Abstract:B-H model, a single-species management model, is not suitable for multi-species coexistence situation due to several limitations. In this paper, a multi-species management approach is created based on B-H model by replacing "catchable age" and "fishing mortality" of single species management model with "catchable mesh size" and "fishing effort" of multi-species management model to achieve multi-species management objective. The multi-species management approach was used to test with the two typical species of the East China Sea, hairtail and small yellow croaker based on literatures. The big differences in body shape and body size between hairtail and small yellow croaker and the small optimum yield overlapping area demonstrated that these two species are not suitable for the integrated management, which should be managed separately by different fishing areas or different fishing vessels. This model has merits like intuitive, easy-judging and timely but with limitations of short-term effectiveness and similar shape requirements. To promote the application of this multi-species management approach, it needs to further accumulate various basic data for the relevant elementary parameters, standardize fishing efforts and explore ways to improve the model accuracy.

Abstract:In this study we analyzed the spatial distribution and the diversity of the fishery species in the Yangtze River estuary and its adjacent waters, and explored how they are affected by the environmental factors, based on the bottom trawl survey data collected from August 2012 to May 2013. A total of 114 fishery species (17 orders, 66 families and 90 Genera) were collected, including 58 fish species (12 orders, 36 families and 50 Genera), the richest species was found in Perciformes (26 species), 49 crustacean species (2 orders, 25 families and 33 Genera) and 7 cephalopod species (3 orders, 5 families and 6 Genera). The dominant species were season-dependent, whereas Harpodon nehereus was the only all-year-round dominant species. The average catch per haul was highest in autumn (29.20 kg/h·net), followed by that in spring (17.95 kg/h·net), summer (14.60 kg/h·net), and the least in winter (10.15 kg/h·net). Generally the demersal fish and crustaceans constituted the majority in the catch in all seasons, and the percentage of the pelagic fish was only slightly higher in spring (20.1%). The diversity indices of fishery species in spring and summer were higher than those in autumn and winter. The migration index and alternate index of fishery species were higher in spring (163) and summer (176), which meant the higher stability in fisheries community in the Yangtze River estuary. The migration index was close to 0 in summer (6) and winter (–5), suggesting that the immigration and emigration of the fishery species were in a state of balance. The number of fishery species and total catches were significantly positively correlated with the catches of the demersal fish and the crustaceans respectively in all seasons (P<0.01). The number of fishery species in autumn was positively correlated with both the sea surface temperature (P<0.05) and the water depth (P<0.01). These results showed a trend of increase in the low-valued species in the Yangtze River estuary and the adjacent waters. Our study suggested that there were significant seasonal variations in the structure of the fishery resource, and that the number of fishery species, the total catches and the diversity indices were highly related to the sea surface temperature and water depth.

Abstract:Nutrient components of brittle stars Ophiopholis mirabilis, Stegophiura sladeni and Ophiura sarsii vadicola collected in the North Yellow Sea of China were studied. Alive samples were frozen at −70℃, and then dried in a lyophilizer. The results showed that the moisture content of the brittle stars was less than 50%, and it was 41.61% in S. sladeni that was significantly lower than those in the others (P<0.05). The ash content in S. sladeni was 80.70%, which was higher than those of the others (P<0.05). The total amino acid content in the brittle stars was low, and the highest one was in O. mirabilis with 14.90% (P<0.05). The percentage of essential amino acids to the total amino acids (EAA/TAA) of O. mirabilis, S. sladeni and O. sarsii vadicola was 35.37%, 29.58% and 34.97%, respectively. The essential amino acids and flavour amino acids in O. mirabilis were significantly higher than those in the others (P<0.05). Furthermore, the highest amino acids score, chemical score and essential amino acids index were in O. mirabilis. The unsaturated fatty acids in O. mirabilis, S. sladeni and O. sarsii vadicola were 52.91%, 50.03% and 64.31%, respectively, and the highest one was in O. sarsii vadicola (P<0.05). However, the lowest saturated fatty acid was in O. sarsii vadicola with 13.32% (P<0.05). All species were rich in mineral element. The Ca and Mg contents in O. sarsii vadicola were significantly higher than those in the others (P<0.05), which were 348000 mg/kg and 28500 mg/kg, respectively. The results suggested that these three species are not good protein sources but suitable for developing function food for Ca supplement. The high carbonate content in brittle stars showed that brittle stars are probably important to the ocean carbon sink.

