Table of Content

25 December 2018, Volume 40 Issue 6

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Numerical research of the tidal currents in Sansha Bay

2018, 40(6):  413-424. 

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Applying the 2D hydrodynamic model to simulate the tide currents in the study area of Sansha Bay，this paper investigated the distribution of currents based on the topography in 2014，and discussed the situation in 1974 on different environment. The present study also analyzed the characters of tide currents between 1974 and 2014. As the results revealed， the currents in Sansha Bay was rectilinear flow，whose direction was dramatically affected by the topography and which reflected the character of terrain in Sansha Bay. The magnitude in deep groove or bay mouth was larger than that in shallow and was over 1.0 m/s， but less than 0.5 m/s in others. Generally， the magnitude in ebb tide was larger than that in flood tide. By contrast， the land reclaim over several years has affected the batliymetry and currents in Sansha bay， excepting the magnitude increasing in some area. Most of the areas decreased with ranging from 15% to 30% ， but with less change for direction.

Isolation, identification and antibiotic sensitivity analysis of bacterial pathogen from Larimichthys crocea with gill-rot disease

2018, 40(6):  425-433. 

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In 2013, the large yellow croaker (Larimichthys crocea) cultured in net cage at Ningde was diseased.The sick fish appeared symptoms of gill filaments ulcers and gill rakers bare. One dominant bacterial strain, named as Lc-2013-G1, was isolated from the gill of sick L. crocea. The strain Lc-2013-G1 was confirmed to be a bacterial pathogen of L. crocea by arificial infection. Physiological and biochemical characteristics showed that the pathogen Lc - 2013 - G1 formed a smooth, moist, marginally yellow colony on the TCBS medium, which was Gram - negative and arc - shaped rod. The strain Lc - 2013 - G1 had motility and grew in a medium containing 6% sodium chloride. The indicators of V-P, arabinose, sputum matrix andcitrate were negative to Lc-2013-G1, while the indicators of galactose, catalase and amylase were positive to Lc-2013-G1. The pathogen Lc-2013-G1 was determined to be Vibrio ponticus based on morphological and physiological detection, biochemical tests and 16S rRNA gene analysis. Antibiotic sensitivity analysis indicated that the pathogen Lc-2013-G1 was sensitive to Ampicillin, Polymyxin B, Sulimethoxazole, Norfloxacin, Piperacillin, Gentamycin, Cefoperazone, Ofloxacin, and so on. The results provided a reference for the prevention and treatment of large yellow croaker disease caused by Vibrios.

Analysis of bacterial communities‘ structure in intestinal flora of Trichiurus haumela based on high - throughput sequencing

2018, 40(6):  434-440. 

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The structure of bacterial communities in intestinal flora of Trichiurus haumela was studied using high - throughput sequencing technology. As a result, a total of 36， 129 valid sequences were obtained,and clustering to 245 OUTs. Except for 4 sequences (0. 01%) could not be species classified，the rest belonged to 16 phyla，including 77 families， 127 genera. At the level of phylum， Proteobacteria was overwhelmingly dominant with high relative abundance up to 52.30%， followed by Firmicutes (30.66%) . At the level of genus， Photobacterium (47.90%) of Vibrionaceae (49.38%) and Candidatus 一 Arthromitus(17.04%) of Clostridiaceae一 1 (25.40%) were the main genera. Alpha diversity analysis showed that， the OTU dilution curve flatten out gradually，and the Good，s Coverage index was 100%， while the depth was large enough.

The effect of feeding frequency on the growth and plasma anti-stress enzyme activities of hybrid grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂) in industrialized recirculating aquaculture systems

2018, 40(6):  441-448. 

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The experiment was conducted for 60 days in order to determine the effects of different feeding frequencies (1 time per day, 2 times per day, and once every 2 days) on the growth and plasma anti – stress enzyme activities of the hybrd grouper ( Epinephelus fuscoguttatus 5 x E. lanceolatus $ ) with initial weight of (297. 79 ±59. 94) g at water temperature of ( 29. 96 ± 0. 40 ) °C ! reared with arificial fomulated in industrial recirculating aquaculture systems. The results showed that the survival rate of the fish fed once every 2 days (99. 39 ±0. 01) % was significantly higher than those of the fish fed once per day (96. 75 ±0. 66 ) % and twice a day (97. 08 ±0. 66 ) % ( P <0. 05) . There were not significant effects on the specific growth rate (SGR = 1 .0 5 ~ 1 .1 9 ^ ^ d ) , condition factor ( CF = 1. 63 ~ 1. 77 ) , relative weight gain ( RWG = 187. 65% ~205. 04% ) , daily weight gain ( DWG = 4. 33 ~ 5. 00 g/d ) , coefficient of size variation ( SV = 14. 50 ~18. 30) , food intake ( FF = 1. 07 ~ 1. 24 % /d ) , food conversion efficiency ( FCE = 81. 77% ~ 87. 38% ) and food conversion ratio ( FCR = 1. 15 ~ 1. 25 ) among the three groups ( P >0. 05 ) . The plasma anti – stress enzyme activities ( i. e. AKP = 8. 07 ~ 8. 26 King100mL, CAT = 1. 92 ~ 2. 52 U/mL and SOD = 23. 39 ~24. 34 U/mL) of the fish was not significantly different in all treatments ( P >0. 05) . Under the experimental conditions, the feeding frequency of once every two days could be used to improve the survival rate of the hybrid grouper ( Epinephelus suscoguttatus 5 x E. lanceolatus $ ) in industrial recirculating aquaculture systems .

