Abstract:Pyropia haitanensis is an important economic seaweed cultivated in the East China Sea. Its optimum growth temperature is about 20℃, and the extremely high temperature is about 29℃. P. haitanensis is vulnerable to disease due to high temperature or hostile epiphytic bacterial flora in the phycosphere. In this study, the thalli of P. haitanensis were co-cultured with Bacillus sp. WPySW2 which was proved to be probiotic to Pyropia at 20℃. However, the experiment was conducted at 28℃, an extremely high temperature to Pyropia species. The physiological indexes such as relative growth rate (RGR), activities of antioxidant enzymes (SOD and POD), contents of soluble proteins, free proline (Pro), malondialdehyde (MDA), and phycobiliproteins (phycorythrin, phycocyanin, and allophycocyanin) were detected. The results showed that:at 28℃, the RGR of co-cultured P. haitanensis was higher than the control at the beginning, while the difference became less significant when the co-culture process continued. Both the control and co-cultured samples rotted 4 days later, and the conditions of co-culture groups were worse. After co-culturing for 24 h, the activities of SOD and POD, and the content of MDA in co-culture samples were higher than the control. The contents of soluble proteins and free Pro were much lower than those in the control. The contents of phycobiliproteins in co-cultured groups were higher than the control. It revealed that at the high temperature such as 28℃, Bacillus sp. WPySW2 could promote the growth of P. haitanensis at the beginning of co-culture, however, when the co-culture process continued, the bacteria inhibited the growth and the physiological conditions of the algae. The results indicated the phycospheric bacteria could change the ecological functions when the environment changed.

Abstract:This study was to investigate the effects of four forms of zinc on growth performance, antioxidant capacity, intestinal performance and vertebrae mineral accumulation of juvenile hybrid grouper (Epinephelus fuscoguttatus♀×E. lanceolatu♂). The experimental diets were isonitrogenous and isolipidic diets by adding zinc sulfate (ZnSO₄), basic zinc sulfate[Zn₄(OH)₆SO₄], zinc glycine (Zn-Gly) and zinc hydroxymethionine (Zn-MHA), respectively. The zinc content of the four diets was 118.85, 116.92, 120.66 and 119.23 mg/kg, respectively. Three hundred and sixty individuals of grouper[initial average weight (11±0.12) g] were randomly divided into four groups with three replicates at a stock density of thirty, and fed with test diets for 8 weeks. The results showed that the weight gain rate and specific growth rate in Zn₄(OH)₆SO₄, Zn-Gly and Zn-MHA groups were significantly higher than those in ZnSO₄ group. The feed coefficient rate of fish fed Zn₄(OH)₆SO₄, Zn-Gly and Zn-MHA groups were significantly lower than that fed ZnSO₄ group. The survival rate was no different among the four groups. Hepatic malonaldehyde contents in Zn-Gly and Zn-MHA groups were significantly decreased compared with ZnSO₄ and Zn₄(OH)₆SO₄ groups. The activity of copper-zinc superoxide dismutase in the liver of fish fed with Zn-MHA was significantly higher than that in other groups. Compared to ZnSO₄ group, plica heights of foregut and midgut of fish fed with Zn₄(OH)₆SO₄, Zn-Gly and Zn-MHA were significantly increased. The muscle thickness of hindgut in the Zn-Gly and Zn-MHA groups was significantly higher than that in ZnSO₄ and Zn₄(OH)₆SO₄ groups. Vertebrae iron and manganese contents in fish fed with Zn-Gly were significantly higher than those in ZnSO₄ group. According to weight gain rate and hepatic copper-zinc superoxide dismutase contents, the relative bioavailability values of Zn₄(OH)₆SO₄, Zn-Gly and Zn-MHA, compared to ZnSO₄, were 119.15% and 110.90%, 118.43% and 113.58%, 122.45% and 130.84%, respectively. In conclusion, in the aspects of growth performance, activity of hepatic SOD and the iron accumulation in the vertebrae, Zn₄(OH)₆SO₄ is better than ZnSO₄. However, Zn-Gly or Zn-MHA as organic form of zinc can impove growth performance, oxidation resistance, and intestine development compared to ZnSO₄.

