Abstract:Due to the patchy spatial distribution of marine biota, data collected from bottom trawlers exhibit a skewed distribution with many zero catches and some very large catches. A common problem in the analyses and interpretation of skewed survey data is that, a single immense catch may account for 50% or more of the total catch during the survey. These extreme values not only greatly affect the estimate of the means but also of the variance. Based on the data collected from the bottom trawl survey conducted in the East China Sea, we estimated the average stock density of Todarodes pacificus in summer 2005, Engraulis japonicus in spring 2007, and Trachurus japonicus in autumn 2008 by employing two methods, namely the Δ-distribution method and the design-based method. The results revealed that the estimators of the means and the standard errors of stock density for the three populations based on the Δ-distribution were obviously lower than those based on the design based method. It was concluded that the mean and the standard error would be overestimated using the design-based method. The Δ-distribution was more reasonable when the survey data follow lognormal distribution. Therefore,Δ-distribution is a robust estimating method and is suggested to be widely usable in further studies.

Abstract:Pseudosciaena polyactis and Setipinna taty are two kinds of important commercial fish species in the northern East China Sea and the Bohai Sea, and they play an important role in the marine ecosystems. In our study, the dietary overlap and food competition between these two juvenile fish species at their common length of 35~69 mm were examined by applying the multivariate statistical technique, the Schoener’s similarity index, and the Pianka index, based on the total of 547 samples collected from seasonal bottom trawl surveys in the Haizhou Bay of the Yellow Sea during July~August, 2008. The results indicated that these two juvenile fish species had the same trophic level of 3.33. Both the Schoener’s similarity index (0.06~0.20) and dietary overlap coefficient (0.03~0.38) between juveniles of the two fish species were lower than 0.6. In contrast, their intra-specific values of food composition similarity and dietary overlap coefficient were relatively high. At the species level, crustaceans including Labidocera euchaeta and Acanthomysis longirostris were the common preys in the developing prophase of the two fish species. Then different changes in diet appeared as the two juvenile fish grew. We conclude that there is low inter-specific competition between juveniles of these two fish species and high intra-specific competition within each species.

Abstract:Total RNA was extracted from the pituitary gland of half-smooth tongue sole Cynoglossus semilaevis Günther, and the follicle stimulating hormone (FSH) was cloned by using RT-PCR and RACE technology for the first time. The cDNA of FSH is 541bp, and the open reading frame was 393bp encoding peptides of 130 amino acids. This cDNA sequence was submitted to GenBank with Accession No. JQ277933. One N-glycosylation site was found in the deduced amino acid sequence. Multiple amino acid sequences alignments were performed among vertebrates including Osteichthyes, Amphibia, Reptilia, Aves and Mammalia. It showed that half-smooth tongue sole FSH mature peptide was more similar to their orthologs of Pleuronectiformes and Perciformes which was 42%-49% identity than to Cypriniformes and mammalian which was 27%-31% identity. The pairwise distances were computed and phylogenetic trees were constructed using NJ method based on the codon sequences of the chosen species by MEGA 4.0 software. The result indicated that the FSH of half-smooth tongue sole was clustered together with other fish FSH, and the half-smooth tongue sole gene shared high homology with teleost. Real-time PCR analysis showed that FSH mRNA was expressed at the highest level in pituitary. Also strong amplification signals were detected in all other tissues, especially brain and gonad. FSH mRNA of half-smooth tongue sole expressed widely in non-pituitary tissues may indicate that it has more physiological functions.

Abstract:The effect of starvation for varied period of time and subsequent feeding for the same time on the biochemical composition and energy value of Platichthys stellatus, cultured in seawater at salinity of 32±1 and temperature of 19±1 ℃, was examined. The contents of water, lipid, protein, and ash in the body and feces of P.stellatus at an average body weight of 26.02±0.30g were determined. Compared to the control group, the contents of the examined items were significantly different in three treatments which were starved for 5, 10, and 15 days respectively and subjected to subsequent re-feeding. The contents of water, lipid, and ash, and the energy value in the body of P. stellatus changed significantly, while the content of protein showed a moderate change. The contents of lipid and protein in the feces changed noticeably while the content of ash and the energy value stayed unchanged compared to the control group. It was also found that the biochemical composition was positively correlated with the time of starvation; the longer the starvation time, the more significant the change. The biochemical composition gradually recovered to the normal values after re-feeding, and the longer the starvation time, the longer the recovery time.