Suitability evaluation of deep - water cage aquaculture based on GIS --- taking Changhai County as an example

2018, 40(6):  449-457. 

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The rigid constraints of the marine environment and the fierce competition from the sea use of various industries have led to the continuous extrusion of marine aquaculture areas, especially in coastal waters. Therefore, deep-water cage aquaculture (DWCA) has gradually become an emerging industry in mariculture. Thus the spatial planning of DWCA has become a necessary research topic. Suitability evaluation is a process of grading for a certain type of development or utilization, based on analyzing its suitability, which is often used in planning. Changhai County is affiliated to Dalian, Liaoning Province, China. Changhai sea area (38°55'47〃N ~39°34'10〃N) is located in the northern part of the Yellow Sea. This paper constructed the suitability evaluation index system for DWCA and takes Changhai sea area as the case to study the spatial distribution of the suitability of DWCA based on GIS technology. According to the guiding principle, difference, data availability and comprehensive constriction principle of the evaluation index system, 11 indicators were selected to establish a system framework based on natural and social factors. The value of the evaluation index weight reflected the degree of influence of the indicator in the evaluation index system, which were determined by the analytic hierarchy process. At last, the weighted comprehensive index method was used to calculate the suitability index. For natural suitability, some unsuitable areas for DWCA were mainly caused by the low concentration of chlorophyll a and high comprehensive pollution index of water quality. According to the distribution of natural suitability index, the suitability index was the highest in the sea area near Wumang Island, Zhangzi Island, Gexian Island and Guanglu Island, followed by the sea area among Xiaochangsiian Island, Wumang Island and Haiyang Island. The suitability of the outer seas of the southeastern par of Changsiian Island was higher than that of the northwestern par of the coastal waters. For the social suitability, the distance from town would affect the convenience of aquaculture operations. From the perspective of social suitability index distribution, the degree of suitability was centered on land and islands, and was concentrically distributed to the sea.The comprehensive evaluation index were obtained through weighted calculating natural and social suitability. The results showed that the suitable sea area for DWCA was 3 527. 94 km2, accounting for 32.7% of the total sea area of Changhai County. The most suitable sea area for DWCA was distributed around the western par of Guanglu and Gexian Island, the southern par of Zhangzi Island, the sea area between the Shicheng Island and Wumang Island, and the southern par of the Haiyang island, with an area of 1 248. 38 km2, accounting for 11. 57% . The higher suitability sea area was widely distributed around Zhangzi Island, Haiyang Island, Wumang Island and Xiaochangsiian Island, covering an area of 2 279. 56km2, accounting for 21.13%. Due to the combined effects of Chlorophyll concentration and distance from town areas, it was not suitable for DWCA area mainly distributed in sea areas far away from land and islands, with an area of 814. 81 km2, accounting for 7. 56% . Other sea areas were medium suitability. The study could provide reference for the sea planning and sea area management of aquaculture in Changhai County.

Optimization of ultrasonic-assisted cellulose extraction technology for Ulva lactuca functional oligosaccharide

2018, 40(6):  458-468. 

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Based on single factor experiments, the quadratic orthogonal rotational combination design was adopted to obtain the optimal processing conditions of ultrasonic - assisted cellulose extraction for Ulva lactuca functional oligosaccharide. Results showed that the optimal extraction processing conditions were cellulose dosage of 430 U/g, solid - liquid ratio of 1:30 (g/mL) , ultrasonic temperature of 50°C， ultrasonic time of 1.5 h，extract solution pH of 5. 0 and ultrasonic power of 450 W. Under the optimal extraction processing conditions，the extraction yield of Ulva lactuca soluble carbohydrate was 12. 02% . Then，with subsequent polysaccharides and protein removing operations， the extraction yield of Ulva lactuca functional was 2.38%.

Study on aluminum adsorption behavior of jellyfish

2018, 40(6):  469-477. 