Abstract:Four phenylpropanoid antialgal compounds (1-4) were successfully isolated from Gracilaria lemaneiformis through a combination of solvent soak, liquid-liquid extraction, silica gel column chromatography and repeated preparative thin-layer chromatography. On the basis of the spectral data, the compounds were identified as benzene-1,2-propanoic acid (1), gossonorol (2), 7,10-epoxy-ar-bisabol-11-ol (3), and p-hydroxyphenylethanol (4). These 4 compounds were isolated from marine macroalgae for the first time. Further, a quantitative relationship between the inhibition of algal growth and the concentration of each phenylpropanoid antialgal compound was determined and important parameters for future practical HAB control, e.g. EC_{50-96 h}, were also obtained. The results indicated that isolated compounds 1-4 possessed selective antialgal activity against the growth of several red tide microalgae (Amphidinium carterae, Heterosigma akashiwo, Karenia mikimitoi, Phaeocystis globosa, Prorocentrum donghaiense, and Skeletonema costatum). Their antialgal activity against the tested red tide microalgae has not been previously reported. Among them, benzene-1,2-propanoic acid (1), gossonorol (2) and p-hydroxyphenylethanol (4) showed more extensive antialgal activities against the tested red tide microalgae. Furthermore, benzene-1,2-propanoic acid (1) against A. carterae, H. akashiwo and P. globosa; gossonorol (2) and p-hydroxyphenylethanol (4) against H. akashiwo and P. globosa; and 7,10-epoxy-ar-bisabol-11-ol (3) against H. akashiwo and K. mikimitoi possessed better application potential than potassium dichromate as a characteristic antialgal agent against these red tide microalgae.

Abstract:To investigate and obtain the best medium formula and fermentation conditions of an antagonistic strain WM-1 against Aeromonas hydrophila, we used A. hydrophila as the index bacteria of the antibacterial. The activity of strain WM-1 was measured by Oxford cup test. Single factor experiments and orthogonal experiments were employed to optimize the liquid medium compositions and fermentation conditions of WM-1. The data showed that the optimum medium included 1.0% soluble starch, 1.5% beef extract, 0.05% K₂HPO₄·3H₂O and 0.07% MgSO₄·7H₂O; and the optimal fermentation conditions were initial pH 7.5, culture temperature 30℃, fermentation time 48 h, medium volumes 20%, rotating speed 210 r/min. Under the optimum conditions, the inhibition zone of WM-1 reached (22.5±0.50) mm, which was 40.6% higher than that under non-optimized conditions. These results provide a theoretical basis for the biocontrol of A. hydrophila.

Abstract:Marine ranching is an ecological system engineering with many functional areas. The ecological environment and food web structure vary from functional area to functional area. Study on food web structure of different functional areas contributes to knowing ecosystem differences among functional areas. Stable isotope techniques were applied to the analysis of food web structure in different functional areas in Nan'ao Zhelin Bay Marine Ranch, where samples were collected for fishery resources and environment investigation. The results showed that 78 species were collected in the marine ranching, the δ¹³C values of consumer ranged from -19.94‰ to -13.62‰, the δ¹⁵N values ranged from 8.78‰ to 15.29‰ and trophic level ranged from 1.73 to 3.64. Compared with other functional areas, the artificial reef area possessed more biological resources and complex structure of food web. In addition, there is broader isotopic resource and higher trophic redundancy in macroalgae area while the ecological niche of shellfish area was narrower and nutrient distribution was more concentrated. By comparison of the ecosystem stability in different functional areas, the artificial reef area is best while the macroalgae area is poor.

