Abstract:An acute exposure experiment of copper on Pampus argenteus was carried out in a static biological test method.The abnormal rates of micronucleus and nucleus in peripheral blood cell, and the activities of antioxidant enzymes(SOD, CAT, GPX)in liver were determined under different copper concentrations.The results showed that the 48 h and 96 h median lethal concentrations of copper were 0.835 mg/L and 0.543 mg/L respectively, and the safe concentration of the metal was 0.054 mg/L.Copper was a drastic toxicant of Pampus argenteus, which indicated obvious dosage-effect relations with micronucleus rates and nuclear abnormal rates.Nuclear anomalies rates were generally higher than the micronucleus rates under the same concentration of copper;Activities of SOD, CAT and GPX changed greatly in the test groups which represented a tendency as increasing firstly and then decreasing from low concentration to high concentration.Antioxidant enzyme activity indicated parabolic dosage-effect relations.The changes of micronucleus rates, nuclear abnormal rates and the antioxidant enzyme activities(SOD, CAT, GPX)indicated the damage degree of Pampus argenteus by Cu²⁺.The SOD can also sensitively indicate early copper pollution of low concentration.

Abstract:An 8-week trial was conducted to investigate the effects of five carbon sources on the growth performance, intestinal biochemical parameters and water quality in the juvenile Megalobrama amblycephala by the principle of bio-floc technology(BFT).The carbon sources include starch(control), glucose, sucrose, sodium cyclamate, composite carbon(mixture of starch and glucose in proportion of 1:1).The juvenile M.amblycephala with initial body weight of(36.74±0.82)g were stocked into 15 indoor cement tanks(1 m×4 m×0.6 m)and fed commercial feed with daily normal feeding.At the initiation of the experiment, the fish were randomly chosen and sorted into 15 indoor cement tanks with 20 individuals per tank.Each experimental group was randomly assigned to triplicate tanks for a completely randomized design.The results of this study showed that bioflocs could effectively regulate water quality, as well as reduce ammonia and nitrite concentration.Final body weight, weight gain rate(WGR), specific growth rate(SGR)of glucose group were significantly higher than the other groups(P<0.05), while feed conversion ratio was significantly lower than the other groups(P<0.05).Furthermore, no significant differences(P>0.05)were observed for the survival rate and the body composition among all treatment groups.Intestine microstructure observation showed that there were some bioflocs in the brush border of intestine in juvenile M.amblycephal.The activities of protease and amylase of fish in the composite carbon group were significantly higher than control group, glucose group and sucrose group(P<0.05).The activities of superoxide dismutase and catalase of fish in the composite carbon group were 72.5% and 40.4%, which were significantly higher than those of control group, however, the malondialdehyde content was lower than that of control group(P<0.05).

Abstract:In order to investigate the digestive activity and non-specific immunity activity of GIFT Oreochromis niloticu cultured with biofloc technology(BFT), tilapia[(24.17±2.49)g]were raised in indoor recirculating aquaculture system(control group)and biofloc technology system(treatment group), respectively.During 59 days^, culturing, fluctuations of total ammonia nitrogen(TAN)and nitrite nitrogen(NO₂^--N)in the treatment group were(20.48±14.66)and(33.77±34.57)mg/L respectively, which were significantly higher than those of the control group.Final density(FD)in the treatment was as high as 36.89 kg/m³, individual weight(FIW), weight gain rate(WGR), specific growth rate(SGR)of the treatment group were significantly higher than those of the control group, and the feed conversion rate(FCR)decreased by 18.7%(P<0.05).Nitrogen utilization rate(NUR)of the treatment group was 57.79%, which was significantly higher than the control group(49.51%).Compared with the control group, activities of stomach protease, stomach lipase, intestine protease and intestine lipase of the treatment group were lightly lower, but there were no significant differences.Besides, total superoxide dismutase(T-SOD)activity in hepatopancreas of the treatment group was significantly lower than that of the control group, there were no significant differences of T-SOD, lysozyme(LZM)and alkaline phosphatase(AKP)activities in serum, hepatopancreas and head-kidney between the treatment group and the control group.

