Water Quality in Laboratory Soil-Water Microcosms with Soils from Different Areas of Thailand

Forty-five soil samples were collected from aquaculture areas in 23 provinces of Thailand to include six soil orders and wide variation in physical and chemical properties. Soil-water microcosms were prepared containing 5 g of soil and 150 mL of distilled water. Microcosms were held on an oscillating table shaker (150 rpm) for 1 wk at 25 C in the dark. Water pH and concentrations of dissolved nutrients, total alkalinity, and total hardness were measured. Differences in properties within soil orders caused wide variation in composition of solutions and differences in concentrations of dissolved substances and pH were not related to soil order. Regression analyses revealed significant correlations between concentrations of soil nutrients extractable in dilute acid (0.05 N HCI plus O.025 N H₂SO₄) or in neutral, 1 N ammonium acetate and aqueous concentrations. Regression coefficients usually were higher for dilute-acid extractable nutrients than for ammonium acetate extractable ones. Regression coeficients based on dilute-acid extractable nutrients follow: soluble reactive phosphorus ( r = 0.816); calcium ( r = 0.685); magnesium ( r = 0.470); potassium ( r = 0.959); sodium ( r = 0.977); manganese ( r = 0.462); boron ( r = 0.399). The correlation between soil and solution iron was not significant and aqueous concentrations of copper and zinc were below detection limit. Hardness was correlated with soil carbon ( r = 0.710) and soil pH was a good predictor of alkalinity ( r = 0.877). Soil pH and aqueous pH were highly correlated (r = 0.939). Findings suggest that soil characteristics can be used to predict pH and concentrations of several dissolved substances in soil-water systems under aerobic conditions.     

Aquaculture Net Drag Force and Added Mass

The hydrodynamic loads on plane net samples of differing mesh geometry are measured in steady and oscillating flows. The steady loads on plane nets are also numerically simulated. The net is modeled as an inter-connected system of lumped masses and springs. The loads are computed for each twine segment and applied to the lumped masses at the segment ends. The equations of motion are formulated for the coupled dynamics of the masses and solved numerically. Drag data from the experiments is compared with analytical and numerical models and existing empirical formulae. Results for steady flows indicate that drag coefficients for nets and cylinders, as a function of the Reynolds number, have identical trends with consistent offsets. It is concluded that the drag coefficient for nets is equivalent to the drag coefficient for cylinders (and spheres for knotted nets) modified by a function of net solidity. For unsteady flows, the drag and added mass are extracted from the total wave force by applying a vector approach. It is shown that drag and added mass coefficients are not well quantified by conventional non-dimensional parameters (i.e. Keulegan–Carpenter and Reynolds numbers). The unsteady drag coefficient is presented as a function of wave particle velocity, wave period and net porosity. It is proposed that the added mass coefficient be expressed by an assumption of an effective thickness—conceptually the width of water affected by the net, which is a function of wave frequency and net solidity.     

Chemical Characteristics of Bottom Soils from Freshwater and Brackishwater Aquaculture Ponds

Soil chemical analyses were conducted on samples from 358 freshwater fish ponds and 346 brackishwater shrimp ponds. Freshwater ponds were located in Honduras, Rwanda, Bhutan, and the United States. Ponds in the United States were in Alabama, Georgia, Mississippi, Florida, and South Carolina. Brackishwater ponds were in Thailand, Ecuador, Philippines, and Venezuela. Soils of freshwater and brackishwater ponds did not differ greatly in average concentrations and concentration ranges for carbon, nitrogen, calcium, and pH. Concentrations of copper and barium tended to be higher in freshwater soils than in brackishwater ones. All other measured chemical constitutents tended to be more abundant in the soils of brackishwater ponds than in those of freshwater ponds. For the most part, ranges of pond soil chemical properties were similar to those of terrestrial soils, with freshwater pond soils resembling terrestrial soils from humid areas and brackishwater soils being similar in many respects to soils of arid regions. However, some brackishwater pond soils were highly acidic, acid-sulfate soils. Data were arranged into concentration categories (very low, low, medium, high, and very high) to facilitate comparisons of the present data set with other data on soil chemical properties for aquaculture ponds. All ponds included in the present study were used for aquaculture, showing that it is possible to rear fish and shrimp across an extremely wide range of soil chemical properties.     