Abstract:This study investigated the etiology of Oncorhynchus mykiss that suffered fulminant death in Shimian of Sichuan. General observation, virus isolation, pathogenicity tests, multiple RT-PCR assay and histological examination were performed to explore its causes, and to indentify the pathogen WZ160509 in which the major structural protein VP2 was amplified and analyzed. Principal symptoms included darkened body, abdomen distension, yellow mucoid fluid fecal casts from anus. Internally, no food was found in digestive tract and enteritis, pale liver and kidney were observed. The filtrated homogenate was also inoculated into the O. mykiss gonad cell line cells, and the typical cytopathic effect was formed after three blind passages. The result of artificial infection test showed that IPNV could cause 90% death rate, and the injected trouts displayed similar clinical symptoms as the fish that was naturally infected. Multiple RT-PCR assay was performed to detect the presence of the virus from the fish naturally infected, the fish artificially infected and the infected cells, and all the results showed IPNV-positive, and the homology analysis, in which the test sample mixed the main structural protein VP2 gene and genomic U.S. isolates 1 type, showed the highest homology between WZ160509-VP2 and IPNV-VP2 (AY026345) and the sequence identity was 95.8%. Histopathologic analysis, pancreas and liver showed degeneration and necrosis. A mild inflammation was observed in glomerular. Besides, increased capillary permeability and red floccule proteins were also observed in capsular space. Renal tubule showed vacuolar degeneration and proteinuria. All the results show the isolated virus is IPNV.

Abstract:Human activities including overfishing, environmental pollution and climate change affect the dynamics and stability of marine fish communities. In order to deeply explore the community structure and its change of fish assemblage, multivariate statistical analysis and structural redundancy analysis were used to examine the spatial structure and structural redundancy of fish community based on the data from the bottom trawl surveys in spring and autumn in 2011, 2013-2016 in the Haizhou Bay and its adjacent waters. The results showed that the fish assemblage could be divided into two fish communities, i.e. the northern community and the southern community in spring and autumn in the waters. Typifying species were composed of Enedrias fangi, Liparis tanakae, Lophius litulon and Hexagrammos otakii for the northern community and Larimichthys polyactis, Cynoglossus joyneri, E. fangi and Conger myriaster for the southern community in spring. Typifying species included Chelidonichthys spinosus, Saurida elongate and C. myriaster for the northern communities, and comprised C. joyneri, Collichthys lucidus, Miichthys miiuy, Chaeturichthys stigmatias, L. polyactis and Johnius belangerii in the southern community in autumn. There was one response unit for the fish assemblages in spring and autumn, and the structural redundancy of fish community was low. The composite species in the response unit was similar to the typifying species in the northern and southern fish communities, indicating that the spatial patterns of fish community in spring and autumn in the Haizhou Bay were determined by a few species. The number of substitute species was few, and the stability of fish community was low in the Haizhou Bay and its adjacent waters.

Abstract:To evaluate the feasibility of essential oils as natural preservatives in extending the shelf life of chilled large yellow croaker, the antimicrobial efficacy of 14 essential oils against the dominant spoilage bacteria from large yellow croaker (Larimichthys crocea) during chilled storage at 4℃ was investigated. The dominant spoilage bacteria were isolated from skin, body cavity, gill and intestine of large yellow croaker, and identified by the sequence similarity analysis of the 16S rDNA genes and physiological and biochemical test. The paper disc diffusion method and microbroth dilution technique were employed for the determination of antimicrobial activity of 14 essential oils. Sensory acceptability of fish treated with different quantities of essential oils were evaluated using a nine-point hedonic scale ranging from 1 (most disliked) to 9 (most liked). The mode of action of Litsea cubeba oil against spoilage bacteria was studied by scanning electron micrograph, measurement of release of intracellular lactate dehydrogenase (LDH), and 260 nm absorbing material. After dipping in a solution containing 4 μL/mL L. cubeba oil, the total microbial load, H₂S- producing bacteria, total volatile bases nitrogen(TVB-N), and histamine content of refrigerated large yellow croaker fillets as a function storage time were determined. The results showed that a total of 6 strains of bacteria were identified as four strains of Shewanella spp., one strain of Brochothrix thermosphacta and one strain of Aeromonas sobria. The 14 essential oils showed different antimicrobial activity against spoilage bacteria isolates, and cinnamaldehyde had thse highest activity with a minimum inhibitory concentration(MIC) of 0.125 μL/mL, followed by eugenol, thymol, citral, Cymbopogon citratus and L. cubeba oil, with MIC ≤ 0.5 μL/mL. The flavours of large yellow croaker fillets treated with eugenol, thymol, citral, C. citratus and L. cubeba oil were found to be acceptable. L. cubeba oil can disrupt the cytomembrane of spoilage bacteria isolates and cause the leakage of protease and nucleic acid. Dipping fish fillets in a solution of 4 μL/mL L. cubeba oil significantly reduced the total microbial load, H₂S-producing bacteria, TVB-N, and histamine content. Eugenol, thymol, citral, C. citratus, and L. cubeba oil showed high antimicrobial activity against the dominant spoilage bacteria isolates from chilled large yellow croaker, and had no adverse effects on the organoleptic properties of the fish fillets. Therefore, it can be concluded that essential oils had the potential to be used as natural preservatives to enhance the shelf-life of seafood during chilled storage.