Abstract:In this study Nibea albiflora juveniles with the average weight of (5.0±1.4) g and the average length of (8.3±0.8) cm were divided into 3 salinity groups including salinity 23 as the control group and salinity 9 and 16 as the stress groups. Fish samples were collected on the 0, 1st, 3rd and 7th day. To evaluate the effects of low salinity on the ion regulation and respiratory metabolism of N. albiflora, we tested the changes in activities of Na+/K+-ATPase (NKA), Ca2+-ATPase, H+-ATPase, lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) in gills, and the level of cortisol in the serum. In response to the low-salinity stress, the NKA activity increased significantly (P<0.05), and the Ca2+-ATPase activity decreased after a slight increase in the beginning, and the H+-ATPase activity first increased and then recovered to the initial level. The enhanced activities of NKA, Ca2+-ATPase and H+-ATPase could provide more energy for the ion transport to maintain the dynamic balance of the osmotic pressure. The cortisol level in the serum fluctuated significantly (P<0.05) during the low-salinity stress, and the cortisol levels of salinity 9 or 16 group increased alternately. The LDH activity in the gill increased significantly (P<0.05), and the activity of the salinity 9 group was higher than that of the salinity 16 group. The SDH activity in the gill frist increased and then decreased, and the activity of the salinity 9 group increased significantly on the 7th day (P<0.05). Environmental stress would affect the normal aerobic respiration of N. albiflora. Along with the osmotic adjustment, the need of oxygen increased, which may significantly enhance the SDH activity. Noticeably, two experimental fishes died in the salinity 9 group during experiment. The feeding and activity of N. albiflora juveniles in the salinity 16 and 23 groups were normal，whereas they were impaired in the salinity 9 group. Our results suggested that low salinity could have significant effects on the ion regulation and respiratory metabolism of N. albiflora. Excessively low salinity may overwhelm the adaption ability of N. albiflora and cause harm to the health of the fish.

Abstract:Here we conducted a 2×3 two-factorial experiment to evaluate the effects of Chitosan oligosaccharide(COS) and Xylo-oligosaccharide(XOS) on the growth, body composition and serum biochemistry of juvenile turbots (Scophthalmus maximus) with initial body weight of (15.46±0.06) g. The feeding trial lasted 8 weeks. Totally 9 diets were formulated to provide graded levels of COS (0, 0.5%, and 1.0%) and XOS (0, 0.5%, and 1.0%). The results showed that the levels of COS and XOS significantly affected the weight gain, specific growth rate, feed conversion, protein efficiency rate, muscle moisture and crude lipid of juvenile turbots (P<0.05). The addition of COS and XOS at different levels did not generate significant differences in the body composition and the muscle ash content (P>0.05). There were significant interactions between XOS and COS in the growth rate, weight gain, whole fish fat and ash, muscle fat and protein, serum triglycerides, high-density lipoprotein cholesterol, lysozyme and alkaline phosphatase (P<0.05). The results above implied that the combination of XOS and COS could significantly improve the growth of juvenile turbots, moderately enhance the non-specific immunity, and facilitate the regulation of the level of the serum lipid. According to our experimental data we recommend that 0.5% COS and 1.0% XOS should be the optimal combination in the diet.

Abstract:Newly hatched larvae do not have feeding activities. Instead, they obtain nutrients from the oil globule and yolk sac during the endogenous period. The oil globule and yolk sac are gradually consumed and absorbed with the development of the larvae. Then the larvae start to feed on a combination of baits, the oil globule and yolk sac for energy, and their development progress into the mixed vegetative period. As the oil globule and yolk sac are fully consumed, the larvae develop into the exogenous vegetative stage when they acquire the nutrients solely from the external environment. Here we investigated the growth, feeding and survival of the Epinephelus moara. The larvae were divided into a fasting group and a control group. In the fasting group the larvae were deprived of feed, and in the control group they were fed on the 3rd day after hatching. The feeding was conducted at temperature (23±0.5)℃ and salinity 29-30. We found that the body length of the larvae grouper grew negatively, and that they started feeding on the 3rd days after hatching. The yolk sac and oil globules were exhausted on the 4.5 day after hatching. We also found the initial feeding rate of the larvae changed over the days after hatching, first increased followed by a continuous decrease till 0 eventually. The maximum initial feeding rate (66.67%) appeared on the 5.5 day after hatching when the yolk sac and oil globules were completely exhausted. The initial feeding rate reduced to half of the peak value on the 6th day after hatching when the larvae reached PNR (point-of -no-return). Therefore the nutrition-mixture stage of the larvae lasted for 2.5 days, and 3-6 days after hatching should be the crucial feeding period of the larvae

