Benthic Recovery after the Cessation of a Gilt‐head Seabream,Sparus aurata,Farm in the Mediterranean Sea

An environmental recovery study was carried out after the cessation of a gilt‐head seabream farm off the Mediterranean coast of Spain. Physicochemical variables of sediments, in situ benthic fluxes of oxygen and nutrients, and benthic macrofauna were measured in the farming area and at a control station. Five sampling campaigns were done, one before the closure and the others at 1, 3, 9, and 24 mo after cessation. Benthic flux of ammonium was the first variable to recover, followed by benthic fluxes of phosphate and dissolved oxygen and percentage organic matter in the sediments, which 3 mo after the cessation of farming already showed levels similar to those in the control station. Nine months after cessation, the other abiotic variables of the sediments disturbed by the activity had recovered, such as percentage coarse fraction, total phosphorus concentrations, and redox potential measurements. The recovery of the macrofauna was slower than the abiotic variables. Three months after cessation, Capitella capitata abundance had reduced drastically in the farming area, but similar specific richness levels were not observed between the two sampled zones until 2 yr after farming cessation.     

Accumulation of Mycosporine‐like Amino Acids in Asparagopsis armata Grown in Tanks with Fishpond Effluents of Gilthead Sea Bream,Sparus aurata

Abstract.— The accumulation of ultraviolet (UV)‐screen substances, mycosporine‐like amino acids (MAAs), in the tetrasporophytic phase of the red alga Asparagopsis armata grown in fishpond effluents of gilthead sea bream, Sparus aurata, is analyzed. Both the effects of total ammonium nitrogen (TAN) fluxes and the algal densities on MAA accumulation were investigated. MAAs increased with the TAN flux, but only until values lower than 100 μM/h. Above this flux, the MAA content decreased, whereas algal yield increased. The content of individual MAAs was related to nitrogen (N) status, that is, shinorine percentage slightly decreased and palythine increased with increasing N fluxes. The decrease of MAAs at high flux of N (up to 100 μM/h) is related to the decrease of water residence time and the decrease of the biofiltration efficiency. Under different TAN fluxes and algal densities, MAA content was negatively related to algal yield indicating that MAAs were accumulated only under a high ammonium‐N availability. Thus, an energy allocation between growth (primary metabolism) and MAA accumulation (secondary metabolism) is regulated by the absorption capacity of inorganic N. In conclusion, A. armata, in addition to its high biofiltration capacity of nutrients, is a good source of MAAs as potential UV screen photoprotectors.     

Effects of Restricted Feeding Regimes on Growth and Feed Utilization of Juvenile Gilthead Sea Bream, Sparus aurata

The effect of restricted feeding on growth, feed efficiency, and body composition was studied in juveniles of gilthead sea bream, Sparus aurata. Juveniles (6.4 g) were stocked into 12 tanks at a density of 16 fish per tank. Four different feeding schedules were tested on triplicate groups of juvenile fish: (1) control fed for 48 d without deprivation, (2) starvation for 1 d and then refed for 2 d (S1), (3) 50% satiation for 2 d and then refed to apparent satiation for 2 d (R2), and (4) 50% satiation for 6 d and then refed to apparent satiation for another 6 d (R6). Results indicated that all fish subjected to cycled restricted feeding regimes were unable to achieve catching up with control group. The specific growth rate of fish in the control was significantly higher than those in S1, R2, and R6, which were not significantly different from each other. Protein efficiency and protein productive value were significantly higher in R2 compared to control, S1, and R6. Fish in R2 had lowest feed conversion ratio (1.12) compared to the control (1.17). Body protein composition in R6 was less than that of the control, S1, and R2, while moisture, lipid, and ash content were not significantly different compared to the control.     

