Abstract:Todarodes pacificus is one of important resources of the ocean economic Ommastrephidae in the world. In order to forecast the stock abundance of winter-spawning cohort, the catch per unit effort (CPUE) as abundance index from T. pacificus stock assessment report of Japan in 2013 is used to establish the forecasting model in this study. The correlation analysis between sea surface temperature (SST) in the spawning areas of 28°N-40°N and 125°E-140°E and CPUE from January to March during 2000-2010 was carried out respectively to select the significantly affecting factors in statistics. The multivariate linear model and BP neural network model forecasting abundance index of T. pacificus winter-spawning population were established and compared, and the actual CPUE in 2011 and 2012 was used for validation. The results showed that the spawning areas with high correlation coefficient between CPUE and SST in Jan. to Mar. are S1 (30.5° N, 136.5° E) and S2 (31.5° N, 136.5° E) in January, the correlation coefficient are 0.71 and 0.70 respectively; S3 (30.5° N, 137.5° E) and S4 (30.5° N, 135.5° E)in February, and the correlation coefficient are 0.87 and 0.84, respectively; S5 (37.5° N, 129.5° E) and S6 (37.5° N, 130.5° E) in March, and the correlation coefficient are 0.72 and 0.70, respectively. Total of five forecasting models including multivariate linear model and BP neural network model with different structure are established and compared. The BP 6-4-1 neural network model is the best, and the average prediction accuracy of the CPUE value during 2011-2012 attained 98%. This study suggests that the model can be used as the forecasting model of the stock abundance for T. pacificus winter-spawning cohort.

Abstract:Antarctic krill (Euphausia superba) is a key species in the Antarctic marine food web, which plays an important role in the southern ocean pelagic ecosystem. History of krill research has 90 years, the information of biomass and its distribution has been the focus of krill research, and the study methods have constantly been developed. From the early zooplankton dry weight method, then replaced by the conversion factors of production to biomass method (consumption of predators, primary production, larval abundance of krill), nets sample method, and now widely used acoustic method. This review analyses the advantages and disadvantages of each method, puts forward some suggestions for improvement of the current acoustic biomass assessment method from the five aspects of in-situ measurement of krill target strength model parameters, krill detection from the acoustic data, calculation of the krill nautical area scattering coefficients, correction of the krill fishery CPUE based on fishing vessel acoustic data, study on the krill swarm and fishery ground based on fishing vessel acoustic data which could provide a scientific basis for our country's Antarctic krill biological resources development and management.

Abstract:Aimed at analyzing how to build a fresh water recirculating ponds aquaculture system from energy quantization point of view, separated pond and sequencing pond were selected in Pond Ecological Engineering Research Center, Chinese Academy of Fishery Sciences (Shanghai, 30°57'1.89″N, 121°08'52.21″E), as well as a traditional pond (control pond). According to a whole-year data tested in 2016, energy flow characteristics of three kinds of fresh water recirculating ponds aquaculture system were discussed by applying software Ecopath with Ecosim 6.5. The results show that ecotrophic efficiency of fodder the highest in traditional pond (EE=0.77), separated pond (EE=0.75), sequencing pond (EE=0.99). Feed coefficient of traditional pond, separated pond, sequencing pond were 2.5, 2.8, 1.6, separately. These indicated that sequencing ponds which feeding amounts were distinguishing among different size specification were more advantageous to feed conversion. Ecotrophic efficiency of cladocerans, copepod, rotifer in traditional pond, separated pond, sequencing pond were 0.7/0.09/0.39, 0.8/0.02/0.12, 0.77/0.89/0.07, separately. This suggested that cladocerans could be used effectively by system. But different culturing modes can affect the ecotrophic efficiency of zooplankton. In addition, ecotrophic efficiency of rain group and bottom sediment group both less than 0.1, indicated that the energy from rain group and bottom sediment group could not be used effectively by system. Niche overlap analysis suggested that prey overlap index of separated pond were the highest and predator overlap index of sequencing pond were most highest than others. It means that the intensity of bait competition in seperated pond were the largest and sequencing pond had more pressure from the predator prey. Seperated pond could reducethe intensity of bait competition by strengthening regional water flow. Lindeman spineanalysis showed that the dominant energy flow ways of fresh water recirculating ponds aquaculture systemwere grazing food chain. System characteristic analysis suggested that the system maturity of separated pond and sequencing pond were superior to the traditional pond, means that it is possible to change the traditional single fragile pond ecological and improve system diversity by constructing compound aquaculture mode.