Abstract:A digestive experiment was conducted on Japanese sea bass Lateolabrax japonicus weighing 30±2.3g at 23±2℃. Chromic oxide (Cr2O3) was used as the inert indicator. The apparent digestibility of dry matter, protein, lipid, energy, and amino acids in seven feed ingredients (white meal, blood meal, shrimp meal, feather meal, double low rapeseed meal, high gluten flour, and rice bran) were determined. The test diets were composed of 70% reference diet and 30% test ingredient. The results showed that the apparent digestibility of dry matter was in the range of 98.71%~41.84%, among which the fish meal (98.71%) was the highest compared to the others. Digestible protein from these ingredients was in the range of 45.01%~86.86%,comparatively, above 98% for fish meal and rice bran. The assimilation of energy was the highest in the fish meal (95.24%) and the lowest in the shrimp meal (65.54%). The liver histology has been affected by the diets containing blood meal, feather meal, double low rapeseed meal, high gluten flour, and rice bran after 70 days experiment. The lesions occurred, including fatty degeneration and leukocyte of infiltration in the hepatic tissue, and aquatic degeneration, etc. With blood meal, feather meal, and double low rapeseed meal replacements, pathological disruption of intestine was observed, characterized by sloughing of epithelium cell and increasing amounts of leukocytes in it.

Abstract:One potential probiotic bacterium TYTG1 screened from the intestine of cultured Scophthalmus maximus was obtained. The antagonism of bacterium TYTG1 to turbot pathogens Vibrio archariae and V. scophthalmi was evaluated. Based on the morphological observations, physiological and biochemical characteristics and 16S rDNA sequence analysis, the bacterium was identified as Bacillus subtilis. This is the first report on B. subtilis being found in the intestine of cultured S. maximus in China. The TYTG1 is a eurythermal bacterium that can grow at 4~42 ℃. S. maximus could grow without any abnormal phenomenon as they were fed with the TYTG1 bacterial cells at densities of 107 or 109 CFU/g for 4 weeks. The bacterium exhibited an excellent antagonism to the pathogens V. archariae and V. scophthalmi which could cause ascetic and enteric diseases in turbots. Therefore this probiotic bacterium is a potential candidate to be applied in turbot culture.

Abstract:Aquareoviruses, which belong to a newly identified genus of the family Reoviridae, are agents infecting all kinds of aquatic animals. Grass carp reovirus (GCRV) is a kind of pathogenic virus which causes disease outbreak of Grass carp fingerling in freshwater region of China. In June 2008, a strain virus had been isolated from the samples of visceral organs of the diseased Grass carp with Hemorrhage symptoms from a fish pond at Huzhou City in Zhejiang Province. Sample of diseased Grass carp visceral organs was filtered and was injected into healthy Grass carp fingerlings. Clinical signs of Hemorrhage symptoms of Grass Carp were replicated after five days. Mortality of the sample was 57%. By contrast, the control group fishes were still alive. The sample was continually inoculated onto CIK cells and induced typical cytopathic effect (CPE) was observed. The typical CPE was the same with that induced by the GCRV873 strain. The TCID50 of the isolated virus strain was 108/0.1ml. The visceral organs examined by electron microscopy showed that there were a number of viral particles approximately 71~75 nm in diameter with a sphericity shape. Physicochemically, the isolated strain was not sensitive to chloroform and ether. 436bp nucleotide segment was amplified from the isolated virus strain by reverse transcription polymerase chain reaction (RT-PCR). The nucleic acid sequence of the amplicon had been sequenced. It showed 99% identity with those of GCRV strains in GenBank. All of the evidences indicated that the isolated virus stain was GCRV and was named as HZ2008 isolate.

