Chemical Budgets for Polyethylene-lined, Brackishwater Ponds

Budgets for water, nitrogen, phosphorus, chemical oxygen demand (COD), and dissolved oxygen (DO) were estimated from May to October 1986 in three 0.09 ha ponds stocked with striped bass Morone saxatilis (Walbaum). Ponds were lined with highdensity polyethylene sheeting to prevent seepage. Pond bottoms, except for side slopes, were covered with soil. Total rainfall roughly equalled evaporation. Liner runoff augmented rainfall inflow by 43%. The largest source of nitrogen input was feed -88% of the measured input. Overflow was the greatest measured loss of nitrogen. Denitrification and ammonia volatilization apparently removed large amounts of nitrogen. Feed applications and runoff were the major phosphorus inputs. Fish harvest and uptake by mud represented the major losses of phosphorus. The production of each kilogram of fish required 2.09kg of feed and released to the water, as metabolic waste, 118.55g nitrogen, 1.2g phosphorus, and 1.67kg COD. Metabolic wastes from fish resulted in the production of an additional 3.71kg of COD in phytoplankton and benthic algae. Thus, 1kg of live striped bass resulted in a total of 5.38kg of COD. Benthic respiration exceeded respiration of microorganisms in the water column. Total respiration exceeded oxygen produced by photosynthesis, but diffusion of oxygen from the atmosphere into the ponds was sufficient to maintain adequate DO concentrations for fish survival.     

Estimation of Oxygen Transfer Rates for Mechanical Aerators in Brackishwater Aquaculture Ponds

Oxygen transfer rates for mechanical aerators are usually determined by standard aeration tests conducted in concrete tanks. Results from standard tests are then extrapolated to field application of the aerators in aquaculture ponds, but these extrapolations have not been verified. In this study, oxygen transfer rates were estimated for propeller-aspirator-pump aerators deployed in brackish water aquaculture ponds under normal pond conditions. Estimation was accomplished by fitting the Whole Pond Respiration Diffusion (WPRD) model to nighttime observations of dissolved oxygen concentration for ponds in which artificial aeration had been initiated during the night. Application of this new technique revealed that oxygen transfer rate determined from a standard aeration test was similar to that estimated from trials in aquaculture ponds. Preliminary results suggest that oxygen transfer rates were higher when the aerator was placed in the deep end of the ponds than when the aerator was situated in the shallow end. Aeration efficiencies ranged from 1.45 to 1.8 kg O ₂ per kW-hour.     

Anaerobic Treatment of Brackishwater Aquaculture Sludge: An Alternative to Waste Stabilization Ponds

Environmental pressure, land utilization, and economic feasibility have resulted in the development of recirculating aquaculture systems (RAS). For many RAS, sludge is collected and washed from the system to waste stabilization ponds (WSPs). However, disposal of brackishwater aquaculture sludge into WSP is often prohibited because the high salinity can interfere with treatment. Moreover, there are problems associated with WSPs because of elevated salt content, such as the common practice of reusing treated water and land application of stabilized sludge. We tested and compared the treatment of brackishwater aquaculture sludge in an upflow anaerobic sludge blanket (UASB) reactor as an alternative to a WSP. In UASB, wastewater flows upward through a blanket of granular sludge and is treated by anaerobic micro‐organisms. Reduction in organic matter and 5‐d biochemical oxygen demand by 97 and 91%, respectively, was achieved in a UASB as compared to corresponding reductions of 22 and 41% in a WSP. During the UASB digestion process, methane is produced and recovered. Overall, a reduction in potential environmentally harmful factors such as salinization, land requirements, greenhouse gas emissions, as well as transportation costs are achieved, making the UASB reactor an attractive possible alternative for saline aquaculture sludge management.     

Evaluation of a Kit for Estimating Organic Matter Concentrations in Bottom Soils of Aquaculture Ponds

Abstract The Hach CEL/700 Organic Matter Laboratory provided estimates of organic carbon concentrations in pond soil samples comparable to those obtained by the commonly-used Walkley-Black method. Dry ashing at 350–400 C tended to overestimate soil organic matter concentrations, and this procedure requires too much equipment and laboratory expertise for use on most aquaculture farms. The Hach kit can provide practical aquaculturists a simple and reliable method for measuring organic matter in pond soils. Samples from brackishwater ponds should be treated with mercuric sulfate to prevent chloride interference and overestimation of organic matter.     

