Abstract:Protosalanx chinensis is a small economic fish distributed exclusively in the Eastern Asia and most of the relative research work was mainly conducted by Chinese researcher. We summarized the latest researches on ichthyology, growth, reproduction, incubation and embryo development, transplantation and yield fluctuation, invasiveness of P. chinensis in this paper. The corrected scientific name of this fish is not widely used yet. A large amount of genetic variations have been detected and morphological changes have also occured after transplanting for so many years. Growth rate differences in the same month explained why the ultimate body length of northern populations is not less than that of southern populations, although the growth period is shorter in northern area than southern area. Whether transition to feed on fish steadily or not determined the growth rate and ultimate body size of P. chinensis, however, diet base for size-structured populaton forming is not known yet. Whether size-structured populaton forms or not determins the sex selctive pattern, which has not been studied yet. P. chinensis performs spawning once in life span and the fertilizing rate of natural breeding is higher than artificial breeding, therefore, there is no need of stocking fertilized eggs if the appropriate number of reproductive individuals remain after commercial fishing. Embryo development and the impacting factors were well known which is enough for artificial production of fertilized eggs. P. chinensis is a kind of saline-alkaline tolerance species, and can serve as a candidate for saline-alkaline fisheries. It is agreed that overexploitation of diet resources accounts for the dramatic yield decline of P. chinensis, but the relative ecological research has not been conducted to guide the sustainable fisheries yet. We also suggested the countermeasures against invasion of P. chinensis.

Abstract:The moon jellyfish (Aurelia spp.) is a cosmopolitan species and often blooms to cause detrimental effects on human enterprises in many coastal waters. A population explosion of the sibling species Aurelia coerulea often occurred in the Yellow Sea and Bohai Sea in recent years. In addition, the moon jellyfish is one of the most common ornamental jellyfish in aquariums and holds great economic importance. Asexual reproduction is an important way for increasing the polyp population and expanding habitat. It is beneficial to understand the life history of the jellyfish deeply so as to grasp the asexual reproduction types and ways correctly. In this paper, we described the characteristics of asexual reproduction including stolon, budding, podocysts, longitudinal fission, and propagules reproduction by observation on more than 1000 A. coerulea polyps with a microscope. It was found that propagule bud can float under the surface of water and develop to the young polyp without sinking and adhering. A new form of rupture reproduction has been discovered, which only occurs in good condition with ample food supply. The comparison of the behavioral processes and function characteristics of six modes of asexual reproduction showed that stolon reproduction and rupture reproduction were beneficial to the rapid increase of the number of individuals in the polyp population; budding reproduction and longitudinal fission reproduction were conducive to the growth of offspring, podocysts reproduction helped the population to resist adverse environmental conditions. Propagules reproduction facilitated the migration of populations over long distances with water currents to expand or transfer habitats. Various asexual reproductions are the adaptive strategies of polyp population in response to different environmental conditions. The results are helpful to improve the breeding techniques and provide basic data for the further study of the population dynamics of Chinese coastal sea jellyfish and the exploration of the causes of large jellyfish outbreaks.

Abstract:Based on the data collected from bottom trawl surveys in Haizhou Bay in 2011 and 2013, the food composition and differences in trophic and spatial niche of Johnius belangerii, Larimichthys polyactis and Collichthys lucidus were studied by means of multivariate statistical analysis and niche overlap coefficient. The results showed that J. belangerii was a kind of benthic predator, mainly feeding on shrimp, amphipoda and polychaetes. L. polyactis belonged to the benthic and swimming predator, mainly feeding upon fish, shrimp, cephalopod and euphausiacea, C. lucidus belonged to the benthic and zooplankton predator, mainly feeding on shrimp, acetes, euphausiacea and mysidacea. Among the three Sciaenidae species, their trophic niche widths were relatively close, with the trophic niche width (2.69) and spatial niche width (2.78) of the L. polyactis being the highest. J. belangerii had the lowest values of trophic niche width (2.59) and C. lucidus had the highest spatial niche width value (2.42). The trophic niche overlap between the three Sciaenidae species was between 0.24 and 0.46, with J. belangerii and C. lucidus having the highest trophic niche overlap value (0.46). Their spatial niche overlap value was between 0.19 and 0.30, indicating that there was little spatial overlap among the three species, which alleviated the food competition. Their trophic-spatial niche overlap index was between 0.05 to 0.11, with J. belangerii and C. lucidus having the highest trophic–spatial niche overlap value (0.11). These species can reduce their interspecific competition by changing their food composition and space distribution.