Abstract:The integrated agri-aquaculture system (IAAS) has become one of the main directions for the sustainable development of agriculture because of its good ecological environmental effect and the ability to produce enough green rice to meet the market demand for high quality food. It is important to understand the structural characteristics of soil bacterial community in this compound system for the improvement of planting and breeding and the realization of ecological regulation. In this study, Illumina high-throughput sequencing was used to compare the surface soil and rhizosphere soil bacterial community structure among rice-turtle co-culture (R-T) and rice monoculture (R-M), and provide the theoretical basis for the accumulation of data of rice-turtle co-culture ecology and the optimization of production technology for comprehensive cultivation of rice turtle co-culture. The results showed that Proteobacteria, Acidobacteria, Bacteroidetes, Nitrospirae and Chloroflexi were the main phyla in all paddy soil. Compared with R-M, the relative abundance of Chloroflexi, Nitrospirae and Acidobacteria increased and the relative abundance of Proteobacteria and Bacteroidetes was reduced in the surface soil of the R-T. In rhizosphere soil, compared with R-M, the relative abundance of Nitrospirae, Bacteroidetes and Proteobacter increased, and the relative abundance of Chloroflexi and Acidobacteria reduced in R-T treatments. The main genera were Acidobacteria bacterium_uncultured, Nitrosomonadaceae_uncultured, Nitrospiraceae_uncultured, Geobacter, Gemmatimonadaceae_uncultured and Xanthomonadales_norank. In the two models, the relative abundance of Nitrospiraceae_uncultured and Geobacter in rhizosphere soil was significantly different (P<0.05), and the relative abundance of Nitrosomonadaceae_uncultured, Nitrospiraceae_uncultured, Gemmatimonadaceae_uncultured and Acidobacteria bacterium_uncultured in the surface soils was significantly different (P<0.05). PCA and cluster analysis showed that R-T treatments exerted a significant effect on the bacterial community structure of surface soils, and also affected the rhizosphere soil bacterial community structure to a certain extent. Overall, this study provides microbial ecological evidences for the advantages of rice - turtle integrated system over rice monoculture.

Abstract:Four complete FZD cDNA sequences, designated fzd2, fzd3a, fzd4 and fzd10, were amplified by RT-PCR and RACE approaches from Pelteobagrus fulvidraco. The validated cDNAs encoding for fzd2, fzd3a, fzd4 and fzd10 were 2 176, 3 243, 2 509 and 3 021 bp in length, encoding peptides of 551, 695, 550 and 586 amino acid residues, respectively. The amino acid alignment and phylogenetic analysis revealed that Fzd sequences were relatively conserved among different vertebrates, and fzds of P. fulvidraco were more closely related to those of Ictalurus punctatus. All fzds mRNAs were expressed in all tested tissues (brain, spleen, kidney, gill, heart, muscle, mesenteric fat, liver and ovary), but at variable levels. On day 28, fzd3a mRNA levels increased with increasing waterborne Cu concentration, but mRNA expression showed no significant differences among the three groups. On day 56, fzd2 mRNA levels were the highest in 30 μg Cu/L group and showed no significant differences between other two groups, and mRNA levels of fzd3a, fzd4 and fzd10 showed no significant differences among three groups. The present study will be helpful to understanding the physiological functions of fzd genes.

