Effect of light intensity and photoperiod on Nile tilapia Oreochromis niloticus L. seed production

The objective of this study was to compare the effect of six light intensity/photoperiod combinations (2500 lux/18 h, 2500 lux/15 h, 2500 lux/12 h, 500 lux/18 h, 500 lux/15 h and 500 lux/12 h) on seed production in the Nile tilapia Oreochromis niloticus L. Each combination represented a treatment and was triplicated in 0.4‐m³ fibreglass tanks within a recirculating water system. Water temperature was maintained at 29.0 ± 1.0 °C. Males and females with mean body weights of 116.8 and 91.6 g, respectively, were stocked at a rate of eight fish/tank with a male to female ratio of 1:3. Seeds (eggs, sac fry and swim‐up fry) were collected every 2 weeks. The experiment lasted for a total of 120 days. The results showed that the 2500 lux/18 h treatment produced significantly greater (P < 0.05) total seed/tank (4944), seed kg^?1 female day^?1 (50.9), seed m^?2 day^?1 (40.3) and seed/ female day^?1 (6.7) than treatments with medium or short photoperiods (15 and 12 h day^?1 respectively) or lower light intensity (500 lux). The degree of spawning synchrony and percentage of the sac and swim‐up fry stages were significantly higher in the 2500 lux/18 h treatment than in the other treatments. Under the conditions tested in this study, seed production and spawning synchrony in the Nile tilapia may be improved by subjecting breeders to a light intensity of 2500 lux and a photoperiod of 18 h day^?1.     

Chlorella vulgaris meal improved growth performance,digestive enzyme activities,fatty acid composition and tolerance of hypoxia and ammonia stress in juvenile Pacific white shrimp Litopenaeus vannamei

This study was conducted to investigate the effectiveness of fish meal substitution by Chlorella vulgaris meal in the diet of Pacific white shrimp, Litopenaeus vannamei. Experimental diets contained varying levels of fish meal (400, 300, 200, 100 and 0 g/kg) which was replaced by increasing levels of C. vulgaris (0, 97.2, 194.4, 291.6 and 388.8 g/kg). After 8 weeks of feeding trial, shrimp fed diet with 97.2 g/kg C. vulgaris showed significantly improved growth compared to other treatments including control. Similarly, shrimp fed diet with 97.2 g/kg C. vulgaris showed significantly higher amount of trypsin and amylase activities compared to other treatments. The contents of long‐chain polyunsaturated fatty acids including eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid were significantly higher in the whole body of L. vannamei fed with different levels of C. vulgaris compared to those of control group. After exposure to hypoxia, the survival rate of shrimp fed diets contained different levels of C. vulgaris was higher than that of control group, while no significant differences were observed in ammonia tolerance among treatments. In conclusion, this study indicated that fish meal can be completely replaced with C. vulgaris in the diet of juvenile L. vannamei with no adverse effects on the performance of shrimp.     

The effect of photoperiod, tank colour and light intensity on growth of larval haddock

In two separate experiments, haddock (Melanogrammus aeglefinus) larvae were raised under different photoperiods (24L : 0D or 15L : 9D), or different combinations of tank colour (black or white) and light intensity (1.1 mol s^–1 m^–2 or 18 mol s^–1 m^–2). Growth (0.8% day^–1 in standard length; 2.9% day^–1 in body area) and survival (2%) were not significantly different between photoperiod treatments after 35 days. Larval survival was greater in white versus black tanks after 41 days (2% versus l%, respectively). Growth of larvae was impaired in black tanks at low (1.1 mol s^–1 m^–2) light intensity (0.8% day^–1 in standard length and 2.2% day^–1 in body area versus 1.1% day 21 in standard length and 3.1% day^–1 in body area, for all other treatments). Transmission and reflection of light was low in black tanks at low incident light, and there was very little upwelling light. The resultant poor prey to background contrast probably resulted in larvae being unable to consume sufficient food to sustain a level of growth comparable to that in other treatments.     