Abstract:In this study we investigated the expression patterns of lipoprotein lipase and hepatic lipase genes, as well as the effects of the glucose solution and the vitamin C solution on its regulation during the development of the yolk-sac larva of Carassius auratus gibelio. In the preliminary experiments, the membrane break time and hatching rates were recorded to determine the optimal concentrations of glucose and vitamin C. Solutions without (control group) and with glucose (optimal concentration 15 g/L glucose group) or vitamin C (optimal concentration 30 mg/L vitamin C group) were used for hatching, and the gene expression patterns of lipoprotein lipase and hepatic lipase were analyzed. Real-time PCR was applied to measure the mRNA level of lipoprotein lipase and hepatic lipase, and to test how glucose and vitamin C regulated the expression of two genes during the development of the yolk-sac larva. We found that genes of lipoprotein lipase and hepatic lipase were expressed at the endogenous nutrition stage, the mixed nutrition stage and the exogenous nutrition stage, and that the expression was increased over time. The mRNA levels of both lipoprotein lipase and hepatic lipase were up-regulated from the endogenous nutrition stage to the exogenous nutrition stage in the group treated with 15 g/L glucose (P<0.05). Similarly they were also re-regulated from the endogenous nutrition stage to the exogenous nutrition stage in the group treated with 30 mg/L vitamin C, which caused a significant increase in the expression of lipoprotein lipase mRNA during the yolk-sac larva developmental stage. Vitamin C increased the expression of hepatic lipase mRNA during the mixed nutrition stage and the exogenous nutrition stage (P<0.05). Our study suggested that the lipid catabolism of C. auratus gibelio increased during the mixed nutrition stage, and that appropriate concentrations of glucose (15 g/L) and vitamin C (30 mg/L) could induce the mRNA expression of lipoprotein lipase and hepatic lipase.

Abstract:Vibrio anguillarum widely exists in aquatic environments and has been recognized as one of the prominent waterborne pathogens that undermine the aquaculture industry worldwide. In this study, we investigated the prevalent distribution of eight virulence-associated genes in the V. anguillarum strains isolated from Scophthalmus maximus, Cynoglossus semilaevis and Cyprinus carpio, and improved the detection of V. anguillarum by using duplex PCR and LAMP assays. Six genes (empA, vah1, vah4, flaA, rtxA, and tonB) were detected in all 22 pathogenic strains of V. anguillarum, but virA and angM were not detected. The duplex PCR assay was established with vah4 and rtxA genes as molecular markers. Two gene fragments from the chromosomal DNA of V. anguillarum were detected in one PCR reaction with the detection limit of 2.4×103 CFU/ml. The assay in 6 other control strains generated negative results. The LAMP assay was established with vah4 as the molecular marker. The positive reaction was shown as stair-step amplified bands and the detection limit was 2.4×101 CFU/ml. The assay produced negative reactions in 6 types of control pathogenic bacteria (no amplified bands). The LAMP method was 100 times more sensitive than the PCR method. Therefore we concluded that the LAMP assay could be a sensitive, rapid and simple tool for the detection of V. anguillarum, and recommend to employ this method in the early diagnosis of V. anguillarum infection in aquatic animals.

