环境因子对星斑川鲽呼吸频率的影响

研究了温度、盐度与pH对星斑川鲽呼吸频率的影响。结果显示：在适宜温度范围星斑川鲽呼吸频率随温度的升高而加快,在4—26℃范围内,其呼吸频率V冉温度T基本呈线性关系：Vf=1．8168T＋27．23,R=0．9376;在盐度5—31范围内其呼吸频率变动幅度小,呼吸频率的改变量只有10次,分,为广盐性鱼类;高pH（10．15）和低pH（3．0）情况下,星斑川鲽的鳃盖张合大,鳃盖外缘外翘;30分钟后表现出不适应,上下窜动,而在pH=3．0中的鱼1小时50分钟后全部死亡,可见星斑川鲽耐酸性不如耐碱性。     

饥饿后再投喂对星斑川鲽生化组成以及能值的影响

采用饥饿不同时间后再恢复投喂相同时间的方法,在温度19±1℃、盐度32±1的条件下,对相同规格的星斑川鲽(26.02±0.30 g)鱼体和粪便的生化组成以及能值等相关指标的影响进行了研究.研究结果表明,饥饿后再投喂对星斑川鲽鱼体内水分、脂肪和灰分的含量影响显著,对鱼体内蛋白质含量无显著影响;对粪便脂肪和蛋白质含量影响显著,对粪便中灰分无显著影响;对鱼体能值影响显著,对粪便的能值无显著影响.研究还发现,饥饿处理时间越长,各相关指标变化越显著;随着恢复投喂的进行各相关指标逐渐恢复到对照组水平,饥饿处理时间越长,恢复到对照组水平所需要的时间越长.     

Optimum dietary protein to lipid ratio for Starry flounder (Platichthys stellatus)

An 8‐week feeding trial was conducted to evaluate the optimum dietary protein to lipid ratio (P/L) for Starry flounder Platichthys stellatus (30.7 ± 0.7 g initial weight). Nine fishmeal‐based diets with three protein levels (40%, 45% and 50%) and three lipid levels (8%, 11% and 14%) were fed to 30 fish in triplicate. Results showed that the growth performance was affected by dietary P/L ratio significantly, and the best weight gain rate, specific growth rate and feed conversion ratio were appeared at fish fed P45L14 and P50L11 diets. Apparent digestibility coefficient of protein was increased with increasing dietary lipid, but lipid digestibility was decreased by dietary lipid. Lipid deposition in tissues was increased with increasing dietary lipid at each protein level and was higher for the lower protein diets. In liver, the per cent of both eicosapentaenoic acid and docosahexaenoic acid were increased by dietary protein. High dietary protein level (50%) at high lipid level (14%) increased arachidonic acid significantly. Aspartate aminotransferase and alanine aminotransferase were affected significantly by dietary P/L ratios. High density lipoprotein cholesterol and total cholesterol of 45% protein groups were significantly higher than others. The study revealed that the optimum dietary protein to lipid ratio for starry flounder was P45L14 or P50L11, or P/E ratios were 25.49 and 27.70 mg protein kJ^?1 gross energy respectively.     

Effect of dietary lipid level on the growth performance,feed utilization,body composition and blood chemistry of juvenile starry flounder (Platichthys stellatus)

A study was conducted to determine the effect of dietary lipid level on the growth performance, feed utilization, body composition and blood chemistry of juvenile starry flounder. Five isonitrogenous diets with increasing dietary lipid levels (6%, 10%, 14%, 18% and 22% dry material) were each fed to triplicate groups of starry flounder (29.9 g) for 8 weeks. Weight gain (WG) and specific growth rate of fish fed the 6% lipid diet were significantly lower than the other groups, while there was no significant difference in fish fed the 10%, 14%, 18% and 22% lipid diets. Body lipid content increased with increasing dietary lipid levels. The moisture content of the whole body was negatively correlated to the dietary lipid level. The dietary lipid level also affected the lipid content of the dorsal muscle positively. Liver lipid content increased as the dietary lipid level increased from 6% to 14% and then decreased. With increasing dietary lipid level, the nitrogen retention achieved the highest value when the fish were fed the 14% lipid diet, but there were no significant differences with the 10% and 22% groups. The plasma total protein content first showed an increasing and then a decreasing trend with increasing dietary lipid level, and it was significantly higher in the 14% lipid group than other groups. Based on the WG response using the broken‐line model, the optimum dietary lipid level for juvenile starry flounder was estimated to be 10.62% in the experiment.     