Abstract:To explore the function of Dscam gene of Chinese shrimp Fenneropenaeus chinensis (FcDscam) during the immune priming response, we cloned the cDNA sequence using the rapid amplification of cDNA ends (RACE), and then analyzed the features of this gene based on bioinformatics software. The full length of FcDscam cDNA is 6624 bp, with a 5'-untranslated region (UTR) of 171 bp, a 3'-untranslated region (UTR) of 459 bp, and an opening reading frame (ORF) of 5 994 bp, and it encoded 1 996 amino acids. The protein encoded by FcDscam contains 1 signal peptide, 1 cytoplasmic tail, 1 transmembrane domain, 6 of fibronectin type Ⅲ (FNⅢ) and 10 of immunoglobulin(Ig). As shown by the homology search and neighbor-joining phylogenetic tree, FcDscam gene had the highest homology with that of Litopenaeus vannamei (92.4%). To induce the immune response, test animals were first fed with heat-inactivated WSSV bait for six days and infected again 12 days later. Samples were collected at 0, 6 and 12 d of the first-time infection and 12, 24, 48, 72 and 168 h of the second-time infection, respectively, for analysing the mRNA expression level of FcDscam by real-time PCR. On the 12th day of the first infection, its expression level in induced infection group began to increase, significantly different from those in the negative control group and the non-induced infection group. After 24 h of the second-time infection, its expression level in the infection group reached a maximum, significantly different from those of the negative control group and the non-induced infection group, and the expression level started to decline at the 48 h. Our research demonstrated the existence of the Dscam gene in F. chinensis, and its important role in the process of immune sensitization.

Abstract:A 56 d feeding experiment was conducted to investigate the effects of replacement of fish meal (FM) with wheat gluten meal (WGM) in diets on the growth, body composition, serum biochemical indexes and liver antioxidant ability of juvenile large yellow croaker, Larimichthys crocea[initial weight (10.49±0.03)g]. The basal diets were formulated by replacing 0% (FM), 25% (WGM25), 50% (WGM50), 75% (WGM75), 100% (WGM100) FM with WGM. The results showed that there were no significant differences in survival rate (SR), feed conversion ratio (FCR), hepatosomatic index (HSI), visceasomatic index (VSI) and condition factor (CF) among all diets; there were significant differences between the treatment and the control diets in the weight gain rate (WGR) and the specific growth rate (SGR). There were no significant differences in whole body crude protein, crude lipid, water and ash content. There were no significant differences in muscle crude protein, crude lipid and water content, but in muscle ash content, there were significant differences between WGM50, WGM75 diets and FM, WGM25, WGM100 diets. There were no significant differences in serum alanine aminotransferase (ALT) and aspartate amino-transferase (AST) content. For liver superoxide dismutase (SOD) activity, it was significantly lower in WGM25, WGM100 diets than FM, WGM50 and WGM75 diets; for liver malondialdehyde (MDA) activity, it was significantly lower in WGM50 diet than FM, WGM25 and WGM100 diets; for liver catalase (CAT) activity, there were no significant differences; for liver glutathione peroxidase (GPx) activity, it was significantly higher in WGM100 diet than the other diets. From what have been discussed above, we can conclude that replacing 100% FM with WGM is suitable for juvenile large yellow croaker, and would not affect the growth performance.