Abstract:White spot syndrome virus (WSSV) is a widespread and disastrous viral pathogen of cultured shrimp that infects many different species of crustaceans. Tetraspanin-3 protein belongs to the tetraspanin superfamily, which plays an important role in signal transduction and immune process. Increasing evidence has shown that tetraspanins play important roles in virus invasion, penetration and fusion events. Antibody to the large extracellular loop (LEL) of Tetraspanin-3 of Fenneropenaeus chinensis can block the WSSV infection. However, whether the F. chinensis Tetraspanin-3 is involved directly with WSSV remained largely unknown. In this research, we cloned the LEL fragment of Tetraspanin-3 from shrimp F. chinensis (FcT3L) and ligated it with prokaryotic expression vector pBAD/gⅢA to get recombinant expression vector pBAD/gⅢA-FcT3L. After transformed into E. coli (TOP 10) and induced using the L-arabinose, we successfully obtained the pure recombinant protein using Co2+ affinity chromatography purification. Mass spectrometry analysis showed the correctness of the recombinant protein. Moreover, FcT3L was labeled with DIG and incubated with WSSV and the results showed that FcT3L can interact with VP26. Furthermore, recombinant VP26, VP28N, VP28C and VP37 were separated by SDS-PAGE and transferred to PVDF membranes. After incubating with DIG-labeled FcT3L, a positive band was shown with VP26. To confirm the interaction of FcT3L with VP26, FcT3L was coated with 96-well plates and different amount of VP26 was added. ELISA assay showed that the interaction between FcT3L and VP26 grew stronger with the increasing concentration of FcT3L. Results suggested that VP26 might bind to the Tetraspanin-3 and act to help the WSSV diffuse and penetrate into the cytoplasm. The detailed mechanism needs further investigation.

Abstract:The objective of this study on Pacific white shrimp (Litopenaeus vannamei) was to evaluate the fillet yield performance of different families in the conservation population. A multivariate linear regression equation of fillet yield was established to find alternative indirect traits of fillet yield. A total of 2094 shrimps from 42 full-sib families were randomly sampled for measuring phenotypic traits and fillet yield in the conservation population after rearing 350 days. These traits were measured for each shrimp: fillet weight(FW), body weight(BW), carapace length(CL), segment length(SL), the length from the base of eye stalk to the 6th segment(ESL), body length(BL), total length(TL) and condition factor(CF). Fillet yield was obtained after anatomizing the shrimp and taking the meat. Differences of fillet yield between different families were analyzed using the ANOVA method. The component of variance and heritability of fillet yield trait were estimated using REML method and an individual animal model. Correlation coefficients between the phenotypic traits and fillet yield were calculated, and the prediction equations for fillet yield were established using step-wise regression analysis method. The results showed that the average fillet yield was 53.59% in L. vannamei. The mean of fillet yield between families ranged from 50.25% to 59.51%. The variation coefficient of fillet yield was 6.08% and there were significant differences between families (P<0.01). Three traits having strong correlation with fillet yield were FW (r=0.478), ESL (r=0.376) and SL(r=0.370). The multivariate linear regression equation for fillet yield was composed of ESL, BW and ESL/TL, and the coefficient of determination of the equation was 0.172. This study first implied that difference between families for fillet yield was significant. Although genetic variation for fillet yield was poor at the family level in the conservation population of L. vannamei, improved strains or populations will be introduced to increase genetic gain of fillet yield, and desirable genetic gain will be obtained using inter-family and within-family selections. Indirect selection traits with moderate correlation with fillet yield were found because correlation coefficient between phenotypic traits and fillet yield varied from low to moderate. In this study, the prediction accuracy of the constructed multiple linear regression equation for predicting fillet yield was low. Therefore, new technologies including ultrasound, magnetic resonance imaging should be developed, and new traits including cross-sectional area of muscle, circumference of segment should be measured in the future study.

Abstract:Poly-β-hydroxybutyrate (PHB) is a polymer of the short-chain fatty acid β-hydroxybutyrate. β-hydroxybutyric acid facilitates food digestion, absorption, and the protein and mineral utilization. The bacteria-derived PHB can be potentially used as an alternative to the conventional antibiotics in aqua-farming. Here we explored the effects of PHB on non-specific immunity of Litopenaeus vannamei. The L. vannamei was fed with baits containing PHB at different concentrations (0, 1.0%, 2.5% and 5.0%). The enzyme activities of the total antioxidant capacity (T-AOC), superoxide dismutase (SOD), peroxidase (POD) and lysozyme (LZM) in gill, hepatopancreas and serum were analyzed and compared among groups. The group with the best performance and the control group were selected for the ammonia stress test. After the NH4Cl treatment, we measured the concentration of malonaldehyde (MDA) and the expression levels of related genes in tissues by using real-time PCR. The results suggested that PHB affected the congenital immunity in the shrimp. As the concentration of PHB increased, the T-AOC activity in the experimental groups was first elevated followed by a decline. The activities of T-AOC in the serum, the hepatopancreas and the gill reached the maximum when the concentration of PHB was 2.5%, 2.5% and 1.0% respectively. The SOD activity in the gill and serum of shrimp fed with 5.0% PHB was significantly different from that in the control group. In the gill and hepatopancreas, the activity of POD and LZM peaked when the PHB concentration was 1.0% and 2.5% respectively. Compared with the control group, the POD activities of the experiment group supplemented with 1.0% and 2.5% PHB were 7.63-fold and 0.68-fold in the gill and hepatopancreas, and LZM activities were 1.88-fold and 1.18-fold, respectively. After the ammonia stress test, the shrimp fed with PHB showed lower MDA concentration than that without PHB, and the difference was significant in the serum (P<0.05). Furthermore, the expression levels of related genes were higher in the experimental groups compared to the control group. Our data indicated that PHB could improve non-specific immunity of shrimps.

