Abstract:The species composition of coccolithophores was investigated based on the survey in shelf waters of the East China Sea during May 2007. By utilizing the scanning electronic microscope, we reported the species list of coccolithophores in this region and photographically demonstrated these species collected in the sampling sites. The results showed that a total of twenty-three species were recorded and affiliated to nine Families, four Orders. Most of these species were heterococcolithophores, and others were holococcolithophores. According to the frequency of occurrences, species of Order Syracosphaeraceae were the most abundant forms, especially the Genus Syracosphaera, with seven species in this group, accounting for more than thirty percent of the total species covered by this study. Emiliania huxleyi (Lohmann) Hay & Mohler and Gephyrocapsa oceanica Kamptner were found in all of the samples and three types of E. huxleyi were examined, including type A, type B/C and type C. Four species of coccolithophores were first recorded from the coastal waters of China Seas. They were: two heterococcolithophores of Family Syracosphaeraceae, Syracosphaera histrica Kamptner and Syracosphaera marginaporata Knappertsbusch; two holococcolithophores of Family Calyptrosphaeraceae, Calyptrolithophora papillifera (Halldal) Heimdal and Corisphaera strigilis Gaarder. Their morphological characteristics were also described in this paper. The physico-chemical environments in the offshore seawaters of East China Sea were strongly influenced by the current of Kuroshio, providing ideal habitats for the rapid growth and reproduction of coccolithophores, and sustaining relative more species of coccolithophores in these regions.

Abstract:Research on basic biology of yellow-fin tuna Thunnus albacares is essential for its stock assessment. In this paper, some biological characteristics of T. albacares were preliminarily studied based on the long-line catches in the South Pacific Ocean near Solomon Islands from August to October 2010. The results are shown as follows: (1) The fork length (FL) ranged from 47.5 to 166.5cm with an average of 112.7 cm, and two dominant groups were found at 80.0 ~ 90.0 cm and 100.0 ~ 140.0 cm (75%); The raw weight (RW) varied between 2.0 and 72.0 kg with dominant groups at 5~10kg and 15~40 kg (68.6%), and the average weight was 26.5 kg. However, body size differed greatly between female and male T. albacares . (2) The relationships between RW and FL and dressed weight (DW) were RW=1.159×10-5FL3.070 and RW=1.118DW+0.684 respectively. (3) The sex ratio of female to male was 1∶1.2, but there were significant differences between size-different groups (χ2=1 093.386，P<0.001). The male was dominant in number when FL was over 140 cm. (4) Gonad samples were mainly at stage Ⅱ (about 50%). The length at 50% maturity (FL50%) was estimated to be 113.4 cm and 34.0% of individuals at greater FL had achieved stageⅤ~Ⅵ gonad maturity, indicating that the stock near Solomon Islands was in spawning period during the survey. (5) Based on the stomach content analysis, we found that T. albacares mainly preyed on fish (67.5%), cephalopods (18.0%) and crustaceans (14.5%), and the empty-stomach ratio was about 51.6%. Significant differences in feeding levels were found between FL groups (χ2=400.782，P<0.001).

Abstract:Partial sequences of mitochondrial COⅡ gene in 12 octopus species in 2 genus of Octopodinae, were amplified and sequenced to investigate the phylogenesis of Octopodinae in China coastal waters. Multiple biological softwares were employed to analyze the sequence variations and nucleotide composition. Genetic distances were calculated by Kimura-2-parameter method and phylogenetic trees were constructed by both NJ and UPGMA method with more cephalopoda sequences available in GenBank. Results showed that COⅡ genes of octopus were rich in A and T nucleotide bases, as most other mitochondrial genes represent. The sequences showed an obvious anti-G bias. The most variable sites among species lay in the last site of codon of the coding region, leading to less amino acid variation. Genetic distances calculated between species were 0.000 0~0.232 3, and most of them were between 0.140 0 and 0.200 0. The constructed phylogenetic tree suggested that the 12 Octopus species were from two groups: long-arm group represented by Octopus vulgaris and short-arm group represented by O. aegina, which again supported the non-monophyletic of Octopus genus. The Octopus genus can be divided into two or more distant genus according to this study. The taxonomic position of some Octopodinae species was also discussed, and the potential application of COⅡ gene in cephalopoda classification and phyletic evolution was suggested. The results of this study may help understanding the taxonomy and phyletic evolution of Octopodinae species in China coastal waters and contribute to better exploitation and farming of these precious species.

