凡纳滨对虾常见养殖模式下养殖后期浮游植物及理化因子的变化

对凡纳滨对虾几种常见养殖模式后期的浮游植物及理化因子进行了调查研究,结果表明,浮游植物的群落特征因养殖模式、养殖时间、不同的环境条件等原因变化很大,其群落组成由最少的11种到最多的28种不等;其优势种与次优势种中以蓝藻门、绿藻门、硅藻门为主,甲藻门、裸藻门偶有出现,主要优势种有小环藻、波吉卵囊藻、中肋骨条藻、颤藻、林氏藻、裸甲藻、胶球藻、小席藻、腔球藻等,浮游植物群落的生物多样性由高至低依次为高位池分级精养模式、海水土池粗养模式、低盐度养殖模式、咸淡水半精养模式、工厂化集约养殖模式、高位池集约养殖模式,多样性指数与优势度呈显著的负相关,而与均匀度呈显著的正相关。细胞密度485.9×104~35459.8×104L-1,在高密度精养模式中,浮游植物的密度与无机氮、硫化氢含量的变化在早期呈负相关,在后期则几乎同步增长;在低密度养殖模式中,浮游植物的密度与无机氮、硫化氢含量的变化始终呈负相关。各养殖模式pH值的变化与浮游植物的密度呈正相关。综合分析表明,高密度养殖宜采用高位池分级精养模式,低密度养殖宜采用海水土池粗养模式。     

2种养殖模式下凡纳滨对虾池塘水质理化因子的变化特征

2016年4月23日至7月12日对地膜精养及普通土池模式下凡纳滨对虾池塘水体的主要理化因子进行跟踪监测,研究不同养殖模式对水质变化的影响。结果表明,2种养殖模式下池塘水体的p H和DO均随养殖时间的延长逐渐下降,地膜池与普通土池相比p H无统计学意义(P>0.05),但30 d起地膜池DO含量高于土池(P<0.05);地膜池和土池的COD、氨氮、亚硝酸盐和磷酸盐的含量总体上均呈上升趋势,但土池亚硝酸盐含量在养殖后期(70~90 d)迅速下降。     

凡纳滨对虾高位池养殖系统的水质理化状况

对凡纳滨对虾高位养殖池水质环境状况进行了研究。结果表明，养殖期间虾池水体透明度前期较高，中后期较低；虾池pH变化在7．89-9．02之间，变化幅度较小。虾池水体悬浮物数量和CODMn随养殖时间延长而持续升高，变化范围分别为18．5—162．3mCL和3．52-14．58mg／L。虾池水体中营养盐各月份波动较大。无机氮的数量变化在0．206—1．621mg/L之间，含量逐渐升高，磷酸盐数量变化在0．009-0．067mg／L之间，含量逐渐下降。水环境中N、P比较高，平均为62．7。养殖水体中后期处于严重富营养化状态。     

凡纳滨对虾与点带石斑鱼的混养模式

对凡纳滨对虾(Litopenaeus vannamei)与点带石斑鱼(Epinephelus malabaricus)进行90 d的混养试验,研究点带石斑鱼混养密度、规格对凡纳滨对虾生长、成活率和产量的影响。结果表明,点带石斑鱼混养密度、规格均对凡纳滨对虾生长、成活率和平均产量的影响有统计学意义(P0.05)。在混养密度相同的条件下,混养小规格点带石斑鱼的凡纳滨对虾成活率比混养大规格点带石斑鱼提高15.1%~23.2%,平均产量比混养大规格点带石斑鱼提高19.0%~40.6%。随着点带石斑鱼混养密度增加,凡纳滨对虾成活率和平均产量呈下降趋势。小规格点带石斑鱼混养密度分别为0.4尾·m-2时,凡纳滨对虾成活率和平均产量最高,分别为66.25%%±7.24%、(1 181.0±101.8)kg,较单一养殖凡纳滨对虾成活率提高5.46%,平均产量提高16.2%;大规格点带石斑鱼混养密度为0.2尾·m-2时,凡纳滨对虾成活率和平均产量最高,分别为(52.04±6.11)%、(959.8±89.1)kg,但较单一养殖凡纳滨对虾成活率下降8.75%,平均产量下降5.88%     

