Abstract:Based on the samples collected during nine bottom trawl surveys in Laizhou Bay conducted from May 2011 to April 2012, 20 fish species and 4 854 stomach samples were analyzed. Five kinds of feeding habits were found among the fish assemblages in the Laizhou Bay, including zooplankivores, benthivores, piscivores, omnivores and generalist predators. Benthivory is an important feeding habit in fish assemblage in each month, and the benthic prey such as gammarid amphipods and bivalvia, was the primary prey in the food relationship of Laizhou Bay. The composition of feeding type in fish assemblage of late autumn and early spring was simple, and benthivores were the major component, then as water temperature increased, the composition became complicated. The results showed that the food structure of fish assemblage in Laizhou Bay favored growth and survival of the released species. In order to ensure the effect of enhancement and release, it is suggested that the food relationship and prey condition in the waters around the released place should be track-surveyed, and the suitable place and time for release should be selected.

Abstract:Based on the data collected by trawl surveys in June and July of 2010 in Huanghe estuary and its adjacent area, fish community patterns such as species compositions, dominant species, spatial distribution, diversity and similarity were studied. In the investigated area, 37°30′~38°00′N, 119°09′~119°30′E, eight sampling stations were set up. A total number of 32 species were collected in the present study, and all of them were Osteichthyes species, belonging to 32 genera, 21 families and 7 orders. There are 4 groups according to their habitat type, in which 7 species were continental shelf pelagic-neritic fish, 18 species were continental shelf benthopelagic fish, 7 species were continental shelf demersal fish, and 1 was continental shelf reef-associated fish. According to their optimum living temperature, fish species were divided into 3 fish groups, including 9 warm water species, 16 warm temperate species and 7 cold temperate species. There were seven fish groups according to the analysis of feeding habit: 6 species were planktivores, 4 species were planktivores/benthivores, 7 species were benthivores, 5 species were benthivores/piscivores, 1 species was piscivores, 7 species were omnivores and 2 species were detritivores. The index of relative importance (IRI) was calculated to determine the importance of the species. Species were defined as dominant species when IRI value was larger than 1000. There dominant species were Chaeturichthys stigmatias, Cynoglossus joyneri and Acanthogobius ommaturus in June and C. stigmatias, Konosirus punctatus, C. joyneri and A. ommaturus in July. The biomass and abundance of fish increased greatly in survey before WSDR were grouped than those in survey after WSDR. The Margalef richness index (D), Shannon's diversity index (H′) and Pielou's evenness index (J′) of fish community in the survey before WSDR were all higher than those in survey after WSDR. But no significant differences were found in the diversity between the two surveys. Cluster analysis and non-metric multidimensional scaling were used for analyzing fish community structure. The results showed that community structure was obviously different between the two surveys. The 8 stations surveyed before WSDR can be grouped into one group, and the 8 stations surveyed after WSDR were grouped into another group. The dissimilarity was caused mostly by the biomass composition and its spatial distribution of C. stigmatias, K. punctatus, A. ommaturus,Scomberomorus niphonius, Platycephalus indicus and C. joyneri. The similarity of the community in the two surveys was low. The Jaccard's species similarity coefficient was 56.3%, and the Bray-Curtis similarity coefficient was 43.1%. In conclusion, compared with the survey data of 1980s, the numbers of fish species in the Huanghe estuary and adjacent area showed a downward trend, and the biomass distribution of fish in scale of time and dominant species composition changed significantly.

Abstract:In this study, daily food consumption by silver pomfret in the southern waters of the Yellow Sea evaluated by means of the Mercury Mass Balance Model (MMBM) was about 5.87 g wet/100 g wet/d. Based on its biomass estimated through four acoustic survey cruises, the annual food consumption of this stock in the southern waters of the Yellow Sea during 1998~2000 was about 4.78×105 t, and the conversion efficiency was 1.46%. Esophageal sac observation and stomach content analysis revealed that jellyfish was one kind of food sources of silver pomfret. Esophageal sac was essential digestive organ to mill jellyfish, and scales in stomach were not feeding objects. It is suggested that, in order to elucidate whether jellyfish bloom could be controlled by increasing silver pomfret abundance, further research on the characteristics of feeding process of silver pomfret on jellyfish is needed.