Abstract:A 92-d feeding experiment was conducted to investigate the effects of dietary graded level of linseed oil(LO)on growth performance, fatty acids composition and lipid deposition of liver and muscle in juvenile turbot(Scophthalmus maximus)[mean initial body weight, (5.89±0.02)g].Four isonitrogenous and isoenergetic practical diets were formulated with LO replacing 0%, 33.3%, 66.7% and 100% fish oil(FO), respectively.Each diet was randomly fed to triplicate groups in indoor seawater recirculation system to apparent satiation.The results showed that survival rate(SR)and specific growth rate(SGR)of juvenile turbot were independent of dietary LO level(P>0.05).With increasing dietary LO level, feed intake(FI)of turbot significantly increased, while feed efficiency(FE)and apparent net protein utilization(ANPU)significantly decreased(P<0.05), and they were up to the maximum and minimum in 100% LO group, respectively.Apparent digestibility coefficient of dietary lipid, hepatosomatic index and lipid content of muscle were also independent of dietary LO level(P>0.05).Lipid content of liver in turbot significantly increased with increasing dietary LO levels(P<0.05), which in 100% LO group was significantly higher than that in 100%FO group(P<0.05).Fatty acid composition of total lipid in liver and muscle was closely correlated with those in diets.With increasing dietary LO levels, the content of linoleic acid and linolenic acid significantly increased, while the content of EPA and DHA significantly decreased(P<0.05).These results suggested that on basis of nutritional quality, the LO replacement level in turbot diet should be lower than 66.7%, and the content of n3 very long chain-polyunsaturated fatty acid in the turbot diet should be higher than 0.8%.

Abstract:The present study was conducted to analyze the effects of dietary nucleotides on growth performance, intestinal morphology and anti-oxidative capacities of juvenile large yellow croaker(Larimichthys crocea)[initial weight:(7.71±0.02)g].Two control diets were set, which were high fish meal(FM, 45.0%)supplemented diet and low fish meal(N0, 31.5%)supplemented diet, respectively.Based on the latter, five graded levels of nucleotides were added.They were 75, 150, 300, 600 and 1 000 mg/kg, respectively.After the 9-week growth trial, results showed that survival rate, feed efficiency, feed intake and body composition of the animals were not significantly influenced by dietary nucleotides levels(P>0.05).Weight gain rates(WGR)of fish fed the diets with 300 or 600 mg/kg of nucleotides were significantly higher than those in the other groups(P<0.05).Dietary nucleotides significantly affected the total anti-oxidative capacity(T-AOC)and superoxide dismutase(SOD)activity in serum(P<0.05).Values of T-AOC and SOD increased first, and then declined as the dietary nucleotides levels increased.The highest values of these two parameters were found in the treatment with 300 mg/kg of dietary nucleotides.Dietary nucleotide significantly increased microvillus height(HMV)and the thickness of the muscular layer(TML)in the proximal intestine(P<0.05).The HMV in intestine of fish fed diet with 300 mg/kg of nucleotides was higher than that in the control group.The TML in intestine of fish fed diet with 150 mg/kg of nucleotides was higher than that in the control group.There was no significant difference in fold height(HF)of intestines among all groups(P>0.05).In conclusion, dietary nucleotides can improve the growth of the large yellow croaker.Meanwhile, it can also increase the anti-oxidative capacity and improve the intestinal morphology.Based on the data of WGR, the broken-line analysis showed that the optimal level of dietary nucleotides was 194.91 mg/kg.

Abstract:This experiment was conducted to evaluate the effects of dietary carbohydrate-to-lipid ratio on growth performance, feed utilization, biochemical indices and phosphoenolpyruvate carboxykinase(PEPCK)gene expression in juvenile obscure puffer, Takifugu obscurus.Six isonitrogenous and isoenergetic diets were formulated with dietary CHO:L ratios of 4.29, 2.79, 1.86, 1.19, 0.73 and 0.42, respectively.Fish(initial weight 11.2±0.5 g)were stocked in triplicate tanks(25 fish per tank)and fed to satiation during a period of 60 days.The results indicated that best specific growth rate, protein efficiency ratio and feed efficiency were found in fish fed diet with CHO:L of 1.86, which were significantly higher than those of fish fed diets with 0.42, 0.73 and 4.29(P<0.05).Plasma triglyceride and liver lipid content increased significantly as dietary CHO:L ratio decreasing(P<0.05), while plasma glucose and hepatic glycogen content showed a contrary tendency.Activities of lipase, fatty acid synthase, amylase and pyruvate kinase in liver were significantly affected by dietary CHO:L ratio(P<0.05).Fish fed diets with CHO:L of 0.42 and 0.73 had significantly higher PEPCK activity and mRNA relative expression than those fed with the other diets(P<0.05).However, survival and plasma total cholesterol content were unaffected by dietary CHO:L ratio.The optimal range of CHO:L within 2.01-2.16 is suitable for juvenile obscure puffer based on second-order polynomial regression analysis of SGR, PER and FE against dietary CHO:L ratio, respectively.