凡纳滨对虾高位池养殖系统的水质理化状况

对凡纳滨对虾高位养殖池水质环境状况进行了研究。结果表明,养殖期间虾池水体透明度前期较高,中后期较低;虾池pH变化在7.89~9.02之间,变化幅度较小。虾池水体悬浮物数量和CODMn随养殖时间延长而持续升高,变化范围分别为18.5~162.3 mg/L和3.52~14.58 mg/L。虾池水体中营养盐各月份波动较大,无机氮的数量变化在0.206~1.621 mg/L之间,含量逐渐升高,磷酸盐数量变化在0.009~0.067 mg/L之间,含量逐渐下降。水环境中N、P比较高,平均为62.7。养殖水体中后期处于严重富营养化状态。     

光合细菌对养殖水质及凡纳滨对虾抗病力的影响

在凡纳滨对虾养殖环境中人工引入不同浓度的光合细菌,监测氨氮、亚硝酸氮、化学需氧量的变化,15d后测定凡纳滨对虾的AKP、POD、PO、SOD、抗菌、溶菌活力,以及不同光合细菌浓度下凡纳滨对虾的成活率与体重增长率,研究光合细菌对水质和凡纳滨对虾抗病力的影响。结果表明,引入光合细菌可显著降低水体化学需氧量、氨氮含量,并抑制亚硝酸盐氮的产生,提高凡纳滨对虾的抗病力。当光合细菌投放浓度为3×103/mL时,水体中化学需氧量、氨态氮、亚硝酸盐氮含量的均值分别比对照组降低31.59%、43.42%、52.20%,差异显著(P<0.05);对虾的AKP、POD、PO、SOD、抗菌、溶菌活力分别比照组提高31.92%、72.29%、55.56%、31.61%、39.07%、69.51%,差异显著(P<0.05);成活率,体重增长率分别比对照组提高18.67%、34.03%,差异显著(P<0.05)。     

凡纳滨对虾和斑节对虾对WSSV敏感性的比较

用6.0×104拷贝、1.2×104拷贝和6.0×103拷贝3种剂量白斑综合症病毒(WSSV)对凡纳滨对虾和斑节对虾进行人工注射感染,比较了两种对虾对WSSV敏感性的差异。结果表明,凡纳滨对虾死亡时间随病毒剂量降低而延长,斑节对虾死亡时间没有明显差异;随病毒剂量的降低,凡纳滨对虾人工注射感染后病毒复制高峰时间显著延长,斑节对虾感染后病毒复制高峰时间相同,WSSV在凡纳滨对虾体内比在斑节对虾体内复制慢。对虾携带WSSV数量最低为3.3×107拷贝.g-1,最高为4.3×108拷贝.g-1。凡纳滨对虾比斑节对虾对WSSV的抵抗性更强。     

两个凡纳滨对虾亲本群体的RAPD研究

采用Operon公司的 16个引物对两批凡纳滨对虾亲虾的基因组DNA多态性进行了检测 ,结果表明 ,第一个亲本群体对 16个引物共检测到 78个位点 ,其中多态位点数为 4 8个 ,占 6 1.5 4% ;第二个亲本群体共获得 97个位点 ,其中多态位点数为 4 9个 ,占 5 0 .5 2 %。单个引物获得的标记数为 1～ 8个。第一个亲本群体个体间的平均遗传距离为 0 .196 0± 0 .0 392 ,第二个亲本群体个体间的平均遗传距离为 0 .0 92 2± 0 .0 189。两个亲本群体间的多态位点比例为 6 6 .98% ,遗传距离为0 345 5± 0 .0 795。在OPF 0 9、OPV 19、OPZ 113个引物的扩增结果中 ,发现两个亲本群体有明显差异。     

凡纳滨对虾不同生长阶段食物组成结构的研究

利用稳定同位素碳比率δ13C作为天然示踪物,对高位养殖池生态系统中人工饲料和天然饵料提供的能源物质对养殖凡纳滨对虾生长的贡献比率进行研究。结果表明:虾体的δ13C值受食物δ13C值的影响,由于其摄食饵料的δ13C值逐渐减小,虾体的δ13C值也逐渐降低,逐渐接近于最后人工饲料的δ13C值,试验虾体的δ13C值由养殖开始时的-19.52‰±0.09‰变为实验结束时的-21.74‰±0.17‰;对虾的食性在10d左右时发生转变,34d左右时人工饲料和浮游动物对虾体的能量贡献基本相同,养殖结束时对虾生长能量的97.29%±0.98%来源于人工饲料。     