Abstract:This experiment was conducted to study the effect of replacement of fish meal by compound protein (fermented rapeseed meal+cotton meal+silkworm pupae+mulberry leaves) on the growth, body composition, antioxidant ability and biochemical indices of hybrid snakehead[with the initial weight (22 g)]. Five isonitrogenous and isolipid diets (CP 42%, EE 8.5%) were formulated to contain different levels of compound proteins based upon the basal diet to replace fish meal 0%, 12%, 24%, 36% and 48%. After 8 weeks, the results showed as follows:when the replacement ratio of fish meal by compound protein is more than 12%, the final body weight (FBW) and the specific growth rate (SGR) were significantly decreased, and reached a minimum at 48% substitution level. A lower protein efficiency ratio (PER) and higher feed conversion ratio (FCR) were observed at the 36% and 48% substitution levels. There is no significant difference in feeding rate (FR) for each test group. The replacement level of compound proteins decreased significantly body crude lipid, viscera somatic index (VSI) and intraperitoneal fat ratio (IPF), and increased significantly whole body moisture. With the compound protein level increasing, the activity of trypsin decreased significantly, whlie the activity of intestinal lipase increased significantly. When the compound protein level is higher than 24%, the activities of glutamyl pyruvic transaminase (GPT), superoxide thandismutase (SOD) and the catalyse (CAT) activities significantly increased. Serum CHO was decreased observably as compound protein ratio is more than 12%, but blood glucose content was decreased observably as compound protein ratio is more than 36%.There were no significant difference in total cholesterol (TC), total protein (TP) and albumin (ALB) for each test group. Results of above show that a suitable percentage (12%) of compound protein replacement of fish meal does not affect the growth of hybrid snakehead. And high replacement level would inhibit the growth of hybrid snakehead, but it can improve the glucolipid metabolism and antioxidant capacity of hybrid snakehead.

Abstract:In order to further explore the molecular mechanism that KK-42 shortens the molt cycle of the juvenile prawn Macrobrachium nipponense, the full-length cDNA sequence of NAGase, the rate-limiting enzyme in chitin catabolism, was cloned from carapace by RACE technique. The relative expression of NAGase mRNA and its activity in cuticular tissue were determined before and after KK-42 treatment. Sequence analysis showed that the full length NAGase cDNA was 2 536 bp, encoding 617 amino acids. Homology analysis indicated that NAGase was less conserved and had the highest similarity of 68% to that from Litopenaeus vannamei. Phylogenetic analysis showed that the amino acid sequence of NAGase from M. nipponense was clustered into one major group with that from Portunus trituberculatus, L. vannamei, and Fenneropenaeus chinensis. The NAGase sequence from L. vannamei and F. chinensis shared more similarities with each other, M. nipponense belonged to a separate branch. The mRNA concentration of cuticular NAGase in control group peaked at premolt D₀ stage. Once treated by KK-42, the mRNA content increased significantly, with a 253% rise in D₄ phase at 3 h, as well as a 226% or 187% rise in C or D₀ phase at 6 h. The activity of NAGase rose gradually from C to D₄. KK-42 treatment could cause significant increase of NAGase activity in C and D₀ stages, especially in C stage, during which the activity increased by 11.26, 5.99 and 7.15 folds, respectively, at 3, 6 and 12 h. The results above suggest that the induction effect of KK-42 on the cuticular NAGase of M. nipponense may be one of the molecular mechanisms to shorten the molt cycle.

Abstract:Estrogen plays an important role during the regulation of ovarian development in crustaceans, and tamoxifen (TAM) is a commonly used estrogen antagonist for the studying of molecular mechanism between estrogen and ovarian development of crustacean. This study was designed to investigate the effect of estrogen antagonist on survival rate, gonadosomatic index (GSI), hepatosomatic index (HSI), and expressions of the related genes to ovarian development of female Portunus trituberculatus by in vivo experiment, culture experiment and quantitative PCR (qPCR). The results showed that different concentrations of TAM had no significant effects on the survival rate and HSI among all treatments, but could suppress GSI. The results of qPCR showed that TAM had significant effects on the expression levels of Vg (vitellogenin), ERR (estrogen related receptor), RXR (retinoid X receptor) and EcR (ecdysone receptor) genes in different tissues of P. trituberculatus. The expression levels of Vg gene in ovary and hepatopancreas were obviously inhibited by TAM. For ERR gene, low concentration of TAM (6.7 and 13.4 μg/g) could promote the ERR transcription in the ovary and thoracic ganglion, while different from the results of low concentration, the significant decrease was found on the ERR mRNA levels in the most examined tissues from the high concentration of TAM treatment (20 μg/g) compared to the control treatment. The expression profiles of EcR affected by TAM were similar to ERR in ovary and hepatopancreas. In addition, the low concentration of TAM could promote the expression of RXR gene in ovary, but no significant differences were found on RXR expression levels in the hepatopancreas. In conclusion, these results suggested that TAM could inhibit the Vg expression levels, possibly resulting in the low GSI of female P. trituberculatus, and ERR and EcR might be involved in regulatory processes of estrogen or exogenous estrogen antagonist on ovarian development.

