基于PIV技术的圆形循环水养殖池流场

为研究进水管的设置距离和角度对双管进水式圆形循环水养殖池水动力特性的影响,该研究通过模型试验的方法,利用粒子图像测速技术（Particle Image Velocimetry,PIV）测量了不同进水管设置方式下养殖池内的流场。试验设计了3组进水管距池壁距离（进水管与池壁的最近距离,即进水管设置距离d）,每组距离工况下设计了8组进水角度（出水方向与养殖池切线形成的锐角,即进水管设置角度α）。利用PIV技术测量了不同工况下距离池底1 cm水层的流场,从水动力特征量（平均流速vavg和速度均匀系数U）分析进水管设置方式对养殖池水动力特性的影响。试验结果表明进水管设置方式明显影响养殖池的水动力特性：d=0时,随着α的增加,平均流速整体呈现先增大后下降的规律,在α=45°时取得最大值,但流场均匀系数随角度的增加而逐渐增加;d=1/4 r（r为养殖池半径）时,随着α的增加,平均流速和流场均匀系数都先缓慢增加然后再下降,分别在α=40°和30°时取得最大值;d=1/2 r时,随着α的增加,平均流速和流场均匀系数整体都呈现逐渐下降的趋势。综合比较24个试验工况的平均流速vavg和速度均匀系数U,建议将进水管设置为d=1/4 r,α=30°～40°,以期使养殖池内水动力特征有利于固体颗粒物的运动汇集,提升养殖池的集排污能力。本文研究成果可以为工厂化循环水圆形养殖池进水管设置方式提供参考。     

The impacts of aquaculture development on food security: lessons from Bangladesh

Fish contribute a significant amount of animal protein to the diets of people in Bangladesh, about 63% of which comes from aquatic animals. In Bangladesh, fish is mainly derived from two sources: capture and culture. Aquaculture has shown tremendous growth in the last two decades, exhibiting by about 10% average annual growth in production. Capture fisheries, although still the major source of supply of fish, have become static or are in decline due to over‐fishing and environmental degradation, and it is now believed that aquaculture has the greatest potential to meet the growing demand for fish from the increasing population. At present, aquaculture production accounts for about one‐third of the total fish production in Bangladesh. This paper examines the impact of an aquaculture development project in Bangladesh on food security, with particular emphasis on the poor. The analysis shows a positive impact of aquaculture development on employment, income and consumption. A number of implications for policy in areas that might strengthen these outcomes are discussed and recommendations are presented.     

海水贝类养殖中的问题及对策

正近几年,海水养殖业规模迅速扩大,产量大幅度增加,养殖形势及前景良好。继藻类和虾类养殖产业发展高潮之后,贝类养殖已发展为世界最大规模的养殖产业,对沿海经济的发展发挥着重大作用。但由于养殖户发展养殖生产的积极性无度发挥,片面追求高产,重数量、轻管理,过多地消耗资     

养殖刺参保苗期重大疾病“腐皮综合征”病原及其感染源分析

2003～2005年冬、春季,山东省和辽宁省众多养殖区域的保苗期刺参(Apostichopus japonicus)暴发了较为严重的传染性疾病-"腐皮综合征".该病波及面广,传染性强,死亡率常高达90%以上.发病症状主要表现为厌食、摇头、肿嘴、排脏、身体萎缩、口部溃烂乃至体表大面积溃疡.本研究对症状较为典型的3家海参保苗期的发病幼参进行了详细的病原学分析,从所有病参的病灶组织分离得到了1种占有绝对优势的菌株,经人工感染实验证明它对健康刺参具有较强的致病性,且感染病参的症状与自然发病海参的症状相同.通过形态学、生理生化和16S rDNA分子生物学方法对该菌进行的分类鉴定表明,导致保苗期刺参"腐皮综合征"的致病菌是假交替单胞菌(Pseudoalteromonas nigrifaciens).同时也对3家养殖场刺参保苗养殖系统进行了分析研究.结果表明,水源中细菌含量不高,为(0.8×102)～(1.2×102)cells/mL,其特征与病灶处优势菌不同;而饵料中细菌含量最高可达3.2×106 cells/mL.饵料、池水和池底污物的优势菌与病灶处优势菌基本一致,说明饵料可能是病原菌的主要来源.本研究首次揭示了"腐皮综合征"导致保苗期刺参大规模死亡的原因及其致病原,对刺参健康养殖和病害防治具有重要的指导意义.     

Nitrification kinetics of biofilm as affected by water quality factors

Various types of fixed film biofilters have been used in recirculating aquaculture systems under different water quality and operating conditions. The effectiveness of the nitrification process can be evaluated by nitrification kinetics. Nitrification in the bacterial film of the biofilter involves physical, chemical and biological processes that are governed by a variety of parameters such as substrate and dissolved oxygen concentrations, organic matters, temperature, pH, alkalinity, salinity and turbulence level. The impacts of these parameters upon nitrification kinetics make predicting the performance of a biofilter for a given application an engineering challenge. Knowing the performance of a biofilter is critical for both designers and managers. This paper summarizes the current knowledge on nitrification kinetics as affected by the aforementioned factors based on literature and the results from the authors’ laboratories. These factors were ranked according to their significance of impact on biofilter nitrification performance. The information presented can be used as a reference for the design and operation of biofilters in recirculating aquaculture systems.     

