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  • 2018 Volume 45 Issue 6
    Published: 20 December 2018
      
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  • Effect of biofilm culturing methods on start-up of fluidized-sand biofilter (FSB) and structure of bacterial community#br#
    ZHANG Haigeng, SHAN Jianjun, GU Chuanchuan, GUAN Chongwu, ZHANG Yulei，NI Qi
    2018, 45(6): 1.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
     In order to explore the effect of biofilm culturing methods on start-up time of fluidized-sand biofilter (FSB) and structure of microbial community, understand the water purification mechanism of FSB, and apply it to Chinese sturgeon recirculating aquaculture system, the start-up time of FSB when using natural biofilm culturing method and inoculating probiotics was studied, and the change of structure of the microbial community in FSB at different times was analyzed with pyrosequencing method. The results showed that the start-up time of FSB when inoculating probiotics was significantly shorter than that when using natural biofilm culturing method. At the early period of biofilm culturing, the microbial species on the surface of filter material carrier was few, and the predominant bacteria were firmicutes. After the biofilm got mature, the diversity of bacterial community in the biofilter when using natural biofilm culturing method was significantly higher than that when inoculating probiotics, the community structure was more stable, and the proportion of functional bacteria was also higher than that of the inoculation method, such as Flavobacterium and purple nonsulfur bacteria, which indicated that the natural biofilm culturing method was more conducive to the stable operation of FSB.
  • Comparison of effects of semi-enclosed and enclosed recirculating aquaculture of Anguilla rostrata#br#
    LE Pumin, JIANG Xinglong
    2018, 45(6): 7.
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    To improve the water saving, water quality and culture effects of recirculating aquaculture of Anguilla rostrata, one semi-enclosed recirculating aquaculture system was upgraded to construct the enclosed recirculating aquaculture system by adding the units such as moving bed biofilm reaction pool, and comparative experiments on aquaculture were carried out with a duration of 180 d. Results showed that the yield per unit, final weight, final weight increment and daily water recirculation rate of enclosed recirculating aquaculture (treatment group) were 62.8 kg/m3 , 621.7 g, 3.28 g and 92% respectively, which were 15.4%, 15.5%, 16.3% and 73.3% more than semi-enclosed recirculating aquaculture (control group) respectively (P<0.05); feed coefficient in the treatment group was 1.55, significantly 12.5% less than the control group (P<0.05); the concentrations of total nitrogen, nitrate nitrogen, nitrite nitrogen, ammonia nitrogen, labile phosphorus and total phosphorus in the treatment group were respectively 14.8%, 37.0%, 42.6%, 79.1%, 17.9% and 15.6% less than the control group(P<0.05). Compared with semi-enclosed recirculating aquaculture, enclosed recirculating aquaculture of Anguilla rostrata had the advantages of improving water recirculation rate, improving water quality, increasing yield per unit and growth rate, and reducing feed coefficient and morbidity.
  • Study on the effect and mechanism of ozone on purification of recirculating aquaculture water
    GUAN Chongwu, ZHANG Yulei, SONG Hongqiao, ZHANG Haigeng, WANG Jian
    2018, 45(6): 14.
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    In order to investigate the effect and mechanism of ozone on purification of the aquaculture water in the circulating water system, experiments on the effects of three different ozone dosages on the organic pollutants, ammonia nitrogen and nitrite in the water are carried out, and on this basis, the mechanism of purification is analyzed. The results show that ozone preferentially reacts with organic pollutants, followed by nitrite, and then oxidizes ammonia nitrogen; ozone selectively removes organic pollutants, preferentially reduces UV254 and water color, has no obvious effect on COD and DOC treatment, but can significantly improve the biodegradability of aquaculture water; 15mg/L ozone dosage can achieve more economical and effective purification effect;UV254, nitrite, water color and COD can be reduced by 73.86%, 92.35%, 37.52% and 16.43% respectively. DOC / UV254 can be increased to 448.86 (cm · mg) / L, significantly improving the biodegradability of aquaculture water. The research shows that the ozonation technology plays a good role in the purification treatment of aquaculture water. It is important to select the appropriate ozone dosage for different conditions to improve the efficiency of purification treatment.