Growth and fatty acid composition of juvenile Cerastoderma edule (L.) fed live microalgae diets with different fatty acid profiles

The importance of dietary 20:5n‐3 (EPA), 22:6n‐3 (DHA) and 20:4n‐6 (ARA) for growth, survival and fatty acid composition of juvenile cockles (Cerastoderma edule) was investigated. Cockles of 6.24 ± 0.04 mm and 66.14 ± 0.34 mg (live weight) were distributed into three treatments where live microalgae diets were fed constantly below the pseudofaeces production threshold, for three weeks. Diets had distinct fatty acid profiles: high EPA (53% Chaetoceros muelleri + 47% Pyramimonas parkeae), no DHA (47% Brachiomonas submarina + 53% Tetraselmis suecica) and low ARA concentrations (73% P. parkeae + 27% Phaeodactylum tricornutum). Growth was positively affected by high EPA and low ARA diets, whereas no significant growth was observed for the no DHA diet. High mortality of cockles fed no DHA diet raises questions about its suitability for cockles. In balanced diets with EPA and DHA, lower concentrations of ARA do not limit growth. The impact of dietary fatty acids was evident in the fatty acids of neutral and polar lipids of cockles. In polar lipids of all cockles, there was a decrease in EPA, in contrast to an increase in DHA. The combination of EPA and DHA in a live microalgae diet was beneficial for the growth and survival of juvenile cockles.     

Effects of dietary docosahexaenoic acid sources,microalgae meal and oil,on growth,fatty acid composition and docosahexaenoic acid retention of orange‐spotted grouper,Epinephelus coioides

This study evaluated the effects of Aurantiochytrium spp. microalgae meal and oil as dietary docosahexaenoic acid (DHA) sources on the growth, fatty acid composition and DHA retention of orange‐spotted grouper, Epinephelus coioides. Dietary fish oil was replaced with microalgae meal or oil to provide an equal amount of DHA as a fish oil‐containing basal diet. In total, three experimental diets were fed to triplicate groups of fish (initial wt: 8.48 ± 0.06 g) in a recirculating system for 8 weeks. The weight gain and feed efficiency of the fish did not differ significantly among the experimental diets. The fatty acid composition of the whole body of the fish generally reflected the composition of their diet. The concentration of eicosapentaenoic acid in the whole body was higher in the fish fed the fish meal control diet than in those fed the two experimental diets The fish fed the control diet and those fed the diet containing microalgae oil exhibited higher DHA concentrations than did the fish fed the diet containing microalgae meal. The whole‐body DHA retention was the highest in the fish fed the diet with microalgae oil, followed by the fish fed the control diet. The lowest whole‐body DHA retention was observed in the fish fed the diet containing microalgae meal. The results suggested that the oil from Aurantiochytrium spp. microalgae can be used as DHA source for the grouper. DHA utilization by the fish was higher when the diet was supplemented with microalgae oil than with dry microalgae meal.     

温度、光照强度和光照周期对铜藻有机碳释放速率的影响

为探究铜藻(Sargassum horneri)的有机碳释放速率、与净初级生产力(NPP)之间的关系及主要的调控因素等问题,本研究采用三变量三水平的正交实验,测定铜藻在不同温度(5、15和25℃)、光照[86、172和258 μmol/(m2·s)]和光照周期(L∶D=6 h∶18 h、L∶D=12 h∶12 h、L∶D=24 h∶0 h,L表示光照时长,D表示黑暗时长)条件下溶解有机碳(DOC)、颗粒有机碳(POC)的释放速率和初级生产力。结果显示,DOC和POC释放速率的范围分别为0.653~4.785 mg/(g·h)和0.066~0.322 mg/(g·h);温度和光照强度分别是铜藻释放DOC和POC的主要调控因素;铜藻在高温、中光、L∶D=6 h∶18 h条件下的DOC释放速率最高[4.785 mg/(g·h)],在高温、高光、L∶D=24 h∶0 h条件下的POC释放速率最高[0.322 mg/(g·h)];铜藻释放的DOC和POC占NPP的比值分别为4%~130%和0.4%~5.9%;DOC释放速率与NPP之间存在负相关关系,POC释放速率与NPP之间无明显相关性。研究结果为深入了解铜藻的生理生态学特性及其对沿海生态系统碳循环的影响提供了科技支撑。     

不同营养盐对小球藻(Chlorella vulgaris Beij.) 培养的影响

在25℃,光照4,5001x的条件下,通过正交实验的方法考察不同浓度的C、N、P营养盐配方对小球藻生长及胞内多糖含量的影响.结果表明利于小球藻生长,胞内多糖含量积累的营养元素的优化组合分别为NaHCO30.15g/l、NaNO30.15g/l、NaH2PO40.012g/l;NaHCO30.10g/l、NaNO30.30g/l、NaH2PO40.006g/l.微量元素和维生素的加入量同f/2配方中的量.与之对应的细胞密度为3.7×107个细胞/ml;多糖含量为12.527mg/cell.     