Acute Toxicity of Ammonia and Nitrite to Sea Bream,Sparus aurata (Linnaeus, 1758), in Relation to Salinity

Sea bream, Sparus aurata, is one of the most important fish species that is commonly cultured in the Mediterranean and the eastern coasts of the Atlantic Ocean. The life cycle of sea bream in its natural habitat passes through hyposaline and hypersaline lagoons. It is important to determine the tolerance of the fish to nitrogenous compounds for aquaculture at maximum stocking densities. In the present study, a series of acute experiments were performed to evaluate the effect of salinity on ammonia and nitrite toxicity to sea bream. The fish were exposed to different ammonia and nitrite concentrations according to the static renewal methodology at three different salinities (10, 20, and 30 ppt) and at a temperature of 20 C and a pH of 8.2. The toxic effect of total ammonia nitrogen (TAN) and nitrite nitrogen (NO₂‐N) decreased with increasing salinity levels (P < 0.001). Acute toxicity (96‐h lethal concentration 50 [LC₅₀]) values of TAN were determined to be 5.93, 11.72, and 19.38 mg/L at 10, 20, and 30 ppt salinity, respectively. The 96‐h LC₅₀ values of NO₂‐N were determined to be 370.80, 619.47, and 806.33 mg/L at 10, 20, and 30 ppt salinity, respectively. Results indicate that sea bream is less tolerant to ammonia but more tolerant to nitrite compared with some other fish species.     

Combined Effects of Cycled Starvation and Feeding Frequency on Growth and Oxygen Consumption of Gilthead Sea Bream,Sparus aurata

Triplicate groups of gilthead sea bream, Sparus aurata (10.4 g), were distributed among 27 tanks (12 fish per tank) and reared in flow‐through seawater. A factorial experiment (3 × 3) was designed to include a continuously fed control group and two cycled starvation groups: 1 + 3 (starved 1 d, fed 3 d), 1 + 5 (starved 1 d, fed 5 d). Each of the feeding groups was subjected to one of three feeding frequencies (2, 4, and 6 times per day) over the 60‐d experiment duration. The average final weight of fish in 1 + 3 and 1 + 5 groups were significantly lower than that of the control group. Partial compensation was observed in the starved groups subjected to any of the three feeding frequencies. Regardless of the feeding frequency, control fish consumed less feed than the starved groups. The highest body protein content was found in the control group. The rate of oxygen consumption significantly increased 30 min after the feeding and the magnitude of the effect increased with the feeding frequency. These results suggest that the present cycling starvation schedules did not invoke a full compensation in gilthead sea bream.     

Growth, Survival and Feed Conversion Rates of Sea Bream (Sparus aurata) Cultured in Earthen Brackish Water Ponds Fed Different Feed Types

Sparus aurata were cultured during an 8-month period in brackish water (salinity about 25 ppt) in an extensive culture system comprising eight earthen ponds, each with a water surface of 2.1 ha. Initial mean wet weight of fish in all ponds varied from 13.6 ± 1.9 to 19.2 ± 2.6 g/fish. The eight ponds were randomly allocated one of four experimental treatments (two ponds/treatment). In the first treatment, ponds were fertilized monthly with 100 kg urea and 50 kg triple super phosphate. The other treatments (2–4) were fed a locally produced tilapia pellet feed containing 25% crude protein made using different processes. Fish in the second treatment were fed tilapia feed pelleted by compressing machine, whereas in treatments 3 and 4 the pellets were produced by extruder machine (Wenger). Pellets in treatment 3 were floating and in the fourth were semi-sinking. Fish were fed pellets twice daily at 6% of their biomass. The mean final body weight for each treatment respectively was 104.6, 118.9, 156.8 and 158 g. Specific growth rate (SGR) of 0.8, 0.79, 0.99 and 0.95%/day, were obtained in ponds using only inorganic fertilizer, compressed sinking pellets, extruded floating pellets and extruded semi-sinking pellets, respectively. Feed conversion ratios (FCR) for treatments with the extruded tilapia pellets were 2.2 and 2.6 g feed/g gain, which were significantly (P < 0.05) better than treatments with compressed pellets (3.2 g feed/g gain). Production/ha/year were 1389, 1358, 945 and 682 kg fish for the groups fed with extruded floating, extruded semi-sinking, compressed and natural food, respectively. Under the present experimental circumstances, Sparus aurata fed extruded floating tilapia pellets (25% crude protein and 2,600 kcal/g), showed the best productive performance.     