珠海地区凡纳滨对虾淡水养殖池浮游植物群落的演替

对珠海凡纳滨对虾淡水养殖池塘浮游植物及其理化因子进行了调查和分析,结果表明:调查中共检出浮游植物143种,优势种主要有林氏藻、螺旋鱼腥藻、小颤藻、微囊藻和点状平裂藻等,物种多样性指数在0.24~2.77之间,优势度与多样性指数呈显著的负相关,相关系数r=-0.984;而均匀度与多样性指数呈显著的正相关,相关系数r=0.967,养殖后期优势度不高,浮游植物的密度及化学因子的浓度到后期都有所上升,藻类密度的剧烈变化会引起氨氮和硫化氢含量的变化;藻类密度的波动滞后于无机氮的波动,群落演替具有突发性、时间短、速度快等特点。     

贮藏时间和加热温度对凡纳滨对虾虾仁ATP关联化合物及品质的影响

【目的】研究贮藏时间和加热温度对凡纳滨对虾(Litopenaeus vannamei)虾仁三磷酸腺苷(ATP)关联化合物及虾仁品质的影响。【方法】利用高效液相色谱法分析凡纳滨对虾中6种ATP关联化合物,通过比较不同贮藏时间的凡纳滨对虾虾仁在加热过程中的ATP关联化合物,分析加热前后虾仁的感官品质,以及鱼虾类鲜度指标K值、G值、P值的变化。【结果与结论】随贮藏时间的增加,ATP、二磷酸腺苷(ADP)、腺苷酸(AMP)含量呈下降趋势,肌苷酸(IMP)先上升后下降,次黄嘌呤(HX)和肌苷(HXR)上升;随着加热温度的增加,ATP和ADP下降,AMP增长,IMP、HX、HXR先增加后降低。贮藏2 d后的生虾和贮藏3 d后再加热的虾仁均将达到最大感官可接受上限。随着贮藏时间的增加,加热前后K值、G值和P值线性增加,但生虾的G值与鲜度的相关性较差,不适宜作为鲜度指标,K值和P值可作为生虾的鲜度指标。加热后的K值、G值、P值与贮藏时间、感官质量评定值(QI值)的线性回归方程的决定系数较好,表明K值、G值、P值可以用来表征熟虾的品质。     

The Effects of Rapid Temperature Changes on HK,PK and HSP70 of Litopenaeus vannamei in Different Seasons

Activities of hexokinase(HK),pyruvate kinase(PK) and levels of HSP70 were measured to evaluate the response of Litopenaeus vannamei to rapid temperature changes under controlled laboratory conditions.Shrimps were subjected to a quick temperature change from 27℃ to 17℃ for the summer case(Cold temperature treatment),or from 17℃ to 27℃ for the winter case(Warm temperature treatment).After 0.5,1,3,6,12,24,48,and 72 h of exposure time,shrimps were sampled and prepared for further analysis.The results showed that the effect of acute temperature changes on activities of HK was significant.Patterns of variations of the two glycolytic enzymes suggested that enzymes in the glycolysis cycle could adjust their activities to meet the acute temperature change.The HSP70 level increased in both cold and warm temperature treatments,suggesting that the rapid temperature changes activated the process of body's self-protection.But the difference in expression peak of HSP70 might be related to the different body size and the higher thermal sensitivity to temperature increase than to temperature decrease of L.vannamei.     

Comparison of the respiratory metabolism of juvenile Litopenaeus vannamei cultured in seawater and freshwater

Litopenaeus vannamei, a euryhaline species, can be cultured at a wide range of salinities. The emergence of freshwater pond-culture of L. vannamei is an important prelude to the continued development of shrimp culture in China. In this study, we compared the respiratory metabolism of juvenile L. vannamei cultured in freshwater and saltwater by measuring their oxygen consumption rate (OCR), ammonium-type nitrogen excretion rate (AER) and pyruvate kinase (PK) and lactate dehydrogenase (LDH) activities at different molting stages in order to physiecologically characterize juvenile L. vannamei under freshwater conditions. The results showed that OCR was significantly higher in saltwater than in freshwater at all stages of molting cycle. However, variation of OCR among molting stages in saltwater was similar with that in freshwater, and the highest OCR was observed at post-molting stage. At all stages of molting cycle, AER was significantly higher in freshwater than in saltwater, and the highest was observed at post-molting stage. The activity of PK was significantly higher in saltwater than in freshwater. Conversely, the activity of LDH was higher in freshwater than in saltwater in general. Significant variation of PK and LDH activities in molting cycle was observed in saltwater and freshwater. The results indicated that aerobic metabolism of juvenile L. vannamei was more active in saltwater than in freshwater; while its protein metabolism was more active in freshwater than in saltwater.     