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Traditionally，Alum is needed during the processing of jellyfish，resulting in high residual aluminum content in jellyfish products. In order to study the aluminum adsorption behavior of jellyfish，jellyfish was used as the main research object. Six representative seafood samples， including clam， sea cucumber，oyster， razor clam， squid and shrimp were selected as the control. The aluminum adsorption capacity of jellyfish soaked in 1% alum solution for 7 days was determined， while the amino acid composition and content of each seafood were also analyzed. The results showed that the amount of aluminum adsorbed by jellyfish was significantly higher than that of other seafoods，up to 2. 11 X 104 m/kg ( dry basis) . Amino acid composition analysis showed that the lowest total amino acid content of jellyfish was 0. 015 7 g/100g，indicating that jellyfish had strong aluminum adsorption capacity under very little dry matter，and this strong aluminum adsorption capacity was related to the composition of jellyfish amino acid， especially with the high glycine，glutamic acid，aspartic acid，and proline ratio，as well as the low composition of phenylalanine，leucine，and methionine ratio.

Concentrations and risk evaluation of four kinds of heavy metals in fishing aquatic products of the central and northern sea areas of Fujian Province

2018, 40(6):  478-489. 

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In order to understand the metal pollution and human health risk of fishing aquatic products, this article analyzed concentrations of Pb, Cd, Hg and inorganic arsenic in fishing aquatic products which included 160 samples and 18 species from the central and northern waters of Fujian during 2014 and 2015. Single factor pollution index ( Pi ) and metal pollution index ( MPI) were used to evaluate the degree of pollution, and provisional tolerable weekly intake ( PTWI) and carcinogenic risks were used to assess the edible safety and health risk，respectively. The results showed that the contents of Pb，Hg and inorganic arsenic in fishing aquatic products were in line with national standards，while the content of Cd reached the criteria of pollution，with the exceeding rate of 9.4% . Pi indicated that the fish was not obviously polluted by heavy metals， which was basically in good state，while Cd in 0ratosquilla and crab reached the criteria of “heavy pollution”and others were in good state. The MPI result showed that the heavy metal pollution in the shellfish was more serious than that in the fish. The edible safety assessment indicated that intake of four kinds of heavy metals by eating fishing aquatic products were lower than those formulated by FAO and JECFA monthly tolerable intake，but the Cd intake of a minority of shellfish was exceeded the PTWI value. The model estimation for health risk indicated that concentrations of heavy metal did not exceed the recommended maximum acceptable levels set by International Commission on Radiological Protection ( ICRP) . 0verall，although fishing aquatic products in Fujian Province can be safely consumed，potential risk of Cd still calls for further attention.

Comparison of the growth and survival rate of three cultured abalone varieties in natural sea areas during the summer

Zhi-Sen CHEN

2018, 40(6):  490-495. 

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Haliotis discus hannai is one of the most important cultured shellfish in Fujian Province，which was introduced from the northern cold water areas. However，in recent years，large-scale mortality of H. discus hannai often occurred when it was cultured in Fujian natural sea areas during high temperature period in summer， which led to great losses to farmers. In order to find an alternative variety with better tolerant ability to high temperature，Quanzhou Fisheries Technology Station introduced two new varieties of abalone，named Lupan abalone and Xipan abalone which were bred by abalone researchers in Xiamen University in 2016. In this study， we tested and compared the high temperature tolerance and growth of the two new varieties with H. discus hannai. The survival rates of Lupan abalone and Xipan abalone were 65. 60% and 76. 67%, respectively by the end of summer，82% and 113% higher than H. discus hannai (36. 00%) ，respectively. After 15 months of culture，the average wet weight of Lupan abalone and Xipan abalone reached 89. 24 g and 67. 96 g respectively，which was 81% and 37% heavier than H. discus hannai. In summary，Lupan abalone showed obvious advantages in the growth and survival rate，which was considered as an alternative abalone variety to solve the problem of high summer mortality in H. discus hannai culture in southern China.

Study on the hybrid pelteobagrus (Pelteobagrusvachelli♀×Pelteobagrusfulvidraco♂) pond aquaculture twice a year in north Zhejiang Province

2018, 40(6):  496-500. 

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In order to explore the feasibility of the culture model of raising hybrid （Pelteobagrusvachelli♀×Pelteobagrusfulvidraco♂) twice a year in pond in north Zhejiang，hybrid Pelteobagrus fry cultured in pond once a year and juvenile cultured in pond twice a year were contrasted. The results showed that hybrid Pelteobagrus juveniled cultured in pond twice a year harvested larger commercial fish with higher survival rate and price. Also，hybrid Pelteobagrus juvenile cultured in pond twice a year could shorten culturing period and quicken the return of funds，obtaining higher unit benefit and economic benefit. Hybrid Pelteobagrus juvenile cultured in pond twice a year was more valuable to be promoted in north Zhejiang Province.