentex species that may explain the differences in the observed chromaticity pattern. Storage time affected lightness and hue only in the dorsal skin area. However, the effect of storage on ice was better reflected in mean ECI value which showed a marked decrease from Day 3 to Day 7 in both the dorsal (Day 0: 8.96 ± 0.40; Day 7: 2.86 ± 0.29) and ventral (Day 0: 8.97 ± 0.18; Day 7: 4.10 ± 0.29) skin area. Our results provide data for a non-subjective determination of skin colour pattern and show that ECI offers a good index of the actual colour in a meaningful and objective way.

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

We tested the effect of water-temperature during the larval phase on sea bass sensitivity to current-induced lordosis. During larval rearing phase, fish were subjected to two different water temperatures (15 or 20 °C), with the rest of the rearing parameters remaining identical between the different populations. During the pregrowing phase, the different populations were subjected to four different water-current velocities (WCV), with the rest of the environmental conditions remaining common. At the end of the pregrowing phase (43.5±0.8 mm TL), lordosis was more frequent in fish that developed at 20 °C (pb0.05), independently of the WCVs applied. The anatomic analysis of the deformed fish revealed a significant effect of early developmental temperature on the severity of the deformity, with the 15 °C populations showing the lower severity in respect to the angle of lordosis and the number of affected vertebrae (pb0.05). Two weeks of exposure to WCVs (24.0±0.8 mm TL) resulted in 15 °C populations presenting the lower incidence of lordosis and the higher incidence of normal fish in all WCVs, except 50%, tested (pb0.05). At this stage, WCV had a clear effect on lordosis development in populations coming from both developmental temperatures (pb0.05), although at 15 °C these effects were more pronounced. Fish that developed at 20 °C showed significantly higher incidence of deformed vertebral centra and arches than those developed at 15 °C (pb0.05). These early anatomical signs were evident in samples taken at the end of the larval rearing phase (15.7±1.0 mm TL), as well as 1 week after the onset of exposure to WCVs (21.4±0.6 mm TL). In both cases, their incidence was significantly higher in fish that initially developed at 20 °C than at 15 °C. © 2005 Elsevier B.V. All rights reserved.

Brown meagre Sciaena umbra Linnaeus 1758 is a demersal species living at depths of 0–200 m with a wide distribution in the Mediterranean Sea, Black Sea and eastern Atlantic Ocean. It exhibits nocturnal behavior and occupies bottom caves and seabeds covered with vegetation. This study presents the first data on brown meagre growth under culture conditions and contributes some basic information on its dietary, protein requirement by feeding isoenergetic diets with different protein-lipid ratios by means of self-feeders. Fish with 78.8±15.8 g (mean±standard deviation) body weight were divided into four groups and subjected to four different feeding regimes with three replications for 77 days. In the first group, fish were supplied with a high protein and low fat diet (HPLF, 52∶8 w/w fat-protein ratio), the second one a medium protein and medium fat diet (MPMF, 42∶14), the third with a low protein and high fat diet (LPHF, 31∶23). In the fourth group, fish had access to both HPLF and LPHF diets. Fish fed on HPLF and MPMF diets showed significantly better growth and feed conversion ratios than fish fed on the LPHF diet. Fish with access to HPLF and LPHF diets exhibited comparable growth to the HPLF group but their feed conversion ratio was significantly higher. The condition factor and hepatosomatic index revealed no significant differences between dietary regimes. The liver of brown meagre may serve as a depository organ for energy, judging from its relatively high lipid content (39–43%).

Two bath treatment trials for the control of the monogenean Microcotyle sp. in the gills of cultured red porgy, Pagrus pagrus using formalin (200 ppm for 1 h) and mebendazole (400 ppm for 1 h) were conducted. Formalin was very effective removing all the parasites from the gills of the infected fish while mebendazole produced no significant result. Based on the results of the trial, formalin was selected for the treatment of a large population of heavily infected red porgies held in sea cages. The results of the treatment are discussed.