Effects of Fish Meal Replacement by a Soybean Protein on Growth,Histology, Selected Immune and Oxidative Status Markers of Gilthead Sea Bream,Sparus aurata

The purpose of the trial was to study the impact of a 6‐mo dietary administration of soybean protein on growth, liver and intestine morphology, immune response, and oxidative stress in gilthead sea bream. The immune response was evaluated by performing immunological assays in blood, head kidney (HK), or serum (respiratory burst activity [RBA], myeloperoxidase content and bacteriolytic activity) and gene expression analysis of immune‐associated genes (MHCIIα [major histocompatibility complex IIα], β2m [β‐2‐microglobulin], CSF‐1R [colony‐stimulating factor‐1 receptor], NCCRP‐1 [nonspecific cytotoxic cell receptor protein 1], TGF‐β1 [transforming growth factor beta‐1], and HSP70 [heat‐shock protein 70]) in HK and intestine. Oxidative stress was evaluated by measuring the activity of liver enzymes associated with antioxidant system. The soybean protein was administrated in the diets at 20, 40, and 60% levels and its effects were evaluated compared with a fish meal diet. Growth and feed efficiency were affected negatively from 40% level. Increased RBA and expression levels of TGF‐β1 and β2m were found in HK only at 40% level. In intestine, at 60% level CSF‐1R expression was upregulated and some signs of inflammation were evident. In liver, at 60% level lipid accumulation in hepatocytes was observed and enzyme activity was increased. Dietary administration of soybean protein indicated changes from 40% in growth and immune response, and exerted an antioxidative effect at 60% level.     

Phytic Acid‐Induced Inhibition of Digestive Protease and α‐Amylase in Three Indian Major Carps: An in vitro Study

Antinutritional effects of phytic acid (myoinositol hexaphosphate, IP6) on growth and digestibility in fish have been reported. However, specific effect of IP6 on the digestive enzymes in fish has not been addressed. In this study, inhibitory effect of synthetic IP6 (Phytic acid sodium salt, 90% purity) on the activity of the digestive protease and α‐amylase in rohu, Labeo rohita; catla, Catla catla; and mrigal, Cirrhinus mrigala has been investigated in vitro. Graded levels (12.5, 25, 50, 100, 150, and 200 µg/mL) of IP6 were added to the reaction mixtures containing enzyme extracts and substrate solution in triplicate to detect any change in enzyme activity. Results of the experiment revealed that IP6 significantly inhibit/lower activities of the digestive enzymes in a dose‐dependent manner, as evident from the regression equations (F values significant at P < 0.001 level). Apparently, irrespective of the fish species studied IP6‐induced inhibition of α‐amylase activity was greater than protease activity. Among the three fish species studied, C. mrigala appeared to be more sensitive to IP6 for both α‐amylase and protease activity. Enzyme activity was least affected in C. catla. Results of the study might raise concern while incorporating IP6 rich plant‐derived feed ingredients in aqua feed preparation.     

仿刺参消化道的组织学及其4种消化酶活力的周年变化

2004年11月—2005年10月的每月中旬,在大连黑石礁海区采捕体长(21.8±2.3)cm(麻醉状态下),体质量(165.307±3.521)g的仿刺参,测定消化道中蛋白酶、淀粉酶、褐藻酸酶和纤维素酶活性的周年变化,观察其组织学结构。试验结果表明,1—5月,消化管的最大长度可达体长的4.6~5.9倍,2月达全年的最大值;蛋白酶、淀粉酶和褐藻酸酶的活力随水温的升高而增加,4—5月达最大值;之后,消化管长/体长比逐渐下降,8—10月上旬,消化管长仅为体长的0.8~1.1倍,酶活力逐渐下降;10月中下旬,随着水温的下降,消化管长/体长比又快速增大,酶活力逐渐回升。纤维素酶的活力全年一直很低,周年变化不明显。消化道管壁的黏膜层为单层或假复层上皮,主要由柱状细胞、立方细胞和一些腺细胞组成。黏膜下层为一层疏松结缔组织。肌肉层由外环行、内纵行的两层平滑肌细胞组成。浆膜层由薄层结缔组织和扁平细胞构成。     

Parasitic infections of sea bass,Dicentrarchus labrax,and gilt head sea bream,Sparus aurata,in mariculture facilities in France

Parasitic infections occur in sea cultured Sparus aurata and Dicentrarchus labrax in France. Investigations indicate the presence of parasitic protozoans, monogeneans and copepods in these fish.     