Abstract:An 8-week feeding trial was conducted in a recirculated system to study the effect of dietary n-3/n-6 HUFA (D1:29.54, D2:23.04, D3:18.97, D4:9.06, D5:6.86, D6:3.87) on growth performance, the fatty acid composition of whole body and serum biochemical indices in turbot (Scophthalmus maximus). Six diets were formulated to feed six groups of juvenile turbot[mean initial weight (12.18±0.01) g], respectively. Each diet was randomly fed to triplicate groups of 35 fish per tank. Results showed that dietary n-3/n-6 HUFA had no significant effect on the survival rate(SR) of turbot. With the decreasing of the dietary n-3/n-6 fatty acid ratios, the weight gain rate (WGR), protein efficiency ratio (PER) and specific growth rate (SGR) increased first, then decreased. And WGR, PER and SGR of D6 group was significantly lower than other groups. PER of D2 group was significantly higher than other groups. Crude protein and ash of whole body increased at the beginning and then decreased. Crude protein and ash of muscle of D6 group was remarkably lower than the others. The fatty acid composition analysis showed that the concentration of ARA increased with decreasing of dietary n-3/n-6 HUFA, while EPA, DHA, n-3/n-6 PUFA and n-3/n-6 HUFA content followed the opposite pattern. Acid phosphatase (ACP) and superoxide dismutase (SOD) were increased among dietary treatments. Serum lysozyme (LZM) activity increased with reducing dietary n-3/n-6 HUFA from 29.54 to 23.04, and decreased with further decrease of n-3/n-6 HUFA from 23.04 to 3.87. Total antioxidant capacity (T-AOC) showed a similar trend with serum lysozyme activity with the highest value in the ratio of 18.97, significantly higher than that in the control and ratio of 3.87 groups. These results suggested that dietary n-3/n-6 HUFA, especially moderate n-3/n-6 HUFA (18.97~23.04), enhanced growth and immune response and modified the chemical composition of whole body and muscle of juvenile turbot.

Abstract:To select the reference genes applicable for 17 development stages and 7 tissues of Ruditapes philippinarum, expression stabilities of elongation factor 1 alpha gene (EF1A), TATA-box binding protein gene (TBP), histone gene (HIS), cytochrome b5 gene (CYTB5), ubiquitin-conjugating enzyme gene (UCE), ribosomal protein L8 gene (RPL8), ribosomal protein S23 gene (RPS23), ribosomal protein L2 gene (RPL2), cytochrome C gene (CYTC), growth factor receptor-bound protein 2 gene (GFRP2), β-actin gene (ACT) and tubulin gene (TUB) were then evaluated with three algorithms-geNorm, NormFinder and ΔCt methods, respectively. The results suggest that CYTC, CYTB5 and RPS23 were the optimal reference gene combination for different development stages; CYTB5 and GFRP2 were recommended for qRT-PCR normalization of different tissues. The ACT was proved to be the most unstable in different development stages and different tissues of R. philippinarum.