Abstract:In the summer of 2013, there was an outbreak of skin ulcerative syndrome (SUS) in Apostichopus japonicus juveniles at a hatchery in Shandong Province. The symptoms included weak adhesion, rotten spines, viscera eversion, skin ulceration, and body autolysis. From the skin lesions of diseased juveniles we isolated a dominant strain HP130917A-1 with a median lethal concentration of 1.2×106 CFU/ml. This strain exhibited high pathogenicity and caused the same symptoms as SUS. The identification of this pathogen was verified using morphological observation, physiological and biochemical test, and 16S rDNA gene sequence analysis. The results demonstrated that HP130917A-1 was Vibiro alginolyticus and the causative pathogen associated with SUS. The microbial community structure was also analyzed using 16S rDNA gene sequencing, from which six major strains were found in the rearing system including V. alginolyticus, V. natriegens, V. parahaemolyticus, Bacillus subtilis, Bacillus thuringiensis and Staphylococcus equorum. V. alginolyticus was predominant among six major strains during the 50 days. On the 50th day of the experiment, the amount of V. alginolyticus reached the highest value of 1.31×105 CFU/ml in the substrates, which was considered as the pathogenic threshold of causing sea cucumber SUS. These results provided insights into the mechanisms of SUS and the health management of sea cucumber A. japonicus. Based on our findings we recommend healthy management strategies such as regular monitor of the amount of Vibrios, suitable frequency changing of the substrates, and the application of probiotics or herbal medicines.

Abstract:Heavy metals are considered as the most deleterious contaminants in the environment due to their non-degrading and bioaccumulative properties. Shellfish have been used as an indictor for the toxicity of Cd, Pb, and other heavy metals. However, there are very few studies about the effects of heavy metals on Scapharca broughtonii. The safety of the seafood largely depends on the level of heavy metals accumulated in the body, which is determined by the content of heavy metals in the aquaculture environment. Here qualitative and quantitative methods were conducted to study the acute toxicity of cadmium on S. broughtonii with different sizes, which serves as a sign of the seafood safety. We determined the semi lethal concentration (LC50) and the safety concentration (SC50) of cadmium in different time courses (24 h, 48 h, 72 h and 96 h), by SPSS18.0 statistical software (Prob-lg). The LC50 values of small S. broughtonii were 131.11, 41.40, 3.57 and 3.37 mg/L corresponding to the time courses above, and the SC50 value was 1.24 mg/L. In the medium S. broughtonii the LC50 values were 54.10, 9.46, 2.54, and 0. 50 mg/L, and the SC50 value was 0.09 mg/L. About the large S. broughtonii the LC50 values were 157.36, 38.13, 8.90, 3.46 mg/L and the SC50 value was 0.67 mg/L. These results demonstrated that the SC50 values of Cd2+ in S. broughtonii were higher than the water quality standard in aquaculture. The toxicity of Cd2+ was identified as moderate for small S. broughtonii, extreme toxicity medium S. broughtonii, and high toxicity for large S. broughtonii. There was hermetie effect on inorganrc cadmium for small S. broughtonii.