Optimal content and ratio of lysine to arginine in the diet of Pacific white shrimp, Litopenaeus vannamei

The optimal quantity of dietary lysine (Lys) and arginine (Arg), and the optimal ratio of dietary Lys to Arg for Pacific white shrimp Litopenaeus vannamei were investigated. Coated Lys and Arg were added to a basal diet (37.99% crude protein and 7.28% crude lipid) to provide graded levels of Lys and Arg. The experimental diets contained three Lys levels (2.51%, 2.11%, and 1.70% of total diet), and three Arg levels (1.41%, 1.80%, and 2.21% of total diet) and all combinations of these levels were tested. Pacific white shrimp, with a mean weight of 3.62±0.1 g, were randomly distributed in 36 fiberglass tanks with 30 shrimp per tank and reared on the experimental diets for 50 days. After the feeding trial, the growth performance, survival, feed conversion rate (FCR), body composition and protease and lipase activities in the hepatopancreases of the experimental shrimps were determined. The results show that weight gain (WG), specific growth rate (SGR), FCR, body protein, body Lys and Arg content were significantly affected by dietary Lys and Arg (P <0.05) and improved when dietary Lys and Arg levels were 2.11% ～ 2.51% and 1.80%～2.21%, respectively. Protease and lipase activities in the hepatopancreases of the shrimps appeared higher when dietary Lys and Arg quantities were 2.11% ～2.51% and 1.80%～2.21%, although the difference was not statistically significant (P >0.05). Therefore, according to our results, the optimal Lys and Arg quantities in the diet of Pacific white shrimp, L. vannamei, were considered to be 2.11%–2.51% and 1.80%–2.21%, respectively, and the optimal ratio to be 1:0.88–1:1.05.     

Effect of dietary potassium on growth,nitrogen metabolism,osmoregulation and immunity of pacific white shrimp (Litopenaeus vannamei) reared in low salinity seawater

An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physiological acclimation of Pacific white shrimp(Litopenaeus vannamei) reared in diluted seawater(salinity 4). Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17+ g potassium K per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets(P0.05). The shrimps fed the diets containing 0.96-1.48 g K+ per 100 g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na+ and Cl- were significantly lower than those of the control(P0.05), but a reverse trend was observed for their gill Na+/K+-ATPase. Moreover, the shrimps fed with 1.48 g K+ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control(P0.05). The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K+ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.     

Effect of copper on the growth of shrimps Litopenaeus vannamei: water parameters and copper budget in a recirculating system

Shrimps( Litopenaeus vannamei) were intensively cultured in a recirculating aquaculture system for 98 days to investigate effects of 0.3 mg/L Cu on its performance, Cu budget, and Cu distribution. Shrimps in Cu-treated systems had greater mean final weight(11.10 vs 10.50 g), body length(107.23 vs 106.42 mm), survival rate(67.80% vs 66.40%), and yield(6.42 vs 5.99 kg/m 3), and lower feed conversion ratio(1.20 vs 1.29) than those in control systems but the differences were not significant. Vibrio numbers remained stable(10 4 –10 6 colony forming units/mL) in the rearing tanks of both control and treated systems. Total ammonium-N, nitrite-N, nitrate-N, pH, chemical oxygen demand, 5-day carbonaceous biochemical oxygen demand, and total suspended solids were similar in controls and treatments. Dissolved Cu concentration in the treated systems decreased from 0.284 to 0.089 mg/L while in the control systems it increased from 0.006 2 to 0.018 mg/L. The main sources of Cu in the treated systems were the artificially added component(75.7% of total input), shrimp feed(21.0%), water(2.06%), and shrimp biomass(1.22%). The major outputs of Cu occurred via the mechanical filter(41.7%), water renewal(15.6%), and draining of the sediment trap(15.1%). The foam fractionator removed only 0.69% of total Cu input. Harvested shrimp biomass accounted for 11.68% of Cu input. The Cu concentration of shrimps in the Cu-treated systems(30.70 mg/kg wet weight) was significantly higher than that in control systems(22.02 mg/kg). Both were below the maximum permissible concentration(50 mg/kg) for Cu in seafood for human consumption in China. Therefore, recirculating systems can be used for commercial on-growing of Litopenaeus vannamei without loss of shrimp quality, even in water polluted by 0.30 mg/L Cu. The mechanical filter is the main route for Cu removal.