Abstract:Mitochondrial COI gene fragments and ribosomal 28S rRNA of Atrina pectinta sampled from five locations including three in Shandong (Changdao, Wendeng, and Rizhao), one Guangdong (Zhanjiang) and one in Hainan (Haikou) were amplified with universal primers, and 623bp and 983bp nucleotide sequences were obtained, respectively. Phylogenetic studies of Pinnidae based on 28S rRNA partial sequences showed that A. pectinta had a close genetic relationship with Atrina vexillumju. Genetic diversity of the five populations based on COI partial sequences demonstrated that the Wendeng population had the highest level of genetic diversity. The fixation indices (Fst) analyzed by AMOVA was 0.132 3 (P<0.001), indicating that the genetic variation of A. pectinta was mainly from genetic fixation inter-populations. Cluster analysis based on 28S rRNA and COI showed that A. pectinta in China might have differentiated into different subspecies. These findings would provide molecular biological data for the protection and utilization of A. pectinta resources in China.

Abstract:Phosphorus is the most important limiting factor in nutrient cycling, and it is also the key element controlling primary production in aquatic environment. Sediments act as both a sink and a source of phosphorus due to continuous transport of chemical species across the sediment-water interface. Phosphorus is actively involved in both terrestrial and marine biogeochemical cycles. However, not all fractions of phosphorus in sediment are released to the overlying water. Therefore, the effects of phosphorus fractions in sediments for promoting aquatic environment eutrophication can be more efficiently evaluated based on phosphorus fractions, rather than total phosphorus. In this work, forms and bioavailability of phosphorus in the columnar sediments of two sampling sites in Sanggou Bay were analyzed by means of sequential extraction method (SEDEX). According to this method, there are five types of phosphorous:iron-phosphorous (Fe-P), organic-phosphorous (Or-P), detritus-phosphorous (De-P), exchangeable-phosphorous (Ex-P) and autologous-phosphorous (Au-P); The ages of sediment were also used to explore the content change of phosphorous forms in about two hundred years.The results showed that, for two sites, the contents of total phosphorus and phosphorus forms in the core sediments obviously decreased with depth.The main form of total phosphorus (TP) in sediments was organic phosphorus (Or-P) ,which accounted for 59.5 %, 57.6 % of TP in S1 and S2 sites, respectively ,and the percentage of Fe-P was less than 1 % ,which indicated that the environment of Sanggou Bay was less polluted. The contents of various forms in upper layer were all higher than those in bottom sediment and varied greatly in the shell deposition, which suggested that farming activity increased phosphorus sedimentation. In addition, the total phosphorus and contents of phosphorus forms had a tendency to decrease toward the bottom of the core, regardless of the phosphorus species;The distribution of TP and Or-P in time series was almost the same for both two sites;Bioavailable phosphorus in sediments occupied 61.2 % ,71.0 % of the total phosphorus pool,respectively;The content of Ex-P in sediment imposed a greater impact on the primary productivity in culture zones of Sanggou Bay.

Abstract:Four hundred and fifty Nibea albiflora juveniles(10.0~10.7g) were randomly distributed in four experimental treatments at different culture densities: 15ind/tank (1.49 kg/m3), 30ind/tank (3.00kg/m3), 45ind/tank (4.84 kg/m3), and 60ind/tank (5.81 kg/m3). A 30-day feeding experiment was conducted to investigate the impact of density stress on growth performance, feed coefficient, plasma complement of C3 and C4, and activity of related enzymes of the fish. Weight gain (WG) did not show significant differences among treatments.The trend of specific growth rate (SGR) was similar to that of WG. Feed conversion rate (FCR) increased with the increasing density. FCR of G60 was the highest and significantly higher than the other treatments (P＜0.05). (2) Activity of lactic dehydrogenase (LDH) in G60 was the highest and significantly higher than other treatments（P＜0.05）. Glutamic pyruvic transaminase (GPT/ALT) activity increased with the increase of density, while there were no significant differences among the treatments (P＞0.05). Similar trend was found in activity of glutamic oxaloacetic transaminase (GOT/AST). (3) The activity of lysozyme in serum decreased with the increase of density. The activity of lysozyme in G60 was the lowest and significantly lower than the other treatments (P＜0.05). Both complement of C3 and C4 in G30 were the highest, but they were not significantly affected by density (P＞0.05). This study indicated that high stocking density may impact metabolism and non-specific immune functions of juvenile N.albiflora, while low stocking density would suffer a great waste of water resource. Thirty individuals per tank（3.00 kg/m3）was considered to be a suitable stocking density.