  • Research on application of bio-floc in industrial recirculating aquaculture of shrimp
    BAO Ying1, SUN Xiwu2, JI Aibing3
    2018, 45(6): 19.
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    In production of Litopenaeus vannamei of industrial recirculating aquaculture, for aquaculture of shrimp smaller than 4cm, the recirculating model has obvious defects. It is easy to block the drain filter, the shrimp fails to take food effectively and water quality worsens. In this research, in combination with theories and research results about application of bio-floc to aquaculture at home and abroad, bio-floc is used to control water quality in juvenile shrimp feeding stage, and technical key points including floc formation time, type of carbon source added, volume of addition and adding mode are studied preliminarily; after 25 d of no water change, the survival rate of juvenile shrimp is 72.8%, and individuals are uniform. The research shows that the use of floc-based aquaculture model in the early stage shrimp bleeding can effectively solve such problems as uneven growth of juvenile shrimp in recirculating aquaculture system and low survival rate, and improve the overall success rate of shrimp in industrial recirculating aquaculture model.
  • Experiment on application of bio-floc technology in industrial aquaculture of Litopenaeus vannamei
    DONG Yang, FU Shuyuan, MENG Aiyun, YANG Hekun
    2018, 45(6): 26.
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    In order to study the change trend of water quality indicators and culture effect in culture ponds of Litopenaeus vannamei under the condition of set density, bio-floc technology was used to carry out the culture experiment in an outdoor recirculating aquaculture facility. The fingerling size was 0.158 g/ind, stocking density was 600 ind/m3,  3 concrete ponds with an area of 15 m2 were selected for test, and culturing cycle was 120 d. The results showed that: during the culture experiment period, for aquaculture water in the 3 ponds, the average concentration of ammonia nitrogen was (0.81±0.99)mg/L, the average concentration of nitrite nitrogen was (2.00±3.96) mg/L, pH was 7.48±0.36, and the average concentration of vibrio was (120±77) cfu/mL; after 120 d of culture, the average length of shrimp was (14.022±0.269) cm, and the average weight of shrimp was (15.748±1.803) g. The research showed that using bio-floc technology in outdoor recirculating aquaculture concrete pond for aquaculture of Litopenaeus vannamei has the advantages of high aquaculture survival rate, low water exchange rate and high aquaculture yield, and has broad application prospects.
  • Research on flow resistance of Litopenaeus vannamei related to industrial culture
    DONG Ying, LIU Wei, GUI Fukun, PAN Yun, FENG Dejun
    2018, 45(6): 32.
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    In industrial shrimp culture, it is necessary to control the flow velocity in the pond and the duration of the flow according to the flow resistance of the shrimp and in combination with the effect of the accumulation of pollutants. In this research, vertical circulation flume tank was used to measure the sustainable swimming time of Litopenaeus vannamei (3.62±0.50 g) under five flow velocity levels (20.3, 23.0, 30.2, 34.9 and 41.3 cm/s), and the time was taken as the index to assess its flow resistance at corresponding flow velocity. The results showed that at the same flow velocity, the sustainable swimming time varied significantly among the shrimps having similar external characteristics. The characterization parameter for the variation (coefficient of variation) increased and then decreased with the increasing flow velocity, peaking at 34.9cm/s. The relationship curve of cumulative fatigue percentage and swimming time indicated that for the high velocity cases (30.2, 34.9 and 41.3 cm/s), nearly 50% of the shrimps got fatigue within 10 min and could not swim anymore. The coefficient R2 for curving fitting showed that exponential function could express the relationship between average sustainable swimming time and flow velocity best. The findings in this research suggested that it is not only to take the average flow resistance of shrimp but also the variation of flow resistance among shrimps into consideration when performing the flow control in industrial culture. For the shrimp (3.62±0.50) g used in this research, the flow velocity in the pond should be controlled below 30.2 m/s, and the duration of the flow at corresponding flow velocity should be decided based on the relationship cure of cumulative fatigue percentage and swimming time.