Abstract:Sterol regulatory element binding proteins(SREBPs)are nuclear transcription factors critical for regulating the expression of genes related to glucose and lipid metabolism.In order to investigate the molecular regulatory mechanisms of lipid metabolism and liver lipid accumulation in fish, the partial cDNA sequence of sterol regulatory element binding protein 1(SREBP-1)from grass carp has been identified by homology cloning and rapid amplification cDNA ends(RACE), and the structural features of the gene and its encoded protein have been analysed by bioinformatics methods.Using the method of real-time PCR, the expression pattern of SREBP-1 in eight different tissues of grass carp has been studied, and the expression levels of SREBP-1 in liver of grass carp under different feeding conditions with low-carbohydrates(carbohydrates content 24%)and high carbohydrates(carbohydrates content of 42%)have been studied.The result revealed that the obtained cDNA of SREBP-1 in grass carp is 4 760 bp in length, which consisted of a 3 426 bp open reading frame(ORF), encoding 1 141 amino acids.The amino acid sequence has a typical basic helix-loop-helix leucine zipper(bHLH-zip).Alignment based on amino acid sequence showed that grass carp SREBP-1 had a homology of 76%-88% to its counterparts of other fishes.Phylogenetic analysis showed that grass carp SREBP-1 clustered with that of zebrafish.The SREBP-1 mRNA could be detected in all the examined tissues of grass carp.But the expression level in brain was the highest, followed by liver and intestines, and with a little expression in the kidney, spleen, muscle, fat and gonad tissues.Compared with the control, the expression level of SREBP-1 in high carbohydrates(42%)induced group increased significantly(P<0.05).The results showed that SREBP-1 gene may promote the utilization and in version of carbohydrates in grass carp under high carbohydrates loading conditions, which suggested that it may improve the utilization of carbohydrates in grass carp and be involved in its carbohydrates metabolism process.The research data can enrich the glucose metabolism regulation mechanism of fish, and are expected to provide a theoretical basis for improving the utilization efficiency of sugar in fish feed.

Abstract:An unknown disease causing 100% mortality occurred in a koi(Cyprinus carpio)population cultured in Guangdong Province, in April 2013.The moribund koi showed lethargy and unusual swimming behavior such as floating on the pond surface until death.The diseased koi had a mean body length of 25 cm with typical clinical signs including enophthalmia(sunken eyes)and haemorrhages on the skin and base of the fins, and fin erosion.The postmortem examination revealed that liver, spleen, kidney were obviously swollen.No pathogenic bacterium was isolated from internal organs.Positive results were obtained from all detected koi according to a standard PCR diagnosis of CyHV-3 proposed by Office International des Epizooties(OIE).Comparative analysis of nucleotide sequences was performed with the GenBank databases using Blast database network service.The results showed that the putative gene products from infected koi shared 99% identity to that of reported KHV.After filtration treatment, the tissue suspension was injected intraperitoneally into 20 koi.Similar signs appeared and all koi died within 7 days post-infection(p.i.).After filtration treatment, the gills and kidney tissue suspension was inoculated to the CCB monolayer cells.The stable cytopathic effect(CPE)was formed after five blind passages in CCB cells, characterized by severe vacuolation in the infected CCB cells.Under electron microscope(EM), icosahedral viral particles were observed in the cell.The virus particles had an average diameter of 100 nm, and the shape was highly similar to that of KHV.After indirect immunofluorescent antibody test(IFAT), specific fluorescence could be observed on the cell.Based on neighbor-joining analyses of the TK gene sequences, phylogenetic tree was constructed and the result indicated that the pathogen in our study was Asian genotype isolate which was named tentatively KHV-GZ1301.The present study provided important material for virus genesis, evolution, classification, and disease control.