Abstract:In this study, the specific activity of digestive enzymes of Sebastes schlegeli juvenile subjected to starvation and refeeding was determined at 17.6±0.2℃. The experiment included four treatments, and within each treatment there were three replicates. Treatment A was the control group, which were fed normally during the process of the study. Treatment B experienced 5d food deprivation and 50d refeeding, Treatment C experienced 10d food deprivation and 45d refeeding. Treatment D experienced 15d food deprivation and 40d refeeding. The experimental results showed that the activities of protease and trypsin decreased obviously during the starvation; the activity of lipase went on a downward trend, which was not significant; the activity of amylase increased greatly during the early days of starvation. After refeeding， except protease in intestines and trypsin in liver, activities of all other digestive enzymes returned to the normal level.

Abstract:Effects of two first-feeding diets(rotifers and fertilized oyster eggs) on the early stage larvae of seven-band grouper Epinephelus septemfasciatus were analyzed and compared with three different feeding modes (A. rotifers, B. oyster eggs, C. mixture of oyster eggs and rotifers) under artificial rearing conditions. Through observations on the feeding situation of 5 dph (day-post-hatching) larvae and gastrointestinal fullness of 4~20 dph larvae, the larval feeding habits and the relationship of light and feeding were discussed. We found that treatment B, which was fed with oyster eggs for 3 days,grew much better than treatment A, which was fed with rotifers only.The specific growth rate of total length in treatment B was 4.969%, which was 2.5- and 2.4-fold of treatments A and C, respectively. Before 10dph, total length, anal distance, and mouth width in treatment B were greater than the other two treatments. Two obvious feeding peaks were found at 9∶00~10∶00 and 13∶00~14∶00 for 5 dph larvae. The light intensity was between 720~1,018 lx and 865~923 lx respectively. The satiation rate of 4dph larvae was lower, in which only 40% reached the Ⅲ level in food intake. Satiation rate of 4~10dph larvae fluctuated, and it began to rise at 10dph, reaching 100% at 13dph.

Abstract:Vibrio alginolyticus, V.harveyi and V.parahaemolyticus are main causes of ulcer disease for Pseudosciaena crocea. In this research, we set three experimental treatments of P. crocea which were injected with 0.2ml V. harveyi,V. alginolyticus or V. parahaemolyticus, respectively, while injection of normal saline at the same dose was given to the control.To study the impact of the three pathogenic Vibrios on the P. crocea’s blood biochemical parameters, contents of carbohydrate, lipid, protein, electrolyte and protein metabolism products and enzyme activity in serum were determined and compared by sampling at different time-point for 20d after infection. The results showed that the change of blood biochemical parameters occurred mainly in 1~4d after the Vibrio injection. Contents of TP, ALB, GLOB, ALT, AST, LDH, K,and Fe increased significantly(P<0.05), and contents of blood urea nitrogen, serum creatinine, blood sugar, cholesterol, Na,and Cl decreased significantly(P<0.05), while contents of TG, P, Ca, and Mg did not change significantly (P>0.05).These observations indicated that Vibiro infection has impacts on physiological functions and metabolic levels of P.crocea. The study indicates that the stress reaction to the Vibrios occurred mainly during the early stage after infection, and serum biochemical parameters can be used as early-warning indicators of ulcerous infection for P. crocea.