Extraction of Fatty Acids and Phenolics from Mastocarpus stellatus Using Pressurized Green Solvents

Polyunsaturated fatty acids are well known for their protective properties in relation to different skin diseases. Although seaweeds possess a low lipid fraction, they could act as an alternative renewable source of polyunsaturated fatty acids whenever other valuable seaweed components are also valorized. In this study, a biorefinery process using Mastocarpus stellatus as a model seaweed was proposed. The process started with the supercritical carbon dioxide extraction of the lipid and phenolic fractions. The influence of pressure during extraction with pure supercritical CO₂ was studied while operating at a selected temperature and solvent flow rate. Kinetic data obtained during the ethanol-modified supercritical CO₂ extraction were fitted to the spline model. Sequential processing was proposed with (i) pure CO₂ to obtain a product with 30% PUFA content and ω-3:ω-6 ratio 1:1, (ii) ethanol-modified CO₂ to extract phenolics, and (iii) microwave-assisted subcritical water extraction operating under previously optimized conditions for the extraction of phenolics, carrageenan and protein fractions. The composition of the supercritical extracts showed potential for use in both dietary and topical applications in skin care products. The remaining solids are suitable for the extraction of other valuable fractions.     

井冈寒竹种群生物量结构初步研究

研究了井冈寒竹种群的生物量结构,结果表明:井冈寒竹种群的总生物量为1602.92g/m2,其中地上部分为956.39g/m2,占59.67%,地下部分为646.53g/m2,占40.33%。不同构件生物量结构为:秆605.02g/m2,叶209.68g/m2,枝141.69g/m2,鞭532.87g/m2,篼113.66g/m2;井冈寒竹种群中1～4龄级个体生物量的分配依次为:6.25%、26.49%、48.09%和19.17%;井冈寒竹种群中各构件单位生物量在不同年龄分株上的分配亦有差异,地上部分含量逐渐上升,地下部分含量逐渐下降;秆、枝、叶的平均含水率分别为46.05%、57.87%和60.10%,以秆最少,叶最多。     

星斑川鲽亲鱼生殖调控技术研究

通过星斑川鲽全人工育苗生产,研究了星斑川鲽在人工养殖条件下,对亲鱼培养促熟营养配方,温度及光照周期的调控技术,以及养殖培养管理技术等,分析了星斑川鲽亲鱼生殖调控技术思路。     

Creatine turnover in the starry flounder,Platichthys stellatus

Starry flounder (Platichthys stellatus) were cannulated and a bolus of 9 Ci¹⁴C-creatine in saline was injected into the caudal vein. The fish were sacrificed at intervals ranging from 1h to 36d after label injection. Creatine pool size (PCr+Cr) and creatinine (Crn) content in blood, muscle, gills and liver were analyzed and specific activities (SA) determined.Mean concentrations of PCr+Cr/Crn in PCA-extracts of muscle, gills, liver and blood of experimental fish (at rest) were 38.1/2.40, 4.1/0.25, 5.6/0.45 and 0.3/n.d. mol.g^–1 respectively.Within 10 min, plasma SA had decreased by approximately 90%. In white muscle, the rate of¹⁴C–Cr appearance as well as label disappearance was slow compared to gills and liver. In fish examined 36d postinjection, mean SA in muscle had decreased to 23% of maximum SA which occurred 24h after injection.¹⁴C–Cr was incorporated into the liver tissue at a very high rate, SA being two orders of magnitude higher in liver than in white muscle. Over the first 6d, retention of label was observed in liver; after 36d only 3% of the original label was detected.Creatine pool size (PCr+Cr) in white muscle decreased with food deprivation. In flounder sacrificed after 36d, PCr+Cr was only 52% that of fed control fish, suggesting that creatine or precursors for its biosynthesis are supplied with the diet.     

Rearing of flounder (Platichthys flesus) juveniles in semiextensive systems

A low-technology rearing system was implemented for rearing juvenile flounder for stock enhancement in a Danish fjord, the Limfjord. Each year during 1996–2002, between 13,000 and 153,000 juveniles were reared from the yolk-sac stage until metamorphosis in outdoor ponds relying on phyto- and zooplankton blooms as their main food source. In contrast to other similar systems, the blooms in this system are closely monitored and, to a certain extent, regulated. The zooplankton blooms consisted mainly of calanoid copepods, dominated by the species Temora longicornis and Centropages hamatus. Most juveniles produced (>99.5%) were normally pigmented with average yearly survival rates from hatch to metamorphosis varying from 7±9% to 48±18%, lowest in the first years of production.     

温度对星斑川鲽消化酶活性的影响

通过改变酶反应过程中的温度,分析了星斑川鲽蛋白酶、淀粉酶和脂肪酶的活性。结果表明:胃、肠和肝胰腺蛋白酶活性的最适温度为40,45,45℃;其蛋白酶活性大小顺序为胃肝胰腺肠。胃、肠和肝胰腺淀粉酶活性的最适温度为35,40,35℃;其淀粉酶活性大小顺序为肠肝胰腺胃。胃、肠和肝胰腺脂肪酶活性的最适温度为35,30,30℃;其脂肪酶活性大小顺序为肝胰腺肠胃。