Liming and Fertilization of Brackishwater Shrimp Ponds

Agricultural limestone and burnt lime are applied either to the water during shrimp production or to pond bottoms between shrimp crops. However, unless the total alkalinity and total hardness of pond water is below 50 mg/L as equivalent CaC0₃ or the pond soils are acidic (pH < 7), liming is of little or no value. The use of burnt lime should be avoided because this material can cause high pH in water and soil. Chemical fertilizers or manures are used to fertilize brackishwater ponds. Fertilization programs for brackishwater ponds usually require more nitrogen (N) than those for freshwater ponds. Phosphorus (P) fertilization is important both in brackishwater and freshwater ponds. Because water is exchanged often in brackishwater ponds, fertilizer should be applied in small doses and at frequent intervals. Most managers of brackishwater ponds prefer a large proportion of diatoms in the phytoplankton community. An N:P application ratio of 20:l in ponds favors diatoms; in fiberglass tanks with water of low silica concentration, fertilization with silica encouraged an abundance of diatoms.     

池塘半封闭淡化养殖斑节对虾试验

探讨了在池塘条件下半封闭式淡化养殖斑节对虾的技术，成功地将斑节对虾养殖环境的盐度下限控制在1～2。通过培养基础饵料、科学驯养和使用微生物制剂等手段，使对虾的平均单产达到了3812kg／hm^2，产值达到10．8万元／hm^2。     

阿维菌素对池塘水质和浮游生物群落结构的短期影响

在湖北省公安县崇湖渔场3口面积均为0.268hm2的主养草鱼池塘中,施用剂量0.0375mL/m3的阿维菌素后,于第2、3、4、5、6d采样,测定池塘水质及浮游生物群落结构的短期变化。研究结果表明,阿维菌素可使池塘水体硝态氮水平显著下降,亚硝态氮、铵态氮和总氮水平显著上升;而对总磷、可溶性磷酸盐和pH值的影响不显著。施用阿维菌素前共镜检出浮游植物6门80种,浮游动物32属41种;用药后共检出浮游植物7门94种,浮游动物38属48种。其中,原生动物消失10种、新增9种,轮虫消失5种、新增10种,桡足类新出现3种成体。绿藻消失9种、新增10种,硅藻消失1种、新增8种,裸藻消失2种、新增7种,甲藻和金藻各新增1种。施用阿维菌素后,浮游动植物优势种显著变化,小型浮游植物种类增多。阿维菌素导致原生动物和枝角类的密度和生物量显著下降,桡足类数量显著上升,而对轮虫密度和生物量影响不大;同时裸藻、蓝藻、甲藻等部分浮游植物密度和生物量剧烈波动;使用阿维菌素的池塘易发生裸藻水华,应慎用阿维菌素。     

中华绒螯蟹池塘生态养殖群体生长特征研究

池塘种植水生植物,生态养殖河蟹.河蟹大部分群体表现为幼蟹、成蟹阶段分别脱壳10次和5次左右,并且不同的生长阶段表现不同生长特性,体长（头胸甲长）随生长期呈指数增长（y=0.2656e^0.2145x,R^2=0.978）;部分群体出现早熟和2年以后达到性成熟的晚熟现象.     

暗纹东方鲀池塘养殖试验

1 验地点与池塘条件　在绍兴县海涂九三丘养殖场,2口池塘,面积2 667m^2.池深1.8 m,池底淤泥厚5 cm,水源充足,水质清新.进排水及供电等设施良好.闲置育苗温室作越冬池.     

黄颡鱼池塘主养技术的研究

试验鱼池0．67hm^2，投喂自制饲料，饲养245d，产黄颡鱼3406．4kg，折合单产5109kg/hm^2，均尾重135g。搭养鲢、鳙、鲂鱼，总产5605．9kg，产值79486元，折合119229元／hm^2，纯利润36786元，折合55179元／hm^2。     

淡水白鲳鱼苗的池塘培育试验

利用5口面积均为533m^2的池塘，采用清水下塘豆浆喂养法，进行了淡水白鲳苗种池塘培育试验。经20d培育，试验组的平均成活率为84．0％，对照组的平均成活率为62．5％，表明淡水白鲳鱼苗培育采用清水下塘为宜。     