海洋微藻多不饱和脂肪酸研究进展

多不饱和脂肪酸在人和动物的生理活动中具有重要的作用.海洋微藻中富含多不饱和脂肪酸.因此,利用海洋微藻生产多不饱和脂肪酸具有广阔的前景.本文综述了温度、光辐射、培养液的化学组成、通气量、存贮和培养方式等环境影响因子对海洋微藻中多不饱和脂肪酸含量的影响,以及利用光生物反应器培养微藻的现状,为后续的研究奠定了理论基础.     

Effect of light,temperature and diet on the fatty acid profile of the tropical sea anemone Aiptasia pallida

Sea anemones of the genus Aiptasia are used as biological models for research and as a prey for the culture of the highly priced ornamental nudibranch Aeolidiella stephanieae. Symbiotic Aiptasia display a remarkable trophic plasticity, being able to fulfil their energetic demands heterotrophically and autotrophically. Consequently, they display a highly variable fatty acid (FA) profile. The objective of the present study was to analyse how light regime (12 h light : 12 h dark versus 24 h darkness), water temperature (22 versus 26 °C) and diet (Artemia nauplii versus enriched Artemia metanauplii) affect the FA composition of A. pallida. The FA profile of wild specimens was also analysed. The dominant FAs of cultured A. pallida were 16:0, 18:1n‐9 and 22:6n‐3. Higher FA levels were recorded when anemones were exposed to light, with this factor explaining the largest amount of variation in the composition of FA profiles. Cultured A. pallida that best mimicked wild anemones were obtained when using a regular light regime, Artemia metanauplii and 22 °C water temperature. Higher FA levels were obtained at a higher temperature and by providing nauplii to cultured anemones. The present study also indicated that A. pallida has the potential to recycle nutrients in marine aquacultures.     

小球藻固定化培养的初步研究

用海藻酸钙作固定化载体，初步探讨了海藻酸钠浓度、CaCl2浓度、胶球密度、胶球直径等固定化条件对小球藻（Chlorella vulgaris)生长的影响。确定了优化的固定化条件为：4＃针头、2％的海藻酸钠溶液和0．15mol/L的CaCl2溶液制备固定化小球藻，在含50mL培养液的150mL三角烧瓶内放置250个小球藻胶球时，其生长速度较高，生长周期较长。与游离的小球藻相比，固定化小球藻生长速率慢，但生长周期长。实验结果为微藻固定化技术的应用和发展提供了必要的实验数据和理论基础。     

Maturation and spawning performance of pond-reared Penaeus merguiensis in different combinations of temperature, light intensity and photoperiod

The combined effects of temperature (23 and 27 °C), light intensity (1100 and 2 lux or ≈ 21.5 and 0.04 μEinst m^?2 s respectively) and photoperiod (10 h light/14 h dark and 14 h light/10 h dark) on ovarian maturation and spawning performance of ablated pond‐reared Penaeus merguiensis were investigated in a 51‐day experiment. The results showed that temperature was the most influential factor, followed by light intensity, whereas the effect of photoperiod was minor. As the maturation process progressed, the effects of temperature and light intensity became stronger while that of photoperiod became less significant. Temperature significantly affected all the reproductive parameters assessed. Prawns in the 27 °C treatments outperformed those in the 23 °C treatments (P < 0.05). The effect of light intensity was found to have a significant effect (P < 0.05) only on the proportion of spawners (prawns that spawned) and spawning rate. More prawns spawned at a higher rate under dim light (2 lux) than under strong light (1100 lux). Photoperiod affected only the proportion of prawns reaching stage III of ovarian development (P < 0.05). There were interactions between temperature and light intensity affecting the proportion of prawns reaching stage III and, although not significantly, the proportion of spawners (P = 0.177), fecundity (P = 0.134) and survival (P = 0.061). Overall, it is recommended that a combination of 27 °C, 2 lux and 10 h light/14 h dark is suitable for the maturation of pond‐reared P. merguiensis. There were indications that temperature can be used to control the rate of ovarian maturation. Also, it is possible to increase light intensity up to 1100 lux in P. merguiensis hatcheries if prawns are ablated.     