Abstract:This study was designed to explore the anti-WSSV influences of PHB in Chinese shrimp to provide a theoretical basis for the use of PHB in the aquaculture industry.This study used the single factor concentration gradient method.Fenneropenaeus chinensis were artificially infected with WSSV.The F.chinensis were also fed bait that contained different concentrations of PHB(0.0%, 0.5%, 1.0%, 2.5%, 5.0% and 10.0%);these concentrations were adjusted based on the weights of the shrimp at the beginning of the day and the number of shrimp in the tank.During the experimental period, the dead shrimp were collected and stored at -20 ℃, and the time of death and water temperatures were recorded.After the experiment, some of the shrimp were selected based on the death curve, and DNA was extracted.The shrimp survival rates for each treatment were determined daily, and the treatments were compared at each time point in terms of mean survival time, survival rates and relative percent survival(RPS)rates.Moreover, the absolute WSSV loads among the dead shrimp were determined by real-time PCR.The results indicated that the PHB influenced the survival rates, mean survival time and WSSV loads in the shrimp.Compared with the control group, the survival rates and mean survival time of the experimental groups exhibited downward trends following initial increases as the concentrations of PHB increased.The mean survival time of the groups treated with 0.0%, 0.5%, 1.0%, 2.5%, 5.0% and 10.0% PHB were 82.23, 90.71, 95.55, 91.15, 85.56 and 79.40 h, respectively.There were no significant differences in the mean survival time among the shrimp that were supplied with feed containing the 0.5%, 1% and 2.5% concentrations of PHB(P>0.05), but the mean survival time of the other groups were all significantly lower than that of the 1.0% PHB group(P<0.05).The mortality rates for all groups were ultimately 100%.Compared to the control group, the survival rates of the experimental groups were higher and the WSSV loads were lower in the groups in which the PHB concentration did not exceed 2.5% at the same time points.However, similar results were not observed at PHB concentrations above 2.5%.The mean RPS rates of each group were 0.0, 0.364 6, 0.509 4, 0.411 6, -0.150 9 and 0.144 2.There was a significant difference in the RPS rates of the control and 1.0% PHB group(P<0.05).The RPS of the 1.0% PHB group was the highest.When the quantity of WSSV reached the threshold to cause death, the shrimp began to die.During the experimental period, the numbers of WSSV copies for each group were 1.08×10⁷, 1.15×10⁷, 4.75×10⁷, 1.27×10⁷, 1.14×10⁷ and 3.29×10⁶ copies/ng DNA.There was a significant difference between the group that was supplied with 1.0% PHB and the control group(P<0.05).We also found that the numbers of WSSV copies in the 1.0% PHB treatment group were lower than those of the control group in the first 72 h(P<0.05), but higher 72 h later(P<0.05).These results indicated that PHB enhanced the immunity to and tolerance of WSSV in shrimp.This study also revealed that high concentrations of PHB inhibited shrimp survival.The present study found that 1% PHB in the feed was the preferable concentration for improving the ability of shrimp to resist WSSV.

Abstract:Prophenoloxidase-activating factor(PPAF)plays a key role in prophenoloxidase activation system of crustacean's humoral immune system.In this study, the full-length cDNA sequence was cloned by reverse transcriptase polymerase chain reaction(RT-PCR)and rapid-amplification of cDNA ends(RACE), the expression patterns of PPAF gene in various tissues of normal shrimp and IHHNV-infected shrimp were determined by Quantitative real-time PCR.The results showed that the full-length cDNA sequence of PPAF was 1 986 bp, which contained a 21 bp 5'-UTR(untranslated region), 336 bp 3'-UTR(untranslated region), and the 1 629 bp open reading frame(ORF)encoded 542 amino acid.There was a serine protease domain between 269-517 amino acids residues of Litopenaeus vannamei PPAF, an ALPHA-2 macroglobulin functional site and a histamine enzyme active site were found within the 494-502 and 316-321 amino acids residues of Litopenaeus vannamei PPAF respectively.The expression of the gene in various tissues was analyzed by Real-time quantitative PCR, the result showed that the expression of the gene was higher in blood and gill than in heart, hepatopancreas, intestines, stomach and muscle of the normal shrimp or IHHNV-infected shrimp, but the expression of PPAF in various tissues of IHHNV-infected shrimp was lower than in same tissues of normal shrimp.The expression of PPAF in gill of Litopenaeus vannamei drastically reduced after infected with IHHNV, the expression levels reached a minimum within 3 hours, which was about 1/8 times as compared to the control group.After 3 hours shrimp infected with IHHNV, the expression of PPAF in gill increased gradually, and up to highest level after 48 hours.The results suggested IHHNV can protect them from the immunity of Prophenoloxidase by decreasing the expression of PPAF of shrimp when they infect shrimp.