Abstract:This experiment was aimed to study the effect of different carbohydrates and different carbohydrate levels on mRNA expression of glycolytic enzyme (glucose kinase, GK; hexokinase, HK), gluconeogenesis enzyme (Glucose -6- phosphatase, G6Pase; phosphoenolpyruvate carboxykinase, PEPCK), glucose metabolism related genes (Insulin-like Growth Factor-Ⅰ, IGF-Ⅰ; Growth Hormone Receptor, GHR) in different feeding stages of Songpu mirror carp (Cyprinus carpio). Four experimental diets were formulated to contain two carbohydrates (starch and glucose) diets with two levels (250 g/kg and 500 g/kg) (Low level starch group:LS; High level starch group:HS; Low level glucose group:LG; High level glucose group:HG) two carbohydrates (glucose and starch) and two carbohydrate levels (25% and 50%) (LS/HS/LG/HG) using 2×2 double factor experimental design, 420 Songpu mirror carp (mean weight=[8.30±0.15] g) were randomly divided into 4 dietary treatments with 3 triplicates and 35 fish per triplicate and were reared for 7 weeks. The results showed that in different feeding stages, the mRNA expression levels of HK gene and IGF-Ⅰ gene in different experimental groups were basically in the same trend. The mRNA expression levels of HK gene at feeding 1W was significantly increased and then decreased. The mRNA expression level of IGF-Ⅰ gene was significantly increased at feeding 3W. IGF-Ⅰ gene expression increased significantly at feeding 3W. In different feeding stages, the mRNA expression levels of GK, PEPCK, G6Pase and GHR genes were affected by carbohydrate levels and carbohydrate types. At low carbohydrate level (LS group and LG group), the mRNA expression levels of these genes showed the same trend. The mRNA expression levels of GK and GHR genes were significantly higher at feeding 1W and then began to decline. The mRNA expression level of PEPCK gene was the highest at feeding 3W. The mRNA expression level of G6Pase genes were significantly higher at feeding 1W, then began to decline and showed a rising trend at feeding 7W. At high carbohydrate levels, the mRNA expression level of GK gene in HS group was not significantly different at different feeding stages. But the mRNA expression level of GK gene in HG group was increased significantly at feeding 1W. The mRNA expression level of PEPCK gene in HS group and HG group had no significant difference at different feeding stages. The mRNA expression level of G6Pase gene in HS group had no significant difference at different feeding stages. But the mRNA expression level of G6Pase gene in HG group was increased significantly at feeding 3W. The mRNA expression level of GHR gene in HG group had no significant difference at different feeding stages, while the mRNA expression level of GHR gene in HS group was increased significantly at feeding 3W.In the early feeding stage (1W), the mRNA expression level of HK gene was significantly promoted by high carbohydrate diet. While, the mRNA expression levels of PEPCK, G6Pase and GHR genes were suppressed by high carbohydrate diet. In conclusion, this study investigated the effects of different carbohydrates and carbohydrate levels on the expression trend of enzymes and genes involved in glucose metabolism at different feeding stages. It provides a theoretical basis for the application of carbohydrate in feed.

Abstract:There were more than thirty countries and regions which placed artificial reefs in coastal areas. However, more than fifty percent of these Artificial Reefs failed due to improper site selection, lack of supervision and planning. Placing the Artificial Reefs consumes large amount of time and finances which means that it's impossible to change Artificial Reefs location. Therefore, the success of Artificial Reefs depends on the site selection. Most studies of Artificial Reefs focused on their ecological effects, and these results could be used for evaluating the effectiveness, but they did not provide necessary references for Artificial Reefs site selection. For assessing the site selection suitability of Artificial Reefs, our study took island area protective Artificial Reefs site selection as the theme and the Multi-Criteria Decision Method was used in this study. Expert system, Analytic Hierarchy Process (AHP), GIS spatial analysis and raster calculation were also combined. The effective main criteria (physical, biological and management) and sub-criteria (bottom slope, substrate, current, depth, catch, density, larval dispersal, existing larvae, distance to pollution source, distance to channel, distance to coastline) for protective Artificial Reefs were identified by paper reviewing and expert knowledge. Using the pair-wise comparison and AHP, the weight of main criteria and sub-criteria were ranked, and the results showed the weight of physical, biological and management were 0.481, 0.405, 0.114 respectively. The weight of sub-criteria were corresponding 0.101, 0.186, 0.097, 0.098, 0.095, 0.184, 0.048, 0.079, 0.068, 0.030, 0.016. The site selection suitability in Ma'an Archipelago showed spatial heterogeneity after calculating overlapped criteria map. The corresponding analysis of depth, substrate type, resource density distribution and suitability distribution showed that the model results were consistent with the suitability criteria. And the high suitability areas where Artificial Reefs have been placedalso showed effectiveness. Therefore, the assessment model of this study could be used for assessing the site selection suitability of protective artificial reefs in similar island areas.