Effects of dietary fish oil replacement by microalgae raw materials on growth performance,body composition and fatty acid profile of juvenile olive flounder,Paralichthys olivaceus

Replacing dietary fish oil with DHA‐rich microalgae Schizochytrium sp. and EPA‐rich microalgae Nannochloropsis sp. for olive flounder (Paralichthys olivaceus) was examined. Three experimental isonitrogenous and isolipidic diets with lipid source provided by 50% fish oil (F50S50), 50% (M50F25S25) and 100% microalgae raw material (M100) respectively were compared with a soybean oil (S100) diet as control. Triplicate groups of olive flounder juveniles (16.5 ± 0.91 g) were fed the experimental diets, and a group was fed the control diets for 8 weeks in a recirculation system. Results showed feed efficiency and growth performance were not significantly changed when fish oil (FO) was totally substituted by soybean oil (SO) or microalgae raw material (MRM). The whole‐body composition, lipid content of liver and muscle, and lipid composition of plasma were not significantly influenced by the total substitution of FO by MRM. The polyunsaturated fatty acids (PUFA) content of muscle and liver declined in fish fed S100 diet, whereas it was not significantly reduced in fish fed M50F25S25 and M100 diets. The total substitution of FO by MRM not only maintained the levels of arachidonic acid, EPA or DHA but also increased n‐3/n‐6 ratio. In conclusion, MRM as the sole lipid source is sufficient to obtain good feed efficiency, growth performance and human health value in olive flounder juveniles.     

不同浓度漂白粉处理对水体中小球藻和原生动物的影响

以小球藻为研究对象,利用小球藻比原生动物耐受氧化剂能力强的特点,往被原生动物污染的藻液中添加7组不同浓度的漂白粉,探讨漂白粉处理小球藻液的最适浓度.结果显示:在温度为25℃、光照为2 500 lx、盐度为26的条件下,以均匀泼洒全池后水体漂白粉浓度为15 mg/L时最利于小球藻生长,且能够有效杀除小球藻中的原生动物,藻细胞在2d内逐渐恢复,显微镜观察未发现原生动物,小球藻生长速度显著升高,达到了常规培养的藻细胞浓度.     

Effects of dietary phospholipid and highly unsaturated fatty acid on the gonadal development, tissue proximate composition, lipid class and fatty acid composition of precocious Chinese mitten crab, Eriocheir sinensis

Precocious puberty is a major constraint to the economical rearing Eriocheir sinensis farming. Although dietary phospholipid (PL) and highly unsaturated fatty acids (HUFA) reportedly enhanced ovarian development in normal adult E. sinensis , it had opposite effects of reducing precocity in juveniles . This study investigated the effects of dietary PL and HUFA on survival, gonadal development and biochemical composition of precocious E. sinensis . Two diets with PL and HUFA supplementation (diet A) and deficient (diet B) were formulated and fed to precocious E. sinensis . Although no significant differences were found on survival and gonadosomatic index of crabs fed both diets, crabs fed diet B had significantly higher hepatosomatic index and hepatopancrean lipid content than crabs fed diet A. The percentages, 14:0, 18:1n-9, 20:5n-3 and 22:6n-3, in hepatopancreas, muscle and gonads were positively correlated to the diets. Interestingly, the crabs fed diet B accumulated significantly higher 18:2n-6 in gonads and muscle than those fed diet A. Furthermore, substantially higher 20:4n-6 was detected in the gonad and muscle than in the diets. These results suggested that dietary PL and HUFA had limited effects on male gonad biochemical composition. Meanwhile, the precocious E. sinensis may be capable of negating the negative effects of HUFA deficiency by enhanced tissue 18:2n-6 accumulation and converting 18:2n-6 to 20:4n-6.     

光照对细胞融合藻Tetraselmis sp·－1混合培养的影响

对细胞融合技术获得的1株新型融合微藻(Tetraselmis sp.-1)进行摇瓶混合培养,并分析光照强度对该培养条件下融合微藻的影响.结果表明1) 在培养基中添加葡萄糖对融合微藻的生长有强烈的促进作用,融合微藻生长速率为0. 576 g/(L*d),是自养培养的7.38倍;2)在光照强度为3 000 lx混合培养时,葡萄糖消耗速率达最大值3 g/(L*d);3)在光照强度为2 000 lx混合培养时,藻细胞密度最大,为2.60 g/L,以葡萄糖计算的基质得率随光照强度的增加而显著下降;4)融合微藻叶绿素a含量在混合培养条件下,随光照强度的增大而增加;5) 在混合培养条件下,光照对NH4+的同化为正影响,融合微藻氮含量和CC/CN分别为5.68和6.06,均介于自养培养与异养培养之间.     