  • Research on daily feeding rhythm of cage-captured and electrofishing Monopterus albus#br#  
    LIU Yaqin, LV Weiwei, YUAN Quan, ZHOU Wenzong
    2018, 45(6): 38.
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    In order to enhance the survival and health status of Monopterus albus in early stocking, the variation of food consumption rate of cage-captured and electrofishing Monopterus albus was studied indoor under weak light less than 100lx and limitless consumption, and the effects of domestication on daily feeding rhythm were discussed. The research found that food consumption of electrofishing Monopterus albus was mainly at 19:00-22:00 (P<0.01), while cage-captured Monopterus albus had no apparent peak of food consumption (P>0.05). The electrofishing, cage-captured and domesticated Monopterus albus all showed apparent diurnal feeding rhythm (P<0.05): more active food consumption at night than that by day, and ceased food consumption for some periods by day. The Monopterus albus domesticated at 18:00 had one peak of food consumption at 18:00-19:00 daily (P<0.01), and there was no significant difference in proportion of food consumption between Monopterus albus feeding once a day and once every two days (P >0.05). The research showed that there was a definite diurnal feeding rhythm on Monopterus albus, electrofishing Monopterus albus also could be used in artificial breeding, and domestication at afternoon would help Monopterus albus to form a single peak diurnal feeding rhythm.
  • Design of production device for knot rope oyster seedling string
    LI Haiyun, QIU Rongbin, YE Dapeng
    2018, 45(6): 46.
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    In response to the problems that oyster seedling string is produced with high labor intensity, high labor cost and low work efficiency, a kind of automatic production device for knot rope oyster seedling string is developed. The device takes the nylon rope, PVC belt and rust-proof magnesium alloy wire as processing raw materials and PLC as the core to control stepping motors and cylinders, so as to combine the processes including punching, wearing rope, wire delivery, wire cutting, knotting, cutting and folding together in one working process. Through the man-machine interface, it can realize real-time working status monitoring, real-time modification of process parameters, real-time data base and alarm, etc. The prototype test finds that the average success rate of automatic production of seedling string is over 96.55 %，and the device runs stably and reliably and has strong practicability, which reduces labor intensity and labor cost and improves production efficiency. The design may provide reference for the development and application of the automatic production device of the fixed shellfish sampler.
  • Hydrodynamic analysis of combined pyramidal artificial reef 
    ZHAO Lin1,2, DENG Chao1, YU Zhenjiang1, SUN Liyuan3, TU Zhong3, ZHENG Zhongqiang1, CHANG Zongyu1,2
    2018, 45(6): 53.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
     Artificial reef is an important part of marine ranching, which is of great value for the restoration of marine ecological environment and the improvement of fish catch. Placement of artificial reef can make the flow field around change, which has an important impact on fish feeding and sheltering. This paper studies hydrodynamic characteristics of artificial reef, and analyzes the flow field of combined pyramidal artificial reef with Fluent and based on N-S equation. By comparing the flow field changes under 4 different flow rates (0.1, 0.2, 0.3 and 0.4 m/s), the distribution characteristics of vortices and pressure around are obtained. Three-dimensional turbulent zone of such artificial reef is provided and compared with other types of artificial reef. The results show that the vortex is mainly distributed in the rear area of the diversion tray, and the farther, the weaker; at different flow rates, the maximum height of the ascending flow is about 1.53 times of the height of the reef, the height of the reef vortex area is about the height of the artificial reef, and the length of the vortex zone increases with the velocity of the water; at different flow rates, the range and size of the turbulent zone remain the same..
  • Research on development status and countermeasures of intelligent aquaculture in China#br#
    GONG Muge, MENG Feiliang, HUANG Yixin, ZHOU Haiyan
    2018, 45(6): 60.