Chemical and Physical Properties of Shrimp Pond Bottom Soils in Ecuador

Chemical and physical analyses were conducted on bottom soil samples from 74 brackish-water ponds representing 40 shrimp farms in Ecuador. Most ponds had soils with pH > 6 and total carbon concentrations < 2.5%. Carbon was mostly in organic form, for the average concentration of carbonate carbon was 0.06%. The C: N ratio was 8 to 10 in soils with < 2.5% carbon. In ponds built in former mangrove areas, soil carbon was > 2.5% and C: N ratios were 25 to 30. Ponds soils in former mangrove areas also tended to be high in total sulfur and low in pH. Lack of correlation between carbon and sulfur in mangrove soils suggested that most of the sulfur was inorganic and presumably in sulfides. Soils containing above 0.4% free carbonate (as equivalent CaCO₃) had pH values > 7. Although carbonate concentration was a major factor controlling soil pH, calcium hardness of pond waters was strongly influenced by salinity (and calcium) in the water supply. Total phosphorus concentrations averaged 898 mg/kg, and dilute acid extractable phosphorus usually accounted for 25–35% of the total. Concentrations of major cations and minor elements varied greatly in soils and exhibited ranges of up to three orders of magnitude. Contrary to opinions of shrimp producers, many pond soils in Ecuador are not acidic and few soils have a high organic matter content. Proper use of soil and water testing could greatly improve the efficiency of liming and other soil management practices.     

Potassium Adsorption by Bottom Soils in Ponds for Inland Culture of Marine Shrimp in Alabama

Potassium is applied to correct ionic imbalance in pond water for inland culture of marine shrimp in Alabama. This study evaluated the loss of potassium through adsorption by bottom soil. Adsorption by bottom soils of potassium added in fertilizers continued over 4 yr. Exchangeable potassium concentration in bottom soils did not increase after the first year, but potassium loss to bottom soil continued over 4 yr. Laboratory work on soil–water systems contacted bottom soil with potassium‐enriched pond water for 8 mo: nonexchangeable potassium fixation accounted for 75% of potassium adsorption. Soil total potassium adsorption averaged 518 mg/kg. Bottom soil samples exposed to consecutive 50 mg/L potassium solutions (potassium chloride in distilled water) and agitated by shaker led potassium adsorption by soil to decline from 406 mg/kg in first exposure to 70 mg/kg in sixth exposure. During the next six exposures, potassium adsorption was similar, between 61 and 95 mg/kg in each exposure, averaging 1804 mg/kg of potassium. Pond soils contain smectite clay, have a large capacity to adsorb potassium by nonexchange processes, and remove added potassium from water for years. The only reliable way to determine when potassium fertilizer may be added to Alabama inland shrimp ponds is to monitor potassium concentration in water.     

北京地区养殖池塘底泥中重金属的分布及污染特征

调查结果显示,北京地区养殖池塘底泥中铬、铅、汞、锌、铜的含量分别为93.6(50.3~172)mg/kg(干)、32.2(20.1~185.8)mg/kg(干)、0.136(0.009~0.742)mg/kg(干)1、09.4(61.1~235)mg/kg(干)和57.8(18~155)mg/kg(干)。北京地区养殖池塘底泥中重金属含量相对较高,其中部分池塘中铜和汞的含量超过国家土壤环境质量Ⅱ级标准。采用单项污染指数法和综合污染指数法对北京地区养殖池塘底泥中重金属的污染状况进行了评价。北京地区养殖池塘底泥中铅的污染等级为安全级;锌的污染处于警戒线;铬、汞和铜为轻度污染。     

Viability of a Freshwater Mussel (Elliptio complanata) as a Biomechanical Filter for Aquaculture Ponds II: Effects on Aquaculture Pond Water Quality