Abstract:Based on zooplankton samples collected in Antarctic krill Euphausia superba Dana fishing grounds adjacent to the South Shetland Islands (CCAMLAR subarea 48.1) and South Orkney Islands (CCAMLAR subarea 48.2) in the Antarctic peninsular region during the period of January 23 to February 13, 2010, the abundance density, length distribution and development stage composition of Thysanoessa macrura G. O. Sars were studied. Samples were collected by two types of plankton nets, one was vertically towed plankton net with 330μm mesh size, and the other was horizontally towed surface plankton net with 500μm mesh size. Sea surface temperature (SST) ranged from 0.37 ℃ to 2.49 ℃, with a mean of 1.58 ℃ ; surface salinity ranged from 32.91 to 34.32, with a mean of 33.88. T. macrura was found in most of the survey area; vertical sample showed that the mean density was 261.6 ind/1000m3 in subarea 48.1 and 391.5 ind/1000m3 in subarea 48.2, and the density was positively correlated to SST (P=0.04). T. macrura was composed of individuals at all development stages from CII to adults and dominated by furcilia. The range and mean total length of furcilia, juvenile and adult were 2.74～6.80 mm, 5.15 mm; 6.81～16.20 mm, 8.15 mm and 15.40～20.70 mm, 17.98 mm respectively. The growth rate at the various stages of furcilia ranged from 0.013～0.064 mm/d; no significant difference was found between the two subareas (P=0.37), and the global mean was 0.040 mm/d. The spawning season of T. macrura was estimated to be at the end of September to October in subarea 48.1 and at the beginning of October to mid November in subarea 48.2. T. macrura appeared more frequently in the surface towed net both in terms of station and in terms of specimen, indicating that the surface towed net can be an effective supplement to the vertically towed net in study of the spatial distribution and growth of krills in general.

Abstract:In order to understand the interaction between Bullacta exarata and sedimental environment, population of B.exarata and sediment characteristics were investigated at the typical distribution area of the Yellow River estuary in August, 2011. The results were as follows: (1) B. exarata was mainly distributed in mudflats with median particle diameter φ (Mdφ) ranging from 3.73~5.25; and the sediment types were composed of silt, salt-sand and sand-salt. (2) The average organic content and Chl-a concentration in surface sediment of the south intertidal zone was 1.39% and 2.65μg/g, which was significantly higher than in the north of the estuary with an average organic content of 0.54%and Chl-a concentration of 1.48μg/g. (3) The average population density was 16.7ind/m2,which was significantly higher in the south intertidal zone than in the north of the estuary with the average population densities of 0.6ind/m2. The relationship between population density (x) and average shell length (y) could best be expressed as the linear equation:y=-0.180 1x+19.184, R2=0.776．B. exarata body size and population density was inversely proportional; the higher the population density, the smaller the body size. (4) Taylor' power law, Iwao's patch regression and Morisita index analysis results showed that the spatial pattern of B. exarata population in the estuary belonged to the clumped and negative binomial distribution theoretically. (5) There were positive relationships between the density of B. exarata and organic content or Chl-a, suggesting that food source might be one of the main limiting factors for the distribution of B. exarata population.