酶联免疫吸附法在水产养殖中的应用

简要介绍了酶联免疫吸附法，并且就其在水产养殖中的应用进行了较详细的评述，主要包括ELISA用于水产品安全检测、水产动物病原菌检测和水产养殖其它领域的应用，旨在能促进该技术在水产养殖领域中的发展。     

磷脂的功能及其在水产养殖中的作用

磷脂具有多重营养作用，作为饲料添加剂已广泛应用于饲料工业，并取得了较好的经济和社会效益。就磷脂的结构和性质、饲用磷脂的种类以及磷脂的功能作用作一介绍，着重阐述了磷脂在水产养殖中的作用，包括在海水鱼类、淡水鱼类和甲壳类养殖中的作用，对磷脂在水产养殖上的开发前景作一展望。     

养殖水环境中磷的循环与平衡

详细地介绍了养殖水环境中磷的各种存在形态及其相互之间的转化和循环过程，同时总结了前人研究和提出的各种养殖水环境中磷的物质平衡模型，为优化水产养殖和保护水环境提供科学依据。     

Economics of Sustainable Intensification of Aquaculture: Evidence from Shrimp Farms in Vietnam and Thailand

There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm‐level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm‐level natural resource use efficiency. Additional research that incorporates economic analysis into on‐farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.     

水产养殖容量研究进展及应用

近30年来,全球水产养殖产量以接近9%的年增长率持续增长。快速发展的水产养殖业在保障世界粮食供应的同时,也带来环境污染和生物多样性下降等一系列生态环境问题,引起国际社会的广泛关注。水产养殖的资源和环境承载力,即养殖容量与生态容量问题,已成为水产养殖业可持续发展中迫切需要解决的问题。本文概述了水产养殖容量和环境容量概念的起源及其发展,例举了养殖容量研究的代表性成果,分析了养殖容量的估算方法及养殖容量模型的发展历程,并探讨了其存在问题以及在水产养殖管理中的应用前景,以期推动以养殖容量评估为基础的水产养殖区规划。水产养殖容量的科学评估与综合应用,可在一定程度上解决制约水产养殖业可持续发展的生态环境问题,并为建立基于生态系统的水产养殖管理与空间规划提供科学依据。     

水产养殖容量的研究

本文讨论了水产养殖容量的概念及其理论基础，评述了各种研究方法的长处和局限性，并在此基础上对网箱养殖容量的扩大途径作了理性归纳。     

Evaluation of Lime Requirement Procedures and Liming Materials for Aquaculture Ponds in Thailand

Abstract

There were strong correlations between soil pH and pHof water (R² = 0.810) and total alkalinity (R² = 0.724) in laboratory soil-water systems prepared with acidic rainwater and pond soil samples from Thailand. Moreover, water pH and total alkalinity were highly correlated (R² = 0.987). Although soil carbonate concentration was not correlated with total alkalinity, there was a correlation between the product of soil carbonate and soil organic carbon and total alkalinity (R² = 0.482). Other soil properties, exchange acidity, cation exchange capacity, base saturation, and total sulfur, were either not correlated or weakly correlated with total alkalinity. Total alkalinity did not exceed 20 mg/L except in systems with soils containing free carbonate. A method that estimates the amount of liming material needed to completely base-saturate bottom soils and provides an excess of carbonate, should be used in Thailand and other places. Calcitic agricultural limestone gave higher total alkalinity concentration in soil-water systems than dolomitic agricultural limestone. There usually would be no justification for selecting higher-priced dolomitic limestone for use in ponds.     

