Numerical Simulation of Dynamic Response of A Net Cage for Flatfish in Waves

A numerical model of flatfish cage is built based on the lumped mass method and the principle of rigid body kinematics. To validate the numerical model, a series of physical model tests are conducted in the wave flume. The numerical results correspond well with the data sets from physical model test. The effect of weight of bottom frame, height of fish net and net shape on motion responses of fish cage and tension force on mooring lines is then analyzed. The results indicate that the vertical displacements of float collar and bottom frame decrease with the increase in the weight of bottom frame; the maximum tension force on mooring lines increases with the increasing weight of bottom frame. The inclination angles of float collar and bottom frame decrease with the increasing net height; the maximum tension force increases obviously with the increase of net height.

Dynamic Analysis of Hydrodynamic Behavior of A Flatfish Cage System Under Wave Conditions

This paper presents a simulation model based on the finite element method. The method is used to analyze the motion response and mooring line tension of the flatfish cage system in waves. The cage system consists of top frames, netting, mooring lines, bottom frames, and floats. A series of scaled physical model tests in regular waves are conducted to verify the numerical model. The comparison results show that the simulated and the experimental results agree well under the wave conditions, and the maximum pitch of the bottom frame with two orientations is about 12o. The motion process of the whole cage system in the wave can be described with the computer visualized technology. Then, the mooring line tensions and the motion of the bottom frame with three kinds of weight are calculated under different wave conditions. According to the numerical results, the differences in mooring line tensions of flatfish cages with three weight modes are indistinct. The maximum pitch of the bottom frame decreases with the increase of the bottom weight.

Morphological study of the asymmetrical buccal cavity of the flatfish common solea(Solea solea) and its relation to the type of feeding

Objective:To investigate the surface architecture of the asymmetrical buccal cavity of Solea solea which are considered one of the most important predators in benthic communities.Methods:Adult Solea solea were obtained from Mediterranean Sea near Damielta.The heads were removed and processed for scanning electron microscopy.Its buccal cavity is asymmetrical and divided into roof and floor and the tongue for histological studies.Results:The buccal cavity roof is formed from upper jaw,velum and the palate.The upper jaw has several wing like processes with teeth arranged in several rows which may help in cutting and pushing the food to the entrance of the digestive canal while the floor is formed from the lower jaw and the tongue.The tongue is divided into apex,body and root.There is a gradual decrease of goblet cells in the tongue from anterior to posterior.These goblet cells function in protection of the epithelium.CoDctusions:Teeth in the floor of the buccal cavity and taste buds can be considered adaptive changes of the oral cavity related to the feeding habits and was a source to identify new and better methods of nutrition in aquaculture of Solea solea.

Production and Purification of Antioxidant Peptides from Flatfish Skin Protein Hydrolysates

Antioxidant peptides of flatfish skin protein hydrolyzed by four enzymes(Papain, Pepsin, Trypsin and Neutrase, respectively)were investigated. The Trypsin hydrolysate obtained by hydrolysis exhibited the highest 1,1-dipheny-l-2-picrylhydrazyl(DPPH)radical scavenging activity(DRSA)compared with other hydrolysates. Response surface method ology(RSM), based on Box-Behnken design, was used to study the influence of hydrolysis conditions on the DRSA. The optimal hydrolysis conditions were as follows: p H 7.38, temperature 48.2℃ and enzyme/substrate(E/S)ratio 2 840 U/g. Under these conditions, the maximum DRSA was(22.85 ± 0.57)%,. The experimental values agreed with the value(23.09%,)predicted by the model within a 95%, confidence interval. By using gel filtration chromatography and reversed-phase high performance liquid chromatography(RP-HPLC), antioxidant peptide(D2-P)was isolated from flatfish skin protein hydrolysates(FSPH)and could exhibit a(54.28 ± 1.37)%, scavenging activity on DPPH radical at the concentration of 5 mg/m L. This is the first report of a scientific basis for the preparation of antioxidant peptides from flatfish skin. The results suggested that the antioxidant peptides can be exploited into functional foods or used as a novel source of nutraceuticals.

Comparative Analysis of Mitochondrial Control Region Sequence from Three Flatfish Species(Pleuronectidae)

The 5’-end of the mitochondrial control region sequences of three flatfishes (Pleuronectiformes: Pleuronectidae) were amplified and sequenced. These sequences were compared with those of other three Pleuronectids species retrieved from GenBank. A phylogenetic tree was constructed based on the partial control region sequences. The results of phyloge- netic analysis are consistent with those of conventional systematics. Compared to previous studies, the structure of the 5’-end of mitochondrial control region was analyzed. The terminal associated sequence motif and its complementary motif were i- dentified at the 5’-end of the sequences. A conserved sequence block, named as CM5’d, was identified in the 5’-end of con- trol region sequences in all Pleuronectids. Another central conserved sequence block, named as CSB-F, was detected in the central conserved blocks.