Biochemical parameters in the blood of gilthead sea bream (Sparus aurata Linnaeus, 1758) supplemented with commercially available β‐glucan‐based product (IMUNO‐2865®)

The aim of this study was to evaluate the effects of a promising new immune stimulant in aquaculture (IMUNO‐2865^®) on biochemical parameters in sea bream during the winter stress period. A total of 640 sea bream were fed throughout 90 days with diets containing 0 (Group 1), 1 (Group 2), 10 (Group 3) and 25 g (Group 4) of IMUNO‐2865^® kg^?1 of feed. Samples were taken each month and 90 days after supplementation. No statistical differences among treatment groups were noticed for the following biochemical parameters: glucose (GLU), aspartate aminotransferase (AST), plasma cholesterol (CHOL), lactate dehydrogenase (LDH), urea (URE) and creatinine (CREA). At the final sampling, total ammonia (NH₃) was higher in Groups 3 and 4 compared to the control and the low supplementation group (p < .05), while total proteins (TP) was significantly higher in Group 4 compared to all other groups, and in Groups 2 and 3 compared to the control group (p < .05). Blood Ca⁺⁺ levels were significantly higher after 60 days of feeding in all treatment groups compared to the control, and remained elevated in Group 4 even after 90 days following cessation of supplementation (p < .05). The results of this study described the increase of biochemical parameters in the blood of sea bream after use of IMUNO‐2865^® but future research is needed to evaluate its potentially immunostimulative effect on fish in commercial aquaculture.     

Debaryomyces hansenii L2‐enriched diet enhances the immunity status,gene expression and intestine functionality in gilthead seabream (Sparus aurata L.)

This study evaluates the effects of the dietary administration of the live yeast Debaryomyces hansenii strain L2 on the immune responses of gilthead seabream for 4 weeks. Cellular immune parameters were measured from serum and head‐kidney leucocytes respectively. The expression levels of immune‐associated genes were quantified by real‐time polymerase chain reaction. In addition, the profile of intestinal microbiota was studied by denaturing gradient gel electrophoresis. The results showed that seabream fed a diet containing D. hansenii had significantly increased cellular immune parameters. The yeast‐supplemented diet up‐regulated the expression of most seabream genes at week 2 and down‐regulated all of them at week 4, except in the head‐kidney. Finally, a reduction in the diversity of the intestinal microbiota was detected in those specimens receiving the yeast‐supplemented diet. These results support the idea that the live yeast D. hansenii strain L2 stimulates the immune system of gilthead seabream.     

Observations on the increase of wild gilthead seabream,Sparus aurata abundance,in the eastern Adriatic Sea: problems and opportunities

The recent increase of the local population of gilthead seabream, Sparus aurata, in three areas along the southeastern Adriatic Sea: Malostonski Bay (Croatia and Bosnia and Herzegovina), Neretva Estuary (Croatia) and Boka Kotorska Bay (Montenegro) and its adverse effects on shellfish culture by preying on Mediterranean mussels, Mytilus galloprovincialis, and the European flat oyster, Ostrea edulis, are studied. The results from the analysis of the existing information show that the main reason for the recent increase is the escapes from local fish farm which enrich the local population constantly with new gilthead sea bream. The existence of practically endless food in the area of the shellfish farms allows the concentration of the population in the region instead of its dispersion along the Adriatic coast. Moreover, ecological analysis indicates that the gilthead seabream is facing a very low competition from other local species which enhances its capacity to further populate the region. While the impact on the ecosystem is not yet known, the socio-economic impact of the increase of the gilthead seabream population is evident today. Many shellfish farms are closing today in the region since the damages may reach over 90 % of the production.     