Abstract:Short arm octopus, Amphioctopus fangsiao, is widely distributed along the coast of China, and also is one of the important commercially explored cephalopod species in China. Based on 393 samples of A. fangsiao collected along the coast of China, including the Yellow Sea, East China Sea and South China Sea during October to November in 2015, the variation of ten standardized beak morphometrics was studied among the different areas and the discriminant analysis was also established based on the beak morphology. The results showed that the body size of A. fangsiao located in Yellow Sea and East China Sea was similar, and the individuals in South China Sea were smaller than other areas; the standardized beak in South China Sea was also smaller than other two areas. ANOVA test showed that the beak morphometrics in East China Sea and Yellow Sea had no significant difference except for lower beak wing (P>0.01), and beak morphometrics in South China Sea had significant difference compared to other two areas (P<0.01). Principal component analysis suggested that the lower beak mophometrics represented first component factor, and upper beak morphometrics represented the second and third component factors for all the individuals from three different areas. Six beak morphometrics were selected for the stepwise discriminant analysis, and the correct classification rate was over 80% for three different areas. The result of classification tree analysis showed that lower beak morphometrics (lower hood length and lower wing length) can be a good criterion for quick identification of the octopus from different areas. In conclusion, this study has confirmed that the beak morphology has different patterns in different areas due to the varied environments, and also showed that beak is a suitable criterion for identifying the population variation for cephalopods.

Abstract:Spanish mackerel is an economic species in the Yellow Sea and Bohai Sea, which occupies an important position in marine fishery, and it is important to evaluate its biomass and stock status. However, the fishery lacks relevant data in China, which causes the difficulty in fisheries evaluation and management. Among them, the uncertainty of catch data is especially noticeable, and its variation in values and trends is often measured with the observation error and bias. This study evaluated the performances of six data-limited management procedures which belong to two categories:output control and input control, and we focus on their response and sensitivity to observation error and bias of catch data. Our results indicate that output control MPs including CC4、SPMSY and AvC are more sensitive to observation error and bias, while DD showed slight response to observation error and bias, which is more suitable for managing mackerel fishery. And the sensitivity analysis showed that output control MPs are sensitive to the OM parameters including B_MSY/B₀, hs, F_MSY/M and F_MSY. Relatively, the input control including minlenLopt1 and curE75 is not sensitive to the uncertainty of catch data and OM parameters. In general, we can conclude that the input control MP shows minor responses to the catch error and catch bias, whereas the output control MP shows different responses to the catch error. And according to the MSE, curE75 has the best balance between the exploitation and protection of mackerel fishery.