Abstract:Phytoplankton at inshore area of Laoshan and Liuqing River Bay of Qingdao were investigated in May and August, 2012. There were 36 species belonging to 23 genera of phytoplankton collected during the survey in May, and the total number of phytoplankton was 85.26×103～720.16×103cell/m3. An outbreak of Noctiluca scintillans was observed in May, when its cell number was more than 80% of the total cell count. The diversity index was influenced by N. scintillans, and the cell abundance was also low. In August, Fifty-four species belonging to 30 genera of phytoplankton were collected during the survey; the total number of phytoplankton was 43.00×103~1 116.27×103cell/m3. In August, phytoplankton was more diverse in survey areas, and the cell abundance was lower. Clustering analysis showed that the similarity of the phytoplankton community was more than 60% in May, and more than 50% in August. The cell abundance of phytoplankton at inshore area of Laoshan was more than that in Liuqing River Bay, while the diversity of the former was lower than the latter. Average cell abundance showed a negative correlation with N/P (r=-0.81, P<0.05), while the mean diversity showed a positive correlation with N/P (r=0.98, P<0.05). It is concluded that the key limiting factor affecting the cell abundance and diversity of phytoplankton was the inorganic nitrogen.

Abstract:The activity of four digestive enzymes in larval and juvenile Hexagrammos otakii (0~100d) was studied. Different trends of variation were observed for the four digestive enzymes duirng the early developmental stages. The activity of pepsin gradually increased with growth and development of the fry; the activity of trypsin initially showed a gradual upward trend, though declined after reaching its peak at 20d, and then increased again after 40d and reached its maximum at 60d. The activity of amylase decreased after reaching the maximum at 20d and maintained smooth change. The activity of lipase reached a minimum at 5d and gradually increased after 40d.

Abstract:Full-length cDNA encoding membrane progestin receptor alpha gene (mPRα) was firstly cloned from half smooth tongue sole Cynoglossus semilaevis Günther by homology cloning and RACE-PCR analysis. The length of complete cDNA sequence of mPRα gene was 1 319 bp. Sequence alignment of deduced amino acid of tongue sole mPRα and amino acid of other species showed that there were seven transmembrane domains. The rooted phylogenetic tree was constructed by the neighbor-joining method of MEGA 4.0, and the identity of tongue sole mPRα with other representative sequences was analyzed by ClustalX. The results indicated that the tongue sole mPRα was clustered together with mPRα of other fish. The identity was 94%, 93% and 90% when compared with Southern flounder Paralichthys lethostigma, Atlantic croaker Micropogonias undulates and Japanese medaka Oryzias latipes, respectively. In contrast, identity among the mPRα of tongue sole and that of human Homo sapiens and cattle Bos taurus was low, only 53%. A semi-quantitative RT-PCR was developed to measure mRNA expression levels of mPRα gene of female tongue sole. Tissue expression analysis showed that mPRα mRNA was expressed widely in tongue sole, although the expression level was not homogeneous. mPRα transcripts were highly abundant in brain, kidney, spleen and ovary, less abundant in liver, stomach and muscle.

Abstract:Five marine fish pathogens, including Vibrio anguillarum, Aeromonas salmonicida, V.parahaemolyticus, V. harveyi, Shewanella putrefaciens were previously isolated and identified. In this study,virulence of these pathogens were determined by artificial infection experiments. The results showed that LD50 value of the five bacteria against turbot Scophthalmus maximus were 102~107CFU/fish. The polyclonal antibodies against them were produced from five New Zealand white rabbits respectively,and the titers of the polyclonal antibodies were 1∶2 048 000, 1∶16 000, 1∶16 000, 1∶1 024 000, 1∶128 000 respectively. The polyclonal antibodies were used in indirect ELISA as primary antibody, and the goat anti-rabbit IgG-HRP was used as a secondary antibody. The indirect ELISA method of rapid detection of five pathogens was developed. The sensitivity of the serum was tested, and the lowest concentrations of five pathogens that can be detected were 104, 108, 107, 105, and 106 cell/ml, respectively. Obvious cross reactions were present between three strains of vibrio and the antisera. By using the developed indirect ELISA method, 13 bacterial strains isolated from the infected fish were detected. One strain from the flounder and black rockfish Sebastodes fuscescens samples in the area of Jiaonan, Shandong Province, was positive for S. putrefaciens and two were positive for V. harveyi; one strain from Cynoglossus semilaevis in the area of Wudi, Shandong Province, was positive for both V. parahaemolyticus and V. harveyi. This result is consistent with the result of 16S rDNA method.