日粮脂肪水平对克氏原螯虾的生长、体组成及脂肪酸组成的影响

研究了日粮中脂肪水平对克氏原螯虾的生长、体组成及脂肪酸组成的影响。630尾初始重为(4.76±0.42)g克氏原螯虾随机分为六组(1~6组),每组3个重复,每个重复35尾,用六个脂肪水平(1.82%、3.84%、5.79%、7.89%、9.91%和11.95%)饲料饲养60 d后测定虾的生长指标、体组成和脂肪酸组成。结果表明,克氏原螯虾的适宜日粮脂肪水平为7.89%~9.91%。     

Effect of soy oil containing stearidonic acid on growth performance and fillet fatty acid composition of Atlantic salmon

The effects of stearidonic acid (SDA; 18:4n‐3) derived from SDA‐enhanced, genetically modified soybeans (Monsanto Company, St Louis, MO, USA) on growth performance and fatty acid (FA) composition of large Atlantic salmon (Salmo salar; 2.1 kg initial weight) were evaluated. There was a stepwise decrease in feed intake and subsequent weight gain of immature Atlantic salmon with increased replacement of fish oil by SDA soy oil from 0%, 50% to 100% added oil. SDA increased and n‐3 highly unsaturated FA (n‐3 HUFA; eicosapentaenoic acid + docosahexaenoic acid) decreased in the diet and corresponding fillet with increased SDA oil inclusion. Salmon with the same weight gain fed SDA oil compared with rapeseed oil at 50% fish oil replacement had similar n‐3 HUFA fillet levels indicating little or no increased synthesis of n‐3 HUFA from SDA for deposition in the fillet. However, elongation of dietary SDA to 20:4n‐3 for deposition in the fillet of SDA oil fed fish was indicated. The increased SDA and 20:4n‐3 in the fillet of Atlantic salmon fed SDA oil compared with rapeseed oil at 50% fish oil replacement may be more effective as precursors for EPA in humans than 18:3n‐3 which was in the fillet at similar levels.     

Effect of short- and long-term lipid enrichment on total lipids,lipid class and fatty acid composition in rotifers

Four emulsions differing in lipid class composition: triacylglycerols, ethyl esters, phospholipids and wax esters were used to enrich rotifers either through short-term (ST) enrichment (24 h) or through long-term (LT) enrichment (10 days). Higher lipid levels were obtained by using the ST enrichment method. This was particularly marked in the high triacylglycerol accumulation in rotifers enriched on the phospholipid-based emulsion. Ethyl esters were effectively assimilated and incorporated into triacylglycerol by rotifers in both the ST and LT techniques. A high docosaehexanoic/eicosapentaenoic acid (DHA/EPA) ratio was obtained in the LT technique using the ethyl ester-based emulsion. However, the other emulsion treatments gave higher or equal DHA/ EPA ratios using the ST technique. Absolute phospholipid levels were independent of both dietary lipid composition and enrichment method used, whereas triacylglycerol levels depended on these parameters. During starvation the level of phospholipid, in absolute terms, decreased slightly whereas the triacylglycerol fraction decreased considerably. Rotifers enriched on the wax ester-based emulsion using the LT technique exhibited higher levels of long-chain monoenes (i.e. 20:1 and 22:1 isomers) than when the ST technique was used. This suggests that hydrolysis of the wax esters and oxidation of the liberated fatty alcohols to fatty acids occurred when the LT technique was applied.     

太空搭载小球藻（Chlorella vulgaris）子代群体新品系的筛选、培养及其营养组成分析

本文以经过太空搭载返回地面后保存的小球藻（Chlorella vulgaris）藻种T0为实验材料,从提高小球藻生长速度和促进小球藻油脂富集两个方面考虑,对小球藻生长的环境因子和培养基成分进行探讨和研究;最终经过两次筛选获得速长-油脂高产的株系TY31.实验结果表明,小球藻在140 μmol·m-2·s-1光照强度、23℃培养温度、以3.75 mmol/L的NH2 CONH2为氮源、以0.12 mmol/L的K2HPO4为磷源的最佳培养条件下,细胞生长速度加快,生长期变长,蛋白、脂肪及脂肪酸含量增加.研究发现,以第一次筛选的小球藻藻株T9为出发株,采用改良的BG-11培养基进一步选育的速长-油脂高产株系TY31,其最终细胞密度增加11.06×106 mL-1,脂肪含量增加6.50％,脂肪酸含量增加3.76％,具有应用于生物能源研究的潜力,为海洋微藻的开发利用奠定了基础.