2007  Vol. 3  No. 5

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Research Paper
Abstract:

Antibiotic susceptibility tests were carried out by K-B diffusion method on 41 vibrio strains isolated for one year both from farming seawater (18 strains) and digestion guts (23 strains) of the cobia, Rachycentron canadum. We chose 10 different species of antibiotics and refered to NCCLS performance standards for antimicrobial susceptibility testing, while taking Staphylococcus aureus ATCC25923 and Esсheriсhia coli ATCC25922 to control the test. Results showed that the most effective antibiotic for inhibiting growth of vibrio strains were Chloramphenicol (percentage of sensitive strains was 100%) and Gentamicin (percentage of sensitive strains from water and intestine was 100% and 90% respectively), followed by Norfloxacin, Compound Sulfamethoxazole Polymyxin B. It also showed that Penicillin G and Ampicillin were non-effective to majority of vibrio strains in the intestine, as 78% and 60% strains resisted to Penicillin G and Ampicillin respectively. Strains from farming water and intestine of cobia showed different sensitivity to the same antibiotic. 4 strains which resisted to 3 or more than 3 species antibiotics were sieved from this study.

Abstract:

The species, distribution, growth and propagation of the seaweed Gloiopeltis in coast of Guangdong province were investigated. The result is as follow. The main species of Gloiopeltis in coast of Guangdong province were G.tenax and G.furcata, in which the highest biomass of G.furcata reached 2 801.1 g · m-2. The other species of Gloiopeltis in Guangdong was G.complanata that was distributed in partial area. The biomass of Gloiopeltis in the east coast was higher than that in the west coast and was the highest in Daya Bay. Gloiopeltis was distributed in sea area which was high diaphaneity and high salinity with not lower than 20 for the surface layer of water salty and G.tenax was more obviously distributed in offshore than G.furcata. G.furcata was mainly distributed in mid-tidal area while G.tenax in lower mid-tidal area. The research also showed that Gloiopeltis could stand exposing to air for 6~8 h. Growth temperature for Gloiopeltis was lower than 23℃ and it grew faster while water temperature was below 18℃. The growth and disappear of Gloiopeltis was obvious different from the seasons. The reproductive organ of G.furcata formed in December to next year April while G.tenax formed in January to April in coast of Guangdong province.

Abstract:

The content of sulfate-reducing bacteria in the sediment of Dapeng′ao Cove marine culture cage area was determined by using the most probable number (MPN) technique. The results showed that the percentage detection of five sampling stations is 100%, the content of SRB in fish cage area was higher than that in control area and seashell area. The vertical content distribution of SRB is 1cm layer>5 cm layer>10 cm layer. The relationships among SRB content, sulfide, Eh, pH were discussed. The content of SRB is positively correlated with sulfide(R=0.96, P < 0.05), and significantly negative correlated with Eh (R=-0.97, P < 0.01).There is no significant relationship between the content of SRB and pH.

Abstract:

Based on the investigation data in May 2005, a GIS-based evaluation model was made, then the present status of the ecological environment quality in Daya Bay was accessed and the spatial distribution patterns of the quality were simulated. The results showed that the comprehensive quality index of the whole assessed sea area was 0.71±0.0568, which indicated the quality status was at the "better" level. There were three defects exposed in this assessment: eutrophic level of the water and the phytoplankton abundance were higher, the phytoplankton diversity was lower. The simulation of the environment quality′s spatial distribution patterns showed the whole maritime space assessed could be divided to three regions according to the grade of ecological environment quality: "the region with best quality", "the region with better quality", and "the region with fair quality", occupied 2.27%, 93.41% and 4.32% of the total area of waters assessed, the average comprehensive quality index were 0.80±0.0015, 0.71±0.0434 and 0.54±0.0304, respectively.

Abstract:

The spatial and temporal distribution characteristics of Pb in sediments from the cage culture area of Dapeng′ao Cove was studied through four times of investigation. The spatial distribution characteristics showed that the contents of Pb in sediments from cage culture area were significantly higher than that from shellfish culture area and control area. The vertical distribution characteristics showed that the disturbance in the layer from 0~15 cm of hole sediments was more evident and there was a decreasing trend of pb contents in cage culture area, but the vertical variations was not obvious in control area. The seasonal variations showed the similar characteristics in cage culture area, shellfish culture area and control area, and the contents of Pb in sediments were higher in spring and summer and lower in autumn, but the contents in cage culture area were higher than other areas. According to the results above, it was concluded that the content of Pb in the sediment of cage culture area was affected mainly by the activities of cage culture.

Abstract:

Based on the analysis of the microalgae samples collected from intensive higher-place prawn, semi-intensive earthen ponds and their intake canal in Zhanjiang, China in October 2005 and April 2006, a preliminary study was carried out on the microalgae community. The results showed that a total of 47 species of microalgae was identified in the culture ponds and intake canal, 28 species identified in spring and 21 species in autumn. The dominant species were Oscillatoria sp. and Cryptomonas erosa Ehr. The average variations of diversity (H′) were 2.29, 1.42 and 1.12 in Dongnan semi-intensive earthen ponds, Dongnan intensive higher-place ponds and Dongshan semi-intensive earthen ponds respectively in spring, 2.14 in intensive higher-place ponds and 1.62 in Dongshan semi-intensive earthen ponds in autumn, and it varied from 0.92 to 3.73 in the intake canal in the two season samplings. Average consistency of microalgae in autumn was higher than that of ponds in spring.