Abstract:In order to understand the nutritional differences of grass carp cultured in traditional ponds and circulatory systems in ponds, a comparative study was conducted on nutritional components and nutritive quality between pond-and recirculating water system-reared grass carp; fish were fed with the same commercial diet. The results showed that pond group contained significantly higher moisture, crude fat, viscerosomatic index (VSI), pH reduction and drip loss, and lower crude protein and antioxidant function than the recirculating water system group. The constitutional ratio of essential amino acids met the Food and Agriculture Organization of the United Nations/Word Health Organization (FAO /WHO) standards and the content of Lys was the highest in essential amino acids in two culture models. However, the content of total amino acids (∑TAA), total delicious amino acids (∑DAA) and total sweet amino acids (∑SAA) in pond group were significantly lower than those of recirculating water system group. According to nutrition evaluation in amino acids score (AAS) and chemical score (CS), the first limiting amino acids were Val in two culture models. The contents of ∑n-3PUFA and ∑n-6PUFA in pond group were significantly higher than those of recirculating water system group, while contents of EPA + DHA in pond group were significantly lower than those of recirculating water system group. In conclusion, the nutritional composition of grass carp is reasonable; moreover, the recirculating water system culture is superior to pond culture in nutrition and flavor of grass carp.

Abstract:In this study, the suppressor of cytokine signaling 1 (SOCS1) genes socs1a and socs1b of Megalobrama amblycephala were used as genetic editing objects, and we screened out appropriate target synthetic guide RNA (gRNA) by online analysis. According to the mixture injection (gRNA and Cas9 protein) in the 1-2 cell stage embryos, the results of identifications of socs1 expression level by qRT-PCR and gene mutants by sequencing showed that we successfully established socs1 knock-out mutant. Compared with wild type, the growth performance and body mass of SOCS1a^+/- and SOCS1b^+/- were significantly increased, Meanwhile, the expression levels of inflammatory cytokines TNF-α and IL-6 were significantly increased, while the expression levels of IL-1β were not changed. After Aeromonas hydrophila injection, in contrast to the wild type, significant increases in levels of IL-6 and TNF-α mRNA were observed in both socs1a and socs1b heterozygous mutants. The duplicated socs1 knockout blunt snout bream has been successfully obtained by the CRISPR/Cas9 gene editing system, which provides a basis for further study of the socs1 gene. Meanwhile, our experimental results will provide a basis and reference for the CRISPR/Cas9 gene editing techniques in other aquaculture species.

Abstract:To explore the microbial community structure and changes in the intestine of Litopenaeus vannamei and its aquaculture environment during the cultivation process, Illumina MiSeq high-throughput sequencing platform was used to analyze the microbial community in the gut of L. vannamei at age of 46 and 86 days, and its aquaculture water and sediments correspondingly, based on the 16S rRNA sequence. The results showed that the Shannon-Wiener diversity indexes in water samples were significantly lower than those in sediments and shrimp intestines. We detected 35 phyla, 70 classes, 152 orders, 274 families and 420 genera that existed in water, sediments and L. vannamei intestines. There were more common microbes in the intestines of L. vannamei and the sediments than those in the water. The microbial community structure of water, sediments and L. vannamei intestines changed when culturing time prolonged, the different phyla of 46 and 86 d were Actinobacteria, Chlorobi, Fibrobacteres, Planctomycates and TM6. Relative abundance increased with time. However, the dominant flora was relatively fixed. At the phylum level, Proteobacteria, Bacteroidetes, Actinobacteria were the three dominant categories in all three kinds of samples. At the class level, Alphaproteobacteria, Betaproteobacteria and Actinobacteria were the dominant categories. In addition, L. vannamei intestines and sediment had the common dominant classes of Deltaproteobacteria, Gammaproteobacteria and Gemmatimonadetes. From the classification levels of order, family and genus, the microbial community relative abundance in various samples presented differences, so that few common categories showed overlapping dominance in samples except unclassified genera, which was the most abundant in all the samples. Besides, hgcI_clade was the dominant genus in the water, Ambiguous_taxa was the predominant genus in the L. vannamei intestines and sediments. These results further explained the correlation of the microbial community structure in intestine of L. vannamei and its aquaculture environment, and also showed the differences that emerged during the culture process.