水泥池悬挂毛刷丛养殖罗非鱼试验

在水泥池中悬挂毛刷丛,利用其附着的微生物藻类形成的生物膜净化养殖水体水质,进行奥尼罗非鱼(T.aureus♀×T.nilotica♂)养殖试验。试验从2011年5月6日开始,在4口露天水泥池中共投放全长2～3 cm奥尼罗非鱼苗2 400尾,经182 d的养殖,2口试验池共收获1 179尾,平均体重197g/尾,成活率98.25%,总产量232.25 kg;2口对照池共收获906尾,平均体重197.6 g/尾,成活率75.50%,总产量179.02 kg。试验结果表明,试验池能提高水体透明度、维持水温相对稳定和净化水质,实现不换水或少量换水的目的,达到健康养殖的功效。     

Fitting growth with the von Bertalanffy growth function: a comparison of three approaches of multivariate analysis of fish growth in aquaculture experiments

Three approaches for multivariate analysis of fish growth in aquaculture experiments with Nile tilapia (Oreochromis niloticus niloticus L.) based on the von Bertalanffy growth curve are presented and compared. The approaches are: an extended Gulland‐and‐Holt (GH) plot, a forced extended GH plot and a multilinear regression analysis for the growth parameter K. All three models provide valuable insight into the major environmental factors influencing the daily growth rate and explain 28–46% of the variance of the observed daily growth rate of the used data set. For all three methods, the modelled parameter is significantly related to the net yield of Nile tilapia and can, therefore, be used for the predictive modelling of management scenarios. The extended GH plot loads the influence of environmental parameters upon L_∞, while the forced extended GH plot and Direct fitting of K load the influence on the growth parameter K. The latter is more in the tradition of aquaculture research. But the forced extended GH plot and Direct fitting of K can only be applied if L_∞ of the cultured species is known, as the selected L_∞ influences the variance in the regression variables.     

大西洋鲑循环水养殖水体异养细菌组成的研究

采集养殖池水样,选取Zobell 2216E琼脂培养基、溶菌肉汤琼脂培养基、硫代硫酸盐柠檬酸盐胆盐蔗糖琼脂培养基、脑心浸液琼脂培养基、胰蛋白胨大豆琼脂培养基、营养琼脂培养基6种常见固体培养基进行细菌分离培养,以平板菌落计数法和菌落外观形态特征辨别及16SrRNA基因测序方法进行异养菌计数和种类组成分析。结果显示:(1)养殖池水体异养菌可分为4大类,分别属于变形菌门(包括α-、γ-变形菌纲)、厚壁菌门、拟杆菌门、放线菌门,其中以γ-变形菌纲为优势菌群。按属分类大多为假交替单胞菌属和弧菌属。(2)不同培养基分离菌落数量2216E培养基溶菌肉汤琼脂培养基胰蛋白胨大豆琼脂培养基脑心浸液琼脂培养基营养琼脂培养基硫代硫酸盐柠檬酸盐胆盐蔗糖琼脂培养基,且2216E培养基菌落数极显著高于其余5种培养基(P0.01);2216E培养基所分离细菌的种类最多,分属于12个属,假交替单胞菌属为优势类群,占比50%,弧菌属仅占3.13%;脑心浸液琼脂培养基、溶菌肉汤琼脂培养基、胰蛋白胨大豆琼脂培养基所分离细菌均以弧菌属为优势菌群,分别占33.33%、60%、25%;硫代硫酸盐柠檬酸盐胆盐蔗糖琼脂培养基所分离细菌仅分属于1个属,即弧菌属;营养琼脂培养基无弧菌,但有假单胞菌分离出。     

我国水产养殖保险发展的几点建议

水产养殖业是风险较大的产业,水产养殖者在水产养殖的过程中,难免遭受自然灾害和意外事故,保险机构如能对水产养殖者所遭受的经济损失及时提供经济保障,必将为水产养殖业的稳定发展起到重要作用。本文对中国水产养殖保险发展现状、必要性及存在的问题等进行了阐述,并提出一些建议。     

基于16SrDNA比较研究混养三角帆蚌和鲢鳙对池塘养殖水体微生物群落结构的影响

为了研究混养三角帆蚌(Hyriopsis cumingii)和鲢(Hypophthalmichthys molitrix)鳙(Aristichthys nobilis)对池塘养殖水体微生物群落结构的影响,分别在浙江海盐、江西九江、上海浦东开展了罗氏沼虾-三角帆蚌混养、草鱼—三角帆蚌混养、罗氏沼虾-三角帆蚌-鲢鳙鱼混养三组系列实验。利用DGGE技术对养殖水体的16S r DNA进行指纹图谱分析。三组实验共鉴定出57条不同条带,每组实验中混养三角帆蚌或鲢鳙实验组的平均条带数均高于单养水体水样平均条带数。Shannon多样性指数分析结果显示,各养殖水体混养三角帆蚌、鲢鳙后,多样性指数均有所增加。PCA分析和DGGE聚类结果显示,在无鲢鳙的情况下,蚌与主养物种(罗氏沼虾、草鱼)混养实验组的16S r DNA图谱聚为一类,显示出蚌对于微生物群落结构影响的贡献;在同时引入鲢鳙和蚌的情况下,16S r DNA指纹图谱则是按照有无鲢鳙聚为两类,提示在本实验中鲢鳙对于水体微生物的影响要大于蚌。对DGGE图谱其中20条显著条带进行回收、测序和系统发育分析,结果表明,所获序列主要分属于放线菌门(Actinobacteria,25%)、蓝藻门(Cyanobacteria,25%)、α-变形菌亚门(Alphaproteobacteria,15%)、β-变形菌亚门(Betaproteobacteria,15%)、γ-变形菌亚门(Gammaproteobacteria,10%)、ε-变形菌亚门(Epsilonproteobacteria,5%)、裸藻叶绿体(Euglenales,5%)。