Nitrogen,Phosphorus, and Carbon Concentrations in Some Common Aquaculture Feeds

Nitrogen, phosphorus, and carbon concentrations were measured from 203 samples of starter, fingerling, and grower aquaculture feeds from several countries and for several common species. The feed protein concentrations reported by manufacturers often were slightly greater than the measured crude protein concentrations. The correlation coefficients (R²) between feed nitrogen and carbon concentrations were less than 0.50, and nitrogen and phosphorus concentrations in feed were not correlated. There were considerable differences in elemental concentrations among feeds, but the overall averages for carbon, nitrogen, and phosphorus concentrations, respectively, were as follows: starter feed 41.36, 7.78, and 1.57%; fingerling feed 39.75, 5.95, and 1.36%; grower feed 39.97, 5.36, and 1.22%. Concentrations of carbon, nitrogen, and phosphorus in feeds are required in estimating the pollution potential of aquaculture facilities. The crude protein concentration – if provided by the manufacturer – can be used to estimate nitrogen concentration in feed, but carbon and phosphorus concentrations should be measured.     

4种金属离子对养殖水体中磷的去除作用的研究

对4种金属离子Al^3 、Ca^2 、Fe^3 、Fe^2 单因子和双因子联合作用对养殖水体中磷的去除效果进行研究。结果表明，单因子作用中以Al^3 和Ca^2 除磷效果较好，除磷率可达50％以上。双因子联合作用中，Al^3 -Fe^2 、Ca^2 -Fe^3 、Ca^2 -Fe^2 除磷效果较为显著，可达60％～76％。     

流沙湾水产养殖区浮游动物群落特征

于2012年5月–2013年1月对流沙湾海区浮游动物进行了周年性的季度调查,共检出浮游动物41种、幼体17类,以桡足类居多(29种)。亚强次真哲水蚤(Subeucalanus subcrassus)、短尾类幼虫(Brachyuran larva)、长尾幼体(Macruran larva)在四季均有出现,并在3个季度中成为优势种。年均浮游动物丰度和生物量分别为48.12 ind./m3、13.43 mg/m3。扇贝主养区、鱼类网箱养殖区和珍珠贝养殖区的各季浮游动物丰度及生物量均低于对照区(非养殖区);大中型浮游动物主要出现在对照区,而在鱼、贝养殖区极少出现。冬季扇贝主养区多样性指数为各区最高,其浮游动物丰度、生物量迅速回升,高于鱼类网箱养殖区和珍珠贝养殖区,但仍低于对照区。研究结果显示,鱼、贝养殖区域流沙湾海区的浮游动物丰度及生物量比往年明显减小,浮游动物的小型化加剧。     

电站库区水域养殖渔业权探析

《渔业法》1986年颁布实施以来,对我国渔业资源的管护和渔民权益保护都起到了重要的作用;物权法的颁布确立了渔业权,对完善渔业法律具有重大意义。本文根据多年的库区水域渔业开发管理的实践探索,针对生产实践存在的问题,提出完善渔业权制度建设的建议,以促进渔业生产持续健康发展。     

浙江象山港的养殖容量研究和水产养殖的可持续发展

养殖容量是近年来一个新的研究领域，我国在这方面的研究进展较晚，且在实际生产中往往被人们所忽视。本文就象山港水产养殖存在问题进行了分析，并从养殖容量和环境生物修复等方面如何搞好象山港水产养殖可持续发展谈了几点看法。     

不同修复方式下养殖池塘底质营养物质的迁移特征

自2013年12月8日起至2014年5月5日,以养殖池塘污染沉积物为研究对象,采用室内模拟法研究了种青、暴晒、投放生石灰等方法修复淡水养殖池塘沉积物的效果。结果表明,在池塘沉积物修复期,种青组沉积物中总氮和总磷的含量、碱性磷酸酶的活性、烧失量均显著低于对照组(P0.01);生石灰组沉积物中烧失量显著低于对照组(P0.01)。覆水处理后,种青组水体中正磷酸盐、叶绿素a含量显著高于对照组(P0.01),种青组水体总磷含量低于对照组(P0.05);暴晒组水体中正磷酸盐、总磷含量低于对照组(P0.05);生石灰组水体中各项指标均无明显差异。分析结果表明,种青、暴晒、投放生石灰降低了养殖池塘底泥中营养物质的含量,其中种青组沉积物中总磷的含量降低显著,覆水后水体中总磷的含量也有明显降低,以种青组的综合修复效果最佳。     