Abstract:In order to explore the structural and functional differences between a TLR19 homolog (designated as ScTLR19) from S. curriculus and the reported TLR19 (designated as CiTLR19) from C. idellus, we cloned the full-length cDNA sequence of ScTLR19 gene and analyzed its sequence and structural characteristics, investigated its expression patterns of various tissues and the responses to grass carp reovirus (GCRV) infection with real-time fluorescent quantitative PCR (qPCR) technique, and revealed its distinct regulation on the downstream functional genes of TLR19 signaling pathway by overexpression experiments in this study. The results showed that the ScTLR19 gene encoded 957 amino acids, whose sequence shared high similarity (94.04%) with that of CiTLR19. The extracellular region of ScTLR19 protein consisted of nine leucine-rich repeats (LRRs), and harbored one more LRR than that for CiTLR19 at the amino acid sites of 654~677. The ScTLR19 also owned two more α-helixes and six more β-folds than that of CiTLR19 for the three dimensional structure. The transcriptional expressions of ScTLR19 were widely detected in various tissues of S. curriculus, and significantly up-regulated in kidney after GCRV infection. When the S. curriculus fin cells overexpressed ScTLR19 and were then challenged with GCRV, the transcriptional expressions of interferon regulatory factor 7 (IRF7) did not significantly change (P>0.05), while the transcriptional expressions of interferon regulatory factor 3 (IRF3) and both MyD88 and TRIF that were reported as two important adaptor proteins in TLR signal pathways, were significantly up-regulated at 12 h and 24 h post GCRV infection, compared to the control group (P<0.05). According to the previous study on CiTLR19, ScTLR19, just like CiTLR19, only regulated IRF3, but not IRF7 signal pathway during GCRV infection, but unlike CiTLR19 only regulating TRIF signal pathway, ScTLR19 could regulate both MyD88 and TRIF signal pathways, which might enable ScTLR19 with more antiviral immune functions to enhance the resistance against GCRV for S. curriculus. These results shed light on the differences in the structure and function between two TLR19 genes from S. curriculus and C. idellus.

Abstract:In order to investigate the polycyclic aromatic hydrocarbons pollution of pond aquaculture in Chongming Island, the contents and distribution of 16 PAHs in the sediments of 10 grass carp ponds in different areas of Chongming Island were analyzed by GC-MS. The sources of PAHs in ponds in different areas were analyzed by principal component analysis and characteristic ratio method. At the same time, the ecological risk was evaluated by sediment quality standard method and quality standard method. The results showed that the total PAHs content in the aquaculture sediment of grass carp pond in Chongming Island ranged from ND to 1 654.09 μg/kg, with an average content of 95.13 μg/kg, of which the contribution rate of PAHs in the 4-5 rings was high; the PAHs content in the sediment of grass carp pond in different areas of Chongming Island was quite different, the content of pond in the middle of island was low, and the content of pond around the island was high, especially in the west coastal area of of Chongming Island. PAHs mainly come from biomass combustion and oil combustion, which are generally at the lower middle pollution level, and the ecological risk is low, but there are potential ecological risks in the ponds along the west coast of the island, which should be paid attention to.

Abstract:Sexual dimorphism is widespread in animal kingdom and has been a hot topic in biology for a long time. In particular, the sex of the Mauremys mutica is determined by incubation temperature, however, the molecular mechanism of temperature response is still unclear. In order to understand the molecular mechanism of the sex differentiation of turtles, this study made a preliminary comparative analysis of the sex-differentiated lncRNAs and their target genes in the transcripts of M. mutica. First, the Illumina deep sequencing platform was used to perform comparative transcriptomics analysis of the testis and ovary of M. mutica by RNA-Seqs and screened to identify male and female differential transcripts. A total of 8 237 differentially expressed mRNAs and 9 573 differentially expressed lncRNAs were screened. Through GO functional annotation and KEGG pathway enrichment analysis, we found that these differential transcripts were mainly involved in the sex differentiation and gonadal development of turtles. In addition, a series of target genes related to reproductive development (gonad development and sex differentiation) regulated by DE lncRNA were obtained through the analysis of cis- and trans- effects. This study provides clues for further elucidating the temperature-dependent sex differentiation mechanism of M. mutica, and especially, it lays the foundation for further exploring the use of the sex determinants of turtles to conduct research on animal sexuality control breeding techniques for turtles.