Abstract:To study the adaptive capability of Sipunculus nudus to three different types of sediments, we carried out a rearing experiment of S. nudus under the laboratory conditions. Treatments in quintuplicate were the sea sand (S-s), shrimp-pond sediment (S-sp) and fish-pond sediment (S-fp), respectively, with different oxidation reductive potential value, organic material content and different grain sizes. After sunlight exposure, all types of sediments were paved onto the bottom of the tanks (31 cm × 20 cm × 30 cm) to 10 cm thick, and the same water was put into each tank. Five individuals with mean weight of (2.58±0.23) g were stocked in each tank and cultured with a normal ration supply. DO content in the water was above 6.0 mg/L and no water change during the experiment. The results showed that the survival rate of S. nudus was up to 96%, 92% and 92% in S-s, S-fp and S-fp (P>0.05), respectively. Main component of the excrement of S. nudus was fine particles smaller than 0.4 mm, especially the 0.224 mm particles reached 47.70%, 85.95% and 69.99% in the treatments of S-s, S-sp and S-fp, respectively. At the end of the experiment, S. nudus presented growth to some extent in S-fp, while a little weight loss in other two groups. These results suggest that S. nudus has strong adaptive capability to the reductive condition and different grain size of sediment, while it has a higher need for the smaller size of particles (R<0.224 mm) for the restriction of its feeding organs. Meanwhile, the organic material of the sediment was a key factor to the growth of S. nudus, including the quality (source) and quantity of the food. Therefore, based on its strong adaptive capability to the different sediments, the culturing of S. nudus in the suitable ponds/beaches was an ecological-economical model with potential development.

Abstract:Lipase (EC 3.1.1.3) is one of hydrolases that specifically catalyzes the hydrolysis of triglyceride. It plays an important role in the food improvement, the health care, and the environment protection. The lipase of our interest here is produced by a marine microorganism YS2071 and has high enzymetic capability. Chitosan is a type of biological sources which possesses good biocompatibility and biodegradation. It is a natural, biological, and macromolecular polysaccharide, the solution of which is a non-toxic and functional gel. Therefore, chitosan is an excellent immobilization carrier. The separation and recycling of materials have been a challenge in the industrial production process. In this study we aimed to solve this problem by immoblizing YS2071 lipase on a chitosan microsphere. The properties of the immoblized lipase was compared to the free lipase to verify the immobilization method. The activity of the immobilized enzyme reached the maximum when the conditions were as below: 2% chitosan (m/v), 1% acetic acid concentration (v/v), 0.25% glutaraldehyde concentration (v/v), 12% sodium hydroxide concentration (m/v), crosslinking time 12 h, and 2 ml (1120 U) enzyme. The recovered activity of the immobilized lipase was 69.4%. The optimal temperature for the functions of the free lipase and the immobilized lipase was 40℃ and 45℃ respectively. The optimal pH for both the free lipase and the immobilized lipase was 8.0. It was also showed that immobilization obviously increased the stability of the temperature and pH. After 10-time reuse the recovered enzyme activity was still higher than 65%. The storage half-life of the immobilized lipase was 96 days while it was only 33 days for the free lipase. The free lipase and the immobilized lipase exhibited distinct stabilities in different organic reagents. These results suggested that the immobilized lipase might have great values in the industrial process.

Abstract:Here we conducted a feeding experiment to investigate the effects of Rhodotorula sp. C11 on the digestive enzyme activity and the immune response of juvenile Apostichopus japonicus, and to explore its potential use as probiotics in the aquaculture of sea cucumbers. Rhodotorula sp. C11 was added to the diets at the concentrations of 0 (control), 104, 105 and 106 CFU/g feed. The juvenile sea cucumbers were randomly allocated in 12 plastic tanks (100 L) with 50 individuals per tank. During the 30 day trial, all experimental sea cucumbers were fed one dose of diet per that weighed 5% of their body mass. At the end of the trial we measured the activities of the intestinal digestive enzyme and immunological parameters of the sea cucumbers. Data were analyzed with one-way analysis of variance (ANOVA) and Duncan's multiple comparison of the means with SPSS 19.0 software. A statistical difference was considered significant when P<0.05. It was shown that comparing to the control Rhodotorula sp. C11 at the concentration of 104 and 105 CFU/g feed significantly enhanced the activity of the intestinal trypsin, and at 104 CFU/g feed, Rhodotorula sp. C11 boosted the activity of amylase (P<0.05). Rhodotorula sp. C11 at the concentration of 105 CFU/g feed also increased the phagocytic activity in coelomocytes of sea cucumbers (P<0.05). Moreover, dietary Rhodotorula sp. C11 at the concentrations of 105 and 106 CFU/g feed significantly elevated the activities of lysozyme (LSZ) in the coelomic fluid, while that at 104 CFU/g feed increased LSZ activities in the coelomocyte lysate supernatant (CLS) respectively (P<0.05). Comparing to the control, the activity of total nitric oxide synthase (T-NOS) in the coelomic fluid was enhanced by Rhodotorula sp. C11 at 104 CFU/g feed, and the activity of this enzyme in CLS was elevated at 104, 105 and 106 CFU/g feed (P<0.05). Our results indicated that live yeast Rhodotorula sp. C11 could improve the activity of the intestinal digestive enzyme and activate the innate immune response of A. japonicus, therefore, it could potentially be used as an effective probiotic in sea cucumber farming.