Abstract:The water purification process includes filtration of arc screen, strong aeration, biological filtration and UV sterilization in the recirculating aquaculture system (RAS). The pathogens of skin ulceration, Vibrio splendidus and Vibrio harveyi were selected to be the indicator bacteria for study on bacterial distribution and extermination in RAS of flatfish Cynoglossus semilaevis. Pathogens were found in the feed residues, organic sediment on the tank wall and each instrumental compartment of RAS. Unhealthy fish seedlings and tools used in the cultivation could also bring pathogens into the culture system. Extermination trials illustrated that the filtration of arc screen, strong aeration and UV sterilization were important in the elimination of bacteria. The disinfection rate of pathogens in the organic sediment on tank wall was higher than 90% by washing with KMnO4 at a concentration of 25×10-6 mol/L for 1.5min. While the disinfection rate of pathogens on the body surface of the flatfish reached 94.49% by being soaked in H2O2 at a concentration of 100×10-6 mol/L for 10min. This is the first report on the distribution and extermination of pathogenic bacteria in RAS of flatfish, which will provide theoretical data and reference for the management of RAS.

Abstract:Experiments were conducted to evaluate the effects of different salinity on growth, non-specific immunity and antibacterial activities of sea cucumber Apostichopus japonicus. The results showed that: (1) The survival rate of treatment A (salinity 16) was reduced to 66.7% (P<0.05), which was significantly different with other treatments and the control (P＞0.05). During the experiment, no mortality of sea cucumber was observed among the treatments at salinity of 22 and above. The specific growth rate of sea cucumber showed significant difference between treatments and control (P<0.05). At salinity of 20 and below, sea cucumber showed a negative growth. (2) The activities of superoxide dismutase (SOD), lysozyme (LZM) and antibacterial activity decreased with time, that is, from the maximum values at the beginning of the experiment to the minimum values at 30 d. We conclude that low salinity stress can significantly affect the survival and growth of sea cucumbers by reducing the immunity and increasing the susceptibility to pathogens, resulting in disease and mortality.

Abstract:In recent years, more and more nucleic acid based molecular biotechnologies were established and applied in the disease diagnosis, health evaluation, epidemiological surveillance, genetic breeding, environmental analysis, and other aspects of aquaculture. Good quality and high quantity of nucleic acid to be preserved and extracted from the samples are the prerequisites of these technologies. Sample collection and preservation methods are the key elements to ensure the successful application of the technologies. Currently, most studies use fresh material or ultra-low temperature preserved sample for RNA extraction. However, these methods are very difficult to be applied to aquatic animals, especially for field-collected samples. This study aimed to find a convenient and effective preservation solution for field-collection. Muscle tissues were taken from Litopenaeus vannamei and preserved in the ammonium solutions at different saturation and different pH at 28 ℃ for different time periods. Comparison of the RNA extraction showed that preservation solution of saturated ammonium sulfate and saturated ammonium acetate had good effect. The saturated ammonium acetate at pH 6.0 (A3) and the saturated ammonium sulfate at pH 5.2 (S3) with 25mmol/L sodium citrate and 20mmol/L ethylene diamine tetraacetic acid(EDTA) had a significant effect on tissue preservation, by comparing gene copy number by total RNA extraction, gel electrophoresis, and RT-PCR. We successfully extracted a large amount of genomic RNA, and quantitative results showed that the 18S rRNA copy number reached 105 for per milligram tissue after 4 weeks preservation in A3 and S3, while the negative control 18S rRNA copy number was 103 per milligram tissue. Preservation solutions can effectively inhibit the degradation of nucleic acid and maintain the tissue structure and cell integrity. This simple and effective preservation solution has a great significance for sample preservation, field specimen collection and subsequent molecular experiments.