Abstract:A 16-week feeding experiment was conducted to study the effects of different dietary carbohydrate and protein levels on growth, body composition, intestinal digestive enzyme activity and serum indexes of large-size grass carp (Ctenopharyngodon idella)[initial body weight (398.6±5.9 g)]. Seven extruded diets with different levels of carbohydrate (C) and protein (P) (C31P30, C34P28, C37P26, C40P24, C43P22, C46P20, C49P18) were made. Experimental results showed that with protein levels decreasing and carbohydrate levels increasing, weight gain rate decreased significantly, protein efficiency significantly increased, hepatosmatic index, viscera index, intestinosomatic index and the fat content of muscle and liver increased significantly. However, the protein content in muscle had no significant difference among dietary treatments. The carbohydrate levels affected significantly the glycogen content in liver and muscle. The glycogen content in liver and muscle increased significantly when the carbohydrate levels were equal to or over 46% and 40%, respectively. The activities of intestinal trypsin and amylase decreased firstly, and then showed a tendency of increase, and lipase activity significantly increased. The content of serum total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL), and glutamic-oxalacetic transaminase (GOT)/glutamic-pyruvic transaminase (GPT)values had a rising trend with dietary carbohydrate levels increasing and protein level decreasing. These results indicated that lower protein (protein levels below 26%) and higher carbohydrate (carbohydrate level above 37%) imposed a negative effect on growth performance, and the hepatosmatic index, viscera index, intestinosomatic index and the fat content of muscle and liver were significantly increased at high level of dietary carbohydrate.

Abstract:The community structure of Cephalopods and its relationship with environmental factors were analyzed based on the bottom trawl data of nine months from May 2011 to April 2012, in order to reveal the resource status of Cephalopods in Laizhou Bay. A total of 6 species belonging to 3 orders, 3 families, 4 genera, were collected by 148 hauls. Both the biomass density and the individual density were highest in October 2011 and lowest in March 2012. The annual average of biomass density and individual density were 3 111.39 g/h and 723.54 ind/h, respectively. Loligo sp. was the dominant species, with the annual index of relative importance (IRI) reaching up to 13097. The spatial distribution of individual density of Cephalopods changed with different month in Laizhou Bay. The individual density of Cephalopods was the highest in the central and southern Laizhou bay from June to July, and the highest in the central and northern Laizhou bay from August to November 2011. The individual density of Cephalopods were very low from March to May. CLUSTER and MDS analysis indicated that 9 months were divided into 4 groups at 85% similarity level. ANOSIM analysis indicated that the community structure of Cephalopods of random two groups were significantly different. SIMPER analysis indicated that Loligo sp. contributed the most to the group distinguishing. Pearson correlation analysis indicated that the density of zooplankton matched the density of Cephalopods best. Reproductive migration and wintering migration were the principal influence factors on the variation of spatial distribution of Cephalopods in Laizhou Bay. The present results would be helpful to better utilizing and protecting the Cephalopods resources in Laizhou Bay.

Abstract:The present study was conducted to investigate the effects of dietary Eucommia ulmoides (EU) on growth performance, flesh quality, collagen genes COL1A1 and COL1A2 expression of grass carp (Ctenopharyngodon idella). A total of 120 grass carp with an initial body weight of (215.0±0.4) g were randomly allocated into 2 groups with 3 replicates per group and 20 fish per replicate. The fish were fed formula diet without (control) or with the supplementation of 2% Eucommia ulmoides (EU) for 8 weeks. The supplementation of 2% EU did not significantly affect the growth performance of grass carp when compared with the control (P>0.05), but increased the collagen content in muscle, skin and liver (P<0.05). Total essential amino acids (TEAA), total non-essential amino acids (TNEAA) and total amino acids (TAA) in muscle of grass carp fed EU diet were significantly higher than those of control group. Fish fed EU showed significantly lower flesh thawing loss and centrifugal loss (higher water holding capacity) (P<0.05), but muscle fiber density and muscle fiber diameter showed no difference between the two groups (P>0.05). Moreover, dietary EU significantly promoted the relative expression level of COL1A1 and COL1A2 mRNA in muscle, skin at the 4^th week, the 8^th week, and the expression in liver at the 8^th week (P<0.05). In conclusion, dietary EU could improve the flesh quality of large-size grass carp.