Abstract:In this study we performed in vitro study on the pesticidal effects of 15 Chinese herbal medicines on the trophonts and theronts of ciliate Cryptocaryon irritans, including Betel nut (Areca catechu), Bitter ginseng (Sophora flavescens), Rhubarb (Rheum officinale), Cyrtomium rhizome (Cyrtomium Rhizoma), Radix scutellariae (Scutellaria baicalensis) and Wild chrysanthemum (Dendranthema indicum). We also explored the optimum temperature and salinity for the cyst rupture. At the concentration of 4.55 g/L, Betel nut could kill both the trophonts and the theronts of the ciliate, but Rhubarb and Wild chrysanthemum could only kill theronts. At the concentration of 9.09 g/L, both Bitter ginseng and Cyrtomium rhizome were able to kill the trophonts and the theronts. At the concentration of 18.18 g/L, Radix scutellariae, Toosendan fruit (Melia toosendan) and Fructus aurantii (Citrus aurantium) could kill the trophonts and the theronts, and Wild chrysanthemum could kill the trophonts. Other herbs could annihilate the trophonts and the theronts at much higher concentrations (45.45 g/L to 90.91 g/L), such as Astragalus root (Astragalus membranaceus), Heartleaf houttuynia herb (Houttuynia cordata), Isatis root (Isatis tinctoria), Chinese bulbul (Anemone chinensis), Honeysuckle (Lonicera japonica), Radix rehmanniae preparata (Rehmannia glutinosa), and Rhizoma coptidis (Coptis chinensis). These results suggested that Betel nut, Bitter ginseng, Rhubarb, Cyrtomium rhizome, Radix scutellariae, Toosendan fruit, Fructus aurantii, and Wild chrysanthemum might be more pesticidal than the other herbs, and hence they could be used to control the ciliate. Our study also revealed that the optimum temperature and salinity for the cyst rupture were 26℃and 20-30 respectively.

Abstract:Chemical dispersant has rapidly gained popularity in controlling unwanted oil spill in the aquatic environment, however, it exerts adverse effects on the aquatic organisms. The acute toxicity of chemical dispersant on fish, algae and zooplanktons has been widely investigated in previous studies. In the contrast, the acute toxic effects on shellfish remains unclear. In this study, we examined the acute toxic effects of chemical dispersant, dispersed 0 diesel oil (WAF) and chemically dispersed 0 diesel (CEWAF) on A. irradians. The test was performed within 96h, and the concentrations of chemical dispersant, WAF and CEWAF ranged from 0.50-3.00, 5.88-58.80 and 3.54-20.00 mg/L respectively. The LC50 values (within 95% confidence intervals) of dispersant in A. irradians were 1905, 1293, 1015 and 846 mg/L in the time courses of 24 h, 48 h, 72 h and 96 h respectively. The LC50 values of WAF were 36.57, 23.10, 14.99 and 11.31 mg/L corresponding to different time courses, and the values of CEWAF were 12.71, 8.51, 6.56 and 5.42mg/L respectively. As the time course increased from 24 h to 96 h, the median lethal concentrations (LC50) of chemical dispersant, WAF and CEWAF were decreased accordingly. The median lethal concentration and time course appeared to be highly correlated. The functions of LC50 (y) of dispersant, WAF and CEWAF against time (x) were y=12242x-0.583, y=564.37x-0.848, and y=89.987x-0.613 respectively. For the same exposure time, the order of the median lethal concentrations was dispersant > WAF > CEWAF, suggesting that the acute toxicity of CEWAF on A. irradians was higher than dispersant and WAF.