Annual variations of the plasmatic levels of glucose and amino acid and daily changes under different natural conditions of temperature and photoperiod in Gilthead Sea bream (Sparus aurata, L.)

Daily and annual changes in the plasmatic glucose and amino acid concentration have been determined in Sparus aurata L. Fish (average weight 330 g) were kept in cages under natural conditions of temperature and photoperiod and fed with a commercial diet. The months studied were chosen to establish whether there is any influence on the plasmatic glucose and amino acid concentration due to the change in temperature and photoperiod (equal photoperiod and different temperature, March and October; different photoperiod and equal temperature, May and November; and different photoperiod and temperature, June and January). To study the daily profile of glucose and amino acids concentrations, blood was extracted from six fish every 3 h during 24 h. Annual changes were determined as the average of the samples obtained during 1 day. Results show an annual rhythm with acrophase in June with a positive correlation with photoperiod for glucose and amino acids and with temperature only for amino acids. Daily profiles are rhythmical with a period of 24 h except in November with a period of 8 h for amino acids.     

Effect of phytase supplementation of a plant‐based diet on phosphorus and nitrogen bioavailability in sea bream Sparus aurata

To assess to what extent addition of phytase to a plant‐based diet results in spatio‐temporal changes of phytate, available P, soluble protein, total amino acids and the activity of the main digestive proteases in gilthead sea bream, fish were fed two plant‐based diets with or without phytase. Stomach, proximal intestine and distal intestine contents were monitored for these parameters at 0, 1, 2, 4 and 6 h after feeding. A reduction (P < 0.0001) of the soluble P–IP6 in the stomach when phytase was added to the diet was observed. Within stomach, most of the total P–IP6 was precipitated (86%), possibly due to the low acidification capacity of the sea bream (pH > 4), but 57% of the dietary P–IP6 was dephosphorylated, suggesting that phytase could have the capacity to dephosphorylate insoluble IP6 at such pH. An increment (60%) (P < 0.01) in total gastric protease activity was observed by phytase addition, this being the first demonstration of the in vivo effect of IP6 on the pepsin activity in fish stomach. Gastric pH and residence time of the digesta inside the stomach are critical factors for an efficient phytase action and improve P and N bioavailability in plant‐based diets used in fish aquaculture.     

Effects of Dietary Taurine on the Growth,Digestive Enzymes,and Antioxidant Capacity in Juvenile Sea Cucumber,Apostichopus japonicus

Taurine has been widely used as a growth‐ or health‐promoting additive in aquatic animals because of its multiple functions, while little work has been done on its effects on sea cucumbers, in spite of the occurrence of serious diseases. In this study, juvenile sea cucumbers (4.68 ± 0.04 g) were fed diets supplemented with taurine at 0% (control), 0.1, 0.25, 0.5, 1, and 2% for 8 wk. At the end of an 8‐wk feeding trial, growth performance of sea cucumbers was not significantly affected by dietary taurine (P > 0.05). However, dietary taurine significantly elevated intestinal lipase activities of sea cucumbers (P < 0.05). Intestinal amylase activity and trypsin activity in sea cucumbers did not show significant changes after animals were fed diets supplemented with taurine (P > 0.05). Dietary taurine at all five dosages significantly increased total antioxidant capacity in sea cucumbers, while superoxide dismutase activity in groups with dietary taurine at 0.25 and 0.5% was significantly higher than that of the control group (P < 0.05). Therefore, it appears that taurine could be used as a potential feed additive to confer better health of farmed sea cucumbers.     