Abstract:The fish community structure and its relationships with the environmental factors in the Nature Reserve of Trichiurus japonicus were studied based on the data collected from bottom trawl surveys in spring and autumn 2014 by using non-metric multi-dimensional scaling (NMDS), canonical correspondence analysis (CCA) and classification and regression tree (CART). In spring, a total of 75 fish species were sampled in the survey, belonging to 63 genera, 49 families, and 14 orders. In autumn, a total of 78 fish species were captured, belonging to 64 genera, 50 families, and 15 orders. Spatial structure of fish assemblage in spring and autumn could be classified into two groups. ANOSIM (analysis of similarity) indicated that the fish species composition varied significantly between two groups in two seasons. The canonical correspondence analysis (CCA) suggested that the main environmental factors affecting the spatial distribution of fish assemblage in spring and autumn were water temperature, salinity, depth and zooplankton. The average values of diversity index and richness index were 1.65±0.60 and 2.46±0.90 separately in spring, while the average values of diversity index and richness index were 1.42±0.53 and 1.89±0.60 separately in autumn. The classification and regression tree (CART) indicated that the diversity and richness index in spring and autumn were mainly affected by Chl.a, DO, depth, pH and zooplankton (euphausiid and planktonic larvae). The main factors affecting the diversity index were water temperature, depth and salinity in autumn, while the main factors affecting the richness index were water temperature and depth.

Abstract:With the widespread use of antibiotics in aquaculture, the bacterial antibiotic resistance has become a main problem in environment and food safety. This paper aims to analyze the statistical information of shrimp intestine bacterial drug resistance in Tianjin area, and to provide theoretical guidance for the shrimp disease control and improving the safety of aquatic products. Shrimp intestine organisms were isolated and cultured, then the bacterial antibiotic resistance and the antibiotic resistance genes (ARGs) of cultured Litopenaeus vannamei were determined in the breeding base of Jinnan, Hangu and Xiqing districts of Tianjin city. Among the total isolated 1 219 strains, 215 strains were identified, and were classified into 56 different species, mainly Bacillus, Vibrio parahaemolyticus, Staphylococcus, Klebsiella pneumoniae, V. Xiluo, V. alginolyticus, Shewanella sp., Enterobacter hormaechei, Kurthia sp., Pseudomonas stutzeri, Rhodobacter capsulatus, Serratia liquefaciens, Acinetobacter sp., Pseudomonas, Pseudoalteromonas whanghaensis, V. cholerae. 215 strains were selected to analyze the antibiotics sensitivity. The experiment results showed that the antibiotic resistance of the intestinal bacterias was universal, especially to the beta lactam ampicillin, bacitracin glycopeptide, quinolones of lomefloxaxin and sulfonamides resistance. Therefore, four main kinds of antibiotic resistance gene (streptomycin: strA-strB, sulfonamides SulI, SulⅡ, SulⅢ, tetracyclines:TetA, TetC, TetG, penicillin: blaoXA-1, blaPSE-1, blaTEM) and integron (inT1 and inT2) of 82 strains with crossed antibiotic resistance were further determined. The results showed that all of the drug-resistant strains were detected with antibiotic resistance genes positive. The positive rate of resistance genes of sulfonamides, penicillin and tetracycline was 63%, 61.4% and 35.4%, respectively. And only tetA was detected in tetracycline resistance genes. The positive rate of integron gene was 42.1%. Among them, 67.1% of the strains had multiple resistance genes.