Bivalves have been proven to be an inexpensive method for removing suspended solids, dissolved nutrients, and controlling algal growth through suspension feeding. The freshwater mussel, Elliptio complanata, is one of the most abundant species in Delaware, and it is additionally favorable for this experiment because of its hardiness against environmental stress and its filtration efficiency. This study examines the possibility that biomechanical filters such as E. complanata can supplement existing chemical and mechanical filtration regiments in aquaculture pond management. Twelve earthen aquaculture ponds located at the Delaware State University were stocked at a density of 4,000 catfish (Ictalurus punctatus) per hectare. Four different concentrations (0, 75, 150, and 300) of E. complanata were placed in trays within the ponds with three replicates of each concentration. The trays were suspended 15 cm below the surface of the water for a period of five months. Fish were fed a 32% protein diet twice daily at a rate of 1% of their body weight. Water quality was analyzed weekly while fish and mussel growths were measured biweekly. Results from water quality parameters varied significantly and were not conclusive based on the data obtained in this study. Water quality did not improve within the mussel treatment ponds during the course of this study and was found to be significantly below that of control ponds for all of the water chemistry parameters measured, with the exception of ammonia. Catfish in the 150 mussel treatment ponds grew the fastest; the 75 mussel treatment provided the most growth in mussels; and the 300 mussel group maintained the highest mussel survivorship. Although there were differences between ponds, fish growth and survivorship were not significantly different between treatments. While our mussel densities may have not been sufficient, their placement within the water column may have added additional stress. Being removed from the sediment can result in a decreased clearance rate in a benthic species such as E. complanata. This study may not have been conclusive in proving that mussels can be used to maintain water quality in aquaculture ponds, but we did see positive growth and survivorship of mussels and fish that indicated that the mussels were thriving in the aquaculture pond setting. This study may show that aquaculture ponds provide a suitable habitat in which propagated mussels may be held until their release into native areas.     

藕塘养殖鲶鱼生态试验

池塘面积4hm^2，栽种鄂莲4号浅水莲藕种3750kg／hm^2，投放50尾／kg的鲶鱼种7500尾／hm^2、草鱼夏花2万尾；共收获白莲藕90000kg、鱼4500kg，毛收入10．45万元，纯收入4．65万元，投入产出比为1：1．8；为当地调整养殖品种结构探索了一种新模式。     

暗纹东方鲀池塘健康养殖技术总结

经过5个月的养殖,通过调节水温,改善池塘条件,搭放鲢、鳙鱼及使用生物活性剂改良水质等技术手段,2.65 hm^2池塘共产河鲀11723 kg,平均产量达4424 kg/hm^2,成活率95%,饵料系数2.0,与温室养殖相比,其饵料系数低,用电、用药少,鱼体几乎无药物残留,是一种较为理想的健康养殖方式.     

Ecology of Blue-Green Algae in Aquaculture Ponds

Cyanobacteria (blue-green algae) in the genera Anabaena, Aphanizomenon, Microcystis, and Oscillatoria often form extensive and persistent blooms in freshwater aquaculture ponds. Bloom-forming cyanobacteria are undesirable in aquaculture ponds because: 1) they are a relatively poor base for aquatic food chains; 2) they are poor oxygenators of the water and have undesirable growth habits; 3) some species produce odorous metabolites that impart undesirable flavors to the cultured animal; and 4) some species may produce compounds that are toxic to aquatic animals. Development of cyanobacterial blooms is favored under conditions of high nutrient loading rates (particularly if the availability of nitrogen is limited relative to phosphorus), low rates of vertical mixing, and warm water temperatures. Under those conditions, dominance of phytoplankton communities by cyanobacteria is the result of certain unique physiological attributes (in particular, N₂ fixation and buoyancy regulation) that allow cyanobacteria to compete effectively with other phytoplankton. The ability to fix N₂ provides a competitive advantage under severe nitrogen limitation because it allows certain cyanobacterial species to make use of a source of nitrogen unavailable to other phytoplankton. The ability to regulate cell buoyancy through environmentally-controlled collapse ad reformation of intracellular gas vacuoles is perhaps the primary reason for the frequent dominance of aquaculture pond phytoplankton communities by cyanobacteria. Cyanobacteria that can regulate their position in the water column gain a distinct advantage over other phototrophs in poorly mixed bodies of water. In addition to the physicochemical interactions that influence phytoplankton community dynamics, cyanobacterial-microbial associations may play an important regulatory role in determining community structure. Cyanobacteria are always found in close association with a diverse array of microorganisms, including eubacteria, fungi, and protozoans. These associations, which in the past have often been viewed as antagonistic, are increasingly seen as mutualistic and may function in a positive manner during bloom development.     

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。     

鱼种池套养泥鳅试验

选择0．48hm^2的1号塘为试验池塘，0．53hm^2的2号塘为对照塘，进行鱼种池套养泥鳅养殖试验。养殖9～10个月，1号塘总产2795kg，其中泥鳅770kg，总收入21942元。折合45712元／hm^2，纯收人15962元，折合33255元／hm^2；2号塘总产2424kg，总收入16713元，折合31348元／hm^2，纯收人10606元。折合19875元／hm^2。池塘常规养殖套养泥鳅可增加渔业产量，提高经济效益。