Abstract:

Genetic diversity and differentiation among three stocks of selected GIFT strains of Oreochromis niloticus was analyzed using microsatellite DNA and AFLP markers. Nine microsatellite loci and four primer pairs of AFLP revealed consistent results. Microsatellite data showed that Qingdao GIFT stock had the highest mean number of alleles (4.8), mean observed heterozygosity (0.528) and mean PIC (0.605), whereas Hainan GIFT the lowest. AFLP analysis demonstrated that Qingdao GIFT had the highest proportion of polymorphic loci (48.4%) and gene diversity within populations (0.245), whereas Hainan GIFT the lowest. These observations indicated that Qingdao GIFT has the highest genetic diversity, whereas Hainan GIFT the lowest. Genetic differentiation among the three GIFT strains was significant as revealed by microsatellite (FST=0.07~0.11, P < 0.01) and AFLP (FST =0.24~0.29, P < 0.01).AMOVA indicated that the majority of genetic variation (91.26% by microsatellite analysis and 67.6% by AFLP) was attributed to difference of individuals within stocks, suggesting that GIFT strains of O.niloticus has some potential for further selective breeding.

Abstract:

The chromosome specimens of high-finned grouper Cromileptes altivelis were obtained from metaphase of kidney cells by in vivo injection of PHA and colchicine, hypatoic-air drying technique, as well as Giemsa staining. The results showed that C.altivelis had a diploid chromosome number of 48 and its karyotype formula was 2n=48=48t, NF=48. Its karyotype was in accordance with the typical characters of higher location karyotype group of fish, but yet a relatively primitive one in Perciformes.

Abstract:

Genetic segregation of AFLP markers in three Pinctada fucata families, i.e. Indian family (Indian♀× Indian♂, PII), hybrid family (Sanya♀×Indian♂, PSI) and Sanya family (Sanya♀×Sanya♂, PSS) as well as their genetic variation was investigated. Three pairs of primers generated 57 loci, among which 57.4%~87.7% were segregated in F1. The proportion of loci segregated in Mendelian ratio over segregated loci ranged from 70.0% to 71.0%, of which 24.0%~45.2% segregated in 1 : 1 ratio. Hybrid family had the highest ratio of 1 : 1 segregating markers. The proportion of polymorphic loci was 93.0%~100.0% for the three families using 0.95 criterion. An overall genetic diversity (HT) was 0.460 and within-family genetic diversities (hS) were 0.434, 0.331, 0.366 for families PII, PSI, PSS, respectively, with an average of 0.377±0.030 (HS). Genetic differentiation among the three families was significant (GST=0.180). Analysis of genetic distances showed that Sanya family PSS was most distant from hybrid family PSI (0.157) while nearest to the Indian family PII (0.121).The UPGMA tree indicated that the two pure families PII and PSS were closely related and grouped together. These observations indicated that genetic variation in F1 family is high while genetic differentiation among families is great and significant. These findings shall be useful in management of genetic resources during breeding of pearl oysters.

Research Notes
Abstract:

Based on stepwise emendation, a procedure was designed to calculate the parameters of rope matching using VBA. This general program simplifed the rope matching test of a trawl, and improved the work efficiency and precision during rope matching.

Abstract:

Distribution of nutritional composition in muscle tissue was analyzed for rough-toothed dolphin (Steno bredanensis)from the South China Sea coast. Muscle samples were taken from back, belly and tail. The results showed that content of lipids in belly and protein in back muscle were highest. Composition of amino acids was extremely similarity. Glu was highest and Csy was lowest among 18 amino acids. No significant difference for fatty acids composition was observed in different samples. Typical fatty acids found in the major part of animals and fish oil, such as palmitic(16 : 0), palmitoleic acid(16 : 1), stearic(18 : 0), oleic(18 : 1), EPA(20 : 5 ω-3)and DHA(22 : 6 ω-3)dominated in the muscles of rough-toothed dolphin. Very close amount of SAF and MUFA were obtained, which were higher than total PUFA. The ratio of polyenes ω-3/ω-6 was about 0.12~1.36, which is normally higher than 4 and up to 50 in other marine organisms, this value was normally low. Muscles of dolphins were rich in Ca, Mg, Fe and trace metals such as Zn, Cu, Mn, Se. There was no significant difference for the distribution of these metals among muscle samples.

Review
Abstract:

The settlement risk in the international trade and the impact on China′s export of aquatic products caused by Renminbi appreciation was analyzed in this paper. We found that the increase tendency of China′s aquatic products export will continue, the international trade′s conditions of aquatic products for China will be improved and the market structure of aquatic products international trade will be changed, along with Renminbi appreciation. Some suggestions were proposed on speeding up market multiplex and the transformation of the mode of growth of foreign trade of the aquatic products.

Abstract:

The disease of sanguinicolid trematodes (Sanguinicolidae) has a serious impact on the aquaculture of some commercial important fishes (tuna, amberjack, etc). It occurs once a year, and its prevalence needs a certain water temperature range. The rates of infection and death are usually high in cultured fishes. Sanguinicolids from the wild fishes can infect the cultured ones in the same sea area, leading to heavy economic losses. Here we reviewed the recent studies on this disease, including the hazards, epidemic features and integrated control methods used recently. At the same time we summarized the problems need to be solved urgently. It can be a reference for further study on the control of the disease.