Investigation of hydrolysis conditions and properties on protein hydrolysates from flatfish skin

Response surface method （RSM）, based on Box-Behnken design, was used to optimize the enzymatic hydrolysis conditions of flatfish skin protein hydrolysates （FSPH）. Among the tested proteases, the combination of nutrase and trypsin was selected. The optimal hydrolysis conditions were as follows： pH 7.3, temperature 51.8℃, and the enzyme/substrate （E/S） ratio 2.5; under these conditions, the maximum peptide yield （PY） was 69.41 =1：0.43%. The physiochemical analysis showed that the amino acids （His, Asp and Glu） of FSPH accounted for 18.15%, and FSPH was a mixture of polypeptides mostly distributed among 900-2000 Da. FSPH could exhibit a 93% chelating effect on ferrous ion at a concentration of 400 gg/mL, and also a notable reducing power. This study showed bioprocess for the production of FSPH for the first time, which had a good potential for valuable ingredients in the food, cosmetic and medicine industries.

Molecular identification,expression pattern,and in-vitro bioactivity analysis of insulin-like growth factor 2 in olive flounder Paralichthys olivaceus

Insulin-like growth factors(IGFs)are key regulators of development and growth.Here,we characterized the igf2 gene from olive flounder(Paralichthys olivaceus)and determined its temporal and spatial expression.We set up an in-vitro protein expression system in eukaryotic human embryonic kidney(HEK293 T)cells and explored its effects on cell proliferation.The flounder igf2 cDNA contained a 648-bp open reading frame(ORF)encoding a protein of 215 amino acids(aa),which spanned the complete signal peptide(47 aa),mature peptide(70 aa),and E domain(98 aa).In adult flounder,igf2 mRNA was detected in all selected tissues.In early development,igf2 mRNA was detected throughout development from unfertilized eggs to hatching-stage embryos.In-situ hybridization analysis indicated that igf2 mRNA was specially expressed in the brain region,floor plate,hypochord,otic vesicle,and pectoral fin during embryogenesis.Western blotting analysis indicated that the soluble recombinant flounder IGF2 protein was successfully produced through eukaryotic expression in HEK293T cells.In addition,the recombinant IGF2 protein significantly promoted the proliferation of human cervical carcinoma(HeLa)and HEK293T cells.These results provide new information about the structural and functional conservation,expression patterns,and biological activity of the igf2 in teleosts.

海水源热泵在养殖水体升温与废水余热回收中的应用效果

该文开展了利用鲆鲽鱼类养殖废水作热源、为养殖用水升温的海水源热泵设备试验研究。探讨了养殖废水温度和流量对热泵的制热性能、养殖用水升温和废水余热的回收效果的影响。结果表明，养殖废水温度和流量愈高，热泵的制热性能改善愈明显，当废水温度为8．0～9．0℃、流量为200-700L／h时，热泵的制热性能系数（coefficientofperformance，COP）为2．61～3．85，废水温度升至10．5～14．6℃时，在上述流量范围内，热泵的COP值达到3．19～5．12；另外，养殖废水温度愈高或流量愈低，海水源热泵对养殖用水的升温效果愈好。当养殖废水温度低于10℃时，将流量控制在400L／h以下，海水源热泵可将7℃的养殖用水的温度提升至10．0～12．8℃，如果利用10．5～14．6℃的养殖废水作热源，流量达到700L／h时，海水源热泵能将养殖用水的温度由7℃升至10．4～13．4℃，利用IO℃以上的养殖废水作热源时，废水的最大降温幅度达9．2℃；此外，对比分析发现，利用10．5～14．6℃的养殖废水作热源时，海水源热泵对养殖用水的升温费用比燃煤（油、气）锅炉和电加热分别降低0．36、2．91、5．86和5．68元／t，每年比燃煤锅炉减排二氧化碳2．7～7．3t。

8种鲆鲽鱼种间遗传距离与杂交亲和性的相关性分析

2005-2008年,先后进行了褐牙鲆♀×夏牙鲆♂、褐牙鲆♀×石鲽♂、褐牙鲆♀×条斑星鲽♂、褐牙鲆♀×大菱鲆♂、大菱鲆♀×条斑星鲽♂的正反交试验,并收集了文献报道的研究资料,包括条斑星鲽×圆斑星鲽、石鲽×星斑川鲽、夏牙鲆×漠斑牙鲆及褐牙鲆×圆斑星鲽的正反交试验结果,对所涉及的8种鲆鲽鱼远缘杂交亲和性进行分析。根据Russell对杂交亲和性的定义,正反交均可行,杂交适合度为1;正反交单向可行,杂交适合度为0.5,正反交均不可行,杂交适合度为0。同时,根据这8种鲆鲽鱼的16S rDNA和COⅠ基因部分序列的差异,估算其种间遗传距离。对8种鲆鲽鱼的种间遗传距离和杂交适合度作相关性分析,二者呈线性负相关(R2=0.81,P<0.01),即杂交的亲和性随种间遗传距离增大而降低。研究表明,鲆鲽鱼的杂交亲和性与其遗传分化程度具有相关性,可以通过种间遗传距离对鲆鲽鱼远缘杂交的亲和性进行预测。