This study is concerned with the effect of hyrdated diets on growth and feed performance of Dentex dentex. Three levels of dietary water were tested: 7%, 20% and 40%. For the 7% level a commercial feed was used and the 20% and 40% water levels were obtained after adding an appropriate amount of deionized water to the commercial feed and mixing the pellets well. The diets were offered to fish by self-feeders, by which fish were allowed continuous access to diets after acti|vating the self-feeders; by belt feeders, by which the diets were fed continuously and in excess over a 12 h interval; and by hand to apparent satiation two times a day. After 151 days of feeding, the group fed on the 20%-water diet showed significantly (P

This study presents data on the eiect of carotenoid sources on skin coloration of red porgy (Pagrus pagrus). Three experiments were conducted: in the ¢rst, ¢sh were fed an astaxanthin (Naturose s )-supplemented diet, while the second ¢sh received diets supplemented with b-carotene (Rovimix b-caroten s )o r

Species diversification is considered a major approach for the sustainable development of aquaculture. The greater amberjack ( Seriola dumerili ) has particular characteristics–advantages making it an appropriate candidate: high growth rate, large size, and established worldwide market. In the present study, the mesocosm method for larval rearing was applied, since it has been shown to be effective in the larval rearing of several species so far. This method is a semi-intensive technology, based on daily exogenous food addition, but also having the capacity of some endogenous productivity. Greater amberjack eggs were obtained from wild-caught fish matured in captivity in 6 years, after induced spawning with implants containing gonadotropin-releasing hormone agonist (GnRHa). A total of 9800 eggs survived after embryo appearance and were incubated in a 40-m 3 tank with natural seawater of 40 psu. Rearing lasted 40 days. After mouth opening on day 2 post hatching, exogenous feeding with rotifers, Artemia nauplii and inert feed was initiated, while endogenous produced copepods contributed as food for the larvae from day 7 post hatching onwards. During rearing, larvae grew with an exponential rate of 0.073 day −1 in terms of total length (TL), and reached 39.9 ± 5.4 mm and 0.5 ± 0.1 g body weight at the end of the trial. All larvae inflated their swim bladder and completed metamorphosis at about 5 mm and 8 mm TL, respectively. Schooling behavior was first observed when larvae reached 9–10 mm TL, while aggression against the smallest individuals was first noticed the same period. The final population of about 350 individuals (3.5% survival) was transferred at the end of the trial for subsequent on-growing. The results obtained indicate the reliability of the technology for the larval rearing of the greater amberjack, and also its appropriateness for diversification with difficult marine species.

19 pages, 6 figures, 1 table.-- Printed version published Apr 2005., Starting from 66 days post hatching (dph), European sea bass Dicentrarchus labrax were graded successively to create a fast growing (L‐extreme) and a slow growing (S‐extreme) population. The L‐extreme population grew significantly larger (ANOVA, n = 89–101, P < 0·01) attaining twice the wet mass of the S‐extreme population at 300 dph (130·9 ± 1·8 v. 66·7 ± 0·9 g, mean ± s.e.). When the two populations were sexed, the L‐extreme consisted of 96·5% and the S‐extreme of 30·2% females, while the ungraded control had 59·2% females. Sex differentiation began first in females at a total length (LT) of 97 ± 4 mm and wet mass of 9·4 ± 1·2 g (150 dph), and was completed when fish reached 166 ± 6 mm and 53·4 ± 6·4 g (250 dph) in both sexes. Precocious maturation in males was positively correlated to growth. Gonad oestradiol (E2) was significantly higher in the female‐dominant population at the onset of ovarian differentiation (ANOVA, n = 10, P < 0·05) and in the plasma after the appearance of the first primary oocytes (P < 0·01). Gonad testosterone (T) increased in both populations after sex differentiation (ANOVA, n = 10, P < 0·05), while plasma levels were significantly higher in the male‐dominant population (P < 0·001). Both gonad and plasma 11‐keto testosterone (11‐KT) were significantly higher in the male‐dominant population (ANOVA, n = 10, P < 0·01) reaching maximal values at spermiation. The results suggest that E2 is closely related with ovarian differentiation and the onset of oogenesis, while T and 11‐KT is more related to spermatogenesis and precocious maturation., This work was undertaken as part of the research programme ‘Improving production efficiency of sea bass farming by developing methodologies to eliminate environmental androgenesis’, and was supported by a research grant from the European Community to S.Z., C.C.M. and F.P. under the Quality of Life and Management of Living Resources programme (contract Q5RS-2000-31365).