Abstract:Under indoor simulation conditions, the effects of various concentrations and exposure time of Shengli crude oil on the activities of superoxide dismutase (SOD) and catalase (CAT) in the liver of juvenile Cynoglossus semilaevis were studied. The change of SOD and CAT activities versus time showed an increase-decrease-increase trend, and the time for SOD activities to reach the peak value was shorter when exposed to the higher concentrations. In terms of the dose-effect relationship, the activities of SOD and CAT were induced by oil treatment at the lower concentrations and were suppressed at the higher concentrations. A threshold of toxic effects of the oil on the organism was observed, below which there was no toxicity, and the activities of SOD and CAT recovered to the normal level quickly after being released from the pollution stress. In this study, the threshold for CAT was in the range of 0.2~0.4 mg/L, and 1.6~3.2 mg/L for SOD. Beyond the threshold value, the rate of active oxygen production induced by the petroleum pollutant overtook the anti-oxidation eliminating activity of the defense system of the organism, incurring damage to the poisoned organism. The response of CAT activity to the petroleum pollutant was more sensitive than SOD, indicating that CAT can better reflect pollution stress and can be a bio-indicator candidate for petroleum pollution.

Abstract:The effects of pH stress on non-specific immune factors and the RNA/DNA ratio of Marsupenaeus japonicus were investigated. It was found that the activity of total nitric oxide synthase (TNOS) in M. japonicus of low pH group (pH 7.2) and high pH group (pH 9.2) reached the maximum at 3h and 12h, respectively. The activity of inducible nitric oxide synthase (INOS) in pH stress groups reached the maximum at 3h, then gradually declined and stabilized at 72h. The activity changes of phenoloxidase (PO) in M. japonicus under both the low and high pH conditions showed that they reached the peak value at 12h, gradually decreased thereafter, and became stable after 72h. Activities of lysozyme, superoxide dismutase, and glutathione peroxidase in M. japonicus decreased gradually under pH stress. The changes of non-specific immune enzymatic activity showed that the immune adaptive activity in M. japonicus exposed to the high pH stress was lower than those exposed to the low pH stress. Moreover, the RNA/DNA ratio in the muscle of M. japonicus under the pH stress conditions was significantly lower than that of the control group, supposedly due to the effects of pH stress on metabolism of M. japonicus.

Abstract:The nitrification and denitrification rates in the sediments of the feeding and non-feeding areas of the shrimp culture pond were measured by applying acetylene inhibition technique, and the N2O concentration in the surface water was determined by GC-ECD during July~August, 2009. The results showed that the rates of nitrification, denitrification, and nitrate reduction ranged between 10.70～337.47 μmol/m2·h, 1.10～17.92 μmol/m2·h, 0.09～7.48 mmol/m2·h respectively. Concentrations of N2O in the surface water was 5.98～10.9 nmol/L and the air-water flux of N2O ranged between 1.76～3.89 μmol/m2·d. Nitrification and denitrification process in the sediments of the shrimp pond showed both significant regional differences and significant seasonal variations. In mid-August, nitrification and denitrification rates reached the highest values, and in the whole culture period, nitrification rates in the feeding area were 2~10 folds of the non-feeding area, and denitrification rates in the feeding area were 1~4 folds of the non feeding area. Denitrification played an important role in the nitrogen cycle of the shrimp pond ecosystem, removing inorganic nitrogen at 2.80 g/d, accounting for 2.34% of the total input of inorganic nitrogen and 2.56% of the total output in the shrimp pond.

Abstract:The fertilization biology characteristics of eggs and sperms in two scallop species, Patinopecten yessoensis and Chlamys farreri, including morphological changes of gametes after release, egg water characteristics, sperm acrosome reaction, egg cortical reaction, and the effect of the sperm fractional separation components on the eggs, were observed using electronic microscopy, optical microscopy, and spectrum scanning analysis and insemination. The results showed that there were no significant difference in biological characteristics between P. yessoensis and C. farreri. No obvious appearance changes in the scallop sperms within 10min after release in the seawater. However, 30 minutes later, 25% of the sperms became head-enlarged to near spherical and the fertilization ability was weakened. While the fertilization ability of the scallop eggs did not change within 1 hour after release in the seawater, and about 33% of the eggs became cleaved but without appearance of polar body in two hours. Most egg cleavage were equal cleavage terminated at the 2-cell stage and some at the 4-cell stage, and the fertilization ability of the eggs at this phase were lost. Most sperms dropped into the egg water were autolyzed, and other sperm agglutinated. No intact sperm individual was seen after being transferred into the egg water for 10 minutes. The sperm acrosome reaction was induced by the egg water or calcium ionophone A23187.Although a few sperm heads attached to the surface of the eggs, the components of sperm including seminal plasma, sperm head, and sperm tail, could not activate the eggs. This research on biological characteristics of eggs and sperms in scallop are expected to provide basic data for understanding why sperm and eggs from different species of scallops could recognize each other and fertilize.