Abstract:Atrina pectinata is a large deepwater mollusk that is widely distributed in temperate and tropical ocean waters. The China costal line, from the Liaodong peninsula in the north to the Qiongzhou strait in the south, is a major habitat of Atrina pectinata. The provinces along the costal line included Liaoning, Shandong, Fujian and Guangdong, etc. This bivalve animal possesses high economic and medicinal values. The dried scallop of A. pectinata is large in size and has a tender texture and delicious taste. In recent years the overfishing has caused a rapid drop in the natural resource of Atrina pectinata and thus hindered the breeding in the aquaculture industry. The difficulty in the spawning inducement and the larval adhesion during culture has been the major issues in the large-scale production of A. pectinata seed. In the present study we explored different inductive methods and identified the optimal one to improve the fertilization rates and the embryonic development. Our study suggested that the combination of thermal stimulation (3℃ rise in the temperature) and sodium hypochlorite would neutralize the seawater and could be the optimal spawning-inducing method without noticeable impact on the fertilization rate and the embryonic development. To reduce the larval adhesion during the breeding, we adopted a lower breeding density and changed the incubation method. It was found that the larval adhesion could be effectively avoided at a lower larval density, and that at the density of 1 ind/ml the larval survival rate reached the maximum. Moreover, we also changed the cultural method for the A. pectinata larvae by equipping the cultivating pool with a surf pump. The surf pump generated a water flow inside the pool that prevented the larval adhesion and thus improved the larval survival rates. Our study provided a valuable tool for the large-scale production of the seed of A. pectinata.

Abstract:Frozen fish are usually less desirable than the fresh counterparts on the market. As a result, it has become a common issue that the frozen-thawed fish are disguised as fresh for a higher price. In this study the near infrared (NIR) spectroscopy was employed to separate the frozen-thawed fish from the fresh. One hundred and twenty prepared Sebastes schlegeli samples including 60 fresh and 60 frozen-thawed were scanned using a near-infrared spectroscopy system between 10000–4000 cm-1 wavenumbers. The working model was based on the fact that the average NIR spectra of fresh fish were distinctive from the frozen-thawed and possessed certain characteristics and fingerprint resistance. Principal component analysis (PCA) was used for the dimension reduction of the spectra data. The first two principal components (PCs) explained over 98% of variances in all the spectral bands. Clustering was performed and analyzed based on the first two PCs of all samples. The principal component score plot demonstrated that the fresh (above the X axis) and the frozen-thawed samples (below the X axis) were well separated, and that the distribution of fresh samples was dispersal. In order to improve the accuracy of prediction, the support vector machine (SVM) classification model was developed to differentiate the fresh fish from the frozen-thawed, based on principal component analysis scores. The score values of the first ten PCAs were used as the input variables of the SVM, and the penalty parameter c and kernel function parameter g were optimized. Ninety samples were used for building the SVM model. This model was then applied to predict the rest 30 unknown samples, and the prediction rate was 100%. These results suggested that the near infrared spectroscopy combined with principal component analysis and support vector machine could be used as a rapid, simple and reliable method to identify the fresh and frozen-thawed fish.

Abstract:Ancherythroculter nigrocauda has been popular for the delicate texture of the meat, and is a proper material of processed food due to its flat shape. Salting is a key step in the processing of A. nigrocauda. In this study we aimed to optimize the conditions of the salting process, including reducing the salting time, lowering the salinity and improving the safety of the products, and hence to provide theoretical guides for the large-scale production. Using A. nigrocauda as the raw material, and the salinity and the total volatile basic nitrogen (TVB-N) as the indicators, we optimized parameters such as the salt concentration, the salting temperature and the salting time in single factor experiments. In these experiments, the salt concentrations were 3%, 5%, 7%, and 9%, the salting temperatures were 5℃, 10℃, 15℃, and 20℃, and the salting time was 24 h, 48 h, 72 h, and 96 h. Then the response surface methodology (based on the Box-Behnken experimental design principle) was used to optimize the salting process of A. nigrocauda. The response surface methodology analysis was adopted to build two second order quadratic equations between the salinity, TVB-N and salting conditions including the salt concentration, the salting temperature and the salting time. Taking the convenience into consideration, we set the optimal salting parameters as follows: salt concentration 4.5%, salting temperature 7℃, and salting time 38 h. Under these conditions, the salinity of the product was 3.23% and the total volatile basic nitrogen was 32.35 mg/100 g. The validating test showed that the actual results were very close to the predicted results from the corresponding second-order quadratic equations, thus the model may effectively predict the salt concentration and the TVB-N values of salted A. nigrocauda products. This technology could be applied to the large-scale production with reduced salting time, lower salinity, and improved food safety. Furthermore, it could also be employed in the salting process of other kinds of fresh water fishes.