Recu le 8 avril 2004 ; Accepte le 7 octobre 2004 Resume – Une analyse phylogeographique de quinze echantillons de Dicentrarchus labrax dont cinq sont originaires de Mediterranee occidentale, sept de Mediterranee orientale et trois echantillons d’elevage en provenance de trois piscicultures francaises a ete effectuee a partir du polymorphisme de six locus microsatellites. Parmi les echantillons orientaux, trois ne se regroupent pas en fonction de leur origine geographique, mais plutot avec le groupe occidental. Ces echantillons presentent egalement une diversite allelique legerement reduite, indiquant qu’ils proviennent d’un nombre limite de geniteurs d’origine occidentale. Parmi les stocks d’elevage, un seul montre une reduction significative de la variabilite genetique, ce qui indique que ces cheptels sont ouverts et font largement appel a des geniteurs sauvages. L’utilisation d’alevins d’origine occidentale pour ensemencer les premieres fermes d’elevage du bassin oriental remonte au plus tard au debut des annees 80. Ceci souleve la question des mecanismes biologiques expliquant le maintien de poissons d’origine occidentale dans un contexte oriental pendant au moins deux ou trois generations.

In the current paper we present the rearing methodology of common dentex (Dentex dentex), a promising candidate for Mediterranean marine aquaculture, from the larval to the on-growing phase. The results are discussed in terms of the efficiency of rearing methodology followed, for the mass production of the species.

The objective of the current study was to examine the possibility of maturing Mediterranean greater amberjack ( Seriola dumerili ) in culture at two different facilities in Greece and inducing spawning using gonadotropin releasing-hormone agonist (GnRHa) implants. Males in both stocks ( n =8) were in spermiating condition in mid June, though sperm motility was low ranging between 5% and 30%, while motility duration ranged between 2.1 and 2.5 min. Females of the first stock ( n =4) at the same time had ovaries with either primary oocytes or early vitellogenic oocytes at advanced stages of atresia, indicating a failure in oogenesis. On the contrary, the only female of the second stock contained oocytes at all stages of oogenesis, including early final oocyte maturation (FOM; oocyte diameter 650 μm). Implantation with a GnRHa implant induced the first spawn about 36 h later. In the absence of another spawn, a gonadal biopsy was taken 15 days later, indicating the existence of more oocytes at post vitellogenesis and some with almost complete lipid droplet coalescence. A second GnRHa implantation at this time resulted in consecutive egg releases after 36 h, 4 and 5 days, with fertilized eggs only at 36 h and 5 days. The study underlines the existence of important reproductive dysfunctions of greater amberjack in captivity, and demonstrates that GnRHa implants can be used for the induction of multiple spawns of viable eggs.

The osteological ontogeny of Pagellus erythrinus (Linnaeus, 1758) and its temperature-induced plasticity is studied. The ontogeny of the skeleton follows the pattern described in all other Sparidae studied so far: the onset of the ontogeny of the vertebral column and the caudal fin is at 4.3 mm total length (TL) and the completion at 17.6 and 15.4 mm TL, respectively. Dorsal and anal fin development appears at about 5.2 mm TL and completes at 7.5 mm TL. The pelvic are the last fins to develop (7.5–11.5 mm TL). Although the pectorals are the only fins present before first feeding, their ontogeny is completed only after 12.0 mm TL. Temperature affects the developmental rate of the skeleton giving as much as 10.9% of differentiation in total length between 16 and 21 °C (caudal lepidotrichia), 9.2% between 16 and 18 °C (caudal lepidotrichia) and 6.7% between 18 and 21 °C (pelvic lepidotrichia). The role of temperature in developmental plasticity is enhanced by the induction of abnormalities mainly in the area of the caudal fin, which reached (in total) 75% occurrence in the higher temperature regime (23 °C) tested. The results of the skeletal ontogeny are compared with the pattern of development of the Sparidae, and are discussed in respect to the role of temperature in the developmental plasticity of fish.