Abstract:The highly conserved region of toxR gene of Vibrio rotiferianus was selected as the target fragment for the specific primer design. The recombinant plasmid was constructed based on the primers and we established a fluorescence quantitative PCR method for V. rotiferianus. And UF-150 Genechecker microfluidic quantitative real-time PCR instrument was used as a platform to develop a microfluidic quantitative real-time PCR detection method for V. rotiferianus via the optimized reaction system and reaction conditions. The results indicated that, this method can specifically amplify toxR gene target fragment, and the lower detection limit for V. rotiferianus is 1.34×10⁰ copies/μL. Artificial infection detection results show that the lower detection limit for V. rotiferianus in fish tissues is 1.34×10³ CFU/g. The results can be visually interpreted and the detection time was less than 42 min. This method has prominent advantages of strong specificity, high sensitivity and low site requirements, and it is suitable for developing practical field rapid detection technology of aquatic pathogens.

Abstract:The fat greenling (Hexagrammos otakii) is one of the most important commercial fishes found along northern coast of China, with fast growth rate, high nutritional value and wide consumer acceptance. In recent years, large-scale proliferation and release activities have been held to restore its natural resources. In order to analyze the genetic diversity and genetic differences between releasing population and natural population of H. otakii, mitochondrial DNA control region and four microsatellite markers were selected for assessment. Mitochondrial DNA control region results showed that the length of the first hypervariable region was 436 bp, and 117 haplotypes were observed in 413 H. otakii individuals, among which only Hap_3, Hap_7, Hap_17 were shared by different populations. Number of individuals in releasing population and wild population was 74 and 105, accounting for 46.54% and 41.34% respectively, and the nucleotide diversity in releasing population and wild population was 0.005 1-0.006 7, 0.005 8-0.007 5, while the haplotype diversity was 0.856 7-0.949 9 and 0.883 1-0.954 9, respectively. Both of them showed a high level of genetic diversity for releasing and wild populations. Microsatellite markers results showed that the average allele number (N_a) was 13-44, 13-27, and the average polymorphism information content (PIC) was 0.885 6, 0.874 0, respectively, which indicated that genetic polymorphism of releasing and wild population was moderately high; results of population genetic structure analysis showed that the genetic differentiation between released population and wild population was smaller, i.e. ata lower genetic differentiation level. In summary, rich genetic diversity existed in both populations, and there was no significant population differentiation in genetic structure, which indicates that the proliferation and release activities have no obvious genetic diversity impact on the wild population.

Abstract:In order to ensure the effect of fresh treatment on the characteristics of flavors of sturgeon meat during refrigerated storage, this experiment used solid phase microextraction-gas chromatography-mass spectrometry combined with electronic nose and electronic tongue technology to analyze chilled sturgeon meat with the fresh-keeping treatment of slightly acidic oxidation water and ε-polylysine during refrigerated storage. The result showed that the electronic nose can analyze the volatile components from the whole, and the data sets of the volatile odor of chilled sturgeon meat in the two groups had no overlapping areas, and the difference was obvious. SPME-GC-MS qualitatively identified 46 volatile substances, including aldehydes, ketones, hydrocarbons and alcohols. Among them, the main volatile substances of the fresh-keeping treatment group were caproaldehyde, enanthaldehyde, benzaldehyde, capryl aldehyde, nonanal, capric aldehyde, 2,5-octanedione, hypnone and 3,5-octanedipine-2-ketone. Thus, the preservation treatment can delay the production of astringency and the decline of flavor of chilled sturgeon meat. The bitterness, astringency and salty taste of chilled sturgeon meat during chilled storage were found to be lower than those of the control group. The two groups of samples showed significant differences in bitterness, astringency, salty taste and umami after 6 days of storage. The research showed the preservation treatment played a role in slowing down the decline of flavor of chilled sturgeon meat during refrigerated storage, and provided a theoretical basis for the application of chilled sturgeon meat preservation.

Abstract:This study evaluated the direct genetic effects (DGE) and indirect genetic effects (IGE) of Fenneropenaeus chinensis harvest body weight and eyeball abrasion at low rearing density. In order to accurately estimate the genetic parameters of harvest body weight and eyeball abrasion of F. chinensis, 6 408 shrimps from 178 tagged families of G8 and G9 generations (88 families in G8 and 90 families in G9) were tested. Each family was divided into three groups (12 shrimps per group), which were randomly placed in 3 different round cylinders (radius was 100 cm). A total of 88 cylinders were used in G8, 90 cylinders were used in G9. Each cylinder contained three different families. One family was combined with 6 other families. The harvest body weight and eyeball abrasion were recorded and evaluated after an 80-day growth test. The results showed that the heritability estimated for harvested body weight was low using the conventional animal model, which was 0.11±0.05. The results of likelihood ratio test showed that IGE should be included in the model (LRT=5.26). Total heritable variance of harvested body weight from the extended animal model containing IGE included DGE variance (43%), DGE-IGE genetic covariance (24%) and IGE variance (33%), which accounted for 24% of the phenotypic variance and more than twice the classical heritability (11%). The direct-indirect genetic correlation coefficient of harvested body weight estimated from DGE-IGE covariance was 0.32±0.45, which was a moderate positive correlation. The results indicated that the social interaction among individuals within the group was non-competitive because of the low breeding density. The heritability of eyeball abrasion using the logit model without IGE was low, which was 0.05 ±0.03. The ratio of total genetic variance including IGE to phenotypic variance was significantly greater than 1, which was 2.75 ($ {T}^{2} $). It was more than 58 times (0.05) of the heritability estimated from the logit model without IGE. Our results showed that social interactions produced more genetic variation of the harvest body weight of F. chinensis. Compared with harvested body weight, eyeball abrasion was more susceptible to social interactions, and could be an indicative trait reflecting the social interaction behavior among individuals.