Abstract:According to the gene sequence of Perkinsus sp. in GenBank, one pair of specific primers were designed to amplify the specific fragments of Perkinsus sp. in shellfish. The obtained 596bp PCR product shared 99.8 % identity with the published sequence. This PCR assay was specific and no PCR product was detected from other pathogenic bacteria such as Pseudomonas fluorescens, Aeromonas hydrophila, Escherichia coli, Staphylococcus, Vibrio parahaemolyticus, Salmonella, and Norwalk virus. The sensitivity determination showed that the lowest amount of Perkinsus sp. detected by this PCR was 1pg DNA. In our study, 104 Oyster, 49 Mussel, and 20 Clam samples collected from Guangxi coasts were tested by this PCR method. The percentage of positive results were 14.6%, 10.6%, and 15.0% respectively, suggesting that Perkinsus sp. exists widely in the cultivated shellfish in southern China and this PCR assay is a sensitive tool to detect Perkinsus sp. in clinical samples.

Abstract:During late April to early June, 2009, free-floating green algae broke out in some inner bays of Qingdao. We investigated the coastal areas with green algae and found that the estimated biomass of Ulva blooms in Qingdao Bay reached 138 t at its peak time. Through morphological and microscopic examinations, the green algae samples were preliminarily indentified as Ulva linza, though they possessed wider and longer thalli and thickened cell walls compared to the immobilized Ulva linza. PCR amplification and phylogenetic analysis of the 18S-28S rDNA internal transcribed spacer (ITS) and 5S rDNA spacer region (5SS) of the free-floating samples confirmed that the free-floating algae was Ulva linza. Morphological changes could help free-floating Ulva linza adapt to the new drifting life. This is the first time that the Ulva linza blooms in inner bays of Qingdao was reported.

Abstract:The variations of endogenous hormones in different periods and different parts of Rongfu Laminaria saccharia were analyzed by high performance liquid chromatography coupled with UV detector. It was found that the content of indole-3-acetic acid (IAA) and abscisic acid (ABA) increased significantly in three important periods of L. japonica (juvenile,grow-out,mature). The content of zeatin (ZT) reached the highest in the mature period,and the lowest in the grow-out period. The content of indolebutyric acid (IBA) reached the highest in the grow-out period,and the lowest in the juvenile period. At each development stage,different plant hormones were found at the highest contents in different parts of the L. saccharia blade; IAA showed the highest content in the top,while the highest contents of ZT was found in the middle,and both IBA and ABA were found in the bottom.

Abstract:Research on the influence of heavy metals and other environmental pollutants on the antioxidant defense system has become one of the hotspots of ecological toxicology in recent years. Effects of three heavy metal ions, Hg(Ⅱ), Pb(Ⅱ), and Cd(Ⅱ) on the activity of total superoxide dismutase (T-SOD) in the tissue of Calanus sinicus were examined through outside body sublethal toxicity testing. The results showed that the T-SOD activity changed markedly under prolonged exposure to these ions. The activity of T-SOD reached the maximum at 12 hours, when Hg(Ⅱ) concentrations were 0.001 3~0.005 3 mg/L. When the concentrations of Pb(Ⅱ) were 0.468 0, 0.936 0, and 1.872 0 mg/L, the activity of T-SOD reached the maximum at 36 h, 24 h, and 12 h, respectively. Effects of Hg(Ⅱ) and Pb(Ⅱ) on the SOD activity increased first and then decreased during the prolonged exposure. The activities of SOD underwent a course of increase-decrease-increase-decrease in the presence of Cd(Ⅱ). At all the three concentrations of Cd(Ⅱ), the activity of T-SOD reached the maximum at 12 hours.

Abstract:Lipopolysaccharides (LPS) were extracted from ten Vibrio alginolyticus strains with different virulence. Five of them were virulent strains, named as HN08811, HN08155, HN08813, HN08335, and HN07006 and the others were non-virulent strains, named as HN08805, HN08307, HN08232, HN08201, and TG06003. The results of SDS-PAGE (sodium dodecyl sulfate polyacrylamide polyacrylamide gel electrophoresis) with 10 μg LPS showed that LPS of V. alginolyticus strains with different virulence had abundant polymorphism. The polymorphism of lipid A section of each LPS was difficult to distinguish. However, for the O-antigen section, 7~8 clear bands of LPSs from virulent strains were observed except for HN07006. LPSs from all the non-virulent strains had discernable slender and intensive bands. This method not only creates a new molecular typing method for rapid identification of virulent strains of V. alginolyticus, but also provides scientific theoretical data for the analysis of serotype of V. alginolyticus.