This study is concerned with the investigation of feed preference in juvenile sharp snout seabream (Diplodus puntazzo). Three isoenergetic diets, high protein–low fat (HPLF), medium protein and fat (MPMF) and high fat–low protein (LPHF) were tested using six feeding regimes. Three groups of fish were used as controls to test the diets independently, while to the other three, a different diet combination was provided (HPLF–MPMF, MPMF–LPHF and HPLF–LPHF). Diets were provided by means of one or two self-feeders and fish had continuous access to one or two diets. Fish had an initial weight of 11.1±3.8 g (mean±S.D.) and after 45 days of feeding, no significant differences (P

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.

Pagrus pagrus is one of the promising species for the industry in the Mediterranean but its rearing is still far from satisfactory. In the present work, the conditions and results of larval rearing with the use of an automatic feeding system are presented. Eight populations were reared for 20 days with the ‘pseudo green water’ methodology in two successive trials. Larvae were fed enriched rotifers during the entire rearing period, a mixed diet of rotifers and Artemia (Instar I when larvae reached 5 mm in length, replaced by Instar II after larvae reached 5.5 mm) and a formulated diet (after day 16 post hatching). A computerized system for feeding management was used. A total of 388,000 eggs were incubated and after 20 days, 237,973 larvae (TL = 6.96 ± 0.17 mm) were produced with a survival rate of 61.4 ± 6.3%. Individuals grew in terms of wet weight with an exponential rate of 0.167 ± 0.008 daily (R2= 0.983) with no variations between replicates. Mean individual daily consumption at first feeding (day 4-post hatching), was 0.20 ± 0.06 mg of food (0.03 ± 0.01 dry weight), that is, 180–300 rotifers, while on day 20, consumption increased by 10 (2.081 ± 0.106 mg and 0.276 ± 0.014 in wet and dry weight, respectively). When compared with sea bream, consumption was higher by approximately 3–4-fold. The mean food conversion ratio of the experimental period was 4. In comparison with sea bream larviculture, food consumption of red porgy is higher, and a different feeding strategy is required to satisfy the requirements of the larvae.

Wreckfish (Polyprion americanus) is a panoceanic, antitropical distributed species. Despite the high market price, high growth rate, good quality flesh and the potential for aquaculture, research data are scarce. In this study, the growth performance and food intake was investigated in juvenile fish, while gametogenesis was studied in adult fish. Three groups were created from 19 individuals, which were collected during neustonic sampling, using fish aggregating devices, in association with floating objects and during tuna fishing with drift nets from Greece (Crete), Italy (Ionian Sea) and the Atlantic coast of France from September 1999 to March 2001. All individuals (initial weight between 0.5 g and 4.5 kg) were reared in aquaculture facilities so as to monitor growth performance and food intake. Food (de-frozen fish – bogue, mackerel and squid – or moist pellets) was delivered ad libitum. Total length and wet weight were measured regularly. Daily food intake, the food conversion index and daily growth rate were calculated. Individuals, aging 0+, grew exceptionally fast, reaching 2.0 kg (total length 50 cm) in 12 months and 5.0 kg (total length 65 cm) in 24, while at later stages, the growth rate decreased and depended on the water temperature during rearing. Food consumption varied during the rearing period according to the developmental stage and the rearing conditions. The food conversion ratio ranged between 0.9 and 2.5 on dry weight basis during the period of the study. Gametogenesis was monitored in a separate stock of 15 individuals (11.7 ± 3.7 kg) by biopsis while blood samples were taken for steroid estimation. Increased oocyte diameter was observed in females from August to January, while plasma estradiol levels also increased from October to March. However, neither egg or sperm were collected from the stock. Young wreckfish presented a high growth rate in captivity, thus supporting the feasibility of the species for rearing. Further research, however, is required for the reproduction of the species.