Scaling of body‐shape quality in reared gilthead seabream Sparus aurata L. Consumer preference assessment,wild standard and variability in reared phenotype

In this study, a scale of quality for the body shape of Gilthead seabream was developed. For this purpose, a questionnaire survey was carried out to study the preferences of consumers for the body shape of seabream. Furthermore, the variation in body shape in reared seabream was studied under two rearing environments (sea cages vs. tanks) and in comparison with wild‐caught individuals. Following the test–retest analysis of reliability, the 22 of 65 participants in the survey presented a significant correlation between repeated evaluations of the same subjects and were classified as responders of high discrimination efficiency or/and reliability (HDR). Geometric morphometric analysis on the evaluation of HDR responders revealed that compared with the fish of fair body shape, fish with preferred body shape were characterized mainly by a more proximal position of the base of the pelvic fins, the anterior base of the anal fin and the anterior dorsal fin. Of the 45 wild‐caught specimens examined, 26 presented a normal lateral line and no obvious skeletal deformities. The body shape of the normal wild‐caught fish was compared with the shape of reared seabream. Results showed that both the origin of fish (wild vs. reared) and the rearing methodology during the on‐growing phase significantly affected the body shape of seabream (P < 0.001). Compared with the reared fish, the wild‐caught fish were characterized mainly by a less prominent belly, slender trunk, smaller head, shorter caudal peduncle and a more posterior‐ventral position of the upper jaw.     

Organic,inorganic and nanoparticles of Se,Zn and Mn in early weaning diets for gilthead seabream (Sparus aurata; Linnaeus, 1758)

Levels of the oxidative stress‐related minerals selenium (Se), zinc (Zn) and manganese (Mn) that should be supplied in microdiets for marine fish larvae depend on the availability of the molecular form of these minerals. The objective of this study was to determine how effectively Se, Zn and Mn in organic, inorganic and nanoparticle forms promote larval performance and bone development. Microdiets supplemented with Se, Zn and Mn were fed for 24 days to 20 dah seabream larvae. Microdiets without Se, Zn and Mn supplementation were associated with poor growth, low bone mineralization and a high incidence of anomalies in the branchial arches. Including Zn, Mn and Se in an amino acid chelate organic form promoted maximum larval growth, increased body lipid reserves, enhanced early mineralization and prevented branchial arches anomalies. In contrast, feeding with inorganic forms of these minerals was less effective than organic minerals in improving larval weight or bone mineralization in comparison to the non‐supplemented diet. Moreover, the larvae were less resistant to stress, and fish showed higher bone anomalies in the pre‐hemal region. Adding Zn, Mn and Se in the form of nanometals did not enhance growth, but improved stress resistance and bone mineralization. The study showed the need to supplement seabream with early weaning diets based on squid meal and krill oil with one or more of the antioxidant minerals, to promote larval growth, bone mineralization and prevention of skeleton anomalies, organic minerals being more effective than inorganic forms and nanometals in promoting mineralization and stress resistance.     

饲料中添加浒苔对仿刺参幼参生长、消化酶活性和免疫力的影响

在水温17~18℃和盐度30条件下,将初始体质量为(4.09±0.26)g的仿刺参饲养在15个循环水玻璃缸(容积100L)中,投喂在基础饲料中添加0%、3%、6%、9%和12%浒苔的饲料,于投喂后第7、14、28d和42d分别检测仿刺参的生长指标、消化酶(蛋白酶、淀粉酶、纤维素酶和褐藻酸酶)和体腔液免疫酶(溶菌酶、酸性磷酸酶、碱性磷酸酶和超氧化物歧化酶)的活性。试验结果表明,投喂试验饲料后第14、28d和42d:(1)饲料中添加6%和9%浒苔组仿刺参的特定生长率显著增加(P0.05),在不同取样时间其他添加组仿刺参的的特定生长率与对照组差异不显著(P0.05);(2)饲料中浒苔添加量为6%和9%试验组仿刺参的4种消化酶比活力显著高于对照组(P0.05),其中6%组仿刺参的消化酶比活力最高;(3)饲料中浒苔添加量为6%时,仿刺参溶菌酶活力显著高于对照组及其他试验组(P0.05);饲料中浒苔添加量为6%和9%时,仿刺参碱性磷酸酶活力和超氧化物歧化酶活力显著高于对照组及其他试验组(P0.05);添加浒苔可以显著提高酸性磷酸酶活力,至第42d,试验组酸性磷酸酶活力高于对照组(P0.05),且浒苔添加量为6%时活力最高。在本试验条件下,饲料中添加浒苔可以提高仿刺参的特定生长率、消化酶活力及免疫力,浒苔的最适添加量为6%~9%。