Abstract:An eight-month feeding experiment was conducted to determine the impact of dietary vitamin C on the reproductive performance of turbot Scophthalmus maximus.The basal diet was supplemented with 0,800 and 4 800 mg/kg vitamin C to formulate three experimental diets.Results showed that the growth of turbot broodstock was improved with the increasing dietary vitamin C, but no significant difference was observed between control and vitamin C supplementation treatments.The egg production of female broodstock fed vitamin C supplemented diets was significantly (P<0.05) higher than those fed the basal diet.The gonadosomatic index (GSI),number of spawns,percentage of buoyant egg,fertilization rate and hatching rate of 800 mg/kg and 4 800 mg/kg treatments were significantly higher with the increase of vitamin C addition in diets(P<0.05). Vitamin C concentrations in eggs reflected dietary vitamin C addition.The egg diameter and oil globule diameter of turbot broodstock was improved with the increasing dietary vitamin C,but no significant difference was observed between control and vitamin C supplementation treatments.With the increase of dietary vitamin C, the activities of superoxide ismutase (SOD) in tissues were significantly reduced (P<0.05),but malonaldehyde (MDA) contents were significantly increased (P<0.05).So,it is concluded that vitamin C supplement in the diets can improve the reproductive performance of turbot broodstock.

Abstract:Vertical polyacrylamide gel electrophoresis was employed to investigate the genetic variation of isozyme of Charybdis japonica. Four geographic populations in Dalian Black Reefs (DL), Shangdong Laizhou Bay (LZ), Jiangsu Haizhou Bay (HZ) and Zhejiang Xiangshan (XS) (48 individuals each) were surveyed. Ten enzymes revealed twenty-eight putative loci, in which nine were polymorphic. For the four populations, the proportion of polymorphic loci (P0.99) was 32.14%. The mean effective number (Ae) of alleles per locus ranged from 1.283 0 to 1.297 9, and the mean values of observed (Ho) and expected (He) heterozygosities were in the range of 0.146 2~0.155 6 and 0.273 8~0.278 3 respectively. The genetic distance (Dnei ) among the four wild geographic populations ranged from 0.000 4 to 0.001 8, which were lower than that between subspecies. Cluster analysis indicated that DL and LZ populations were clustered together for the closest relationship, while HZ or XS, respectively, was an independent cluster.

Abstract:The mRNA expression levels of HSP60 and HSP90 in tissues of gill, intestine, hepatopancreas, muscle, hemocyte and lymphoid were assayed by quantitative real-time PCR. Results showed that HSP60 and HSP90 were expressed in the six tissues. WSSV infection affected the transcription levels of HSPs mRNA. WSSV infection inhibited the expression of HSP60 in the tissues of gill, intestine, muscle and hemocyte, and promoted the expression of HSP90 in the tissues of gill, intestine, hepatopancreas, muscle, hemocyte and lymphoid. This indicated that both HSP60 and HSP90 took part in immune responses.

Abstract:Static method was employed to study feeding behaviors of Japanese scallop Patinopecten yessoensis feeding on different food such as flounder Paralichthys olivaceus feces, residual feed, sediment particulates and microalgae.Clearance rate and ingestion rate on microalgae were significantly higher than the other three experimental groups (ANOVA, P<0.01). Absorption efficiencies (AE) among microalgae, fish feces and residual feed were not significantly different, but they were significantly higher than that on sediment particulates. There was a positive correlation between AE and organic content (f): AE(％)＝38.84lnf+72.7 (R2=0.378); The linear relationship between absorption rate (AR) and particulate organic matter (POM) was described as: AR＝0.118×POM-0.555 (R2=0.329). Total particulate matter (TPM) threshold for pseudo-feces production was 24.09 mg/L, and the scallop could regulate food intake by pseudo-feces production. Based on the research results,the potential Integrated Multi-trophic Aquaculture (IMTA)of shellfish and fish was proposed.