Abstract:Rainbow trout, Oncorhynchus mykiss, is one of the cold water fishes cultured in our country, and the intensification of culture of rainbow trout led to outbreak of several diseases which made the immune system study a new research field.In this study, the truncated heavy chain of IgM was obtained by RT-PCR from rainbow trout head-kidney RNA extracts and cloned into pET-27b vector.The predicted molecular weight of recombinant IgM was approximately 47.7 ku.After purification, the purity of recombinant IgM reached approximately 90% confirmed by SDS-PAGE and HPLC analyses.The rabbit antisera against recombinant truncated IgM in this study could react specifically with both natural IgM from rainbow trout serum and the purified IgM in ELISA test.The titer of rabbit antisera against the recombinant truncated IgM was 1:40 000, the natural IgM was 1:20 000 in an antiserum dose-dependent manner.These results indicated that the recombinant IgM expressed in this study had the comparable structure with the natural IgM of the rainbow trout serum.The results provide important experimental basis for trout immune system study and related immunodetection of rainbow trout.

Abstract:In this paper, a crossing-experiment between Pyropia radi from India and Pyropia haitanenesis from China was done for breeding of improved strains with obvious hybrid recombinant advantages.The male parent was the wild-type strain(Pr-WT01)of P.radi, which was characterized by thick blade, slow growing, good toughness and high production of conchospores, and the female parent was the mutation strain(Ph-HMC5)of P.haitanensis, which was characterized by thin blade, fast growing, poor toughness and low production of conchospores.At first, four improved strains with obvious hybrid recombinant advantages were obtained from the F₁ color-sectored blades, and finally the most improved strain(HR-6)was selected from them.The maximum of absolute growth rate of the male and female parents were 0.39 and 5.24 cm/d, respectively, while that of HR-6 strain was 9.27 cm/d and its absolute growth rate was greater than the maximum growth rate of the female parent during 30-50 days in culture.After 60 days in culture, the mean length of F₁ blades of the male and female parents were 13.18 cm and 85.67 cm, respectively, while that of HR-6 strain was 218.57 cm which was 2.55 times that of the female parent and 16.58 times that of the male parent, respectively.The contents of Chl.a in the 35-day-old blades of HR-6 strain was 9.43 mg/g, increasing by 50% and 20% in contrast with that of the male parent and the female parent, respectively.The content of phycobiliprotein of HR-6 strain was 99.62 mg/g, which was 1.74 times that of the female parent and 2.18 times that of the male parent, respectively.The mean thickness of the 35-day-old blades of HR-6 strain was 26.22 μm, decreasing by 37% in contrast with that of the male parent and increasing by 30% in contrast with that of the female parent, and the toughness of the F₁ blades of HR-6 strain increased significantly.The total number of conchospores released from HR-6 strain was 167.72×10⁴, which was 2.65 times that of the female parent and 1.13 times that of the male parent, respectively.The above results confirmed that HR-6 was characterized by fast growth, high quality, large amount of conchospores, having excellent production applicability.

Abstract:Nile tilapia(Oreochromis niloticus)is one of the lean fish species, and has been known to be a preferable raw material in seafood processing field.As an oxidant, ozone has been gradually used as an antimicrobial additive for direct contact with foods, but there are no special regulation and labelling rules in some countries and regions to date.It is necessary to evaluate the safety of Nile tilapia fillets treated by ozone-water.In this paper, an acute oral toxicity test in SD rats and genetic toxicity test in KM mice were used to evaluate the acute toxicity and the genetic toxicity of Nile tilapia fillets.The results showed that the maximum tolerated dose in SD rats was more than 15 g/kg, the maximum value for cfu of bacterial reverse mutation of TA97, TA98, TA100 and TA102 strains in the 5 dose groups was 156±10 that is less than 2 times of the minimum value for cfu of bacterial reverse mutation of TA97, TA98, TA100 and TA102 strains in positive control groups(1 773±83), with or without S9 metabolic activation system, as well as the repeated assay.Therefore, the result of Ames assay was negative.The micronucleus rates of high, middle and low dose groups were(0.40‰±0.88‰)(♀)/0.40‰±0.83‰)(♂), (0.60‰±0.89‰)(♀)/0.80‰±1.29‰)(♂)and(0.80‰±1.09‰)(♀)/(0.60‰±0.89‰)(♂)respectively.Moreover, the micronucleus rates of control group are(1.20‰±1.29‰)(♀)/(0.40‰±0.89‰)(♂).The results of bone marrow micronucleus test showed that there was no significant difference between the three dose groups and control group(P>0.05).The results of chromosome aberration test showed that chromosome aberration rates of mouse tests were 0.2%, 0.2% and 0.1% respectively, and there was no significant difference between the three dose groups and control group(P>0.05).The results of chromosome aberration test were negative.The research results showed that all of the Ames assay, bone marrow micronucleus test and chromosome aberration test were negative, there was no genetic toxicity of the tilapia fillets treated 30 min by 4.5 g/mL ozone-water which belonged to non-toxic class.