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    China has entered the critical stage of accelerating the transformation of traditional fisheries into modern fisheries, breaking through the constraints of resources, environment, and food safety. It is necessary to use intelligent aquaculture to promote the upgrading and transformation of traditional aquaculture methods. That expounds the important significance of developing intelligent aquaculture, introduces the development status of intelligent aquaculture in China, the future development trend of intelligent aquaculture, and puts forward the development suggestions of intelligent aquaculture in China. In order to provide reference for the development of intelligent aquatic equipment research in China.
  • Effect of enzymatic hydrolysis optimization on the functional properties of Euphausia superba Dana protein#br#
    SHI Zhouming1,2, CHEN Xuezhong1, LIU Zhidong1, QU Yinghong3
    2018, 45(6): 67.
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    Euphausia superba Dana is a kind of polar marine life with huge resources and high nutritional value. Its high protein content and amino acid composition in line with the high quality protein standards of Food and Agriculture Organization (FAO) and World Health Organization (WHO) make it high quality protein with a good potential for development and utilization. With Euphausia superba Dana protein as raw material, effects of enzymatic hydrolysis on its functional properties (water absorption, oil absorption, emulsibility and foamability) were investigated. The assessment methods of functional properties of Euphausia superba Dana protein were international general methods for assessment of functional properties of food protein. Enzymatic hydrolysis could improve oil absorption capacity, emulsibility, foamability and foaming stability of Euphausia superba Dana protein, improve its functional properties in a targeted way, and improve the feasibility of practical application of Euphausia superba Dana protein and its derivatives. Researches showed that enzymatic hydrolysis could improve the functional properties of Euphausia superba Dana protein and broaden its application field and scope.
  • Analysis of resistance characteristics of 33.2 m ocean-going double deck trawler #br#
    LI Na, LIANG Jiansheng
    2018, 45(6): 74.
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    In view of the requirements of ocean-going trawler renovation and reconstruction project in China, it is required to design standard ship types that meet the requirements of main small and medium-sized ocean-going trawlers. In this paper, the resistance characteristics of 33.2 m ocean-going double deck trawler are analyzed theoretically based on the regression polynomial of residual resistance of Oosterveld in Dutch pond, and the resistance characteristics of CFD fishing vessel are analyzed by solving N-S equation with Flow-3D fluid analysis software, VOF method and RNG k-e model. Resistance towing tests are carried out in the towing tank of the ship model. The mathematical model of resistance regression suitable for small and medium-sized fishing vessels is determined through comparison and analysis, and the accuracy and feasibility of CFD analysis are verified. The precision and accuracy of resistance characteristic analysis of standardized ocean-going fishing vessels are improved with comprehensive analysis method, and the technical scheme of low resistance performance optimization of standardized fishing vessels is studied and formed. The real ship saves energy of more than 20% in pilot application, which is in line with the upgrading and reconstruction target of “safe, energy-saving, economical, environmental and livable” ocean-going fishing vessels.
  • Research on engine exhaust-powered absorption refrigerating device of fishing vessels#br#
    HUAGN Wenyun1,2, ZHAO Xinying1,2, JI Yuzhao1, DING Yiming3
    2018, 45(6): 81.
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    The engine exhaust-powered refrigerating device recovers and converts exhaust heat of propulsion diesel engine of fishing vessels into energy for cold storage of fishes. It can improve fresh-keeping quality of the fishes and reduce the workload of the fishermen without increasing the energy consumption, which is in line with the national policy guidelines of energy conservation and consumption reduction. According to the target ship type and equipment parameters, a set of practical ammonia water absorption refrigeration system for fishing vessels was designed. The basic laws of thermodynamics were used to establish a mathematical model, analyze the parameters of each state point of the refrigeration system, and combine the energy conservation and mass conservation laws to calculate the whole system performance indicators. Finally, the variation of cooling capacity and refrigeration coefficient was obtained while the parameters such as generator heat load, solution pump and cooling water were changed. The device has been verified by multi-voyage operation on vessels, and the cooling effect is significant; however, the energy utilization efficiency of the system is low and needed to be improved by quantifying model parameter.