Abstract:The reproductive shoots of Zostera marina L. in different growth state was cultivated in vitro to study the feasibility of harvesting seeds by temporary cultivation of reproductive shoots. The process of flowering, pollination, fruiting, seed germination, seedling development and the anatomical structure of reproductive shoot, mature seed, seed embryo were observed and described. It was found that the structure of reproductive shoots were highly adaptive to the water environment. Their morphological changes were the outstanding feature during flowering. The seeds of Z. marina has special embryo structure with the radicle, plumule and hypocotyl wrapped by the U-shaped cotyledon, which led to a characteristic germination process. These results indicated the feasibility of collecting seeds by cultivating in vitro the reproductive shoots, where no data on phenological characteristics of Z. marina are available.

Abstract:The antibacterial activities of the hydrolysates from Ruditapes philippinarum, prepared by pepsin,acid protease, bromelin, trypsin and papain, were compared. Orthogonal experiments were employed to optimize the preparation process of the hydrolysate with the greatest antibacterial activity, and molecular weight distribution of the optimal hydrolysate was determined. The hydrolysate of pepsin showed antibacterial activity against Staphylococcus aureus,Escherichia coli, Bacillus subtills, Saccharomyces cerevisiae and Vibrio parahaemolyticus. The optimal hydrolysis conditions for pepsin were as follows: 35℃, pH 2.0, reaction time 2 hours,dosage of protease 3 000U/g, and solid to liquid ratio 1∶4. The molecular weight of the pepsin hydrolysate were mainly below 5000.

Abstract:The skin ulcer syndrome is a serious disease causing massive mortality and economic losses in cultured sea cucumber Apostichopus japonicus. Vibrio splendidus was identified as one of the most severely pathogeneses of this disease. In the present study, a DIG-labeled V. splendidus DNA probe based on the sequence of the 16S~ 23S rDNA intragenic spacers was synthesized and was used to establish in situ hybridization for detecting the bacterium in A. japonicus. V. splendidus-positive cells were observed in connective tissue, muscle tissue, epithelium of intestine and water-vacular tissues in artificial infected A. japonicus, while no cross-reaction was observed in tissues of healthy sea cucumber. The positive signals were clear in infected tissues, which could reveal the location and degree of the infection. Therefore, this established approach is useful to indicate the infection route and the pathogenesis of V. splendidus infection, which will provide basic data for disease control and animal health management.

Abstract:Effect of waterborne Cd2+ at different concentrations (0.005mg/L, 0.025mg/L, 0.05mg/L, and 0.1mg/L) on activities of glutathione S-transferase (GST), acid phosphatase(ACP) and alkaline phosphatase (AKP) in digestive glands and gills of Sinonovacula constricta were studied. It was found that the GST activity in the two tissues was stimulated by Cd2+during the exposure time in all treatments, however, those in higher-dose treatments (0.05 mg/L,0.1 mg/L) decreased with the prolonged exposure. The activation of ACP by Cd2+ in the two tissues began at the 6h time-point, and the activity increased with the increasing concentration of Cd2+.For ACP activity, the higher-dose group reached the peak value earlier than the lower-dose group, and was inhibited after 72h. Except 0.005mg/L dose-treatment in digestive glands, the AKP activities in the two tissues showed a“decrease-increase-decrease”trend during the 168h exposure time in the experiment, and those in higher-dose treatments were stimulated earlier than those in lower ones. AKP activity in each treatment decreased constantly after reaching the peak value respectively. The fluctuations in GST, ACP, and AKP activities in the experiment indicated that exposure to lower concentrations of Cd2+ could have affected the metabolism and detoxification system of the organism.

Abstract:Flow-through system for flatfish farming is transforming into industrialized Recirculation Aquaculture Systems in China,but development of the industry is greatly hampered by fish diseases. Currently, the main control methods against aquatic animal diseases include drug treatment, ecological prevention, and immunoprophylaxis. With the advantages of no pollution, no residue, and no drug tolerance, fishery vaccine possesses an overwhelming superiority, and its related research has attracted more and more attention. In this review, progresses and challenges on the study of fishery vaccine were summarized and analyzed to provide references for disease prevention and control in flatfish.