Abstract:Portunus trituberculatus is an economically important marine crab distributed along the coast waters of China, Japan, Korea and Malaysia Islands.In recent decades, the wild population has been constantly decreased due to overfishing and habitats destruction.To protect and recover the P.trituberculatus resources, a large scale of stock enhancement has been carried out in the coastal waters of China.As the stock enhancement activities may change the genetic variability and genetic composition of the recipient wild populations, it is necessary to carry out genetic monitoring of broodstocks and their offspring for the long-term sustainability of wild populations.In present study, genetic diversity and population structure of 4 P.trituberculatus broodstock populations used in stock enhancement were detected according to the sequence of mitochondrial control region.155 mtDNA haplotypes were observed in 301 P.trituberculatus individuals, among which only 20 haplotypes were shared by different populations.The gene diversity index ranged from 0.972 3 to 0.993 0, while the nucleotide diversity index ranged from 0.021 2 to 0.023 6, both of them showed a high level of genetic diversity for broodstock populations.The result of AMOVA suggested that 98.70% of the genetic differentiation occurred within populations.The F_st values between populations ranged from -0.002 5 to 0.023 0, which indicated a little genetic differentiation and no significant genealogical structure among 4 populations together with the result of AMOVA.And no pedigree branch corresponding to different populations was observed in the neighbor-joining tree.The results above suggested that wild populations from where the broodstocks were collected had little genetic differentiation between each other.To sum up, each of the 4 broodstock populations had abundant genetic diversity and similar genetic structure with the wild populations to be supplemented, which reflected good quality of the germplasm resource.The mismatch distribution of pairwise nucleotide and the negatively selective neutrality test suggested that P.trituberculatus of the south Bohai Sea and north Yellow Sea had experienced demographic or spatial expansion in history.

Abstract:Fishing effort is the effort invested in fishery by the same operating method within a period of time.The traditional expression for fishing effort of trawlers is in time and power or tonnage and time.There are 40 thousand vessels installed with terminals of Beidou Satellite Navigation System in China.The vessel position information has a temporal resolution of 3 minutes and a spatial resolution of 10 meters, from which fishing effort can also be extracted.Computation for traditional fishing effort statistics takes much time and effort, and the fishing intensity in macro dimension cannot be accessed in real time.By mining the data from the Beidou satellite ship position monitoring system, such as the position, course, speed and other information of fishing boat, the fishing effort might be explored.In this paper, the speed thresholds of every fishing boat which reflect their fishing condition are obtained by the statistics of vessel speed under steam and trawling.And fishing state points can be judged by combining the speed threshold and heading deviation.The fishing state of trawler 300791 has heading difference and speed thresholds.Minimum and maximum thresholds of heading difference are -50 and 52°.Minimum and maximum thresholds of speed is 0.9 and 2.0 m/s.Via the correction of the filtering window, the fishing area grid is calculated by the accumulated fishing time in fishing state point of each boat.The fishing effort is the product of the accumulated fishing time and the fishing boat power, such as kW·h.And the lattice figure and interpolation of the accumulated fishing are made.This method has the characteristics of real-time, large-scale, fast speed and high resolution, which can provide good reference for the protection of fishery resources.

Abstract:To understand the seasonal variation in the shrimp communities, temporal changes in species composition and community structure of the shrimp community in the Lvsi fishing ground were examined based on data from bottom trawl surveys during spring and summer of 2010.The result indicated that a total of 18 shrimp species were identified, among which 11 were identified in spring and 15 were identified in summer.In spring, it was mainly composed of warm temperate species.Palaemon gravieri was the dominant species in spring, accounting for 52.76% and 64.03% in the individual density and weight density, respectively, while Alpheus juponicus and Alpheus distinguendus were common species.Most of them were warm temperature adapted.In summer, the sea water temperature began to increase, in the meantime, a large quantity of freshwater was found in the area, as a result of the influence of the rainy season and the Yangtse River diluted water.Consequently, shrimp communities showed an obvious succession(R=56%), and warm water species became numerically dominant, for example, Parapenaeopsis hardwickii and Solenocera crassicornis were predominant species in summer, and most of the species belonged to the Indo-West-Pacific warm water region.The warm-temperate species, however, were distinctively decreased during summer.In short, shrimp ecological groups' change in the Lvsi fishing ground during the spring and summer is related with seasonal and hydrological changes.