我国鲆鲽类循环水养殖系统的研制和运行现状

全封闭式海水循环养殖系统,是当前国际上先进养殖模式的代表,也是未来养殖产业发展的重要方向,备受世界关注。我国最早走上工厂化养殖道路的海水鱼类是鲆鲽类,现正由开放式向封闭式循环水养殖方向迈进,目前各项技术与工艺已经取得了长足进步。但是,根据对国内循环水系统装备的研制及其运行情况的跟踪调查,发现循环水处理的核心部分存在着稳定性、可靠性、经济性等问题急待研究解决。本文在分析循环系统主要配套装备和工艺参数的基础上,结合几家典型养殖企业的运行特点进行了分类剖析,针对现有装备和系统中发现的几个关键问题,提出了改进、提高的对策,可为今后鲆鲽类全循环养殖系统的升级、定型和走向国产化提供借鉴。

南极磷虾粉作为鲽形目鱼饲料蛋白源的营养价值评价

分析商品南极磷虾粉、自制酶解磷虾粉的主要营养成分(氨基酸和脂肪酸)组成,同时采用生化方法比较了5种鲽形目鱼肉蛋白的氨基酸组成。以5种鲽形目鱼肉蛋白为参比蛋白,利用必需氨基酸指数、氨基酸比值系数分和关联度分析法评价南极磷虾粉作为鲽形目鱼饲料蛋白源的营养价值,同时对2种磷虾粉的氟含量进行了分析。结果显示,鲽形目鱼肉(干样)中含有16种常见氨基酸,其中,7种为人体必需氨基酸,4种为呈味氨基酸(总量分别为28.52%–38.03%、25.26%–33.56%);5种鲽形目鱼氨基酸组成均符合FAO/WHO的理想模式。南极磷虾粉和酶解磷虾粉的粗蛋白分别为60.84%和68.60%,粗脂肪分别为12.08%和10.79%,达到了规定鱼粉的一级品甚至特级品的指标。酶解处理后蛋白含量显著升高(P<0.05),脂肪含量显著下降(P<0.05),灰分含量无差异(P>0.05)。从必需氨基酸指数(EAAI)来看,EAAI均大于0.95,磷虾粉的必需氨基酸与鲽形目鱼的必需氨基酸拟合度较高。从氨基酸比值系数分(SRC)和关联度分析法来看,2种磷虾粉对于鲽形目鱼的必需氨基酸平衡性较好,相关系数与鱼粉相差不大。氟含量方面,酶解后磷虾粉的氟含量[(331.21±6.70)mg/kg]显著降低(P<0.05),低于欧盟标准(350 mg/kg)。综合来看,2种磷虾粉氨基酸平衡性较好、营养价值较高,是优质蛋白源。

基于有限元方法对鲆鲽网箱耐流特性的数值模拟

鲆鲽网箱结构在海中受到水流的冲击作用会发生运动与变形,针对鲆鲽鱼特有的栖底习性,为确保网底结构的稳定有必要对其进行动力分析。为此利用有限元方法建立了流场中网箱受力和变形的数学计算模型,运用该数学模型对底框中加有支撑管结构并装配方形网目网衣的鲆鲽网箱整体位移进行了数值模拟。数值模拟结果表明,网箱的网衣部分在水流作用下形态变化比较大,网底的水平位移与垂直位移随流速的增加而增大,而网箱的底框架在不同流速条件下均能保持在水平位置,且未发生明显的倾斜。由此可见,此类鲆鲽网箱具有较好的耐流性能。

鲆鲽类白化机理的研究进展

鲆鲽类体色白化 ,在苗种生产过程中常见。很多学者对其进行过研究 ,然而关于白化的机理仍然不清楚。本文就近年来国内外有关鲆鲽类白化机理的研究从营养、遗传、环境。

褐牙鲆陆海接力养殖试验

试验对褐牙鲆(Paralichthys olivaceus)"陆海接力"养殖模式的可行性、养殖操作技术进行了研究。在山东荣成爱莲湾海域,分别于2008年和2009年5月,当海区水温上升至12.0℃以上时,将陆基工厂化培育的适宜规格苗种转运到海上,利用自行研制的方形钢结构鲆鲽类平底网箱养成褐牙鲆商品鱼。其中,2009年养殖平均体质量为59.3,136.0和202.0 g的褐牙鲆各1箱,经过174 d的养殖,平均体质量分别达到614.0,885.3和1 030.0 g,转运成活率100%,网箱养殖成活率分别为93.3%,87.5%和93.3%。结果表明,方形钢结构鲆鲽类平底网箱适合鲆鲽鱼类养殖,"陆海接力"模式养殖的褐牙鲆生长快、养殖周期短、成本低,而且该模式操作简单、节约能源。