Abstract:In order to discuss the temporal and spatial variations of zooplankton community in coastal East China Sea and based on the data obtained from 3 cruises of zooplankton surveys conducted in the coastal waters of East China Sea in May, August and December of 2013, the species composition, biomass and abundance, dominant species and ecological groups were investigated. The results showed that a total of 108 species belonged to 15 groups in 7 phyla, including undefined species, together with 14 classes of pelagic larvae. The 7 phyla including Cnidaria, Ctenophora, Annelina, Mollusca, Arthropoda, Chaetognatha and Urochordata. Copepoda and Medusae were the most dominant groups in numbers of species and abundance. The most dominant group of zooplankton was Copepoda, including 47 species accounting for 43.52%. Medusae ranks second with a total of 19 species, accounting for 17.59%. There was a considerable seasonal variation in species of zooplankton in the coastal waters of East China Sea. In summer, the species richness was significantly higher than spring and winter. The linear relationship of species and latitude was negative correlated in May, August and December, which reached an extremely significant level. The whole area average abundance and biomass of zooplankton of coastal waters in East China Sea changed seasonally. Both the average abundance and biomass in winter were the lowest, the average biomass was the highest in summer, and the average abundance was the highest in spring. The community can be divided into 6 ecological groups according to the tolerance of zooplankton in hydrological environment and the differences of living areas, which were coastal species of low salinity, wide temperature and salinity species, high temperature and salinity species, warm coastal species, warm water species and cosmopolitan species. In spring and winter the coastal species of low salinity, wide temperature and salinity species accounted for absolute advantage in the southern Yellow Sea coastal waters, but warm water species were in higher proportion in summer. However, in Yangtze River estuary and adjacent waters, the warm water species were the dominant community in spring, summer and winter. What's more, in the central and southern coastal waters, warm water species play a dominant role in spring and winter. But the high temperature and salinity species, cosmopolitan species community was obviously dominant in summer. Calanus sinicus was the only common dominant species in these seasons. Dominant species changed more obviously, and the dominant species turnover rate was 90.9% from spring to summer, which was 50% from summer to autumn.

Abstract:This study was designed to research the response of free-living conchocelis growth and sporangium branches formation stage of free-living conchocelis of Pyropia haitanensis to agaro-oligosaccharide. After being treated with agaro-oligosaccharide, the net photosynthetic rate of free-living conchocelis of P. haitanesis was measured by liquid phase electrode; the concentration of H₂O₂ in the medium was determined by the dimerization of (p-hydroxyphenylethyl) acetic acid; the floridoside content was detected by LC-MS; the H₂O₂ related genes (Phrboh, PhSOD) and the floridoside synthesis related genes (Phnho1, Phgpdh, Phtps) expression was detected by real-time PCR; the number of sporangium branches was examined by microscopy. The results showed that the agaro-oligosaccharides can stimulate a series of responses of free-living conchocelis of P. haitanesis. These responses include increased photosynthetic rate; increase the content and biosynthesis of photosynthetic products of floridoside; the release of H₂O₂ continues to increase which was associated with the activation of two enzymes associated with H₂O₂ gene Phrboh and PhSOD. In addition, agaro-oligosaccharides can also promote the development of free-living conchocelis of P. haitanesis. On thirtieth day of culture, the sporangium branches formation rate of agaro-oligosaccharides treatment group reached 59%, significantly higher than the control group 46%. In conclusion, agaro-oligosaccharide can increase the free-living conchocelis of P. haitanesis photosynthetic rate and photosynthetic products, and can increase the expression of H₂O₂ synthesis enzyme to induce the release of ROS. Meanwhile, agaro-oligosaccharides can promote the reproduction of free-living conchocelis of P. haitanesis.