Abstract:In order to study the influence of artificial reef on the sea bottom, based on the marine numerical model FVCOM (finite volume community ocean model) and its sediment transport module, the effects of the current field, suspended sediment and seabed sediment erosion and deposition around an artificial seamount in the artificial reef area of the Ma’an Islands are analyzed. A truncated-cone-type artificial seamount was set up with a diameter of 100 m and a height of 10 m. In order to simulate the effect of sediment suspension and seabed erosion and deposition around artificial seamount by the action of the tidal current, the part of the artificial seamount was simplified into a closed solid and the corresponding height of water depth was subtracted. Based on the analysis of the current field during the floods and ebbs of the spring and neap tides, the influence of artificial seamount on current velocity was mainly showed in the vicinity of the artificial seamount. The velocity of the water layer above the artificial seamount and velocity of bottom layer on both sides of the main current axis increased, while the velocity of downstream of the artificial seamount decreased significantly. The difference of suspended sediment concentration variation before and after the construction of artificial seamount was close to the trend of the current field variation and the maximum value was not more than 0.01 g/L. The results of sediment erosion and deposition on the sea bed around the artificial seamount showed deposition along the long axis of current ellipse, and erosion along the short axis of current ellipse, and the thickness of erosion and deposition were about ±0.5 m, and the horizontal influence range was within 2.0 times of the diameter around the reef mountain, that is, within 200 m. The sediment transport process caused by the artificial seamount was a local change process. In order to avoid local over erosion, it is necessary to reinforce the seabed near the artificial seamount on the short axis of the tide ellipse with special bottom pretection reef. It is not suitable to build artificial seamount in the area where tidal current velocity is too high and bottom sediment is liable to serious erosion and deposition.

Abstract:This study evaluated the gametic compatibility and zygotic fertility of Crassostrea ariakensis and C. gigas. The fertilization rate, deformity rate and hatching rate at different temperatures (18, 21, 24, 27, and 30 ℃), different salinities (16, 20, 24, 28, and 32) and different sperm concentrations (10⁰, 10¹, 10², 10³ and 10⁴ ind./μL) were compared. The results showed that symmetric fertilization was possible between C. gigas and C. ariakensis, and the zygote could successfully hatch. With the increase of salinity, the fertilization rate and hatcing rate of GG rose, while that of AA and AG rose first and then decreased. GA and AG had better gamete compatibility and zygotic fertility at salinity 28 and 24, in this case, the fertilization rate, deformity rate and hatching rate were 7.45%±5.05%, 2.00%±0.90%, 63.60%±9.88% and 14.26%±9.26%, 1.74%±0.93%, 66.16%±9.43%, respectively. With the increase of temperature, the fertilization rate and hatching rate of AA, GA and GG rose first and then decreased. The fertilization rate, deformity rate and incubation rate of GA and AG at temperature of 27 ℃ were severally 7.95%±4.04%, 1.79%±1.04%, 57.11%±9.95% and 14.70%±7.27%, 1.66%±0.85%, 67.25%±15.19%. With the increase of sperm concentration, the fertilization rate of GG gradually rose and the hatching rate mainly decreased, while the fertilization rate of GA and AG groups gradually increased. The fertilization rate, deformity rate and hatching rate of GA and AG at sperm concentration of 10⁴ ind./μL were severally 9.09%±7.53%, 1.59%±0.48%, 67.97%±19.96% and 14.30%±6.04%, 1.06%±0.68%, 67.33%±12.65%. This study indicate that temperature, salinity and sperm concentration had minor effect on gamete compatibility between C. gigas and C. ariakensis, but had conspicuous effect on zygotic fertility.