自净式工业化养鱼水质及净化能力的研究

通过测定水中的总氨、亚硝酸氮、硝酸氮、活性磷和CODMn,研究了自净式养殖槽中生物膜熟化过程和生物膜的性能,以及在自净槽中进行了牙鲆Paralichthysolivaceus不同养殖密度下水质的变化和自净槽净化能力的实验。结果表明,自净式养殖槽中净化床的氨去除速率为46 0g/(m3·d)。养殖密度在2 30kg/m2(与工厂化生产养殖密度相近)以下时,循环水可以在5d内保持良好水质。

不同规格鲆鲽类的生化组成及营养价值比较

分析了不同规格鲆鲽类的生化组成并进行了营养价值研究和安全性评价。结果表明,不同规格的鲆鲽类鱼肉氨基酸都符合FAO/WHO公布的氨基酸理想模式:EAA/TAA含量在40%左右、EAA/NEAA在60%以上,重金属含量都符合国内外相关标准,所以鲆鲽类蛋白质都属于理想安全的优质蛋白质。不同规格鲆鲽类的FAA/TAA的比例都相近,而1～2kg的鲆鲽类的必需氨基酸、非必需氨基酸、鲜味氨基酸含量普遍高于0.5kg的大菱鲆。

鲆鲽类循环水养殖系统中病原菌的分布及杀除工艺

以半滑舌鳎皮肤溃疡病的致病菌灿烂弧菌Vibrio splendidus和哈维氏弧菌Vibrio harveyi为指示菌,研究了循环水养殖系统各环节中细菌分布和消除工艺。结果表明,不健康的苗种携带病原菌进入养殖系统后,可分布在残饵、池壁污物、养殖工具及循环水各处理环节。而弧形筛过滤、曝气池气升、紫外线消毒是循环水养殖系统消除细菌的三大环节。用5×10-6mol/L的KMnO4溶液浸泡工具2h,对细菌的杀灭率达到100%;用25×10-6mol/L的KMnO4溶液擦拭养殖池壁污物1.5min后,细菌杀灭率高于90%;用100×10-6mol/L浓度的H2O2溶液对养殖舌鳎病鱼进行药浴消毒处理10min,对体表细菌的杀灭率达到了94.49%。对鲆鲽鱼类循环水养殖系统中细菌的分布和消除效果进行了系统研究,研究结果可为建立循环水健康养殖工艺提供理论数据和参考。

促进鲆鲽类养殖产业朝循环经济方向持续健康发展——基于鲆鲽类主产区调研的战略思考

根据对主产区26个县的132户养殖单位的调查结果,按照循环经济原则,对我国鲆鲽类养殖产业的发展模式作出了初步判断,总结了现已存在的几种循环经济模式,剖析了发展鲆鲽类产业循环经济的5个主要障碍因素,阐述了循环经济发展中需要避免的三大误区,并提出了我国鲆鲽类产业从线性经济向循环经济转化的5个战略对策。

酶法制取比目鱼皮胶原蛋白寡肽

选用比目鱼皮作为一种新型的胶原蛋白资源,首先对其进行预处理,然后用2709碱性蛋白酶水解。利用单因素试验和响应面分析优化2709碱性蛋白酶水解比目鱼皮的最佳工艺条件为:pH10;底物质量浓度70g/L;温度55℃;加酶量4%;水解2h;最大水解度为22.36%。然后对水解产物进行后处理,得到了一套完整的生产鱼皮胶原蛋白寡肽的工艺。用飞行时间质谱仪测定所得水解产物的分子质量分布范围,结果表明其分子质量主要集中在0.6kDa～1.8kDa之间。

一种联排升降式鲆鲽鱼类网箱系统的构建与研究

根据鲆鲽鱼类特别适宜于在浅海沙质海床上底栖的生活习性,研制了一种HDPE联排升降式鲆鲽鱼类专用养殖网箱,其特点是既能沉入水底为鲆鲽鱼类营造一种近于海底的生态环境,又能抵御强风暴袭击和躲避赤潮灾害,并且升降操作简便,可多个箱体联排升降。经在海上实物网箱的重复升降试验,结果表明,联排升降式试验网箱的平均沉降时间为11.67 min,平均上浮时间为11.83 min,显示出了稳定快捷可靠的升降性能,是一种适合鲆鲽鱼类养殖的新型网箱。