Abstract:The nutritional components and quality of muscles from Epinehelus moara, E. lanceolatus and hybrid "Yunlong grouper" were investigated and evaluated to provide basic data for the nutritional evaluation of their germplasms and the development of compound feed. The composition and content of water, protein, crude fat, ash content, amino acids, fatty acids and 10 mineral elements in the muscles of three groupers were measured by conventional methods, according to the national standard. The crude protein contents in the muscles of E. moara, E. lanceolatus and "Yunlong grouper" were 19.6%, 18.4% and 19.4% respectively. The total quantity of amino acids, essential amino acids, essential amino acid index and the flavour amino acids of these three groupers were (15.54%, 14.72%, 15.99%), (6.86%, 6.41%, 7.04%), (75.19, 74.93, 77.96) and (5.57%, 5.3% and 5.73%) respectively. The fat content in the muscle of three grouper is 4.2%, 10.1% and 4.5% respectively; the fat are rich in fatty acids variety and polyunsaturated fatty acids, and the ratio of polyunsaturated fatty acids/total fatty acids is consistent with ideal fatty acids. There are abundant mineral elements in the muscles of three groupers; five major elements (K, Ca, Na, Mg and P) and five kinds of trace elements (Fe, Mn, Cu, Zn and Se) have been detected. Among them, the contents of Na, K and Cu in hybrid "Yunlong grouper" are slightly higher, and the contents of other kinds of mineral elements are among parents. The research shows that E. moara, E. lanceolatus and "Yunlong grouper" contain all kinds of amino acids, suitable ratios of essential amino acids, a lot of unsaturated fatty acids and abundant mineral elements. Thus, the three groupers are excellent seawater breeding varieties with high edible value. In addition, "Yunlong grouper" shows some superiority in some nutritional indicators compared with their parents.

Abstract:An 8-week feeding trial was conducted to evaluate the effects of different lipid sources on growth performance, body composition, the serum biochemical indices, fatty acids composition and antioxidant capacity in juvenile yellow catfish. Four isoproteic and isolipidic diets were formulated to contain different lipid sources:coconut oil, perilla oil, sunflower oil, fish oil+sunflower oil (1:1) mix oil, respectively, on the basis of adding soybean oil. Each diet was randomly assigned to feed three replicate groups of juvenile yellow catfish whose initial body weight was approximately (1.52±0.00) g. The results showed that the different dietary lipid sources didn't have significant influence on final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR) and survival rate (SR), but had significant differences in feed conversion ratio (FCR). The SR of all groups was more than 95%. The hepatosomatic index (HSI) and condition factor (CF) showed significant differences among all groups. However, they didn't have significant differences in the viscerosomatic index (VSI) and intraperitoneal fat ratio (IPR). The HSI and CF of fish fed fish oil+sunflower oil (1:1) mix oil were significantly higher than other groups. The moisture, the crude protein, the ash content were not significantly affected by lipid sources. But the crude lipid of fish fed coconut oil, which was 10.51%, was significantly higher than other groups. Fatty acid composition of muscle and liver in fish generally reflected the composition of the diet. Furthermore, the different dietary lipid sources had significant differences in the fatty acid composition in the muscle and liver. The saturated fatty acid (SFA) content of fish fed coconut oil was the highest, the α-linolenic acid (ALA) and n-3 polyunsaturated fatty acids (n-3 PUFA) content of fish fed perilla oil the were the highest, the linoleic acid (LA) and n-6 polyunsaturated fatty acids (n-6 PUFA) content of fish fed sunflower oil were the highest, and the fatty acid composition of fish fed fish oil+sunflower oil (1:1) mix oil is more balanced. No significant difference was found among all treatments in total protein (TP), albumin (ALB), globulin (GLOB), A/G, aspartate aminotransferase (AST), total cholesterol (CHOL), triglyceride (TG), blood glucose (GLU) and creatine kinase (CK) in the serum. While the activities of sulyperoxide dismutase (SOD), malondialdehyde (MDA) and glutathione S-transferase (GST) in liver were significantly influenced by lipid sources. Fish fed coconut oil had significantly higher activity of SOD as well as GST, but lower content of MDA, in serum than the other treatments. These results indicate that coconut oil, perilla oil, sunflower oil and fish oil+sunflower oil (1:1) mix oil can be used as dietary lipid sources of yellow catfish, on the basis of adding soybean oil. And the fatty acid composition of fish body basically reflected the fatty acid composition of diet and the essential fatty acids of freshwater fish were LA and ALA.