Abstract:The sobering-up effects of components in oyster meat such as protein, glycogen, and taurine were investigated by determining the concentration of alcohol in the serum of the mice with oral alcohol intake. The male mice were randomly divided into three groups (n=10) treated respectively with protein, glycogen, and taurine, and a control group. Oyster protein, glycogen, and taurine were given to the mice 30 min before feeding a dose of alcohol. The alcohol levels in the serum of the mice were then measured 60 min later. The results showed that, compared to the control group, protein in oyster meat had no obvious sobering-up effect, while glycogen at 0.8 mg/ml and taurine at 0.05 mg/ml reduced the alcohol concentration in the mice serum by 49.41% and 43.74% respectively, indicating that glycogen and taurine are the major sobering-up substances in oyster meat.

Abstract:A study was conducted to investigate the effects of dietary zinc levels on growth,blood physiological and biochemical indices and antioxidant ability of juvenile starry flounder -Platichthys stellatus-.Basal diet was prepared using casein-gelatin as the protein source.Zinc (ZnSO4 ·7H2O) was added at graded levels (0,50,100,150,200,and 400 mg/kg diet) to basal diets to formulate six isonitrogenous and isoenergetic purified diets.Triplicate of six treatment groups of juvenile starry flounder (initial weight,62.89±0.51 g) were fed to apparent satiation for 66 d.The results showed that the weight gain rate (WGR ) increased significantly when juvenile starry flounder were fed the diets with 150～400 mg/kg of dietary supplemental zinc (P<0.05).The highest WGR and the lowest feed conversion rate (FCR ) were observed in treatments with 150 mg/kg of dietary supplemental zinc.The number of erythrocytes was significantly higher than the control group when the juveniles were fed the diets with 100～200 mg/kg of dietary supplemental zinc (P<0.05),and the hematocrit and hemoglobin of the control group fed basal diets without zinc were significantly lower than those of other groups with zinc treatment (P<0.05).Contents of serum protein in groups treated with all levels of zinc were comparatively similar (P>0.05).Activity of serum lysozyme (LSZ) in juvenile starry flounder increased significantly with the increasing level of dietary supplemental zinc (P<0.05),but no significant differences were observed among the juveniles fed the diets with equal to or higher than 150 mg/kg of dietary supplemental zinc (P>0.05).The LSZ activity peaked in the treatment with 150 mg/kg of dietary supplemental zinc.Activity of serum CuZn superoxide dismutase (CuZn-SOD) in 0 and 50 mg/kg zinc treatment were significantly lower than those in other groups (P<0.05).The contents of malondialdehyde (MDA) in muscle of juveniles fed with 0 and 50 mg/kg zinc were significantly higher than those in other groups (P<0.05),while the minimum level of MDA was in 150 mg/kg zinc fed group.The optimal dose of dietary supplemental zinc in juvenile starry flounder purified diet was suggested to be 150 mg/kg.

Abstract:This study was conducted to determine the effects of several diets on the growth and body composition of sea cucumber Apostichopus japonicus.A.japonicus at 4.18±0.23cm of body length and 5.99±0.26g of body weight were fed with different diets,including animal-based (fish meal) diet,Sargassum thunbergii Kuntze, Enteromorpha prolifera,Laminaria japonica, and sea mud-based diet for 80d.Sea cucumbers were maintained in glass aquaria and fed with the five different diets.The special growth rate of sea cucumbers fed with diets of S.thunbergii,E.prolifera and fishmeal were 95.36%/d-1,92.29%/d-1 and 84.87%/d-1,respectively,which were not significantly different but higher than those fed with diets of L.japonica or sea mud.It was found that,although the animal's utilization of plant protein was higher,it is practically feasible to formulate more wholesome feed by using animal-based protein as the diet ingredient; E.prolifera is an alternative food source for juvenile sea cucumbers; Ground dried L.japonica should not be used as the major ingredient of sea cucumber diets.