Abstract:Concentrate liquid of Bacillus firmus PC465 was mixed thoroughly with the feed materials to produce granules at different doses of 106, 108 and 1010CFU/g dry matter; or freeze-dried and added to feed at a dose of 107CFU/g dry matter. Three feeding regimes were set up at feeding frequencies of “1+1”interval, “4+3”interval and continuous feeding. The effects of feeding B. firmus PC465 on growth and expression of STAT gene in Litopenaeus vannamei were studied at different adding doses and feeding frequencies. By adding PC465 at doses of 106, 108, and 1010CFU/g, significant improvements were observed in the growth rates and STAT gene expression levels in the lymphoid tissue of L. vannamei (P<0.05). The effect was the most significant in the continuous feeding treatment. The finding in this research may provide reference to the healthy aquaculture of shrimp.

Abstract:Porphyra haitanensis is an economically important marine crop in southern China. Due to global warming, farming of P. haitanensis was seriously affected by the increasing water temperature. In this study, the gametophytic blades of an F4 high temperature tolerance line (Z-61) and wild-type line (WT) were grown at normal temperature (21℃) and high temperature (30℃) under non-aerated condition for 0, 2, 4, 6, 8 and 10 days. Changes in four quality indices were measured, including contents of pigment, crude protein, total amino acids and free amino acids. The results showed that the quality of Z-61 was not significantly affected by the normal temperature and non-aeration. The quality of wild-type strain was even improved after a short-term cultivation under normal temperature and non-aeration, but the quality of Z-61 and wild-type strains were seriously affected by the high temperature and non-aeration stress. Furthermore, the results also indicated that the Z-61 could enhance its ability of high temperature tolerance by increasing the content of allophycocyanin (APC) and free amino acids. Our results would be helpful for understanding the mechanism of high temperature tolerance of P.haitanensis.

Abstract:A 113-day experiment was conducted to investigate the efficiency of bio-floc aquaculture technology (BFA) for water quality control, disease resistance and growth of Litopenaeus vannamei in intensive farming systems at different stocking densities. The experiment was carried out on traditional farming treatments (TF200, TF400, and TF600) and BFA farming treatments (BF200, BF400, and BF600) at stocking densities of 200, 400 and 600 ind/m2, respectively. The six groups of shrimp were kept in 18 indoor cement tanks. Bio-flocs were developed in BFA farming tanks by adding sucrose and probiotic with very little water exchange during the experiment. Traditional farming treatments were cultured with traditional methods. It was found that the water quality, special growth rate and survival rate of the shrimp deteriorated or reduced with the increase of stocking density in all treatments. However, BFA at stocking density of 400 ind/m2 revealed advantage in closed farming systems of L. vannamei, compared with the traditional farming at the same stocking density (TF400). In BF400, the bio-floc volume increased by 3.25-fold, while the concentrations of nitrite-N and ammonia-N decreased by 67.9% and 72.7%, respectively; Water consumption decreased about 33%, and body weight, survival, special growth rate and production per unit of L. vannamei increased by 14.5%, 156.3%, 2.4%, and 194.1%, respectively. The production of BFA farming at stocking density of 400 ind/m2 (BF400) was 4.01±0.94 kg/m2, showing the best environmental and production effect.

Abstract:For the application of a heterotrophic nitrifying-aerobic denitrifying bacteria strain X3 in mariculture, the effects of several environmental factors, including temperature, salinity, pH, C∶N ratio, and carbon source on the growth and nitrogen removing ability of strain X3 were examined in the laboratory conditions, and its sensitivity to different antibiotics was also explored. The results showed that, the optimal condition for strain X3 to grow and remove nitrogen were 28℃, salinity of 30, pH 8.5, using sodium acetate as the carbon source and at a C∶N ratio of 10∶1. This strain grew well and kept over 80% nitrogen removal rate at 25~37℃, 20~80 salinity, pH 7.5~9.5 with a C∶N ratio range of 5∶1~15∶1 and sodium acetate or glucose as the carbon source. Especially, this strain was able to grow in the medium with salinity of 150. The result of sensitivity to antibiotics indicated that strain X3 was only sensitive to norfloxacin, ofloxacin and polymyxa amphotericin B, while resistant to the other 27 antibiotics. Therefore, it can be concluded that strain X3 has excellent adaptability to the environment of mariculture and huge application potential in mariculture water purification.