象山港中部养殖海区营养盐的季节变化及富营养化

根据2014年11月,2015年1月、3月和7月在象山港中部养殖海区开展的海洋调查所获得的海水营养盐数据,分析了该海域营养盐含量的季节变化,评价了海水的富营养化状况。结果显示,该海域无机氮平均含量秋季最高,春季次之,冬季最低;活性磷酸盐平均含量秋季最高,夏季次之,冬季最低。对不同养殖区域分析,宁海海藻养殖区和西沪港海带养殖区的无机氮浓度除冬季1个站位点外均劣于国家海水四类水质标准(0.50 mg/L),活性磷酸盐浓度在春、秋两季劣于国家海水四类水质标准(0.045 mg/L)。全年各水层的N/P比值均高于Redfield比值,磷相对缺乏。根据富营养化评价模式,象山港中部养殖海区营养水平属于磷中等限制潜在性富营养型。     

锦江河沉积物磷形态与吸附行为及磷释放风险

研究沉积物磷的吸附参数、形态及其含量,揭示锦江河及其支流沉积物磷吸附行为的变化特征及其环境意义,阐明锦江河及其支流富营养化风险。2016年1月,在锦江河及其支流9个样点用彼得森采泥器采集表层沉积物,测定磷吸附平衡浓度(EPC_0),计算沉积物磷吸附指数(PSI)、磷吸附饱和度(DPS)以及其衍生出的磷释放风险指数(ERI)。结果表明,锦江河沉积物4种形态磷含量顺序为CaCO_3~PFe(OOH)~PASOPP_(alk),CaCO_3~P是沉积物磷的主要存在形态;钙结合态磷(CaCO_3~P)和磷最大吸附量(Q_(max))显著正相关;沉积物中PSI为11.24~31.37(mg P/100 g)/(μmol/L),平均值为21.28(mg P/100 g)/(μmol/L),且PSI与Q_(max)显著正相关;DPS值在水平方向上和垂直方向上的分布均与PSI值的分布相似;EPC_0在各支流分别从上游到下游逐渐减小,下游的沉积物磷释放潜能相对上游较小;EPC_0的垂直分布表明,对大多数河段来说,疏浚并不能减小沉积物磷释放风险;所有采样点的ERI在水平方向上均超过了25%,各采样点沉积物磷潜在释放诱发富营养化的风险均为高度风险。     

3种微藻对海水集约化对虾养殖尾水氮磷的去除效果

基于对虾生物絮团集约化养殖尾水含有高浓度硝态氮和磷酸盐的特征，比较分析钝顶螺旋藻（Spirulina platensis）、牟氏角毛藻（Chaetoceros muelleri）、盐藻（Dunaliella sp.）3种微藻在配制尾水中的存活生长状况及其对无机氮磷的去除效果，以期筛选出适宜的微藻用于后续尾水净化技术。采用显微镜计数法测定藻细胞密度，国标法测定总无机氮、氨氮、硝态氮、亚硝态氮和磷酸盐的含量。结果显示，钝顶螺旋藻在实验前后的藻细胞密度变化不大（P>0.05），约为3.32×106 个/mL和5.88×106 个/mL；牟氏角毛藻和盐藻细胞密度有明显增加（P<0.05），分别从初始的4.00×104 个/mL和2.50×105 个/mL升高至实验结束时的1.66×106 个/mL和1.06×107 个/mL。经过16 d实验，钝顶螺旋藻组对硝态氮和总无机氮去除率分别为79.60%和46.06%，显著高于其他各组（P<0.05），第8天时对磷酸盐的去除率可高达98.55%；牟氏角毛藻组16 d的磷酸盐去除率为98.25%，显著高于其他各组（P<0.05）。研究表明，3种微藻均可在对虾养殖尾水环境中存活，且对尾水氮磷具有较好的净化效果。